Neuromuscular Disorders USMLE Step 1 Practice Question
A 46-year-old battery factory worker presents with acute wrist drop and foot drop. He reports abdominal pain, irritability, and constipation for 3 weeks. Vital signs: BP 148/92, HR 102, RR 18, Temp 37°C, SpO2 98%. Laboratory studies reveal microcytic anemia (Hgb 9.2 g/dL) with basophilic stippling on blood smear. Nerve conduction studies show slowed motor velocities. No cognitive changes noted. Which of the following is the most likely cause of his motor deficit?
Answer choices
- ALead induced motor neuropathy affecting radial nerve functionCorrect answer
- BPresynaptic calcium channel autoantibodies
- CPostsynaptic receptor blockade at the neuromuscular junction
- DInherited demyelination due to PMP22 duplication
- EAutoimmune destruction of anterior horn cells
- FOrganophosphate compound exposure causing irreversible acetylcholinesterase inhibition
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.