Postural stability following mild head or whiplash injuries

Studies of the sequelae of head injury suggest that cochlear and vestibular dysfunctions, comprise some of the most frequently reported delayed complications following head trauma. To date, little attention has been given to the relation between post-traumatic subjective symptoms of dizziness and the objective measures of postural stability or balance. The purpose of this study was to quantify the balance deficits in individuals who had developed symptoms of dizziness following mild head and whiplash injuries. The balance abilities of 29 patients, who developed dizziness following some type of mild head or whiplash injury, were compared to those of 51 healthy symptom-free subjects. Balance was assessed by examining the center-of-pressure movements, in the anterior-posterior and medial-lateral directions, and the total movement displacement. The isolated contributions of visual and somatosensory inputs were estimated by comparing the magnitudes of the center-of-pressure movements for the various sensory conditions. Data were collected from three 30-second trials of each combination of three visual conditions (accurate, absent, and inaccurate) and two somatosensory conditions (accurate and inaccurate), with the patient standing on a fixed-force platform. Univariate analyses of variance indicated that the group with head injury, compared to the control group, exhibited significantly greater anterior-posterior movements in four of the six sensory conditions and greater total movement displacement during the inaccurate vision/inaccurate somatosensation condition. These data suggest that patients who have sustained head or neck trauma exhibit increased reliance on accurate visual input and are unable to utilize vestibular orienting information to resolve conflicting information from the visual and somatosensory systems.