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Difficulty: HardMedical History Evaluation

A 68-year-old man is brought to the emergency department by his son because of progressive confusion, severe generalized muscle stiffness, and a high fever that developed over the past 24 hours. The patient has a past medical history of schizoaffective disorder, Parkinson disease, hypertension, and benign prostatic hyperplasia. Three days ago, he was discharged from a short-term rehabilitation facility where he had been recovering from a mild aspiration pneumonia. Vital signs upon arrival show a temperature of 39.7°C (103.5°F), blood pressure of 172/98 mmHg, heart rate of 115/min, and respiratory rate of 22/min. Physical examination is notable for profound diaphoresis, mutism, and severe "lead-pipe" rigidity in all four extremities. There is no clonus or hyperreflexia present. Laboratory studies reveal a creatine kinase level of 12,500 U/L and a white blood cell count of 16,500/mm³. Which of the following specific historical inquiries directed at the son are MOST essential to determine the primary etiology of this patient's condition? (Select 2)

  1. Were any high-potency antipsychotic medications newly prescribed or dose-escalated during his recent rehabilitation stay?Answer
  2. Was his home regimen of carbidopa-levodopa abruptly withheld or discontinued while he was in the facility?Answer
  3. C
    Has he been taking a selective serotonin reuptake inhibitor concomitantly with a monoamine oxidase inhibitor?
  4. D
    Did he receive any inhaled halogenated anesthetics for a procedure prior to his discharge?
  5. E
    Has he developed any new cough, purulent sputum, or worsening shortness of breath over the last 48 hours?

Answer

The most essential historical inquiries are whether high-potency antipsychotic medications were initiated or if his carbidopa-levodopa regimen was abruptly withheld.
The patient is presenting with a classic toxidrome characterized by altered mental status, autonomic instability, and severe "lead-pipe" muscle rigidity resulting in massive rhabdomyolysis (elevated CK). This triad is highly specific for a severe central dopaminergic derangement. The two life-threatening conditions that present identically in this manner are Neuroleptic Malignant Syndrome (NMS) and Parkinsonism-hyperpyrexia syndrome. NMS is triggered by central dopamine receptor antagonism, typically from initiating or escalating antipsychotic medications. Conversely, Parkinsonism-hyperpyrexia syndrome is triggered by the abrupt withdrawal or significant dose reduction of exogenous dopaminergic agents (such as carbidopa-levodopa). Because this patient has a history of both schizoaffective disorder and Parkinson disease, querying the sudden addition of an antipsychotic and the sudden removal of his Parkinson medication are the two most critical historical steps to establish the etiology.

Step-by-Step Solution

1
Analyze the clinical presentation and physical examination findings.
The patient presents with altered mental status, autonomic instability (hyperthermia, hypertension, tachycardia), severe lead-pipe rigidity, and massive creatine kinase elevation without clonus.
Identifying the specific toxidrome is the first step in narrowing the differential diagnosis.
2
Correlate the toxidrome with the patient's past medical history.
The combination of lead-pipe rigidity and autonomic instability points directly to a severe central dopaminergic disruption. The patient has both schizoaffective disorder (treated with dopamine antagonists) and Parkinson disease (treated with dopamine agonists).
This dual history creates two distinct pharmacological pathways to the same clinical endpoint.
3
Select the historical inquiries that evaluate these specific pathways.
Asking about the initiation of antipsychotics evaluates for Neuroleptic Malignant Syndrome, while asking about the withdrawal of Parkinson medications evaluates for Parkinsonism-hyperpyrexia syndrome.
Both conditions present identically and require opposite historical triggers (addition of an antagonist vs. removal of an agonist) to establish the correct diagnosis and guide management.

Key Concept

Neuroleptic Malignant Syndrome and Parkinsonism-hyperpyrexia syndrome are clinically identical emergencies resulting from central dopaminergic depletion; accurate diagnosis relies on careful medication history to identify either the initiation of dopamine antagonists or the withdrawal of dopamine agonists.
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Medical History Evaluation

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