Embolic Hippocampal Infarct From Ipsilateral Tandem Carotid Stenosis: A Case Report and Lesson on Hippocampal Dual...

Although primarily supplied by the vertebrobasilar system, the hippocampus is partially supplied by ipsilateral carotid artery branches through the anterior choroidal artery or a prominent posterior communicating artery. We report a patient with acute hippocampus infarction likely due to symptomatic ipsilateral tandem carotid stenosis and discuss acute vascular-mediated hippocampal injury.

An 80-year-old female with obesity, dyslipidemia, hypertension, alcohol use disorder, history of breast cancer on letrozole, and traumatic brain injury was brought into our emergency department for 24 hours of confusion. On examination, she exhibited limited registration, recall, and executive dysfunction with otherwise normal language, visuo-spatial orientation, and praxis. Brain MRI showed a small area of diffusion restriction in the anterior right hippocampus with matched FLAIR hyperintensity, consistent with acute infarction. Computed tomography angiogram head and neck showed 90% stenosis of the proximal right internal carotid artery (ICA), <50% narrowing of the proximal left ICA, and moderate bilateral narrowing of the paraclinoid ICAs, all due to calcific atheromatous plaques. The etiology of the hippocampal infarction was suspected embolism from the ipsilateral severe carotid stenosis. Planning for right cervical carotid revascularization ensued.

This case highlights the dual hippocampal vascular supply and that hippocampal embolic infarcts could be a sign of a symptomatic severe carotid artery stenosis that may require urgent revascularization for stroke secondary prevention.