Analysis of Postural Change during Caloric Stimulation in Man (2)

Abstract

To clarify the influence of the vestibular stimulation upon the upright standing, we tried to analyse the postural change by the caloric stimulation with warm and cold water systematically.
The subjects were 8 healthy males. They were asked to stand on the platform with their eyes closed. In 4 subjects unilateral (right side) caloric stimulation was performed and in another 4 subjects simultaneous bilateral caloric stimulation was performed. The postural change was analysed using the output of the X axis component (left-right direction of body sway) and Y axis component (anterior-posterior direction of body sway) from the platform. As special attention was paid to the postural deviation evoked by the caloric stimulation, we picked out a slow wave (less than 0.15 Hz) from the X and Y axis components by the digital filter with the aid of a microcomputer.
In the linear stabilometry, left and anterior postural deviation occurred by the caloric stimulation to the right side with warm water. Right and anterior postural deviation occurred by the caloric stimulation to the right side with cold water. Simultaneous bilateral caloric stimulation evoked only anterior or posterior postural deviation. The posterior deviation was evoked by warm water and anterior deviation was evoked by cold water. In the spot stabilometry, left-right and anterior-, posterior body sway was occurred by the unilateral caloric stimulation and anteriorposterior body sway was occurred by the bilateral caloric stimulation.
We considered that this study would be a model of the vertigo evoked by unilateral or bilateral inner ear disorders and further investigation of this study would lead us to clarify the role of the vestibular function during upright standing.