Neuromuscular Disorders USMLE Step 1 Practice Question
A 37-year-old woman presents 18 hours after consuming improperly canned vegetables with blurred vision, dysphagia, and progressive descending symmetric paralysis. Vital signs: BP 138/82, HR 98, RR 16, Temperature 37.2°C, SpO2 98% on room air. Examination reveals fixed dilated pupils and facial weakness. Serum electrolytes are normal. She denies recent antibiotic use. Which of the following best explains this clinical presentation?
Answer choices
- AAntibody mediated destruction of nicotinic receptors
- BNeuronal degeneration in the substantia nigra
- CToxin mediated inhibition of glycine release in the spinal cord
- DAntibody mediated demyelination of peripheral nerves
- EToxin mediated inhibition of acetylcholine release at peripheral cholinergic synapsesCorrect answer
- FToxin mediated inhibition of acetylcholinesterase at the neuromuscular junction
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.