title: Multichannel Electromyographic Mapping to Optimize OnabotulinumtoxinA Efficacy in Cervical Dystonia.
abstract: BACKGROUND
  Cervical dystonia (CD) is characterized by sustained, involuntary contraction of head and neck muscles. Botulinum toxin injections are established as safe and effective, but unfortunately 15-25% of patients fail to respond. The aim of this study was to examine whether multichannel electromyogaphic mapping improved outcomes in a cohort of antibody-negative onabotulinumtoxinA non-responders by more precisely identifying which muscles were involved in the dystonia.
  
  
  METHODS
  Patients with cervical dystonia who had "failed chemodenervation therapy" administered by an outside provider were enrolled in a single-blind, randomized, crossover design study. Patients received either a multichannel electromyographic mapping study prior to the first botulinum toxin injection, which was followed by use of only a single-lead injection 16 weeks later (injected by an alternate and blinded movement disorders specialist) or vice versa. The primary outcome measure was change in total Toronto Western Spasmodic Torticollis Rating Scale score 4 weeks after each injection compared with each pre-injection baseline score.
  
  
  RESULTS
  Nine subjects completed this study. Mean percentage improvement in Total Toronto Western Spasmodic Torticollis Rating Scale was 23.5% using multichannel electromyography compared with 9% using the single-channel technique (p = 0.11).
  
  
  CONCLUSIONS
  This pilot study suggests that multichannel electromyographic mapping may result in improved efficacy in the treatment of antibody-negative onabotulinumtoxinA refractory CD.
authors: Department of Neurology, University of California, San Francisco, San Francisco, California, United States of America ; Parkinson's Disease Research, Education, and Clinical Center, San Francisco Veterans Affairs Medical Center, San Francisco, United States of America.
authors: Camilla
authors: C
authors: Kilbane
authors: Jill
authors: J
authors: Ostrem
authors: Nicholas
authors: N
authors: Galifianakis
authors: Jamie
authors: J
authors: Grace
authors: Leslie
authors: L
authors: Markun
authors: Graham A
authors: GA
authors: Glass
keywords: Cervical dystonia; botulinum toxin; botulinum toxin non-responders; electromyography; torticollis