Does Ketamine Cause Extrapyramidal Syndrome?
No, ketamine does not cause extrapyramidal syndrome (EPS). Ketamine is not associated with dopamine receptor blockade or extrapyramidal side effects in the medical literature.
Mechanism and Evidence
Ketamine operates through a completely different mechanism than drugs that cause EPS. The available evidence discusses ketamine's effects on:
- Hemodynamic parameters (sympathomimetic activity, blood pressure, heart rate) 1, 2
- Respiratory effects (increased secretions, bronchodilation) 1
- Dissociative symptoms (emergence reactions in 10-30% of adults, including hallucinations and delirium) 2
- Psychotomimetic effects (occurring in approximately 20% of patients at 0.5 mg/kg) 3
None of the guideline literature identifies EPS as a side effect of ketamine.
Drugs That Actually Cause EPS
The evidence clearly identifies the medications that do cause extrapyramidal symptoms:
High-Risk Agents
- High-potency antipsychotics (e.g., haloperidol) produce the most EPS through dopamine receptor blockade 1
- Low-potency antipsychotics (e.g., thioridazine, chlorpromazine) cause less EPS but more anticholinergic effects 1
Other Causative Agents
- Selective serotonin reuptake inhibitors (SSRIs), particularly escitalopram, can cause EPS through serotonergic input to dopaminergic pathways 4
- Certain antidepressants, antiemetics, lithium, and rarely anticonvulsants can produce EPS indistinguishable from neuroleptic-induced symptoms 5, 6
Clinical Implications
If a patient on ketamine develops extrapyramidal symptoms, look for concomitant medications or other causes. The EPS is not from the ketamine itself. Common EPS presentations include:
- Acute dystonia (sudden muscle spasms, oculogyric crisis) 1
- Parkinsonism (bradykinesia, tremors, rigidity) 1
- Akathisia (severe restlessness, pacing) 1, 4
- Tardive dyskinesia (involuntary movements, typically orofacial) 1
Children and adolescents are at higher risk for EPS from antipsychotics than adults, but this is irrelevant for ketamine use 1.