ULTRASONOGRAPHIC EVALUATION OF THE ABDUCTOR POLLICIS BREVIS MUSCLE IN PATIENTS WITH CARPAL TUNNEL SYNDROME CLASSIFIED ACCORDING TO EMG FINDINGS

İlhami ATA, Muhsin DORAN, Burcu HAZER, Kadriye ÖNEŞ

Cam and Sakura Medical Journal - 2026;6(1):9-17

University of Health Sciences Türkiye, İstanbul Physical Medicine and Rehabilitation Training and Research Hospital, İstanbul, Türkiye

 

Objective: To evaluate the relationship between quantitative muscle ultrasound parameters of the abductor pollicis brevis (APB) and disease severity in carpal tunnel syndrome (CTS). Material and Methods: This cross-sectional, comparative clinical study included 76 patients. Participants were stratified into four electromyography (EMG)-based categories (EMG-normal, mild, moderate, and severe CTS). In the transverse ultrasound images of the APB, we measured cross sectional area and thickness of the muscle. Differences in muscle thickness, cross-sectional area (CSA), and pinch strength among four groups were analyzed. Results: The CSA of the APB muscle decreases with increasing disease severity. Thickness and pinch strength are significantly decreased in severe CTS. There is a significant negative correlation between the CSA of the APB muscle and the distal motor latency of the median nerve. Conclusion: Quantitative ultrasound parameters of the APB muscle are useful for evaluating disease severity in CTS.