Comparison of Distal and Proximal Local Steroid Injection for Carpal Tunnel Syndrome: a Systematic Review and Meta-analysis of Randomized Controlled Trials

Introduction: Local steroid injection (LSI) in the carpal tunnel is a mainstay of conservative treatment in patients with carpal tunnel syndrome (CTS). Currently, clinicians generally perform a conventional proximal approach (PA) or novel distal approach (DA) for LSI. Recent systematic reviews comparing the two injection methods are lacking. This systematic review and meta-analysis aimed to assess whether LSI using the DA was superior to PA in treating patients with CTS. Methods: Databases including Pubmed, Embase, and the Cochrane library were searched up to 30 May 2022 to identify relevant randomized controlled trials (RCTs) comparing the DA with the PA steroid injection in patients with CTS. The outcomes mainly included Boston Carpal Tunnel Questionnaire Symptom Severity Scale (BCTQs) and Functional Status Scale (BCTQf), visual analog scores (VAS), electrophysiological outcomes, pain of injection, duration of injection, or adverse events. Results: Five RCTs involving 339 patients were identified. Pooled analysis showed that the DA group took less time [mean difference (MD) −19.91; 95% CI −34.48 to −5.35; P = 0.007] and acquired better sensory nerve action potential amplitude [standardized mean difference (SMD) −0.37; 95% CI −0.62 to −0.11; P = 0.005]. The two groups were not significantly different in terms of BCTQs and BCTQf, VAS, other electrophysiological outcomes, pain of injection, or adverse events (P > 0.05). Conclusion: Although providing similar improvement in pain relief or function improvement, the distal approach is superior to the proximal approach in terms of timing, without increasing other side effects. Further high-quality randomized studies are required to confirm these results.