Response to galvanic vestibular stimulation in patients with unilateral vestibular loss.
OBJECTIVE
This study sought to characterize various responses to galvanic vestibular stimulation (GVS) by comparing GVS-induced eye movements in healthy subjects and patients with vestibular function loss. The study also aimed to estimate the clinical significance of GVS tests. Finally, an effort was made to localize the primary excitation site of stimulation in the vestibular system.


METHODS
Three parameters of response to GVS, spontaneous nystagmus, galvanic stimulating nystagmus (GSN), and postgalvanic stimulating nystagmus (PGSN), were evaluated in 20 normal subjects and 14 patients with complete unilateral vestibular function loss resulting from labyrinthectomy or vestibular neurectomy using a three-dimensional video-electronystagmography technique.


RESULTS
In normal subjects, GSN was detected in all subjects and was directed toward the negative electrode. PGSN was also detected but was directed toward the opposite electrode. When the negative electrode was attached to the intact side in unilateral vestibular loss subjects, GSN was always directed toward the negative electrode and PGSN was never observed. When the negative electrode was attached to the lesion side, however, GSN was detected in only one case, and PGSN was observed and directed to the intact side in 13 patients.


CONCLUSIONS
The response to GVS in vestibular loss patients differed from that in normal subjects, which suggests that GVS could be useful for estimating the extent of vestibular function loss. The fact that the patterns of GVS response differed so significantly suggests that the primary site of excitation is not central but is instead the peripheral vestibular organ.
Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea.
Hyun Jik
HJ
Kim
Jae Young
JY
Choi
Eun Jin
EJ
Son
Won-Sang
WS
Lee
D000293:Adolescent; D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D004584:Electronystagmography; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000175:diagnosis / Q000628:therapy; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000503:physiopathology; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D015837:Vestibular Diseases / Q000175:diagnosis* / Q000628:therapy; D014724:Vestibular Function Tests