title: Patterns of Cortical Synchronization in Isolated Dystonia Compared With Parkinson Disease.
abstract: OBJECTIVE
  Isolated dystonia and Parkinson disease (PD) are disorders of the basal gangliothalamocortical network. They have largely distinct clinical profiles, but both disorders respond to deep brain stimulation (DBS) in the same subcortical targets using similar stimulation paradigms, suggesting pathophysiologic overlap. We hypothesized that, similar to PD, isolated dystonia is associated with elevated cortical neuronal synchronization.
  
  
  OBJECTIVE
  To investigate the electrophysiologic characteristics of the sensorimotor cortex arm-related area using a temporary subdural electrode strip in patients with isolated dystonia and PD undergoing DBS implantation in the awake state.
  
  
  METHODS
  An observational study recruited patients scheduled for DBS at the University of California, San Francisco and the San Francisco Veterans Affairs Medical Center. Data were collected from May 1, 2008, through April 1, 2015. Findings are reported for 22 patients with isolated cervical or segmental dystonia (8 with [DYST-ARM] and 14 without [DYST] arm symptoms) and 14 patients with akinetic rigid PD. Data were analyzed from November 1, 2014, through May 1, 2015.
  
  
  METHODS
  Cortical local field potentials, power spectral density, and phase-amplitude coupling (PAC).
  
  
  RESULTS
  Among our 3 groups that together included 36 patients, cortical PAC was present in primary motor and premotor arm-related areas for all groups, but the DYST group was less likely to exhibit increased PAC (P = .008). Similar to what has been shown for patients with PD, subthalamic DBS reversibly decreased PAC in a subset of patients with dystonia who were studied before and during intraoperative test stimulation (n = 4). At rest, broadband gamma (50-200 Hz) power in the primary motor cortex was greater in the DYST-ARM and PD groups compared with the DYST group, whereas alpha (8-13 Hz) and beta (13-30 Hz) power was comparable in all 3 groups. During movement, the DYST-ARM group had impaired beta and low gamma desynchronization in the primary motor cortex.
  
  
  CONCLUSIONS
  Isolated dystonia and PD have physiologic overlap with respect to high levels of motor cortex synchronization and reduction of cortical synchronization by subthalamic DBS, providing an explanation for their similar therapeutic response to basal ganglia stimulation.
authors.affiliation: Movement Disorder and Neuromodulation Center, Department of Neurology, University of California, San Francisco.
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Miocinovic
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Coralie
authors.initials: C
authors.lastname: de Hemptinne
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Salman
authors.initials: S
authors.lastname: Qasim
authors.affiliation: Movement Disorder and Neuromodulation Center, Department of Neurology, University of California, San Francisco.
authors.forename: Jill L
authors.initials: JL
authors.lastname: Ostrem
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Starr
mesh_terms: D000328:Adult; D000368:Aged; D058256:Brain Waves / Q000502:physiology*; D003344:Cortical Synchronization / Q000502:physiology*; D046690:Deep Brain Stimulation / Q000379:methods; D020821:Dystonic Disorders / Q000503:physiopathology* / Q000628:therapy; D000069280:Electrocorticography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy; D055366:Synaptic Potentials / Q000502:physiology