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Difficulty: MediumSubstance-Related and Addictive Disorders

An emergency department physician is evaluating several patients presenting with acute psychiatric and physiologic changes related to substance use. Correlate each clinical vignette with the most appropriate diagnosis.

  • A patient exhibiting multidirectional nystagmus, aggressive behavior, hyperthermia, and a profound lack of pain response to venipuncture.Phencyclidine (PCP) intoxication
  • A patient presenting with intense dysphoria, profound fatigue, ravenous appetite, psychomotor retardation, and reports of intensely disturbing dreams.Stimulant withdrawal
  • A patient demonstrating prominent conjunctival erythema, inappropriate laughter, mild tachycardia, and sluggish psychomotor responses.Cannabis intoxication
  • A patient experiencing rhinorrhea, frequent yawning, diaphoresis, hyperactive bowel sounds, and prominent piloerection on the arms.Opioid withdrawal

Answer

PCP intoxication pairs with nystagmus and analgesia; Stimulant withdrawal pairs with dysphoria and vivid dreams; Cannabis intoxication pairs with conjunctival erythema; Opioid withdrawal pairs with rhinorrhea and piloerection.
Each vignette represents the classic, highest-yield diagnostic signs for the respective toxidromes as frequently tested on Step 2 CK. PCP is identified by multidirectional nystagmus, stimulant withdrawal by the somnolent 'crash', cannabis by conjunctival injection, and opioid withdrawal by piloerection and rhinorrhea.

Step-by-Step Solution

1
Analyze the first presentation for distinguishing neurological signs.
The presence of multidirectional nystagmus combined with analgesia and agitation points to PCP intoxication.
PCP uniquely causes rotary or multidirectional nystagmus alongside dissociative anesthesia.
2
Evaluate the second presentation for a post-use 'crash' pattern.
Profound fatigue, vivid dreams, and ravenous appetite align with stimulant withdrawal.
Stimulant depletion leads to rebound hypersomnolence, hyperphagia, and severe dysphoria.
3
Identify the primary physiological signs in the third presentation.
Conjunctival erythema with inappropriate laughter indicates cannabis intoxication.
Cannabis classically causes vasodilation in the conjunctiva and euphoric or inappropriate affect.
4
Examine the fourth presentation for autonomic hyperactivity and mucosal secretions.
Yawning, rhinorrhea, and piloerection point to opioid withdrawal.
Loss of opioid receptor agonism leads to sympathetic and mucosal rebound, creating flu-like symptoms and piloerection.

Key Concept

Identifying specific physiological and psychiatric hallmarks of distinct substance intoxication and withdrawal toxidromes.
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Topics

Substance-Related and Addictive Disorders

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