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Ultralow vestibuloocular reflex time constants
Author(s) -
Baloh R. W.,
Beykirch K.,
Tauchi P.,
Yee R. D.,
Honrubia V.
Publication year - 1988
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410230107
Subject(s) - optokinetic reflex , vestibulo–ocular reflex , nystagmus , audiology , eye movement , reflex , gaze , smooth pursuit , medicine , psychology , vestibular system , ophthalmology , neuroscience , psychoanalysis
We report detailed oculomotor studies in 3 patients with central nervous system lesions and markedly decreased time constants (< 2 seconds) of the vestibuloocular reflex (VOR). In 1 patient with Chiari type I malformation, serial measurements over 3 years documented a progressive decrease in the duration of postrotatory nystagmus (100 deg/sec steps, acceleration 140 deg/sec 2 ) until finally there was no sustained nystagmus. At this time, the patient had no response to caloric stimulation or to sinusoidal rotation below 0.2 Hz but normal gain (peak slow‐phase eye velocity/peak chair velocity) above 0.4 Hz (phase lead increased). Gaze holding, saccades, smooth pursuit, and optokinetic nystagmus were normal, but optokinetic‐after‐nystagmus disappeared. The other 2 patients (combined brainstemcerebellar atrophy) had impaired gaze holding, abnormal smooth pursuit and optokinetic nystagmus, and absent optokinetic‐after‐nystagmus. VOR gain to step and high‐frequency sinusoidal stimuli was increased. The neural mechanism that normally prolongs the VOR time constant may have reduced it in our patients.