Diagnostic Value of Ultrasound Compared to Electro Diagnosis in Carpal Tunnel Syndrome

Carpal Tunnel Syndrome (CTS) is one of the main causes of disability. The diagnosis of CTS confirm by electrodiagnostic tests. Sonography is an alternative method for diagnosis of CTS that can investigate anatomy and probable pathology. The aim of this study is to investigate the multiple sonographic diagnostic criteria and compare its diagnostic value with electrodiagnosis. In this descriptive-cross sectional study, 84 wrists (42 patients with CTS and 42 individuals without any clinical signs in upper limb) were investigated. Symptomatic patients underwent clinical examination, standard electrodiagnostic evaluation of upper limb and sonographic investigation of median nerve in forearm and wrist. The control group underwent sonographic investigation. Cross Sectional Area (CSA) of Median nerve at distal wrist crease, at the level of Hamate hook and Trapezium, the amount of flexor retinaculum bowing, ratio of CSA at the forearm to distal wrist crease and ratio of CSA at the Pisiform level to distal wrist crease had significant difference in the case group compared to the control group (P-value<0.05). Among these criterion, the most sensitivity, NPV and accuracy was for CSA at distal wrist crease (73.8%, 72.5%, 71.4% respectively), the most specificity, PPV was at the level of Hamate hook and Trapezium (85.3%, 80% respectively). Our study reveals that sonography is a somehow sensitive and specific method in diagnosis of CTS and can be used as an adjuvant method in diagnosis of CTS but cannot substitute electrodiagnosis.