Examkin

Question

Difficulty: MediumSubstance-Related and Addictive Disorders

A 17-year-old boy is brought to the emergency department by his parents after experiencing a generalized tonic-clonic seizure at home. The seizure lasted approximately 2 minutes. His parents report that he has become increasingly irritable, secretive, and academically withdrawn over the past month. Earlier today, they heard a loud noise and found him convulsing on his bedroom floor next to an electronic vaping device and an unlabeled vial of liquid. On current evaluation, the patient is highly agitated, diaphoretic, and pacing around the room. He expresses intense paranoia, claiming that the medical staff are trying to harvest his organs. Vital signs show a temperature of 37.7°C (99.9°F), blood pressure of 160/100 mmHg, and heart rate of 128/min. Physical examination is notable for prominent bilateral conjunctival injection. Horizontal and vertical gaze nystagmus are absent. A standard comprehensive urine toxicology screen is negative for all tested substances. Which of the following is the most likely cause of this patient's clinical presentation?

  1. Synthetic cannabinoid intoxicationAnswer
  2. B
    Phencyclidine intoxication
  3. C
    Cannabis intoxication
  4. D
    Cocaine intoxication
  5. E
    3,4-Methylenedioxymethamphetamine intoxication

Answer

Synthetic cannabinoid intoxication
The clinical picture of a young patient presenting with a new-onset seizure, severe agitation, intense paranoia, and sympathetic overstimulation (tachycardia, hypertension, diaphoresis) alongside bilateral conjunctival injection is highly characteristic of synthetic cannabinoid intoxication. Unlike traditional marijuana (tetrahydrocannabinol), which is a partial agonist at the CB1 receptor, synthetic cannabinoids (often sold as 'Spice' or 'K2' in liquid form for electronic vaporizers) are potent full agonists at the CB1 receptor. This full agonism leads to much more severe and life-threatening effects, including extreme psychosis, combativeness, acute kidney injury, and seizures. A critical diagnostic clue is that synthetic cannabinoids do not cross-react with standard urine toxicology assays designed to detect THC metabolites, resulting in a negative drug screen despite profound clinical toxicity.

Step-by-Step Solution

1
Analyze the clinical signs and symptoms
The patient exhibits severe agitation, intense paranoia, tachycardia, hypertension, diaphoresis, new-onset seizures, and prominent conjunctival injection.
Identifying the specific toxidrome helps narrow down the causative substance.
2
Evaluate the diagnostic findings
The standard urine toxicology screen is completely negative, and there is no nystagmus on physical examination.
A negative toxicology screen rules out common illicit substances that typically appear on standard panels (like THC, cocaine, PCP, and amphetamines).
3
Synthesize the findings to determine the most likely substance
The combination of severe sympathomimetic symptoms, seizures, conjunctival injection, and a negative routine drug screen in the context of vaping strongly points to synthetic cannabinoids.
Synthetic cannabinoids act as full agonists at CB1 receptors, producing much more severe neurologic and psychiatric effects than traditional cannabis, and they avoid detection on standard assays.

Key Concept

Synthetic cannabinoid intoxication presents with severe psychiatric symptoms (extreme agitation, psychosis), prominent sympathetic overactivity, seizures, and conjunctival injection, typically with a negative standard urine toxicology screen.
Estimated Time:1m 30s
Rate this question

Topics

Substance-Related and Addictive Disorders

More questions from this topic