Neuroanatomy USMLE Step 1 Practice Question
A 55-year-old man with hypertension presents with acute onset loss of pain and temperature sensation over the right side of his face with preserved touch sensation, and dissociated loss of pain and temperature on the left body and limbs. Vital signs: BP 168/94, HR 82, RR 16, Temp 37°C. MRI brain shows acute infarction in the right rostral medulla. Cranial nerve examination is intact. What is the anatomic location of his lesion?
Answer choices
- ARight midbrain
- BRight thalamus
- CRight medulla (lateral medullary syndrome)Correct answer
- DLeft cervical spinal cord
- ERight pons at the level of the trigeminal nerve
- FRight nucleus ambiguus with ipsilateral corticospinal tract involvement
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.