A 62-year-old previously cognitively intact man presented to the emergency department with acute impairment of anterograde memory (ability to form new memories).1 Head CT did not show acute changes; however, amnesia persisted. MRI disclosed an acute infarct in the left posterior hippocampus and a nonacute lacunar stroke in the right anterior thalamus (figure). Memory testing showed severe deficits in verbal and visual memory, persisting after 2 months. Bilateral lesions located anywhere in the Papez circuit (hippocampal formations, mammillary bodies, anterior thalamic nuclei, cingulate and parahippocampal cortices, and their connections via fornix and mammillothalamic tracts) may be implicated in marked, persistent anterograde memory deficits.1,2 The hippocampus receives its blood supply from collateral branches of the posterior cerebral artery and the anterior choroidal artery.3 The anterior thalamus is supplied by the tuberothalamic artery.4

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