Efficacy of a 0.1% capsaicin hydrogel patch for myofascial neck pain: a double-blinded randomized trial

The objective of this study was to evaluate the efficacy of a hydrogel patch containing capsaicin 0.1% compared with a placebo hydrogel patch without capsaicin to treat chronic myofascial neck pain.

The study was designed as a double-blinded randomized controlled trial. Setting.  The study was set at Kyung-hee University Hospital at Gangdong, Korea.

Sixty-one participants between 18 and 65 years with at least 3 months duration of neck pain and a clinical presentation of myofascial pain syndrome were enrolled in the study from September 1 to November 20, 2010. Interventions.  Participants received capsaicin 0.1% hydrogel patches or control hydrogel patches without capsaicin according to the randomization scheme. All participants were instructed to apply one patch to each side of the neck and shoulder girdle overlying the point of maximal pain for 12 hours daily during the duration of the 4-week study.

Each participant completed five surveys at baseline, at 2 weeks after the start of treatments, and at the conclusion of the 4-week study. The primary outcome measure was visual analog scale (VAS). Other outcome measures included the Neck Disability Index (NDI), Beck's Depression inventory (BDI), Short Form 36 Korean version, and Euroqol 5-D.

Fifty-seven patients completed the study. The mean VAS, NDI, and BDI scores were significantly decreased at 2 and 4 weeks after the start of the intervention in both groups. There was no significant difference between the two groups in any of the outcome measures.

Future research may help to discern specific effects of capsaicin, trigger point stimulation by application of the patch, and the placebo effect.