Therapeutic effects of lidocaine patch on myofascial pain syndrome of the upper trapezius: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: The aim of this study was to compare topical 5% lidocaine patch with placebo patch in the treatment of myofascial pain syndrome of the upper trapezius.

DESIGN: In this prospective, randomized, double-blind, placebo-controlled study, 60 participants were randomly assigned, placing 31 subjects in the 5% lidocaine patch group and 29 subjects in the placebo patch group. We used the Verbal Rating Scale (VRS), the Pressure Pain Threshold, the ranges of motion of the neck, and the Neck Disability Index to evaluate the subjective pain intensity, objective pain intensity, ranges of motion, and disability of the neck, respectively. Outcome measures were performed before (day 0) the treatment course, 12 hrs after removal of the final patch on the seventh day (day 7), and 1 wk (day 14) and 3 wks (day 28) after the completion of treatment course.

RESULTS: The characteristics of the participants did not differ at baseline. Pain intensity assessed by the VRS decreased at day 7 in both the lidocaine patch and placebo patch groups. There was no significant difference between the two groups in the VRS, the Pressure Pain Threshold, the ranges of motion, and the Neck Disability Index. At day 14, the experimental group continued to improve in the VRS (1.06), but the pain of the placebo group aggravated (VRS, 1.5). The difference is significant (P = 0.03). In addition, the Neck Disability Index in the lidocaine patch group decreased significantly as compared to that in the placebo group. The pain-relieving effect of the lidocaine patch attenuated, and it was not significantly different between the two groups at day 28 in the VRS and the Neck Disability Index. Neither the Pressure Pain Threshold nor the ranges of motion were significantly different through the periods of this study.

CONCLUSIONS: The application of the 5% lidocaine patch is probably superior to the placebo patch in relieving pain and in reducing associated neck disability for a period of longer than 1 wk for treating patients with myofascial pain syndrome of the upper trapezius.