title: Aneurysms increase the risk of rebleeding after stereotactic radiosurgery for hemorrhagic arteriovenous malformations.
abstract: OBJECTIVE
  The purpose of this study was to define the risk of rebleeding after stereotactic radiosurgery (SRS) for hemorrhagic arteriovenous malformations with or without associated intracranial aneurysms.
  
  
  METHODS
  Between 1987 and 2006, we performed Gamma Knife SRS on 996 patients with brain arteriovenous malformations; 407 patients had sustained an arteriovenous malformation hemorrhage. Sixty-four patients (16%) underwent prior embolization and 84 (21%) underwent prior surgical resection. The median target volume was 2.3 mL (range, 0.1-20.7 mL). The median margin dose was 20 Gy (range, 13.5-27 Gy).
  
  
  RESULTS
  The overall rate of total obliteration defined by angiography or MRI was 56%, 77%, 80%, and 82% at 3, 4, 5, and 10 years, respectively. Before obliteration, 33 patients (8%) sustained an additional hemorrhage after SRS. The overall annual hemorrhage rate until obliteration after SRS was 1.3%. The presence of a patent aneurysm was significantly associated with an increased rehemorrhage risk after SRS (annual hemorrhage rate, 6.4%) compared with patients with a clipped or embolized aneurysm (annual hemorrhage rate, 0.8%; P=0.033).
  
  
  CONCLUSIONS
  When an aneurysm is identified in patients with arteriovenous malformations selected for SRS, additional endovascular or surgical strategies should be considered to reduce the risk of bleeding during the latency interval.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kano
authors.forename: Douglas
authors.initials: D
authors.lastname: Kondziolka
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
authors.forename: Huai-che
authors.initials: HC
authors.lastname: Yang
authors.forename: Kyung-Jae
authors.initials: KJ
authors.lastname: Park
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Flannery
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Liu
authors.forename: Ajay
authors.initials: A
authors.lastname: Niranjan
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000792:Angiography; D016022:Case-Control Studies; D002543:Cerebral Hemorrhage / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016634:Radiosurgery; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult