An open-label pilot study evaluating the effectiveness of the heated lidocaine/tetracaine patch for the treatment of pain associated with carpal tunnel syndrome.

Objectives: Carpal tunnel syndrome (CTS) is a common entrapment neuropathy of the median nerve at the wrist that is characterized by pain, paresthesias, weakness, and loss of dexterity. This pilot study was conducted to evaluate the heated lidocaine/tetracaine patch (HLT patch) as a conservative treatment for pain of CTS.
Methods: Twenty adult patients (mean age = 44 ± 12 years) with pain secondary to unilateral CTS and electrodiagnostic evidence of mild-to-moderate CTS enrolled in this open-label study. Patients were treated with a single HLT patch placed over the junction of forearm and wrist on the palmar aspect of the wrist twice daily (morning and evening at 12-hour intervals) for 2 hours. At baseline and during the 2-week study, patients graded their pain intensity with an 11-point numerical rating scale (0 = no pain, 10 = worst imaginable pain). Pain interference with general activity, work, and sleep was evaluated with a similar 0-to-10-point scale.
Results: Fifteen patients completed the 14-day treatment period. Mean average pain intensity score decreased from 5.1 ± 1.5 at baseline to 2.5 ± 1.6 at end of study in the per-protocol population (P < 0.001). Two-thirds of the patients demonstrated clinically meaningful pain relief (≥ 30% reduction in average pain score), with 40% of the patients reaching this threshold by the third treatment day. Similar improvements were observed for pain interference scores. The HLT patch was generally well tolerated.
Conclusion: The HLT patch resulted in clinically meaningful reduction in pain intensity in the majority of patients with mild-to-moderate CTS and may represent a targeted nonsurgical treatment for pain associated with CTS.
(© 2013 World Institute of Pain.)