A New Apparatus for Examination of the Vestibulo-ocular System

Abstract

A new apparatus capable of recording head and eye movements was devised to examine the vestibulo-ocular system. Horizontal and vertical head movements were recorded with a sensor of terrestrial mgnetism. Eye movenments were recorded by an electronystagmographic technique. The transmitted data were stored on a floppy disc and analyzed with a microcomputer in a specially designed program. 1. The apparatus was useful as a tool for recording spontaneous and gaze nystagmus and pursuit and saccadic eye movements in patients with labyrinthine and central disturbances. 2. Transfer function (gain and phase) of the vestibulo-ocular system was calculated with head and eye movements obtained from pseudo-random head oscillation in the dark. In normal subjects, gain with head movements as input signal and eye movements as output signal indicated a frequency-dependent gain enhancement; the phase difference between head eye movements was 180°. 3. The vestibulo-ocular reflex (VOR) induced by the right and left labyrinth were examined with velocity recording of head and eye movements induced by quick head movements to the right and left at intervals of 1 second in the dark. Patients with unilaterl labyrinthine disturbance showed a low amplitude response in head movements toward the affected labyrinth. 4. The integration mechanism in the pursuit system was examined from the velocity recording of eye movements during vertical head oscillation with fixation on a visual target. A patient with primary position upbeat nystagmus caused by nutritional deficiency encephalopathy showed a disturbance of the up neural integrator from velocity signal to position signal in the visual vestibular oculomotor system. The apparatus was usuful for the examination of the vestibulo-ocular system of patients with vertigo and equilibrium disturbances. © 1993, Japan Society for Equilibrium Research. All rights reserved.