Neuroleptic Malignant Syndrome (NMS) is a rare but life-threatening reaction to neuroleptic (antipsychotic) medications. It is characterized by severe muscle rigidity, fever, autonomic instability, and altered mental status.
- Causes:
- Antipsychotic Medications: Most commonly associated with the use of typical antipsychotics (e.g., haloperidol, fluphenazine) but can also occur with atypical antipsychotics (e.g., risperidone, olanzapine).
- Rapid Increase in Medication Dosage: A quick escalation in the dose of neuroleptic medications increases the risk.
- Dehydration and Physical Stress: These factors may predispose individuals to NMS.
- Other Medications: Such as antiemetics (e.g., metoclopramide) that have dopamine antagonist properties.
- Parkinson’s Medications Withdrawal: Withdrawal of dopamine agonists
- Diagnosis:
- History (Hx):
- Recent initiation or dose increase of a neuroleptic medication.
- Prior history of NMS (if any).
- Any other medications taken, especially those affecting the dopaminergic system.
- Examination (Ex):
- Severe muscle rigidity (often described as “lead pipe” rigidity).
- Hyperthermia (high fever).
- Autonomic instability (e.g., blood pressure fluctuations, tachycardia, diaphoresis).
- Altered mental status ranging from agitation to confusion to coma.
- Investigations (Ix):
- Elevated Creatine Kinase (CK) due to muscle breakdown.
- Leukocytosis (increased white blood cell count).
- Electrolyte imbalances.
- Renal function tests (to check for myoglobinuria-induced renal damage).
- Liver function tests.
- EEG, CT, or MRI of the brain may be considered to rule out other causes.
- History (Hx):
- Differential Diagnosis (DDx):
- Serotonin Syndrome: Overlap in symptoms but usually associated with serotonergic medications.
- Malignant Hyperthermia: A reaction to anesthetic agents, not antipsychotics.
- Infections: Such as meningitis or encephalitis, especially with fever and altered mental status.
- Heat Stroke: Especially in the context of high environmental temperatures.
- Other causes of rigidity: Parkinsonism, catatonia, tetanus.
- Management (Mx):
- Discontinue Neuroleptic Medication: Immediate cessation of the offending agent.
- Supportive Care:
- Intensive monitoring, often in an intensive care unit.
- Cooling measures for hyperthermia.
- Hydration and correction of electrolyte imbalances.
- Close monitoring of renal function.
- Pharmacological Treatment:
- Benzodiazepines for sedation and muscle relaxation.
- Bromocriptine 2.5-5mg up to every 4 hours may be used in severe cases.
- Treatment of Complications: Such as renal failure or respiratory support for severe rigidity.
- Prevention: In patients with a history of NMS, alternative treatments to neuroleptics should be considered, and if neuroleptics are necessary, they should be reintroduced cautiously.
It’s crucial for healthcare providers to recognize the signs and symptoms of NMS early due to its potentially fatal nature. The management of NMS is primarily supportive, along with the discontinuation of the causative agent.