Median nerve movement in the carpal tunnel before and after carpal tunnel release using transverse ultrasound

Purpose: We aimed to compare the movement of the median nerve within the carpal tunnel during wrist and finger motions between before and after carpal tunnel release (CTR) using transverse ultrasound in carpal tunnel syndrome (CTS) patients and to evaluate the biomechanical efficacy of CTR for CTS. Methods: Twenty-four patients with CTS were examined by transverse ultrasound. The location of the median nerve within the carpal tunnel was examined quantitatively as a coordinate at varied wrist positions with finger extension and flexion, respectively, before and after CTR. Results: We found that the median nerve moved statistically significantly more palmarly after CTR than before at all wrist positions during finger motion. The average median nerve displacement toward the palmar side at the palmar flexion position in finger flexion was the greatest among all positions. Additionally, the displacement amounts of the median nerve during finger motion at all wrist positions were statistically significantly smaller after CTR than before. Conclusions: The current study demonstrated the movement patterns of the median nerve in the carpal tunnel during wrist and finger motions compared before and after CTR using transverse ultrasound in CTS patients. The findings suggested that as the median nerve shifted greatly palmarly away from the tendons after CTR, the nerve avoids compression or shearing stress from the tendons. This ultrasound information could offer further understanding of the pathomechanics of CTS and provide a more accurate diagnosis of CTS and better treatment by CTR.