Andrea Klauser MD, Presenter: Nothing to Disclose

Ethan Joseph Halpern MD, Abstract Co-Author: Grant, Bristol-Myers Squibb Company Equipment support, Toshiba Corporation

Tobias De Zordo MD, Abstract Co-Author: Nothing to Disclose

Carlo Martinoli MD, Abstract Co-Author: Nothing to Disclose

Gudrun Feuchtner MD, Abstract Co-Author: Nothing to Disclose

Werner R. Jaschke MD, PhD, Abstract Co-Author: Nothing to Disclose

To improve the accuracy of the diagnosis of carpal tunnel syndrome (CTS) by comparing cross-sectional-area (CSA) measurements of the median nerve obtained at the level of the carpal tunnel (CSAc) to those obtained more proximally (CSAp), at the level of the pronator quadratus muscle.

Study protocol was approved by the university ethics committee and written consent was obtained. One hundred wrists in 68 consecutive patients with CTS (16 men, 52 women; mean age, 57.9 years; range 25–85 years) and 93 wrists in 58 healthy volunteers (16 men, 42 women; mean age, 55.1 years, range, 17-85 years) were examined by ultrasound (US). Electrodiagnostic tests confirmed the diagnosis of CTS in all 68 patients. The US examiner was blinded to these test results. Median nerve CSA was measured at two levels and a ΔCSA, corresponding to the difference between CSAc and CSAp was calculated for each wrist.

In healthy volunteers mean CSAc (9.0 mm²) was lower than mean CSAc in patients (16.8 mm²; P < .01). ΔCSA was smaller in normal wrists (0.25 mm²) when compared with CTS patients (7.4 mm²; P < .01). ROC analysis demonstrates a diagnostic advantage to the use of ΔCSA parameter as compared with CSAc (P = 0.036). Optimal diagnostic discrimination is obtained with a ΔCSA threshold of 2 mm², resulting in a sensitivity of 99% and specificity of 100%.

The use of a ΔCSA parameter improves the diagnostic accuracy of US for the presence of CTS.

The use of a ΔCSA parameter improves the significance of US in the diagnostic algorithm of CTS.

Klauser, A, Halpern, E, De Zordo, T, Martinoli, C, Feuchtner, G, Jaschke, W, Carpal Tunnel Syndrome Assessment by US: Value of an Additional Cross Sectional Area Measurement of the Median Nerve in Patients Compared to Healthy Volunteers.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6016941.html