Botulinum toxin--mechanisms of action and clinical use in spasticity.

Botulinum toxin is a potent neurotoxin produced by the bacterium Clostridium botulinum. There are seven serotypes, all of which block the release of acetylcholine from nerve endings, which gives the compound its theoretical base for reducing spasticity. Initial studies of the use of botulinum toxin in the management of spasticity were promising and now there are a number of well-designed, double-blind, placebo-controlled studies that confirm the place of botulinum toxin in our treatment armoury against focal spasticity. The studies have demonstrated both efficacy and safety. There is still more work to be done in terms of disability although early reports confirm functional improvements, particularly reduction of pain as well as improvements in nursing care, hygiene and carer burden. Further studies also need to be done to confirm the place of botulinum toxin in the overall context of other treatment possibilities in the management of spasticity.