title: Botulinum toxin type A and EMG: a key to the understanding of chronic tension-type headaches?
abstract: BACKGROUND
  The pathogenesis of chronic tension-type headache remains unclear, and the role of muscle tension is especially controversial. Botulinum toxin type A, a potent inhibitor of muscle tone, has been used to treat chronic tension-type headache.
  
  
  OBJECTIVE
  To determine whether clinical response to treatment of chronic tension-type headache with Botox A parallels changes in resting muscle activity recorded through serial electromyography (EMG).
  
  
  METHODS
  We randomly assigned eight patients with chronic tension-type headache to pericranial injection of 500 MU Botox A versus placebo (isotonic saline).
  
  
  RESULTS
  At 6 and 12 weeks following treatment, there were no significant differences in clinical outcome between the placebo and the Botox A groups. This occurred despite EMG evidence of a reduction in resting muscle activity in the Botox A-treated patients.
  
  
  CONCLUSIONS
  These results support the hypothesis that peripheral mechanisms such as increased muscle tone play, at most, a minor role in the pathophysiology of chronic tension-type headache.
authors.affiliation: Department of Neurology, Medical School of Hannover, Germany.
authors.forename: J D
authors.initials: JD
authors.lastname: Rollnik
authors.forename: M
authors.initials: M
authors.lastname: Karst
authors.forename: M
authors.initials: M
authors.lastname: Fink
authors.forename: R
authors.initials: R
authors.lastname: Dengler
mesh_terms: D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000494:pharmacology / Q000627:therapeutic use*; D002908:Chronic Disease; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000503:physiopathology*; D009465:Neuromuscular Agents / Q000494:pharmacology / Q000627:therapeutic use*; D010865:Pilot Projects; D018781:Tension-Type Headache / Q000188:drug therapy* / Q000503:physiopathology*
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A