Dystonia--a clinical, neuropathological and therapeutic review.

Dystonia is a syndrome characterized by sustained muscle contractions frequently causing twisting and repetitive movements or abnormal posture. For diagnosis, prognosis and therapy, it is useful to classify dystonia with regard to types of abnormal movements present, their mode of activation and topographical distribution taking into account age of onset, and etiology. The majority of cases are idiopathic, or primary dystonias, while in a minority environmental, structural, or metabolic causes can be identified. Primary dystonias can be familial or sporadic. The most important neurophysiological phenomenon in dystonia is pathological cocontraction of antagonistic muscles, while there is no consistent neuropathological abnormality in idiopathic dystonia. Causal therapies for dystonia are only possible in a few symptomatic forms (M. Wilson, Segawa-syndrome). As a rule, treatment has to be symptomatic but results of systemic pharmacotherapies remain disappointing. For adult onset focal dystonias, a breakthrough in symptomatic therapy has been achieved with local "chemical" denervation by means of botulinum toxin type A injections.