title: Interhemispheric difference of pallidal local field potential activity in cervical dystonia.
abstract: BACKGROUND
  Cervical dystonia (CD) produces involuntary neck muscle contractions that result in abnormal and often asymmetrical postures of the head and neck. Basal ganglia oscillatory activity in the 3-12 Hz band correlating with involuntary muscle activity suggests a role in the pathophysiology of primary dystonia. Despite the asymmetrical postures seen with CD, no comparison of interhemispheric differences of pallidal local field potential (LFP) activity has been reported.
  
  
  OBJECTIVE
  The aim of this study was to examine the interhemispheric differences of LFP power in globus pallidus interna (GPi) in CD patients and compare these with their predominant head excursion identified as torticollis, laterocollis and retrocollis.
  
  
  METHODS
  LFPs were recorded from bilateral GPi in 11 patients with CD using microelectrodes during deep brain stimulation surgery. LFP power was measured in right and left GPi separately. The mean percentage of total GPi LFP power in 4-30 Hz frequency band on each brain side was determined and related to their predominant CD symptoms.
  
  
  RESULTS
  Interhemispheric difference in the mean percentage of LFP power in 4-12 Hz and 13-30 Hz band frequencies was found in patients with torticollis and laterocollis regardless of excursion direction. However, patients with retrocollis did not show interhemispheric difference in LFP activity in any band frequency.
  
  
  CONCLUSIONS
  Interhemispheric differences in synchronisation of pallidal LFP activity in 4-12 Hz and 13-30 Hz bands are related to the CD clinical condition, suggesting that these frequencies are important in the pathophysiology of dystonia.
authors.affiliation: Department of Clinical Neurosciences, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary, , Calgary, Alberta, Canada.
authors.forename: Jung Ryun
authors.initials: JR
authors.lastname: Lee
authors.forename: Zelma H T
authors.initials: ZH
authors.lastname: Kiss
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation; D004567:Electrodes, Implanted; D005260:Female; D007839:Functional Laterality; D005917:Globus Pallidus / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008839:Microelectrodes; D008875:Middle Aged; D013238:Stereotaxic Techniques; D014103:Torticollis / Q000503:physiopathology*
keywords: DYSTONIA; ELECTRICAL STIMULATION; MOVEMENT DISORDERS; NEUROPHYSIOL, CLINICAL