Neurodegenerative Diseases USMLE Step 1 Practice Question
A 64 year old man presents with progressive gait instability and numbness in both feet. He underwent total gastrectomy 3 years ago for gastric cancer. Examination shows decreased vibration and position sense in the lower extremities, spasticity, and a positive Romberg sign. Hemoglobin is 10.1 g/dL with MCV 112 fL. Which of the following is the most likely pathophysiologic mechanism?
Answer choices
- ACopper deposition in the basal ganglia
- BCompression of the cauda equina nerve roots
- CDemyelination of dorsal columns and lateral corticospinal tractsCorrect answer
- DIschemic necrosis of the mammillary bodies
- EAutoimmune destruction of Schwann cells
- FAxonal degeneration of peripheral sensory neurons due to thiamine deficiency
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