Effects of alcohol ingestion on vestibular function in postural control.

In order to define the acute effects of a moderate quantity of alcohol on balance, related to the vestibular function, vestibulo-ocular reflex (VOR) test, caloric test and dynamic posturography (EquiTest) were performed. Ten healthy male volunteers aged 19-27 average 22.8) years old imbibed 1.5 ml whisky (alcohol content 43%) per kilogram of body weight within 5 min. Blood alcohol level (BAL) was measured before administration and then after 30, 90, and 150 min. Equilibrium examinations were performed immediately after each blood sample was taken. At the highest alcohol level, significant reductions were found in VOR gain, in the maximum slow-phase velocity of the caloric test and in the equilibrium score of the sensory organization test in condition 5, when compared with those before drinking. In some typical cases, the subjects' response in all tests were most disturbed at the time when the highest alcohol level was measured. From our results, we conclude that a moderate quantity of alcohol affects not only the oculomotor system but also the vestibular system. Furthermore, it was suggested that one of the reasons for postural instability after drinking alcohol may be reduced vestibular function.