EVALUATION OF BOTULINUM TOXIN TYPE B (MYOBLOC) FOR MYOFASCIAL PAIN: RESULTS OF A PRELIMINARY PATIENT SURVEY

Abstract

Botulinum toxin type B (Myobloc; BoNT-B) is indicated for the treatment of cervical dystonia. The toxin prevents acetylcholine release presynaptically at the neuromuscular junction, producing a dose-dependent degree of paralysis in injected muscles. This effect has been found to alleviate symptoms, including pain associated with cervical dystonia, and suggests that BoNT-B may be useful for the treatment of other painful conditions. We treated six patients (2 male; 4 female) with myofascial pain syndrome with BoNT-B injections (total dose 5000–10,000 U), and report of the results of a follow-up telephone survey conducted 4 to 16 weeks post-injection. The four female patients had pain in the neck/shoulders and were injected in that region. The two male patients were injected in the lower back muscles. The survey included questions about the severity of pain pre- and post-injection (0–10 numeric rating scale), range of motion (ROM), need for use of pain medications, and change in functioning. The severity of pain pre-injection averaged about 7/10. All patients had a very positive response to treatment. Following BoNT-B injection, pain severity decreased an average of −3.1/10. 5/6 patients had improvements in ROM, and 4/6 patients reported a decrease in number of pain medications needed. There were improvements in the ability to perform certain basic tasks (eg, brushing teeth) as well as other activities (eg, running). Overall, BoNT-B was well-tolerated. Some patients experienced flu-like symptoms that subsided after about 1 week. All patients indicated that treatment was very helpful and would be interested in receiving a re-injection. Our preliminary findings support further investigation of BoNT-B in the treatment of myofascial pain. Support of Elan Pharmaceuticals is gratefully acknowledged.