Is Ultrasound-Guided Steroid Injection Less Effective in Carpal Tunnel Syndrome Patients with Bifid Median Nerve?: A Focus on Short-Term Efficacy.

Abstract

Objective: To evaluate the impact of bifid median nerve (BMN) on treatment response to ultrasound-guided corticosteroid injection in patients with carpal tunnel syndrome (CTS).

Design: This observational study included 50 patients with mild to moderate CTS undergoing ultrasound-guided corticosteroid injection. During the procedure, 25 patients with a BMN and 25 with a normal median nerve (NMN) were consecutively selected. 21 from each group completed the 4-week follow-up. Symptom severity, functional status, and disability were assessed using the Visual Analog Scale (VAS), the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ), and the Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire (Quick-DASH). Treatment response was defined as a ≥ 50% reduction in VAS at 4 weeks post-injection.

Results: Pre-treatment VAS, BCTQ-SSS, BCTQ-FSS, and Quick-DASH scores did not differ between groups (p > 0.05). At 4 weeks, 76.19% of NMN patients achieved a ≥ 50% VAS reduction versus 33.33% in the BMN group (p = 0.005). While both groups improved post-injection (p < 0.05), the BMN group showed significantly lower improvement in VAS (p = 0.004), BCTQ-SSS (p = 0.015), BCTQ-FSS (p = 0.008), and Quick-DASH (p = 0.013).

Conclusions: Ultrasound-guided corticosteroid injection was effective in both groups, but response was significantly lower in BMN patients. BMN may be a risk factor for treatment failure, highlighting the need for alternative injection strategies or combination therapies to optimize outcomes.