Tardive dyskinesia.

The movement disorder may appear after prolonged use of antipsychotic agents. Differential diagnosis includes hereditary, infectious, toxic and drug-induced causes of extrapyramidal dysfunction. Pathophysiology appears to be related to induced changes in dopamine neuronal function and may represent irreversible extrapyramidal synaptic modification. Treatment includes removing the offending agent when possible or using the lowest effective dose if the medication cannot be totally discontinued. Indiscriminate use of antipsychotic agents in nonpsychotic patients should be avoided.