Is Palmar Cutaneous Branch of the Median Nerve More Swollen in Carpal Tunnel Syndrome?

OBJECTIVE: To investigate the characteristics of the palmar cutaneous branch of the median nerve (PCBMN) in patient with carpal tunnel syndrome (CTS) using high-resolution ultrasound. METHODS: Fourteen healthy volunteers (17 wrists) and 31 patients with CTS (41 wrists) were evaluated by high-resolution ultrasound. All patients were classified into three groups based on the electrophysiologic CTS impairment severity: mild, moderate, and severe. Using high-resolution ultrasound, the cross-sectional areas (CSAs) of the PCBMN were measured at the proximal wrist crease, bistyloid line, and distal wrist crease, and the largest CSA was defined as the maximal CSA. RESULTS: The maximal CSA of the PCBMN of the control, mild, moderate, and severe CTS groups were 0.27±0.08, 0.30±0.07, 0.35±0.10, and 0.47±0.13 mm(2), respectively. The maximal CSA of the PCBMN was significantly larger in the severe CTS group than in the other groups. CONCLUSION: The PCBMN could be concomitantly affected in patients with severe CTS.