Comparison of Clinical and Electrophysiological Outcomes of Local Versus Intramuscular Steroid in Mild-to-Moderate Carpal Tunnel Syndrome: An Open-Label, Blinded Endpoint Randomized Clinical Trial

Background: In view of paucity of studies, this study compared the effects of local versus intramuscular corticosteroid injections on clinical outcomes and electrophysiological parameters in patients with mild-to-moderate carpal tunnel syndrome (CTS). Methods: This study enrolled 190 CTS patients between October 2023 to March 2025. Participants were randomized to receive either a single local injection of 40 mg methylprednisolone (MP) with 0.5 mL lidocaine at the wrist (local corticosteroid injection [LCI] arm) or a single 40 mg intramuscular (IM) MP injection in the deltoid (IM arm). The primary outcome was the Symptom Severity Scale (SSS) score at 3 months. Secondary outcomes included SSS at 1 month, Functional Status Scale (FSS), and median nerve electrophysiological changes at 1 and 3 months. Significant clinical response was defined as a reduction of ≥0.8 points in SSS or ≥0.5 in FSS. Results: Follow-up data were missing for 29 patients at 3 months. At 3 months, mean SSS score was 1.51 ( SD 0.58) in LCI and 1.64 ( SD 0.72) in IM arm ( P = .21). However, the LCI arm showed significantly greater reduction in SSS/FSS scores at 1 month. Considering patients lost to follow-up as treatment failures, response rate at 3 months was 70.5% in LCI and 72.6% in IM arm ( P = .75). Median nerve conduction results were comparable, although the LCI arm showed greater improvement at 3 months from baseline. Conclusions: In patients with mild-to-moderate CTS, LCI resulted in greater reduction in Boston Carpal Tunnel Questionnaire scores and in median nerve conductions at 1 month. However, outcome at 3 months was similar.