title: Absent collateral function of the circle of Willis as risk factor for ischemic stroke.
abstract: BACKGROUND
  Autopsy studies show a higher prevalence of circle of Willis anomalies in brains with signs of ischemic infarction. Our goal was to examine the collateral function of the circle of Willis in ischemic stroke patients and to assess in a case-control study if a collateral deficient circle of Willis is a risk factor for ischemic stroke in patients with severe internal carotid artery (ICA) occlusive disease.
  
  
  METHODS
  Our case-control study included 109 patients with an acute ischemic stroke in the anterior circulation and 113 patients with peripheral arterial disease and no known history of cerebral ischemia. The collateral function of the anterior and posterior communicating arteries of the circle of Willis was assessed by means of transcranial color-coded duplex ultrasonography (TCCD) and carotid compression tests.
  
  
  RESULTS
  TCCD was successfully performed in 75 case patients (mean age 64 years, range 41-91 years) and in 100 control patients (mean age 61 years, range 35-89 years). In 26 cases and 19 controls, a >/=70% stenosis or occlusion of the ICA was found. A nonfunctional anterior collateral pathway in the circle of Willis was found in 33% of the cases and in 6% of the controls (p < 0.001). The posterior collateral pathway was nonfunctional in 57% of the cases and in 43% of the controls (p = 0.02). In patients with severe ICA occlusive disease, the odds ratios of a nonfunctional anterior and a nonfunctional posterior collateral pathway were 7.33 (95% confidence interval, CI, = 1.19-76.52) and 3.00 (95% CI = 0.77-12.04), respectively.
  
  
  CONCLUSIONS
  Patients who suffer ischemic stroke in the anterior circulation have a higher incidence of collateral deficient circles of Willis than those with atherosclerotic vascular disease without ischemic cerebrovascular disease. The presence of a nonfunctional anterior collateral pathway in the circle of Willis in patients with severe ICA occlusive disease is strongly associated with ischemic stroke.
authors.affiliation: Department of Neurology, University Medical School, Debrecen, Hungary. a.hoksbergen@tiscali.nl
authors.forename: A W J
authors.initials: AW
authors.lastname: Hoksbergen
authors.forename: D A
authors.initials: DA
authors.lastname: Legemate
authors.forename: L
authors.initials: L
authors.lastname: Csiba
authors.forename: G
authors.initials: G
authors.lastname: Csáti
authors.forename: P
authors.initials: P
authors.lastname: Síró
authors.forename: B
authors.initials: B
authors.lastname: Fülesdi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016893:Carotid Stenosis / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016022:Case-Control Studies; D002941:Circle of Willis / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003097:Collateral Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D017585:Ultrasonography, Doppler, Transcranial