Efficacy and safety of botulinum type A toxin (Dysport) in cervical dystonia: results of the first US randomized, double-blind, placebo-controlled study

Mov Disord. 2005 Jul;20(7):783-91. doi: 10.1002/mds.20403.


Botulinum toxin type A (Dysport) has been shown in European studies to be a safe and effective treatment for cervical dystonia. This multicenter, double-blind, randomized, controlled trial assessed the safety and efficacy of Dysport in cervical dystonia patients in the United States. Eighty patients were randomly assigned to receive one treatment with Dysport (500 units) or placebo. Participants were followed up for 4 to 20 weeks, until they needed further treatment. They were assessed at baseline and weeks 2, 4, 8, 12, 16, and 20 after treatment. Dysport was significantly more efficacious than placebo at weeks 4, 8, and 12 as assessed by the Toronto Western Spasmodic Torticollis Rating Scale (10-point vs. 3.8-point reduction in total score, respectively, at week 4; P < or = 0.013). Of participants in the Dysport group, 38% showed positive treatment response, compared to 16% in the placebo group (95% confidence interval, 0.02-0.41). The median duration of response to Dysport was 18.5 weeks. Side effects were generally similar in the two treatment groups; only blurred vision and weakness occurred significantly more often with Dysport. No participants in the Dysport group converted from negative to positive antibodies after treatment. These results confirm previous reports that Dysport (500 units) is safe, effective, and well-tolerated in patients with cervical dystonia.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antibody Formation
  • Botulinum Toxins, Type A / therapeutic use*
  • Disability Evaluation
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Drug Evaluation
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Neuromuscular Agents / therapeutic use*
  • Pain Measurement / methods
  • Patient Satisfaction
  • Prospective Studies
  • Time Factors
  • Torticollis / drug therapy*
  • Torticollis / immunology
  • Treatment Outcome*
  • United States


  • Neuromuscular Agents
  • Botulinum Toxins, Type A