Poster 156: Botulinum Toxin Type A Versus Bupivacaine Trigger Point Injections for the Treatment of Myofascial Pain Syndrome: A Randomized Double Blind Crossover Study

Abstract

Objective: To compare the effectiveness of trigger point injections using botulinum toxin type A (BTX-A) or bupivacaine in combination with a home-based exercise program in patients with myofascial pain syndrome. Design: Double-blind, crossover trial. Setting: Community physiatry practice. Participants: 18 patients with myofascial pain syndrome recruited by family physician or physiatrist. Intervention: Subjects were randomly assigned to receive initial injections of either 25U of BTX-A per trigger point or bupivacaine injections. A maximum of 8 trigger points were injected per subject. Subjects were followed until their pain returned to 75% of their preinjection pain after which there was a 2 week wash-out period. The subjects then had the same trigger points injected with the other agent. All subjects participated in a home exercise program involving static stretches of the affected muscles. Main Outcome Measures: Magnitude and duration of pain relief, effect on functional ability, satisfaction, and cost savings. Results: Both treatments were effective in reducing pain when compared with baseline (P<.05). There was, however, no significant difference between the BTX-A and bupivacaine groups in number of weeks of pain relief, magnitude of pain relief, cost savings, function, or satisfaction. Conclusions: Although both BTX-A and bupivacaine injections were effective, there was no benefit to the use of BTX-A over bupivacaine in the treatment of myofascial pain. In view of the significantly high cost of BTX-A, it is difficult to recommend this agent as a first line intervention in this condition.