Ultrasonography versus electrodiagnosis of median nerve before and after open carpal tunnel release surgery: which can better diagnose, predict and assess postoperative improvement?

Diagnosis of Carpal Tunnel Syndrome (CTS) relies on a structured clinical approach with Electrodiagnostic Studies (EDX) accepted as the gold standard in the diagnosis. Yet, Ultrasound (US) has emerged as a non-invasive alternative especially in assessing morphological changes. And so, to accurately diagnose CTS by a valid non-painful simple tool, objectively assess postoperative improvement and finally to predict postoperative clinical outcome from preoperative data; clinical, EDX, and US data were collected, compared and correlated pre- and 1 month postoperative. While US achieved diagnostic accuracy of 80% in CTS diagnosis, particularly Wrist Cross-Sectional Area (wCSA) and Wrist-Forearm Ratio (WFR), it remains less sensitive than EDX. The diagnosis of CTS using wCSA/WFR achieved a sensitivity of 80.0%/80.0% and a specificity of 100%/85.7%, at a cutoff score of 12.5mm2/2.1 or above. In addition, linear regression analysis showed that only compound motor action potential (CMAP) amplitude could predict postoperative clinical improvement. Sensitivity of EDX (93.33%) overcome that of the US in detection of postoperative improvement. US is less sensitive than EDX in diagnosing CTS, assessment and prediction of postoperative clinical outcome.