Influence of low dose alcohol on fixation suppression.

The decrease of fixation suppression after small doses of alcohol was studied in 40 healthy volunteers (20 male, 20 female) using rotatory stimulation. 0.5 g alcohol per kg body weight were given within 20 min. The maximum fixation suppression and blood alcohol concentrations (BAC) were measured before and at 15, 30, 45, 60, 120, 180 and 240 min after ingestion. We determined the maximum angular acceleration during which total suppression of the vestibulo-ocular-reflex (VOR) was still possible. Fixation suppression was successful up to mean values of 43.6 degrees/S2 before ingestion of alcohol (reference level). A first significant deterioration of fixation suppression was observed at BAC of 20 mg/100 ml decreasing constantly with increasing BAC. At the median maximum BAC of 65 mg/100 ml, fixation suppression was possible up to acceleration values of 20% compared with reference levels. Measuring of the maximum fixation suppression in rotational tests is a reproducible easy method to describe the central nervous system control of vestibular functions. This method shows impressingly the enormous effects of low doses of alcohol on equilibrium. It is concluded that at BAC of more than 50 mg/100 ml a remaining vestibular nystagmus might be observed when driving a bend.