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Sinusoidal rotatory test was performed to evaluate the vestibular function in 27 adults with 19∼25 years old(22±1.6, mean±SD). Vestibuloocular reflex induced by sinusoidal rotation of the whole body was analyzed in terms of gain, phase difference and directional preponderance. Sinusoidal rotatory chair controlled by DC servo-motor was manufactured : the range of rotation was 0∼±720˚ . and the range of frequency was 0.01∼0.4㎐. Nystagmus was occurred by sinusoidal rotation, and the direction of nystagmus was corresponded to the direction of rotation, also the velocity of nystagmus was proportioned to the velocity of rotation. In vestibuloocular reflex induced by sinusoidal rotation, gain was 0.60±0.02 at stimulus frequency of 0.05 ㎐, 0.63±0.02 at 0.1 ㎐, 0.58±0.02 at 0.2 ㎐, and phase was 28.4±0.8˚ at 0.05 ㎐, 18.7±0.8˚ at 0.1 ㎐, 11.5±0.6˚ at 0.2 ㎐, also directional preponderance was 5.3±1.0% at 0.05 ㎐, 2.9±0.5% at 0.1 ㎐, 2.9±0.3% at 0.2 ㎐. Gain, phase and directional preponderance in the vestibuloocular reflex induced by sinusoidal rotation must be measured in order to evaluate the vestibular function. And the sinusoidal rotatory chair manufactured in this study could be useful clinically to evaluate the vestibular function in patients with vestibular disorders.
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