BACKGROUND: The aim of our study was to estimate the qualitative and quantitative influence of different blood alcohol concentrations on the results of vestibular testing. METHODS: We investigated the influence of ethanol on the results of well established neurootologic tests in 40 persons with blood alcohol concentrations of 0.0%, 0.4%, and 0.8%. RESULTS: The intensity of the vestibuloocular reflex during sinusoidal rotation was not influenced by ethanol. The directional preponderance of the nystagmic responses to the left was enlarged from 5.8% (0.0/1000) to 13.4% (0.4/1000) and to 15.5% (0.8/1000). The capability of suppressing the vestibuloocular reflex by visual fixation was reduced to 70% (0.4/1000) and, respectively, 46% (0.8/1000) of the 0.0/1000 result. The maximum speed of smooth pursuit was diminished to 84.1% (0.4/1000) and, respectively, 65.3% (0.8/1000) of the 0.0/1000 values. The pursuit movements resembled those of patients with central vestibular lesions. The latency of saccades increased from 200 ms (0.0/1000) to 220 ms (0.4 and 0.8/1000); the velocity was not changed by ethanol. At maximum target speed the gain of optokinetic nystagmus was reduced at 0.4/1000 to 66.3% and at 0.8/1000 to 51.7%, with different results to the right and the left side. CONCLUSIONS: Our results show that even slight amounts of ethanol can simulate symptoms of vestibular diseases, resulting in false diagnoses and errors in determining the therapeutic strategy.
