Comparison of Ultrasonographic and Electrodiagnostic Findings Between Healthy and CTS Thais

Abstract

OBJECTIVE To compare the ultrasonography cross-sectional area (CSA) of the median nerve at the wrist (CSA-D), the wrist-to-forearm median nerve CSA ratio (WFR) and the difference (WFD) between individuals with carpal tunnel syndrome (CTS) and normal individuals in the Thai population and to explore the correlation between ultrasonography and electrodiagnosis (EDX). METHODS A cross-sectional study was performed on a total of 112 wrists of 72 participants who were divided into two groups. Fifty-six wrists of 36 EDX-confirmed CTS patients were recruited as the CTS group and an equal number of individuals without CTS were chosen as a control group. Participants were matched for demographic data from a historical study. For both individuals with clinical CTS confirmed by EDX and the control population median nerve CSA levels at the wrist and at mid-forearm were measured by ultrasonography. A comparison was made between the parameters of the study group and those of the control group. The correlations between the CSA-D, the WFR, and the WFD and the severity of CTS evaluated by EDX were studied. RESULTS The mean median nerve CSA-D, WFR, and WFD of the CTS patients were 14.7 ± 5.9 mm², 3.1 ± 1.4, and 9.7 ± 6.1 mm², respectively. In contrast, the mean median nerve CSA-D, WFR, and WFD of the control group were 9.6 ± 2.4 mm², 1.7 ± 0.4, and 3.8 ± 1.9 mm², respectively, indicating a statistically significant difference from the study group (p < 0.001). The optimal cut-point values for the median nerve CSA-D, WFR, and WFD in detecting CTS were 10.7 mm² (sensitivity 67.9%, specificity 83.9%), 1.8 (sensitivity 89.3%, specificity 71.4%), and 4.7 mm² (sensitivity 82.1%, specificity 81.8%), respectively. The median nerve CSA-D, WFR, and WFD exhibited significant moderate to strong positive correlation with the EDX grading of CTS severity. CONCLUSIONS Ultrasonography of the median nerve CSA-D, WFR, and WFD are efficient for distinguishing CTS patients from asymptomatic controls with good sensitivity and specificity in the Thai population. WFD demon-strated superiority in the areas of sensitivity, specificity, and accuracy.