extrapyramidal symptoms
Movement disorders caused by antipsychotic medications affecting the brain's motor control systems.
Full Definition
Extrapyramidal symptoms (EPS) are drug-induced movement disorders that commonly occur as side effects of antipsychotic medications. These symptoms result from blockade of dopamine receptors in the basal ganglia and include acute dystonia (involuntary muscle contractions), parkinsonism (tremor, rigidity, bradykinesia), akathisia (restlessness and inability to sit still), and tardive dyskinesia (late-onset involuntary movements). In psychiatric clinical trials, EPS are monitored using standardized rating scales such as the Abnormal Involuntary Movement Scale (AIMS) or Simpson-Angus Scale. The incidence and severity of EPS can significantly impact medication tolerability and patient compliance, making them important safety endpoints in antipsychotic drug development.
Usage
Usage note: Can be abbreviated as EPS after first use. Distinguish from specific subtypes like tardive dyskinesia.
In Context
- "Extrapyramidal symptoms were assessed using the Simpson-Angus Scale at each study visit." — safety assessment protocol
- "The novel antipsychotic demonstrated a lower incidence of extrapyramidal symptoms compared to haloperidol." — efficacy and safety results