Botulinum toxin in movement disorders.

Botulinum toxin inhibits the vesicular release of acetylcholine in the neuromuscular junction, resulting in a transient, localized paralysis when small doses are injected. The successful use of serotypes A and B in conditions with muscle overactivity such as dystonia and spasticity has been well established. Apart from approved indications, treatment with botulinum toxin injections is attempted in a variety of new areas of neurology, including tremor, tics, and myoclonus. This article provides an update on the uses of botulinum toxin in the field of movement disorders and draws special attention to theoretical and practical treatment issues of primary and secondary dystonic disorders. Long-term experience with this agent suggests that it is an effective and safe treatment not only for approved indications but also for the increasing number of off-label indications. However, controlled studies for many conditions are lacking, and more clinical trials in many different areas are warranted.