ABSTRACT
Objective:To measure the change in Young′s modulus of the biceps brachii during passive stretching and to assess the potential of shear wave elastography (SWE) as an auxiliary quantitative technique for assessing muscle tone.Methods:Forty-nine stroke survivors and 30 healthy subjects were evaluated using the modified Ashworth scale (MAS). According to their MAS scores they were divided into a healthy group, a healthy elbow group, an MAS class-0 group, an MAS class-1 group, an MAS class-1 + group and an MAS class-2 group. During passive extension of the subjects′ elbows, shear wave elastography was used to image the biceps brachii. Six points of the elbow were selected to record the instantaneous Young′s modulus ( EX) and calculate its change during the movement (Δ E). Those data were correlated with the MAS scores and compared among the groups. Results:Persons with higher MAS scores tended to have a higher Young′s modulus of the biceps brachii, and the modulus was likely to increase more with increases in the angle of elbow extension. From half of the range of motion to full extension there were significant differences in EX and Δ E between MAS class-0 and class-1 groups, as well as between the class-0 and class-1 + groups. There were, however, no significant differences between MAS class-1 and MAS class-1 + . Conclusions:MAS scores can usefully predict biceps brachii stiffness during passive elbow flexion. Shear wave elastography can quantify that stiffness and also muscle tone.