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) 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 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 group reported mild or no
pain (51%), compared with the patients in the placebo group (26%; p=0.002). Compared with placebo,
Dysport 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 at 10 individualised trigger points significantly improved
pain levels 4-6 weeks
after treatment.
Injections were well tolerated.