If Neuroleptic Malignant Syndrome occurs in the setting of Parkinson's disease, typically when dopaminergic treatment is withdrawn, management is similar to NMS from other causes. However, it is critical that the Parkinsonian medication is re-instituted as quickly as possible. Drug holidays are no longer recommended for Parkinson's disease due to the risk of triggering this syndrome. If a neuroleptic is to be reintroduced, a waiting period of at least two weeks for oral medication and six weeks for parenteral medication should be observed. It is prudent to use a different neuroleptic than the one that originally caused the syndrome.
ℹ️ About
- Neuroleptic Malignant Syndrome (NMS): A rare but life-threatening condition seen in individuals taking antipsychotic medications.
- Occurs in approximately 1 in 200 individuals treated with neuroleptic drugs.
- Mortality rates can be as high as 10%, especially if not promptly treated.
Mechanism
- Loss of Dopaminergic Function: NMS is caused by a sudden and severe reduction in dopamine activity in the brain, often triggered by neuroleptic medications or abrupt withdrawal of dopaminergic drugs.
Causes
- Neuroleptics: Antipsychotic drugs like Haloperidol, Metoclopramide, and others that block dopamine receptors.
- Withdrawal of L-Dopa: Abrupt cessation of levodopa therapy in patients with Parkinson's disease.
- Withdrawal of Dopamine Agonists: Stopping medications like pramipexole or ropinirole can also trigger NMS.
🩺 Clinical Features
- Systemic Signs: Fever (pyrexia), tachycardia, and autonomic instability (blood pressure fluctuations, sweating).
- Neuromuscular Signs: Severe muscle rigidity ("lead pipe" rigidity), tremors, and dysphagia.
- Central Nervous System Signs: Impaired consciousness, delirium, stupor, and in extreme cases, catatonia.
- Other Risks: Exhaustion, dehydration, hyponatraemia (low sodium), and rhabdomyolysis (muscle breakdown leading to kidney injury).
🔎 Investigations
- Laboratory Findings:
- Increased white cell count (WCC) and C-reactive protein (CRP).
- Creatine kinase (CK) levels >1000 IU/L, indicating muscle breakdown.
- Elevated creatinine, signaling potential kidney damage.
- Other Tests: Check calcium, magnesium, thyroid function tests (TFTs) to exclude other metabolic causes.
💊 Management
- Supportive Care: Immediate stabilization using ABC approach (Airway, Breathing, Circulation). Intensive care may be required, including cooling measures and aggressive hydration.
- Dantrolene: 1-25 mg/kg IV to reduce muscle rigidity and hyperthermia.
- Dopaminergic Agents: Bromocriptine (dopamine agonist) or Amantadine may help restore dopaminergic function.
- Advanced Interventions: In severe cases, patients may need paralysis, intubation, and mechanical ventilation.
- Electroconvulsive Therapy (ECT): Can be particularly effective in refractory cases or if the patient is deteriorating despite medical therapy.
