Neuromuscular Disorders USMLE Step 1 Practice Question
A 58-year-old man presents with progressive hand weakness and muscle cramps over 6 months. Vital signs: BP 128/82, HR 88, RR 16, Temp 37.0°C, SpO2 98%. Examination reveals fasciculations in forearms, spasticity in legs, hyperreflexia, and bilateral upgoing plantar responses. Sensory examination is intact throughout. Serum creatine kinase is mildly elevated at 320 U/L. Electromyography shows denervation patterns in multiple myotomes. Which of the following is the most likely diagnosis?
Answer choices
- ASpinal muscular atrophy
- BAmyotrophic lateral sclerosisCorrect answer
- CMultiple sclerosis
- DMyasthenia gravis
- EGuillain Barré syndrome
- FPrimary lateral sclerosis (PLS)
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