title: Computer modeling of anterior circulation stroke: proof of concept in cerebrovascular occlusion.
abstract: BACKGROUND
  Current literature emphasizes the role of the Circle of Willis (CoW) in salvaging ischemic brain tissue but not that of leptomeningeal anastomoses (LA). We developed a computational model of the cerebral circulation to (1) evaluate the roles of the CoW and LA in restoring flow to the superficial compartment of the middle cerebral artery (MCA) territory and (2) estimate the size of the LA required to maintain flow above the critical ischemic threshold (>30% of baseline) under simulated occlusion.
  
  
  METHODS
  Cerebral vasculature was modeled as a network of junctions connected by cylindrical pipes. The experiments included occlusion of successive distal branches of the intracranial arteries while the diameters of LA were varied.
  
  
  RESULTS
  The model showed that the region of reduced flow became progressively smaller as the site of occlusion was moved from the large proximal to the smaller distal arteries. There was no improvement in flow in the MCA territory when the diameters of the inter-territorial LA were varied from 0.0625 to 0.5 mm while keeping the intra-territorial LA constant. By contrast, the diameter of the inter-territorial LA needed to be >1.0 mm in order to provide adequate (>30%) flow to selected arteries in the occluded MCA territory.
  
  
  CONCLUSIONS
  The CoW and inter-territorial LA together play important supportive roles in intracranial artery occlusion. Computational modeling provides the ability to experimentally investigate the effect of arterial occlusion on CoW and LA function.
authors.affiliation: Stroke Unit, Monash Medical Centre and Stroke and Aging Research Group, Neurosciences Research Unit, Southern Clinical School, Monash University , Melbourne, VIC , Australia.
authors.forename: Thanh G
authors.initials: TG
authors.lastname: Phan
authors.affiliation: Mathematics, Informatics and Statistics, CSIRO , Clayton, VIC , Australia.
authors.forename: James
authors.initials: J
authors.lastname: Hilton
authors.affiliation: Stroke Unit, Monash Medical Centre and Stroke and Aging Research Group, Neurosciences Research Unit, Southern Clinical School, Monash University , Melbourne, VIC , Australia ; Developmental Imaging Group, Murdoch Childrens Research Institute , Parkville, VIC , Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Beare
authors.affiliation: Stroke Unit, Monash Medical Centre and Stroke and Aging Research Group, Neurosciences Research Unit, Southern Clinical School, Monash University , Melbourne, VIC , Australia.
authors.forename: Velandai
authors.initials: V
authors.lastname: Srikanth
authors.affiliation: Mathematics, Informatics and Statistics, CSIRO , Clayton, VIC , Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Sinnott
keywords: Circle of Willis; anatomy; computer modeling; leptomeningeal collateral; stroke