Relationship Between Electrodiagnosis and Various Ultrasonographic Findings for Diagnosis of Carpal Tunnel Syndrome

OBJECTIVE To investigate the relationship between electrodiagnosis and various ultrasonographic findings of carpal tunnel syndrome (CTS) and propose the ultrasonographic standard that has closest consistency with the electrodiagnosis. METHODS Ultrasonography was performed on 50 female patients (65 cases) previously diagnosed with CTS and 20 normal female volunteers (40 cases). Ultrasonography parameters were as follows: cross-sectional area (CSA) and flattening ratio (FR) of the median nerve at the levels of hamate bone, pisiform bone, and lunate bone; anteroposterior diameter (AP diameter) of the median nerve in the carpal tunnel; wrist to forearm ratio (WFR) of median nerve area at the distal wrist crease and 12 cm proximal to distal wrist crease; and compression ratio (CR) of the median nerve. Independent t-test was performed to compare the ultrasonographic findings between patient and control groups. Significant ultrasonographic findings were compared with the electrodiagnosis results and a kappa coefficient was used to determine the correlation. RESULTS CSA and FR of median nerve at the hamate bone level, CSA of median nerve at pisiform bone level, AP diameter of median nerve within the carpal tunnel, CSA of median nerve at the distal wrist crease and WFR showed significant differences between patient and control groups. WFR showed highest concordance with electrodiagnosis (κ=0.71, p<0.001). CONCLUSION These findings suggested the applicability of ultrasonography, especially WFR, as a useful adjunctive tool for diagnosis of CTS.