Effect of Peripheral Vestibular Disorders on Head-Trunk Coordination during Postural Sway in Humans

The experiments in this study were performed to analyze how head motion is controlled during postural sway in two groups of patients with vestibular disorders and in normal subjects. The subjects were tested in conditions that resulted in postural sway primarily about the ankles, with little motion of the trunk, and in conditions that led to large motions of the body about the hips, with substantial motion of the trunk. The results have shown that the head and trunk movements are uncoordinated in normal subjects and patients with severe bilateral deficits. The results also indicated that when postural sway results in large movements of the trunk, the head movements of the normal subjects are controlled in a way that provides a stable platform for the vestibular and visual systems.