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Reference: (Ann Intern Med 2013 Sep 3;159(5):309), (level 1 [likely reliable] evidence)
When conservative treatments such as wrist splinting fail to provide lasting relief, many patients with carpal tunnel syndrome (CTS) opt for surgery. Local steroid injections are also a common treatment, but injections have not been shown to be effective for more than 1 month in high-quality randomized trials (Cochrane Database Syst Rev 2007 Apr 18;(2):CD001554). A new randomized trial evaluated the efficacy of steroid injections for reducing symptom severity and need for surgery.
A total of 111 adults aged 18-70 years with mild to moderate CTS who had been unsuccessfully treated with wrist splints were randomized to local injections with methylprednisolone (80 mg vs. 40 mg) vs. placebo. Local anesthesia with lidocaine 1 mL was given with all injections. Symptoms were assessed using the CTS symptom severity scale, which measures 11 items including severity, frequency, and duration of pain at day and night, and numbness or tingling (5-point scale). Patients could choose to have surgery after 3 months.
The primary outcomes were rates of surgery at 1 year and symptom severity scores at 10 weeks. In the placebo group, 92% had had surgery by the 12 month evaluation . The surgery rate with 80 mg methylprednisolone was 73% (p = 0.042 vs. placebo, NNT 6). In the 40 mg methylprednisolone group, 81% had surgery, but this rate was not significantly different from placebo. Symptom severity at 10 weeks was significantly reduced with both doses of prednisolone compared to placebo. The mean reductions were 0.9 points with methylprednisolone 80 mg (p = 0.003 vs. placebo), 1.17 points with methylprednisolone 40 mg (p < 0.001 vs. placebo), and 0.3 points with placebo. There were no significant differences in CTS symptom severity scores, disability scores, quality of life, or treatment satisfaction at 1 year.
Despite the significant benefit from the steroid injection, nearly 3/4 of the 80 mg methylprednisolone group did ultimately have surgery. Nonetheless, for clinicians counseling their patients with persistent carpal tunnel syndrome symptoms, this trial demonstrates that in addition to providing short-term symptom relief, the injection may result in avoiding surgery in a sizable minority of patients.
For more information, see the Carpal tunnel steroid injection and Carpal tunnel syndrome topic in DynaMed.