Multicenter, Randomized, Placebo-controlled Crossover Trial Evaluating Topical Lidocaine for Mechanical Cervical Pain

Abstract

Background There are few efficacious treatments for mechanical neck pain, with controlled trials suggesting efficacy for muscle relaxants and topical non-steroidal anti-inflammatory drugs. Although studies evaluating topical lidocaine for back pain have been disappointing, the more superficial location of the cervical musculature suggests a possible role for topical local anesthetics. Methods We performed a randomized, double-blind, placebo-controlled crossover trial at 4 U.S. military, Veterans Administration, academic and private practice sites in which 76 patients were randomized to receive either placebo followed by lidocaine patch for 4-week intervals (group 1) or a lidocaine-placebo patch sequence. The primary outcome measure was mean reduction in average neck pain, with a positive categorical outcome designated as a ≥2-point reduction in average neck pain coupled with a ≥5/7 score on the Patient Global Impression of Change scale at the 4-week endpoint. Results For the primary outcome, the median reduction in average neck pain score was -1.0 (IQR -2.0, 0.0) for the lidocaine phase vs. -0.5 (IQR -2.0,.0) for placebo treatment (p=0.17). 27.7% of patients experienced a positive outcome during lidocaine treatment vs. 14.9% during the placebo phase (p=0.073). There were no significant differences between treatments for secondary outcomes, though a carryover effect on pain pressure threshold was observed for the lidocaine phase (p=0.015). 27.5% of patients in the lidocaine group and 20.5% in the placebo group experienced minor reactions, the most common of which was pruritis (p=0.036). Conclusions The differences favoring lidocaine were small and non-significant, but the trend towards superiority of lidocaine suggests more aggressive phenotyping and applying formulations with greater penetrance may provide clinically meaningful benefit.