Sonography of the Median Nerve in Carpal Tunnel Syndrome with Diabetic Neuropathy

Abstract

Objective: The aim of this study was to determine the criteria for ultrasonographic measurement of the cross-sectional area (CSA) of the median nerve and differential diagnosis of patients with carpal tunnel syndrome (CTS) with or without diabetic polyneuropathy (DPN). Design: One hundred eighty-seven patients were divided into five groups: healthy controls, CTS, diabetes with CTS but without DPN, DPN only, and both DPN and CTS. The CSAs of the median nerve were measured at four levels, and cutoff values to diagnose CTS with DPN were obtained. Results: All the CSAs were larger in the DPN group compared with those in the control group. The CSAs of the median nerve at the wrist revealed no significant differences among the groups with CTS; however, these groups demonstrated larger CSAs at the wrist and a higher wrist/forearm ratio compared with the DPN only group. The cutoff value for the CSA at the wrist that yielded the highest sensitivity and specificity was 11.6 mm. Conclusions: The CSA of the median nerve at the wrist and the wrist/forearm ratio could be useful for diagnosing the comorbidity of CTS with DPN.