Dystonia and its disorders.

Dystonia is a movement disorder characterized by sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. The term dystonia does not signify a single disease, but instead describes a symptom and sign that may be part of many disorders with a variety of causes. Dystonia may be classified by age of onset, distribution of symptoms, or by etiology. An increasing number of genetic forms of dystonia have been recognized and the findings have advanced knowledge of underlying neural mechanisms of pathogenesis. Options for treatment of dystonia include pharmacological therapy, botulinum toxin injection, or neurosurgical procedures.