Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy. Different populations have different cross-sectional area (CSA) cut-offs for carpal tunnel syndrome. This study aimed to evaluate median nerve ultrasound in Egyptian CTS patients and matched controls, correlate ultrasound with nerve conduction studies, and determine optimal CSA cut-off at the inlet for CTS screening.

This study included 35 patients with CTS and 35 age and sex-matched healthy control. The median nerve conduction studies (NCS) and the median nerve CSA using ultrasound (US) at different locations, including the carpal tunnel inlet, were measured in all participants. The receiver operator characteristic (ROC) curve analysis was performed to detect the sensitivity and specificity of nerve US-measured CSA for diagnosis of CTS.

There was a significant difference in the median nerve CSA at the inlet and outlet between the CTS and control group. A significant correlation was found between the inlet and outlet CSA and the cMAP of the median nerve. The optimal cut-off CSA of the median nerve for anticipation of compression is≥ 8.8 mm2 at the inlet and ≥ 8.4 mm2 at the outlet.

Ultrasound can be used as a screening tool for diagnosing CTS by measuring the median nerve CSA. This study proposed cut-off values for median nerve CSA at the inlet and outlet cut-off values of ≥8.8 mm2 and ≥8.4 mm2, respectively. Further research with larger sample sizes and a unified US protocol is warranted to confirm the current findings.