Neuroanatomy USMLE Step 1 Practice Question
A 45-year-old woman presents to the emergency department with acute onset of pain and temperature sensation loss in a cape-like distribution across both shoulders, upper arms, and forearms bilaterally. She reports a 2-year history of progressive neck pain. On examination, fine touch sensation and proprioception are intact in the lower extremities and trunk. Cranial nerves II-XII are intact. Deep tendon reflexes are 2+ throughout and symmetric. Cervical spine MRI reveals a fluid-filled cavity (syrinx) at the C4-C5 level with expansion of the spinal cord. Which of the following best explains the patient's sensory findings?
Answer choices
- ABilateral degeneration of the lateral corticospinal tracts causing motor weakness
- BCompression of the dorsal columns impairing vibration and proprioception
- CBilateral disruption of the spinocerebellar tracts causing loss of limb coordination
- DBilateral crossing of spinothalamic tract fibers at the affected spinal cord levelCorrect answer
- EDisruption of the dorsal root ganglia with loss of all sensory modalities
- FCompression of the ventral horns affecting motor neuron integrity
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