title: Sparing of the hippocampus indicates better collateral blood flow in acute posterior cerebral artery occlusion.
abstract: BACKGROUND
  In acute posterior cerebral artery, occlusion involvement of the hippocampus is a common finding. Nevertheless, until today, infarction and ischemic lesion evolution in the hippocampus has not been studied systematically.
  
  
  OBJECTIVE
  Evaluation of hippocampal infarction patterns in posterior cerebral artery occlusion in the very early phase (≤six-hours) and ischemic lesion evolution on follow-up magnetic resonance imaging in relation to collateral blood flow assessed by a magnetic resonance imaging-based approach was conducted.
  
  
  METHODS
  In 28 patients [mean age 69·4 ± 13·8 years, 19 (67·9%) males, 10 (32·1%) females] with proximal posterior cerebral artery occlusion, magnetic resonance imaging findings were analyzed, with emphasis on hippocampal infarction patterns on diffusion-weighted images and collateralization on dynamic 4D angiograms derived from perfusion-weighted raw images.
  
  
  RESULTS
  On initial diffusion-weighted images, we identified all known hippocampal infarction patterns: type 1 (complete) in 6/18 (33·3%) patients, type 2 (lateral) in 10/18 (55·6%) patients, and type 3 (dorsal) and type 4 (circumscribed) in 1/18 (5·6%) patient respectively. On dynamic 4D angiograms, the grade of collateralization was classified as 1 in 9 (32·1%), 2 in 1 (3·6%), 3 in 10 (35·7%), and 4 in 8 (28·6%) patients. On follow-up diffusion-weighted images, we found new ischemic lesions in three and infarction growth in the hippocampus in five patients. Patients with better collateralization (grades 3 and 4) less often had hippocampal infarctions on initial (P = 0·003)/follow-up diffusion-weighted images (P = 0·046) as well as type 1 on initial (P = 0·007)/follow-up diffusion-weighted images (P = 0·005).
  
  
  CONCLUSIONS
  Involvement of the hippocampus in proximal posterior cerebral artery occlusion is frequently but not obligatorily observed and highly dependent on the extent of collateralization. The same holds true for hippocampal infarction patterns.
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Alex
authors.initials: A
authors.lastname: Förster
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Mürle
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kerl
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Wenz
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Mansour
authors.initials: M
authors.lastname: Al-Zghloul
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Sonia
authors.initials: S
authors.lastname: Habich
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Groden
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology*; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005500:Follow-Up Studies; D006624:Hippocampus / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D020762:Infarction, Posterior Cerebral Artery / Q000473:pathology / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D020769:Posterior Cerebral Artery / Q000503:physiopathology*
keywords: PCA; collateral blood flow; hippocampus; stroke