Postural disturbance in patients with benign paroxysmal positional nystagmus.

Abnormal vestibular function disrupts postural and ocular muscle control system references to gravity (earth) vertical. Vestibular disorders also prevent satisfactory resolution of normally redundant, but often conflicting, visual and somatosensory spatial references required for normal postural control during active and passive body motion. Using a moving platform and visual surrounds posturography technique to systematically interact visual, somatosensory, and vestibular inputs, it was clearly demonstrated that patients with the benign paroxysmal positional nystagmus type of distorted vestibular function employ an unstable, visually dependent postural sway distinct from the postural instability associated with unilateral or bilateral vestibular functional deficits. These findings have important clinical implications for diagnosis and management of patients with vestibular disorders.