Lidocaine patch 5 for carpal tunnel syndrome: how it compares with injections: a pilot study.

OBJECTIVES: A standard treatment option for mild-to-moderate carpal tunnel syndrome (CTS) is a local injection of anesthetic-corticosteroid, but this can be painful and may cause complications. This pilot clinical trial was designed to compare the safety and efficacy of daily applications of the lidocaine patch 5% to that of a single injection of 0.5 cc lidocaine 1% plus methylprednisolone acetate (Depo-Medrol) 40 mg.

METHODS: In this randomized, parallel-group, open-label, single-center, active-controlled, prospective pilot study, participants aged 18-75 years with clinical/electrodiagnostic evidence of CTS were randomized to receive the lidocaine patch 5% or 1 injection of 0.5 cc lidocaine 1% plus Depo-Medrol 40 mg. Outcome assessments included the Brief Pain Inventory (measuring pain intensity, relief, and interference with quality of life, Patient and Global Clinical Impression of Improvement, Global Assessment of Treatment Satisfaction, and safety.

RESULTS: Baseline characteristics of the 40 patients randomized to treatment with the lidocaine patch 5% (n=20) or injection (n=20) were similar between groups. After 4 weeks of treatment, patients in both groups reported significant changes (P<.05) in worst pain, average pain, and pain "right now." Composite interference scores, which are measures of how much patients' pain interfered with quality of life, also significantly improved in both treatment groups (patch, -13.9; injection, -16.7; P<.001 vs baseline for both groups). Eighty percent of patients in the lidocaine patch group and 59% of patients who received the injection reported being "satisfied" or "very satisfied," while investigators reported improvement in 88% of patients using the lidocaine patch and in 74% of those who received the injection. Both treatments were well tolerated, with treatment-related adverse events (AEs) reported in 3 patients in each group (15%). No systemic treatment-related AEs were observed with the lidocaine patch 5%.

CONCLUSIONS: This pilot trial demonstrated that the lidocaine patch 5% was efficacious in reducing pain associated with CTS and was well tolerated. The lidocaine patch 5% may offer patients with CTS effective, noninvasive treatment for the management of their symptoms. Further controlled trials are warranted.