| Ascher's aqueous influx phenomenon | The filling of the aqueous vein, which normally carries blood and aqueous, with aqueous, when the junction of the aqueous vein and the recipient vein is partially occluded. Synonym: Ascher's aqueous influx phenomenon. (05 Mar 2000) |
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| Aschner's phenomenon | A decrease in pulse rate associated with traction on extraocular muscles or compression of the eyeball; especially sensitive in children; may produce asystolic cardiac arrest. Synonym: Aschner's phenomenon, Aschner's reflex, Aschner-Dagnini reflex, oculovagal reflex. (05 Mar 2000) |
| Ashman's phenomenon | Aberrant ventricular conduction of a beat ending a short cycle that is preceded by a longer cycle most commonly during atrial fibrillation. (05 Mar 2000) |
| Aubert's phenomenon | A phenomenon in which a bright perpendicular line appears to incline to one side when the observer turns the head to the opposite side in a dark room. (05 Mar 2000) |
| Austin Flint phenomenon | The murmur of relative mitral stenosis during significant aortic regurgitation owing to narrowing of the mitral orifice by pressure of the aortic regurgitant flow on the anterior mitral leaflet. Synonym: Austin Flint murmur. (05 Mar 2000) |
| autoscopic phenomenon | The encountering of an image of oneself, the image being an illusion, a hallucination, or a vivid fantasy. (05 Mar 2000) |
| Babinski's phenomenon | <clinical sign> Extension of the great toe and abduction of the other toes instead of the normal flexion reflex to plantar stimulation, considered indicative of pyramidal tract involvement ("positive" Babinski). Synonym: Babinski reflex, Babinski's phenomenon, great-toe reflex, paradoxical extensor reflex, toe phenomenon. (05 Mar 2000) |
| Bell's phenomenon | A patient with peripheral facial paralysis cannot close the eyelids of the affected side without at the same time moving the eyeball upward and outward. (05 Mar 2000) |
| Bombay phenomenon | A rare recessive trait at a locus that ordinarily manufactures H substance, the precursor from which the A and B phenotypes are elaborated; the mutant causes failure to produce H substance and no matter what the genotype at the ABO locus, the phenotype is O. The Bombay phenomenon is epistatic to the ABO locus. Origin: Bombay, India, where first reported (05 Mar 2000) |
| Bordet-Gengou phenomenon | The phenomenon of complement fixation; when alexin (complement)-containing serum is added to a mixture of bacteria and specific antibody, the alexin is removed (fixed) and is not available to lyse subsequently added erythrocytes sensitised with specific antibody. See: Gengou phenomenon. (05 Mar 2000) |
| breakaway phenomenon | The occurrence, during high-altitude flight, of a sensation of being totally detached from the earth and from other people. (05 Mar 2000) |
| Brucke-Bartley phenomenon | The sensation of glare in response to successive stimuli at frequencies just below the fusion point. (05 Mar 2000) |
| Capgras' phenomenon | <syndrome> The delusional belief that a person (or persons) close to the schizophrenic patient has been substituted for by one or more impostors; may have an organic aetiology. Synonym: Capgras' phenomenon, illusion of doubles. (05 Mar 2000) |
| vacuum disk phenomenon | The appearance of a radiolucent stripe in an intervertebral disk, a manifestation of disk degeneration; a misnomer since there is gas present. (05 Mar 2000) |
| radial phenomenon | Dorsal flexion of the hand occurring involuntarily with palmar flexion of the fingers. (05 Mar 2000) |