Ultrasonography for the Diagnosis of Carpal Tunnel Syndrome in Diabetic Patients: Missing the Mark?

Purpose Diabetes mellitus (DM) and carpal tunnel syndrome (CTS) are common pathologies. The diagnosis of CTS can be facilitated by the use of an ultrasound-based wrist-to-forearm ratio (WFR) of the nerve diameter. However, the applicability of WFR in DM-patients is not yet clear. Materials and Methods 233 wrists of 153 patients were examined. Cross-sectional areas (CSA) of the median nerve were obtained using a linear array probe. The WFR was calculated. Results Diabetics with CTS had significantly lower WFR values than non-diabetics with CTS (p = 0.002). There was no difference between the WFR of diabetics with and without CTS (p = 0.06). The diagnostic accuracy between diabetics with and without CTS was low for measurements of WFR (ROC AUC = 0.630, 95 % CI 0.541 - 0.715, p = 0.011). Conclusion Our findings suggest that the WFR has a low diagnostic accuracy in diabetic patients with CTS and should be used with caution in those patients.