Use of a computerized postural sway measurement system for neurobehavioral toxicology.

The study of standing posture has been associated with nervous system functioning for over a hundred years. Measures of human standing ability have attracted some attention as indicators of neurotoxic insult. The use of postural sway measures as subclinical indicators of toxicity has not been regularly incorporated into most neurobehavioral test batteries, but the development of microcomputer-controlled systems offers new possibilities. The mechanisms involved in controlling postural sway are discussed, as well as the various measurement techniques. In addition, studies involving the effects of some neurotoxic agents are cited. A postural sway measurement system that is noninvasive, has 1-2-minute test periods, provides immediate test results, and is relatively free of practice and motivation effects is described. Results present the normative characteristics of the sway parameters, a comparison of three data transformation techniques, and the effects of height and weight on the sway parameters. Power calculations were also performed to estimate the number of subjects needed to detect effects at both the 80% and 90% power levels.