R On T Phenomenon: From 1 Different Sources
(in *electrocardiography) the superimposition of an R wave (ventricular *depolarization) on the T wave (ventricular *repolarization) of the preceding heartbeat. It may trigger ventricular fibrillation. See QRS complex; Q–T interval; S–T segment.
the normal outward and upward rotation of the eyes that occurs when the lids are closed, but not during blinking. [Sir C. Bell]... bell’s phenomenon
(Somogyi effect) the phenomenon of high fasting blood-sugar levels in the morning due to an unrecognized hypoglycaemic episode during the night in a person with diabetes. The low blood sugar has resulted in an outpouring of regulatory hormones, such as adrenaline and glucagon, which have raised the blood sugar to supranormal levels by the time of waking. It is important to recognize the cause, since increasing the evening insulin dose, thinking this will bring the morning sugars down, could actually cause a more severe nocturnal hypoglycaemic attack, which the body may not be able to counteract: coma might ensue. The condition can be tested for by measuring blood sugars at the time of the assumed low level.... dawn phenomenon
a collection of symptoms that includes skin rash, conjunctivitis, salivary gland inflammation, and hyperthyroidism due to the intake of high doses of iodine (German Jod, hence the name). [K. A. von Basedow (1799–1854), German physician]... jod–basedow phenomenon
(Kernohan’s syndrome) *hemiplegia that is *ipsilateral to the brain lesion that caused it, due to pressure of the lesion (which is often a haematoma) on surrounding structures in the brain. It is unusual because normally a lesion of the brain causes dysfunction in the *contralateral limbs. [J. W. K. Kernohan (20th century), US pathologist]... kernohan’s phenomenon
(isomorphic response) a phenomenon that occurs in skin diseases, especially psoriasis and lichen planus, in which the characteristic lesions of the disease appear in linear form in response to such trauma as cuts, burns, or scratches. [H. Koebner (1834–1904), German dermatologist]... koebner phenomenon
the rapid alternation between jerky uncontrolled movements (on) and very limited or no movement (off) most often seen in patients with Parkinson’s disease who have been undergoing long-term treatment with levodopa.... on–off phenomenon
perception of the lateral motion of an object in the visual field as having a depth component, due to a relative difference in signal timings between the two eyes. It often occurs spontaneously in several diseases affecting the eyes, such as cataract, *retrobulbar neuritis, and multiple sclerosis. [C. Pulfrich (20th century), German physicist]... pulfrich phenomenon
dizziness induced by exposure to sound. It is seen in various conditions of the inner ear, including *Ménière’s disease and *superior canal dehiscence syndrome. [P. Tullio (1881–1941), Italian biologist]... tullio phenomenon
the worsening of neurological symptoms, including vision, in demyelinating conditions such as multiple sclerosis, when the body becomes overheated in hot weather or by exercise, fever, or saunas and hot tubs. [W. Uhthoff (1853–1927), German ophthalmologist]... uhthoff phenomenon
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