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Dr. Kennedy's Vocabulary Course: -E-
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(A B C D E F G H I J K L M)
 
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Ron Kennedy, M.D.
 
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(A B C D E F G H I J K L M)
-emia:  Suffix meaning blood or referring to the presence of a substance in the blood. As for example, anemia (lack of blood) and hypervolemia (too high a volume of blood).
-ectomy:  A surgical suffix referring to the removal of something. For example, a lumpectomy is the surgical excision of a lump which may be benign or not, tonsillectomy is the removal of the tonsils, a partial colectomy is removal of part of the colon, an appendectomy is removal of the appendix, etc. From the Greek "ek" (out) + "tome" (a cutting) = a cutting out.
ECST:  stands for the exercise cardiac stress test, the most widely used cardiac (heart) screening test. In an ECST the patient exercises on a treadmill according to a standardized protocol, with progressive increases in the speed and elevation of the treadmill (typically changing at three-minute intervals). During the ECST, the patient's electrocardiogram (EKG), heart rate, heart rhythm, and blood pressure are continuously monitored. If a coronary arterial blockage results in decreased blood flow to a part of the heart during exercise, certain changes may be observed in the EKG (the electrocardiogram), as well as in the response of the heart rate and blood pressure. The accuracy of the ECST in predicting significant coronary artery disease (CAD) depends in part on the "pre-test likelihood" of CAD (also known as Bayes' theorem). In a patient at high risk for CAD (for example, because of advanced age or multiple coronary risk factors), an abnormal ECST is quite accurate (over 90% accurate) in predicting the presence of CAD. However, a relatively normal ECST may not mean there is an absence of significant coronary artery disease in a patient with the same high risk factors (so-called "false negative ECST"). In a patient at low risk for CAD, a normal ECST is quite accurate (over 90%) in predicting the absence of significant CAD. And an abnormal ECST test may not reflect the true presence of CAD (so-called "false-positive ECST"). The ECST may miss the presence of significant CAD and so give a false negative result. Or the ECST may indicate the presence of significant CAD when, in fact, there is none and so yield a false-positive test result. These false-negative and false-positive results are due to a variety of cardiac circumstances, which may include: An abnormal EKG at rest, which may be due to abnormal serum electrolytes, abnormal cardiac electrical conduction, or certain medications, such as digitalis; Heart conditions not related to CAD, such as mitral valve prolapse (drooping) or hypertrophy (increased size) of the heart; or an inadequate increase in the heart rate and/or blood pressure during exercise. If the initial ECST does not clarify the diagnosis, additional tests are often used to clarify the condition. These further options include radionucleide isotope injection and ultrasound of the heart (stress echocardiography) during the stress test.
Ecstasy:  1. A state of rapture and trancelike elation. 2. A street name for 3-4 methylenedioxymethamphetamine (MDMA), also called "Adam," "ecstasy," or "XTC" on the street, a synthetic, psychoactive (mind altering) drug with hallucinogenic and amphetamine-like properties. Its chemical structure is similar to two other synthetic drugs, MDA and methamphetamine. Problems that users encounter with MDMA are similar to those found with the use of amphetamines and cocaine, including: psychological difficulties, including confusion, depression, sleep problems, drug craving, severe anxiety, and paranoia during and sometimes weeks after taking MDMA (in some cases, psychotic episodes have been reported) and physical symptoms such as muscle tension, involuntary teeth clenching, nausea, blurred vision, rapid eye movement, faintness, and chills or sweating. Increases in heart rate and blood pressure, a special risk for people with circulatory or heart disease. MDMA use was reported to cause permanent damage to the brain and lead to symptoms resembling those in Parkinson's disease. However, this report was later retracted because the monkeys and baboons in the study were not injected with MDMA but, by mistake, with another drug.
ECT (Electroconvulsive Therapy):  A procedure in which an electric current is passed through the brain to produce controlled convulsions (seizures) to treat patients with depression, particularly for those who cannot take or are not responding to antidepressants, have severe depression, or are at high risk for suicide. Electroconvulsive therapy (ECT) is believed to act by a massive neurochemical release in the brain due to the controlled seizure. The most common side effect is short-term memory loss, which usually resolves quickly. ECT typically relieves depression within 1 to 2 weeks after beginning treatments.
Ectodermal Dysplasia:  A genetic disorder in which there is abnormal development of the skin and associated structures (the hair, nails, teeth, and sweat glands). The most dangerous problem occurs in cases with decreased sweating due to absence of the sweat glands. Affected persons have trouble controlling fevers and being in a warm environment. The hair may also be absent or sparse. The skin tends to be thin and light in color. Problems with the lining inside the nose predispose to chronic nasal infections. The teeth may be notably absent or develop abnormally. There are a number of different types of ectodermal dysplasia. X-linked anhidrotic (non-sweating) ectodermal dysplasia is most common. As an X-linked trait, it mainly affects males. There is also an autosomal dominant form affecting males and females alike. The term "ectodermal dysplasia" refers to the abnormal development (dysplasia) of structures derived from the ectoderm, one of the germ cell layers in the embryo.
Ectoparasite:  A parasite that lives on or in the skin but not within the body. Fleas and lice are ectoparasites. Infestation with an ectoparasite is called an ectoparasitosis.
Ectopia Cordis:  A type of birth defect in which the heart is abnormally located. In ectopia cordis, the heart usually protrudes outside the chest.
Entamoeba histolytica:  The agent of amebic dysentery, a disorder with inflammation of the intestine and ulceration of the colon. Entamoeba histolytica is a single-celled parasite that is transmitted to humans via contaminated water and food. It can also infect the liver and other organs.
Akathisia:  A syndrome characterized by unpleasant sensations of "inner" restlessness that manifests itself with an inability to sit still or remain motionless, [a without] + káthisis sitting]. Its most common cause is as a side effect of medications, mainly neuroleptic antipsychotics especially the phenothiazines which are used to treat schizophrenia.
E. coli:  Short for Escherichia coli, the colon bacillus, a bacterium that normally resides in the human colon. E. coli has been studied intensively in genetics and molecular and cell biology because of its availability, its small genome size, its normal lack of pathogenicity (disease-causing ability), and its ease of growth in the laboratory. Most strains of E coli are quite harmless. However, some strains of E. coli are capable of causing disease, sometimes disease of deadly proportions. For example, an outbreak of E. coli O157:H7 bacteria in the water supply hit Walkerton, Ontario in the year 2000; the E. coli affected about 2,000 people in and around Walkerton and were responsible for the deaths of some 18 people. E. coli 0157:H7 is a major health problem. About 20,000 cases of hemorrhagic (bloody) colitis (inflammation of the bowel) due to E. coli 0157:H7 occur each year in the U.S. E coli O157:H7 produces toxins (poisons). The toxins produced by E. coli 0157:H7 can damage the lining of the intestine and are thought to participate in all of the diseases caused by E. coli 0157:H7. The hemorrhagic diarrhea (bloody colitis) caused by E. coli 0157:H7 is severe with painful abdominal cramps, gross blood in the stool, and lasts for 6 to 8 days. Children with E. coli 0157:H7 can develop a disease called the hemolytic-uremic syndrome (HUS), a major and sometimes fatal "Hemolytic" refers to the breakup of red blood cells. This leads to anemia and a shortage of platelets (thrombocytopenia) which causes abnormal bleeding. "Uremic" refers to the acute kidney failure. Central nervous system problems with seizures and coma can also occur. HUS is the most common cause of acute kidney failure in infants and young children. Persons who get E. coli 0157:H7, particularly the elderly, can develop a syndrome similar to HUS called thrombotic thrombocytopenic purpura (TTP) with anemia due to fragmentation of red blood cells, shortage of platelets (thrombocytopenia) with easy bruising, neurologic abnormalities, impaired kidney function, and fever. Most commonly, E. coli 01257:H7 comes from eating raw or undercooked ground beef (hamburger) or from drinking raw milk or contaminated water. Less commonly, E coli O157:H7 can be transmitted from one person to another.
E. coli hemorrhagic diarrhea:  Bloody colitis (inflammation of the bowel) caused by E. coli, usually by the strain E. coli 0157:H7. The diarrhea is severe with painful abdominal cramps, gross blood in the stool, and lasts for 6 to 8 days. Most commonly, E. coli 01257:H7 comes from eating raw or undercooked ground beef (hamburger) or from drinking raw milk or contaminated water. Less commonly, E coli O157:H7 can be transmitted from one person to another.
Eagle syndrome:  Inflammation of the styloid process, a spike-like projection sticking off the base of the skull. The tissues in the throat rub on this structure during the act of swallowing causing pain. The diagnosis of Eagle syndrome is made by history and an x-ray showing the abnormal styloid process. Anti-inflammatory drugs are the first line of treatment although surgical removal of the styloid process may be needed.
Ear bones:  The malleus, incus, and stapes the bones of the middle ear which conduct vibrations from the ear drum to teh inner ear.
Ear infection, middle (acute):  Acute middle ear infection, medically called acute otitis media is inflammation of the middle ear. Acute otitis media typically causes fluid in the middle ear accompanied by signs or symptoms of ear infection: a bulging eardrum usually accompanied by pain; or a perforated eardrum, often with drainage of purulent material (pus).
Ear piercing:  A method of body mutilation using a needle or needle gun to make holes through the ear lobe or other parts of the ear for wearing jewelry. When done under hygienic conditions, there is little danger from ear piercing other than localized and transitory inflammation. Unhygienic conditions, handling the new piercing with unwashed hands, or the use of irritating jewelry can result in inflammation and/or infection. Infected ear piercings should be washed and then treated with antibiotic cream. One may choose to either allow the piercing to close or to use only non-irritating jewelry (usually gold or hypoallergenic plastic). The likelihood of inflammation and infection is greater for piercings that go through hard cartilage, as found on the side and top of the outer ear, than with the soft bottom lobe of the ear.
Ear pit:  Tiny pit in front of the ear: preauricular pit. A minor anomaly of no great consequence in itself. More common in blacks than whites and in females than males. Can recur in families. The presence of 2 or more minor anomalies in a child increases the probability that the child has a major malformation.
Ear puncture:  Puncture of the ear drum may be due to an accident for example when something is stuck into the ear. Or it may be due to fluid pressure in the middle ear. Today the ear drum is occasionally punctured on purpose with surgery. A surgically placed tiny incision (a myringotomy) is made in the eardrum. Any fluid, usually thickened secretions, is removed and an ear tube may be inserted.
Ear ringing:  Together with other abnormal ear noises, ear ringing is medically called tinnitus. Tinnitus can arise in any of the four sections of the ear: the outer ear, the middle ear, the inner ear, and the brain. It can be due to many causes including ear infection, fluid in the ears, Meniere syndrome, medications such as aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs), aging, and ear trauma (such as from the noise of planes, firearms, or loud music). In rare situations, tinnitus may reflect an aneurysm or an acoustic neuroma (a benign tumor on the acoustic nerve). Woodwind players are more likely to experience tinnitus than other orchestral players, probably because they usually sit just in front of the brass. If tinnitus persists and its cause is unknown, a hearing test (audiogram) should be done. Measures can be taken to lessen the intensity of tinnitus or to mask it.
Ear tag:  Common minor anomaly, a rudimentary tag of ear tissue, often containing a core cartilage, usually located just in front of the ear (auricle). Therefore also called preauricular tag. The presence of 2 or more minor anomalies in a child increases the probability that the child has a major malformation.
Ear thermometer:  A thermometer that registers body temperature via the ear canal. The ear thermometer was invented in 1964 by Dr. Theodor H. Benzinger. Dr. Benzinger worked from 1947 to 1970 at the Naval Medical Research Institute in Bethesda, Maryland where he studied temperature regulation and helped create the field of biothermodynamics. He created the ear thermometer while looking for a way to take a person's temperature and get a reading as close as possible to the temperature center of the brain temperature, the hypothalamus. Because the hypothalamus and the eardrum share blood vessels, Benzinger decided to use the ear canal to take a reading. (Until that time, attaching electrodes to the hypothalamus was the only way to get a brain temperature reading.) The ear temperature most closely correlates with the brain temperature and is said, therefore, if properly taken, the best body temperature reading. No one is sure why the temperature of the brain is a better indication of metabolism than say the temperature of the rectum or the tongue. Also, electronic thermometers are not as accurate as mercury themometers.
Ear tubes:  Formally known as tympanostomy tubes, ear tubes are small plastic tubes inserted into the eardrum (the tympanum or tympanic membrane) to keep the middle ear aerated for a prolonged period of time. To put the tubes in place, a myringotomy (a surgically placed tiny incision in the eardrum) is done. Any fluid, usually thickened secretions, will be removed. The ear tubes usually remain in place for 6 months to several years. Water should not be allowed to enter the ear canal while the tubes are in place. Eventually, they will move out of the eardrum (extrude) and fall into the ear canal. The doctor may remove the tube during a routine future office visit or it may simply fall out of the ear without the child realizing it.
Ear wax:  A natural wax-like substance secreted by special glands in the skin on the outer part of the ear canal. It repels water, and traps dust and sand particles. Usually a small amount of wax accumulates, and then dries up and falls out of the ear canal carrying with it unwanted particles. Ear wax is helpful in normal amounts and serves to coat the skin of the ear canal where it acts as a temporary water repellent. The absence of ear wax may result in dry, itchy ears, and even infection. There are two types of ear wax: wet and dry. Most whites and blacks have the wet type while most Asians and Native Americans have the dry type. The gene for wet ear wax on chromosome 16 appears to predispose to breast cancer.
Ear, cauliflower:  An acquired deformity of the external ear to which wrestlers and boxers are particularly vulnerable. The cause is damage due to trauma. When trauma causes a blood clot under the skin of the ear, the clot disrupts the connection of the skin to the ear cartilage. The cartilage has no other blood supply except the overlying skin so, if the skin is separated from the cartilage, the cartilage is deprived of nutrients and dies and the ear cartilage shrivels up to form the classic cauliflower ear. The treatment of the hematoma (the blood clot) is to drain it through an incision in the ear and apply a compressive dressing to sandwich the two sides of the skin against the cartilage. When treated promptly and aggressively, the development of cauliflower ear deformity is unlikely. Delay in diagnosis and treatment leads to more difficulty in managing this problem and may leave greater ear deformity.
Ear, external (outer):  There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The external ear looks complicated but it is functionally the simplest part of the ear. It consists of the pinna or auricle (the visible projecting portion of the ear), the external acoustic meatus (the outside opening to the ear canal), and the external ear canal that leads to the ear drum. In sum, there is the pinna, the meatus and the canal. And the external ear has only to concentrate air vibrations on the ear drum and make the drum vibrate. The external ear is also called the outer ear.
Ear, inner (internal):  There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The inner ear is far and away the most highly complex. The essential component of the inner ear for hearing is the membranous labyrinth where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end. The membranous labyrinth is a system of communicating sacs and ducts (tubes) filled with fluid (the endolymph). The membranous labyrinth is lodged within a cavity called the bony labyrinth. At some points the membranous labyrinth is attached to the bony labyrinth and at other points the membranous labyrinth is suspended in a fluid (the perilymph) within the bony labyrinth. The bony labyrinth has three parts: a central cavity (the vestibule), semicircular canals (which open into the vestibule) and the cochlea (a snail-shaped spiral tube). The membranous labyrinth also has a vestibule which consists of two sacs (called the utriculus and sacculus) connected by a narrow tube. The larger of the two sacs, the utriculus, is the principal organ of the vestibular system or system of balance. This system informs us about the position and movement of the head. The smaller of the two sacs, the sacculus, is also connected by membranous tube to the cochlea that contains the organ of Corti. The hair cells, which are the special sensory receptors for hearing, are found within the organ of Corti.
Ear, low-set:  A minor anomaly involving an ear situated down below its normal location. Technically, the ear is low-set when the helix (of the ear) meets the cranium at a level below that of a horizontal plane through both inner canthi (the inside corners of the eyes). The presence of 2 or more minor anomalies in a child increases the probability that the child has a major malformation.
Ear, middle:  There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The middle ear consists of the ear drum (the tympanum or tympanic membrane) and, beyond it, a cavity. This cavity is connected via a canal (the Eustachian tube) to the pharynx (the nasopharynx). The Eustachian tube permits the gas pressure in the middle ear cavity to adjust to external air pressure so, as you're descending in a plane, it's the Eustachian tube that opens when your ears "open." The middle ear cavity also contains a chain of 3 little bones (ossicles) that connect the ear drum to the internal ear. The ossicles are named the malleus, incus, and stapes. In terms of function, the middle ear communicates with the pharynx, equilibrates with external pressure and transmits the ear drum vibrations to the inner ear.
Ear, slanted:  An ear that is slanted more than usual. Technically, an ear is slanted when the angle of the slope of the auricle is more than 15 degrees from the perpendicular. Also called a malrotated ear Considered a minor anomaly. The presence of 2 or more minor anomalies in a child increases the probability that the child has a major malformation.
Earache:  Pain in the ear. This can occur because of conditions within the ear itself, the ear canal, or the visible external portion of the ear. Acute infection of the middle ear, medically called acute otitis media, is inflammation of the middle ear and is the most frequent diagnosis in sick children in the US. The eustachian tube is shorter in children than adults which allows easy entry of bacteria and viruses into the middle ear, resulting in acute otitis media in childhood. Infection of the ear canal (otitis externa) is also called swimmer's ear. Otitis externa is typically caused by bacterial infection. Earache can also be due to pain and inflammation of the outer portion of the ear. A child with a draining ear should not fly (or swim).
Eardrum:  The tympanic membrane of the ear, or tympanum, the membrane that separates the middle ear from the external ear.
Eastern equine encephalitis:  Abbreviated EEE. A mosquito-born viral disease. The EEE virus normally is found in freshwater swamp birds and mosquitoes that do not bite people. However, the virus is occasionally transmitted to other types of mosquitoes capable of biting horses and people. The risk of contracting EEE is highest in mid-to-late summer. The mosquitoes are killed by frost. The first symptoms are fever (103-106ºF), stiff neck, and headache starting 2-10 days after infection. Swelling of the brain (encephalitis) is the most feared feature. The disease gets worse quickly, and many patients go into a coma within a week and some die. Those who survive suffer mild to severe neurologic deficits. Very few people recover completely. There is an EEE vaccine for horses, but not yet for people. The best way to avoid EEE is to avoid mosquito bites (easier said than done).
Eat Right 4 Your Type Diet:  The Eat Right 4 Your Type Diet is a weight loss plan based upon the concept that your blood type (referring to the ABO blood types: O, A, B, and AB) influences the foods that will be healthiest for you and which foods will be “empty” calories that add up to excess weight. Sometimes referred to as the “blood type diet,” the plan makes specific dietary recommendations based upon your blood type and urges followers to eat only foods that are harmonious with their own blood type. The diet was popularized by Peter D’Adamo, a naturopathic physician in the 1996 book Eat Right 4 Your Type. Critics of the diet emphasize that there has been no evidence published in the medical literature to demonstrate the effectiveness of the theory or method.
EBCT (electron beam computerized tomography):  A new (and controversial) noninvasive test for the detection of coronary artery disease (CAD). EBCT, or Ultrafast CT (as the technique will be termed here) is designed to measure calcium deposits in the coronary arteries. In patients with CAD, the plaques which make up the blockages contain significant amounts of calcium, which can be detected with Ultrafast CT. This test will identify calcium in blockages as mild as 10-20%, which would not be detected by standard physiologic stress testing. The importance of detecting such mild blockages is controversial, however, because the only "treatment" that is used for such blockages typically involves risk factor modification (especially cholesterol reduction and smoking cessation as well as aspirin and certain vitamins). A potential limitation of Ultrafast CT is that only a total calcium score is reported. This means that two or three separate blockages of about 30% each will result in the same score as a single 70-80% blockage. The Ultrafast CT does not give an image of specific separate areas of calcification. The major value of Ultrafast CT appears to be in screening young patients with one or more risk factors for the development of CAD. Ultrafast CT scanning is of limited value for older patients in whom some degree of calcification is commonly found. Additionally, for the reasons described above, the detection of some calcification may not be reflective of significant CAD. Ultrafast CT was reported to be a better test than treadmill-ECG or technetium-stress test for detecting CAD (J Am Coll Cardiol 2000;36:32-38,326-340). The authors favored it as "a reasonable alternative to traditional stress testing" (pointing also to its cost, brief test time and the fact that a physician does not usually need to be present during the scan). In the same journal, the American College of Cardiology and the American Heart Association issued a consensus statement opposing the widespread use of Ultrafast CT. The controversy continues.
Ebola virus:  A notoriously deadly virus that causes fearsome symptoms, the most prominent being high fever and massive internal bleeding. Ebola virus kills as many as 90% of the people it infects. It is one of the viruses that is capable of causing hemorrhagic (bloody) fever. Epidemics of Ebola virus have occurred mainly in African countries including Zaire (now the Democratic Republic of Congo), Gabon, Uganda, the Ivory Coast, and Sudan. Ebola virus is a hazard to laboratory workers and, for that matter, anyone who is exposed to it. Infection with Ebola virus in humans is incidental -- humans do not "carry" the virus. The way in which the virus first appears in a human at the start of an outbreak has not been determined. However, it has been hypothesized that the first patient (the index case) becomes infected through contact with an infected animal. Ebola virus is transmitted by contact with blood, feces or body fluids from an infected person or by direct contact with the virus, as in a laboratory. People can be exposed to Ebola virus from direct contact with the blood or secretions of an infected person. This is why the virus has often been spread through the families and friends of infected persons: in the course of feeding, holding, or otherwise caring for them, family members and friends would come into close contact with such secretions. People can also be exposed to Ebola virus through contact with objects, such as needles, that have been contaminated with infected secretions. The incubation period -- the period between contact with the virus and the appearance of symptoms -- ranges from 2 to 21 days.
EBV:  Epstein-Barr virus, best known as the cause of infectious mononucleosis ("mono"). Infection with EBV is characterized by fatigue and general malaise. Infection with EBV is fairly common and is usually a transient and minor thing. However, in some individuals EBV can trigger chronic illness, including immune and lymphoproliferative syndromes. It is a particular danger to people with compromised immune systems, such as from AIDS. EBV was at one time believed to be the cause of the chronic fatigue syndrome, but chronic infection with this virus actually produces a separate (if similar) disorder. EBV is a double-stranded DNA virus in the herpes family of viruses.
Ecchymosis:  The skin discoloration caused by the escape of blood into the tissues from ruptured blood vessels. Ecchymoses can similarly occur in mucous membranes as, for example, in the mouth.
ECG:  Abbreviation for electrocardiogram or EKG. The K is from "kardio" (in German).
Echinacea:  An herb that has been claimed to boost the body's immune system and help fight off infections. Echinacea has been widely used to treat the symptoms of upper respiratory tract infections (URIs), including colds and the flu. The herb is derived from the purple coneflower, Echinacea purpurea, a drought-tolerant perennial plant native to North America with large purple flowers surrounding a large cone. However, the efficacy of echinacea in treating URIs has not been established. In a randomized placebo-controlled trial, echinacea was found not to shorten the duration of a cold or lessen its severity in children (JAMA 2003;290:2824-2830).
Echinococcosis:  Parasitic disease caused by the larval stage of the tapeworm Echinococcus. There are three forms of Echinococcus that affect humans -- E. (Echinococcus) granulosus, E. multilocularis, and E. vogeli -- and each has a different geographic distribution and tends to cause a different pattern of disease. E. granulosus is common in areas where livestock is raised in association with dogs -- in Australia and New Zealand, Argentina and Chile, Africa, E. Europe, the Middle East, and the Mediterranean region, especially Lebanon and Greece -- and causes unilocular cysts. E. multilocularis is found in Alpine, sub-Arctic, or Arctic regions -- including Canada, the United States, and central and northern Europe and Asia -- and causes multilocular lung disease known as alveolar hydatid disease (AHD). E. vogeli is found only in Central and South America and causes polycystic hydatid disease.
Echocardiography:  Echocardiography is a diagnostic test which uses ultrasound waves to make images of the heart chambers, valves and surrounding structures. It can measure cardiac output and is a sensitive test for inflammation around the heart (pericarditis). It can also be used to detect abnormal anatomy or infections of the heart valves.
Echocardiography, stress:  A supplement to the routine exercise cardiac stress test. During stress echocardiography, the sound waves of ultrasound are used to produce images of the heart at rest and at the peak of exercise. In a heart with normal blood supply, all segments of the left ventricle (the major pumping chamber of the heart) exhibit enhanced contractions of the heart muscle during peak exercise. Conversely, in the setting of coronary artery disease (CAD), if a segment of the left ventricle does not receive optimal blood flow during exercise, that segment will demonstrate reduced contractions of heart muscle relative to the rest of the heart on the exercise echocardiogram. Stress echocardiography is very useful in enhancing the interpretation of the routine exercise cardiac stress test (ECST). It can be used to exclude significant CAD in patients who are suspected of having a "false-positive" ECST, a falsely abnormally result on the screening ECST test.
Echocardiography, transesophageal:  A diagnostic test which is done through the esophagus and which employs ultrasound waves to make images of the heart chambers, valves and surrounding structures. Transesophageal echocardiography (TEE) may be used, for example, in the treatment of children having heart surgery. TEE has unusually accurate imaging capabilities that permit the identification of previously unidentified anatomic features and postoperative surgical results that may necessitate a change in surgical plan or surgical revision before the child leaves the operating suite.
Echolalia:  The involuntary parrotlike repetition (echoing) of a word or phrase just spoken by another person. Echolalia is a feature of schizophrenia (especially the catatonic form), Tourette syndrome, and some other disorders. From echo + the Greek lalia, a form of speech.
Echopraxia:  The involuntary imitation of the movements of another person. Echopraxia is a feature of schizophrenia (especially the catatonic form), Tourette syndrome, and some other neurologic diseases. From echo + the Greek praxia meaning action.
Echovirus:  A group of viruses found in the gastrointestinal tract. The "echo" part of the name stands for enteric cytopathic human orphan viruses. "Orphan" implied that they were viruses not associated with any disease. However, it is now known that echoviruses can cause a number of different diseases including rashes, diarrhea, respiratory infections (the common cold, sore throat, bronchitis, and bronchiolitis), myositis (muscle inflammation), meningitis, encephalitis, and pericarditis (inflammation of the membrane around the heart).
Eclampsia:  Convulsions (seizures) occurring with pregnancy-associated high blood pressure and having no other cause.
Eclosion:  The emergence of an adult insect from its pupal case, or the hatching of an insect larva from an egg. From the French éclosion, from éclore, to open.
Ecogenetics:  The interaction of genetics with the environment. The genetic disease PKU (phenylketonuria) provides an illustration of ecogenetics. Persons with PKU lack an enzyme to process an amino acid (phenylalanine) and so require a special environment: a diet low in phenylalanine.
Economy class syndrome:  The formation of blood clots in veins deep within the legs -- deep vein thrombosis -- occurring during (or just after) a long airplane flight, especially in economy class (tourist class) where there is the least space allotted per passenger and ones legs tend especially to be immobilized for lack of leg room. The economy class syndrome is directly related to immobility for long periods during which blood pools in the legs, raising the risk of clot formation. The tendency to immobility is often compounded by the fasten-seat belt sign, the presence of carts in the aisles, etc. Other risk factors contributing to the syndrome include lower oxygen pressure and dehydration. Changes in oxygen pressure in the cabin tend to decrease the oxygen level in the blood. The air in the cabin lacks the normal degree of humidity which contributes to dehydration. The serving of coffee, tea, and alcoholic beverages (all of which are diuretics) further causes passengers to become dehydrated. The economy class syndrome is not confined to that class on a plane. It is recommended that all persons traveling on air flights, irrespective of which class they are in, drink lots of water and move their legs by walking whenever possible and by periodically flexing and extending their ankles, knees, and hips to minimize the risk of economy class syndrome. Deep vein thrombosis is potentially serious and can even have fatal consequences.
Ectopic:  In the wrong place. Out of place. An ectopic kidney, for example, is one that is not in the usual location. The term "ectopic" comes from the Greek "ektopis" meaning "displacement" ("ek", out of + "topos", place = out of place).
Ectopic pregnancy:  A pregnancy that is not in the uterus. The fertilized egg settles and grows in any location other than the inner lining of the uterus. The large majority (95%) of ectopic pregnancies occur in the Fallopian tube. However, they can occur in other locations, such as the ovary, cervix, and abdominal cavity. An ectopic pregnancy occurs in about 1 in 60 pregnancies. Most ectopic pregnancies occur in women 35 to 44 years of age.
Ectrodactyly:  The congenital absence of all or part of one or more fingers or toes. The term ectrodactyly has been applied to a variety of malformations of the fingers or toes. Cases of ectrodactyly are usually sporadic (with no family history of this malformation). As a rule, one hand is involved and the feet are not affected. Congenital constriction rings ("amniotic bands") are sometimes associated with the malformation. The word ectrodactyly is derived from the Greek ektroma (abortion) and daktylos (finger) = literally, abortion (of a) finger.
Eczema:  A particular type of inflammatory reaction of the skin in which there are typically vesicles (tiny blister-like raised areas) in the first stage followed by erythema (reddening), edema (swelling), papules (bumps), and crusting of the skin followed, finally, by lichenification (thickening) and scaling of the skin. Eczema characteristically causes itching and burning of the skin. Eczema, which is also called atopic dermatitis, is a very common skin problem. It may start in infancy, later in childhood, or in adulthood. Once it gets underway, it tends not to go quickly away.
EDC (Estimated date of confinement):  The estimated calendar date when the baby will be born.
Edema:  The swelling of soft tissues as a result of excess water accumulation. Edema is often more prominent in the lower legs and feet toward the end of the day as a result of pooling of fluid from the upright position maintained during the day. Upon awakening from sleeping, patients can have swelling around the eyes referred to as "periorbital edema."
Edema, hereditary angioneurotic:  A genetic form of angioedema. (Angioedema is also referred to as Quinke's disease.) Persons with it are born lacking an inhibitor protein (called C1 esterase inhibitor) that normally prevents activation of a cascade of proteins leading to the swelling of angioedema. Patients can develop recurrent attacks of swollen tissues, pain in the abdomen, and swelling of the voice box (larynx) which can compromise breathing. The diagnosis is suspected with a history of recurrent angioedema. It is confirmed by finding abnormally low levels of C1 esterase inhibitor in the blood. Treatment options include antihistamines and male steroids (androgens) that can also prevent the recurrent attacks. Also called hereditary angioedema.
Edema, lymphatic (Lymphedema):  A common chronic, debilitating condition in which excess fluid called lymph collects in tissues and causes swelling in them. Lymphedema may occur in the arms or legs. This often happens after lymph vessels or lymph nodes in the axilla (arm pit) or groin are removed by surgery or damaged by radiation, impairing the normal drainage of lymphatic fluid. Lymphedema may also due to a mass such as a tumor pressing on the lymphatic vessels. Congenital lymphedema: In many other cases, lymphedema is evident at birth and is due to a congenital malformation (that is, a birth defect) of the lymphatic system.
Edentulism:  Without teeth. Complete loss of all natural teeth can substantially reduce quality of life, self-image, and daily functioning.
Edwards syndrome (Trisomy 18):  Children with this syndrome have an extra chromosome 18 with a characteristic pattern of multiple malformations and mental retardation. Features include low birth weight, small head (microcephaly), small jaw (micrognathia), malformations of the heart and kidneys, clenched fists with abnormal finger positioning, and malformed feet. The mental retardation is profound with an IQ too low to measure. Nineteen out of 20 of these children die before their first birthday. The condition is named after the British physician and geneticist John Edwards who discovered the extra chromosome in 1960.
EECP (Enhanced external counterpulsation):  A non-invasive out-patient treatment for heart disease and, in particular, for angina (chest pain due to an inadequate supply of oxygen to the heart muscle). EECP is designed to relieve angina by improving perfusion in areas of the heart deprived of an adequate blood supply. EECP uses a device to inflate and deflate a series of compressive cuffs that are wrapped around the calves and lower and upper thighs. The basic principle involved is that of counterpulsation. The cuffs inflate during diastole, the period when the heart muscle relaxes and the chambers fill with blood. The cuffs inflate sequentially from the calves upwards, resulting in increased pressure in the aorta and coronary arteries, thus stretching those vessels. Compression of the vascular bed in the legs also increases the return of venous blood to the heart and increases cardiac output. Patients are customarily treated with EECP for an hour a day for a total of 35 hours. This achieves what is achieved with IV chelation therapy with EDTA in about the same number of treatments, but at an increased cost.
EEE (Eastern equine encephalitis):  A mosquito-born viral disease. The EEE virus normally is found in freshwater swamp birds and mosquitoes that do not bite people. However, the virus is occasionally transmitted to other types of mosquitoes capable of biting horses and people. The risk of contracting EEE is highest in mid-to-late summer. The mosquitoes are killed by frost. The first symptoms are fever (103-106ºF), stiff neck, and headache starting 2-10 days after infection. Swelling of the brain (encephalitis) is the most feared feature. The disease gets worse quickly, and many patients go into a coma within a week and some die. Those who survive suffer mild to severe neurologic deficits. Very few people recover completely. There is an EEE vaccine for horses, but not yet for people. The best way to avoid EEE is to avoid mosquito bites (easier said than done).
EEG (Electroencephalogram):  a technique for studying the electrical current within the brain. Electrodes are attached to the scalp. Wires attach these electrodes to a machine which records the electrical impulses. The results are either printed out or displayed on a computer screen. Different patterns of electrical impulses can denote various problems in the brain including different forms of epilepsy. Most EEGs see only a moment in time within the brain, and can catch only gross abnormalities in function. An overnight EEG is designed to check the electrical activity in the brain of a sleep-deprived patient, increasing the chance that seizure activity will be revealed. Also available are 24- or 48-hour EEGs, which measure electrical activity over one or two days, usually using mobile EEG units.
Effacement:  The thinning of the cervix which occurs before and while it dilates.
Effective dose:  The dose of a drug that will achieve the desired effect.
Efferent:  Carrying away. An artery is an efferent vessel carrying blood away from the heart. An efferent nerve carries impulses away from the central nervous system. The opposite of efferent is afferent.
Efferent nerve:  A nerve that carries impulses away from the central nervous system (CNS). An efferent nerve is the opposite of an afferent nerve that carries impulses toward the CNS.
Efferent vessel:  A vessel carrying blood away from the heart. An artery or arteriole.
Effusion:  Too much fluid, an outpouring of fluid. A hemorrhagic effusion is one that has blood within the fluid. A pericardial effusion is an outpouring of fluid within the fibrous sac (the pericardium) that surrounds the heart. The lungs are covered by two-layered membranes which are called the pleura. A pleural effusion involves the presence of an excessive amount of pleural fluid (between the two layers of the pleural membranes). The term "effusion" comes from the Latin "effusio" meaning a pouring out.
EGD (Esophagogastroduodenoscopy):  a test to visualize the lining of the esophagus, stomach, and duodenum using a tubular fiberoptic device.
EGF (Epidermal growth factor):  A polypeptide (small protein) that is a powerful mitogen (stimulates cells to enter mitosis, cell division). EGF promotes cell growth and differentiation, is essential in embryogenesis, and is important in wound healing. It is produced by many normal cell types and is made in large amounts by some tumors. The EGF gene is on chromosome 4q25 (whereas the gene for its receptor, EGFR, is on chromosome 7). The kidney is the main source of circulating EGF. EGF is also known as urogastrone (URG).
EGFR (Epidermal growth factor):  A receptor A protein found on the surface of cells to which epidermal growth factor (EGF) binds. When EGF attaches to EGFR, it activates the enzyme tyrosine kinase, triggering reactions that cause the cells to grow and multiply. EGFR is found at abnormally high levels on the surface of many types of cancer cells, which may divide excessively in the presence of EGF. The drug Iressa attaches to EGFR and thereby inhibits the attachment of EGF and stops cell division. The gene for EGFR is on chromosome 7p12.3-p12.1. The EGFR molecule has 3 regions -- one projects outside the cell and contains the site for binding EGF; the second is embedded in the cell membrane; and the third projects into the cytoplasm of the cell's interior.
Egg:  Ovum, the female germ cell.
Egg sac:  The "egg sac" or ovary is one of a pair of reproductive glands in women. They are located in the pelvis, one on each side of the uterus. Each ovary is about the size and shape of an almond. The ovaries have two functions: production of eggs (ova) and female hormones. Each month, during the menstrual cycle, an egg is released from one ovary. The egg travels from the ovary through a fallopian tube to the uterus. The ovaries are the main source of female hormones (estrogen and progesterone). These hormones control the development of female body characteristics, such as the breasts, body shape, and body hair. They also regulate the menstrual cycle and pregnancy.
Ehlers-Danlos syndrome (EDS):  A heritable disorder of connective tissue with easy bruising, joint hypermobility (loose joints), skin laxity, and weakness of tissues. There are a number of different types of Ehlers-Danlos syndrome which share the foregoing features but can be categorized into at least nine different types.
Ehrlich, Paul:  (1854-1915) Renowned German scientist and physician. Born near Breslau, Ehrlich got his start there working in the laboratory of his cousin, Carl Weigert, a pathologist who pioneered the use of aniline dyes as biological stains. Ehrlich became interested in the selectivity of these dyes. He showed that they react specifically with cells and subcellular structures and that all of these dyes can be classified as basic, acid or neutral. His classic work on the staining of granules in white blood cells helped lay the foundations of hematology and histology. Following a bout with tuberculosis, Ehrlich developed a method for staining the bacillus that caused his disease. His method became the basis of the method still used today to stain and identify the bacillus of tuberculosis. From Ehrlich's work also came the basis for the Gram stain for bacteria, a key technique in bacteriology.
Ehrlichiosis:  An acute (abrupt onset) disease, first reported in humans in 1986, due to infection by the rickettsial agent, Ehrlichia canis. The brown dog tick, is the common vector (carrier). Ehrlichiosis is clinically similar to Rocky Mountain spotted fever with high fever, headache, malaise, and muscle pain but without a rash. Laboratory features include leukopenia (low white blood cell count), thrombocytopenia (low platelet count), mild anemia, and elevation in the levels of hepatic aminotransferase enzymes. Clinical symptoms and laboratory abnormalities respond promptly to therapy with the antibiotics tetracycline or doxycycline, and the majority of patients become afebrile within 24 to 48 hours after the start of such treatment. The diagnosis of ehrlichiosis rests on the detection of ehrlichia either by direct means or by the indirect means of serologic studies. Three methods are available for detection: inspection of peripheral-blood smears, PCR testing, and tissue culture. The disease ehrlichiosis is named for the great German Nobel Prize winning physician and bacteriologist Paul Ehrlich (1854-1915).
Eicosanoid:  A lipid mediator of inflammation derived from the 20-carbon atom arachidonic acid (20 in Greek is "eicosa") or a similar fatty acid. The eicosanoids include the prostaglandins, prostacyclin, thromboxane, and leukotrienes.
Eicosapentaenoic acid (EPA):  One of the principal omega-3 fatty acids. The body has a limited ability to manufacture EPA by converting the essential fatty acid, alpha-linolenic acid (ALA) which is found in flaxseed oil, canola oil or walnuts.
Eidetic:  1. Marked by extraordinarily accurate and vivid recall, especially of images. 2. By extension, an individual with such exceptional powers. Eidetic memory is the ability to see in one's mind's eye in the most minute detail. From the German eidetisch, from the Greek eidetikos and eidos (form),
Eight-day measles:  An acute highly contagious viral disease with fever, runny nose, cough, red eyes, and a spreading skin rash. The eight-day measles is the ordinary measles, also known as rubeola, a potentially disastrous disease. Measles may be complicated by ear infections, pneumonia, encephalitis (that can cause convulsions, mental retardation. and even death), the sudden onset of low blood platelet levels with severe bleeding (acute thrombocytopenic purpura) or a chronic brain disease that occurs months to often years after an attack of measles (subacute sclerosing panencephalitis). During pregnancy measles may trigger miscarriages or premature delivery. The disease is also called the hard measles and (depending on how long you think it lasts) the seven day measles, the nine-day measles, or the ten-day measles, and morbilli. The name measles comes from the Middle English maselen meaning many little spots referring, of course, to the rash.
Eighth cranial nerve:  The eighth cranial nerve is the vestibulocochlear nerve. The vestibulocochlear nerve is responsible for the sense of hearing and it is also pertinent to balance, to the body position sense. Problems with the vestibulocochlear nerve may result in deafness, tinnitus (ringing or noise in the ears), dizziness, vertigo and vomiting. The 12 cranial nerves, the vestibulocochlear nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
Eisoptrophobia:  An abnormal and persistent fear of mirrors. Sufferers experience undue anxiety even though they realize their fear is irrational. Because their fear often is grounded in superstitions, they may worry that breaking a mirror will bring bad luck or that looking into a mirror will put them in contact with a supernatural world inside the glass.
Ejaculate:  To ejaculate is to release semen during an orgasm in a male.
Ejaculation:  Ejection of sperm and seminal fluid.
Ejaculatory duct:  A canal in the male formed by union of the vas deferens and the duct from the seminal vesicle. The ejaculatory duct passes through the prostate. Semen passes through them at the time of ejaculation.
Ejection fraction:  The portion of blood that is pumped out of a filled ventricle as a result of a heartbeat. The heart does not eject all of the blood that is in the ventricle. Only about two-thirds of the blood is normally pumped out with each beat. That fraction is referred to the ejection fraction. The ejection fraction is an indicator of the heart's health. If the heart is diseased from a heart attack or another cardiac condition, the ejection fraction may fall, for example, to a third. Only a third of the blood in the ventricle (half the normal two-thirds) is pumped out. The heart in this case has 1/2 its usual power.
Elastic fiber:  A slender fiber in connective tissue that is rich in the protein elastin and has an elastic quality.
Elastin:  A protein that coil and recoils like a spring within the elastic fibers of connective tissue and accounts for the elasticity of structures such the skin, blood vessels, heart, lungs, intestines, tendons, and ligaments. Elastin functions in connective tissue together with collagen. Whereas elastin provides elasticity, collagen provides rigidity to connective tissue. Elastin is normally no longer made after puberty and aging begins. Also called elasticin.
Elastin degrading enzyme (Elastase):  An enzyme that digests and degrades a number of proteins including elastin, an elastic substance in the lungs and some other organs that supports their structural framework. Elastase is specifically inhibited by alpha-1 antitrypsin.
Elbow (elbow joint):  The juncture of the long bones in the middle portion of the arm. The bone of the upper arm (humerus) meets both the ulna (the inner bone of the forearm) and radius (the outer bone of the forearm) to form a hinge joint at the elbow. The radius and ulna also meet one another in the elbow to permit a small amount of rotation of the forearm. The elbow therefore functions to move the arm like a hinge (forward and backward) and in rotation (outward and inward). The biceps muscle is the major muscle that flexes the elbow hinge, and the triceps muscle is the major muscle that extends it. The primary stability of the elbow is provided by the ulnar collateral ligament, located on the medial (inner) side of the elbow. The outer bony prominence of the elbow is the lateral epicondyle, a part of the humerus bone. Tendons attached to this area can be injured, causing inflammation or tendonitis (lateral epicondylitis, or tennis elbow). The inner portion of the elbow is a bony prominence called the medial epicondyle of the humerus. Additional tendons from muscles attach here and can be injured, likewise causing inflammation or tendonitis (medial epicondylitis, or golfer's elbow).
Elbow arthritis:  Can be due to many systemic forms of arthritis, including rheumatoid arthritis, gouty arthritis, psoriatic arthritis, ankylosing spondylitis, and Reiter's disease. Generally, they are associated with signs of inflammation of the elbow joint, including heat, warmth, swelling, pain, tenderness, and decreased range of motion. Range of motion of the elbow is decreased with arthritis of the elbow because the swollen joint impedes the range of motion.
Elbow bursitis:  At the tip of the elbow (the olecranon), there is a bursa (a fluid-filled sac that functions as a gliding surface to reduce friction with motion). This bursa is known as the olecranon bursa. Because of its location, the olecranon bursa is subject to trauma, ranging from simple repetitive weight bearing while leaning, to banging in a fall. This trauma can cause a common, aseptic form of bursitis (olecranon bursitis) with varying degrees of swelling, warmth, tenderness and redness in the area overlying the point of the elbow.
Elbow cellulitis:  Inflammation of the skin around the elbow due to infection (cellulitis) commonly occurs as a result of abrasions or puncture wounds permitting bacteria on the surface of the skin to invade the deeper layers of the skin. This causes inflamed skin characterized by heat, redness, warmth, and swelling. The most common bacteria that cause cellulitis include Staphylococcus ("Staph") and Streptococcus ("Strep"). One can have an associated low-grade fever. Cellulitis generally requires antibiotic treatment, either orally or intravenously. Heat application can help in the healing process.
Elbow dislocation (elbow subluxation, nursemaid's elbow):  Partial dislocation of the elbow. The radius (a bone in the forearm) slips out of the ligament that holds it in place at the elbow. This is common in children under 4 years of age. It may be due to an adult lifting or swinging the child by one hand and can also occur when an infant rolls over or falls. The child begins to cry immediately and holds the arm slightly bent at the elbow with the forearm against the abdomen. Treatment is for the physician to reduce the dislocation. Once a child has had nursemaid's elbow, it may recur. The term nursemaid's elbow harks back to the days when a nursemaid (nanny) was not a rarity. The condition today should probably be called babysitter's elbow. It is also known as dislocation of the radial head, elbow dislocation, pulled elbow, radial head subluxation, slipped elbow, or toddler elbow.
ELBW (extremely low birth weight):  An ELBW baby is one born very prematurely weighing between 401 and 1000 grams (about 14 to 35 ounces) at birth. Extremely low birth weight babies are at the lower limits of viability. If ELBW babies survive, they are at elevated risk for neurological abnormalities, hearing and visual impairment, and developmental delay in infancy. The lower a baby's weight at birth, the more likely the child is to be subject to such problems.
Elder abuse:  The physical, sexual, or emotional abuse of an elderly person, usually one who is disabled or frail. Elder abuse is an umbrella term used to describe one or more of the following: Physical abuse is the willful infliction of physical pain or injury,such as slapping, bruising, sexually molesting, or restraining. Sexual abuse is the infliction of non-consensual sexual contact of any kind. Emotional or psychological abuse is the infliction of mental or emotional anguish, such as humiliating, intimidating, or threatening. Financial or material exploitation is the improper act or process of an individual, using the resources of an older person, without his/her consent, for someone else's benefit. Neglect is the failure of a caretaker to provide goods or services necessary to avoid physical harm, mental anguish or mental illness, such as abandonment, denial of food or health related services. Self-neglect is characterized as the behavior of an elderly person that threatens his/her own health or safety. Like child abuse, elder abuse is a crime that all health and social services professionals are mandated to report.
Elective:  In medicine, something chosen ("elected"). An elective procedure is one that is chosen (elected) by the patient or physician that is advantageous to the patient but is not urgent. Elective surgery is decided by the patient or his or her doctor. The procedure is seen as beneficial but not absolutely essential at that time.
Elective mutism:  Complete lack of speech (mutism) that is believed to be volitional (willed) on the part of the patient. True elective mutism may be a reaction to a traumatic event, the aftermath of an injury to the mouth or throat, particularly if it is painful, or a symptom of extreme shyness. In some cases, the lack of speech is eventually found not to be volitional, but a sign of damage or deformity of the speech apparatus, or a feature of infantile autism.
Elective surgery:  Surgery that is subject to choice (election). The choice may be made by the patient or doctor. For example, the time when a surgical procedure is performed may be elective. The procedure is beneficial to the patient but does not need be done at a particular time, as opposed to emergency surgery.
Electro-oculography (EOG):  A type of electrophysiologic retinal testing done to measure the difference in the electrical potential between the front and back of the eye in response to dark and light.
Electrocardiogram:  A recording of the electrical activity of the heart. An electrocardiogram is a simple, non-invasive procedure. Electrodes are placed on the skin of the chest and connected in a specific order to a machine that, when turned on, measures electrical activity all overaround the heart. Output is usually in the form of a long scroll of paper displaying a printed graph of activity. Newer models output the data directly to a computer and screen, although a print-out may still be made.
Electrocoagulation:  The coagulation (clotting) of tissue using a high-frequency electrical current applied locally with a metal instrument or needle with the aim of stopping bleeding. There is also, for example, laser coagulation and photocoagulation.
Electrocochleography (ECochG or ECoG):  A test that measures the electrical potentials generated in the inner ear in response to stimulation by sound. Electrocochleography may be done, for example, to confirm the diagnosis of Ménière disease.
Electroconvulsive therapy (ECT):  A procedure in which an electric current is passed through the brain to produce controlled convulsions (seizures) to treat patients with depression, particularly for those who cannot take or are not responding to antidepressants, have severe depression, or are at high risk for suicide. ECT is believed to act by a massive neurochemical release in the brain due to the controlled seizure. The most common side effect is short-term memory loss, which usually resolves quickly. ECT typically relieves depression within 1 to 2 weeks after beginning treatments.
Electrodesiccation:  Use of an electric current to destroy cancerous tissue and control bleeding.
Electroencephalogram (EEG):  A study of electrical current within the brain. Electrodes are attached to the scalp. Wires attach these electrodes to a machine which records the electrical impulses. The results are either printed out or displayed on a computer screen. Different patterns of electrical impulses can denote various problems within the brain including different forms of epilepsy. Most EEGs see only a moment in time within the brain, and can catch only gross abnormalities in function. An overnight EEG is designed to check the electrical activity in the brain of a sleep-deprived patient, increasing the chance that seizure activity will be revealed. Also available are 24- or 48-hour EEGs, which measure electrical activity over one or two days, usually using mobile EEG units.
Electrogastrogram:  A study in which the electrical current generated by the muscle of the stomach is sensed and recorded. Thus, it is analogous to an electrocardiogram of the heart. The electrogastrogram, like the electrocardiogram, is performed by taping electrodes to the skin; however, in the case of the electrogastrogram the electrodes are placed on the upper abdomen over the stomach. The recordings from the muscle are stored and analyzed by a computer. The electrogastrogram is performed to diagnose motility disorders of the stomach, that is, when the muscles of the stomach are not working normally.
Electrolarynx:  A battery-operated instrument that makes a humming sound to help people who have lost their larynx to talk.
Electrolysis:  Permanent removal of body hair, including the hair root, with an electronic device. While it is billed as a permanent process, many people find that hair does grow back (albeit slowly) after electrolysis.
Electrolyte:  An electrolyte is a substance that will dissociate into ions in solution and acquire the capacity to conduct electricity. The electrolytes include sodium, potassium, chloride, calcium and phosphate. Informally, called lytes. (lyte comes from the Greek lytos meaning may be dissolved.)
Electromyogram (EMG):  A test used to record the electrical activity of muscles. When muscles are active, they produce an electrical current that is usually proportional to the level of muscle activity. An EMG is also called a myogram. The EMG can detect abnormal muscle electrical activity in many diseases and conditions, including muscular dystrophy, inflammation of muscles, pinched nerves, peripheral nerve damage (damage to nerves in the arms and legs), amyotrophic lateral sclerosis (ALS) (also known as Lou Gehrig disease), myasthenia gravis, disc herniation, and others. The EMG helps to distinguish between muscle conditions in which the problem begins in the muscle and muscle weakness due to nerve disorders.
Electron beam computerized tomography (EBCT):  A relatively new (and controversial) noninvasive test for the detection of coronary artery disease (CAD). EBCT, or Ultrafast CT (as the technique will be termed here) is designed to measure calcium deposits in the coronary arteries. In patients with CAD, the plaques which make up the blockages contain significant amounts of calcium, which can be detected with Ultrafast CT. This test will identify calcium in blockages as mild as 10-20%, which would not be detected by standard physiologic stress testing. The importance of detecting such mild blockages is controversial, however, because the only "treatment" that is used for such blockages typically involves risk factor modification (especially cholesterol reduction and smoking cessation as well as aspirin and certain vitamins). A potential limitation of Ultrafast CT is that only a total calcium score is reported. This means that two or three separate blockages of about 30% each will result in the same score as a single 70-80% blockage. The Ultrafast CT does not give an image of specific separate areas of calcification. The major value of Ultrafast CT appears to be in screening young patients with one or more risk factors for the development of CAD. Ultrafast CT scanning is of limited value for older patients in whom some degree of calcification is commonly found. Additionally, for the reasons described above, the detection of some calcification may not be reflective of significant CAD. Ultrafast CT was reported to be a better test than treadmill-ECG or technetium-stress test for detecting CAD (J Am Coll Cardiol 2000;36:32-38,326-340). The authors favored it as "a reasonable alternative to traditional stress testing" (pointing also to its cost, brief test time and the fact that a physician does not usually need to be present during the scan). In the same journal, the American College of Cardiology and the American Heart Association issued a consensus statement opposing the widespread use of Ultrafast CT. The controversy continues.
Electron microscope (EM):  A microscope in which an electron beam replaces light to form the image. EM has its pluses (greater magnification and resolution than optical microscopes) and minuses (you are not really "seeing" objects, but rather you are looking at their electron densities, and meaningless artifacts may abound). Nonetheless, EM has extended the range of the microscope. EM was invented by a team led by Vladimir Zworykin, an engineer at the RCA Laboratory in Camden, New Jersey. The device was publicly unveiled in 1940.
Electronystagmogram (ENG):  A recording of the eye movements, usually done to confirm the presence of nystagmus. Electronystagmogram may be done in cases of vertigo to determine if there is damage to the vestibular portion of the acoustic nerve. The test may be done in cases of possible acoustic neuroma, Meniere disease, positional vertigo, and labyrinthitis.
Electrophoresis:  A process by which molecules (such as hormones, proteins, DNA, or RNA fragments) can be separated according to size and electrical charge by applying an electric current to them. Each kind of molecule travels through the medium at a different rate, depending on its electrical charge and molecular size.
Electrophrenic respiration (diaphragm pacing):  A procedure to help patients with spinal cord injuries to breathe. Their breathing is helped by setting the respiratory rate by electrical stimulation of the phrenic nerve. The pacing is accomplished via electrodes surgically implanted into the diaphragm, which is innervated by the phrenic nerve. This procedure is currently experimental. It is being tested in patients with injuries that cut across the cervical spinal cord high in the neck and result in paralysis of all four limbs (tetraplegia) and respiratory failure requiring chronic mechanical ventilatory support. For the procedure to work, the function of the phrenic nerve must be normal. Diaphragm pacing originally required surgery opening the chest cavity (thoracotomy) to implant the electrodes. It is now done by laparoscopy through small openings in the chest.
Electrophysiologic retinal testing:  Testing done to diagnose specific disorders of the retina, including inherited retinal diseases, the effects of toxic drug exposure on the retina, and the presence of foreign bodies within the eye. The most commonly performed electrophysiologic test is the electroretinogram (ERG). Other electrophysiologic tests include electro-oculography (EOG), visual evoked response (VER), dark adaptometry, and special color vision testing. The ERG measures the electrical response of the retina to flashes of light. The EOG measures the difference in the electrical potential between the front and back of the eye in response to dark and light. The VER measures the electrical potential resulting from a visual stimulus. Dark adaptometry measures the period of time which passes before the retina regains its maximal sensitivity to low amounts of light when going from conditions of bright light to darkness.
Electrophysiology:  The biomedical field dealing with the study of electric activity in the body. Electrophysiology includes the study of the production of electrical activity and the effects of that electrical activity on the body. See examples above.
Electroshock (electroconvulsive therapy) (EST, ECT):  A procedure in which an electric current is passed through the brain to produce controlled convulsions (seizures) to treat patients with depression, particularly for those who cannot take or are not responding to antidepressants, have severe depression, or are at high risk for suicide. The procedure is believed to act by a massive neurochemical release in the brain due to the controlled seizure. The most common side effect is short-term memory loss, which usually resolves quickly. EST typically relieves depression within 1 to 2 weeks after beginning treatments.
Electrosurgery:  Instead of using a scalpel, the surgeon utilizes a heat-generating electrical device to burn or vaporize tissue in order to remove it and minimize and halt bleeding.
Elephantiasis (lymphatic filariasis):  A mosquito-borne parasitic disease caused by tiny thread-like worms that live in the human lymph system. Best known from dramatic photos of people with grossly enlarged or swollen arms and legs. The parasitic worms responsible for the disease include Wuchereria bancrofti, Brugia malayi, and Brugia timori. The disease currently affects 120 million people worldwide, and 40 million of these people have serious disease. When an infected female mosquito bites a person, she may inject the worm larvae, called microfilariae, into the blood. The microfilariae reproduce and spread throughout the bloodstream, where they can live for many years. Often disease symptoms do not appear until years after infection. As the parasites accumulate in the blood vessels, they can restrict the circulation and cause fluid to build up in surrounding tissues. The most common, visible signs of infection are excessively enlarged arms, legs, genitalia, and breasts. Medicines to treat lymphatic filariasis are most effective when used soon after infection. The disease is difficult to detect early. Improved treatment and laboratory tests are needed.
Elevated hemidiaphragm:  Elevation of half of the diaphragm, the muscle that separates the chest cavity from the abdomen and that serves as the main muscle of respiration. The elevation of a hemidiaphragm is a significant sign of a problem. That problem may lie below, within or above the diaphragm: Below the diaphragm -- In the abdomen there may be a cyst, an infection or abscess, hematoma (collection of blood), a tumor, or abdominal surgery. In the diaphragm -- The hemidiaphragm may be paralyzed or lax because of damage to the phrenic nerve (that controls the diaphragm) or infiltration of the diaphragm by lung cancer or another tumor. bove the chest -- In the chest there may be atelectasis (lung collapse), lung fibrosis, painful pleurisy, pulmonary embolus, or a rib fracture. An elevated hemidiaphragm may be suspected on the physical examination and confirmed on an X-ray or CT of the chest or upper abdomen. It is also called a raised hemidiaphragm.
Eleventh cranial nerve:  The eleventh cranial nerve is the accessory nerve. The twelve cranial nerves, the accessory nerve included, emerge from or enter the skull (the cranium) as opposed to the spinal nerves which emerge from the vertebral column. The accessory is so-called because, although it arises in the brain, it receives an additional (accessory) root from the upper part of the spinal cord. The accessory nerve supplies the sternocleidomastoid and trapezius muscles. The sternocleidomastoid muscle is in the front of the neck and turns the head. The trapezius muscle moves the scapula (the wingbone), turns the face to the opposite side, and helps pull the head back. Damage to the accessory nerve can be isolated (confined to the accessory nerve) or it may also involve the ninth and tenth cranial nerves which exit through the same opening (foramen) from the skull . Accessory neuropathy (nerve disease) can sometimes occur and recur for unknown reasons. Most patients recover. Paralysis of the accessory nerve prevents rotation of the head away from that side and causes drooping of the shoulder.
ELISA stands for "enzyme-linked immunosorbent assay.":  This is a rapid immunochemical test that involves an enzyme (a protein that catalyzes a biochemical reaction). It also involves an antibody or antigen (immunologic molecules). ELISA tests are utilized to detect substances that have antigenic properties, primarily proteins (as opposed to small molecules and ions such as glucose and potassium). Some of these include hormones, bacterial antigens and antibodies.
Elliptocytosis:  Hematologic disorder characterized by elliptically shaped red blood cells (elliptocytes) with variable breakup of red cells (hemolysis) and varying degrees of anemia. It is inherited as a dominant trait and is due to mutation (change) in one of the genes encoding proteins of the red cell membrane keleton.
Embolism, paradoxical:  Passage of a blood clot (thrombus) from a vein to an artery. When clots in veins break off (embolize) , they travel first to the right side of the heart and, normally, then to the lungs where they lodge. The lungs act as a filter to prevent the clots from entering the arterial circulation. However, when there is a hole in the wall between the two upper chambers of the heart (an atrial septal defect), a clot can cross from the right to the left side of the heart, then pass into the arteries as a paradoxical embolism. Once in the arterial circulation, a clot can travel to the brain, block a vessel there, and cause a stroke (cerebrovascular accident or CVA). Because of the risk of stroke from paradoxical embolism, it is usually recommended that even small atrial septal defects be repaired.
Embolism, pulmonary:  The obstruction of the pulmonary artery or a branch of it leading to the lungs by a blood clot, usually from the leg, or foreign material causing sudden closure of the vessel. (Embolus is from the Greek "embolos" meaning plug.) The risk factors for pulmonary embolism include advanced age, cancer, genetic predisposition, immobilization (especially in the hospital), pelvic or leg trauma, pregnancy, and surgery. The diagnosis of pulmonary embolism can be difficult because the symptoms are nonspecific and may mimic many other diseases. Pulmonary angiography is the gold standard test. Other tests may include oximetry and arterial blood gas analysis and imaging such as chest x-rays and ultrasonography. The treatment includes anticoagulants such as heparin and warfarin (Coumadin). About 10- 15% of patients with pulmonary embolism die from it.
Embolus:  Something that travels through the bloodstream, lodges in a blood vessel and blocks it. Examples of emboli are a detached blood clot, a clump of bacteria, and foreign material such as air. Pulmonary emboli are blood clots that have been carried through the blood into the pulmonary artery (the main blood vessel from the heart to the lung) or one of its branches, plugging that vessel. Emboli is the plural of embolus, a word that comes from the Greek "embolos" meaning a wedge or plug.
Embryo:  The organism in the early stages of growth and differentiation from fertilization to, in humans, the beginning of the third month of pregnancy. After that point in time, it is termed a fetus.
Embryonal carcinoma:  A malignant germ cell tumor that occurs most often in the testes and accounts for about 40% of testicular tumors. Under the microscope, these tumors may resemble tissues of early embryos. This type of tumor can grow rapidly and spread outside the testicle. It usually occurs before the age of 30 and is often prepubertal. (Embryonal carcinoma of the ovary is rare.)
Embryonic hemoglobin (Hemoglobin E):  The normal embryonic hemoglobin, the main type of hemoglobin found in the human embryo. The E stands for embryonic.
Emergency contraception:  The prevention of pregnancy after unprotected vaginal intercourse. Emergency contraception may use drugs related to the female hormones estrogen and progesterone. These "morning-after pills" are similar to birth control pills but generally contain higher hormone doses. Another form of emergency contraception uses an intrauterine device (IUD) inserted by a physician within 5 days after intercourse.
Emergency medical technician (EMT):  A person trained in the performance of the procedures required in emergency medical care. You are most likely to find an EMT working with a mobile emergency response team, such as an ambulance or fire and rescue team. Some EMTs are employed in emergency rooms, or are hired to be present at sporting events, camps, or other locations where emergency response might be needed.
Emergency physician:  A physician focused on the immediate decision making and action necessary to prevent death or any further disability both in the prehospital setting by directing emergency medical technicians and in the emergency department. The emergency physician provides immediate recognition, evaluation, care, stabilization, and disposition of a generally diversified population of adult and pediatric patients in response to acute illness and injury.
Emerging infectious disease:  An infectious disease that has newly appeared in a population or that has been known for some time but is rapidly increasing in incidence or geographic range. Examples of emerging infectious diseases include: Ebola virus (first outbreaks in 1976 and the discovery of the virus in 1977), HIV/AIDS (virus first isolated in 1983), hepatitis C (first identified in 1989, now known to be the most common  cause of post-transfusion hepatitis worldwide), Influenza A(H5N1) virus (well known pathogen in birds but first isolated from humans in 1997), Legionella pneumophila (first outbreak in 1976 as Legionnaire disease and since associated with similar outbreaks linked to poorly maintained air conditioning systems), E. coli O157:H7 (first detected in 1982, often transmitted through contaminated food, has caused outbreaks of hemolytic uremic syndrome), and Borrelia burgdorferi (first detected in 1982 and identified as the cause of Lyme disease). Another example of an emerging infectious disease is the new variant of Creutzfeldt-Jakob disease, which was first described in 1996. The agent is considered to be the same as that causing bovine spongiform encephalitis, a disease which emerged in the 1980s and affected thousands of cattle in the UK and Europe.
Emesis Vomiting:  An emesis basin is usually kept handy for surgery patients recovering from general anesthesia since nausea and vomiting are common in that situation.
Emesis Vomiting:  An emesis basin is usually kept handy for surgery patients recovering from general anesthesia since nausea and vomiting are common in that situation.
Emetic:  Something that causes emesis, that makes you want to vomit. For example, ipecac is an emetic.
Emetic:  Something that causes emesis, that makes you want to vomit. For example, ipecac is an emetic.
Emetophobia:  An abnormal and persistent fear of vomiting. Sufferers of emetophobia experience undue anxiety even though they realize their fear is irrational. They usually are especially worried about vomiting in public and embarrassing themselves. Consequently, they often avoid office meetings, banquets, dances and other social gatherings. The anxiety produced by this phobia can cause stomach "butterflies" and nausea.
Emetophobia:  An abnormal and persistent fear of vomiting. Sufferers of emetophobia experience undue anxiety even though they realize their fear is irrational. They usually are especially worried about vomiting in public and embarrassing themselves. Consequently, they often avoid office meetings, banquets, dances and other social gatherings. The anxiety produced by this phobia can cause stomach "butterflies" and nausea.
EMG (Electromyogram):  A test used to record the electrical activity of muscles. When muscles are active, they produce an electrical current that is usually proportional to the level of muscle activity. An electromyogram (EMG) is also called a myogram. The EMG can detect abnormal muscle electrical activity in many diseases and conditions, including muscular dystrophy, inflammation of muscles, pinched nerves, peripheral nerve damage (damage to nerves in the arms and legs), amyotrophic lateral sclerosis (ALS) (also known as Lou Gehrig disease), myasthenia gravis, disc herniation, and others. The EMG helps to distinguish between muscle conditions in which the problem begins in the muscle and muscle weakness due to nerve disorders. There are two types of EMG - the intramuscular EMG and the surface EMG. Intramuscular EMG (the most commonly used type) involves inserting a needle electrode through the skin into the muscle whose electrical activity is to be measured. Surface EMG (SEMG) involves placing the electrodes on (not into) the skin overlying the muscle to detect the electrical activity of the muscle. In both types of EMG, the electrical activity is displayed visually on an oscilloscope and may also be displayed audibly through a microphone.
EMG syndrome:  (The exomphalos-macroglossia-gigantism syndrome or Beckwith-Wiedemann syndrome) An overgrowth syndrome, whose clinical manifestations typically include macrosomia (large body size), macroglossia (large tongue), omphalocele (intestinal hernia through the umbilicus), organomegaly (enlarged organs), hemihypertrophy (overgrowth of one side of the body), neonatal hypoglycemia (low blood sugar in the newborn period), and ear creases and ear pits. Patients with this syndrome have an increased risk of embryonal malignancies such as Wilms tumor, hepatoblastoma, neuroblastoma, adrenocortical cancer, and rhabdomyosarcoma. The majority (about 85%) of patients with Beckwith-Wiedemann syndrome (BWS) have no family history of it while a minority (about 15%) of patients have a family history with autosomal dominant transmission of the syndrome.
Emotional child abuse:  The third most frequently reported form of child abuse (after child neglect and physical child abuse), accounting for 17% of all cases of child abuse. It is likely that emotional child abuse is greatly underreported, since it can be difficult to detect and difficult to document. Emotional child abuse includes acts of commission or omission by the parents and other caregivers that could cause the child to have serious behavioral, emotional, or mental disorders. In some instances of emotional child abuse, the acts of parents or other caregivers alone, without any harm yet evident in the child's behavior or condition, are sufficient to warrant the intervention of child protective services. For example, the parents/caregivers may use extreme or bizarre forms of punishment, such as confinement of a child in a dark closet.
Emotional eating:  The practice of consuming large quantities of food - usually "comfort" or junk foods - in response to feelings other than hunger. Experts estimate that 75% of overeating is caused by emotions.
Emphysema:  (1) pulmonnary emphysema: A lung condition featuring an abnormal accumulation of air in the lung's many tiny air sacs, a tissue called alveoli. As air continues to collect in these sacs, they become enlarged, and may break, or be damaged and form scar tissue. Emphysema is strongly associated with smoking cigarettes, a practice that causes lung irritation. It can also be associated with or worsened by repeated infection of the lungs, such as is seen in chronic bronchitis. The best response to the early warning signs of emphysema is prevention: stop smoking and get immediate treatment for incipient lung infections. Curing established emphysema is not yet possible. Because patients don't have an adequate amount of space in the lungs to breathe, they gasp for breath, and may not be able to obtain enough oxygen. Those with severe emphysema usually end up using an oxygen machine to breathe. In some cases, medication may be helpful to ease symptoms or to treat infection in already-damaged lungs. (2) non-pulmonary emphysema: The escape of air into other body tissues, for example when this occurs in surgery it is termed surgical emphysema.
Empiric risk:  The chance that a disease will occur in a family based upon experience (past history, medical records, etc.) rather than theory.
Empirical:  Based on experience and observation, rather than systematic logic. Experienced physicians often use empirical reasoning to make diagnoses, based on having seen many cases over the years. Less-experienced physicians are more likely to use diagnostic guides and manuals.
Empirical midwife:  A midwife who has entered the profession as an apprentice to a practicing midwife rather than attending a formal school program.
Empyema:  The presence of pus in the pleural space which is between the outer surface of the lung and the chest wall. Empyema is often a complication of pneumonia caused by bacteria such as Streptococcus pneumonia, Staphylococcus aureusV, or Haemophilus influenza (H. flu) type b. The Greek philosopher, Aristotle, recognized empyema and described the drainage of pus with incision and a metal tube as early as 300 BC.
EMT (Emergency Medical Technician):  A person trained in and expert in the performance of the procedures required in emergency medical care.
Enanthem:  A rash inside the body. An example: the spots in measles (Koplik's spots) inside the mouth that look like a tiny grains of white sand surrounded by a red ring. By contrast, a rash on the outside of the body is called an exanthem. A patient with measles may have both an exanthem and an enanthem.
Enate:  1. As a noun, a relative on the mother's side. 2. As an adjective, related on the mother's side. As opposed to agnate (someone related on the father's side).
Encapsulated:  Confined to a specific area, as for example in the case of a tumor which has not spread and remains inside a fibrous capsule.
Encephalitis:  Inflammation of the brain. Encephalitis occurs, for example, in 1 in 1,000 cases of measles. It may start up to 3 weeks after onset of the measles rash and present with high fever, convulsions, and coma. It usually runs a blessedly short course with full recovery within a week. Or it may eventuate in central nervous system impairment or death. Encephalitis can cause brain damage, which may result in or exacerbate the symptoms of a developmental disorder or mental illness. The form called encephalitis lethargica ("sleeping sickness") results in a set of Parkinson's disease-like symptoms called postencephalitic parkinsonianism. In some cases encephalitis causes death. Treatment of encephalitis must begin as early as possible to avoid potentially serious and life-long effects. Depending on the cause of the inflammation, this may include antibiotics, anti-viral medications, and anti-inflammatory drugs. If brain damage results from encephalitis, therapy (such as physical therapy or cognitive restoration therapy) may help patients regain lost functions.
Encephalomyelitis:  Inflammation of both the brain and the spinal cord. Encephalomyelitis can be caused by a variety of conditions that lead to inflammation of the brain and spinal cord. Among the common causes of encephalomyelitis are viruses which infect the nervous system. One type of encephalomyelitis, acute disseminated encephalomyelitis, occurs most commonly after an acute viral infection such as measles (rubeola) and is due to be an autoimmune attack upon the nervous system.
Encephalopathic syndrome:  A dangerous condition with symptoms similar to those of neuroleptic malignant syndrome (NMS), of which it may be a variant. It is associated with lithium toxicity.
Encephalopathy:  A general term meaning brain dysfunction.
Encephalopathy, mitochondrial (MELAS):  MELAS is the acronym for Mitochondrial Encephalopathy, Lactic Acidosis, and Strokelike episodes. MELAS is a form of dementia. It is caused by mutations in the genetic material (DNA) in the mitochondria. While most of our DNA is in the chromosomes in the cell nucleus, another important cell structure that carries DNA is the mitochondrion. Much of the DNA within the mitochondrion is used to manufacture proteins that help in the mitochondrion's energy-producing function. As a result of the disturbed function of their cells' mitochondria, patients with MELAS develop brain dysfunction (encephalopathy) with seizures and headaches, as well as muscle disease with a buildup of lactic acid in the blood (lactic acidosis), temporary local paralysis (strokelike episodes), and abnormal thinking (dementia). MELAS is diagnosed by muscle biopsy showing characteristic ragged red fibers. Brain biopsy shows strokelike changes. MELAS affects persons at different times of life, from 4 to 40s. Most patients show symptoms before 20 years old. Patients are managed according to which areas of the body are affected at a particular time. There is no known treatment for MELAS which is progressive and fatal.
Enchondromatosis:  A condition characterized by multiple enchondromas -- benign masses of cartilage growing within bones. The enchondromas can deform and shorten a limb and predispose to a fracture. The condition can be caused by a mutation in the gene for the parathyroid hormone receptor (PTHR1). Also known as Ollier disease.
Encopresis:  Inability to control the elimination of stool (fecal incontinence). Encopresis can have a variety of causes, including inability to control the anal sphincter muscle or gastrointestinal problems, particularly chronic diarrhea and Crohn's disease. Several neurological disorders are also occasionally associated with the symptom of encopresis, particularly in children, including Tourette's syndrome and obsessive-compulsive disorder. Preventive care for encopresis including frequent scheduled toileting, and pads or diapers to prevent embarrassing soiling. Careful cleaning is important to prevent skin breakdown. Treatment of encopresis usually involves treatment of the underlying disorder.
End stage:  The last phase in the course of a progressive disease. As in end-stage liver disease, end-stage lung disease, end-stage renal disease, end-stage cancer, etc. The term "end stage" has come to replace "terminal" because somehow "end stage" seems more scientific and less despairing than "terminal." The only "stage" past "end stage" is usually death or a reprieve from it by a transplant.
End-of-the-road disease:  Guinea worm disease, a parasitic illness caused by infection with the guinea worm (Dracunculus medinensis), the largest parasite known to plague people. Guinea worm disease is also known as Dracunculiasis. It is called end-of-the-road disease because it is not seen in the big cities. Once it infects a person, the guinea worm migrates through their body. It eventually emerges from the body (through the feet in 90% of cases) causing intensely painful edema (swelling), a blister and then an ulcer. Perforation of the skin by the guinea worm, which can be 6 feet long, is accompanied by fever and nausea and vomiting. Infected persons may remain sick for some months. The disease is gotten by drinking water contaminated with the infected intermediate hosts of the parasite, called cyclops. The full-grown guinea worm begins to migrate throughout the infected person's body within about a year after ingestion. In areas where the disease is endemic (pervasive), it typically reappears every year during the agricultural season, with farmers in particular being affected. There are no drugs to treat the disease. Prevention of the disease is based on effective surveillance systems; the provision of safe water including appropriate water supply systems, filtering devices and the chemical treatment of water to eliminate the vector; and health education.
End-stage renal disease (ESRD):  Chronic irreversible kidney failure.
Endarterectomy:  An operation to clean out an artery and restore normal blood flow through the artery. An endarterectomy is basically a "Rotorooter" procedure. It removes diseased material from the inside of an artery, and also removes any occluding atheromatous deposits, the aim being to leave a smooth lining within the vessel, so the blood can flow normally.
Endemic:  Present in a community at all times but in relatively low frequency. Something that is endemic is typically restricted or peculiar to a locality or region. For example, malaria is endemic in some areas of Africa. And traffic in illicit drugs is endemic in some neighborhoods.
Endemic typhus (Murine typhus):  An acute infectious disease with fever, headache, and rash, all quite similar to, but milder than, epidemic typhus, caused by a related microorganism, Rickettsia typhi (mooseri). It is transmitted to humans by rat fleas (Xenopsylla cheopis). The animal reservoir includes rats, mice and other rodents. Murine typhus occurs sporadically worldwide but is more prevalent in congested rat-infested urban areas. Also known as rat-flea typhus or urban typhus of Malaya.
Endocannabinoid:  A marijuana-like substance which acts at specific receptors on the blood vessel wall to produce vasodilation and is abbreviated EC. The system which makes use of hte endocannabanoins is called the endocannabinoid system (ECS) and it tightly regulates neurotransmitter release in a host of neuronal tissues. The ECS is also intimately involved in crosstalk between lymphocytes and synchronizing the timing between uterine receptivity and embryo implantation. The endocannabinoid system is thought to be important in long-term potentiation and memory, and learning of muscular coordination.
Endocardial:  Pertaining to the endocardium, the inside lining of the heart.
Endocardium:  The lining of the interior surface of the heart chambers. The endocardium consists of a layer of endothelial cells and an underlying layer of connective tissue.
Endocervical curettage:  The removal of tissue from the inside of the cervix using a spoon-shaped instrument called a curette.
Endochondral bone:  Any bone that develops in and replaces cartilage. The cartilage is partially or entirely destroyed by the process of calcification. The cartilage is then reabsorbed, leaving bone in its place. Many bones are formed this way, particularly the long bones of the arms, legs, and ribs. "Endochondral" means "within cartilage."
Endocrine:  Pertaining to hormones and the glands that make and secrete them into the bloodstream through which they travel to affect distant organs. The endocrine sites include the hypothalamus, pituitary gland, pineal gland, thyroid, parathyroids, heart (which makes atrial-natriuretic peptide - causing sodium excretion), the stomach and intestines, islets of Langerhans in the pancreas, the adrenal glands, the kidney (which makes renin, erythropoietin, and calcitriol), fat cells (which make leptin). the testes, the ovarian follicle (estrogens) and the corpus luteum in the ovary). Endocrine is as opposed to exocrine. The exocrine glands include the salivary glands, sweat glands and glands within the gastrointestinal tract and as a class of glands they all secrete "outside" the body (even though dome excrete into cavities of the body).
Endocrine gland:  A gland that secretes a substance (a hormone) into the bloodstream. The endocrine glands are "glands of internal secretion."
Endocrinologist:  A physician who specializes in the diagnosis and management of hormonal conditions. Endocrinologists usually have background training in one of a number of different medical fields such as pediatrics, internal medicine, obstetrics and gynecology, and oncology. All medical endocrinologists have an M.D. or an analogous medical degree and some also have a Ph.D. or another advanced science degree.
Endocrinology:  The study of hormones, their receptors, the intracellular signalling pathways they invoke, and the diseases and conditions associated with them.
Endocrinopathy:  One of several specific diseases of any of the endocrine glands and also a general medical term for a hormone problem. For example, hyperthyroidism, hypothyroidism, etc.
Endoderm:  One of the three primary germ cell layers -- the other two are the mesoderm and ectoderm -- in the very early embryo. The endoderm is the innermost of the three layers. It differentiates to give rise first to the embryonic gut and then to the linings of respiratory and digestive tracts and the liver and pancreas.
Endodermal:  Pertaining to the endoderm or to tissues derived from the endoderm.
Endogenous:  Inside. For example, endogenous cholesterol is cholesterol that is made inside the body and is not in the diet.
Endometrial ablation:  Removal of the lining of the womb. Removing the uterine lining decreases menstrual flow or stops it completely. The endometrium is the inner layer of the uterus (womb), the uterine lining which is normally shed monthly in response to the hormonal changes of the menstrual period. Ablation means removal or excision, usually surgically. The word comes from the Latin ablatum meaning to carry away.
Endometrial biopsy:  A procedure for sampling the lining of the uterus (the endometrium). Endometrial biopsy is done to learn the cause of abnormal uterine bleeding (most often), determine the cause of infertility, test for uterine infections, and even monitor the response to certain medications. The procedure can be done in the doctor's office.
Endometrial cancer:  Cancer of the womb (the uterus). Endometrial cancer occurs most often in women between the ages of 55 and 70 years. It accounts for about 6% of cancer in women. Women at elevated risk for endometrial cancer include those who are obese, who have few or no children, who began menstruating at a young age, who had a late menopause, and women of high socioeconomic status. It is thought that most of these risk factors are related to hormones, especially excess estrogen.
Endometrial hyperplasia:  A condition characterized by overgrowth of the lining of the uterus. Hyperplasia means overgrowth. The endometrium is the inner layer of the uterus.
Endometriosis:  In endometriosis, cells that normally grow inside the uterus (womb), instead grow outside the uterus. Endometriosis is very common; the cause -- and why some women have endometriosis and many others do not -- has not been fully fathomed, although there are several prevalent theories; most women with endometriosis have no symptoms; but pelvic pain during menstruation or ovulation is a frequent symptom of endometriosis; endometriosis may be suspected by during a physical examination; it is confirmed by surgery, usually laparoscopy; the available treatment includes medication for pain, hormone therapy, and surgery.
Endometriosis interna:  Also known as adenomyosis (pronounced ad-den-o-mi-o-sis), this is a common benign condition of the uterus in which the endometrium (the mucous membrane lining the inside of the uterus) grows into the myometrium (the uterine musculature located just outside the endometrium). The endometrium and myometrium under normal circumstances live adjacent to one another as discrete neighbors. In adenomyosis, the endometrium trespasses upon the myometrium. The myometrium may respond to this intrusion with muscular overgrowth. If an island of endometrial tissue is contained and circumscribed within the myometrium, it forms a nodule called an adenomyoma (plural: adenomyomata). Adenomyosis is made up of adeno (gland) + myo (muscle) +osis (a condition of) = a condition of glandular tissue (referring to the endometrium) in the muscle (the myometrium). Adenomyosis goes by several other names including endometriosis uterina, adenomyosis uteri and adenomyometritis.
Endometritis:  Inflammation of the endometrium.The endometrium is the inner layer of the womb (uterus).
Endometrium:  The uterine lining; the cells that line the uterus (the womb); the inner layer of the uterus. This tissue is shed monthly in response to the hormonal changes of the menstrual period. The endometrium then grows back and slowly gets thicker and thicker until the next period when it is once again sloughed off.
Endonuclease:  An enzyme that cleaves a nucleic acid (DNA or RNA) at specific internal sites in the nucleotide base sequence.
Endopeptidase:  An enzyme that catalyzes the cleavage of peptide bonds within a polypeptide or protein. Peptidase refers to the fact that it acts on peptide bonds and endopeptidase refers to the fact that these are internal bonds. An exopeptide catalyzes the cleavage of the terminal or penultimate peptide bond, releasing a single amino acid or dipeptide from the peptide chain.
Endoplasmic reticulum:  A structure within cells that is an extension of the nuclear membrane and in which proteins slated to become part of the nuclear membrane are translated, folded and transported.
Endorectal MRI:  An MRI (magnetic resonance imaging) done from inside the rectum. To do such as MRI, a surface coil within an inflated latex balloon can be positioned in the rectum. The MRI is read (interpreted) and specific areas of suspicion are identified. The MRI data can be mapped onto a 3-dimensional model to determine strategy. Screening for prostate cancer is plagued by some unresolved problems. One is what to do when a man is found to have a high level of PSA (prostate-specific antigen), has a biopsy of his prostate, and the biopsy shows no sign of a tumor that might be responsible for the rise in PSA. Endorectal MRI may help in this situation since localizing prostate tumors with MRI appears more accurate than localizing such tumors with ultrasound.
Endorphin:  One of the body's own painkillers, an opioid (morphine-like) chemical produced by the body that serves to suppress pain. Endorphins are manufactured in the brain, spinal cord, and many other parts of the body. They are released in response to neurotransmitters and bind to certain neuron receptors (the same ones that bind opiate medicines). Endorphins act as analgesics (diminishing the perception of pain) and as sedatives. Chemically, endorphins are peptides (amino acid chains that are shorter than proteins) and they are rapidly inactivated by enzymes called peptidases.
Endoscope:  A lighted optical instrument used to get a deep look inside the body and examine organs such as the throat or esophagus. An endoscope can be rigid or flexible. Specialized endoscopes are named depending where they are intended to look. Examples include: cystoscope (bladder), nephroscope (kidney), bronchoscope (bronchi), laryngoscope (larynx + the voice box), otoscope (ear), arthroscope (joint), laparoscope (abdomen), and gastrointestinal endoscopes.
Endoscopic gastrostomy, percutaneous (PEG):  A surgical procedure for placing a feeding tube without having to perform an open laparotomy (operation on the abdomen).
Endoscopic retrograde cholangiopancreatography:  Abbreviated ERCP. A procedure done to diagnose and treat problems in the liver, gallbladder, bile ducts, and pancreas, including gallstones, inflammatory strictures (scars), leaks (from trauma and surgery), and cancer. ERCP combines the use of x-rays and an endoscope (a long, flexible, lighted tube). Through it, the physician can see the inside of the stomach and duodenum and inject dye into the bile ducts and pancreas so they can be seen on x-ray. ERCP takes 30 minutes to 2 hours. Possible complications of ERCP include (inflammation of the pancreas), infection, bleeding, and perforation of the duodenum.
Endoscopic sphincterotomy:  An operation to cut the muscle between the common bile duct and the pancreatic duct. The operation uses a catheter and a wire to remove gallstones or other blockages. Also called endoscopic papillotomy.
Endoscopic ultrasound (EUS):  A procedure that combines endoscopy and ultrasound to obtain images and information about the digestive tract and the surrounding tissue and organs.
Endoscopy:  Endoscopy is a broad term used to described examining the inside of the body using an lighted, flexible instrument called an endoscope. In general, an endoscope is introduced into the body through a natural opening like the mouth. Although endoscopy can include examination of other organs, the most common endoscopic procedures evaluate the esophagus (swallowing tube), stomach, and portions of the intestine.
Endostatin:  Endostatin is a fragment of a protein, collagen 18, found in all blood vessels. This fragment is normally secreted by tumors. It appears to halt the process of developing new blood vessels (angiogenesis) which is necessary to tumor development. Endostatin may, it is hoped, represent a prototype for a new class of agents with which to treat cancer.
Endothelial:  Relating to the endothelium, the layer of flat cells lining the closed spaces of the body such as the inside of blood vessels, lymphatic vessels, the heart, and body cavities. By contrast, the outside layer of cells that covers all the free, open surfaces of the body including the skin and mucous membranes that communicate with the outside of the body is called the epithelium.
Endothelial progenitor cell:  A primitive cell made in the bone marrow that can enter the bloodstream and go to areas of blood vessel injury to help repair damage.The number of endothelial progenitor cells in the blood is a risk factor for vascular disease. Depletion or senescence of endothelial progenitor cells may contribute to blood vessel disease.
Endothelium:  A layer of flat cells lining the closed internal spaces of the body such as the inside of blood vessels and lymphatic vessels (that convey the lymph, a milky fluid) and the heart. By contrast, the outside layer of cells that covers all the free, open surfaces of the body including the skin, and mucous membranes that communicate with the outside of the body is called the epithelium.
Endotherm:  An endotherm is a warm-blooded animal (such as homo sapiens). Another term for us warm-blooded creatures is homeotherm. An endotherm or homeotherm is as opposed to poikilotherm (an organism such as a frog that is cold-blooded) and a stenotherm (a creature that can only survive only within a very narrow temperature range).
Endotracheal tube:  A flexible plastic tube that is put in the mouth and then down into the trachea (the airway). The doctor inserts the tube under direct vision with the help of a laryngoscope. The procedure is called endotracheal intubation. The purpose is to ventilate the lungs.
Endourologist:  A urologist with special expertise in navigating, using endoscopic optical instruments and other tools, inside the kidney, ureter and bladder. Endourologists are specialists in treating diseases of these organs.
Endovascular aneurysm repair (EVAR):  A procedure to repair an aneurysm of the aorta. In EVAR a stent is placed in the aneurysmal area of the aorta. The procedure is similar to the placement of a stent in a coronary artery after angioplasty.
Enediyne:  A very potent and naturally occurring antibiotic that acts by cleaving DNA. The adverse effects of enediynes on cells include mutagenicity (increase mutation), halting mitosis (cell division) by arresting the cell cycle, and inducing apoptosis (programmed cell death).
Enfeeble:  To make feeble or weaken. Years of chronic illness may leave someone enfeebled.
Engagement:  This term in obstetrics refers to the sensation that a pregnant woman feels when the baby drops. This is the time when the presenting (the lowermost) part of the fetus descends and is engaged in the mother's pelvis. Engagement is also called "lightening" because the pregnant woman feels lighter after this event. Engagement (lightening) classically takes place 2 to 3 weeks before labor begins. However, it may not occur until labor starts, particularly in women who have already had two or more babies.
Engram:  An enduring change in the brain postulated to account for the persistence of memory. The term "engram" was coined in 1908 to denote the permanent trace left in the brain by a remembered stimulus, the lasting latent memory engraved into the psyche.
Enhanced external counterpulsation (EECP):  A rather violent, but non-invasive (no cutting involved) out-patient treatment for heart disease and, in particular, for angina (chest pain due to an inadequate supply of oxygen to the heart muscle). EECP is designed to relieve angina by improving perfusion in areas of the heart deprived of an adequate blood supply. EECP uses a device to inflate and deflate a series of compressive cuffs that are wrapped around the calves and lower and upper thighs. The basic principle involved is that of counterpulsation. The cuffs inflate during diastole, the period when the heart muscle relaxes and the chambers fill with blood. The cuffs inflate sequentially from the calves upwards, resulting in increased pressure in the aorta and coronary arteries. Compression of the vascular bed in the legs also increases the return of venous blood to the heart and increases cardiac output. This method depends on mechanical pressure to overinflate and thus stretch the vascular system. Patients are customarily treated with EECP for an hour a day for a total of 35 hours.
Enophthalmos:  Sunken eyeball. (The opposite is exophthalmos.)
Enoxaparin:  A low-molecular-weight version of heparin which acts like heparin as an anticoagulant (anti-clotting) medication. Enoxaparin is used to prevent thromboembolic complications (clots that travel from their site of origin through the blood stream to clog up another vessel). Enoxaparin is also used in the early treatment of blood clots in the lungs (pulmonary embolisms).
ENT:  Abbreviation for ears, nose and throat. A field of medicine also called otolaryngology.
ENT physician:  A medical specialist who is concerned with the diagnosis and treatment of disorders of the head and neck, including particularly the ears, nose, and throat. ENT doctors are also called otolaryngologists.
Enteral:  Pertaining to the small intestine. As in enteral nutrition. Also called enteric.
Enteral nutrition:  A way to provide food through a tube placed in the nose, the stomach, or the small intestine. A tube in the nose is called a nasogastric tube or nasoenteral tube. A tube that goes through the skin into the stomach is called a gastrostomy or percutaneous endoscopic gastrostomy (PEG). A tube into the small intestine is called a jejunostomy or percutaneous endoscopic jejunostomy (PEJ) tube.
Enteric:  Pertaining to the small intestine. Also called (less often) enteral.
Enteric-coated:  Coated with a material that permits transit through the stomach to the small intestine before the medication is released.
Enteritis, Crohn (Crohn Enterocolitis):  Crohn disease involving only the small intestine. Crohn disease is a chronic inflammatory disorder, primarily involving the small and large intestine, but which can affect other parts of the digestive system as well. It is named for the doctor (Burrill Crohn) who first described the disease in 1932. The disease is usually diagnosed in persons in their teens or twenties, but can occur at any point in life. Crohn disease can be a chronic, recurrent condition or can cause minimal symptoms with or even without medical treatment. In mild forms, Crohn disease causes small scattered shallow crater-like areas (erosions) called aphthous ulcers in the inner surface of the bowel. In more serious cases, deeper and larger ulcers can develop, causing scarring and stiffness and possibly narrowing of the bowel, sometimes leading to obstruction. Deep ulcers can puncture holes in the bowel wall, leading to infection in the abdominal cavity (peritonitis) and in adjacent organs. Crohn disease has many forms: Involvement of the large intestine (colon) only is called Crohn colitis or granulomatous colitis, while involvement of the small intestine alone is called Crohn enteritis. The most common part of the small intestine to be affected by Crohn disease is the last portion, called the ileum. Active disease in this area is termed Crohn ileitis. When both the small intestine and the large intestine are involved, the condition is called Crohn enterocolitis (or ileocolitis). Other descriptive terms may be used as well. Abdominal pain, diarrhea, vomiting, fever, and weight loss can be symptoms. Crohn disease can be associated with reddish tender skin nodules, and inflammation of the joints, spine, eyes, and liver. Diagnosis is commonly made by x-ray or colonoscopy. Treatment includes medications that are anti-inflammatories, immune suppressors, or antibiotics. Surgery can be necessary in severe cases. Crohn disease is an area of active research around the world and new treatment approaches are being investigated which have promise to improve the lives of affected patients. Also called reginoal enteritis.
Entero-:  Combining form that refers to the intestine (the gut) as in enterocolitis, enteropathy, and enterovirus. From the Greek word "enteron" for intestine, related to the Greek "enteros" meaning "within." The Greeks considered that what went within the intestine was within the body (even though it is not).
Enterobiasis:  Pinworm infection, an infection caused by a small, white intestinal worm - the pinworm or, more formally, Enterobius vermicularis. The pinworm is about the length of a staple and lives for the most part within the rectum of humans. While an infected person is asleep, female pinworms leave the intestines through the anus and deposit eggs on the skin around the anus. The symptoms of a pinworm infection are caused by the female pinworm laying her eggs. Most symptoms of pinworm infection are mild, and many infected people have no symptoms or, at most , some itching around the anus, disturbed sleep, and irritability. However, if the infection is heavy, these symptoms may be correspondingly more severe and also include loss of appetite, restlessness, and insomnia.
Enterocele:  1. Any hernia containing small intestine. 2. Hernia (protrusion) of the small intestine into the upper wall of the vagina.
Enterococcus:  Bacteria normally found in the feces of people and many animals. Two types of enterococci - Enterococcus faecalis and Enterococcus faecium - occasionally cause human disease, most commonly urinary tract infections and wound infections. Other infections, including those of the blood stream (bacteraemia), heart valves (endocarditis) and the brain (meningitis) can occur in severely ill patients in hospitals. Enterococci also often colonize open wounds and skin ulcers. Enterococci are among the most common antibiotic-resistant bacteria. The first vancomycin-resistant enterococcus (VRE) was found in 1986. Since that time, VRE has become a growing problem. Bacteria resistant to vancomycin are commonly also resistant to a similar antibiotic called teicoplanin, and vice versa.
Enteropathy:  Any pathology (disease) of the intestine.
Enteroplasty:  Surgery on the intestine, especially to enlarge a constricted segment or lengthen a short bowel.
Enteroscopy:  The use of a flexible instrument (a "scope") to examine the small intestine, a very long hollow tube located between the stomach and colon and made up of the duodenum, jejunum, and ileum. The upper parts of the small intestine, the duodenum and jejunum, are usually examined as an extension of upper endoscopy, where the instrument is introduced through the mouth, esophagus and stomach. The lower part of the small intestine, the ileum, is often seen during colonoscopy, after the instrument passes through the rectum and colon. Using both types of enteroscopy, the lining of the small intestine can be examined visually with the option of taking biopsy tissue samples, if need be.
Enterospasm:  A painful, intense contraction of the intestine.
Enterostomal therapist:  A health care specialist trained to help patients care for and adjust to their colostomy.
Enterostomy:  A surgical operation that opens the small intestine and brings it through the abdominal wall to create a new opening (a stoma) to permit intestinal draining. Like a colostomy, an enterostomy is a type of ostomy.
Enterovirus:  A virus that enters the body through the gastrointestinal tract and thrives there, often moving on to attack the nervous system. The polioviruses are enteroviruses. Enteroviruses are small viruses that are made of ribonucleic acid (RNA) and protein. In addition to the three different polioviruses, there are 61 non-polio enteroviruses that can cause disease in humans: 29 Coxsackieviruses (23 Coxsackie A viruses and 6 Coxsackie B viruses), 28 echoviruses, and 4 other enteroviruses. The enteroviruses are second only to the "common cold" viruses, the rhinoviruses, as the most common viral infectious agents in humans. The enteroviruses cause an estimated 10-15 million or more symptomatic infections a year in the United States. All three types of polioviruses have been eliminated from the Western Hemisphere.
Entomology:  The scientific study of insects. The application of entomology to medicine is terme medical entomology.
Entomophobia:  An abnormal and persistent fear of insects. Sufferers experience anxiety even though they realize that most insects pose no threat. To avoid insects, they may frequently clean rooms and carpets, sweep hallways, spray insect-killer or seal off doors and windows. Entomophobia includes acarophobia (mites: scabies) and arachnophobia (spiders). A true insect phobia is defined by a persistent irrational fear of and compelling desire to avoid insects, mites, spiders, or similar phobic objects and significant distress from the disturbance despite recognition by the phobic person that their fear is inappropriate, unreasonable, and excessive. "Entomophobia" is derived from the Greek "entomos" (insect) and "phobos" (fear).
Enucleation:  The surgical removal of an eye. Enucleation is only done under drastic circumstances such as to remove a malignant tumor in the eye or to relieve intolerable pain in a blind eye. Following enucleation, an artificial eye (ocular prosthesis) is implanted as a cosmetic substitute for the real eye.
Enuresis:  Involuntary urination, which may be caused by a variety of factors. These include disorders of the kidneys, bladder, or ureter; and poor control of the muscles that control release of urine. Enuresis is also occasionally associated with neurological disorders, such as Tourette's syndrome, particularly in children. Nighttime (nocturnal) enuresis may be related to any of the above, or may be a symptom of a sleep disorder.
Environmental medicine:  The interactions between risk factors in the environment and human health. Environmental medicine focuses on the causes of disease in an environmental context. The environment creates exposures to many different physical, biological and chemical agents.
Environmental toxicology:  The toxicity and toxicology of environmental pollutants in air, dust, sediment, soil and water, and natural toxins in the environment.
Enzootic:  Endemic in animals. An enzootic disease is constantly present in an animal population, but usually only affects a small number of animals at any one time.
Enzyme:  A protein (or protein-based molecule) that speeds up a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions, converting a specific set of reactants (called substrates) into specific products.
Enzyme defect:  A disorder resulting from a deficiency (or functional abnormality) of an enzyme. In 1902 Archibald Garrod first attributed a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and galactosemia, an error in the metabolism of the sugar galactose.
Enzyme-linked immunosorbent assay (ELISA):  A rapid immunochemical test that involves an enzyme (a protein that catalyzes a biochemical reaction). It also involves an antibody or antigen (immunologic molecules). ELISA tests are utilized to detect substances that have antigenic properties, primarily proteins (as opposed to small molecules and ions such as glucose and potassium). Some of these include hormones, bacterial antigens and antibodies.
Eosinophil:  A type of leukocyte (white blood cell) with coarse round granules of uniform size within its cytoplasm and typically a bilobate (two-lobed) nucleus. Eosinophils are so named because their cytoplasmic granules stain red with the dye eosin. Eosinophils normally constitute 1 to 3% of the peripheral blood leukocytes, at a count of 350 to 650 per cubic millimeter. Also called an eosinophilic leukocyte. The numbers of eosinophils in blood often rise above the normal range with allergic reactions and parasitic infections.
Eosinophilia:  An abnormally high number of eosinophils in the blood. In areas of the world where parasitic diseases are common, they are the usual cause of eosinophilia. In developed nations, eosinophilia is most often due to allergy or, less often to a drug reaction. There are numerous other causes of eosinophilia, but individually they are quite uncommon. Eosinophilia may be primary or secondary. In primary eosinophilia, the increased production of eosinophils is due to an abnormality in a hematopoietic stem cell as, for example, in eosinophilic leukemia. In secondary eosinophilia, the increased production of eosinophils is a reactive process driven by cytokines, as is the case in allergy.
Eosinophilia, Familial:  An autosomal dominant condition characterized by an abnormally high level of eosinophils in the blood. Despite the prolonged eosinophilia, there may be no symptoms. The gene for familial eosinophilia, called EOS, has been mapped to chromosome region 5q31-33.
Eosinophilic fasciitis (Shulman syndrome):  A disease which leads to inflammation and thickening of the skin and fascia (the lining tissue under the skin that covers a surface of underlying tissues). When the fascia is inflamed, the condition is referred to as "fasciitis.") In eosinophilic fasciitis, the involved fascia is inflamed with the eosinophil white blood cells. There is progressive thickening, and often redness and warmth, and hardness of the skin surface.
Eosinophilic meningitis:  Meningitis with a high percentage of eosinophils (a type of white blood cell) in the cerebrospinal fluid (CSF). The usual cause is the parasite Angiostrongylus cantonensis, also known as the rat lungworm. People become infected with this parasite by ingesting its larvae in raw or insufficiently cooked snails, slugs, freshwater prawns, frogs, or fish. Infection may also occur by consumption of fresh produce such as contaminated lettuce. When the larvae are ingested, they penetrate the intestinal tract, go into blood vessels, and eventually reach the meninges (the covering of the brain and spinal cord). The larvae usually die there shortly thereafter. An eosinophilic reaction develops in response to the dying larvae. It is manifested by an outpouring of eosinophils in the CSF. Most cases of eosinophilic meningitis due to A. cantonensis have been reported in SE Asia and the Pacific Basin. However, in 2002 an outbreak of eosinophilic meningitis was reported in the US. The outbreak struck 12 young adults after they had returned from a trip to Jamaica. Symptoms included headache, neck pain, visual disturbances, and hyperesthesias. Nine of the travelers required hospitalization. A case-control study showed that consumption of a Caesar salad at one dinner was strongly associated with the development of the eosinophilic meningitis. Most cases of eosinophilic meningitis due to A. cantonensis are self-limited and resolve without complications. However, neurologic sequelae do develop in some cases, and deaths have been reported from the disease.
Ependymoma:  A type of brain tumor derived from the cells that line the cavities within the ventricles of the brain and the central canal of the spinal cord. Because cerebrospinal fluid (CSF) normally flows through the cerebral ventricles and the central canal of the spinal cord, blockage due to an ependymoma can cause build-up of fluid, pressure on the brain, and hydrocephalus with the associated symptoms of headaches, nausea and vomiting. Next to leukemia and lymphoma, brain tumors are the most common type of cancer in children. Ependymomas account for about 10% of childhood brain tumors. About 60% of intracranial ependymomas in children are diagnosed by age 5. Treatment depends upon the tumor's location and metastatic spread. Ependymomas can metastasize within the central nervous system. In general, the treatment of an ependymoma is surgical resection. When complete resection is not possible, radiation therapy and/or chemotherapy may be done.
Ephedra:  A medicinal herb, known scientifically as Ephedra sinica and Ephedra equisetina, also known as mahuang. Ephedra comes from the dried rhizome and root of the plant. The main active ingredients in ephedra are ephedrine and pseudoephedrine which account for the medicinal properties of the herb. Both ephedrine and pseudoephedrine are central nervous system stimulants that act as decongestants but, in high doses, can raise the blood pressure. Contraindications for taking ephedra include anxiety, hypertension, heart disease, glaucoma, hyperthyroidism, and prostate enlargement. Ephedra can stimulate uterine contractions and so is hazardous during pregnancy. Ephedra was widely promoted as a natural stimulant and appetite suppressant. There were reports of strokes, heart attacks and death in patients with no prior history of vascular disease. The misuse and overdose of ephedra also resulted in seizures and psychosis. Ephedra represented about 5% of all diet supplements sold but about 45% of the adverse events associated with diet supplements in the US. The US Food and Drug Administration first issued warnings against the consumption of dietary supplements that contain ephedra. Then, after the death on Feb. 17, 2003 of a young baseball pitcher who had used ephedra, the FDA proposed labels warning consumers that ephedra had been linked to heart problems and strokes. And, finally, on Dec. 30, 2003 the FDA banned ephedra from the marketplace because of the health risks it posed. While FDA approved medications routinely result in the deaths of hundreds of thousands each year, the possible death of one person results in the banning of a useful natural product from the market. This type of action provokes many people to suspect economic and political connections with the drug industry affect FDA policy.
Ephelis:  A form of freckle. A flat red or light-brown spot on the skin that typically appears during the sunny months and fades in the winter. They are most often found in people with light complexions and in some families, they are an hereditary trait. The regular use of sunscreen during times of sun exposure helps to suppress the appearance of the ephelis-type freckle. Ephelis is Greek for freckle. The plural is ephelides.
Epicanthal fold:  A fold of skin that comes down across the inner angle (canthus) of the eye. The epicanthal fold is more common in children with Down syndrome and other birth defects than normal children and so is of value in diagnosis. Although some dictionaries state that this eye fold is found in peoples of Asian origin, this is not true. The normal Asian eyefold is continuous with the lower edge of the upper eyelid and actually appears distinctly different than a true epicanthal fold.
Epicardium:  The inner layer of the pericardium, a conical sac of fibrous tissue that surrounds the heart and the roots of the great blood vessels. The pericardium has outer and inner coats. The outer coat is tough and thickened, loosely cloaks the heart, and is attached to the central part of the diaphragm and the back of the sternum (breastbone). The inner coat is double with one layer closely adherent to the heart while the other lines the inner surface of the outer coat with the intervening space being filled with fluid. This small amount of fluid, the pericardial fluid, acts as a lubricant to allow normal heart movement within the chest. The word "pericardium" means around the heart. The outer layer of the pericardium is called the parietal pericardium. The inner part of the pericardium that closely envelops the heart is, as stated, the epicardium; it is also called the visceral pericardium.
Epicondylitis:  An inflammation or damage to the area of an epicondyle of bone. An epicondyle is a projection of bone above a condyle (a rounded prominence at the end of a bone, usually where the bone connects to another bone) where ligaments and tendons are attached. Two common types of epicondylitis are tennis elbow and golfer's elbow. Tennis elbow is also known as lateral epicondylitis, which is an overuse injury to the area of the lateral (outside) epicondyle of the elbow end of the upper arm bone (humerus). Golfer's elbow (medial epicondylitis) is an overuse injury similar to tennis elbow, but in this case the damage occurs in the area of the medial (inside) epicondyle of the upper arm bone.
Epidemic:  The occurrence of more cases of a disease than would be expected in a community or region during a given time period.=20
Epidemic:  hemorrhagic fever: A number of diseases characterized by an abrupt onset of high fever and chills, headache, cold and cough, and pain in the muscles, joints and abdomen with nausea and vomiting followed by bleeding into the kidney and elsewhere.
Epidemic myalgia:  Also known as Bornholm disease, this is a temporary illness that is a result of virus infection. The disease features fever and intense abdominal and chest pains with headache. The chest pain is typically worsened by breathing or coughing. The illness usually lasts from 3 to 14 days. The most common virus causing Bornholm disease is an enterovirus called Coxsackie B. Bornholm disease is also called pleurodynia (because of inflammation of the pleura lining tissue of the lungs).
Epidemic Typhus:  A severe acute disease with prolonged high fever up to 40=B0 C (104=B0 F), intractable headache, and a pink-to-purple raised rash, due to infection with a microorganism called Rickettsia prowazekii. Among the other signs and symptoms of the disease are cough, dyspnea (difficulty breathing), vomiting, splenomegaly (enlargement of the spleen), hypotension (low blood pressure), and neurologic abnormalities including seizures, coma, and mental confusion. R. prowazekii is found worldwide. It is transmitted by the human body louse (Pediculus humanus corporis). The lice become infected on typhus patients and transmit the illness to other people. The mortality rate from epidemic typhus increases with age. Over half of untreated persons age 50 or more die but people of all ages can perish of the disease. Anne Frank died of epidemic typhus in the Bergen-Belsen concentration camp. The neurologic features gave the disease its name from the Greek word "typhos," which means smoke, cloud, and stupor arising from fever. Epidemic typhus is also known as classic typhus, European typhus, jail fever, louse-borne typhus, and ship fever.
Epidemiologist:  A person engaged in epidemiology (not confined to epidemics).
Epidemiology, classical:  The study of populations in order to determine the frequency and distribution of disease and measure risks.
Epidemiology, clinical:  Epidemiology focused specifically upon patients.
Epidermal:  Pertaining to the epidermis, the outermost layer of the skin.
Epidermal growth factor (EGF):  A polypeptide (small protein) that is a powerful mitogen (meaning that it stimulates cells to enter mitosis, cell division). EGF promotes cell growth and differentiation, is essential in embryogenesis, and is important in wound healing. It is produced by many normal cell types and is made in large amounts by some tumors. The EGF gene is on chromosome 4q25 (whereas the gene for its receptor, EGFR, is on chromosome 7). The kidney is the main source of circulating EGF. EGF is also known as urogastrone (URG).
Epidermal growth factor receptor (EGFR):  A protein found on the surface of cells to which epidermal growth factor (EGF) binds. When EGF attaches to EGFR, it activates the enzyme tyrosine kinase, triggering reactions that cause the cells to grow and multiply. EGFR is found at abnormally high levels on the surface of many types of cancer cells, which may divide excessively in the presence of EGF. The drug Iressa attaches to EGFR and thereby inhibits the attachment of EGF and stops cell division. The gene for EGFR is on chromosome 7p12.3-p12.1. The EGFR molecule has 3 regions -- one projects outside the cell and contains the site for binding EGF; the second is embedded in the cell membrane; and the third projects into the cytoplasm of the cell's interior. EGFR is a kinase that attaches phosphate groups to tyrosine residues in proteins. EGFR is also known confusingly as ErbB1, ErbB, oncogene ErbB, and HER1.
Epidermis:  The upper or outer layer of the two main layers of cells that make up the skin. The epidermis is mostly made up of flat, scale-like cells called squamous cells. Under the squamous cells are round cells called basal cells. The deepest part of the epidermis also contains melanocytes. These cells produce melanin, a pigment which gives the skin its color.
Epidermoid carcinoma:  A type of lung cancer in which the cells are flat and look like fish scales. Also called squamous cell carcinoma.
Epidermolysis bullosa:  One in a group of blistering skin conditions. The skin is so fragile in people with epidermolysis bullosa that even minor rubbing may cause blistering. At times, the person may not be aware of rubbing or injuring the skin even though blisters develop. In severe epidermolysis bullosa, blisters are not confined to the outer skin. They may develop inside the body, in such places as the linings of the mouth, esophagus, stomach, intestines, upper airway, bladder, and the genitals. Most forms of epidermolysis bullosa are evident at birth. This disorder can be both disabling and disfiguring, and some forms may lead to early death. The disease results when skin layers separate after minor trauma. Defects of several proteins within the skin are at fault.=20
Epidermolysis bullosa acquisita (EBA):  A rare autoimmune skin disease with blisters. In epidermolysis bullosa acquisita (EBA) the body attacks its own anchoring fibrils with antibodies. The anchoring filaments (thread-like fibers) are structures that anchor the epidermis to the underlying basement membrane. The destruction of the anchoring fibrils leads to tissue separation and blistering in the upper part of the basement membrane. In some cases, EBA has occurred following drug therapy for another condition; in most cases, the cause is unknown.
Epidermolysis bullosa simplex (EBS):  A blistering skin condition usually inherited as an autosomal dominant disease. The faulty genes are those that provide instructions for producing keratin, a fibrous protein in the top layer of skin. As a result, the skin splits in the epidermis, producing a blister. EBS usually begins with blistering that is evident at birth or shortly afterward. In a localized, mild form of EBS called Weber-Cockayne, blisters rarely extend beyond the feet and hands. In some subtypes of EBS, the blisters occur over widespread areas of the body.
Epididymis:  A structure within the scrotum attached to the backside of the testis. The epididymis is a coiled segment of the spermatic ducts that serves to store, mature and transport spermatozoa between the testis and the vas deferens.
Epidural:  Outside the dura mater, the outermost, toughest, and most fibrous of the three membranes (meninges) covering the brain and the spinal cord. An epidural hematoma is a collection of blood beneath the skull but outside the dura.
Epidural anesthetic:  An anesthetic agent injected into the epidural space, the space outside the dura mater.
Epidural hematoma:  A hematoma between the cranium (skull) and the brain's tissue-like covering, which is known as the dura. Epidural hematoma is usually caused by a full-on blow to the head, and is often associated with a skull fracture. Diagnosis is usually by CAT scan. Treatment is by trepanation: drilling through the skull to drain the excess blood.
Epigastrium:  The part of the abdominal wall above the umbilicus (belly button). The hypogastrium is the part of the abdominal wall below the umbilicus. The abdominal wall can thus be divided into upper and lower halves. Or it can be further divided into quadrants by also drawing a vertical line through the umbilicus - right and left upper quadrants (RUQ and LUQ) and right and left lower quadrants (RLQ and LLQ).
Epigenetic:  Something that affects a cell, organ or individual without directly affecting its DNA. An epigenetic change may indirectly influence the expression of the genome.
Epiglottis:  The flap that covers the trachea during swallowing so that food does not enter the lungs. Not everything in medicine is perfectly logical. The name epiglottis was compounded from "epi-" and "- glottis" from the Greek "glotta" meaning "tongue" since it was once believed that the epiglottis was attached to the tongue!
Epiglottitis, acute:  A very rapidly progressive infection causing inflammation of the epiglottis (the flap that covers the trachea) and tissues around the epiglottis that may lead to abrupt blockage of the upper airway and death. The infection is usually caused by bacteria (such as Hemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, and Streptococci) and is contracted through the respiratory tract. Subsequent downward extension produces what is called cellulitis with marked inflammation of the epiglottis and nearby structures. The inflamed epiglottis mechanically obstructs the airway; the work of breathing increases, and the retention of carbon dioxide and hypoxia (low oxygen) may result. Clearance of secretions is also impaired. These factors may result in fatal asphyxia within a few hours.
Epilation:  Removal of body hair, including the hair root, by means of electrical device, tweezer, or wax. Epilation may be performed by a dermatologist, but is more commonly done for cosmetic purposes by a facial technologist or esthetician. After epilation the skin may be particularly sensitive. Also called depilation.
Epilepsy (seizure disorder):  When nerve cells in the brain fire electrical impulses at a rate of up to four times higher than normal, this causes a sort of electrical storm in the brain, known as a seizure. A pattern of repeated seizures is referred to as epilepsy. Known causes include head injuries, brain tumors, lead poisoning, maldevelopment of the brain, genetic and infectious illnesses. But in fully half of cases, no cause can be found. Medication controls seizures for the majority of patients.
Epilepsy, grand mal:  A form of epilepsy characterized by tonic-clonic seizures. involving two phases -- the tonic phase in which the body becomes rigid, and clonic phase in which there is uncontrolled jerking. Tonic-clonic seizures may or may not be preceded by an aura, and are often followed by headache, confusion, and sleep. They may last for mere seconds, or continue for several minutes. If a tonic-clonic seizure does not resolve or if such seizures follow each other in rapid succession, seek emergency help. The person could be in a life-threatening state known as status epilepticus (literally continuous seizure). Treatment is with anti-seizure medications. Grand mal means big illness in French and is in contrast to another type of epilepsy known as petit mal.
Epilepsy, Jacksonian:  A brief alteration in movement, sensation or nerve function caused by abnormal electrical activity in a localized area of the brain. Seizures of this type typically cause no change in awareness or alertness. They are transient, fleeting, ephemeral. Jacksonian seizures are extremely varied and may involve, for example, apparently purposeful movements such as turning the head, eye movements, smacking the lips, mouth movements, drooling, rhythmic muscle contractions in a part of the body, abnormal numbness, tingling, and a crawling sensation over the skin.
Epilepsy, juvenile myoclonic:  A form of epilepsy that occurs between the ages of eight and 26, most commonly in the teenage years. It is characterized by jerking (myoclonic) movements of the arms and upper torso, without loss of consciousness. Seizures are most likely to occur while awakening from sleep. Many children with this disorder are sensitive to light (photosensitive), and may have myoclonic jerks or seizures when exposed to bright light. Diagnosis is by observation and by EEG. During a myoclonic seizure, polyspike-wave discharges over a normal EEG background are seen. Juvenile myoclonic epilepsy appears to be an inheritable genetic disorder, with the gene located on chromosome 6. Treatment is with anti- seizure medications.
Epilepsy, partial:  A seizure that affects only one part of the brain. Symptoms will depend on which part is affected: one part of the body, or multiple body parts confined to one side of the body, may start to twitch uncontrollably. Partial epilepsy seizures may involve head turning, eye movements, lip smacking, mouth movements, drooling, rhythmic muscle contractions in a part of the body, apparently purposeful movements, abnormal numbness, tingling, and a crawling sensation over the skin. Partial seizures can also include sensory disturbances, such as smelling or hearing things that are not there, or having a sudden flood of emotions. Although the patient may feel confused, consciousness is not lost. Also known as focal or local seizures.
Epilepsy, petit mal:  A form of epilepsy with very brief, unannounced lapses in consciousness. A petit mal seizure involves a brief loss of awareness, which can be accompanied by blinking or mouth twitching. Petit mal seizures have a very characteristic appearance on an electroencephalogram (EEG). Petit mal (little illness in French) seizures are also known as absence seizures. Petit mal seizures take the form of a staring spell: the person suddenly seems to be "absent."
Epilepsy, temporal-lobe:  Epilepsy that is characterized by abnormal electrical activity in the temporal lobe of the brain. This activity does not cause grand mal seizures; rather, it causes unusual behaviors and patterns of cognition. Temporal lobe epilepsy may, for example, cause sudden outbursts of unexpected aggression or agitation, or it may be characterized by aura-like phenomena. The seizures of temporal-lobe epilepsy often start in childhood. Temporal lobe epilepsy is difficult to diagnose because temporal lobe seizures may not show up on an EEG. The diagnosis may instead be made through observation of symptoms or the use of brain imaging technology. Temporal lobe epilepsy may be treated with the same anti-seizure medications that are used for other forms of epilepsy. Surgery is also an option to control seizures and preclude unnecessary disability. Temporal-lobe epilepsy is usually classified as simple or complex partial seizures. Simple partial seizures are characterized by a preserved awareness of self and surroundings (also known as an aura). Patients commonly experience a variety of psychic, gustatory, olfactory, and autonomic symptoms. Complex partial seizures are characterized by impaired awareness. Patients are disabled. They lose awareness and tend to have a motionless stare accompanied by automatisms -- stereotyped, repetitive, involuntary movements such as lip smacking, chewing, picking at objects, scratching, and gesturing.
Epinephrine:  A hormone produced by the medulla (inside) of the adrenal gland. Epinephrine was originally (1898) isolated from the adrenal gland located above (epi-) the kidney ("nephros" in Greek). Technically speaking, epinephrine is a sympathomimetic catecholamine, taht is it causes quickening of the heart beat, strengthens the force of the heart's contraction, opens up the airways (bronchioles) in the lungs and has numerous other effects. The secretion of epinephrine by the adrenal is part of the fight-or-flight reaction. Adrenaline is a synonym of epinephrine and is the official name in the British Pharmacopoeia.
Epiphenomenon:  1. An additional symptom or condition that appears during the course of a disease. A doctor might ask if you have noticed any epiphenomena recently as a way of inquiring as to whether you have experienced additional symptoms or signs of illness. Any occurrence that is accidental, accessory, or incidental to a cause-and-effect relationship. For example, an increase in breast cancer risk with antibiotic usage may be an epiphenomenon if it is not the antibiotic, but the reason for the antibiotic use, namely inflammation, that is associated with breast cancer.
Epiphysis:  The growth area near the end of a bone.
Episclera:  A thin membrane that covers the sclera (the white of the eye).
Episcleritis:  Inflammation of the episclera, a thin membrane that covers the sclera (the white of the eye). Episcleritis is typically benign, easily treated with topical antiinflammatory drops, and usually soon resolved.
Episiotomy:  A surgical procedure for widening the outlet of the birth canal to facilitate delivery of the baby and to avoid a jagged rip of the perineum (the area between the anus and the vulva, the opening to the vagina). During an episiotomy, an incision is made between the vagina and the rectum. The usual cut goes straight down and does not involve the muscles around the rectum or the rectum itself. An episiotomy can decrease the amount of maternal pushing, trauma to the vaginal tissues and expedite delivery of the baby when delivery is necessary quickly. The repair is straightforward and is fairly simple. However, episiotomy is also associated with a higher incidence of extensions or tears into the muscle of the rectum or even the rectum itself which is more difficult to repair and more painful for the mother. The typical healing time for an episiotomy is about 4-6 weeks depending on the size of the incision and the type of suture material used to close the episiotomy.
Epispadias:  Congenital (at birth) malformation in which the opening of th urethra (from whence comes the urinary stream) is on the dorsum (topside) of the penis. Hypospadias is the corresponding malformation in which the opening of the urethra is on the ventral surface (underside) of the penis.
Epistaxis:  Nosebleed. The nose is a part of the body that is very rich in blood vessels and is situated in a vulnerable position on the face. As a result, any trauma to the face can cause bleeding which may be profuse. Nosebleeds can occur spontaneously when the nasal membranes dry out, crust, and crack, as is common in dry climates, or during the winter months when the air is dry and warm from household heaters. People are more susceptible if they are taking medications which prevent normal blood clotting (Coumadin, warfarin, aspirin, or any anti-inflammatory medication). Other predisposing factors include infection, trauma, allergic and non-allergic rhinitis, hypertension, alcohol abuse, and inherited bleeding problems. "Epistaxis" is a Greek word meaning "a dripping," especially of blood from the nose.
Epistaxis, treatment of:  To stop epistaxis (a nosebleed), you should: 1. Pinch all the soft parts of the nose together between your thumb and index finger. 2. Press firmly toward the face - compressing the pinched parts of the nose against the bones of the face. 3. Hold the nose for at least 5 minutes (timed by the clock). Repeat as necessary until the nose has stopped bleeding. 4. Sit quietly, keeping the head higher than the level of the heart; that is, sit up or lie with the head elevated. Do not lay flat or put your head between your legs. 5. Apply ice (crushed in a plastic bag or washcloth) to nose and cheeks. If all this fails, apply compression to the bleed and go to an emergency room immediately.
Epistemic:  Cognitive. Pertaining to cognition, the process of knowing and, more precisely, the process of being aware, knowing, thinking, learning and judging.
Epithelial:   Relating to the epithelium, the outside layer of cells that covers all the free, open surfaces of the body including the skin, and mucous membranes that communicate with the outside of the body.
Epithelial basement corneal dystrophy:  A disorder in which the cornea (the normally clear front window of the eye) shows grayish fingerprint lines, geographic map-like lines, and dots (or microcysts) on examination with a slit-lamp that focuses a high intensity light beam as a slit while the examiner looks at the front of the eye through a magnifying scope. The disorder is usually silent and without symptoms. However, about one patient in ten has recurrent erosion of the cornea that usually begins after the age 30. Conversely, half of patients with recurrent corneal erosions of idiopathic (unknown) origin have this disorder. Under the microscope, a structure called the epithelial basement membrane is abnormal. Hence, the name of epithelial basement corneal dystrophy. The disorder was first described by Cogan and colleagues in 1964 and so is also known as Cogan corneal dystrophy as well as map-dot-fingerprint type corneal dystrophy and microcystic corneal dystrophy.
Epithelial carcinoma:  Cancer that begins in the cells that line an organ.
Epithelium:  The outside layer of cells that covers all the free, open surfaces of the body including the skin, and mucous membranes that communicate with the outside of the body. By contrast the endothelium is the layer of cells lining the closed internal spaces of the body such as the blood vessels and lymphatic vessels (that convey the lymph, a milky fluid) which is derived from the extracellular spaces of the body.
Epitope:  A single antigenic site on a protein against which an antibody reacts.
Epizootic:  An epidemic outbreak of disease in an animal population, often with the implication that it may extend to humans. For example, Rift Valley fever (RVF) primarily affects livestock and can cause disease in a large number of domestic animals -- an "epizootic" -- and the presence of an RVF epizootic can lead to an epidemic among humans who are exposed to diseased animals.
EPO test:  A test of the hormone EPO (erythropoietin) in blood. The EPO level can indicate bone marrow disorders, kidney disease, or EPO abuse. Testing EPO blood levels is of value if:
  • Too little EPO might be responsible for too few red blood cells (such as in evaluating anemia).
  • Too much EPO might be causing too many red blood cells (polycythemia).
  • Too much EPO might be evidence for a kidney tumor.
  • Too much EPO in an athlete suggests EPO abuse.
The patient is usually asked to fast for 8-10 hours (overnight) and sometimes to lie quietly and relax for 20 or 30 minutes before the test. The test requires a routine sample of blood.Epsom salt','Magnesium sulfate. Known as Epsom salt because it was originally extracted from the mineral-rich water of Epsom (England).
Epstein-Barr virus (EBV):  EBV is best known as the cause of infectious mononucleosis ("mono"), colloquially known as Kissing Disease, for obvious reasons. Infection with EBV is characterized by fatigue and general malaise. Infection with EBV is fairly common and is usually transient and minor. However, in some individuals EBV can trigger chronic illness, including immune and lymphoproliferative syndromes. It is a particular danger to people with compromised immune systems, such as from AIDS.
Equinophobia:  An abnormal and persistent fear of horses. Sufferers of equinophobia experience undue anxiety even when a horse is known to be gentle and well trained. They usually avoid horses entirely rather than risk being kicked, bitten or thrown. They may also fear other hoofed animals such as ponies, donkeys and mules. This type of phobia may be triggered by a fall from a horse (which is probably why it is said that, after a fall from a horse, one should get right back on). Also known as hippophobia.
Equol:  A substance produced in the intestine as a metabolite of soybeans and soy foods. Equol is a non-steroidal estrogen that acts as an anti-androgen by blocking the hormone dihydrotestosterone (DHT). Some people are able to produce equol while others cannot. Equol is chemically unique among the isoflavones (a family of phytoestrogens, plant estrogens). It is the major metabolite of the phytoestrogen daidzein, an isoflavone abundant in soybeans and soy foods. Equol was so named because it was first isolated (1932) from the urine of pregnant mares and later (1982) identified in the urine of humans consuming soy foods.
Erb palsy:  A form of brachial plexus palsy in which there is paralysis of the muscles of the upper arm and shoulder girdle due to an injury to the roots of fifth and sixth cervical roots or the upper part of the brachial plexus, a network of spinal nerves that originates in the back of the neck, extends through the armpit, and gives rise to nerves to the upper limb. The brachial plexus is formed by the union of portions of the fifth through eighth cervical nerves and the first thoracic nerve, all of which come from the spinal cord. In Erb palsy, the arm is internally rotated and hangs limply at the side. Erb palsy is also known as Duchenne-Erb palsy, Duchenne-Erb paralysis, Erb paralysis, and Erb's palsy.
Erectile dysfunction (ED):  A common men's health problem characterized by the consistent inability to sustain an erection sufficient for sexual intercourse or the inability to achieve ejaculation, or both. It can involve a total inability to achieve an erection or ejaculation, an inconsistent ability to do so, or a tendency to sustain only very brief erections. Erectile dysfunction is also called impotence, The risk of erectile dysfunction increases markedly with age. It is four-fold higher in men in their 60s compared with those in their 40s according to a study published in the Journal of Urology (2000;163:460-463). Men with less education are also more likely to experience impotence, perhaps due to a less healthy lifestyle, less healthy diet, more alcohol, or less exercise. Physical exercise tends to lessen the risk of impotence. Erectile dysfunction can have emotional causes but most often it is due to a physical problem. The physical causes include diseases (such as diabetes and hypertension), injuries (such as from prostate surgery), side-effects of drugs (such as the protease inhibitors used in HIV therapy), and disorders (such as atherosclerosis) that impair blood flow in the penis. Impotence is treatable in all age groups. Treatments include psychotherapy, vacuum devices, surgery and, most often today, drug therapy. These drugs act by potentiating the formation of nitric oxide which impairs blood flow from the penis while increasing blood flow to the penis. The amino acid arginine also potentiates this effect, but of course you will never hear that information from the drug companies.
Ergophobia:  A persistent fear of work. Sufferers of ergophobia experience undue anxiety about the workplace environment even though they realize their fear is irrational. Their fear may actually be a combination of fears, such fear of failing at assigned tasks, fear of speaking before groups at work, or fear of socializing with co-workers.
Ergot:  Ergot could be called a "cereal killer" for it comes from cereals such as rye and wheat and is quite capable of killing someone. A fungus (Claviceps purpurea) that contaminates rye and wheat produces substances (alkaloids) termed ergotamines. Ergotamines constrict blood vessels and cause the muscle of the uterus to contract. They have been much used and have been very useful for the treatment of migraine. They have also been used and misused as abortifacients (agents of abortion). In excess, however, ergotamines can cause symptoms such as hallucinations, severe gastrointestinal upset, a type of dry gangrene, and a painful burning sensation in the limbs and extremities. Chronic ergot poisoning (ergotism) was rife during the Middle Ages due to the consumption of contaminated rye. Because of the burning pain, it was known as "ignis sacer" (holy fire), "ignis infernalis" (hell's fire) and St. Anthony's fire.
Erotic Jealousy Syndrome:  The persistent delusion of infidelity of a spouse or partner. It affects males and, less often, females. It is characterized by recurrent accusations of infidelity, searches for evidence, repeated interrogation of the partner, tests of their partner's fidelity, and sometime stalking. The syndrome may appear by itself or in the course of paranoid schizophrenia, alcoholism, or cocaine addiction. As in Othello, the play by Shakespeare, the syndrome can be highly dangerous and result in disruption of a marriage, homicide and suicide. The erotic jealousy syndrome was first named the Othello syndrome by the English psychiatrist John Todd (1914-1987) in a paper he published with K. Dewhurst entitled "The Othello Syndrome: a study in the psychopathology of sexual jealousy" (Journal of Nervous and Mental Disorder, 1955, 122: 367). The erotic jealousy syndrome is also known as the Othello syndrome, delusional jealousy, morbid jealousy, Othello psychosis, and sexual jealousy.
Erotomania:  The false but persistent belief that one is loved by a person (often a famous or prominent person), or the pathologically obsessive pursuit of a disinterested object of love. Erotomania can be a symptom of schizophrenia or other psychiatric disorders that are characterized by delusional symptoms. A famous case of Erotomania was John W. Hinckley, Jr. who shot President Reagan to impress actress Jodi Foster. His letter to Foster written two hours before the shooting ended with: "I will admit to you that the reason I'm going ahead with this attempt now is because I just cannot wait any longer to impress you. I've got to do something now to make you understand, in no uncertain terms, that I am doing all of this for your sake! By sacrificing my freedom and possibly my life, I hope to change your mind about me. This letter is being written only an hour before I leave for the Hilton Hotel. Jodie, I'm asking you to please look into your heart and at least give me the chance, with this historical deed, to gain your respect and love. I love you forever, John Hinckley"
Eruptive xanthoma:  The sudden eruption on the skin of crops of pink papules (firm pea-sized bumps) with a creamy center. They may appear on the hands, feet, arms, legs and buttocks. The papules may be pruritic (itchy). Eruptive xanthoma is due to high concentrations of plasma triglycerides, as occurs with uncontrolled diabetes. The xanthomas usually disappear when the underlying condition is treated, as when the diabetes comes under control. Also known as diabetic xanthoma or tuberoeruptive xanthoma.
Erythema:  A redness of the skin resulting from inflammation, for example, as caused by sunburn.
Erythema chronicum migrans:  The classic initial rash of Lyme disease. In the early phase of the illness, within hours to weeks of the tick bite, the local skin develops an expanding ring of unraised redness. There may be an outer ring of brighter redness and a central area of clearing.
Erythema infectiosum (Fifth disease):  An oddly named disease caused by a virus called parvovirus B 19. (In the pre-vaccination era, fifth disease was frequently the "fifth disease" that a child contracted.) . Symptoms include low-grade fever, fatigue, a "slapped cheeks rash," and a rash over the whole body. While the illness is mild in most children, some children with immune deficiency (such as those with AIDS or leukemia) or with certain blood disorders (such as sickle cell anemia or hemolytic anemia) may become seriously ill with fifth disease. Parvovirus B19 can temporarily decrease or halt the body's production of red blood cells, causing anemia. Moreover, fifth disease is of consequence in many adults. About 80% of adults with fifth disease have joint aches and pains (arthritis) which may become long-term with stiffness in the morning, redness and swelling of the same joints on both sides of the body (a "symmetrical" arthritis), most commonly involving the knees, fingers, and wrists. Pregnant women (who have not previously had the illness) should avoid contact with patients who have fifth disease. The fifth disease virus can infect the fetus prior to birth. And, while no birth defects have been reported as a result of fifth disease, it can cause the death of the unborn fetus. The risk of fetal death is 5-10% if the mother becomes infected.
Erythema Multiforme (Stevens-Johnson syndrome):  A serious systemic (bodywide) allergic reaction with a characteristic rash involving the skin and mucous membranes, including the buccal mucosa (inside of the mouth). The disease is due to a hypersensitive (allergic) reaction to one of a number of immunologic stimuli including drugs and infectious agents. Abbreviated SJS.
Erythema nodosum:  An inflammatory reaction deep in the skin characterized by the presence of tender red lumps or nodules ranging in size from 1 to 5 centimeters most commonly located over the shins but occasionally involving the arms or other areas. The causes of erythema nodosum include medications (sulfa-related drugs, birth control pills, estrogens, iodides and bromides), strep throat, cat scratch disease, fungal diseases, infectious mononucleosis, sarcoidosis, Behcet's disease, inflammatory bowel disease (Crohn's disease and ulcerative colitis), and normal pregnancy. In many cases, no cause can be determined. Erythema nodosum may be self-limited and go away on its own in 3 to 6 weeks. If treatment is needed, the underlying condition is treated and simultaneously treatment is directed toward the erythema nodosum. This can include antiinflammatory drugs and cortisone by mouth or injection. Colchicine is sometime used effectively to reduce inflammation.
Erythrasma:  A chronic superficial slowly spreading skin infection, especially in the folds of the body and webs between the toes, caused by a bacterium called Corynebacterium minutissimum. Erythrasma most often affects adults, especially those with diabetes, and people in the tropics. Erythrasma looks like a chronic fungal infection. Scaling, cracks, and slight maceration (softening) typically occur in the toe webs, almost always the 3rd and 4th interspaces. Where the thighs contact the scrotum, sharp-edged patches first appear irregular and pink and later become brown with a fine scale. Erythrasma may also involve the armpits, creases below the breasts, abdominal folds, and perineum, particularly in obese middle-aged women or in patients with diabetes mellitus. Erythrasma can be distinguished from ringworm with a Wood's light (a type of UV light) which causes erythrasma characteristically to fluoresce a coral-red color. The treatment for erythrasma is an antibiotic (such as erythromycin or tetracycline). Antibacterial soaps can also help control the infection. However, recurrence 6 to 12 months later is commonplace.
Erythrocyanosis:  Reddish discoloration and swelling of the limbs in response to cold. Erythrocyanosis is particularly common in children and more common in women than men.
Erythrocyte:  A cell that contains hemoglobin and can carry oxygen to the body. Also called a red blood cell (RBC). The reddish color is due to the hemoglobin. Erythrocytes are biconcave in shape, which increases the cell's surface area and facilitates the diffusion of oxygen and carbon dioxide. This shape is maintained by a cytoskeleton composed of several proteins. Erythrocytes are very flexible and change shape when flowing through capillaries. Immature erythrocytes, called reticulocytes, normally account for 1-2 percent of red cells in the blood.
Erythrodermic psoriasis:  A particularly inflammatory form of psoriasis that often affects most of the body surface. It is the least common form of psoriasis and most commonly appears on people who have unstable plaque psoriasis, where lesions are not clearly defined. The erythrodermic form of psoriasis is characterized by periodic, widespread, fiery redness of the skin. The erythema (reddening) and exfoliation (shedding) of the skin are often accompanied by severe itching and pain. Swelling may also develop.
Erythroleukemia:  A form of acute myeloid leukemia (AML) involving the cells that give rise to the erythrocytes (the red blood cells). In this type of leukemia, the body produces large numbers of abnormal, immature red blood cells. Erythroleukemia is classified as acute nonlymphocytic leukemia (ANLL) of the M6 type.
Erythromelalgia:  Also known as Mitchell's disease (after Silas Weir Mitchell), red neuralgia, or erythermalgia, is a rare disorder in which blood vessels, usually in the lower extremities, are episodically blocked and inflamed. There is severe burning pain and skin redness associated with this blood vessel blockage. The attacks are periodic and are commonly triggered by heat, alcohol consumption, or exertion. Erythromelalgia can occur either as a primary or secondary disorder (i.e. a disorder in and of itself or a symptom of another condition). Secondary erythromelalgia can result from small fiber peripheral neuropathy of any cause, hypercholesterolemia, mushroom or mercury poisoning, and some autoimmune disorders. Primary erythromelalgia is caused by mutation of the voltage-gated sodium channel α-subunit gene SCN9A.
Erythromycin:  Erythromycin is a common antibiotic for treating bacterial infection. Sold under many brand names, including EES, Erycin and Erythromia.
Erythrophobia:  An abnormal and persistent fear of blushing. Sufferers of erythrophobia experience undue anxiety even though they realize their fear is irrational. Their anxiety results from worry about being the focus of attention and the subject of embarrassment. Attempts to suppress blushing often have the opposite effect. Sufferers of erythrophobia tend to avoid social gatherings and workplace projects that require them to interact with, or speak before, groups of co-workers. "Erythrophobia" also can refer to fear of the color red because of what it may symbolize, such as blood.
Erythroplakia:  A reddened patch with a velvety surface found in the mouth.
Erythropoietin (EPO):  A hormone produced by the kidney that promotes the formation of red blood cells in the bone marrow. EPO is a glycoprotein (a protein with a sugar attached to it). Human EPO has a molecular weight of 34,000. The kidney cells that make EPO are specialized and are sensitive to low oxygen levels in the blood. These cells release EPO when the oxygen level is low in the kidney. EPO then stimulates the bone marrow to produce more red cells and thereby increase the oxygen-carrying capacity of the blood. EPO is the prime regulator of red blood cell production. Its major functions are to promote the differentiation and development of red blood cells and to initiate the production of hemoglobin, the molecule within red cells that transports oxygen. The EPO gene has been found on human chromosome 7 (in band 7q21). EPO is produced not only in the kidney but also, to a lesser extent, in the liver. Different DNA sequences flanking the EPO gene act to control kidney versus liver production of EPO. The measurement of EPO in the blood is useful in the study of bone marrow disorders and kidney disease. Normal levels of EPO are 0 to 19 mU/ml (milliunits per milliliter). Elevated levels of EPO can be seen in polycythemia, a disorder in which there is an excess of red blood cells. Lower than normal levels of EPO are seen in chronic renal failure. Using recombinant DNA technology, EPO has been synthetically produced for use in persons with certain types of anemia -- such as anemia due to kidney failure, anemia secondary to AZT treatment of AIDS , and anemia associated with cancer. EPO has been much misused as a performance-enhancing drug in endurance athletes including some cyclists (in the Tour de France), long-distance runners, speed skaters, and Nordic (cross-country) skiers. When misused in such situations, EPO is thought to be especially dangerous (perhaps because dehydration can further increase the viscosity of the blood, increasing the risk for heart attacks and strokes. EPO has been banned by the Tour de France, the Olympics, and other sports organizations.
Erythropoietin test:  A test of the hormone erythropoietin (EPO) in blood. An abnormal level of EPO may mean bone marrow or kidney disease or EPO abuse. Testing EPO blood levels is thus of value if:
  • Too little EPO might be responsible for too few red blood cells (such as in evaluating anemia).
  • Too much EPO might be causing too many red blood cells (polycythemia).
  • Too much EPO might be evidence for a kidney tumor.
  • Too much EPO in an athlete suggests EPO abuse.
  • The patient is usually asked to fast for 8-10 hours (overnight) and sometimes to lie quietly and relax for 20 or 30 minutes before the test. The test requires a routine sample of blood.
Normal levels of EPO are 0 to 19 (some say up to 24) mU/ml (milliunits per milliliter). Subnormal values of EPO are found for example in anemia due to chronic kidney failure. Elevated EPO levels are found for example in polycythemia rubra vera, a disorder characterized by an excess of red blood cells. The correct interpretation of an abnormal EPO level depends on the patient's particular picture.
Eschar:  The scab formed when a wound or skin is sealed by the heat of cautery or burning. Also the dark crusted ulcer (tache noire) at the site of the chigger (mite larva) bite in scrub typhus.
Escherichia coli:  Full term for E. coli, the colon bacillus.
Esophageal cancer:  A malignant tumor of the esophagus. The risk of cancer of the esophagus is increased by long-term irritation of the esophagus, such as from smoking, heavy alcohol intake, and Barrett esophagitis. The risk of esophageal cancer rises with the number of cigarettes smoked per day and the duration of smoking. A history of radiotherapy to the area, such as for the treatment of breast cancer or lymphoma, also predisposes to esophageal cancer. Very small tumors in the esophagus usually do not cause symptoms. As a tumor grows, the most common symptom is difficulty in swallowing. There may be a feeling of fullness, pressure, or burning as food goes down the esophagus. Problems with swallowing may come and go. At first, they may be noticed mainly when the person eats meat, bread, or coarse foods, such as raw vegetables. As the tumor grows larger and the pathway to the stomach becomes narrower, even liquids can be hard to swallow, and swallowing may be painful. Cancer of the esophagus can also cause indigestion, heartburn, vomiting, and frequent choking on food. Because of these problems, weight loss is common. Esophageal cancer can be diagnosed through a barium X-ray study of the esophagus and endoscopy and biopsy of the tumor. Treatment includes chemotherapy and sometimes surgery. The prognosis (outlook) with esophageal cancer is guarded. At the time of the diagnosis, more than 50% of patients have unresectable (unremovable) tumors or evidence of metastases.
Esophageal reflux:  A condition wherein stomach contents regurgitate or back up (reflux) into the esophagus (a long cylindrical tube that transports food from the mouth to the stomach). The food in the stomach is partially digested by stomach acid and enzymes. Normally, the partially digested acid content in the stomach is delivered by the stomach muscle into the small intestine for further digestion. In esophageal reflux, stomach acid content refluxes backwards up into the esophagus, occasionally reaching the breathing passages, causing inflammation and damage to the esophagus, as well as to the lung and larynx (the voice box). The process is medically termed gastroesophageal reflux disease (GERD). 10% of patients with GERD develop a Barrett's esophagus which can increase the risk of cancer of the esophagus.
Esophageal speech:  Speech produced with air trapped in the esophagus and forced out again. People with a laryngectomy (for example, for laryngeal cancer) may be taught to produce esophageal speech.
Esophageal stricture, acute:  A narrowing or closure of the normal opening of the swallowing tube leading to the stomach, usually caused by scarring from acid irritation. Acute, complete obstruction of the esophagus occurs when food (usually meat) is lodged in the esophageal stricture. Patients experience chest pain, and are unable to swallow saliva. Attempts to relieve the obstruction by inducing vomiting at home are usually unsuccessful. Patients with complete esophageal obstruction can breathe, and are not at any risk of suffocation. Endoscopy is usually employed to retrieve the meat and relieve the obstruction.
Esophageal stricture, chronic:  A longstanding narrowing or closure of the normal opening of the swallowing tube leading to the stomach usually caused by scarring by acid irritation resulting in narrowing of the esophagus. This condition is a common complication of chronic gastroesophageal reflux disease (GERD). Several procedures are available for stretching (dilating) the strictures without having to resort to surgery. One of the procedures involves placing a deflated balloon across the stricture at the time of endoscopy. The balloon is then inflated, thereby opening the narrowing caused by the stricture. Another method involves inserting tapered dilators of different sizes through the mouth into the esophagus to dilate the stricture.
Esophageal ulcer:  A hole in the lining of the esophagus corroded by the acidic digestive juices secreted by the stomach cells. Ulcer formation is related to H. pylorus bacteria in the stomach, anti-inflammatory medications, and smoking cigarettes. Ulcer pain may not correlate with the presence or severity of ulceration. Diagnosis is made with barium x-ray or endoscopy. Complications of ulcers include bleeding and perforation. Treatment involves antibiotics to eradicate H. pylorus, eliminating risk factors, and preventing complications.
Esophagectomy:  An operation to remove a portion of the esophagus.
Esophagitis:  Inflammation of the esophagus. The esophagus is that soft tube-like portion of the digestive tract connecting the pharynx with the stomach.
Esophagogastric tamponade:  A procedure in which a balloon is inflated within the esophagus and stomach to apply pressure on bleeding blood vessels, compress the vessels, and stop the bleeding. Used in the treatment of bleeding veins in the esophagus (esophageal varices) and stomach. The balloon used in the esophagus is shaped like a sausage while that in the stomach is rounded. Esophagogastric tamponade is also called balloon tamponade. The word "tamponade" is direct from the French. The French verb "tamponner" means to plug up.
Esophagogastroduodenoscopy:  Also known as EGD or upper endoscopy. A procedure that enables the examiner (usually a gastroenterologist) to examine the esophagus (the swallowing tube), stomach, and duodenum (the first portion of small bowel) using a thin flexible tube (a "scope") that can be looked through or seen on a TV monitor.
Esophagoscopy:  Examination of the esophagus using a thin, lighted instrument.
Esophagram:  A series of x-rays of the esophagus. The x-ray pictures are taken after the patient drinks a solution that coats and outlines the walls of the esophagus. Also called a barium swallow.
Esophagus:  The tube that connects the pharynx (throat) with the stomach. The esophagus lies between the trachea (windpipe) and the spine. It passes down the neck, pierces the diaphragm just to the left of the midline, and joins the cardiac (upper) end of the stomach. In an adult, the esophagus is about 25 centimeters (10 inches) long. When a person swallows, the muscular walls of the esophagus contract to push food down into the stomach. Glands in the lining of the esophagus produce mucus, which keeps the passageway moist and facilitates swallowing. Also known as the gullet or swallowing tube. From the Greek oisophagos, from oisein meaning to bear or carry + phagein, to eat.
Esotropia:  Cross-eyed or, in medical terms, convergent or internal strabismus.
ESR (Erythrocyte Sedimentation Rate):  A blood test that detects and monitors inflammation in the body. It measures the rate at which red blood cells (RBCs) in a test tube separate from blood serum over time, becoming sediment in the bottom of the test tube. The sedimentation rate increases with more inflammation. Also commonly called the sed rate.
Essential:  1. Something that cannot be done without. 2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid. 3. Idiopathic. As in essential hypertension. "Essential" is a hallowed term meaning "We don't know the cause."
Essential fatty acid:  A polyunsaturated fatty acid needed by the body that is synthesized by plants but not by the human body and is therefore a dietary requirement.
Essential fatty acid (EFA):  An unsaturated fatty acid that is essential to human health, but cannot be manufactured in the body. There are three types of essential fatty acids: arachnoidic acid, linoleic acid, and linolenic acid. When obtained in the diet, linoleic acid can be converted to both arachnoidic and linolenic acid. It is commonly found in cold-pressed oils, and is particularly high in oils extracted from cold-water fish and certain seeds. Recent research has explored the role of EFAs in the nervous system health. Supplementation with certain EFOs appears to be useful as a treatment for certain neurological disorders. However, arachnoidic acid may lower the seizure threshold. For that reason, always consult a knowledgeable physician before starting a program of EFA supplementation.
Essential mixed cryoglobulinemia:  A condition in which cryoglobulin proteins, which are a mixture of various antibody types, form for unknown (essential) reasons. Cryoglobulins are abnormal blood proteins that, by definition, have the unusual properties of precipitating from the blood serum when it is chilled (hence the "cryo-") and redissolving upon rewarming. Cryoglobulins are gamma globulins with a molecular weight of approximately 200,000. Cryoglobulins can cause problems by causing the blood to be abnormally "thick" which increases the risk of blood clots forming in the brain (stroke), eyes, and heart, also by Inflammation of blood vessels (vasculitis) which increases the risk of blockage of arteries. Essential mixed cryoglobulinemia is characterized by joint pains and swelling (arthritis), enlargement of the spleen, skin vasculitis with purplish patches, and nerve, kidney and heart disease. Treatment is with medications which reduce inflammation and suppress the immune system. Plasmapheresis, in which the blood's serum is replaced with saline (salt water solution), may be done in severe cases. Cryoglobulinemia can also accompany another disease such as multiple myeloma, dermatomyositis, or lymphoma. Sometimes, small amounts of cryoglobulins are discovered by accident in the lab in a serum sample from someone with no apparent symptoms.
Essential oil:  An oil derived from a natural substance, usually either for its healing properties or as a perfume. Some pharmaceuticals, and many over-the-counter or holistic remedies, are based on or contain essential oils. Examples include products containing camphor or eucalyptus that help relieve congestive coughs, and the essential oils used in the practice of aromatherapy.
Essential tremor:  (Also known as familial tremor, heredofamilial tremor, and hereditary essential tremor.) Uncontrollable shaking (tremor) of the hands and head and sometimes other parts of the body. Essential tremor is the most common of all movement disorders and is estimated to affect 3 to 4 million people in the US. In more than half of cases, essential tremor is inherited in an autosomal dominant manner. In 1997, the ETM1 gene (also called FET1) was mapped to chromosome 3 in a study of Icelandic families while another gene, called ETM2, was mapped to chromosome 2 in a large American family of Czech descent. That two genes for essential tremor have been found on two different chromosomes demonstrates that mutations in various genes may lead to essential tremor. The mainstays of treatment are drugs such as propranolol and primidone. Samuel Adams (1722-1803), the American Revolutionist and beer brewer, and cousin of our second president John Adams suffered from a tremor. The tremor affected his hands, head, and voice. Although mild, the tremor was already manifest when Adams was in his early forties. A prolific writer, Adams experienced progressive difficulty with writing in his fifties and early sixties. By age 71, he was forced to dictate all of his correspondence. His tremor was familial, affecting his daughter Hannah and her children. It has been suggested that Adams suffered from one of the earliest documented cases of essential tremor.
Essential vulvodynia:  A seemingly minor disease of major consequence for a woman's quality of life, it is a condition of unknown cause without a proven mode of treatment. It is chronic, diffuse, unremitting sensation of burning of the vulva - (the female external genital organs including the labia, clitoris, and entrance to the vagina) - a painful sensation which may extend to the perineum, thigh or buttock and is often associated with discomfort in the urethra and rectum. Vulvodynia means, literally, "painful vulva." Essential vulvodynia occurs primarily in postmenopausal women. There are no reliable data on the prevalence of essential vulvodynia. The pain is quite variable. It can vanish as suddenly as it begins. The main finding demonstrable on a medical physical examination is hyperesthesia (extreme sensitivity). There is some evidence that damage to the nerves, particularly the pudendal nerve, supplying this area may play a role. The outlook without treatment or spontaneous remission may be for unceasing pain. Rarely, frequency of urination, stress incontinence, and chronic constipation may also develop. Many treatments have been tried. These include drugs such as amitriptyline (Elavil), nerve blocks (to numb the vulvar nerves), decompression of the pudendal nerve, and biofeedback therapy (to relax pelvic muscles). At present there is insufficient evidence to document any benefit from amitriptyline or pudendal nerve decompression for women with essential vulvodynia. This author suspects mercury damage to afferent nerves and favors toxic heavy metal detoxification as treatment.
Estimated date of confinement (EDC):  The due date or estimated calendar date when a baby will be born.
Estrogen-associated blood clots:  Blood clots are occasional but serious side effects of estrogen therapy. They are dose-related, that is, they occur more frequently with higher doses of estrogen. Estrogen therapy preparations (all of which carry this risk) include:
  • esterified estrogens
  • esterified estrogens and methyltestosterone
  • estradiol
  • estrogens (conjugated) and medroxyprogesterone
  • estrogens conjugated
The brand names of the estrogen therapy preparations carrying this risk include:
  • CLIMARA (estradiol)
  • ESTRACE (estradiol)
  • ESTRADERM (estradiol)
  • ESTRATAB (esterified estrogens)
  • ESTRATEST (esterified estrogens and methyltestosterone)
  • MENEST (esterified estrogens)
  • OGEN (estropipate)
  • PREMARIN (estrogens conjugated)
  • PREMPHASE (estrogens conjugated and medroxyprogesterone)
  • PREMPRO (estrogens conjugated and medroxyprogesterone)
Cigarette smokers on estrogen therapy are at a higher risk than non-smokers for blood clots. Therefore, patients requiring estrogen therapy are strongly encouraged to quit smoking.
Ethmoid bone:  An irregularly shaped, spongy bone that provides the floor of the front part of the skull and the roof of the nose. The ethmoid bone consists of two masses of thin plates enclosing air cells and looks like a sieve. From the Greek ethmos, sieve + eidos, resemblance = like a sieve.
Ethmoid sinus:  A collection of air cells within the ethmoid bone, a spongy bone which makes up the front of the floor of the skull and the roof of the nose. From the Greek ethmos, sieve + eidos, resemblance = like a sieve.
Ethyl acrylate:  A substance used in making latex paints and textiles. The US government removed ethyl acrylate from its list of potential cancer-causing agents in 2000. Although ethyl acrylate induces tumors in animals, it only does so when the chemical is given by mouth at such high concentrations that there is severe persistent injury to the stomach. Comparable "significant chronic human oral exposure to (comparably) high concentrations of ethyl acrylate" was deemed by the government to be "unlikely."
Ethylene glycol poisoning:  Poisoning from ethylene glycol (a clear, colorless, odorless liquid with a sweet taste) that can produce dramatic and dangerous toxicity. Ethylene glycol is found most commonly in antifreeze, automotive cooling systems, and hydraulic brake fluid. In an industrial setting it is also used as a solvent and in a variety of processes. Many cases of ethylene glycol poisoning are due to the accidental ingestion of it by children. They may take in large amounts since the substance tastes good. Alcoholics may also drink it as a substitute for alcohol (ethanol). Ethylene glycol is itself relatively nontoxic. However, it is metabolized (changed) in the body by the enzyme alcohol dehydrogenase into glycolic acid, glyoxylic acid and oxalic acid, which are highly toxic compounds. Renal failure, acidosis and hypocalcemia may follow the intake of ethylene glycol. There can be widespread tissue injury in the kidney, brain, liver, and blood vessels. The result can be fatal. The traditional treatment of ethylene glycol poisoning has been ethanol which competes for the attention of the enzyme (as a competitive substrate of alcohol dehydrogenase) and hemodialysis which removes ethylene glycol and its toxic metabolites from the blood. A new alcohol dehydrogenase inhibitor, fomepizole (brand name: Antizol), was approved in 1997 for the treatment of ethylene glycol poisoning in patients at least 12 years old. It has also been used successfully with younger children.
Ethylene oxide:  A chemical widely used in the health care industry to sterilize medical devices and also used to make other chemicals. In the year 2000 the US government upgraded ethylene oxide to the status of a "known human carcinogen." There is an increased risk for leukemia and non-Hodgkin's lymphoma in workers exposed to ethylene oxide.
Eugenics:  Literally, meaning normal genes, eugenics aims to improve the genetic constitution of the human species by selective breeding. The use of Albert Einstein's sperm to conceive a child (by artificial insemination) would represent an attempt at positive eugenics. The Nazis notoriously engaged in negative eugenics by genocide. The practice of eugenics was first legally mandated in the United States in the state of Indiana, resulting in the forcible sterilization, incarceration, and occasionally euthanasia of the mentally or physically handicapped, the mentally ill, and ethnic minorities (particularly people of mixed racial heritage), and the adopting out of their children to non-disabled, Caucasian parents. Similar programs spread widely in the early part of the twentieth century, and still exist in some parts of the world. It is important to note that no experiment in eugenics has ever been shown to result in measurable improvements in human health. In fact, in the best known attempt at positive eugenics, the Nazi "Lebensborn" program, there was a higher-than- normal level of birth defects among the resulting offspring.
Eukaryote:  An organism that consists of one or more cells each of which has a nucleus and other well-developed intracellular compartments. Eukaryotes include all organisms except bacteria, viruses, and certain (blue-green) algae which, by contrast, are prokaryotes. Eukaryotes include fungi, animals, and plants as well as some unicellular organisms. Eukaryotic cells are about 10 times the size of a prokaryote and can be as much as 1000 times greater in volume. The major and extremely significant difference between prokaryotes and eukaryotes is that eukaryotic cells contain membrane-bound compartments in which specific metabolic activities take place. Most important among these is the presence of a nucleus, a membrane-delineated compartment that houses the eukaryotic cell's DNA. It is this nucleus that gives the eukaryote its name. Eukaryote means true nucleus. Eukaryotic organisms also have other specialized structures, called organelles, which are small structures within cells that perform dedicated functions. As the name implies, you can think of organelles as small organs. There are a dozen different types of organelles commonly found in eukaryotic cells.
Euphenics:  Euphenics aims to improve the outcome of a genetic disease by altering the environment. An illustration: people with allergies avoid the items to which they are allergic, thus avoiding the disease states those allergens would induce. The word Literally means "normal appearing,"
Euphoria:  Elevated mood. Euphoria is a desirable and natural occurrence when it results from happy or exciting events, however an excessive degree of euphoria that is not linked to events is characteristic of mental disordes such as hypomania or mania, and abnormal mood states associated with bipolar disorders.
Euploid:  The normal number of chromosomes for a species. For example, in humans, the euploid number of chromosomes is 46 with the notable exception of the unfertilized egg and sperm in which it is 23.
Eustachian tube:  The tube that runs from the middle ear to the pharynx, the function of which is to protect, aerate and drain the middle ear and mastoid sinus. Occlusion of the Eustachian tube leads to otitis media, a particular problem in many children. The Eustachian tube is also called the otopharyngeal tube (because it connects the ear to the pharynx) and the auditory tube (and in Latin, the tuba acustica, tuba auditiva, and tuba auditoria). The Eustachian tube measures only 17-18mm and is horizontal at birth. As it grows to double that length, it grows to be at an incline of 45 degrees in adulthood so that the nasopharyngeal orifice (opening) in the adult is significantly below the tympanic orifice (the opening in the middle ear near the ear drum). The tube bears the name of Bartolomeo Eustachi, a 16th-century (c. 1500-1510 to 1574) Italian physician. With Vesalius and Fallopio (of Fallopian tube fame), Eustachi is considered as one of the three great founders of the study of human anatomy.
Euthanasia:  The word comes straight out of the Greek meaning good death - and for 18th-century writers in England that was what euthanasia meant, a "good" death, a welcome way to depart quietly from life. The commonly understood meaning of euthanasia today is more than the old dictionary definition of dying well, it refers, for example, to the situation when a doctor induces death, with a lethal injection, of a patient who is suffering unrelievably and who has persistently requested the doctor to do so. The Netherlands is the only country in the world where euthanasia is openly practiced. It is not specifically allowed by law, but Dutch law accepts a standard defense from doctors who have adhered to official guidelines. These guidelines hinge on the voluntariness of the request and the unrelievable-ness of the suffering. Under Dutch law euthanasia is the termination of life by a doctor at the express wish of a patient. The request to the doctor must be voluntary, explicit and carefully considered and it must have been made repeatedly. The patient's suffering must be unbearable and without any prospect of improvement. Pain relief administered by a Dutch doctor may shorten a patient's life. As is the case in other countries, this is seen as a normal medical decision in terminal care and not as euthanasia. Euthanasia is a matter of continuing controversy, an issue on which positions range widely and include enthusiastic advocacy, guarded acceptance, outright rejection, and vehement condemnation, equating euthanasia with murder.
Euthyroid:  The state of normal thyroid gland function. As opposed to hyperthyroid (overactive thyroid) and hypothyroid (underactive thyroid).
Evening primrose oil:  A natural source of essential fatty acids (EFOs). Evening primrose oil contains a higher level of arachnoidic acid than some other EFO sources which has been associated with increased seizure activity, so people with seizure disorders may wish to avoid its use.
Event:  A set of outcomes. The use of the term "event" in medicine comes from probability theory. Cardiovascular events might include a heart attack and gastrointestinal events might include a GI bleed.
Evolution:  A theory by one Charles Darwin (1809-82) to explain how life appears as it does on this planet. He posited that some members of a species would develop traits that favor survival and reproduction and slowly become a distinct new species, thus "branching off" from the parent species. Darwin called this process "natural selection," in his book On the Origin of Species in 1859. The theory of evolution depends on a slow progress of form from one species into the next, and proof requires the discovery of intermediate forms between, for example, species A and species B. However, these intermediate forms are curiously absent in the fossil records, so evolutionary theory remains just that: theory. Nevertheless, this theory is widely accepted as fact by the public but widely suspect among real biologists and zoologists.
Ewing's sarcoma:  A type of bone tumor that occurs in children and adolescents named after the American pathologist James Ewing (1866-1943). It occurs most often in the large bones of the arms and legs and the flat bones of the pelvis, spine and ribs. The tumor is caused by a translocation chromosome abnormality that occurs by chance in a single cell which divides to form the malignant cells. Ewing's sarcoma is the second most common type of bone tumor (after osteosarcoma) in children and adolescents. The disease tends to occur between ages 10 and 20 and almost always before age 30. It may metastasize (spread) to bones, the lungs or the bone marrow. Treatment is chemotherapy + radiation therapy. The tumor is typically radiosensitive meaning it responds to radiation therapy. Sometimes surgery is done to remove the original tumor or to remove metastases from the lungs. The overall chance of long-term survival with Ewing's sarcoma is about 60%. Survival is about 75% for patients with localized tumor (particularly if the tumor is located below the elbow or the midcalf) and about 25-30% with tumor that has spread.
Exaggerated startle disease (ESD):  A genetic disorder also known as hyperexplexia in which babies have an exaggerated startle reaction. This disorder was recognized in 1962 when it was described by Drs. Kok and Bruyn as a disease with onset at birth, featuring hypertonia (stiffness), exaggerated startle response, strong brain-stem reflexes (especially head-retraction reflex) and, in some cases, epilepsy. The hypertonia disappeared during sleep and diminished over the first year of life. The startle reflex was sometimes accompanied by sudden stiffness causing the child person to fall suddenly to the ground. There were 29 affected males and females in 6 generations of one family, indicating that the disorder is an autosomal (non-sexlinked) dominant trait. A number of other families have since been found with this disease.
Exanthem:  A rash. The word "exanthem" comes from the Greek exanthema which means "a breaking out."
Exanthem subitum:  Literally a "rash sudden" or sudden rash. It is a viral disease of infants and young children with sudden onset of high fever which lasts several days and then suddenly subsides leaving in its wake a fine red rash. The causative agent is herpesvirus type 6 so the disease is known as Sixth Disease. Also called Pseudorubella, Roseola, Roseola infantilis, and Roseola infantum.
Excimer laser:  A laser that emits very concentrated light in the ultraviolet region of the spectrum. Excimer lasers are used, for example, in ophthalmology to vaporize part of the surface layer of the cornea and thus reshape the cornea to correct refractive errors from myopia (nearsightedness), hyperopia (farsightedness), and astigmatism and also in dermatology to treat psoriasis and vitiligo. "Excimer" is a chemical term that refers to a substance formed by the joining of two atoms or two molecules of the same chemical composition in an excited state; it is an excited dimer or excimer.
Excise:  To cut out. A laser beam may be used to excise a tumor, much as a scalpel is used. The terms excise and resect are not synonymous. Excise implies total removal whereas resect does not.
Excisional biopsy:  A biopsy in which an entire lesion is removed. A excisional biopsy contrasts with an incisional biopsy in which only a sample of tissue is cut out (incised) and removed.
Exclamation point hair:  Exclamation point hair is a key diagnostic finding in a disorder called alopecia areata. This characteristic diagnostic finding of alopecia areata can be found in areas of hair loss and are short broken off hairs that are narrower closer to the scalp and therefore mimic an exclamation point. In some cases a biopsy is necessary for diagnosis.
Excrescence:  An abnormal outgrowth as, for example, a wart. From the Latin ex- (out), + crescere (to grow).
Exemestane:  An oral antiestrogen. Exemestane inhibits the enzyme aromatase in the adrenal glands that produces the estrogens (estradiol and estrone) and thereby lowers their levels. Brand name: Aromasin. This drug is sometimes used in men to treat gynecomastia (developed breasts).
Exercise-induced asthma:  Asthma triggered by vigorous physical activity. Exercise-induced asthma tends to affect children and young adults because of their high level of physical activity, but can occur at any age. Exercise-induced asthma is initiated by the respiratory heat an dcold fluctuations. Rapid rewarming of the bronchi after the cooling effect of rapid breathing, especially in a cold environment, tends to provoke the bronchioles to constrict. Exercise-induced asthma is common. About 85 percent of people who have chronic asthma have an exercise-induced component and about 40 percent of people with seasonal allergies also have exercise-induced asthma, Symptoms worsen during the spring and fall. Acute attacks of exercise-induced asthma can often be avoided by warming up before strenuous activity. Cold dry air is believed to trigger exercise-induced asthma and therefore people proce to this kind of asthma are advised to avoid exercise in a cold dry environment. Indoor swimming may be an ideal form of exercise because the warm, humid air keeps the airways from drying and cooling. Exercise-induced asthma is monitored using a peak-flow meter. This hand-held device measures air flow (how fast air is blown out of the lungs). Patients can use peak-flow meters to measure their own air flow regularly. This allows patients to obtain a much earlier indication of an oncoming attack. Exercise-induced asthma can also be managed by avoiding the offending allergic triggers of asthma and by using medications up to an hour before exercise. Bbronchodilators meds help relax the muscle spasm of the airways, permitting improved air flow. Other medications can be used to prevent the lining of the airways from swelling in response to cold air or allergic triggers. Inhaled cortisone-related medications are sometimes used to reduce inflammation and swelling in the airways. While in the past, athletes were forced out of competition because of exercise-induced asthma, today the condition is manageable in most cases. Exercise-induced asthma is also known as exercise-induced bronchospasm and also as thermally induced asthma.
Exfoliate:  (1) To peal off scaly skin spontaneously. For example, the skin exfoliates from the palms and soles in Reiter's syndrome and Kawasaki's disease. (2) To deliberately wear away the top layer of skin, as many be done gently by applying a topical skin treatment for cosmetic purposes, or by a dermatologist treating acne. In dermatology the most common exfoliating methods are sanding and chemical peels.
Exhibitionism:  ("Flashing": Exhibitionism is characterized by sexually arousing fantasies, urges or behaviors involving exposure of the genitals to an unsuspecting stranger. The individual with this perversion, colloquially called a "flasher," feels a need to surprise, shock or impress his victims. The condition usually is limited to the exposure, with no other advances made, although "indecent exposure" is illegal. Actual sexual contact with the victim is rare, however, the person may masturbate while exposing himself or while fantasizing about exposing himself.
EXIT:  Stands for ex utero intrapartum treatment. Surgery on the fetus may be done after a Cesarean section, but before the cord is cut, so that the fetus is sustained by the mother's placenta and does not have to breath on its own. This method is employed when the fetus suffers from a congenital defect that blocks the airway. By the time the cord is cut and the baby must breath, he or she has a clear airway.
Exocrine gland:  A gland that secretes a substance out through a duct. "Exocrine" refers to the secretion of a substance out through a duct. The exocrine glands include the salivary glands, sweat glands and glands within the gastrointestinal tract. The exocrine glands are the "glands of external secretion" and contrast to the endocrine glands which secrete directly into the blood.
Exogenous:  Originating from outside the organism. HGH taken by needle is exogenous.
Exophthalmos:  Protruding eyeball. A common finding in hyperthyroidism (too much thyroid hormone) of Graves' disease.
Exotropia:  Divergent gaze - one or both eyes deviated laterally. Also called external strabismus or, pejoratively, wall-eyed (like a wall-eyed pike) denoting as if looking at the wall with one eye and straight ahead or at the opposite wall with the other.
Expectorant:  A medication that helps bring up mucus and other material from the lungs, bronchi, and trachea. An example of as expectorant is guaifenesin which promotes drainage of mucus from the lungs by thinning the mucus and also lubricates the irritated respiratory tract.
Expectoration:  A big polysyllabic word for sputum or the act of bringing up and spitting out sputum.
Expiration date:  The date for a drug estimated for its shelf life with proper storage in sealed containers away from harmful and variable factors like heat and humidity. The expiration date of a medicine is based on data, called accelerated stability data, from testing by the manufacturer, that show the product will be good for a particular period of time.
Explant:  1. To transfer tissue from the body and place it in a culture medium for growth. 2. The tissue that is transferred. 3. To remove a device that had been implanted.
Explicit memory:  Memory in which there is a need for conscious effort in order to recall to consciousness. By contrast, in implicit memory there is a lack of conscious effort in the act of recollection. Implicit memory may survive largely unimpaired as a person's powers of explicit memory decline with age or are devastated in Alzheimer disease.
Expressivity:  The consistency of the expression of a genetic disease. For example, Marfan disease shows variable expressivity. Some persons with Marfan's merely have long fingers and toes while others have the full-blown disease with dislocation of the lens and dissecting aneurysm of the aorta.
Exstrophy:  Eversion of a hollow organ at birth. An exstrophic bladder is one that is turned inside out like a rubber glove.
External ear:  There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The external ear is the simplest part of the ear consisting of the pinna or auricle (the visible projecting portion of the ear), the external acoustic meatus (the outside opening to the ear canal), and the external ear canal that leads to the ear drum. In sum, there is the pinna, the meatus and the canal. And the external ear has only to concentrate air vibrations on the ear drum and make the drum vibrate. The external ear is also called the outer ear.
External fixation:  A procedure that stabilizes and joins the ends of fractured bones by a splint or cast. External fixation is as opposed to internal fixation in which the ends of the fractured bone are joined by mechanical devices such as metal plates, pins, rods, wires or screws.
External jugular vein:  The more superficial of the two jugular veins situated on each side of the neck. (The other is the internal jugular vein.) They both drain blood from the head, brain, face and neck and convey it toward the heart. The external jugular vein collects most of the blood from the outside of the skull and the deep parts of the face. It lies outside the sternocleidomastoid muscle and passes down the neck to join the subclavian vein.
Extracellular:  Outside a cell. As opposed to intracellular, meaning within a cell.
Extracorporeal:  Outside the body, in the anatomic sense as in extracorporeal circulation, extracorporeal dialysis, and extracorporeal shock wave lithotripsy, a way of dealing with kidney stones without surgery by focusing a shock wave on the stones to break them up and allow them to pass out with the urine.
Extracorporeal membrane oxygenation (ECMO):  In intensive care medicine, extracorporeal membrane oxygenation (ECMO) is an technique of providing both cardiac and respiratory support oxygen to patients whose heart and lungs are so severely diseased or damaged that they can no longer serve their function. The procedure circulates the blood through an oxygenating system similar to a heart-lung machine which takes over the work of the heart and lungs during open heart surgery. ECMO is most commonly used in NICUs (Neonatal Intensive Care Units) for newborns in pulmonary distress. It is around 75% effective in saving the newborn's life. Newborns can't be placed on ECMO if they are under 4-1/2, thus ruling out the procedure for most premature newborns. Newborn infants are occasionally placed on ECMO due to the lack of a fully functioning respiratory system or other birth defect, but in those cases the survival rates drop to roughly 1/3. ECMO may be used to treat acute respiratory distress syndrome, smoke inhalation injury, or irreversible heart failure. ECMO is only used for limited time because of the high risks of bleeding, clotting, infection and organ failure.
Extracranial:  Outside the cranium, the bony dome that houses and protects the brain, as opposed to intracranial, inside the cranium.
Extracranial hematoma:  A hematoma (a collection of blood) outside the cranium (skull).
Extrapyramidal system:  That part of the nervous system that regulates muscle reflexes. Extrapyramidal side effects are physical symptoms, including tremor, slurred speech, akathisia (inability to stay still), dystonia, anxiety, paranoia, and bradyphrenia (slow thinking), that are primarily associated with improper dosing of or unusual reactions to neuroleptic (anti-psychotic) medications.
Extrasystole:  A premature contraction of the heart that is independent of the normal rhythm of the heart which that arises in response to an impulse in some part of the heart other than the sinoatrial (SA) node. The extrasystole is followed by a pause, as the heart electrical system resets itself and the contraction following the pause is usually more forceful than normal. These more forceful contractions are frequently perceived as palpitations. Systole refers to the time when the left ventricle of the heart is contracting. Extrasystole is also known as extra systole, premature beat, premature contraction, premature systole, premature ventricular (PVB), premature ventricular contraction or PVC.
Extrauterine:  Outside the uterus ss opposed to intrauterine or inside the uterus. For example, normal pregnancies are intrauterine. an extrauterine pregnancy can occur in the ovarian tube or the abdominal cavity and are distinctly abnormal.
Extravasate:  To pass through the walls of a vessel into the surrounding tissues. Blood, lymph, or urine can extravasate. L. extra (out of) + vas (vessel) = out of a vessel.
Extremely low birth weight baby (ELBW):  A baby born very prematurely weighing between 401 and 1000 grams (roughly 1-2 pounds) at birth. ELBW babies are at the lower limits of viability. If an ELBW baby survives, she or he is at elevated risk for neurological abnormalities, hearing and visual impairment, and developmental delay in infancy. The lower a baby's weight at birth, the more likely the child is to be subject to such problems.
Extremities:  The hands and feet.
Extremophil:  An organism that lives under extreme conditions such as Methanococcus jannaschii, a microbe that lives near volcanic hydrothermal vents at extreme depths in the ocean. Means, literally extreme lover, one who thrives in extreme conditions. For example, people who live in Minnesota (where I did my internship) are extremophils.
Extrinsic:  Not an essential or inherent part; coming from the outside. For example, extrinsic forces can be exerted in a car wreck resulting in broken bones.
Extubation:  The removal of a tube from a hollow organ or passageway, often from the airway. The opposite of extubation is intubation. Related words are extubate and intubate.
Exudate:  A fluid rich in protein and cellular elements that oozes out of blood vessels due to inflammation and is deposited in nearby tissues. The altered permeability of blood vessels permits the passage of large molecules and solid matter through their walls. The vessels weep or sweat. Latin exudare, to sweat out, from which exudate is derived. By comparison, a transudate is a fluid that passes through a membrane which filters out much of the protein and cellular elements and yields a watery solution.
Eye color:  The color of the iris. Eye color is polygenic, that is to say determined by multiple genes. The eye color genes include EYCL1 (a green/blue eye color gene located on chromosome 19), EYCL2 (a brown eye color gene) and EYCL3 (a brown/blue eye color gene located on chromosome 15). There are also other genes that influence eye color. The once-held view that blue eye color is a simple recessive trait has long since been shown to be wrong. The genetics of eye color are so complex that almost any parent-child combination of eye colors is possible.
Eye flashing lights:  There are a number of causes of spontaneous flashing light sensations in the eye. A sensation of flashing lights can be caused when the vitreous (the clear, jelly-like substance that fills the middle of the eye) shrinks and tugs on the retina. These flashes of light can appear off and on for several weeks or months. With age, it is more common to experience flashes. They usually do not reflect a serious problem. However, if you notice the sudden appearance of light flashes or a sudden increase in flashing lights, you should see your ophthalmologist immediately to see if the retina has been torn or if there is another cause. Flashes of light that appear as jagged lines or "heat waves" in both eyes, often lasting 10-20 minutes, are different. They are usually caused by migraine, a spasm of blood vessels in the brain. Jagged lines or "heat waves" can also occur without a headache in which case they are termed ophthalmic migraine, or migraine without headache.
Eye pressure test:  A standard eye test using a tonometer that determines the fluid pressure inside the eye. The test is called tonometry. Persistent Increased pressure within the eye is glaucoma, a potentially serious eye problem if not detected and treated promptly. It is recommended that adults over age 40 have tonometry for glaucoma every 3 to 5 years. The pressure inside the eye is measured from the outside. The pressure can be measured without anything touching the eye. The patient looks up close at an instrument that blows a small puff of air into the eye and then uses a special kind of sensor (like a tiny radar detector) to detect the amount of indentation that the air puff causes on the surface of the eye. This indentation is normal and only lasts for a fraction of a second. If patients need to have their eye pressure measured in a setting where this type of machine is not available (as in an emergency room), the pressure can be measured with an instrument resembling a pen, called a pen tonometer. An anesthetic is administered in the form of an eye drop and one end of the instrument is placed on the surface of the eyeball.
Eye Retraction Syndrome (Duane syndrome):  A congenital eye movement disorder in which there is miswiring of the eye muscles, causing some eye muscles to contract when they should not and other eye muscles not to contract when they should. People with the syndrome have a limited (and sometimes no) ability to move the eye outward toward the ear (to abduct the eye) and, in most cases, a limited ability to move the eye inward toward the nose (to adduct the eye). Often, when the eye moves toward the nose, the eyeball also pulls into the socket (retracts), the eye opening narrows and, in some cases, the eye moves upward or downward. Many patients with Duane syndrome turn their face to maintain binocular vision and compensate for improper turning of the eyes. Duane syndrome is unilateral (with only one eye affected) in about 80% of cases. The remaining 20% of cases are bilateral (with both eyes affected) with one eye usually more severely affected than the other.
Eye spots (Floaters):  Blurry spots that drift in front of the eyes but do not block vision. The blur is the result of debris from the vitreous casting a shadow on the retina. The spot is the image formed by a deposit of protein drifting about in the vitreous, the clear jelly-like substance that fills the middle of the eye. Floaters are often described by patients as spots, strands, or little flies. Floaters are usually benign. They can result from a separation of the vitreous gel from the retina. This condition is called a posterior vitreous detachment (PVD). Although a PVD occurs commonly, there are no retinal tears associated with the condition most of the time. It is commonly said that no treatments are available for floaters. However, factually, there are three ophthalmologists in the U.S. who specialize in treatment of floaters with the Yag Laser. Before signing up for such treatment, one should consider the possible risks and weigh those against the possible benefits. This treatment works for some people but it is far from universally successful.
Eyelid myokymia:  Fine continuous contractions of the eyelid muscle, typically involving one of the lower eyelids, less often an upper eyelid. The condition occurs spontaneously, sometimes triggered by stress, fatigue, caffeine or alcohol. In most cases, the condition is benign and ceases of its own accord. Myokemia is continuous involuntary muscle twitchings that give the appearance of wormlike rippling of muscle. The muscle contractions are involuntary (spontaneous) and brief.
Eyetooth:  An upper canine tooth which is immediately lateral to the second incisor. So-named in the mistaken belief that this tooth was connected to a branch of the nerve that supplies the eye.



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