Median nerve cross sectional area at the distal wrist and nerve conduction findings in patients with carpal tunnel syndrome: A comparative study

Carpal tunnel syndrome (CTS) is the most common form of peripheral entrapment neuropathy. Ultrasound (US) has emerged as a valuable diagnostic tool for musculoskeletal conditions, including CTS. The aim of the present study was to evaluate the correlation between the cross‑sectional area of the median nerve (MN) at the distal wrist (CSA‑D) with the severity of CTS, as determined by nerve conduction studies (NCS). For this purpose, a total of 60 female patients with clinical CTS symptoms underwent ultrasound CSA‑D measurements at the carpal tunnel inlet, followed by NCS by a blinded electrophysiologist to the US findings. The results revealed that CSA‑D exhibited a significant positive correlation with MN distal motor latency (R=0.588, P<0.001) and sensory latency (R=0.541, P<0.001). Conversely, a significant negative correlation was observed with motor conduction velocity (R=‑0.373, P=0.003), sensory action potential amplitude (R=‑0.592, P<0.001) and sensory conduction velocity (R=‑0.562, P<0.001). In discriminating mild vs. severe CTS, US had an area under the receiver operating characteristic (ROC) curve (AUC) value of 0.910 (95% CI, 0.826‑0.994, P<0.001), with 95% sensitivity and 86% specificity at CSA‑D=17.5 mm2. On the whole, CSA‑D correlates significantly with NCS parameters in CTS. US is more effective in differentiating mild from severe CTS, than mild from moderate CTS. US is a highly effective modality for distinguishing between mild and severe CTS, demonstrating superior diagnostic performance for this specific differentiation compared to distinguishing mild from moderate disease.