Botulinum toxin A injection in the management of shoulder muscle overactivity: A scoping review

The majority of studies examining botulinum toxin A (BTX-A) in the management of upper limb muscle overactivity and pain focus on the distal arm and hand. Research has begun to look at BTX-A efficacy in more proximal upper limb muscles, with literature showing equivocal findings. This scoping review identified 15 studies meeting inclusion criteria whose data were examined against three outcome variables: muscle overactivity, range of movement and pain. Overall, while the majority of injected participants improved on these variables, between-study methodological variability such as research design potentially underpowered studies and arbitrary decision making gave a high likelihood of influencing the interpretation of their results. Future research is warranted, with a robust focus on functional anatomy, a critical appraisal of how BTX-A may help the individual being studied and utilising individualised rather than protocol-driven research paradigms.