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

Abstract

The aim of the study was to evaluate the impact of bifid median nerve on treatment response to ultrasound-guided corticosteroid injection in patients with carpal tunnel syndrome. This observational study included 50 patients with mild to moderate carpal tunnel syndrome undergoing ultrasound-guided corticosteroid injection. During the procedure, 25 patients with a bifid median nerve and 25 with a normal median nerve were consecutively selected. Twenty-one from each group completed the 4-wk follow-up. Symptom severity, functional status, and disability were assessed using the visual analog scale, the Boston Carpal Tunnel Syndrome Questionnaire, and the Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire). Treatment response was defined as a ≥ 50% reduction in visual analog scale at 4 wks after injection. Pretreatment visual analog scale, Boston Carpal Tunnel Syndrome Questionnaire-Symptom Severity Scale, Boston Carpal Tunnel Syndrome Questionnaire-Functional Status Scale, and Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire scores did not differ between groups ( P > 0.05). At 4 wks, 76.19% of normal median nerve patients achieved a ≥ 50% visual analog scale reduction versus 33.33% in the bifid median nerve group ( P = 0.005). While both groups improved after injection ( P < 0.05), the bifid median nerve group showed significantly lower improvement in visual analog scale ( P = 0.004), Boston Carpal Tunnel Syndrome Questionnaire-Symptom Severity Scale ( P = 0.015), Boston Carpal Tunnel Syndrome Questionnaire-Functional Status Scale ( P = 0.008), and Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire ( P = 0.013). Ultrasound-guided corticosteroid injection was effective in both groups, but response was significantly lower in bifid median nerve patients. Bifid median nerve may be a risk factor for treatment failure, highlighting the need for alternative injection strategies or combination therapies to optimize outcomes.