title: Large and deep brain arteriovenous malformations are associated with risk of future hemorrhage.
abstract: OBJECTIVE
  The correlation between features present in brain arteriovenous malformations (AVMs) such as size, location, and angioarchitecture at presentation with subsequent risk of hemorrhage may be valuable in predicting the behavior of AVMs and therefore guiding management.
  
  
  METHODS
  We prospectively followed up 390 patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Location, size, angioarchitecture details, blood supply, and clinical presentation were recorded at baseline. Intracranial hemorrhages during follow-up were recorded. Significant factors from univariate analyses were used to construct a multivariate model relating the above features to the occurrence of hemorrhage.
  
  
  RESULTS
  Thirty-eight patients had bleeding caused by the AVM in a follow-up of 1205 patient-years (mean, 3.1 years per patient). In analyses adjusted for multiple AVM characteristics, large AVMs bled more frequently than small lesions (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.41 to 4.35; P<0.0001), and deep-seated AVMs had more bleeding in follow-up than those located at superficial sites (OR, 5.56; 95% CI, 2.63 to 12.5; P<0.0001).
  
  
  CONCLUSIONS
  Deep-seated and large AVMs were significantly more prone to hemorrhage during prospective follow-up. The distinction between factors associated with hemorrhagic presentation and the natural history risk of hemorrhage will be emphasized.
authors: Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors: Marco A
authors: MA
authors: Stefani
authors: Phillip J
authors: PJ
authors: Porter
authors: Karel G
authors: KG
authors: terBrugge
authors: Walter
authors: W
authors: Montanera
authors: Robert A
authors: RA
authors: Willinsky
authors: M Christopher
authors: MC
authors: Wallace
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D002170:Canada / Q000453:epidemiology; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000453:epidemiology*; D002550:Cerebral Veins / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000145:classification* / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D018570:Risk Assessment; D016019:Survival Analysis