Effect of botulinum toxin A injection on gait parameters in patients with post stroke spastic equinus deformity of foot, a randomized control trial

Post-stroke spastic equinus deformity is a common issue among stroke survivors, where the ankle and foot is held in the plantarflexed position and there is difficulty with voluntary dorsiflexion of the ankle, primarily caused by spasticity of the ankle plantar flexors (gastrocnemius and soleus muscles), impacting gait and leading to kinetic and kinematic abnormalities. Effectively addressing post-stroke spasticity is paramount for improving the quality of life for stroke survivors, fostering increased mobility, independence, and overall well-being. Early recognition, appropriate management, and sustained rehabilitation efforts are vital components in optimizing outcomes for those grappling with post-stroke spasticity.

Management involves a multidisciplinary approach, incorporating medication, physical and occupational therapy, and in some cases, advanced interventions like botulinum toxin A injection or surgery.  Botulinum toxin A has been approved for clinical use in spasticity management. It operates by selectively inhibiting the release of acetylcholine at the neuromuscular junction, thereby inducing muscle paralysis, which lasts for 3 to 6 months, with improvements in walking time and functional outcomes. It has been shown to be effective in managing spastic equinovarus deformity after a stroke, helping reduce muscle spasticity and improve functional outcomes.

There is insufficient data on the effect of an Indian manufactured Botulinum Toxin A on the gait parameters and spasticity at the ankle causing equinus in stroke. The present study is hence designed to study the effect of the same on gait and spastic equinus.

This randomized double blinded placebo-controlled study will be conducted in the department of neurological rehabilitation, NIMHANS, Bengaluru. 40 subjects with post-stroke spasticity, meeting the inclusion and exclusion criteria, will be recruited in the study after thorough neurological and clinical examination. The recruited participants will be given either botulinum toxin A injection, or saline injection, on day 1 or 2 after admission, based on the randomization.

The randomization and allocation will be done by a professional (outside the department) not involved in the administration of injection or the collection of data. The randomization will be done in 5 blocks of 8 each. Each vial (botulinum toxin A and placebo - empty vial with vacuum seal) will have a unique identification number and will look identical. The order of administration of the injection (after blinding and randomization) will be handed over to an investigator in sealed envelopes. The participants, injector and outcome assessor will be blinded to the group allocation. Validation of the sealed envelope technique will be done at the time of injection by a person who is not a part of the investigating team.

Participants in the Botulinum toxin A injection group will receive 100 U (diluted with 2 ml normal saline) of botulinum toxin A in the medial & lateral heads of Gastrocnemius (2:1 ratio as medial head is bulkier) . So medial head will receive 65 U and lateral head 35 U) under ultrasound guidance. Placebo group participants will receive 2 ml of  0.9% normal saline in divided doses in both the medial and lateral heads of Gastrocnemius (2:1 ratio). The injection procedure will be done on the 1 or 2 days of admission by the PI of the project. Patients in both the groups will receive inpatient rehabilitation, ankle-foot orthosis, will avail 12 sessions of physiotherapy in the form of stretching exercise of Tendo-Achilles, weight bearing and conventional gait training. Outcome measures will be recorded at baseline (pre-injection) and at end point (3 weeks after injection). The duration of the study is 24 months. Data analysis will be done post the clinical study.