title: Direction of flow in posterior communicating artery on magnetic resonance angiography in patients with occipital lobe infarcts.
abstract: OBJECTIVE
  In some people the blood supply to the posterior cerebral artery occurs partly or even exclusively via the carotid system. This anatomic configuration may influence the risk of occipital lobe infarction. We studied the presence and direction of flow in the posterior communicating artery (PCoA) in patients with an occipital lobe infarct and in healthy controls.
  
  
  METHODS
  Forty-seven patients with an occipital lobe infarct were studied by MR angiography, as well as 50 young healthy controls. Special attention was paid to the presence of a PCoA and, if present, to the direction of flow.
  
  
  RESULTS
  Significantly fewer patients than controls had an exclusive blood supply to the posterior cerebral artery via the carotid system, in both the affected (4% versus 17%; 95% CI of difference, 4% to 22%) and unaffected hemispheres (5% versus 17%; 95% CI of difference, 3% to 22%). Patients also less often had a patent PCoA with anteroposterior flow than controls (affected hemisphere, 8% versus 22%; unaffected hemisphere, 12% versus 22%; 95% CI of differences, 3% to 25% and -2% to 23%, respectively). With analysis at the level of individuals, significantly more patients showed no anteroposterior flow through the PCoA in either hemisphere than controls (79% versus 42%; 95% CI of difference, 19% to 55%).
  
  
  CONCLUSIONS
  Supply of the posterior cerebral artery by the carotid system occurs less often in patients with an occipital lobe infarct than in healthy controls. The same was true for the unaffected hemisphere of patients, which suggests that the anatomic difference represents a causal factor (fewer collateral pathways after occlusion of the posterior cerebral artery or its branches) rather than a consequence (redistribution of blood flow after occipital infarction).
authors.affiliation: Department of Neurology, Hospital Zevenaar, PO Box 9000, 6900 GA Zevenaar, Netherlands.
authors.forename: Jacqueline C F
authors.initials: JC
authors.lastname: Jongen
authors.forename: Cees L
authors.initials: CL
authors.lastname: Franke
authors.forename: Lino M P
authors.initials: LM
authors.lastname: Ramos
authors.forename: Jan T
authors.initials: JT
authors.lastname: Wilmink
authors.forename: Jan
authors.initials: J
authors.lastname: van Gijn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D001783:Blood Flow Velocity; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000503:physiopathology; D002544:Cerebral Infarction / Q000175:diagnosis / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D002941:Circle of Willis / Q000000981:diagnostic imaging / Q000503:physiopathology; D003097:Collateral Circulation; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011446:Prospective Studies; D012016:Reference Values; D014057:Tomography, X-Ray Computed; D014654:Vascular Patency