Local corticosteroid injection for carpal tunnel syndrome

BACKGROUND: Carpal tunnel syndrome is a clinical syndrome manifested by signs and symptoms of irritation of the median nerve at the carpal tunnel in the wrist. Local corticosteroid injection for carpal tunnel syndrome has been studied but its effectiveness is unknown. OBJECTIVES: To evaluate the effectiveness of local corticosteroid injection for carpal tunnel syndrome versus placebo injection or other non-surgical interventions. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Trials register (searched May 2006), MEDLINE (searched January 1966 to May 2006), EMBASE (searched January 1980 to May 2006) and CINAHL (searched January 1982 to May 2006). SELECTION CRITERIA: Randomized or quasi-randomized studies. DATA COLLECTION AND ANALYSIS: Three authors independently selected the trials and rated their overall quality. Relative risks and 95% confidence intervals were calculated for each trial and summary relative risks and 95% confidence intervals were also calculated. MAIN RESULTS: We included 12 studies with altogether 671 participants. Two high quality randomized controlled trials with altogether 141 participants demonstrated clinical improvement of carpal tunnel syndrome at one month or less following local corticosteroid compared to placebo injection (relative risk 2.58 (95% confidence intervals 1.72 to 3.87)). One trial compared local corticosteroid injection to oral corticosteroid and at 12 weeks after treatment there was significantly more improvement in the injection group (mean difference -7.10 (95% confidence intervals -11.68 to -2.52)). In one trial, the rate of improvement after one month was greater after local than systemic corticosteroid injection (relative risk 3.17 (95% confidence intervals 1.02 to 9.87)). In one trial, symptoms did not improve significantly more in the injection group at eight weeks after injection compared to treatment with anti-inflammatory medication and splinting (mean difference 0.10 (95% confidence intervals -0.33 to 0.53)). Two injections versus one injection of local corticosteroid did not provide further clinical improvement, mean difference -3.80 (95% CI -9.27 to 1.67). AUTHORS' CONCLUSIONS: Local corticosteroid injection for carpal tunnel syndrome provides greater clinical improvement in symptoms one month after injection compared to placebo. Significant symptom relief beyond one month has not been demonstrated. Local corticosteroid injection provides significantly greater clinical improvement than oral corticosteroid for up to three months. Local corticosteroid injection does not significantly improve clinical outcome compared to either anti-inflammatory treatment and splinting after eight weeks or Helium-Neon laser treatment after six months. Two local corticosteroid injections do not provide significant added clinical benefit compared to one injection.