Are treatments with botulinum toxin injections effective in all cases? If not in what cases are they ineffective?
If spasticity affects only one or two specific parts of your body, you may be given botulinum toxin as an injection. The benefit of botulinum toxin has been established for various muscles affected by spasticity. The effects of botulinum toxin usually last for about three months. Botulinum toxin treatment should be given with further rehabilitation such as physiotherapy, or other treatments like splinting or casting. You should also have an assessment three to four months after the treatment.
source: Stroke Association (2012) Pain after stroke