• R Norman Harden, Jerod Cottrill, Christine M Gagnon, Todd A Smitherman, Stephan R Weinland, Beverley Tann, Petra Joseph, Thomas S Lee, and Timothy T Houle.
• Center for Pain Studies, Rehabilitation Institute of Chicago, 446 E. Ontario, Chicago, IL 60611, USA.
• Headache. 2009 May 1;49(5):732-43.

ObjectiveTo evaluate the efficacy of botulinum toxin A (BT-A) as a prophylactic treatment for chronic tension-type headache (CTTH) with myofascial trigger points (MTPs) producing referred head pain.BackgroundAlthough BT-A has received mixed support for the treatment of TTH, deliberate injection directly into the cervical MTPs very often found in this population has not been formally evaluated.MethodsPatients with CTTH and specific MTPs producing referred head pain were assigned randomly to receive intramuscular injections of BT-A or isotonic saline (placebo) in a double-blind design. Daily headache diaries, pill counts, trigger point pressure algometry, range of motion assessment, and responses to standardized pain and psychological questionnaires were used as outcome measures; patients returned for follow-up assessment at 2 weeks, 1 month, 2 months, and 3 months post injection. After 3 months, all patients were offered participation in an open-label extension of the study. Effect sizes were calculated to index treatment effects among the intent-to-treat population; individual time series models were computed for average pain intensity.ResultsThe 23 participants reported experiencing headache on a near-daily basis (average of 27 days/month). Compared with placebo, patients in the BT-A group reported greater reductions in headache frequency during the first part of the study (P = .013), but these effects dissipated by week 12. Reductions in headache intensity over time did not differ significantly between groups (P = .80; maximum d = 0.13), although a larger proportion of BT-A patients showed evidence of statistically significant improvements in headache intensity in the time series analyses (62.5% for BT-A vs 30% for placebo). There were no differences between the groups on any of the secondary outcome measures.ConclusionsThe evidence for BT-A in headache is mixed, and even more so in CTTH. However, the putative technique of injecting BT-A directly into the ubiquitous MTPs in CTTH is partially supported in this pilot study. Definitive trials with larger samples are needed to test this hypothesis further.

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