This week’s edition of the Step 1 Question of the Week is about neurology. See if you can answer the question and then watch the video to learn the correct answer as well as the rationales for each option.
An 80-year-old man comes to the clinic with occasional loss of consciousness when tilting his head back. He has diabetes and hypertension, along with a 50-pack-year smoking history. History includes a left carotid endarterectomy and surgical repair of an abdominal aortic aneurysm several years ago. It is determined that the patient is likely experiencing transient brainstem ischemia when he extends his neck.
Occlusion of which of the following vessels would most likely produce these symptoms?