Comparing the Diagnostic Value of Ultrasonography with Electrodiagnostic Tests in Carpal Tunnel Syndrome

Abstract

Background: Median neuropathy due to nerve compression in the wrist, or carpal tunnel syndrome (CTS), is the most common entrapment neuropathy. Incidence of CTS is high at an estimated value of 280.6 per 100,000 patients per year. Accurate diagnosis of CTS is essential for treatment and preventing disability and morbidity. Methods: 64 patients with clinical diagnosis of CTS from the out-patient clinic of Alzahra Hospital, Isfahan, Iran were evaluated between January and March 2013. All the patients (54 women and 10 men) underwent nerve conduction study (NCS) and ultrasonography. The cross sectional area of the median nerve at the level of pisiform bone and 12cm proximal to that in elbow was estimated via ultrasonography which were used to calculate wrist/forearm ratio(WFR). The cut-off point value for WFR of median nerve was assessed and sensitivity and specificity of ultrasonography for CTS diagnosis was also determined. Findings: The optimal diagnostic cut-off values of CTS that we obtained by ROC curve was 2.07 and the areas under the ROC curve, was 0.8. This cut-off value had a sensitivity of 76%, specificity of 83%, positive predictive value (PPV) of 95% and negative predictive value (NPV) of 45%. Conclusion: The WFR is a new option in the ultra-sonographic diagnosis of CTS. This technique does not add significant time to routine ultra-sonographic examination .The use of a ratio also helps to omit the variability between populations and anatomic variation. Our initial findings suggest a high sensitivity for this method, but study of a larger population is needed for confirmation.

Keywords

• Carpal tunnel syndrome
• Ultrasonography
• Cross sectional area