| 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) |
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| 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) |
| Schultz-Charlton phenomenon | The specific blanching of a scarlatinal rash at the site of intracutaneous injection of scarlatina antiserum. Synonym: Schultz-Charlton phenomenon. (05 Mar 2000) |
| pseudo-Graefe's phenomenon | Retraction of the upper eyelid on downward movement of the eyes. (05 Mar 2000) |
| Hill's phenomenon | <clinical sign> In aortic insufficiency, greater systolic blood pressure in the legs than in the arms; normal arterial systolic pressure in the leg is 10 to 20 mm of Hg above that in the arm, whereas in aortic insufficiency the difference may be 60 to 100 mm of Hg. Synonym: Hill's phenomenon. (05 Mar 2000) |
| hip-flexion phenomenon | When a hemiplegic attempts to rise from a lying posture, the hip on the paralysed side is flexed first; the same movement takes place on lying down. (05 Mar 2000) |
| hip phenomenon | Twitching of the glutei muscles when firm pressure is made on the nates, in cases of spastic paralysis. Synonym: hip phenomenon. (05 Mar 2000) |
| psi phenomenon | A phenomenon that includes both psychokinesis and extrasensory perception; the extrasensory mental processes involved in the alleged ability to send or receive telepathic messages. (05 Mar 2000) |
| Hoffmann's phenomenon | Excessive irritability of the sensory nerves to electrical or mechanical stimuli in tetany. (05 Mar 2000) |
| Purkinje's phenomenon | <ophthalmology> 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. Synonym: Purkinje effect, Purkinje shift. (05 Mar 2000) |
| hunting phenomenon | An unusual reaction of digital blood vessels exposed to cold; vasoconstriction is alternated with vasodilation in irregular repeated sequences, in an apparent hunting of equilibrium of skin temperature. Synonym: hunting phenomenon. (05 Mar 2000) |
| Sherrington phenomenon | After the muscles of the leg have been deprived of their motor innervation by sectioning the ventral roots containing fibres for the sciatic nerve, and allowing time for the degeneration of the fibres to occur, stimulation of the sciatic nerve causes slow contraction of the muscles. (05 Mar 2000) |
| shot-silk phenomenon | The appearance of numerous wavelike, glistening reflexes, like the shimmer of silk, observed sometimes in the retina of a young person. Synonym: shot-silk phenomenon, shot-silk reflex. (05 Mar 2000) |
| shwartzman phenomenon | A two-stage reaction in which a first encounter with endotoxin produces intravascular fibrin thrombi whose clearance results in reticuloendothelial blockade which prevents the clearance of thrombi caused by a second encounter with endotoxin, resulting in tissue necrosis and/or haemorrhage. In pregnancy gram-negative septicaemia during delivery or abortion may serve as the first or provocative encounter. The phenomenon is non-immunologic and is known to occur only in rabbits and man. (12 Dec 1998) |