title: Can Postural Instability Respond to Galvanic Vestibular Stimulation in Patients with Parkinson's Disease?
abstract: OBJECTIVE
  Galvanic vestibular stimulation (GVS) activates the vestibular afferents, and these changes in vestibular input exert a strong influence on the subject's posture or standing balance. In patients with Parkinson's disease (PD), vestibular dysfunction might contribute to postural instability and gait disorders.
  
  
  METHODS
  Current intensity was increased to 0.7 mA, and the current was applied to the patients for 20 minutes. To perform a sham stimulation, the current intensity was increased as described and then decreased to 0 mA over the course of 10 seconds. The patient's status was recorded continuously for 20 minutes with the patient in the supine position.
  
  
  RESULTS
  Three out of 5 patients diagnosed with PD with postural instability and/or abnormal axial posture showed a reduction in postural instability after GVS. The score for item 12 of the revised Unified Parkinson's Disease Rating Scale part 3 was decreased in these patients.
  
  
  CONCLUSIONS
  The mechanism of postural instability is complex and not completely understood. In 2 out of the 5 patients, postural instability was not changed in response to GVS. Nonetheless, the GVS-induced change in postural instability for 3 patients in our study suggests that GVS might be a therapeutic option for postural instability.
authors.affiliation: Department of Neurology, Nara Medical University, Nara, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kataoka
authors.affiliation: Graduate School of Health Science, Kio University, Nara, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Okada
authors.affiliation: Department of Neurology, Nara Medical University, Nara, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Kiriyama
authors.affiliation: Graduate School of Health Science, Kio University, Nara, Japan.
authors.forename: Yorihiro
authors.initials: Y
authors.lastname: Kita
authors.affiliation: Graduate School of Health Science, Kio University, Nara, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Nakamura
authors.affiliation: Graduate School of Health Science, Kio University, Nara, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Morioka
authors.affiliation: Graduate School of Health Science, Kio University, Nara, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Shomoto
authors.affiliation: Department of Neurology, Nara Medical University, Nara, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ueno
keywords: Galvanic vestibular stimulation; Parkinson; Postural instability; Posture.; Vestibular dysfunction; Vestibular stimulation