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Difficulty: MediumMedical History Evaluation

A 24-year-old male is brought to the emergency department by his roommates due to severe agitation, confusion, and profuse sweating that began 6 hours ago. The roommates report that for the past three days, he has had a low-grade fever, runny nose, and a dry cough. He also sprained his right ankle two days ago while playing basketball. His past medical history is significant for major depressive disorder and seasonal allergic rhinitis. He underwent an uncomplicated appendectomy at age 12. He does not use tobacco or illicit drugs, and drinks alcohol occasionally. His prescribed daily medications are escitalopram and cetirizine. The roommates mention that to manage his recent symptoms, he has been taking leftover tramadol prescribed for a previous sports injury, along with an over-the-counter cough syrup containing dextromethorphan. On physical examination, his temperature is 39.4°C (102.9°F), blood pressure is 165/95 mmHg, and heart rate is 128/min. The patient is visibly diaphoretic with flushed skin and dilated pupils. Neurologic examination reveals tremor, hyperreflexia, and sustained clonus in the bilateral lower extremities. Based on a thorough evaluation of this patient's history and presentation, which of the following is the most likely diagnosis?

  1. A
    Viral meningoencephalitis
  2. B
    Neuroleptic malignant syndrome
  3. Serotonin syndromeAnswer
  4. D
    Anticholinergic toxicity
  5. E
    Malignant hyperthermia

Answer

Serotonin syndrome
The correct diagnosis is serotonin syndrome. This patient's history of polypharmacy is the critical diagnostic key. He is taking three distinct medications that increase central serotonergic neurotransmission: escitalopram (a selective serotonin reuptake inhibitor), tramadol (which inhibits serotonin reuptake), and dextromethorphan (which also inhibits serotonin reuptake). The synergistic effect of these drugs has precipitated a classic triad of altered mental status (confusion, agitation), autonomic instability (hyperthermia, tachycardia, diaphoresis, hypertension), and neuromuscular hyperactivity (tremor, hyperreflexia, sustained clonus). Proper medical history evaluation must carefully account for over-the-counter and unprescribed medications, as they are the primary drivers of this patient's acute pathology.

Step-by-Step Solution

1
Evaluate the patient's complete medication history, including both prescribed and over-the-counter agents.
The patient is taking escitalopram (an SSRI), tramadol (a weak opioid with serotonin reuptake inhibition properties), and dextromethorphan (an NMDA receptor antagonist that also inhibits serotonin reuptake).
Identifying all active pharmacologic agents is essential for recognizing toxidromes, as patients often fail to report over-the-counter or borrowed medications.
2
Correlate the comprehensive medication history with the physical examination findings.
The triad of altered mental status, autonomic instability (diaphoresis, tachycardia, hyperthermia), and neuromuscular hyperactivity (hyperreflexia, clonus) strongly aligns with excessive serotonergic activity.
Neuromuscular findings, specifically hyperreflexia and clonus, reliably differentiate this specific toxidrome from other causes of fever and altered mental status.

Key Concept

Identifying serotonin syndrome by evaluating a comprehensive history of polypharmacy involving multiple serotonergic agents (e.g., SSRIs, tramadol, dextromethorphan).
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Topics

Medical History Evaluation

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