Hippocampal vascularization: Proposal for a new classification

Abstract

Background: Anatomy of the hippocampal arterial supply is key to successful surgeries in this area. The goal of the current study is to present the results we obtained from our microsurgical dissections of the temporal lobe and to propose a new classification for the hippocampal arteries (HAs). Methods: Fifty-six brain hemispheres were analyzed. All dissections in this study were made using 3–40× at the surgical microscope. Results: The hippocampal arterial vasculature can be divided into six groups, according to their frequencies: Group A: mixed arterial vasculature originating from the anterior choroidal artery anterior choroidal artery, posterior cerebral artery (PCA), anterior infratemporal artery (AIA), and splenic artery (SA). Group B: Main origin at the temporal branches – main inferotemporal trunk, middle inferotemporal artery, posterior inferotemporal artery, AIA, or main branch of PCA. Group C: AIA as the main branch of the hippocampus. Group D: HAs originating from the main branch of PCA. Group E: A single hippocampal artery with the origin at the main branch of PCA. This single artery covered all of the structure and is named Ushimura’s artery. Group F: The hippocampal vessels arose exclusively from the parieto-occipital artery, calcarine artery (CA), and the SA. Conclusion: This study proposes a new classification for the hippocampal vascularization, according to the origin of HAs. One of the groups has not yet been described in the literature – in which the HAs arise from the parieto-occipital artery, SA, and CA.

Forgetting the Unforgettable: Transient Global Amnesia Part I: Pathophysiology and Etiology

“…Recently, Isolan proposed adding a sixth group to this classification (F), in which the hippocampal arteries originate from branches of the P3 segment of the PCA (e.g., parieto-occipital artery and calcarine artery) and from the splenial artery (a branch of the parieto-occipital artery) [ 24 ] ( Table 1 ).…”

The Anatomy of the Hippocampus

“…Hippocampus is supplied by the branches of the posterior cerebral artery and anterior choroidal artery (1,8,30).…”

“…It joins with the posterior communicating artery to complete the circle of Willis (1,8). The posterior cerebral artery can be divided into four segments, and it gives three major branches: cortical branches, posterolateral striate branches, and posterior choroid artery (29,30). The second part of the posterior cerebral artery (from the posterior communicating artery to the posterior margin of the midbrain) gives the anterior inferior temporal artery and the anterior hippocampalparahippocampal artery which supply the entorhinal area (1,29,30).…”

“…In addition, the anterior choroid artery also supplies the optic tract, the uncus, the globus pallidus, lateral geniculate body, and the internal capsule. The perforating branches of the anterior choroid artery supplies the amygdala and the hippocampus (1,30).…”

“…The anterior hippocampal arteries supply the uncus and the head of the hippocampus, while the posterior hippocampal arteries supply the body and tail of the hippocampus (29,30) The blood vessels supplying the hippocampus have small calibers and are more prone to thrombus formation. The thrombosis of the hippocampal arteries leads to damage and death of pyramidal neurons of the hippocampus which is characteristic for Alzheimer's disease.…”