Extrapyramidal Symptoms

Extrapyramidal symptoms are movement disturbances arising from dysfunction of the brain's extrapyramidal motor system, and when caused by medication they are called extrapyramidal side effects. They include dystonia, in which muscles contract involuntarily and continuously, akathisia, an inner restlessness that drives constant movement, parkinsonism, with rigidity and slowed movement, tremor, and tardive dyskinesia, marked by irregular, jerky, involuntary movements that can persist after the causal drug is stopped. The most common trigger is treatment with typical antipsychotic medications such as haloperidol and fluphenazine, though certain antiemetics and antidepressants can also cause them, and non-drug causes include brain injury and meningitis. These effects are clinically significant because they often lead patients to stop taking needed medication; in one major antipsychotic trial, extrapyramidal symptoms accounted for about 27 percent of all dropouts.