The standing body sway of normal subjects and of patients with unilateral vestibular disorders was measured. The patients were not able to stand with toes and heels together, so the upright position with toes and heels apart was applied. Visual stimulation consisted of clockwise and counter-clockwise concentrically-moving spotlights at constant velocities of 60 and 90 deg/sec. The body sway of the patients was significantly larger during contralateral stimulation by moving spotlights than during ipsilateral moving stimulation, while the sway of normal subjects was symmetrical, increasing with increasing velocity.
