The usefulness of ultrasonography in the diagnosis of carpal tunnel syndrome.

This study assessed the use of ultrasound in the diagnosis of carpal tunnel syndrome and to determine the best ultrasound criterion for diagnosis. Forty wrists of 27 patients with surgically proven moderate and severe carpal tunnel syndrome and 30 wrists of 15 controls were examined. Measurements of the cross-sectional area and the anteroposterior diameter of the median nerve at the inlet and outlet of the carpal tunnel were obtained. Patients also underwent electrophysiological evaluation. Median nerve ultrasonographic measurements were significantly higher in patients. The cross-sectional area of the median nerve at the tunnel inlet was found to be the most useful diagnostic criterion. The optimal cut-off value was 6.5 mm2 (sensitivity 89.5%, specificity 93%). Ultrasound parameters failed to correlate with the electrophysiological findings. The usefulness of ultrasonography in the diagnosis of carpal tunnel syndrome is discussed.