Vestibulo-ocular reflex abnormality in Behçet's disease.

Visual modulation of the vestibulo-ocular reflex (VOR) was analyzed in 16 patients with non-neurologic Behçet's disease who had no manifest vestibular or ocular-motor symptoms. The VOR gains in the darkness were elevated in 63% of the patients. The elevated gain in the darkness was not attributed with certainty to vestibular adaptation to defective smooth pursuit, because only 25% of the patients manifested impaired smooth pursuit eye movements. Visual impairment occurred in some patients but did not correlate with the VOR elevation. An unknown mechanism affecting the vestibular system has been considered. The VOR elevation in the darkness may suggest the presence of a latent brainstem abnormality in the patients.