Open-label, Multicenter, Randomized Study Investigating the Efficacy and Safety of Botulinum Toxin Type A in the Treatment of Myofascial Pain Syndrome in the Neck and Shoulder Girdle

Objectives: To evaluate two doses of botulinum toxin A [BoNT-A] for the treatment of chronic myofascial pain syndrome [MPS]. Methods: A 12-week, open-label, randomized study in which patients [N = 163] with MPS in the neck and shoulder girdle muscles were treated with intramuscular injections of 200 U [25 U/trigger point [TrP]] or 320 U [40 U/TrP] BoNT-A. Results: At Week 7, 34.8 percent of BoNT-A 200 U and 34.3 percent of BoNT-A 320 U patients had clinically significant improvement in pain. Treatment was well-tolerated. Conclusions: Both doses provided effective relief from chronic MPS; benefits were maintained for at least three months.