Body sway in normal subjects was analyzed by means of various methods to study a role of cervical muscles in galvanic body sway test. Galvanic stimulation through the retro-auricular electrode induced an initial response and a deviation response in body sway.
When the anodal stimulation was given through the right retro-auricle during standing, a deviation response toward the right side was obseved. While keeping a posture weighted on one foot, the stimulation induced a similar response. The stimulation during squatting produced also a deviation response toward the right side. When the head was rotated to the right, the stimulation produced backward responses. When rotated to the left, it produced forward responses. Even without galvanic stimulation, similar responses were also induced by some other method, for example, inclining the head to one side. Galvanic stimulation while sitting resulted in slight but apparent head inclination.
The results suggested that cervical muscles played an important role in galvanic body sway test. Initial and deviation responses appeared to be secondarily produced by changes in the cervical muscular tension.