RESUMO
OBJECTIVE: To investigate the diagnostic value of cross-sectional area (CSA) and wrist to forearm ratio (WFR) in patients with electro-diagnosed carpal tunnel syndrome (CTS) with or without diabetes mellitus (DM). METHODS: We retrospectively studied 256 CTS wrists and 77 healthy wrists in a single center between January 1, 2008 and January 1, 2013. The CSA and WFR were calculated for each wrist. Patients were classified into four groups according to the presence of DM and CTS: group 1, non-DM and non-CTS patients; group 2, non-DM and CTS patients; group 3, DM and non-CTS patients; and group 4, DM and CTS patients. To determine the optimal cut-off value, receiver operating characteristic (ROC) curve analysis was performed. RESULTS: The CSA and WFR were significantly different among the groups (p<0.001). The ROC curve analysis of non-DM patients revealed CSA ≥10.0 mm2 and WFR ≥1.52 as the most powerful diagnostic values of CTS. The ROC curve analysis revealed CSA ≥12.5 mm2 and WFR ≥1.87 as the most powerful diagnostic values of CTS. CONCLUSION: Ultrasonographic assessment for the diagnosis of CTS requires a particular cut-off value for diabetic patients. Based on the ROC analysis results, improved accurate diagnosis is possible if WFR can be applied regardless of presence or absence of DM.