CNS Pharmacology USMLE Step 1 Practice Question
A 35-year-old man with no prior psychiatric history presents to the emergency department with acute-onset disorganized speech, paranoid delusions, and agitation. Vital signs are BP 145/92 mmHg, HR 98 bpm, RR 16/min, temperature 37.2°C, and SpO2 98% on room air. Urine drug screen is negative. He is administered haloperidol 10 mg IM for behavioral control. Two hours later, nursing staff reports the patient has developed sustained leftward neck deviation, jaw clenching, involuntary upward eye rolling, and apparent distress. Neurological examination reveals no focal motor deficits, normal reflexes, and normal strength. Which of the following is the most appropriate immediate intervention?
Answer choices
- AAdminister additional haloperidol to increase dopamine blockade and overcome the acute extrapyramidal effect
- BAdminister lorazepam 2 mg IV to reduce muscle tension and provide sedation
- CAdminister benztropine 1-2 mg IV or IMCorrect answer
- DInitiate cooling measures and observe for spontaneous resolution within 6-12 hours
- EAdminister diphenhydramine 50 mg IM as the sole treatment for symptom relief
- FPerform urgent CT/MRI of the head to rule out intracranial pathology
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