When is botulinum toxin indicated in the treatment of myofascial pain syndrome?

Updated: Mar 11, 2019
  • Author: Heather Rachel Davids, MD; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Indications for botulinum treatment are not entirely clear for patients with myofascial pain syndrome. These patients may be considered candidates for botulinum toxin if they have not responded to traditional forms of treatment, have had a chronic refractory problem for 3 months or longer, have had a complete medical workup to rule out other nonmuscular causes for their pain, and have clearly defined TrPs.

The clinician should proceed with caution before considering using botulinum toxin in the treatment of a patient with myofascial pain. Remember that use of BoNT-A for the treatment of pain is only approved in the United States for pain related to cervical dystonia. Use of BoNT-A for myofascial pain, therefore, is an off-label use and may be considered most appropriate only for patients with a condition that does not respond to, or is judged inappropriate for, more conservative treatment. Factors that may identify a myofascial pain syndrome as potentially responding favorably to botulinum toxin injections include muscle hypertrophy, neurogenic and/or vascular compression, anatomic localization that isolates the target muscle from other structures, and more than 1 outcome measure to determine the efficacy of treatment. One such condition that meets these criteria is termed piriformis muscle syndrome (PMS).

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