Investigating muscle selection for botulinum toxin-A injections in adults with post-stroke upper limb spasticity

Background: Limited empirical information exists regarding botulinum toxin-A injector decision-making practices for adult upper limb post-stroke spasticity. The design of most studies prevents such an assessment, as injection sites and dosage are mandated by researcher protocols. This contrasts to usual injector practices, where individualized decisionmaking is the standard of care. Design: Secondary data analysis from an Australian randomized controlled trial of 90 adults with upper limb poststroke spasticity where experienced clinicians followed their standard clinical injecting practice rather than a mandated injection regimen. Methods: Clinicians were hypothesized to tailor their injection practices according to the subject's degree of spasticity and/or the type of functional gain desired. Hypothesis testing was conducted using non-parametric analysis. Results: Muscle selection and botulinum toxin-A dosage were not significantly associated with spasticity severity or with patient-identified goals. Between-site differences in injection practices suggested that injector beliefs, rather than patient characteristics, were the dominant feature driving botulinum toxin-A injection strategy for post-stroke upper limb spasticity. Conclusion: This result looks into the "black box" of rehabilitation, revealing significant variation in injector beliefs. Findings suggest that further scientific work is required to maximize the efficacy of botulinum toxin-A injections in post-stroke upper limb spasticity management.