Quantitative analysis of the visual vestibulo-ocular reflex using sinusoidal rotation in patients with peripheral vestibular disorders.

In order to investigate interaction of the vestibular and optokinetic systems in patients with peripheral vestibular disorders, the visual vestibulo-ocular reflex (V-VOR) gain in 49 patients with peripheral vestibular disorders was quantitatively measured by using pendular harmonic sinusoidal rotation with optokinetic stationary stimuli. The patients were rotated sinusoidally both with eyes closed and open at an amplitude of 240 degrees and at a frequency of 0.1 Hz (peak velocity 75.4%s). Comparing the vestibulo-ocular reflex (VOR) and V-VOR gains in the patients with definite Meniere's disease (23 cases), benign paroxysmal positional vertigo (BPPV, 13 cases) and sudden deafness with vertigo or dizziness (13 cases), the VOR-DP and normal V-VOR gain were more frequently observed in patients with Meniere's disease (13 cases) and sudden deafness (7 cases) than in those with the BPPV (3 cases). In the four patients with bilateral Meniere's disease and sudden deafness, abnormally decreased VOR-gain (under 0.55) in the bilateral directions with slightly decreased V-VOR gain was measured when tested independently. However, abnormal V-VOR gain was observed in only one case of sudden deafness due to retrocochlear lesions. From our VOR and V-VOR gain observations comparing the caloric responses, we have concluded that the comparison of VOR with V-VOR gains provides additional information for evaluation of peripheral vestibular disorders as well as central nervous system disorders.