Local Corticosteroid Injection vs. Placebo for Carpal Tunnel Syndrome

Are local corticosteroid injections into the carpal tunnel safe and effective for the treatment of carpal tunnel syndrome (CTS)?

Local corticosteroid injection is effective for reducing symptoms and improving function and quality of life in patients with mild to moderate CTS, with benefits lasting up to six months. Patients who receive local corticosteroid injections have a reduced need for surgery at 12 months. Although serious adverse events have been reported, they are rare.¹ (Strength of Recommendation: B, limited-quality patient-oriented evidence.)

CTS is the most common peripheral nerve entrapment syndrome worldwide, affecting 1% to 5% of the adult population.^2,3 Common symptoms are numbness, tingling, and pain in the median nerve distribution. Treatment for CTS includes conservative modalities such as lifestyle modifications, splinting, oral corticosteroids, other oral medications, physical therapy, therapeutic ultrasound, and more invasive procedures such as injected corticosteroids and surgical decompression. This review evaluated the benefits of treating CTS with local corticosteroid injections.¹

This Cochrane review included 14 randomized controlled trials (RCTs) and quasi-randomized trials involving 994 adults with CTS in hospital-based clinics across North America, Europe, Asia, and the Middle East. The treatment intervention was a local corticosteroid injection of any type or dose with or without adding a local anesthetic into or near the carpal tunnel. Many different dosing protocols and injection protocols were included. The comparison groups involved saline injection (six studies), no treatment (one study), local anesthetic injection (two studies), or a combination of local corticosteroid injections plus splinting vs. splinting alone (five studies). Symptom scores were evaluated using several validated participant-reported outcome measures for CTS, including the Boston Carpal Tunnel Questionnaire. The review did not define mild, moderate, and severe CTS.

Local corticosteroid injections improved symptom scores in the first three months (standardized mean difference [SMD] = −0.77; 95% CI, −0.94 to −0.59; eight RCTs; n = 579; moderate-certainty evidence). Local corticosteroid injections also improved symptom scores in the first six months (SMD = −0.58; 95% CI, −0.89 to −0.28; four RCTs; n = 234; moderate-certainty evidence). Improvement in function at up to three months favored local corticosteroid injections (SMD = −0.62; 95% CI, −0.87 to −0.38; seven RCTs; n = 499; moderate-certainty evidence). Quality of life, measured at up to three months using the Short-Form 6 Dimensions questionnaire (scale from 0.29 to 1.0; higher is better), was also improved slightly in patients who received local corticosteroid injections (mean difference = 0.07; 95% CI, 0.02 to 0.12; one RCT; n = 111; moderate-certainty evidence). In addition, local corticosteroid injections slightly reduced the requirement for CTS surgery at 12 months (risk ratio = 0.84; 95% CI, 0.72 to 0.98; one RCT; n = 111; moderate-certainty evidence). Although the authors could not qualify this comment, they did note that patients who received higher doses of steroids seemed to have symptom relief that lasted longer than those who received lower doses.

Adverse events were uncommon, although only about one-half of the studies reported them. Four studies (n = 229) reported no adverse events, although three studies (n = 220) did not specifically address the occurrence of adverse events. One study reported two of the 364 injections resulted in severe pain, which resolved over several weeks, and one of the 364 injections resulted in a cool, pale hand that resolved within 20 minutes. One study (n = 111) reported no serious adverse events; however, 65% of the corticosteroid group and 16% of the placebo group experienced mild to moderate pain lasting less than two weeks, and 9% experienced localized swelling lasting less than two weeks.