caloric nystagmus


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Related to caloric nystagmus: Caloric testing, lateral nystagmus, vestibular nystagmus

nystagmus

 [nis-tag´mus]
involuntary, rapid, rhythmic movement (horizontal, vertical, rotatory, or mixed, i.e., of two types) of the eyeball. adj., adj nystag´mic.
amaurotic nystagmus nystagmus in the blind or in those with defects of central vision.
amblyopic nystagmus nystagmus due to any lesion interfering with central vision.
aural nystagmus labyrinthine nystagmus.
caloric nystagmus rotatory nystagmus in response to caloric stimuli in the ear, seen during the caloric test.
Cheyne's nystagmus a peculiar rhythmical eye movement resembling Cheyne-Stokes respiration in rhythm.
congenital nystagmus (congenital hereditary nystagmus) nystagmus usually present at birth, usually horizontal and pendular, but occasionally jerky and pendular; the nystagmus may be caused by or associated with optic atrophy, coloboma, albinism, bilateral macular lesions, congenital cataract, severe astigmatism, and glaucoma.
dissociated nystagmus that in which the movements in the two eyes are dissimilar.
end-position nystagmus that occurring only at extremes of gaze.
fixation nystagmus that occurring only on gazing fixedly at an object.
gaze nystagmus nystagmus made apparent by looking to the right or to the left.
labyrinthine nystagmus vestibular nystagmus due to labyrinthine disturbance.
latent nystagmus that occurring only when one eye is covered.
lateral nystagmus involuntary horizontal movement of the eyes.
optokinetic nystagmus nystagmus induced by looking at objects moving across the visual field.
pendular nystagmus nystagmus in which the oscillations of the eyes have an equal rate, amplitude, direction, and type of movement.
positional nystagmus that which occurs, or is altered in form or intensity, on assumption of certain positions of the head.
retraction nystagmus (nystagmus retracto´rius) a spasmodic backward movement of the eyeball occurring on attempts to move the eye; a sign of midbrain disease.
rotatory nystagmus involuntary rotation of the eyes about the visual axis.
secondary nystagmus nystagmus occurring after the abrupt cessation of rotation of the head, caused by the labyrinthine fluid continuing to move.
spontaneous nystagmus that occurring without specific stimulation of the vestibular system.
vertical nystagmus involuntary up-and-down movement of the eyes.
vestibular nystagmus nystagmus due to disturbance of the labyrinth or of the vestibular nuclei; the movements are usually jerky.

ca·lor·ic nys·tag·mus

nystagmus with slow and fast components induced by labyrinthine stimulation with warm or cool water in the ear.
See also: Bárány sign.
Neurology Jerking nystagmus induced by labyrinthic stimulation with warm or cold water instilled in the external auditory canal

ca·lor·ic ny·stag·mus

(kă-lōr'ik nis-tag'mŭs)
Jerky nystagmus induced by labyrinthine stimulation with hot or cold water in the ear.

caloric testing 

A neuro-ophthalmic technique in which cold and warm water is used to stimulate the vestibular system creating horizontal nystagmus (called caloric nystagmus or Barany's nystagmus). Cold water placed in the ear induces a fast-beating vestibular nystagmus with the fast phase moving away from the stimulated ear, while warm water causes the fast phase to move in the direction of the stimulated ear. The mnemonic COWS (cold-opposite, warm-same) is used to describe this effect. By placing the subject at a 30-degree upright position, heated or cooled water stimulates the now vertical horizontal semicircular canals.