Neuromuscular Disorders USMLE Step 1 Practice Question
A 62-year-old man with a 50 pack-year smoking history presents with dry mouth, constipation, and progressive proximal leg weakness. He reports strength improves transiently after climbing stairs. Vital signs: BP 138/82, HR 88, RR 16, Temp 37°C, SpO2 98%. Examination shows diminished reflexes that normalize after exercise. Serum calcium is 11.2 mg/dL. There is no sensory loss. Which of the following is the most likely diagnosis?
Answer choices
- AGuillain Barré syndrome
- BLambert Eaton myasthenic syndromeCorrect answer
- CBotulism
- DAmyotrophic lateral sclerosis
- EMyasthenia gravis
- FParaneoplastic sensory neuronopathy (anti-Hu syndrome)
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.