Sonography versus nerve conduction studies in patients referred with a clinical diagnosis of carpal tunnel syndrome

Purpose. To compare the diagnostic value of high-resolution ultrasound (US) with nerve conduction studies (NCS) in patients with clinically defined carpal tunnel syndrome (CTS). Methods. A prospective study was conducted on 66 consecutive patients investigated for sensory hand symptoms. The gold standard was the clinical diagnosis of CTS. Results. NCS showed greater diagnostic sensitivity (82%) than US (62%) in supporting a diagnosis of CTS. With increasing neurophysiologic severity of median neuropathy, there was increasing convergence of the two test methods. Abnormal US as the only diagnostic supportive evidence of CTS was rare. However, the positive predictive value of US for CTS was 100%. Conclusion. NCS show better sensitivity than US in supporting a diagnosis of CTS. However, because of its high positive predictive value, one may consider using US as a screening test, eliminating the need for NCS in the majority of clinical suspicion of CTS and reserving NCS for cases in which US is negative.