Detecting median nerve strain changes with cyclic compression apparatus: a comparison of carpal tunnel syndrome patients and healthy controls.

The objective of this study was to detect differences in median nerve strain between patients with carpal tunnel syndrome and healthy controls using cyclic compression apparatus. Twenty-eight patients with idiopathic carpal tunnel syndrome and 30 normal patients were examined by ultrasound elastography. Median nerve strain, strain ratio of reference coupler and median nerve area and perimeter were measured. The areas under receiver operating characteristic curves were compared among the parameters. Median nerve strains of the patients were significantly smaller than those of the controls (p < 0.001). Strain ratios, areas and perimeters were significantly larger in the patients than in the controls (p < 0.001). The areas under curves were 0.963, 0.917, 0.759 and 0.706 for strain, strain ratio, area and perimeter, respectively. The median nerve strain had the highest area under the curve. The ultrasonic strain measurements of the median nerve provided by the cyclic compression apparatus were superior to morphologic assessment in diagnosing carpal tunnel syndrome.