Are Muscle Relaxants Effective for Treating Low Back Pain?

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Muscle relaxants have shown to be effective for managing acute low back pain.
Muscle relaxants have shown to be effective for managing acute low back pain.

Researchers at the University of Sydney, Australia, performed a meta-analysis to determine whether muscle relaxants, which are commonly prescribed to manage low back pain (LBP), are efficacious in treating this common complaint.1

The leading cause of disability worldwide, LBP affects 23% of the population.2 Benzodiazepines (including diazepam) and muscle relaxants (including skeletal muscle relaxants carisoprodol and cyclobenzaprine) are the most commonly prescribed medications for LBP in the United States. However, it is recommended that benzodiazepines or muscle relaxants be prescribed as second-line treatment to manage LBP if nonsteroidal anti-inflammatory drugs (NSAIDs) or opioid analgesics prove ineffective.3, 4


The authors of the article, published online in the European Journal of Pain, searched medical databases, including Medline, EMBASE, and Central (n=10,309 searches), for randomized controlled trials (RCTs) investigating the efficacy of muscle relaxants and benzodiazepines for nonspecific LBP. A total of 15 studies (3362 participants) passed quality assessment and were considered in this meta-analysis; all were for muscle relaxants, none for benzodiazepines.

In this analysis, nonspecific LBP followed the definition laid out in a 2003 study: “Pain localized between the scapulas and inferior gluteal folds that may or may not radiate down towards the knees, for which specific aetiologies such as infections, neoplasms, metastases, osteoporosis, fractures, rheumatological disorders, neurologic disorders and other relevant pathologic entities have been ruled out clinically.”5

The primary outcome for the RCTs was pain intensity, which was measured from 0 to 100 using visual analogue and numerical rating scales. Disability was assessed using the Oswestry Disability Index and the Roland-Morris Disability Questionnaire scores.

In 5 out of 15 trials included in the meta-analysis, muscle relaxants significantly produced pain relief for acute LBP (n=496, P <.001). Evidence investigating the effects of muscle relaxants on chronic LBP or disability was lacking. Information on adverse events associated with muscle relaxants vs placebo was available for 6 trials. The median rate of adverse events—which included headache, nausea, and dizziness—was similar to placebo (P =.5).

Muscle relaxants are both efficacious in treating acute low back pain and devoid of serious side effects, and should therefore be preferred as first-line of treatment. Additional studies are required to investigate whether they constitute appropriate treatment for chronic low back pain.

Muscle relaxants are both efficacious in treating acute low back pain and devoid of serious side effects, and are therefore indicated as first-line treatment. Additional studies are required to investigate whether they constitute appropriate treatment for chronic low back pain.

References

1. Abdel Shaheed C, Maher CG, Williams KA, McLachlan AJ. Efficacy and tolerability of muscle relaxants for low back pain: systematic review and meta-analysis. Eur J Pain. 2016 Jun 22. DOI: 10.1002/ejp.907. [Epub ahead of print]

2. Lim SS, Vos T, Flaxman AD, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2224-2260.

3. See S, Ginzburg R. Choosing a skeletal muscle relaxant. Am Fam Physician. 2008;78(3):365-370.

4. American Pain Society: Guidelines for the Evaluation and Management of Low Back Pain – Evidence Review http://americanpainsociety.org/uploads/education/guidelines/evaluation-management-lowback-pain.pdf

5. Van Tulder MW, Touray T, Furlan AD, Solway S, Bouter LM. Muscle relaxants for nonspecific low back pain: a systematic review within the framework of the Cochrane collaboration. Spine. 2003;28(17):1978-1992.


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