Neuromuscular Disorders USMLE Step 1 Practice Question
A 23-year-old woman presents to the emergency department with severe colicky abdominal pain, anxiety, and acute proximal arm and leg weakness. Vital signs show BP 148/92 mmHg, HR 102/min, RR 18/min, Temp 37.2°C. She recently started phenobarbital for insomnia. Urine is dark red and darkens further on standing. Serum sodium is 128 mEq/L. Cranial nerves and sensation remain intact. Which of the following best explains her weakness?
Answer choices
- ADemyelination caused by Campylobacter infection
- BInherited absence of dystrophin
- CAcute motor neuropathy due to porphyrin pathway dysfunctionCorrect answer
- DCalcium channel antibodies associated with lung cancer
- EAutoimmune destruction of neuromuscular junction receptors
- FHyponatremia-induced osmotic demyelination of pontine and extrapontine structures
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