Botulinum toxin type A injection in post-stroke spasticity produced significant reductions in fascial thickness across all evaluated regions, suggesting that its therapeutic effects 'may extend beyond neural inhibition to include fascial remodeling.'
Key Findings
Results
Fascial thickness decreased significantly across all evaluated muscle regions following BoNT-A injection in post-stroke spasticity patients.
37 patients with post-stroke spasticity were included in this retrospective observational study.
Fascial thickness was measured using ultrasonography at three timepoints: baseline, 3 weeks post-injection, and 3 months post-injection.
Repeated-measures analysis demonstrated significant reductions in fascial thickness across all evaluated regions.
Pairwise comparisons confirmed significant decreases from baseline to both week 3 and month 3.
Results
Continued fascial thickness reductions between week 3 and month 3 were observed only in specific anatomical regions.
Progressive reductions between week 3 and month 3 were found in the flexor digitorum superficialis fascia.
The flexor digitorum superficialis-flexor digitorum profundus interfascial layer also showed continued reduction between week 3 and month 3.
The deep brachialis fascia was the third region showing continued reductions between the two follow-up timepoints.
Other evaluated regions did not show statistically significant continued reductions between week 3 and month 3.
Results
Modified Ashworth Scale scores improved significantly following BoNT-A injection.
MAS scores were assessed as a clinical outcome measure alongside ultrasonographic measurements.
Significant improvement in MAS scores was observed over the study period.
MAS measures muscle tone and spasticity on a standardized scale commonly used in stroke rehabilitation.
Results
Upper extremity Fugl-Meyer Assessment scores improved significantly, while Brunnstrom stages remained unchanged.
Upper extremity FMA scores showed significant improvement following BoNT-A treatment.
Brunnstrom stages, which assess motor recovery stages post-stroke, did not show statistically significant changes.
The dissociation between FMA improvement and unchanged Brunnstrom stages suggests differential sensitivity of these outcome measures to BoNT-A treatment effects.
Discussion
The study proposes that ultrasonographic assessment of fascial thickness may serve as an imaging biomarker for monitoring structural treatment responses in post-stroke spasticity.
Fascial thickness changes were detectable via ultrasonography at both 3 weeks and 3 months post-injection.
The authors suggest this measure could capture non-neural, structural components of treatment response not reflected by standard clinical scales.
The finding that fascial remodeling continued beyond 3 weeks in select regions indicates a time-dependent structural response to BoNT-A.
Discussion
Post-stroke spasticity involves both neural and non-neural mechanisms including structural alterations of muscles and surrounding fascia, which BoNT-A may address through fascial remodeling.
The study identifies fascial structural changes as a component of post-stroke spasticity beyond the well-established neural inhibition mechanism of BoNT-A.
The authors state that therapeutic effects of BoNT-A 'may extend beyond neural inhibition to include fascial remodeling.'
This retrospective study design limits causal inference but provides longitudinal observational data across three timepoints.
What This Means
This research suggests that botulinum toxin injections (commonly known as Botox) used to treat muscle stiffness after stroke do more than just relax overactive nerves — they may also physically remodel the tough connective tissue (fascia) that surrounds muscles. Researchers used ultrasound imaging to measure the thickness of fascia in the forearms and upper arms of 37 stroke patients before treatment, three weeks after injection, and three months after injection. They found that fascial thickness decreased significantly at all measured sites, and in three specific tissue layers, the fascia continued to thin even between the three-week and three-month measurements, suggesting an ongoing structural change over time.
Alongside these structural findings, patients also showed meaningful improvements in clinical measures of muscle stiffness (Modified Ashworth Scale) and arm movement ability (Fugl-Meyer Assessment), though their overall stage of motor recovery (Brunnstrom stage) did not change significantly. This suggests that while the treatment reduces stiffness and improves some functional arm movements, it may not fundamentally alter the broader pattern of motor recovery after stroke.
This research suggests that ultrasound measurement of fascial thickness could become a useful tool for doctors to objectively track how a patient's tissue is responding to treatment over time — going beyond what standard clinical scales can detect. It also opens the possibility that part of the benefit of botulinum toxin injections in stroke patients comes from physical changes to connective tissue, not just nerve-related effects, which could eventually influence how rehabilitation and follow-up treatments are planned.