A 60-year-old woman with pernicious anemia presents with paresthesias, loss of vibration sense, and spastic weakness in the lower extremities. MRI shows demyelination of the posterior and lateral columns of the spinal cord. What is the underlying deficiency?
- A Vitamin D
- B Vitamin B12 (Cobalamin) ✓
- C Vitamin B1 (Thiamine)
- D Vitamin B6 (Pyridoxine)
Correct answer: B. Vitamin B12 (Cobalamin)
Explanation
Subacute combined degeneration of the spinal cord is caused by vitamin C12 deficiency, classically due to pernicious anemia. It damages the posterior columns (vibration, proprioception) and lateral corticospinal tracts (motor). Thiamine deficiency causes Wernicke encephalopathy and beriberi.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.