Correlations of Median Nerve Area,Strain,and Nerve Conduction in Carpal Tunnel Syndrome Patients

Abstract

Background: The objective of this study was to see if ultrasound-interpreted median nerve strain and cross-sectional area correlate with abnormal nerve conduction studies and thumb opposition strength in patients with carpal tunnel syndrome (CTS). Methods: Sixty wrists of 30 idiopathic CTS patients were assessed by ultrasound and nerve conduction study. Distal motor latency, cross-sectional area, and strain ratio of the median nerve were measured. In addition, thumb opposition strength was classified using the manual muscle testing grade from 0 to 5, clinically. The strain ratio was defined as the strain of the reference coupler divided by the strain of the median nerve. The correlations between clinical examinations of distal motor latency, cross-sectional area, strain ratio, and thumb opposition strength were estimated with the Spearman rank correlation coefficients. Results: The correlation coefficients between distal motor latency and strain ratio, distal motor latency and cross-sectional area, and strain ratio and cross-sectional area were .597, .352, and .324, respectively. The correlation coefficients between thumb opposition strength and distal motor latency, thumb opposition and cross-sectional area, and thumb opposition and strain ratio were −.523, −.307, and −.358, respectively. All of the correlations showed statistical significance. The correlation coefficients between distal motor latency and strain ratio, and thumb opposition and distal motor latency, were relatively high. Conclusions: The results of this study suggest that the nerve conduction delay is related to changes in the material properties of the median nerve. In addition, nerve conduction study was the principal indicator of the thumb opposition strength.