Heterogeneity of effects of ethanol ingestion on postural stability as measured by two devices

Measurement of postural stability has been used to assess effects of exposure to selected neurotoxicants. Its widespread application has been limited by several factors, including the use of cumbersome, expensive measurement systems and limited demonstration of sensitivity for detecting neurotoxicity. Recently, a less expensive, portable device for assessing postural stability via measurement of head position has been developed and used in some field studies. Although this head position monitor (HPM) is commercially available, no validation information for it has been published. To evaluate the HPM's utility, it was compared to a force platform (FP) system in an ethanol experiment. Ten adult male subjects were given 0.5 ml/kg ethanol and placebo using a counterbalanced, cross-over design. Stability measurements were made immediately prior to administration of alcohol or placebo and at fifteen minute intervals for two hours following administration. At each time interval, stability was monitored during two eyes-open trials alternated with two eyes-closed trials, each of 60-second duration. On a group basis, marginally significant effects of alcohol consumption consistent with results of other published studies were observed with both devices. The maximum increase in speed of sway occurred at 15 minutes post-ethanol ingestion for the eyes-closed condition. Specifically, sway speed increased from 1.11 cm/sec pre-ingestion to 1.50 cm/sec 15 minutes post-ingestion for the HPM, and from 1.81 m/sec to 2.13 cm/sec for the FP. No significant increase in sway speed was observed for the eyes-open condition. These groups differences obscured substantial heterogeneity of response to ethanol among the ten subjects, i.e., only two of the 10 subjects showed an observable increase in sway speed following ethanol ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)