Multilevel evaluation of the median nerve in carpal tunnel syndrome using microvascular doppler ultrasonography.

Abstract

To compare the diagnostic performance of microvascular ultrasonography-derived vascularity index (VI) and median nerve cross-sectional area (CSA) measured at multiple anatomical levels in relation to electroneuromyography (ENMG)-based severity of carpal tunnel syndrome (CTS). In this prospective study, 101 hands from 67 patients with ENMG-confirmed CTS (mild, moderate, severe) were evaluated. CSA was measured at four anatomical levels, and VI was obtained at three levels using a standardized microvascular ultrasonography protocol. Group differences were analyzed with non-parametric tests. Receiver operating characteristic (ROC) analyses were performed to assess diagnostic performance. CSA differed significantly across severity groups only at the pre-carpal tunnel level (P = 0.009). VI showed significant overall differences at the pre-carpal, proximal tunnel, and distal tunnel levels (P < 0.001, P < 0.001, and P = 0.001, respectively). For distinguishing moderate-to-severe CTS from mild CTS, pre-carpal and proximal tunnel VI measurements showed comparable discriminatory performance, with an AUC of 0.75 at both levels. For identifying severe CTS, pre-carpal tunnel VI showed an AUC of 0.76. VI derived from microvascular ultrasonography demonstrates a more consistent and discriminative association with CTS severity than CSA. These findings support its potential as a quantitative, non-invasive imaging biomarker for CTS severity stratification in clinical practice.