Extrapyramidal Symptoms (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
Types of Extrapyramidal Symptoms
1. Acute Dystonia
- Involves sudden spastic contractions of distinct muscle groups, often affecting the neck (torticollis), eyes (oculogyric crisis), or torso 1
- Typically occurs during the initial phases of treatment, usually within 3-5 days after starting antipsychotics or increasing the dosage 2
- Risk factors include young age, male gender, and use of high-potency antipsychotic agents 1
- Can be extremely distressing and potentially life-threatening in cases of laryngospasm 1
- Usually responds well to anticholinergic or antihistaminic medications 1, 3
2. Drug-Induced Parkinsonism
- Presents with symptoms resembling Parkinson's disease, including:
- Bradykinesia (slowed movements)
- Tremors
- Rigidity 1
- Generally appears within the first three months of treatment 2
- Can be difficult to differentiate from negative symptoms of schizophrenia or catatonia 1
- Treated with anticholinergic agents, amantadine, or by reducing the antipsychotic dose 1, 2
3. Akathisia
- Characterized by a subjective sense of severe restlessness and objective signs of motor restlessness 1
- Frequently manifests as pacing, inability to sit still, or physical agitation 1
- Commonly seen in patients treated with antipsychotics 1
- Often misinterpreted as psychotic agitation or anxiety 1
- A common reason for medication noncompliance 1
- Difficult to treat; approaches include lowering antipsychotic dose, β-blockers, or benzodiazepines 1, 2
4. Tardive Dyskinesia
- Characterized by involuntary, repetitive movements, typically of the face and mouth 4
- Develops with long-term use of antipsychotics 4
- Can be permanent even after medication discontinuation 5
- Treatment options include VMAT2 inhibitors like valbenazine 6
Medications Associated with EPS
- High-potency conventional antipsychotics (e.g., haloperidol) have the highest risk 1
- Low-potency conventional antipsychotics (e.g., chlorpromazine) have lower EPS risk but more anticholinergic side effects 1
- Atypical antipsychotics have lower but variable EPS risk (risperidone highest, clozapine and quetiapine lowest) 5
- Non-antipsychotic medications that can cause EPS include certain antiemetics, antidepressants, lithium, and some anticonvulsants 7
Management of EPS
Acute Dystonia
- Immediate treatment with anticholinergic medications such as intramuscular benztropine 1-2 mg or diphenhydramine 25-50 mg 3
- Consider prophylactic anticholinergic agents for high-risk patients or those with history of dystonic reactions 3
Drug-Induced Parkinsonism
- Reduce antipsychotic dose if clinically feasible 2
- Add anticholinergic agent or amantadine 1
- Consider switching to a lower-potency agent or atypical antipsychotic 2
Akathisia
- Reduce antipsychotic dose if possible 1
- Add β-blockers (especially propranolol or metoprolol) 2
- Benzodiazepines may provide relief 1
- Anticholinergic agents are less consistently helpful 1
Special Considerations
- Children and adolescents may be at higher risk for EPS than adults 1
- Monitoring for EPS is particularly important in youth due to limited studies in this population 1
- Some movement disorders may be misdiagnosed as EPS, including those associated with hepatic encephalopathy 1
- The term "EPS" has been criticized for lack of clinical, anatomical, and physiologic precision, with some experts suggesting more specific phenomenological descriptors 8
Prevention Strategies
- Use the lowest effective dose of antipsychotic medication 2
- Consider atypical antipsychotics with lower EPS risk when appropriate 5
- Monitor patients closely, especially during initial treatment or dose increases 1
- Prophylactic anticholinergic agents may be considered for high-risk patients, though long-term prophylaxis remains controversial 2