[Botulinum toxin: mechanism of action]

Inhibitory effect of botulinum toxin on acetylcholine release from the neurons of peripheral nervous system and morphological changes produced in neuro-muscular junction by administration of the toxin are discussed. Other possible mechanisms of action, which can be responsible for the therapeutic effect are presented. Two clinically important problems are discussed: spreading of the toxin from the site of injection, and immunization which is responsible for non-responsiveness in some cases.