Ethanol-Induced Vestibular Dysfunction as a Model for Bilateral Vestibular Syndrome: Similarities in Video Head Impulse Test and Video-Oculography Data

BACKGROUND: The goal of this study was to compare video head impulse test, video-oculography, and clinical balance test changes induced by ethanol consumption, in order to acquire a model for acute bilateral vestibular syndrome. METHODS: Four healthy adult men and 5 healthy adult women were recruited as volunteers in the study. Initial video head impulse test, video-oculography, and clinical balance test examinations were made. Participants proceeded to drink standard alcohol doses until a maximum of 1.2‰ breath alcohol concentration was reached. Video head impulse test and clinical balance tests were repeated at every 0.2‰ breath alcohol concentration interval and at the final 1.0-1.2‰ breath alcohol concentration range. Video-oculography examinations were repeated at 1.0-1.2‰ breath alcohol concentration. RESULTS: Decrease in mean vestibulo-ocular gain at 60 ms between the 0‰ and 1.0-1.2‰ was 0.16 on the left side (P < .05) and 0.16 on the right side (P < .05). A borderline abnormality (mean 0.79/0.82) (left/right) was observed in vestibulo-ocular gain at the highest breath alcohol concentration. Corrective saccades increased significantly in amplitude and latency. There was a statistically significant, symmetrical decrease in video-oculography smooth pursuit gain. Saccade latency increased but statistically significantly only with right-sided cycles. Saccade accuracy remained constant. Optokinetic reflex gain showed significant decrease. Romberg’s test was performed with normal results initially and at 1.0-1-2‰ breath alcohol concentration. CONCLUSION: Ethanol produces a symmetrical loss in vestibulo-ocular gain measured by video head impulse test. Ethanol also decreases smooth eye pursuit gain and increases pro-saccade latency. Similar findings can be made in vestibular disorders as well as in cerebellar dysfunction. Central pathology should be ruled out in acute bilateral vestibular syndrome.