Contribution of power Doppler and gray-scale ultrasound of the median nerve in evaluation of carpal tunnel syndrome

Abstract

To assess the role of gray-scale and power Doppler ultrasound (US) of the median nerve at the wrist in evaluating carpal tunnel syndrome (CTS). Seventy-one wrists in 51 patients with CTS in addition to 50 healthy volunteers that served as the control group were enrolled in this study. The following sonographic parameters were evaluated in both patients and controls: cross sectional area of the median nerve just proximal to the tunnel inlet (CSA1), at the pisiform bone level (CSA2), the CSA difference (ΔCSA), flattening ratio of the median nerve and bowing of the flexor retinaculum. The power Doppler US was used to assess the number of nerve vessels with estimation of the vascularity score. The ΔCSA revealed an excellent discriminative ability (AUC = 0.988) in differentiating patients with CTS at an optimal cut-off value of 3.9 mm2. Intraneural hypervascularization was significantly correlated with the ΔCSA of the median nerve (P < 0.001), while not significantly correlated with the age of patients, median nerve flattening ratio and bowing of flexor retinaculum. The ΔCSA and vascularity score of the median nerve are important and useful sonographic parameters in evaluation of CTS.