[Acute dystonia].

Acute dystonia is a side effect of antipsychotic medication; it nearly always develops a few weeks after the start of a dopamine-blocking agent or substantial increase of the dosage. Acute dystonia is characterized as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. The risk of acute dystonia depends greatly on the presence of risk factors: early age, male sex, use of cocaine, a history of acute dystonia, and use of a highly potent antipsychotic agent in a normal dosage. The mechanism underlying acute dystonia is unknown: both increase and decrease of the striatal dopamine transmission have been put forward as possible causes. Acute dystonia may also be caused by dopamine-blocking agents that are used not as antipsychotic medication but, for instance, as anti-emetics. Anticholinergic agents are extremely efficacious in treatment as well as prevention of acute dystonia. Prophylaxis of acute dystonia is indicated for patients belonging to the risk groups.