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 correlated with 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.

Fig. 1

Representative ultrasound images of spastic muscles of the upper limb (FCU: flexor carpi ulnaris; BB: biceps brachii). Each muscle pair corresponds to the affected (A) and unaffected (U) sides of the same subject. Images from 2 different subjects are shown. The length of the white arrows represents muscle thickness. Modified Heckmatt scale shows increased echogenicity in affected spastic muscles.

Fig. 2

Representative ultrasound images of spastic muscles of the lower limb (RF: rectus femoris; MG: medial gastrocnemius). Each muscle image pair corresponds to the affected (A) and unaffected (U) sides of the same subject. Images from 2 different subjects are shown. The length of the white arrows represents muscle thickness. Modified Heckmatt scale shows increased echogenicity in affected spastic muscles.

Fig. 3

(A) Percentage decrease in muscle thickness of the affected side with reference to the unaffected side in muscles of the upper and lower limb (BB: biceps brachii; FCU: flexor carpi ulnaris; RF: rectus femoris; MG: medial gastrocnemius). No significant difference in reduction in muscle thickness was seen between muscles of the same limb. A significantly greater decrease in muscle thickness was observed in upper limb compared with lower limb muscles (p < 0.001). (B) Box and whisker plot of modified Heckmatt scale of muscles on the affected side. The modified Heckmatt scale score was significantly lower in the RF than in other muscles (p < 0.001). *Statistically significant difference.