2021 Volume 80 Issue 2 Pages 57-62
A small maintained electrical current passed between electrodes on the skin over each mastoid (galvanic vestibular stimulation: GVS) activates the vestibular system and elicits vestibular responses, such as sensations of rotation, eye movements and postural instability. GVS has been used to test both human and animal vestibular systems. It modulates the vestibular signal by increasing the firing rate of afferents on the cathodal side and decreasing the firing rate on the anodal side, causing standing subjects to sway towards the anodal side. Although the neuronal pathways activated by GVS have been well delineated, the generated behavioral responses vary among individuals, depending critically on specific aspects of both the stimulation and recording conditions. Galvanic body sway test (GBST) provides important information for differential diagnosis between inner ear and retro-labyrinthine disorders of the vestibular system. On the other hand, interpretation of nystagmus was difficult, because precise measurement of eye movements by electronystagmography was not feasible. However, with the recent development of video-oculography (VOG), it has become possible to carry out accurate recording and evaluation of nystagmus. Recent technological developments, including the use of improved VOG, might lead to the rediscovery of GVS as a research and diagnostic tool.
