Neuroanatomy USMLE Step 1 Practice Question
A 34-year-old man presents to neurology with a 3-month history of progressive left leg weakness and spasticity. He reports recent-onset right-sided hearing loss and tinnitus. Vital signs are stable. Neurologic examination reveals 4/5 strength in left lower extremity with hyperreflexia and an extensor plantar response. Cranial nerve testing shows intact facial sensation bilaterally and normal eye movements. Audiometry confirms high-frequency sensorineural hearing loss on the right. MRI demonstrates a 2-cm T2-hyperintense mass at the cerebellopontine angle with expansion into the internal auditory canal. What is the embryologic origin of the lesion most consistent with this presentation?
Answer choices
- ANeural crest cells (Schwann cell origin)Correct answer
- BNeuroectodermal cells of the fourth ventricular floor
- CArachnoid cap cells of the meninges
- DMesodermal endothelial precursors
- EEpendymal remnants of the foramen of Magendie
- FVascular smooth muscle cells derived from neural crest
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