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

Background:There are few efficacious treatments for mechanical neck pain, with controlled trials suggesting efficacy for muscle relaxants and topical nonsteroidal 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:This study was a randomized, double-blind, placebo-controlled crossover trial performed at four 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-then-placebo patch sequence. The primary outcome measure was mean reduction in average neck pain, with a positive categorical outcome designated as a reduction of at least 2 points in average neck pain coupled with at least a 5-point score of 7 points 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 (interquartile range, -2.0, 0.0) for the lidocaine phase versus -0.5 (interquartile range, -2.0, 0.0) for placebo treatment (P = 0.17). During lidocaine treatment, 27.7% of patients experienced a positive outcome versus 14.9% during the placebo phase (P = 0.073). There were no significant differences between treatments for secondary outcomes, although a carryover effect on pain pressure threshold was observed for the lidocaine phase (P = 0.015). A total of 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 = 0.36).Conclusions:The differences favoring lidocaine were small and nonsignificant, but the trend toward superiority of lidocaine suggests more aggressive phenotyping and applying formulations with greater penetrance may provide clinically meaningful benefit. In this multisite, double-blind, crossover randomized clinical trial in civilian, active-duty military, and veteran patients with non-neuropathic mechanical neck pain, a 4-week lidocaine patch treatment was not associated with greater reduction in group-level average neck pain (-1 point) than placebo (-0.5 point). Exploratory analysis revealed that the lidocaine was associated with decreased pain sensitivity upon standardized mechanical pain testing, with higher pressure pain thresholds observed after lidocaine treatment than after placebo. Larger studies investigating specific phenotypic patient- or disease-level characteristics associated with greater response are needed in the future.