• Srinivas Nalamachu, R S Crockett, Arnold R Gammaitoni, and Errol M Gould.
• Kansas City University of Medicine and Biosciences, Kansas City, Missouri, USA. nalamachu@sbcglobal.net
• MedGenMed. 2006 Jan 1;8(3):33.

ObjectivesCarpal tunnel syndrome (CTS) is a common entrapment neuropathy caused by median nerve compression. This pilot clinical trial was designed to compare the safety and effectiveness of the lidocaine patch 5% to that of naproxen 500 mg twice daily for the treatment of neuropathic pain associated with CTS.MethodsIn this 6-week, randomized, parallel-group, open-label, multicenter study, participants from 2 practice sites, aged 18 to 75 years with clinical/electrodiagnostic evidence of CTS, were randomized to receive up to 3 lidocaine 5% patches every 24 hours or naproxen 500 mg twice daily for 6 weeks. Outcome assessments included mean changes between baseline and Week 6 average pain intensity (Brief Pain Inventory [BPI]: Question 5, Average Pain Intensity [API]), an Investigator Clinical Global Impression of Improvement (CGI-I) over the course of the treatment period and a comparison of patient satisfaction (Clinical Global Assessment of Treatment [CGAT]).ResultsOne hundred patients were randomized in this study, 52 in the lidocaine patch 5% group and 48 in the naproxen 500 mg twice daily group. Significant reductions in API scores were observed between baseline and Week 6 for both lidocaine patch 5% (P < .0001) and naproxen 500 mg twice daily (P = .0004); however, there were no statistically significant differences between treatments (P = .083). There was a significant (P = .016) difference in the CGI-I for lidocaine patch 5% (51.1%) compared with naproxen 500 mg twice daily (24.3%). Whereas 71.8% of the lidocaine patch 5% patients reported being "satisfied" to "very satisfied" with the treatment, only 63.2% of naproxen 500 mg twice daily patients reported likewise, although the difference was not statistically significant. Both treatments were well tolerated. Two patients reported treatment-related adverse events in the lidocaine patch 5% group and 6 in the naproxen 500 mg twice daily group, all of which were considered mild or moderate in severity.ConclusionsThis study demonstrates that the lidocaine patch 5% is effective in significantly relieving the pain associated with CTS and is well tolerated. The patch may offer patients an effective, nonsystemic, noninvasive treatment for the management of their symptoms. Further controlled studies are warranted.

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