Role of High Frequency Ultrasound in Diagnosing Carpal Tunnel Syndrome as Compared with Conventional Nerve Conduction Studies

OBJECTIVE: Our aim was to evaluate High Frequency Ultrasonography as a tool for diagnosis in patients withcarpal tunnel syndrome in comparison with electrophysiological study. METHODS: Thirty- one patients [56 hands] with CTS and twenty-five asymptomatic controls [50 hands] were assessed and underwent ultrasonography of the wrists and electrophysiological testing. Data from the patient and the control groups was compared for both the investigations to determine the CTS and the grade of severity. RESULTS: There was a high degree of correlation between the conduction abnormalities of the median nerve as detected by electrodiagnostic tests, historic and objective scale [Hi-Ob] and the measurement of the cross-sectional area of the nerve by US (P < 0.05). A cut-off point of 0.88 mm(2) for the mean cross-sectional area of the median nerve was found to be the upper limit for normal values. Compared to Ultrasonography which found one hand negative, six hands (10%) were negative on the electrophysiological tests. Using critical CSA value of 1.0 mm(2) in these CTS cases by US with sensitivity and specificity of 100% and 88%. Based on the results of this study, ultrasonography of wrist is another useful tool along with nerve conduction studies as per sensitivity and specificity patterns found in our study in diagnosis of carpal tunnel syndrome. CONCLUSION: High-frequency US examination of the median nerve and measurement of its cross-sectional area can be strongly considered as useful diagnostic diagnostic modality for the evaluation of CTS along with nerve conduction studies. In addition to its high diagnostic accuracy it is able to define the cause of nerve compression, aids treatment planning and provides a reliable method to follow response to therapy.