• 
• 

Three Part Question

[In patients with chronic simple low back pain] are [muscle relaxants better than placebo] at [decreasing pain, improving mobility and speeding a return to normal activities (e.g. work)]

Clinical Scenario

A 55 year old woman presents to her GP with lower back pain radiating to her right buttock. The pain has been present for 4 months and you have seen her on many occasions with persistance of symptoms. She has been investigated with an MR scan which revealed no specific pathology except moderate OA changes. Neurological examination is normal and there are no "red flag" symptoms or signs to suggest that this is anything other than simple low back pain. You have treated her with oral paracetamol and NSAIDs but she now requests that you supply some muscle relaxants as her friends have told her that it is probably spasm causing her pain. You wonder if this is a good idea.

Search Strategy

OVID Medline on the www. via ATHENS 1966-2005
[muscle relaxant$ or exp muscle relaxants, central/ or antispasticity.mp or benzodiazepines.mp or exp.BENZODIAZEPINES or antispasmodic.mp. or exp Parasympatholytics/] and [back pain.mp or exp back pain/ or exp low back pain or lumbar pain.mp]

Search Outcome

Medline: 57 papers were found of which 2 were relevant to the clinical question

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
van Tulder 2003 Canada	Review of papers examining the use of muscle relaxants in patients with simple low back pain. Only RCTs and CCTs were included in the article.	Systematic review	Benzodiazepines in chronic low back pain	2 high quality trials. strong evidence for short term benefit. Pain intensity RR 0.82 in favour of benzos after 5-7 days, and 0.71 at 10 to 14 days.	This is a well conducted review article. There is also a Cochrane review by the same authors on the same subject. The outcomes in individual trials are often disparate making grouping of results difficult.
			Nonbenzodiazepines in chronic low back pain	3 trials, Two high quality trials showed benefit to muscle relaxants for short term (7-21 days) pain relief
Bernstein et al 2004 USA	1633 patients with low back pain. Recruited from community practitioners. Observed to determine if the use of muscle relaxants was associated with a more rapid recovery. No interventions were made by the authors on the care of the patients.	Observational cohort.	Baseline data on patient mix	24% had sciatica. average pain was 5.4 on a 10 point scale. Average Roland baseline score was 11.2. Mean time to functional recovery (if recovered) was 16.2 days.	Only looked at time to return to normal function. benefit in treatment may be in relief of symptoms only which would be missed on this study. Purely observational study which is prone to a great deal of bias. Groups clearly different at baseline with users of muscle relaxants apparently having a greater degree of illness (though this is adjusted for in the Cox analysis). Mostly acute pain.
			Use of muscle relaxants	49% of patients used muscle relaxants
			Statistically significant differences in patient characteristics between users and non users	Users were on average 2.3 years younger (p=0.012); female 50% vs 45%; on workers compensation 34% vs 28%; or if they had a higher pain score, roland disability score or if they took longer to recover. They were less likely to be used if the patient had seen a chiropracter as initial provide 18% vs 55%;
			Time to achieve functional recovery on Cox proportional hazards model.	No difference in recovery rates between those using muscle relaxants and those not.

Comment(s)

The evidence suggestst that muscle relaxants do show benefit in chronic back pain but that the incidence of side effects is high. It therefore seems logical that their use is restricted to situations where an increase in mobility is required to achieve a specific aim, e.g. to start an exercise program.

Clinical Bottom Line

Muscle relaxants show a benefit in chronic back pain, but the incidence of side effects is high.

Level of Evidence

Level 1 - Recent well-done systematic review was considered or a study of high quality is available.

References

1. 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;28:1978-1992
2. Bernstein E, Carey TS, Garrett JM. Bernstein E, Carey TS, Garrett JM. Spine 2004;29:1346-1351