title: Risk of rupture of small anterior communicating artery aneurysms is similar to posterior circulation aneurysms.
abstract: OBJECTIVE
  According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (AC) aneurysms of <7 mm in diameter have a minimal risk of rupture. It is general experience, however, that anterior communicating artery (AcoA) aneurysms are frequent and mostly rupture at <7 mm. The aim of the study was to assess whether AcoA aneurysms behave differently from other AC aneurysms.
  
  
  METHODS
  Information about 932 patients newly diagnosed with intracranial aneurysms between November 1, 2006, and March 31, 2012, including aneurysm status at diagnosis, its location, size, and risk factors, was collected during the multicenter @neurIST project. For each location or location and size subgroup, the odds ratio (OR) of aneurysms being ruptured at diagnosis was calculated.
  
  
  RESULTS
  The OR for aneurysms to be discovered ruptured was significantly higher for AcoA (OR, 3.5 [95% confidence interval, 2.6-4.5]) and posterior circulation (OR, 2.6 [95% confidence interval, 2.1-3.3]) than for AC excluding AcoA (OR, 0.5 [95% confidence interval, 0.4-0.6]). Although a threshold of 7 mm has been suggested by ISUIA as a threshold for aggressive treatment, AcoA aneurysms <7 mm were more frequently found ruptured (OR, 2.0 [95% confidence interval, 1.3-3.0]) than AC aneurysms of 7 to 12 mm diameter as defined in ISUIA.
  
  
  CONCLUSIONS
  We found that AC aneurysms are not a homogenous group. Aneurysms between 4 and 7 mm located in AcoA or distal anterior cerebral artery present similar rupture odds to posterior circulation aneurysms. Intervention should be recommended for this high-risk lesion group.
authors.affiliation: From the Service de Neurochirurgie/Départment de Neurosciences Cliniques (Ph.B., M.J., A.R., K.S.), Division de Neuroradiologie Diagnostique et Interventionelle (V.M.P.), Division des Services Informatiques (J.I.), Faculté de Médecine de Genève and Hôpitaux Universitaire de Genève, Switzerland; Fraunhofer Institut Algorithmen und Wissenschaftliches Rechnen, Sankt Augustin, Germany (C.E., C.M.F.); Nuffield Department of Surgical Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom (P.S., J.B.); Royal Hallamshire Hospital and University of Sheffield, United Kingdom (A.W.); Hospital Clinic, Barcelona, Spain (J.M., J.B.); MTA-PTE MR-Research Group, Department of Neurosurgery, University of Pècs, Hungary (P.B.); Hospital General de Catalunya, San Cugat del Valles, Spain (E.V.); Erasmus University Medical Center, Rotterdam, The Netherlands (M.C.J.M.S.); Durham Law School, Durham University, England (J.W.); Information and Communication Technologies Department, Universitat Pompeu Fabra, Barcelona, Spain (A.F.); and Zentrum fur Neuroradiology, Clinic Hirslanden, Zürich (D.R.).
authors.forename: Philippe
authors.initials: P
authors.lastname: Bijlenga
authors.forename: Christian
authors.initials: C
authors.lastname: Ebeling
authors.forename: Max
authors.initials: M
authors.lastname: Jaegersberg
authors.forename: Paul
authors.initials: P
authors.lastname: Summers
authors.forename: Alister
authors.initials: A
authors.lastname: Rogers
authors.forename: Alan
authors.initials: A
authors.lastname: Waterworth
authors.forename: Jimison
authors.initials: J
authors.lastname: Iavindrasana
authors.forename: Juan
authors.initials: J
authors.lastname: Macho
authors.forename: Vitor Mendes
authors.initials: VM
authors.lastname: Pereira
authors.forename: Peter
authors.initials: P
authors.lastname: Bukovics
authors.forename: Elio
authors.initials: E
authors.lastname: Vivas
authors.forename: Miriam C J M
authors.initials: MC
authors.lastname: Sturkenboom
authors.forename: Jessica
authors.initials: J
authors.lastname: Wright
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Friedrich
authors.forename: Alejandro
authors.initials: A
authors.lastname: Frangi
authors.forename: James
authors.initials: J
authors.lastname: Byrne
authors.forename: Karl
authors.initials: K
authors.lastname: Schaller
authors.forename: Daniel
authors.initials: D
authors.lastname: Rufenacht
mesh_terms: D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000175:diagnosis*; D020771:Anterior Cerebral Artery / Q000503:physiopathology; D001488:Basilar Artery / Q000503:physiopathology; D002343:Carotid Artery, Internal / Q000503:physiopathology; D015331:Cohort Studies; D005060:Europe; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000145:classification / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000503:physiopathology; D016017:Odds Ratio; D020769:Posterior Cerebral Artery / Q000503:physiopathology; D012307:Risk Factors; D014711:Vertebral Artery / Q000503:physiopathology
keywords: SAH; intracranial aneurysm; registries; risk factors; subarachnoid hemorrhage