Ultrasound Assessment of Muscle and Fascia Properties and the Effects of Spasticity and Botulinum Toxin Injections on Spastic Muscles in Chronic Stroke Survivors.

[OBJECTIVE] The aim of the study was to objectively quantify changes in muscle properties in chronic stroke survivors and the effects of spasticity and botulinum toxin injections on muscle properties using ultrasonography.

[DESIGN] In this cross-sectional observational study, 24 stroke subjects with history of botulinum toxin injections to biceps brachii muscles but without botulinum toxin injections to the triceps were included.

[RESULTS] Twelve subjects had spastic triceps, and the other half did not. Twenty subjects had spasticity in wrist flexors, and 11 subjects received botulinum toxin injections to the flexor carpii ulnaris. On average, a significant decrease in muscle thickness (16.5% loss in triceps), a thicker fascia with higher echo intensity was noted on muscles in the paretic limb. Percent muscle loss was significantly less (11.0%) in spastic triceps than in nonspastic triceps (22.1%). There was no statistically significant difference in muscle and fascia properties in spastic flexor carpii ulnaris with and without botulinum toxin injection. Spasticity did not correlate significantly with muscle loss, fascia thickness, or echo intensity.

[CONCLUSIONS] Our results provided evidence that muscles on the spastic-paretic side had less muscle mass, thicker fascia, and greater echo intensity. Our results showed that spasticity helped maintain muscle mass but failed to reveal additional muscle loss after botulinum toxin injection.