Myofascial pain syndrome (MPS) is described as distinct type of regional musculoskeletal pain complaint that is caused by myofascial trigger points (TrPs) within muscles or their fascia. The trigger is identified as the presence of a taut band in the muscle, tenderness on compression in a point of the band. There are variable estimates from epidemiologic studies on the incidence and prevalence of MPS due to the lack of universally accepted diagnostic criteria for the syndrome, in addition most of the epidemiologic data available pertain to musculoskeletal pain in general. It has been estimated that in a general internal medicine practice 30% of patients complained primarily from myofascial pain, and that for 85% of patients admitted to a comprehensive pain center the primary diagnosis was myofascial pain. Treatment of MPS involves treatment of TrPs and the removal of causative/perpetuating factors. Muscle stretch, TrP injection (such as injection of botulinum toxin, or anaesthetic), acupuncture, therapeutic ultrasound, and drug therapy are treatments currently adopted for the deactivation of TrPs. Correction of perpetuating factors include amending incorrect muscle activity and any abnormal postural issues, as well as, where possible, correcting all possible anatomical defects causing muscle imbalance.

Botulinum Toxin A (BoNTA) is a purified neurotoxin complex produced from the fermentation of Clostridium botulinium type A. BoNTA inhibits acetylcholine release into the neuromuscular junction, resulting in reduction in muscular contractions. In Canada BoNTA is marketed in three distinct formulations, Botox, Dysport, and Xeomin. BoNTA is used off-label for the treatment of MPS. The objective of this review is to evaluate the clinical effectiveness of BoNTA in the treatment of MPS.

This report is an update to a CADTH Rapid Response report published in October 2008.

Contents

• CONTEXT AND POLICY ISSUES
• RESEARCH QUESTION
• KEY FINDINGS
• METHODS
  • Literature Search Strategy
  • Selection Criteria and Methods
  • Exclusion Criteria
  • Critical Appraisal of Individual Studies
• SUMMARY OF EVIDENCE
  • Quantity of Research Available
  • Summary of Study Characteristics
  • Summary of Critical Appraisal
  • Summary of Findings
  • Limitations
• CONCLUSIONS AND IMPLICATIONS FOR DECISION OR POLICY MAKING
• REFERENCES
• APPENDIX 1 Selection of Included Studies
• APPENDIX 2 CHARACTERISTICS OF THE INCLUDED STUDIES
• APPENDIX 3 SUMMARY OF STUDY STRENGTHS AND LIMITATIONS
• APPENDIX 4 MAIN STUDY FINDINGS AND AUTHORS’ CONCLUSIONS

Disclaimer: The Rapid Response Service is an information service for those involved in planning and providing health care in Canada. Rapid responses are based on a limited literature search and are not comprehensive, systematic reviews. The intent is to provide a list of sources of the best evidence on the topic that CADTH could identify using all reasonable efforts within the time allowed. Rapid responses should be considered along with other types of information and health care considerations. The information included in this response is not intended to replace professional medical advice, nor should it be construed as a recommendation for or against the use of a particular health technology. Readers are also cautioned that a lack of good quality evidence does not necessarily mean a lack of effectiveness particularly in the case of new and emerging health technologies, for which little information can be found, but which may in future prove to be effective. While CADTH has taken care in the preparation of the report to ensure that its contents are accurate, complete and up to date, CADTH does not make any guarantee to that effect. CADTH is not liable for any loss or damages resulting from use of the information in the report.