December 1, 2009 — Low-level laser therapy (LLLT) may be helpful for chronic neck pain, according to the results of a review and meta-analysis reported in the November 13 Online First issue of The Lancet.

“Neck pain is a common and costly condition for which pharmacological management has limited evidence of efficacy and side-effects,” write Roberta T. Chow, MBBS, from the Nerve Research Foundation, Brain and Mind Research Institute, University of Sydney in Australia, and colleagues. “…LLLT is a relatively uncommon, non-invasive treatment for neck pain, in which non-thermal laser irradiation is applied to sites of pain. We did a systematic review and meta-analysis of randomised controlled trials to assess the efficacy of LLLT in neck pain.”

The reviewers searched computerized databases for studies in patients with acute or chronic neck pain comparing the efficacy of LLLT using any wavelength vs placebo or vs active control (eg, exercise). Pain intensity was the main endpoint of the study, with effect size defined as a pooled estimate of mean difference in change in millimeters using a 100-mm visual analog scale.

The search yielded 16 randomized controlled trials enrolling a total of 820 patients. Two trials in acute neck pain showed that relative risk (RR) for pain relief with LLLT vs placebo was 1.69 (95% confidence interval [CI], 1.22 - 2.33).

For chronic neck pain, the RR for pain relief with LLLT was 4.05 (95% CI, 2.74 - 5.98) in 5 trials reporting categoric data. In 11 trials reporting changes in the visual analog scale score, mean reduction in pain intensity was 19.86 mm (95% CI, 10.04 - 29.68).

In 7 trials in which follow-up continued for 1 to 22 weeks after treatment completion, short-term pain relief persisted in the medium term, with reduction of 22.07 mm (95% CI, 1742 - 26.72). Compared with placebo, LLLT was associated with adverse effects that were similar and mild.

“We show that LLLT reduces pain immediately after treatment in acute neck pain and up to 22 weeks after completion of treatment in patients with chronic neck pain,” the study authors write.

Limitations of this review include lack of accepted terminology for laser therapy and heterogeneity of conditions underlying neck pain and LLLT treatment protocols.

“Whatever the mechanism of action, clinical benefits of LLLT occur both when LLLT is used as monotherapy and in the context of a regular exercise and stretching programme,” the review authors conclude. “In clinical settings, combination with an exercise programme is probably preferable. The results of LLLT in this review compare favourably with other widely used therapies, and especially with pharmacological interventions, for which evidence is sparse and side-effects are common.”

In an accompanying comment, Dr. Jaime Guzman, from the University of British Columbia in Vancouver, Canada, notes that the number of trials sponsored by the maker of the laser devices is unclear but that there appeared to be no major publication bias.

“Today’s findings on…LLLT indicate that this non-invasive treatment provides pain relief in the short and medium term for people with neck pain,” Dr. Guzman writes. “This evidence is more solid than that for many current interventions. Although mechanisms of action and effects on function and occupational outcomes are not clearly understood and warrant further impartial study,…LLLT is an option worthy of consideration for management of non-specific neck pain.”