- phenomenon
- 1. A symptom; an occurrence of any sort, whether ordinary or extraordinary, in relation to a disease. 2. Any unusual fact or occurrence. [G. phainomenon, fr. phaino, to cause to appear]- adhesion p. a p. manifested by the adherence of antigen-antibody-complement complex to “indicator cells” (microorganisms, platelets, leukocytes, or erythrocytes), the reaction being sensitive and specific for the antigen and antibody in the complex. SYN: erythrocyte adherence p., immune adherence p., red cell adherence p..- AFORMED p. as induced pulsus alternans progresses, a state in which alternating heart depolarizations fail to eject any blood, thus allowing longer diastolic filling; the subsequent beat is then able to produce a significant ejection; at high rates the cardiac minute volume and blood pressure may appear normal. [Alternating, failure of response, mechanical, to electrical depolarization]- Anrep p. homeometric autoregulation of the heart whereby cardiac performance improves as the afterload (systolic wall stress) is increased.- aqueous influx p. 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. SYN: Ascher aqueous influx p..- Arias-Stella p. focal, unusual, decidual changes in endometrial epithelium, consisting of intraluminal budding, and nuclear enlargement and hyperchromatism with cytoplasmic swelling and vacuolation; may be associated with ectopic or uterine pregnancy. SYN: Arias-Stella effect, Arias-Stella reaction.- arm p. SYN: Pool p. (2).- Arthus p. a form of immediate hypersensitivity resulting in erythema, edema, hemorrhage, and necrosis observed in rabbits after injection of antigen to which the animal has already been sensitized and has specific IgG antibodies. The reaction is caused by the inflammation that results from the deposition of antigen-antibody complexes in tissue spaces and in blood vessel walls that activate complement, most of the damage seemingly being due to the polymorphonuclear leukocytes that phagocytize the deposits and release lysosomal enzymes. The p., described by Arthus, was in rabbits, but similar reactions (Arthus-type reactions) are observed in guinea pig s, rats, and dogs, as well as in humans. SEE ALSO: Arthus reaction (2). SYN: Arthus reaction (1).- Aschner p. SYN: oculocardiac reflex.- Ashman p. aberrant ventricular conduction of a beat ending a short cycle that is preceded by a longer cycle most commonly during atrial fibrillation.- Aubert p. a p. 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.- Austin Flint p. 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. SYN: Austin Flint murmur.- autoscopic p. the encountering of an image of oneself, the image being an illusion, a hallucination, or a vivid fantasy.- Bell p. reflex upper deviation of the eye on attempted eye closure; seen with several disorders, including facial mononeuropathies, Guillain-Barré syndrome, and myasthenia gravis.- Bombay p. 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 p. is epistatic to the ABO locus. [Bombay, India, where first reported]- Bordet-Gengou p. the p. of complement fixation; when complement-containing serum is added to a mixture of bacteria and specific antibody, the complement is removed (fixed) and is not available to lyse subsequently added erythrocytes sensitized with specific antibody. SEE ALSO: Gengou p..- breakoff p., breakaway p. the occurrence, during high-altitude flight, of a sensation of being totally detached from the earth and from other people.- Brücke-Bartley p. the sensation of glare in response to successive stimuli at frequencies just below the fusion point.- centralization p. the relatively rapid change in the perceived location of pain, from more peripheral, or distal, to a more proximal, or central, location; commonly occurs during initial evaluation of patients with low back and radiating limb pain; helpful in determining the type and prognosis of physical therapy.- cervicolumbar p. a sense of weakness in the lower extremities on movement of the neck when a lesion is present in the upper portion of the spinal cord; or sensations referred to the neck when a lesion exists in the lower portion of the cord.- cogwheel p. a sudden brief halt in usually smooth respiration or other motor activity. SYN: Negro p..- constancy p. in perception, the tendency for brightness, color, size, or shape to remain relatively perceptually constant despite real changes in color, size, shape or other conditions of observation.- crowding p. a characteristic of amblyopic vision in which vision is better for single optotype presentation than multiple, simultaneous optotype presentation.- Cushing p. a rise in systemic blood pressure when the intracranial pressure acutely increases, usually in excess of 50% of the systolic arterial pressure. SYN: Cushing effect, Cushing response.- Danysz p. reduction of the neutralizing effect of an antitoxin when toxin is mixed with it in divided portions, rather than adding the same total quantity of toxin in one step.- dawn p. abrupt increases in fasting levels of plasma glucose concentrations between 5 and 9 a.m., in the absence of antecedent hypoglycemia; occurs in diabetic patients receiving insulin therapy.- declamping p. shock or hypotension following abrupt release of clamps from a large portion of the vascular bed, as from the aorta; apparently caused by transient pooling of blood in a previously ischemic area. SYN: declamping shock.- déjà vu p. the mental impression that a new experience ( e.g., a scene, sight, sound, or action) has happened before; a common p. in normal persons that may occur more frequently or continuously in certain emotional or organic disorders. Also variously referred to as déjà entendu, déjà éprouvé, déjà fait, déjà pensé, déjà raconté, déjà vécu, or déjà voulu, depending on the experience or sense that is evoked.- Dejerine hand p. clonic contractions of the flexors of the hand (wrist) on tapping the dorsum of the hand or the volar side of the forearm near the wrist; occurs in normal persons but is exaggerated in pyramidal tract lesions. SYN: Dejerine reflex.- Denys-Leclef p. enhanced phagocytosis by leukocytes of microorganisms in the presence of immune serum.- dip p. complete disappearance of ventricular excitability followed by progressive recovery within a few microseconds at the end of excitation; the muscle as a whole repolarizes somewhat inhomogeneously, so that this period is one of special sensitivity to exogenous or endogenous stimuli and reentry.- Donath-Landsteiner p. the hemolysis that results in a sample of blood of a subject with paroxysmal hemoglobinuria when the sample is cooled to around 5°C and then warmed again.- Ehret p. a sudden throb felt by the finger on the brachial artery, as the pressure in the cuff falls during a blood pressure estimation; said to indicate fairly accurately the diastolic pressure.- Ehrlich p. the difference between the amount of diphtheria toxin that will exactly neutralize one unit of antitoxin and that which, added to one unit of antitoxin, will leave one lethal dose free is greater than one lethal dose of toxin; i.e., it is necessary to add more than one lethal dose of toxin to a neutral mixture of toxin and antitoxin to make the mixture lethal (the basis of the L+ dose).- escape p. failure of the pupil in an eye with optic neuritis to maintain constriction as both eyes are alternately stimulated with light.- facialis p. facial spasm produced by light rubbing of the skin or a tap on the zygoma; sometimes percussion above the zygoma causes contraction of the lip only; observed in tetany and sometimes in exophthalmic goiter.- finger p. a sign of organic hemiplegia; with the patient's elbow resting on a table, the patient's wrist is grasped by the examiner's hand, the thumb of which is used to exert pressure on the radial side of the patient's pisiform bone; if the hemiplegia is organic, some or all of the patient's fingers become extended and spread out in a fanlike form. SYN: Gordon sign.- Friedreich p. the tympanitic percussion sound over a pulmonary cavity is slightly raised in pitch on deep inspiration.- Gallavardin p. dissociation between the noisy and musical elements of the ejection murmur of aortic stenosis, the musical element being better heard at the left sternal border and at the cardiac apex while the noisy element is better heard at the aortic area; projection of the aortic stenotic murmur to the low left sternal edge.- gap p. a short period in the cycle of the atrioventricular or intraventricular conduction allowing passage of an impulse which at other times would be blocked in transit. SYN: excitable gap.- Gärtner vein p. fullness of the veins of the arm and hand held below heart level and collapse at a certain variable distance above that level. An unreliable test for venous pressure.- generalized Shwartzman p. when both the primary injection of endotoxin-containing filtrate and the secondary injection are given intravenously 24 hours apart, the animal usually dies within 24 hours after the second inoculation; the characteristic lesions in the rabbit include widespread hemorrhages in the lung, liver, and other organs and bilateral cortical necrosis of the kidney. This reaction has no immunologic basis. SYN: Sanarelli p., Sanarelli-Shwartzman p..- Gengou p. an extension of the Bordet-Gengou p.; noncellular antigens, when mixed with specific antibody, also fix complement.- Glover p. nonrandom ( i.e., haphazard) variation among communities in rates of performing common elective procedures, such as tonsillectomy, hysterectomy, attributable to local variations in medical and surgical practices.- Grasset p. in organic paralysis of the lower extremity, the supine patient can raise either limb separately, but not both together. SYN: Grasset-Gaussel p..- Gunn p. SYN: jaw-winking syndrome.- hip p. SYN: Joffroy reflex.- hip-flexion p. when a hemiplegic attempts to rise from a lying posture, the hip on the paralyzed side is flexed first; the same movement takes place on lying down.- Hoffmann p. excessive irritability of the sensory nerves to electrical or mechanical stimuli in tetany.- Hunt paradoxic p. in dystonia musculorum deformans, if an attempt is made at plantar flexion of the foot when the foot is in dorsal spasm the only response is an increase of the extensor, or dorsal, spasm; if, however, the patient is told to extend the foot that is already in a state of strong dorsal flexion, there will be a sudden movement of plantar flexion; the same p., mutatis mutandis, is observed when there is a condition of strong plantar flexion.- jaw-winking p. SYN: jaw-winking syndrome.- Jod-Basedow p. induction of thyrotoxicosis in a previously euthyroid individual as a result of exposure to large quantities of iodine; occurs most often in areas of endemic iodine-deficient goiter and in patients with multinodular goiter; also can develop following use of iodine-containing agents for diagnostic studies. SYN: iodine-induced hyperthyroidism.- Köbner p. SYN: isomorphic response.- Koch p. 1. the p. of infection immunity; living tubercle bacilli (Mycobacterium tuberculosis) do not cause reinfection when inoculated into tuberculous guinea pig s ( i.e., the animals are “immune” to reinfection) even though the original infections continue to develop and eventually cause death of the animals; 2. rise of temperature and increase of the local lesion, in a tuberculous subject, following an injection of tuberculin.- Kohnstamm p. SYN: aftermovement.- Kühne p. when a constant current is passed through a muscle, an undulation is seen to pass from the positive to the negative pole.- LE p. the formation of LE cells in bone marrow or blood on adding serum from patients with disseminated lupus erythematosus.- leg p. SYN: Pool p. (1).- Marcus Gunn p. SYN: jaw-winking syndrome.- misdirection p. SYN: aberrant regeneration.- Negro p. SYN: cogwheel p..- no reflow p. lack of blood flow, at the microcirculation level, in a damaged area of the brain after reperfusion.- on-off p. a state in the treatment of Parkinson disease by L-dopa, in which there is a rapid fluctuation of akinetic (off) and choreoathetotic (on) movements.- orbicularis p. SYN: eye-closure pupil reaction.- paradoxical diaphragm p. in pyopneumothorax, hydropneumothorax, and some cases of injury, the diaphragm on the affected side rises during inspiration and falls during expiration.- peroneal p. tapping the peroneal nerve below the head of the fibula causes dorsiflexion and abduction of the foot.- Pfeiffer p. the alteration and complete disintegration of cholera vibrios when introduced into the peritoneal cavity of an immunized guinea pig, or into that of a normal one if immune serum is injected at the same time; extended to include bacteriolysis in general.- phi p. an illusion of movement, which occurs by means of successive visual impressions at intervals of 115 to 120 sec; when an occluder is passed from one eye to the other while a small distant light is observed, the light seems to move with the occluder in exophoria, but in an opposite direction in esophoria.- Pool p. 1. in tetany, spasm of both the quadriceps and calf muscles when the extended leg is flexed at the hip; SYN: leg p., Pool-Schlesinger sign, Schlesinger sign. 2. in tetany, contraction of the arm muscles following the stretching of the brachial plexus by elevation of the arm above the head with the forearm extended, resembles the contraction resulting from stimulation of the ulnar nerve. SYN: arm p..- psi p. a p. that includes both psychokinesis and extrasensory perception; the extrasensory mental processes involved in the alleged ability to send or receive telepathic messages.- Pulfrich p. the binocular perception that an small target oscillating in the frontal plane is moving in an elliptical path seen when one eye is covered by a filter or in the presence of a unilateral optic neuropathy.- Purkinje p. in the light-adapted eye, the region of maximal brightness is in the yellow; in the dark-adapted eye, the region of maximal brightness is in the green. SYN: Purkinje effect, Purkinje shift.- Raynaud p. spasm of the digital arteries, with blanching and numbness or pain of the fingers, often precipitated by cold. Fingers become variably red, white, and blue.- rebound p. 1. SYN: Stewart-Holmes sign. 2. generally, any p. in which a variable that has been displaced from its normal state by a disturbing influence temporarily deviates from normal in the opposite direction when the disturbing influence is suddenly removed, before finally stabilizing at its normal state, i.e., a p. involving undershoot; e.g., the subsequent hypoglycemia that may follow injection of glucose, because the initial hyperglycemia caused excessive secretion of insulin.- reclotting p. SYN: thixotropy.- release p. the increased tonus and hyperirritability of muscle-stretch reflexes that occur following damage of the upper portions of the extrapyramidal system.- Riddoch p. ability to appreciate a small moving object in an area of the visual field blind to static objects; particularly associated with occipital lobe lesions.- Ritter-Rollet p. on equal electrical stimulation of motor nerve trunks, the flexor and abductor muscle groups react more readily than the extensors and adductors.- R-on-T p. a premature ventricular (QRS) complex in the electrocardiogram interrupting the T wave of the preceding beat; often predisposes to serious ventricular arrhythmias.- Rumpel-Leede p. appearance of petechiae in an area following application of vascular constriction, such as by a tourniquet, usually after 10 minutes but can appear after shorter period, such as following application of tourniquet to draw blood specimen or use of blood pressure cuff; due to capillary fragility or abnormal platelet numbers (e.g. thrombocytopenia) or function.- Rust p. in cancer or caries of the upper cervical vertebrae, the patient will always support the head by the hands when changing from the recumbent to the sitting posture or the reverse.- Schellong-Strisower p. a reduction of the systolic blood pressure, accompanied sometimes by vertigo, on rising from the horizontal to the erect posture.- Schiff-Sherrington p. when the spinal cord is transected in the midthoracic region or a little lower, the stretch and other postural reflexes of the upper extremity become exaggerated; if the transection is made in the sacral cord, a similar effect is observed in the lower limbs. The effect is regarded as a release p., i.e., release from an inhibitory influence normally exerted by the spinal segments below the transection.- Schüller p. when patients with hemiplegia walk, if the disorder is functional they turn to the unaffected side; if it is organic, they turn to the affected side.- Sherrington p. after the muscles of the leg have been deprived of their motor innervation by sectioning the ventral roots containing fibers for the sciatic nerve, and allowing time for the degeneration of the fibers to occur, stimulation of the sciatic nerve causes slow contraction of the muscles.- Shwartzman p. a rabbit is injected intradermally with a small quantity of lipopolysaccharide (endotoxin) followed by a second intravenous injection 24 hours later and will develop a hemorrhagic and necrotic lesion at the site of the first injection. SEE ALSO: generalized Shwartzman p.. SYN: Shwartzman reaction.- Somogyi p. a rebound p. of reactive hyperglycemia following a period of relative hypoglycemia, which may be subclinical and difficult to detect; the hyperglycemia induces use of more insulin, thus aggravating the problem. SYN: posthypoglycemic hyperglycemia.- Soret p. in a solution kept in a long, upright tube at room temperature, the upper part, being the warmer, is also the more concentrated.- sparing p. SYN: sparing action.- Splendore-Hoeppli p. radiating or annular eosinophilic deposits of host-derived materials, and possibly of parasite antigens, which form around fungi, helminths, or bacterial colonies in tissue.- Staub-Traugott p. the increased rate of removal of loads of glucose given shortly after administration of an initial glucose load.- Strümpell p. dorsal flexion of the great toe, sometimes of the entire foot, in a paralyzed limb when the extremity is drawn up against the body, flexing both knee and hip. SYN: tibial p..- symbiotic fermentation p. “two organisms, neither of which alone produces gas fermentation in certain carbohydrates, may do so when living in symbiosis or when artificially mixed” (Castellani).- Theobald Smith p. a p. observed in guinea pig s that had survived use for diphtheria antitoxin standardization, the animals having been rendered highly susceptible to subsequent inoculation of horse serum.- tibial p. SYN: Strümpell p..- toe p. SYN: Babinski sign (1).- Tournay p. dilation of the pupil in the abducting eye on extreme lateral gaze. This is present in only a small percentage of the normal popupation and has no known association with disease. SYN: Tournay sign.- Tullio p. momentary vertigo caused by any loud sound, notably occurring in cases of active labyrinthine fistula.- two-dimension–three-dimension p. an experience in telescopic endoscopy in which a two-dimensional image appears to be three-dimensional because of the movement of the endoscope in and out of the view of the object.- Tyndall p. the visibility of floating particles in gases or liquids when illuminated by a ray of sunlight and viewed at right angles to the illuminating ray. SYN: Tyndall effect.- vacuum disk p. the appearance of a radiolucent stripe in an intervertebral disk, a manifestation of disk degeneration; a misnomer since there is gas present.- warmup p. progressive diminution of the myotonic response of a muscle, during repeated contraction of the muscle.- Wenckebach p. progressive lengthening of conduction time in any cardiac tissue (most often the AV node or junction) with ultimate dropping of a beat (AV Wenckebach) or reversion to the initial conduction time (as in QRS Wenckebach).
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1) an observable fact or event2 a) an object or aspect known through the senses rather than by thought or intuitionb) a fact or event of scientific interest susceptible of scientific description and explanation* * *
phe·nom·e·non (fə-nomґə-non) pl. phenomґena [Gr. phainomenon that which appears, from phainesthai to appear] any observable occurrence or fact; see also sign and symptom.See also under sign, symptom, and syndrome.
Medical dictionary. 2011.
