Neuromuscular Disorders USMLE Step 1 Practice Question
A full-term newborn presents on day 1 of life with a weak cry, poor suck, and diffuse hypotonia. Vital signs show HR 145/min, RR 38/min, and normal oxygen saturation. The mother reports a 5-year history of fluctuating ptosis and diplopia that significantly worsened during pregnancy. She denies autoimmune disease but reports improvement with anticholinesterase medications. Serum electrolytes and glucose are normal in the infant. Which diagnosis best explains the clinical presentation?
Answer choices
- ABotulism
- BDuchenne muscular dystrophy
- CSpinal muscular atrophy
- DTransient neonatal myasthenia gravisCorrect answer
- ETetanus
- FCongenital myasthenia gravis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations ā plus adaptive practice that targets your weak areas ā with a free MedBoardPRO account.