Accuracy of high-resolution ultrasonography in establishing the diagnosis of carpal tunnel syndrome.

Abstract

The aim of this study was to evaluate the accuracy of high-resolution ultrasonography in the diagnosis of carpal tunnel syndrome (CTS). It included 50 patients with signs and symptoms suggestive of CTS and 50 individuals as control group. Cross-sectional area of median nerve at the inlet of carpal tunnel was measured in control as well as symptomatic group by ultrasonography. In addition, nerve conduction studies (NCS) were carried out in the symptomatic group. Radiologists performing the ultrasonography were blinded to the results of NCS. Sensitivity, specificity and accuracy of ultrasonography and NCS in the diagnosis of CTS were calculated and compared. In control group, cross-sectional area of the median nerve ranged between 5 and 7.3 mm2 , whereas in the symptomatic group it varied from 8.4 to 16.5 mm2 . It was >9 mm2 in 47 patients. With a cut-off of 9 mm2 , sensitivity, specificity and accuracy of ultrasonography in diagnosing CTS were 95%, 100% and 97%, respectively. NCS was diagnostic of CTS in 48 (96%) patients. Ultrasonographic examination gives similar results to NCS in establishing diagnosis of CTS and can be used as a screening modality with further use of NCS in cases where ultrasonography is non-diagnostic.