Objective quantification of spastic hypertonia: correlation with clinical findings.

To develop a reliable and objective technique for quantifying spastic hypertonia, ten chronically hemiplegic patients with varying degrees of spasticity were studied on three occasions during several weeks. The modified Ashworth scale, a clinical assessment of extremity tone, was performed before and after each of the following objective tests: (1) torque and EMG measurements during ramp and hold angular displacement about the elbow, (2) pendulum test of the lower extremity, and (3) H/M ratio studies of upper and lower extremities. Subject motor function was also quantified using the Fugl-Meyer motor assessment scale. A regression analysis was performed to determine how successfully each of the objective measures correlated with the clinical yardstick, the modified Ashworth scale. A similar correlation between the objective measures and the Fugl-Meyer motor assessment scale was performed. Temporal reproducibility of a test for a given subject was evaluated by performing an ANOVA of repeated measures for each test over the three study sessions in a given subject. We conclude that (1) both the ramp and hold threshold measurements and pendulum test offer acceptable objective measures of spastic hypertonia since they correlate closely with clinical perception, (2) the Fugl-Meyer motor assessment scale also correlates closely with the severity of spastic tone, and (3) objective measures of spastic hypertonia are often surprisingly reproducible when repeatedly applied to a selected group of chronic hemiplegic patients with long-standing spasticity.