Evaluation of Spastic Muscle in Stroke Survivors Using Magnetic Resonance Imaging and Resistance to Passive Motion

Generated torque in response to passive movement of spastic (affected side) and nonspastic (unaffected side) arm movements at varying velocities for the (A) elbow extensors and (B) flexors in 6 hemiplegic stroke survivors. *Affected greater than unaffected at respective velocity. ^†Affected extensors: 1.571>0.087 radians/s, affected flexors: 1.571>1.047>0.087 radians/s.

Variation in reflex torque with respect to subjective scoring based on the MAS. Note the more sensitive detection of spastic hypertonia (reflex torque) via mechanically detected force to passive movement in (A) the elbow extensors of subjects with varying degrees of MAS scores and the variation in reflex torque in (B) the elbow flexors despite all subjects having an MAS score of 1 or 1+.

(A) Muscle strength and (B) CSA of the affected and unaffected sides. *Unaffected greater than affected.

A representative example of an MRI scan of the unaffected and affected upper arm. Note the reduced muscle size in the elbow extensors and the increased signal intensity of the elbow flexors on the affected side.

MRI T2 values of spastic (affected) and nonspastic (unaffected) skeletal muscle at rest and after resistance exercise. *Significant increase from postexercise value. ^†Affected postexercise greater than unaffected postexercise.