No Effects of Acute Alcohol Ingestion on Subjective Visual Horizontal Determination During Eccentric Rotation

Evaluating the function of the vestibular part of the inner ear comprises more than the classic analysis of the lateral semicircular canal function. In healthy subjects, positional alcohol nystagmus may be seen after acute alcohol ingestion. Posturography has shown a deteriorated equilibrium after even moderate doses of alcohol, which speculatively could be an effect of otolith disturbance or a central integrative effect. We tested the possibility of an otolith effect by using linear acceleration in the lateral direction by means of eccentric rotation, stimulating mainly the outermost ear's otolith organ. The subject is seated eccentrically in a rotatory chair facing the direction of rotation. Thus, the otolith organs are stimulated in steady-state rotation. The subject experiences a lateral tilt and, in darkness, is instructed to put a short light bar in the position thought to be that of a water surface, which is identical to the perceived tilt. Twenty healthy subjects (10 men, 10 women) aged 20-29 years were tested before and approximately 1 hour after ingestion of alcohol, the amounts consumed corresponding to an approximate blood alcohol level of 0.05%, well above the maximum permissible level for driving in Sweden. No significant effects of alcohol were found. The otolith function probably is not affected by moderate alcohol intoxication levels. From this point of view, equilibrium deterioration due to alcohol ingestion in the erect position is caused by a central integrative deficit and not by an otolith effect.