Over the years NCS has been used to diagnose and monitor the patients with CTS though USG has several advantages as diagnostic tool. This study has been done to find out the diagnostic accuracy of USG in CTS and to compare the efficacy of USG with standard NCS in CTS.
Prospective cross-sectional analytical study was conducted at Dept. of PM&R, IPGME&R, Kolkata from 1st March, 2012 to 31st August 2012 (6 months). Patient with clinical diagnosis of CTS of age >18 year of both sexes were included in this study and on the other hand patient with previous wrist surgery /injury, wrist deformity, diabetes mellitus, anatomical variants of median nerve on ultrasound were excluded from the study.
After getting institutional ethical committee clearance, all patients who fulfil the above criteria were included in the study and further diagnostic conformation done by the standard diagnostic criteria of NCS. The same group of patients have been also screened by ultrasonography (USG).
At the end of the study, data analysis showed that sensitivity and specificity were 92.3 and 70.0% respectively. Predictive value of +test, predictive value of -test were 88.9 and 77.8% respectively. Kappa value was 0.64 (between 0.5 and 0.7). It signifies that there is good correlation between NCS and USG as diagnostic tool of CTS. The comparison of the numerical values of median latency, amplitude and CSA USG within the groups with the help of ANOVA followed by Tukey's test showed that there was good correlation between latency and amplitude in mild, moderate, severe and profound CTS but unfortunately it was not correlated with the CSA measured by USG.
USG can be used for screening large population of patients as it is simple, easily available, non-invasive test and has relatively low cost and useful in evaluating and excluding local causes of nerve compression.