The sinusoidal chair rotation test was evaluated in 12 normal subjects. Amplitudes of 30°, 45° and 60°, and frequencies of 0.125Hz, 0.25Hz and 0.5Hz were used. The ocular responses were compared during stepwise increases and decreases in amplitude and frequency of chair rotation. Then 21 patients with cerebellar lesions, 27 patients with both cerebellar and extracerebellar lesions, 12 patients with parkinsonism and 18 control subejects with a history of vertigo or dizziness but no objective neurological signs were tested with sinusoidal chair rotation at an amplitude of 30° and frequencies of 0.5Hz, 0.25Hz and 0.125Hz. The vestibulo-ocular reflex (VOR) gain, cancellation gain, phase shift and visual suppression of caloric nystagmus were determined.
The VOR gain tended to decrease when the chair rotation was increased stepwise. The cancellation gain and phase shift were not influenced by the stepwise increase or decrease in amplitude and frequency of chair rotation.
The VOR gain of patients with cerebellar lesions was significantly increased, but the VOR gain of parkinsonism was not. The cancellation gain of patients with cerebellar lesions was significantly decreased and that of patients with both cerebellar and extracerebellar lesions was decreased even further. The cancellation gain of parkinsonism was also significantly decreased. Visual suppression of caloric nystagmus correlated well with the cencellation gain in patients with cerebellar lesions.
We conclude that sinusoidal chair rotation at an amplitude of 30° or 45° and a frequency of 0.5Hz, 0.25Hz and 0.125Hz in this order can be recommended for the evaluation of the VOR gain and cancellation gain, which provide valuable information in central nervous system disorders.
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