Sonography versus Nerve Conduction Studies in Patients Referred with a Clinical Diagnosis of Carpal Tunnel Syndrome

D. Pastare, MD, A.K. Therimadasamy, BSc, E. Lee, E.P. Wilder-Smith, MDNeurology, National University Health Systems, 5 Lower Kent Ridge Road, 119074, SingaporeReceived 1 October 2008; accepted 20 April 2009ABSTRACT: Purpose. To compare the diagnosticvalue of high-resolution ultrasound (US) with nerveconduction studies (NCS) in patients with clinicallydefined carpal tunnel syndrome (CTS).Methods. A prospective study was conducted on 66consecutive patients investigated for sensory handsymptoms. The gold standard was the clinical diag-nosis of CTS.Results. NCS showed greater diagnostic sensitivity(82%) than US (62%) in supporting a diagnosis ofCTS. With increasing neurophysiologic severity ofmedian neuropathy, there was increasing conver-gence of the two test methods. Abnormal US as theonly diagnostic supportive evidence of CTS was rare.However, the positive predictive value of US for CTSwas 100%.Conclusion. NCS show better sensitivity than US insupporting a diagnosis of CTS. However, because ofits high positive predictive value, one may considerusing US as a screening test, eliminating the need forNCS in the majority of clinical suspicion of CTS andreserving NCS for cases in which US is neg-ative.