Galvanic stimulation produces postural sway and eye movements in human
s, Since galvanic currents are thought to exert their effect at the tr
igger zone of the vestibular nerve, an intact vestibular nerve should
be necessary to produce a response, We have used galvanic stimulation
in humans to test the hypothesis that intact vestibular nerve fibers a
re required to obtain a postural sway response, Experimental subjects
included normal subjects, patients who had undergone resection of an a
coustic neuroma, and patients who bad undergone vestibular neurectomy
and surgical labyrinthectomy, Our results support the hypothesis that
an intact vestibular nerve is necessary to produce a response. Moreove
r, two patients with recurrent vertigo following vestibular neurectomy
and labyrinthectomy, who had absent ice-water caloric test responses
in the operated ears, were found to have a positive galvanic response.
This result suggested that their recurrent vertigo was based on intac
t residual vestibular nerve fibers, Although previous research has not
yielded a routine clinical use for galvanic stimulation, our results
suggest that galvanic stimulation of the vestibular system can provide
unique and valuable diagnostic information.