title: Association of aneurysms and variation of the A1 segment.
abstract: OBJECTIVE
  Previous studies have described a correlation between variants of the circle of Willis and pathological findings, such as cerebrovascular diseases. Moreover, anatomic variations of the anterior cerebral artery (ACA) seem to correspond to the prevalence of aneurysms in the anterior communicating artery (ACoA). The aim of this study was to assess the prevalence of aneurysms in patients with anatomical/morphological variations of the circle of Willis.
  
  
  METHODS
  We retrospectively analyzed 223 patients who underwent cerebral angiography between January 2002 and December 2010 for aneurysm of the ACoA. Diagnostic imaging was reviewed and statistically evaluated to detect circle of Willis anomalies, aneurysm size, and rupture. 204 patients with an unrelated diagnosis served as the control group.
  
  
  RESULTS
  Variations of the A1 segment occurred significantly more frequently in the aneurysm group than in the control group. Mean aneurysm size in patients with grades I and III hypoplasia or aplasia was 6.58 mm whereas in patients with grade II hypoplasia it was 7.76 mm.
  
  
  CONCLUSIONS
  We found that variations in the A1 segment of the ACAs are correlated with a higher prevalence of ACoA aneurysms compared with patients with a symmetric circle of Willis.
authors.affiliation: Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Krasny
authors.forename: F
authors.initials: F
authors.lastname: Nensa
authors.forename: I E
authors.initials: IE
authors.lastname: Sandalcioglu
authors.forename: S L
authors.initials: SL
authors.lastname: Göricke
authors.forename: I
authors.initials: I
authors.lastname: Wanke
authors.forename: C
authors.initials: C
authors.lastname: Gramsch
authors.forename: S
authors.initials: S
authors.lastname: Sirin
authors.forename: N
authors.initials: N
authors.lastname: Oezkan
authors.forename: U
authors.initials: U
authors.lastname: Sure
authors.forename: M
authors.initials: M
authors.lastname: Schlamann
mesh_terms: D000368:Aged; D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging* / Q000209:etiology; D020771:Anterior Cerebral Artery / Q000002:abnormalities / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D002941:Circle of Willis / Q000002:abnormalities / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies
keywords: Aneurysm; Angiography; Hemorrhage