Botulinum type A toxin complex for the relief of upper back myofascial pain syndrome: how do fixed-location injections compare with trigger point-focused injections?

OBJECTIVE: This was a prospective, randomized, double-blind, placebo-controlled, 12-week, multicenter study to evaluate the efficacy and tolerability of fixed location injections of botulinum type A toxin (BoNT-A, Dysport) in predetermined injection sites in patients with myofascial pain syndrome of the upper back.

DESIGN: Patients with moderate-to-severe myofascial pain syndrome affecting cervical and/or shoulder muscles (10 trigger points, disease duration 6-24 months) and moderate-to-severe pain intensity were randomized to BoNT-A (N = 81) or saline (N = 72).

INTERVENTION: Patients received treatment into 10 predetermined fixed injection sites in the head, neck, and shoulder (40 units of BoNT-A per site or saline, a total of 400 units of BoNT-A).

OUTCOME MEASURES: The primary efficacy outcome was the proportion of patients with mild or no pain at week 5 (responders). Secondary outcomes included changes in pain intensity and the number of pain-free days per week.

RESULTS: At week 5, 49% (37/76) of BoNT-A patients and 38% (27/72) of placebo patients had responded to treatment (P = 0.1873). Duration of daily pain was reduced in the BoNT-A group compared with the placebo group from week 5, with statistically significant differences at weeks 9 and 10 (P = 0.04 for both). Treatment was well tolerated.

CONCLUSION: Fixed-location treatment with BoNT-A of patients with upper back myofascial pain syndrome did not lead to a significant improvement of the main target parameter in week 5 after treatment. Only in week 8 were significant differences found. Several secondary parameters, such as physicians' global assessment and patients' global assessment, significantly favored BoNT-A over placebo at weeks 8 and 12.