1. In patients with primary idiopathic carpal tunnel syndrome (CTS), injection with either 40mg or 80mg methylprednisolone is associated with a significant reduction in symptom severity at 10 weeks.
2. Injection with 80mg of methylprednisolone was associated with modestly lower rates of surgery at 1-year. This treatment, however, did not completely preclude the need for surgery, as 73% of these patients still eventually required surgery.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Carpal tunnel syndrome (CTS) is a common condition, and most patients who initially try conservative management (i.e. wrist splinting) eventually require surgery. Despite generally good outcomes, surgery for CTS is not without risks. Thus, these patients may benefit from effective non-surgical treatment options. Steroid injections are commonly used in clinical practice. However, few randomized control trials have investigated the long-term benefits of treatment. This study found that steroid-naïve patients with primary idiopathic CTS who received either a single 40mg or 80mg methylprednisolone injection had significantly greater improvement in symptoms at 10 weeks than those who received placebo. This effect, however, was no longer significant at 1 year and the effect was not noted to be dose-dependent. Additionally, while patients who received the higher-dose steroid injection were less likely to need surgery than patients who received placebo, 73% of patients in the steroid group still required surgery within 1 year. A major limitation of the study is the exclusion of patients with any secondary causes of CTS, such as diabetes, thyroid disorders and inflammatory disease, which restricts the generalizability of the findings. Future studies might evaluate the effect of more frequent steroid injections on rates of surgery.
In-Depth [randomized, double-blind, placebo-controlled study]: This Swedish study randomized 111 CTS patients to receive either (1) one injection of 80 mg methylprednisolone, (2) one injection with 40 mg methylprednisolone or (3) placebo. Patient data, including symptom severity scores and rates of surgery, were analyzed at multiple time points for one year after the injection. All patients had the option to pursue surgery at any time during the study period. Authors analyzed CTS symptom severity scores at 10 weeks using mixed-model analysis of repeated measures, adjusting for baseline severity scores. Rates of surgery at 1 year after injection were then calculated using both logistic regressions and Cox regression analyses. Time to surgery was analyzed using Kaplan-Meier curves. Study investigators, personnel, and patients were blinded to treatment arm.
Of the 111 patients randomized, data was analyzed from 108 patients at 10 weeks and 111 patients at 1 year. Baseline characteristics, including symptom severity scores, were generally similar among groups. At 10 weeks, CTS symptom severity score improved significantly more in patients who received methylprednisolone than those who received placebo (mean difference in change from baseline was -0.64 on a 5-point scale, CI -1.06 to -0.21). However, there was no significant difference in symptom severity between high and low doses of methylprednisolone. At 1 year, patients who received the 80 mg steroid injection had a lower likelihood of having surgery (OR 0.42, CI 0.06-0.95) and a lower relative risk for surgery (0.79, CI 0.64-0.99) than patients in the placebo arm. Additionally, time from injection to surgery was longer for both the steroid groups than the placebo group. However, 73%, 81%, and 92% of patients in the 80-mg methylprednisolone, 40-mg methylprednisolone, and placebo groups, respectively, eventually required surgery within 1 year. Finally, pain after injection was reported by significantly more patients (n = 24) in each methylprednisolone group than in the placebo group (n = 6).
By Sarah Chuzi and Aimee Li, M.D.
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