Local corticosteroid injection versus surgery for carpal tunnel syndrome.

Background: Carpal tunnel syndrome (CTS) is a very common clinical syndrome manifested by signs and symptoms of irritation of the median nerve at the carpal tunnel in the wrist. Direct and indirect costs of CTS are substantial, with estimated costs of two billion US dollars for CTS surgery in the USA alone. Local corticosteroid injection has been used as a non-surgical treatment for CTS for many years, but its effectiveness is still debated.

Objectives: To evaluate the benefits and harms of corticosteroids injected in or around the carpal tunnel for the treatment of carpal tunnel syndrome (CTS) compared to surgery.

Search methods: We used standard, extensive Cochrane search methods. We searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, and WHO ICTRP. The latest search was 26 May 2022.

Selection criteria: We included randomised controlled trials (RCTs) or quasi-randomised trials of adults with CTS that included at least one comparison group of local corticosteroid injection (LCI) into the wrist and one group of any surgical intervention.

Data collection and analysis: We used standard Cochrane methods. Our primary outcome was 1. improvement in symptoms at up to three months of follow-up. Our secondary outcomes were 2. functional improvement, 3. improvement in symptoms at greater than three months of follow-up, 4. improvement in neurophysiological parameters, 5. improvement in imaging parameters, 6. improvement in quality of life and 7.

Adverse events: We used GRADE to assess the certainty of evidence for each outcome.

Main results: We included seven studies involving 569 'hands' (although two studies had unusable data for quantitative analyses). All studies used a one-time LCI as a comparator, using several different types and doses of corticosteroids. In every study, for both surgery and LCI groups, all our primary and secondary outcomes showed improvement from pre- to post-treatment. However, evidence from the combined analysis was too uncertain for us to draw reliable conclusions for the comparison of surgical treatment versus LCI with respect to our primary outcome of symptom relief at up to three months' follow-up (standardised mean difference (SMD) 0.63, 95% confidence interval (CI) -0.61 to 1.88; I² = 95%; 5 trials, 305 participants; very low-certainty evidence). Findings with respect to secondary outcome measures of symptom relief at greater than three months' follow-up (SMD 0.94, 95% CI -0.31 to 2.19; I² = 93%; 4 trials, 235 participants), functional improvement at up to three months' follow-up (SMD -0.11, 95% CI -0.94 to 0.72; I² = 84%; 3 trials, 215 participants) and functional improvement at greater than three months' follow-up (SMD 0.19, 95% CI -1.22 to 1.59; I² = 93%; 3 trials, 185 participants) were also uncertain (very low-certainty evidence) and showed no clear advantage for surgery or LCI. Surgery may improve neurophysiology (median nerve distal motor latency) more than LCI (mean difference (MD) 0.87 ms, 95% CI 0.32 to 1.42; I² = 72%; 3 trials, 162 participants; low-certainty evidence). Evidence for quality of life and adverse events was also uncertain; quality of life (EuroQol-5D-3L) may be slightly improved after LCI than after surgery (the difference may not be clinically important) (MD 0.07, 95% CI 0.02 to 0.12; 1 trial, 38 participants; very low-certainty evidence) and there may be fewer adverse events with LCI than with surgery (risk ratio (RR) 0.34, 95% CI 0.04 to 3.26; 3 trials, 112 participants; very low-certainty evidence).

Authors' conclusions: The evidence comparing LCI to surgery for CTS, either in the short term or up to 12 months' follow-up, is too uncertain for any reliable conclusions to be drawn.