title: The galvanic whole-body sway response in health and disease.
abstract: OBJECTIVE
  To explore the galvanic-evoked vestibulospinal reflex in health and disease.
  
  
  METHODS
  Vestibular-evoked whole-body movement was measured in 60 controls and eight patients with bilateral vestibular impairment, using 1mA × 2s Galvanic Vestibular Stimulation (GVS). The displacement (s) and velocity (v) of 7 markers placed on the head, neck, shoulders, mid-thorax and hips and ground reaction forces (F) were recorded.
  
  
  RESULTS
  Monaural GVS evoked anterolateral whole-body movement away from the cathode. For controls, peak response magnitudes were 22.3 ± 12.4mm, 25.9 ± 14.3 mms(-1) and 3.2 ± 1.3N for s, v and F. Left right asymmetry measured using the Jongkee's formula was 12.59 ± 8.64%, 11.94 ± 11.09% and 11.68 ± 8.99% for s, v and F. All three measures were symmetrical for left and right mastoid stimulation and showed good to excellent test retest reliability. Patients with bilateral vestibular failure had absent or attenuated responses. For this patient group, the ("R/B") ratios between the "response period" and baseline body-sway for s, v and F were 2.1 ± 0.8, 1.7 ± 1.1 and 1.3 ± 0.6, which were significantly lower than 5.4 ± 4.2, 4.1 ± 2.5 and 2.3 ± 0.8 for controls, with s and v providing better separation between controls and patients. There were no significant correlations between the amplitudes of galvanic body sway responses and vestibular-evoked myogenic potentials (VEMPs).
  
  
  CONCLUSIONS
  GVS enables non-invasive assessment of the vestibulospinal reflex.
  
  
  CONCLUSIONS
  This method offers a clinically applicable, test of vestibular contributions to standing balance.
authors.affiliation: Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Central Clinical School, University of Sydney, Sydney, Australia.
authors.forename: Chantal M W
authors.initials: CM
authors.lastname: Tax
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Bom
authors.forename: Rachael L
authors.initials: RL
authors.lastname: Taylor
authors.forename: Nicholas
authors.initials: N
authors.lastname: Todd
authors.forename: Kuk-Ki J
authors.initials: KK
authors.lastname: Cho
authors.forename: Richard C
authors.initials: RC
authors.lastname: Fitzpatrick
authors.forename: Miriam S
authors.initials: MS
authors.lastname: Welgampola
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation; D005260:Female; D005712:Galvanic Skin Response; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D015203:Reproducibility of Results; D015837:Vestibular Diseases / Q000503:physiopathology*; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D014722:Vestibule, Labyrinth / Q000502:physiology; D055815:Young Adult
keywords: Galvanic; Sway; Vestibulospinal