Nystagmus

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Related to positional nystagmus: rotary nystagmus, spontaneous nystagmus

nystagmus

[nə′stag·məs]
(medicine)
Involuntary oscillatory movement of the eyeballs.

Nystagmus

 

an involuntary, rapid rhythmic oscillation of the eyeballs. The bilateral form of nystagmus is much more common than the unilateral form. Nystagmus can be lateral, rotatory, vertical, or diagonal, depending on the direction of the oscillations of the eyeball. The condition need not be pathological. For example, rotatory nystagmus can be induced in healthy persons who are revolving in a swivel chair, optokinetic nystagmus can result from fixing the eyes on moving objects, and caloric nystagmus can result when cold or warm water is poured into the ear.

Nystagmus is pathological when it results from a morbid condition in the vestibulocochlear nerve, in the vestibular nuclei of the brainstem, or in the labyrinth of the vestibular apparatus. Nystagmus can also result from a morbid process in the cerebellum, an inflammation of the inner ear, cerebrocranial traumas, infections and toxicoses of the brain, or neoplasms in the brain. In rarer cases, nystagmus is caused by eye diseases. Miner’s nystagmus is an occupational disease in miners who work with a pick under poorly illuminated and poorly ventilated conditions. Because these workers are constantly looking up or to the side, certain eye muscles become strained.

Nystagmus is treated by eliminating the underlying cause. In cases of miner’s nystagmus, the worker is transferred to jobs above the ground.

REFERENCE

Tsimmerman, G. S. Klinicheskaia otonevrologiia. Moscow, 1952.

V. A. KARLOV

References in periodicals archive ?
Low-velocity, sustained, central positional nystagmus (100%) [60]
(5,13,14) patients with horizontal and anterior semicircular canal variants of BPPV and other types of positional nystagmus were excluded.
Electronystagmography revealed minimal positional nystagmus. His alternate binaural bithermal caloric response was normal with a 7% reduced vestibular response (RVR) and a 16% directional preponderance.
Electronystagmography elicited no spontaneous or positional nystagmus. The alternate binaural bithermal caloric test elicited a significant 63% reduced vestibular response (RVR) left.
Electronystagmography (ENG) detected no spontaneous or positional nystagmus. The alternate binaural bithermal caloric test elicited a significant reduced vestibular response (RVR) right of 32%, and the simultaneous binaural bithermal test showed a type 2 RVR right.
Electronystagmography performed elsewhere had detected no spontaneous or positional nystagmus, and the alternate binaural bithermal stimulus had elicited a 10% reduced vestibular response (RVR) right, which is within normal limits.
Electronystagmography elicited no spontaneous or positional nystagmus, and her responses to the alternate binaural bithermal caloric test were normal.
Electronystagmography detected a direction-changing positional nystagmus, with a left-beating nystagmus in the right lateral position and a right-beating nystagmus in the left lateral position.
While under the effects of lorazepam and hydroxyzine HCl (for chronic pruritus), the patient underwent electronystagmography, which revealed no spontaneous or positional nystagmus. Alternate binaural bithermal testing elicited hyperactive responses (>25[degrees]/sec) to the cool stimulus in both ears and to the warm stimulus in the left ear.
Electronystagmography revealed no spontaneous or positional nystagmus. Alternate binaural bithermal testing showed that she had a reduced vestibular response (RVR) on the right and a slightly hypoactive warm response on the right.
In this instance, the direction of the positional nystagmus would suggest a left peripheral vestibular disorder, and the simultaneous binaural bithermal test did not elicit a type 2 response.