Ultrasound Assessment of Spastic Muscles in Ambulatory Chronic Stroke Survivors Reveals Function-Dependent Changes

Abstract

Objective: To correlate ultrasound characteristics of spastic muscles with clinical and functional measurements in chronic stroke survivors.Methods: Ultrasound assessment and clinical and functional assessments were performed in 28 ambulatory stroke survivors (12 females, mean age 57.8 ± 11.8 years, 76 ± 45 months after stroke).Results: Muscle thickness in the affected side was decreased compared with the contralateral side (p < 0.001). The decrease was more evident in the upper limb muscles. On the affected side, the modified Heckmatt scale score was lowest (closer to normal) in the rectus femoris (RF) muscle compared with other muscles (biceps brachii (BB), flexor carpi ulnaris (FCU) and medial gastrocnemius (MG)). Muscle thickness and echogenicity of spastic muscles did not correlate with spasticity, as measured with the modified Ashworth scale (MAS), Fugl-Meyer motor assessment scores, age, or time since stroke. There was a significant negative correlation between grip strength and percentage decrease in muscle thickness for the spastic FCU muscle (r = –0.49, p = 0.008). RF muscle thickness correlatedwith ambulatory function (Timed Up and Go test (r = 0.44, p = 0.021) and 6-metre walk test (r = 0.41, p = 0.032)). There was no significant correlation between echogenicity and functional assessments Conclusion: Ambulatory chronic stroke survivors had function-dependent changes in muscle thickness on the affected side. Muscle thickness and echogenicity of spastic muscles did not correlate with spasticity, Fugl-Meyer motor assessment scores, age, or time since stroke. LAY ABSTRACTMuscle changes occur secondary to various factors after stroke. In this study, ultrasound characteristics of spastic muscles and clinical and functional assessment were performed in 28 ambulatory chronic stroke survivors. Muscle thickness in the affected side was decreased compared with the contralateral side. The decrease was more evident in the upper limb muscles. The percentage decrease in the flexor carpi ulnaris muscle thickness correlated negatively with grip strength, while the rectus femoris muscle thickness correlated with ambulatory function. Echogenicity was lowest in the rectus femoris compared with other muscles. Muscle thickness and echogenicity of spastic muscles did not correlate with spasticity, Fugl-Meyer motor assessment scores, age, or time since stroke. These function-dependent changes in muscles on the affected side suggest an important role of voluntary muscle activation in preserving muscle mass after stroke. Stroke motor rehabilitation programmes should focus on active use of muscles on the affected side for strengthening and preserving muscle mass.