Diagnostic Value of Ultrasound in CTS in Diabetic Versus Nondiabetic Populations

PURPOSE: Diabetes mellitus (DM) is a well-known risk factor for carpal tunnel syndrome (CTS). However, few studies have compared differences in the cross-sectional area (CSA) of the median nerve in patients with and without DM. The purpose of this study was to compare the utility of ultrasound for the diagnosis of CTS in diabetic versus nondiabetic patients. METHOD: A total of 248 hands of 155 patients were evaluated: 154 hands belonged to non-DM patients with CTS, 80 to DM patients with CTS, 13 patients with DM but no CTS, and 51 patients without DM or CTS. All hands underwent ultrasonography of the median nerve at the wrist for determination of CSA; patients completed a CTS Symptom Severity Scale and Functional Status Scale for each hand. RESULTS: Average CSA (mm(2)) of non-DM patients with CTS was 11.25 whereas the average in DM patients with CTS was 12.23 (P = .17). Cross-sectional area of 9.5 or greater was the most powerful predictor of CTS in patients without DM, and CSA of 10.5 or greater in patients with DM. CONCLUSIONS: Cross-sectional area of the median nerve was similar for patients with and without DM; however, cutoff values for positive diagnosis may need to be adjusted in patients with DM. Ultrasonography of the wrist is a valuable resource for diagnosing CTS in patients with and without DM. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.