Extrapyramidal Symptoms (EPS)

Introduction to EPS

Extrapyramidal symptoms (EPS) are a group of movement disorders that occur as side effects of medications that block dopamine receptors, particularly antipsychotics, and are characterized by involuntary movements or muscle rigidity affecting various body parts 1, 2

Involves sudden spastic contractions of distinct muscle groups, often affecting the neck or torso, typically occurs during the initial phases of treatment, and risk factors include young age, male gender, and use of high-potency antipsychotic agents 1
Presents with symptoms resembling Parkinson's disease, including bradykinesia, tremors, and rigidity, and can be difficult to differentiate from negative symptoms of schizophrenia or catatonia 1, 2, 4
Characterized by a subjective sense of severe restlessness and objective signs of motor restlessness, frequently manifests as pacing or physical agitation, and is commonly seen in patients treated with antipsychotics 1, 2

High-potency conventional antipsychotics have the highest risk, while low-potency conventional antipsychotics have lower EPS risk but more anticholinergic side effects 1, 2

Immediate treatment with anticholinergic medications such as intramuscular benztropine or diphenhydramine is recommended for acute dystonia 3
Reduce antipsychotic dose if clinically feasible, add anticholinergic agent or amantadine, and consider switching to a lower-potency agent or atypical antipsychotic for drug-induced parkinsonism 1
Reduce antipsychotic dose if possible, add β-blockers, and consider benzodiazepines for akathisia 1, 2

Children and adolescents may be at higher risk for EPS than adults, and monitoring for EPS is particularly important in youth due to limited studies in this population 1, 2
Some movement disorders may be misdiagnosed as EPS, including those associated with hepatic encephalopathy 4

Monitor patients closely, especially during initial treatment or dose increases, to prevent EPS 2