| Wenckebach phenomenon | Progressive lengthening of conduction time in any cardiac tissue (most often the A-V node or junction) with ultimate dropping of a beat (A-V Wenckebach) or reversion to the initial conduction time (as in QRS Wenckebach). (05 Mar 2000) |
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| Westphal-Piltz phenomenon | A constriction of both pupils when an effort is made to close eyelids forcibly held apart. A variant of the pupil response to near vision. Synonym: Galassi's pupillary phenomenon, Gifford's reflex, lid-closure reaction, orbicularis phenomenon, orbicularis pupillary reflex, Piltz sign, Westphal's pupillary reflex, Westphal-Piltz phenomenon. (05 Mar 2000) |
| Westphal's phenomenon | <clinical sign> Abolition of the patellar tendon reflex, in tabes and certain other diseases of the spinal cord, and occasionally also in brain disease. Synonym: Erb sign, Westphal's phenomenon, Westphal's sign, Westphal-Erb sign. (05 Mar 2000) |
| Wever-Bray phenomenon | The action potentials in the acoustic nerve that correspond to auditory stimuli reaching the cochlea. (05 Mar 2000) |
| constancy phenomenon | In perception, the tendency for brightness, colour, size, or shape to remain relatively perceptually constant despite real changes in colour, size, shape or other conditions of observation. (05 Mar 2000) |
| courvoisier phenomenon | <radiology> In the presence of jaundice: small gall bladder most likely to be cholecystitis / impacted stone (gall bladder chronically inflamed, scarred), large gall bladder most likely to be NEOPLASM (gall bladder intrinsically normal, can dilate), pancreatic head, cholangiocarcinoma (distal common bile duct), ampulla of Vater, duodenal papilla (12 Dec 1998) |
| Pool's phenomenon | In tetany, spasm both of the extensor muscles of the knee and of the calf muscles when the extended leg is flexed at the hip. Synonym: leg phenomenon, Pool-Schlesinger sign, Schlesinger's sign. 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. Synonym: arm phenomenon. (05 Mar 2000) |
| crossed phrenic phenomenon | Hemisection of the cord above the exit of the phrenic nerve paralyzes the ipsilateral half of the diaphragm; if the contralateral phrenic nerve is then sectioned or blocked, contractions on the ipsilateral side are resumed. (05 Mar 2000) |
| Cushing phenomenon | A rise in systemic blood pressure when the intracranial pressure acutely increases, usually in excess of 50% of the systolic arterial pressure. Synonym: Cushing effect, Cushing response. (05 Mar 2000) |
| Hamburger's phenomenon | When CO2 enters the blood from the tissues, it passes into the red blood cell and is converted by carbonate dehydratase to bicarbonate (HCO3-); HCO3- ion passes out into the plasma while Cl- migrates into the red blood cell. Reverse changes occur in the lungs when CO2 is eliminated from the blood. Synonym: Hamburger's phenomenon. (05 Mar 2000) |
| Sanarelli phenomenon | 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 haemorrhages in the lung, liver, and other organs and bilateral cortical necrosis of the kidney. This reaction has no immunological basis. Synonym: Sanarelli phenomenon, Sanarelli-Shwartzman phenomenon. (05 Mar 2000) |
| Sanarelli-Shwartzman phenomenon | 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 haemorrhages in the lung, liver, and other organs and bilateral cortical necrosis of the kidney. This reaction has no immunological basis. Synonym: Sanarelli phenomenon, Sanarelli-Shwartzman phenomenon. (05 Mar 2000) |
| Schellong-Strisower phenomenon | A reduction of the systolic blood pressure, accompanied sometimes by vertigo, on rising from the horizontal to the erect posture. (05 Mar 2000) |
| Schiff-Sherrington phenomenon | 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 phenomenon, i.e., release from an inhibitory influence normally exerted by the spinal segments below the transection. (05 Mar 2000) |
| Schuller's phenomenon | In cases of functional hemiplegia the patient usually turns to the sound side in walking, but to the affected side in case of an organic lesion. (05 Mar 2000) |