title: Use of surface electromyography to assess and select patients with idiopathic dystonia for bilateral pallidal stimulation.
abstract: OBJECTIVE
  The object of this study was to identify a preoperative physiological index by using surface electromyography (EMG) signals that would correlate with clinical outcome in dystonic patients following bilateral pallidal stimulation.
  
  
  METHODS
  In 14 patients with spasmodic torticollis, generalized dystonia, and myoclonic dystonia, surface EMG signals were recorded from the most affected muscle groups. Although the dystonia affected different body segments, the EMG signals in all patients could be decomposed into bursting and sustained components. Subsequently, a ratio of the EMG amplitude was calculated between the two components and then correlated with clinical outcome. Patients who experienced rapid improvement following bilateral pallidal stimulation had a significantly higher EMG ratio compared with those who did not. Furthermore, a significant correlation was found between the EMG ratio and clinical improvement during the 12-month period following pallidal stimulation.
  
  
  CONCLUSIONS
  The authors concluded that surface EMG studies could be used to predict the clinical outcome of and to select patients for pallidal stimulation for dystonia.
authors.affiliation: University Laboratory of Physiology, University of Oxford, United Kingdom.
authors.forename: Shouyan
authors.initials: S
authors.lastname: Wang
authors.forename: Xuguang
authors.initials: X
authors.lastname: Liu
authors.forename: John
authors.initials: J
authors.lastname: Yianni
authors.forename: Alex L
authors.initials: AL
authors.lastname: Green
authors.forename: Carole
authors.initials: C
authors.lastname: Joint
authors.forename: John F
authors.initials: JF
authors.lastname: Stein
authors.forename: Peter G
authors.initials: PG
authors.lastname: Bain
authors.forename: Ralph
authors.initials: R
authors.lastname: Gregory
authors.forename: Tipu Z
authors.initials: TZ
authors.lastname: Aziz
mesh_terms: D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation; D004421:Dystonia / Q000503:physiopathology* / Q000628:therapy*; D004576:Electromyography; D005500:Follow-Up Studies; D005917:Globus Pallidus; D006801:Humans; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D018579:Patient Selection; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016896:Treatment Outcome