Efficacy and safety of a single botulinum type A toxin complex treatment (Dysport®) for the relief of upper back myofascial pain syndrome:: Results from a randomized double-blind placebo-controlled multicentre study

Botulinum type A toxin (BoNT-A) has antinociceptive and muscle-relaxant properties and may help relieve the symptoms of myofascial pain syndrome. In this study we evaluated the efficacy and tolerability of BoNT-A (Dysport (R)) in patients with myofascial pain syndrome of the upper back. We conducted a prospective, randomized, double-blind, placebo-controlled, 12-week, multicentre study. Patients with moderate-to-severe myofascial pain syndrome affecting cervical and/or shoulder muscles (>= 10 trigger points, disease duration 6-24 months) were randomized to Dysport (R) or saline. Injections were made into the 10 most tender trigger points (40 units per site). The primary outcome was the proportion of patients with mild or no pain at week 5. Secondary outcomes included changes in pain intensity and the number of pain-free days per week. Tolerability and safety were also assessed. At week 5, significantly more patients in the Dysport (R) group reported mild or no pain (51%), compared with the patients in the placebo group (26%; p = 0.002). Compared with placebo, Dysport (R) resulted in a significantly greater change from baseline in pain intensity during weeks 5-8 (p < 0.05), and significantly fewer days per week without pain between weeks 5 and 12 (p = 0.036). Treatment was well tolerated, with most side effects resolving within 8 weeks. In conclusion, in patients with upper back myofascial pain syndrome, injections of 400 Ipsen units of Dysport (R) at 10 individualised trigger points significantly improved pain levels 4-6 weeks after treatment. Injections were well tolerated. (c) 2006 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.