[Amnesic stroke caused by hippocampal infarction]

The term amnesic stroke is used to describe a condition in which the dominant symptom is a relatively persistent acute amnesia of a vascular origin. It may appear in cases of lesions in the posterior cerebral artery (PCA), thalamic arteries and anterior choroidal artery, and clinical reports describing this condition are scarce.

We describe the case of a 77-year-old male with vascular risk factors who presented sudden onset mnemonic deficit that affected basic activities of daily living, and apathy. Examination of the patient revealed an anterograde episodic amnesia with an inability to retain new information and short-term memory was also clearly affected, although access to old memories remained relatively intact. There was no other sensory-motor focus. A CAT scan showed a right-side sylvian infarction and hypodense areas in both hippocampuses. The neuropsychological evaluation revealed global amnesia: CME (in Spanish, MEC) 17/30; working memory with CME 7/27; SVF (animals): 7; the 7-minute test (visual/verbal memory: free recall 2/16, facilitated 9/16); clock test: 3/9. Later progression was good, with recovery of short-term memory and the capacity to retain concepts, and the patient was again able to perform the activities he previously carried out.

There are three amnesic stroke syndromes with different semiological characteristics, depending on the vascular territory, that is, the PCA, thalamic arteries and anterior choroidal artery. In this case, the most striking points are the more intense disorders affecting short-term memory and retention, with relative conservation of long-term memory, and the location of the stroke in the hippocampus. Its good outcome allows it to be distinguished from vascular dementia.