Peripheral nerve ultrasonography in association with ENMG, with special reference to carpal tunnel syndrome

BACKGROUND Peripheral nerve ultrasonography (US) is a rather new method in assessment of peripheral neuropathies when performed in combination with electroneuromyography (ENMG). US can be used to identify the location of nerve damage and to detect possible structural pathology of adjacent tissue.

METHODS The material was gathered from US and ENMG examination reports from the Department of Clinical Neurophysiology of Tampere University Hospital covering a period of nine months. Variables gathered from the reports included all nerves examined with US and, in the case of carpal tunnel syndrome (CTS), also median nerve cross-sectional area (CSA) assessed by US and severity of CTS assessed by ENMG.

RESULTS Ultrasonography was performed on 660 peripheral nerves of 383 patients. A positive correlation was found between the severity of CTS and median nerve CSA (r = 0.412, p < 0.001), although CSA alone could not predict the severity of CTS.

CONCLUSIONS The use of US in combination with ENMG is increasing in the workup of peripheral neuropathies. When examining for possible CTS, US can be used to complement ENMG and provide additional anatomical information, but it cannot replace it as a diagnostic tool.