A 61-year-old woman with a 6-month history of progressive numbness in her feet and difficulty walking presents with blood pressure 142/88 mmHg, heart rate 78/min, and temperature 37.2°C. Examination reveals loss of vibration sense bilaterally, spasticity in lower extremities, and positive Babinski signs; proprioception is intact. Laboratory studies show macrocytosis with hypersegmented neutrophils and elevated methylmalonic acid. MRI brain demonstrates T2 hyperintensities in the dorsal spinal cord. Which of the following structures is most likely affected?
- A)Corticospinal tracts and dorsal columnsGABARITO
- B)Cerebellar vermis only
- C)Spinothalamic tracts only
- D)Basal ganglia only
- E)Anterior horn cells only
Explicação
Corticospinal tracts and dorsal columns is the correct answer because vitamin B12 deficiency causes subacute combined degeneration, producing impaired vibration and proprioception together with upper motor neuron signs from lateral corticospinal tract involvem... Ver explicação completa e trilha adaptativa →