Man in motion. Historical and clinical aspects of vestibular function. A review.

This is a review of selected aspects of the history of the vestibular system (J. E. Purkyne, E. Mach, A. Crum-Brown) and of our current understanding of vestibular malfunction in clinical vertigo syndromes. Evidence is presented for a preliminary classification of central vestibular brainstem syndromes according to the three major planes of action of the vestibulo-ocular reflex (VOR): (1) disorders of the VOR in the horizontal (yaw) plane (horizontal nystagmus, pseudo 'vestibular neuritis'); (2) disorders of the VOR in the sagittal (pitch) plane (downbeat nystagmus; upbeat nystagmus); (3) disorders of the VOR in the frontal (roll) plane (ocular tilt reaction; lateropulsion). The pathophysiology of peripheral vestibular disorders is discussed: a specific gravity differential between the cupula fluid and the endolymph (buoyancy mechanism) causes vertigo in benign paroxysmal positioning vertigo and positional alcohol nystagmus. Vestibular neuritis is probably a partial unilateral vestibular paralysis due to viral infection of the superior division of the nerve trunk. The common post-traumatic vertigo is explained by otolith dysfunction secondary to dislodged otoconia resulting in unequal loads on the macula beds and a tonus imbalance between the two otoliths.