A prospective study of the long-term efficacy of local methyl prednisolone acetate injection in the management of mild carpal tunnel syndrome

Abstract

Objective. Local glucocorticoid injections are used to treat carpal tunnel syndrome (CTS). However, this treatment is associated with frequent relapses. An important limitation of studies with higher relapse rates is that no attempt has been made to identify patients with mild or severe disease. We evaluated the efficacy of local glucocorticoid injection in patients with mild CTS. Method. Mild CTS was defined as intermittent symptoms without absence of sensations, muscle atrophy or weakness of the thenar muscles. Forty-eight patients with idiopathic mild CTS were evaluated before and 3 and 12 months after a single local injection of 40 mg methyl prednisolone acetate. Outcome was assessed by overall satisfaction on a 100 mm visual analogue scale, the Boston self-administered questionnaire for symptom severity and functional scores and improvement in the electrophysiological parameters. Results. At 3 months, 93.7% of the patients reported marked improvement in their symptoms, with significant improvement in the mean values of the nerve conduction parameters distal motor latency at the wrist (DML) (P = 0.00001), distal sensory latency at mid-palm (DSL MP) (P = 0.014) and distal sensory latency at the wrist (DSL W) (P = 0.0003), and symptom severity (P = 4.96 × 10⁻⁸) and the functional scores (P = 3.56 × 10⁻⁵). Significant improvement was still present for DML (P = 1.39 × 10⁻⁵) at 12 months. Almost 50% of the patients achieved normalization in the electrophysiological study. At a median follow-up of 16 months, 79% patients continued to have improvement in their symptoms. Eight patients (16.6%) relapsed following the initial response. Conclusions. Local glucocorticoid injection results in long-term improvement in nerve conduction parameters, symptom severity and functional scores in patients with mild CTS.