Pilot Study on Muscle, Tendon, and Neural Changes Post-Botulinum Toxin Injections in Post-stroke Spastic Equinovarus

Recruiting now · Not applicable

Conditions studied: Stroke, Spasticity, Equinovarus Foot

In brief

Poststroke spasticity significantly impairs function, particularly through the development of pes equinovarus. Botulinum toxin A (BoNT) injections into the medial gastrocnemius (MG) are a first-line treatment. Treatment outcomes and long-term responses to interventions can vary significantly between individual patients. Additionally, there is increasing concern about potential adverse effects on muscle morphology. Further research is essential to optimize treatment strategies and improve long-term outcomes in this population. Three-dimensional freehand ultrasound (3DfUS) and instrumented spasticity assessment (ISA) are two recently developed techniques that enable the evaluation of changes in muscle, tendon, and neural properties following BoNT injections for post-stroke spastic equinovarus. These methods hold promise for providing new insights into treatment effects. Before implementing these techniques in large-scale studies, a pilot study is required for accurate sample size calculations for a prospective observational study. This study includes a protocol for a non-blinded, non-randomized open-label longitudinal pilot study. The study was approved by the European Medicines Agency ( EU CT Number 2024-513158-32) by the University Hospitals Leuven ethical committee (ID S68672). Standard deviations and effect sizes of outcome measures obtained longitudinally with 3DfUS and ISA before and after BoNT injection into MG will inform sample size calculations for future research.

Key facts

Study ID: NCT06767631
Run by: Universitaire Ziekenhuizen KU Leuven
People needed: 12
Starts: 2025-05-02
Expected to finish: 2027-12-31
Last updated by the study team: 2026-04-29

Who can join

Age: 40 and older, up to 60. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any screening procedures
2. At least 18 years of age at the time of signing the Informed Consent Form (ICF)
3. Use of highly effective methods of birth control; defined as those that, alone or in combination, result in low failure rate (i.e., less than 1% per year) when used consistently and correctly; such as implants, injectables, combined oral contraceptives, some IUDs, true sexual abstinence (i.e. refraining from heterosexual intercourse during the entire period of risk associated with the Trial treatment(s)) or commitment to a vasectomised partner.
4. Pes equinovarus due to spasticity
5. Clinical need for BoNT injection at the lower leg
6. Any previous injection of BoNT into the muscles to be investigated was at least 3 months ago
7. First-ever, unilateral stroke

You may not qualify if…

Musculoskeletal or other neurological problems affecting the lower limb
Presence of spinal cord pathology that could lead to spasticity, ataxia, dystonia
Cognitive problems that impede measurements
Severe co-morbidities
Irritated skin or open wounds where ultrasound will be placed
Pregnancy
Profound atrophy of the muscles in the target area(s) of injection
Participation in an interventional Trial with an investigational medicinal product (IMP) or device
The effect of botulinum toxin A can theoretically be potentiated by agents affecting neuromuscular transmission, such as aminoglycoside antibiotics (e.g., gentamicin, tobramycin), lithium salts, cholinesterase inhibitors and tubocurarine-like muscle relaxants ((cis)atracurium, rocuronium, suxamethonium, vecuronium). Therefore, patients on whom these medications are started during the course of the trail will be excluded.

Where it is running

Uz Leuven — Leuven, Belgium (enrolling)

Full record on ClinicalTrials.gov

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