Readers would either have had a personal experience or observed the inelegant gait of the inebriated. Re-aligning the body during postural perturbations involves changes in head position, shoulders, and hip, knee and ankle joints. The main hypothesis of this study was that alcohol intoxication would cause misalignment of the head and other body segments in upright stance. A secondary aim was to investigate whether alcohol intoxication affects the ability for the body to adapt and maintain accurate body alignment during balance perturbations. Twenty-five adult subjects with no neurological / neuro-otological disease were recruited. The subjects consumed an unspecified amount of 70% ethanol diluted in elderflower juice. The balance tests required subjects to stand on a platform in quiet stance without perturbations and in upright posture with perturbations using calf muscle vibration, with eyes open and eyes closed. To measure the changes in posture in the antero-posterior and lateral directions, sensors were attached to five areas: head, shoulder, hip, knee and ankle. The tests were performed once a week for three weeks at three blood alcohol levels (BAC): 0.00%, 0.06% and 0.10%. In the absence of alcohol intoxication (BAC 0.00%), head position was more anterior when the eyes were closed. This head position increased further when perturbations were introduced; the position of the knee in quiet stance became more posterior, that is rigid, at higher BAC, made worse by both perturbations and eye closure. There was a significantly greater lateral displacement of the head, and antero-posterior displacement of the shoulders at high BACs. The displacements were worse during perturbations. An interesting finding was that the rigid alignment of the body when intoxicated was worse when the eyes were open than when closed, indicating that visual stabilisation is inadequate in compensating for alcohol-induced ataxia. Vertical alignment of the head was affected by alcohol intoxication most likely due to impairment in the perception of true vertical. The authors conclude that the changes in body alignment and the poor compensatory mechanisms probably contribute to the risk of falling in the inebriated.
