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A011
October 13, 2012
8:00:00 AM - 9:30:00 AM
Room 103A
Efficacy of BOTOX Injections for Bilateral Posterior Neck and Cervical Muscle Pain
Jeffrey Loh, M.D., Andrea Nicol, M.D., F. Michael Ferrante, M.D.
UCLA, Santa Monica, California, United States
Introduction

Myofascial pain syndrome (MPS) is a regional condition of muscle pain and stiffness characterized by the presence in affected musculature of myofascial trigger points. Therapies for myofascial pain include pharmacotherapy, injection therapy, physical therapy, and behavioral modification. Muscle relaxation may aid physical therapy in reversing distortion and enabling repair of damaged tissues. Botulinum toxin type A (BoNT-A) inhibits the release of acetylcholine at the neuromuscular junction leading to sustained muscle relaxation. While the efficacy of BoNT-A in the treatment of spasticity and dystonia are supported by literature, BoNT-A for the treatment of MPS remains unclear.

Methods

A single-center, double-blind, placebo-controlled, enriched trial was performed on 118 subjects with cervicothoracic muscle pain for greater than 8 weeks. Subjects washed out their pain medications 2 weeks prior to their baseline visit, except for ibuprofen and tramadol. Subjects with a Visual Numerical Pain Score (VNS) > 4 were injected with BoNT-A. At 6 weeks post-injection, subjects with at least a 50% decrease in their VNS were randomized into one of two treatment groups. At 14 weeks post-injection, patients in group 1 received a second BoNT-A injection into affected muscles, while those in group 2 received an injection of saline (placebo). Both groups were followed an additional 12 weeks. Outcomes were assessed using the McGill Questionnaire, Brief Pain Inventory, Neck Disability Index, and SF-36 forms. Demographic data were compared using chi-square analysis, Fisher’s exact test, and Student’s t-test. Two-way repeated measures ANOVA was used to analyze outcomes.

Results

Of 118 subjects studied, 54 were categorized as responders, 57 as non-responders, and 7 were excluded. Responders were randomized, with 29 patients receiving a second injection of BoNT-A and 25 patients receiving an injection of saline. No significant differences were found between treatment groups. There was a significant improvement in the number of headaches per week in patients who received BoNT-A compared to placebo (P = 0.043). Quality of life showed improvement in general activity (P = 0.045), sleep (P = 0.021), and enjoyment (P = 0.041) for subjects who received BoNT-A. BoNT-A subjects also showed a decrease in total number of posterior trigger points (P = 0.03).

Discussion

While previous studies have suggested safety and efficacy of BoNT-A for the treatment of MPS, these studies suffered from methodologic flaws: lack of power, retrospective design, and lack of blinding. This study followed an enrichment protocol that eliminates many of these flaws. The results of this study demonstrate that there is a statistically and clinically significant improvement in MPS after a BoNT-A injection.

This study also shows that while most subjects’ pain recurs following a BoNT-A injection, pain scores fail to reach their baseline state. In subjects who received BoNT-A a second time, the efficacy of the treatment was not as large as the first injection, indicating a potentially prolonged benefit of BoNT-A in patients categorized as responders.

Conclusion

BoNT-A injections are associated with a clinically and statistically significant improvement in MPS. However, further large-scale, well-powered, double-blind, placebo controlled, randomized trials will be necessary for proof of concept.

Copyright © 2012 American Society of Anesthesiologists