Effects of galvanic vestibular stimulation on the subjective visual vertical

초록

Background and Objectives : The aim of this study was to determine the otolithic effects of galvanic vestibular stimulation on the perception of subjective visual vertical in normal subjects. Materials and Method : Fifteen normal subjects were selected on the basis of medical history and neurological examination. We measured subjective tilt of a central vertical line during galvanic vestibular stimulation(0, 1.0, 2.5, 4.0 mA). Binaural and monaural electric current was applied to each subject's mastoid and forehead for vestibular stimulation. Results : Anodal stimulation of the right mastoid led to clock-wise subjective visual vertical. Anodal stimualtion of the left mastoid led to counter clock-wise subjective visual vertical. There was a correlation between the amount of the measured parameter and the strength of the applied current. More consistant parameters were obtained from the Binaural stimulation than the monaural stimualtion. Conclusion : Galvanic vestibular stimulation had effects on the vestibular functions, making changes in the subjective visual vertical. Since the galvanic stimulation had consistency with the direction of the stimulation and was proportionate to the intensity, it is thought to be a useful method for assessing otolith functions.