Analysis of Deviation Reaction after Vestibular Stimulation

Abstract

In order to analyze the deviation reaction while standing using posturography, the author measured the deviation of the center of body sway and the velocity of body sway. Normal subjects after caloric vestibular stimulation and patients with equilibrium disturbance were examined. For the purpose of studying the influence of the vestibular system on leg extensor muscle tone, the H-reflex was investigated in normal subjects in the supine position after caloric vestibular stimulation.1) In normal subjects, when their eyes were closed, the center of body sway tended to shift to the front and the velocity of body sway to the back was faster than to the front.2) After unilateral caloric vestibular stimulation, normal subjects shifted to the stimulated side when cold air (24°C) was used and to the opposite side when warm air (50°C). was employed. The velocity was faster on the opposite side than the stimulated side with cold air and faster on the stimulated side with the warm air.3) In most of the patients with peripheral labyrinthine disorder who had nystagmus, the center of body sway shifted in the same direction as that of the slow phase of nystagmus and the velocity of body sway was high i n the direction of quick phase of nystagmus.4) After unilateral caloric vestibular stimulation, the frequency depression curve of the H-reflex showed the spastic type in both legs. With cold water (5°C), the contralateral leg was predominant, whereas with warm water (44°C), the ipsilatcral leg was predominant.