title: Postradiosurgery hemorrhage rates of arteriovenous malformations of the brain: influencing factors and evolution with time.
abstract: OBJECTIVE
  The long-term benefit of radiosurgery of brain arteriovenous malformations (AVM), especially nonhemorrhagic cases, is controversial. We calculated hemorrhage rates pre- and posttreatment and analyzed the risk factors for bleeding based on cases followed at our site.
  
  
  METHODS
  One hundred eight patients, age 36 ± 17 years, 56 men. The mean follow-up was 65 ± 44 months (median, 54; interquartile range, 33-94). Most AVMs were small (74.1% <3 cm in diameter); 48.1% were located in an eloquent area, 27.8% had deep drainage, and 39.8% presented with hemorrhage.
  
  
  RESULTS
  The annual hemorrhage rate for any undiagnosed AVM was 1.2%, and 3.3% for AVMs with hemorrhagic presentation. Older patients, cortical or subcortical AVMs, and cases with multiple draining veins were less likely to present with bleeding. During the first 36 months postradiosurgery, hemorrhagic AVMs had a rebleeding rate of 2.1%, and a rate of 1.1% from 3 years onwards. Nonhemorrhagic AVMs had a hemorrhage rate of 1.4% during the first 3 years and 0.3% afterward. Arterial hypertension and nidus volume were independent predictors of bleeding after treatment. Mean nidus obliteration time was 37 ± 18 months (median, 32; interquartile range, 25-40), with hemorrhage rate of 1.3% before and 0.6% after obliteration, and 1.9% for AVMs that were not closed at the end of follow-up.
  
  
  CONCLUSIONS
  Both hemorrhagic and nonhemorrhagic AVMs benefit from radiosurgical therapy, with gradual decrease in their bleeding rates over the years. Albeit small, the risk of hemorrhage persists during the entirety of follow-up, being higher for cases with hemorrhagic presentation and nonobliterated AVM.
authors.affiliation: Department of Neurology, Hospital Universitario la Fe, Valencia, Spain. parkhutic_ver@yahoo.com
authors.forename: Vera
authors.initials: V
authors.lastname: Parkhutik
authors.forename: Aida
authors.initials: A
authors.lastname: Lago
authors.forename: José Ignacio
authors.initials: JI
authors.lastname: Tembl
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Vázquez
authors.forename: Fernando
authors.initials: F
authors.lastname: Aparici
authors.forename: Esperanza
authors.initials: E
authors.lastname: Mainar
authors.forename: Víctor
authors.initials: V
authors.lastname: Vázquez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001164:Arteriovenous Fistula / Q000175:diagnosis / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000601:surgery*; D020300:Intracranial Hemorrhages / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D015995:Prevalence; D016634:Radiosurgery; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult