Evaluation of high-frequency ultrasonography for diagnosis of carpal tunnel syndrome.

The aim of this study was to assess the sensitivity and specificity of ultrasonography in the diagnosis of carpal tunnel syndrome. The cross-sectional area of the median nerve at the carpal tunnel for a positive diagnosis had a sensitivity of ∼ 98.6% but a specificity of 60%. The measure of the difference in cross-sectional area of the median nerve at the carpal tunnel and at the level of pronator quadratus had much better sensitivity and specificity of 97.1% and 80%, respectively. Signs of nerve flattening, palmar bowing and increased nerve vascularity were valuable in confirming the diagnosis. A positive predictive value of ultrasonography was found to be > 95% and a negative predictive value was ∼ 66% for a diagnosis of carpal tunnel syndrome. Ultrasonography is, therefore, an effective diagnostic tool in this regard.