[Impaired vestibular diagnosis by the effect of alcohol]

The aim of our study was to estimate the qualitative and quantitative influence of different blood alcohol concentrations on the results of vestibular testing.

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%.

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.

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.