title: Pallidal stimulation in cervical dystonia: clinical implications of acute changes in stimulation parameters.
abstract: OBJECTIVE
  Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is successful in dystonia, but the role of each electrical parameters of stimulation is unclear. We studied the clinical effects of acute changes of different parameters of GPi-DBS in cervical dystonia (CD).
  
  
  METHODS
  Eight CD patients with bilateral GPi-DBS at 28.6 +/- 19.2 (mean +/- SD) months after surgery were recruited. Mean improvement in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) severity score was 54.5% compared to before surgery. Ten settings, including a combination of a wide range of pulse widths (PWs), low and high frequencies and voltage, were administered in a randomized double blinded fashion. Clinical benefit was assessed by two raters using the TWSTRS and by the patients using an analogue rating scale.
  
  
  RESULTS
  The TWSTRS severity scores were reduced by 56.7% with stimulation at the best settings. Improvement was significantly associated with high frequency (> or = 60 Hz) and high voltage. Stimulation at 130 Hz showed the best clinical improvement. Increasing PWs (from 60 to 450 micros) did not result in a significant improvement.
  
  
  CONCLUSIONS
  Frequency and amplitude appear to be the most important factors in the acute anti-dystonic effects in GPi-DBS patients with CD.
authors.affiliation: Movement Disorders Center, Toronto Western Hospital, University of Toronto, University Health Network, Toronto, ON, Canada. elena.moro@uhn.on.ca
authors.forename: E
authors.initials: E
authors.lastname: Moro
authors.forename: P
authors.initials: P
authors.lastname: Piboolnurak
authors.forename: T
authors.initials: T
authors.lastname: Arenovich
authors.forename: S W
authors.initials: SW
authors.lastname: Hung
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Poon
authors.forename: A M
authors.initials: AM
authors.lastname: Lozano
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D046690:Deep Brain Stimulation / Q000379:methods*; D004311:Double-Blind Method; D005260:Female; D005917:Globus Pallidus / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014103:Torticollis / Q000503:physiopathology / Q000628:therapy*