This week, we are sharing another USMLE® Step 1-style practice question to test your knowledge of medical topics. Today’s case focuses on a 35-year-old-man who has a temperature is 100°F (37.7 °C), pulse is 117 bpm, respiratory rate is 18 breaths per minute, and blood pressure is 177/90 mmHg. The patient has noted mydriasis bilaterally during physical examination. Can you figure it out?
A 35-year-old man is brought to the emergency department by EMS after he was found at a public park yelling at bystanders. Several unlabeled pill capsules are found in his belongings. Temperature is 100°F (37.7 °C), pulse is 117 bpm, respiratory rate is 18 breaths per minute, and blood pressure is 177/90 mmHg. The patient appears agitated and diaphoretic. On physical examination, the patient has noted mydriasis bilaterally. There is absence of clonus in the lower extremities bilaterally. Oral mucosa appears moist. Intranasal examination reveals septal ulceration. Which of the following is the most likely etiology of this patient’s clinical presentation?
A. Cannabis intoxication
B. Serotonin syndrome
C. Amphetamine intoxication
D. Opiate withdrawal syndrome
E. Benzodiazepine intoxication
The correct answer to today’s USMLE® Step 1 Question is…
A. Amphetamine Intoxication
Before we get to the Main Explanation, let’s look at the incorrect answer explanations. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
The incorrect answers to today’s USMLE® Step 1 Question are…
A. Cannabis Intoxication
Incorrect: Symptoms of cannabis intoxication include conjunctival injection, increased appetite, euphoria, paranoid delusions and a dry mouth. Pupillary dilation and diaphoresis are not typical of cannabis intoxication.
B. Serotonin Syndrome
Incorrect: Serotonin syndrome is characterized by hyperactive reflexes, mydriasis, and hyperadrenergic drive. One of the key findings in cases of serotonin syndrome is the presence of clonus, which is absent in this patient.
D. Opiate Withdrawal Syndrome
Incorrect: Opiate withdrawal syndrome may manifest with many similar features of amphetamine intoxication syndrome including mydriasis, tachycardia, and hypertension. However, patients with opiate withdrawal syndrome will also typically exhibit piloerection, vomiting, and diarrhea.
E. Benzodiazepine Intoxication
Incorrect: Psychomotor depression, respiratory depression, ataxia, and hypotension are features of benzodiazepine intoxication. A normal respiratory rate and hypertension as seen in this patient suggests an alternative diagnosis.
Main Explanation
This patient presents with psychomotor agitation, tachycardia, hypertension, septal ulceration, and aggressive behavior – suggestive of stimulant intoxication. Cocaine and associated amphetamines (MDMA, ecstasy, methamphetamine) are psychoactive stimulants with varying effects on the enhancement of dopaminergic, serotonergic, and noradrenergic activity in the central nervous system. Non-specific features of stimulant intoxication include anxiety, aggressive behavior, psychomotor agitation, delirium, hypertension, tachycardia, pupillary dilation, mydriasis and diaphoresis. In high doses, hallucinations and paranoia may be present. In addition, serotonin syndrome may ensue if multiple, or high quantities of, serotonergic agents are ingested.
Abrupt cessation of stimulant use manifests with effects opposite to the intoxicating effects. These features include hypersomnia, increased appetite, pupillary constriction, psychomotor retardation and depression.
Leave a Reply