title: Natural history of brain arteriovenous malformations: a systematic review.
abstract: OBJECTIVE
  The authors aimed to systematically review the literature to clarify the natural history of brain arteriovenous malformations (BAVMs).
  
  
  METHODS
  The authors searched PubMed for one or more of the following terms: natural history, brain arteriovenous malformations, cerebral arteriovenous malformations, and risk of rupture. They included studies that reported annual rates of hemorrhage and that included either 100 patients or 5 years of treatment-free follow-up.
  
  
  RESULTS
  The incidence of BAVMs is 1.12-1.42 cases per 100,000 person-years; 38%-68% of new cases are first-ever hemorrhage. The overall annual rates of hemorrhage for patients with untreated BAVMs range from 2.10% to 4.12%. Consistently implicated in subsequent hemorrhage are initial hemorrhagic presentation, exclusively deep venous drainage, and deep and infrantentorial brain location. The risk for rupture seems to be increased by large nidus size and concurrent arterial aneurysms, although these factors have not been studied as thoroughly. Venous stenosis has not been implicated in increased risk for rupture.
  
  
  CONCLUSIONS
  For patients with BAVMs, although the overall risk for hemorrhage seems to be 2.10%-4.12% per year, calculating an accurate risk profile for decision making involves clinical attention and accounting for specific features of the malformation.
authors.affiliation: Department of Neurological Surgery, University of Washington, Seattle, Washington.
authors.forename: Isaac Josh
authors.initials: IJ
authors.lastname: Abecassis
authors.forename: David S
authors.initials: DS
authors.lastname: Xu
authors.forename: H Hunt
authors.initials: HH
authors.lastname: Batjer
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Bendok
mesh_terms: D001165:Arteriovenous Malformations / Q000150:complications / Q000453:epidemiology / Q000473:pathology; D001921:Brain / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000209:etiology*; D003251:Constriction, Pathologic; D006801:Humans; D015994:Incidence; D012307:Risk Factors
keywords: BAVM = brain arteriovenous malformation; brain arteriovenous malformation; cerebral arteriovenous malformation; natural history; risk factors; risk of rupture