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Difficulty: Very hardSubstance-Related and Addictive Disorders

Match each atypical patient clinical presentation with the most likely substance intoxication syndrome.

  • A 22-year-old man rapidly alternates between a profound, unarousable coma and severe, combative agitation. He exhibits significant bradycardia but awakens spontaneously and completely after 3 hours.Gamma-hydroxybutyrate (GHB) intoxication
  • A 26-year-old man exhibits extreme agitation, severe paranoia, and violent behavior lasting for over 48 hours. Routine urine toxicology is negative, and he requires continuous intravenous sedation.Synthetic cathinone ('bath salts') intoxication
  • A 17-year-old boy presents with severe ataxia, dissociative visual hallucinations, hyperreflexia, and inducible ankle clonus after consuming a large quantity of an over-the-counter liquid.Dextromethorphan intoxication
  • A 15-year-old boy presents with ataxia and slurred speech. Examination reveals an erythematous, scaling perioral rash. Laboratory studies demonstrate a normal anion gap metabolic acidosis and hypokalemia.Toluene (inhalant) intoxication

Answer

The correct matches are: the patient with alternating coma and agitation matches GHB; the patient with prolonged 48-hour delirium matches synthetic cathinones; the patient with ataxia and clonus matches dextromethorphan; and the patient with a perioral rash and metabolic acidosis matches toluene.
Each clinical vignette contains pathognomonic features that definitively link to only one substance. GHB uniquely causes alternating coma and agitation. Synthetic cathinones cause unusually prolonged delirium not seen with standard stimulants. Dextromethorphan uniquely combines NMDA antagonism with serotonin syndrome. Toluene uniquely causes Type 1 RTA alongside typical inhalant effects.

Step-by-Step Solution

1
Analyze the first presentation for highly specific temporal and neurologic features.
Identify the rapid cycling between profound coma and combativeness, resolving in a few hours.
GHB has a very narrow therapeutic index and unique receptor pharmacodynamics (GABA-B) that cause rapid clinical state shifts from deep central nervous system depression to severe agitation.
2
Evaluate the second presentation focusing on duration and toxicology results.
Identify the prolonged multi-day delirium with negative standard urine toxicology.
Amphetamine analogs found in synthetic cathinones evade standard immunoassay detection and have significantly longer half-lives than traditional stimulants like cocaine.
3
Correlate the third presentation's mix of dissociative and neuromuscular symptoms.
Recognize the combination of dissociation (NMDA antagonism) and hyperreflexia/clonus (serotonergic toxicity).
Dextromethorphan is the only commonly abused over-the-counter substance that simultaneously acts as an NMDA antagonist and a serotonin reuptake inhibitor.
4
Analyze the fourth presentation's dermatological and acid-base abnormalities.
Connect the perioral rash with the laboratory finding of normal anion gap metabolic acidosis and hypokalemia.
Chronic or subacute toluene inhalation causes distal renal tubular acidosis (Type 1 RTA) and a characteristic perioral contact dermatitis.

Key Concept

Differentiating atypical or lesser-known substance intoxications through unique clinical identifiers (e.g., fluctuating consciousness, prolonged duration, specific toxidrome combinations, and acid-base disturbances).
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Topics

Substance-Related and Addictive Disorders

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