title: Galvanic-induced body sway in vestibular schwannoma patients: evidence for stimulation of the central vestibular system.
abstract: OBJECTIVE
  To investigate the various possible sites of excitation by galvanic stimulation by comparing the galvanic-induced body sway (GBS) in vestibular schwannoma (VS) patients with that in healthy subjects.
  
  
  METHODS
  This was a prospective experimental study conducted in a tertiary referral centre. In a previous study we developed a standardized procedure for reproducible quantification of GBS using a monaural continuous 1-cosinusoidal stimulus (0.5 Hz; 2 mA). In this study, 23 VS patients were tested before and 12 VS patients were also tested after surgical intervention (extirpation of tumour with concomitant vestibular neurectomy) and the results were compared with those obtained in 47 healthy subjects.
  
  
  RESULTS
  There were no significant differences in mean total GBS gain between VS patients and healthy subjects (p>0.05) before surgical intervention. After vestibular neurectomy a significant difference in the mean total GBS gain was observed, but GBS was still present after surgery.
  
  
  CONCLUSIONS
  These results prove that galvanic vestibular stimulation excites the central vestibular system even when conduction via the vestibular nerve is hampered.
authors.affiliation: Department of Otorhinolaryngology--Head and Neck Surgery, University Hospital Maastricht, The Netherlands. s.balthe@jbz.nl
authors.forename: Susan G T
authors.initials: SG
authors.lastname: Balter
authors.forename: Martijn H
authors.initials: MH
authors.lastname: Castelijns
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Stokroos
authors.forename: Herman
authors.initials: H
authors.lastname: Kingma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D005712:Galvanic Skin Response; D034381:Hearing Loss / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000503:physiopathology* / Q000601:surgery; D011446:Prospective Studies; D014725:Vestibular Nerve / Q000503:physiopathology* / Q000601:surgery; D014722:Vestibule, Labyrinth / Q000503:physiopathology / Q000601:surgery; D000160:Vestibulocochlear Nerve Diseases / Q000503:physiopathology* / Q000601:surgery