title: The natural history and predictive features of hemorrhage from brain arteriovenous malformations.
abstract: OBJECTIVE
  Patients harboring brain arteriovenous malformations (bAVMs) are at a lifelong risk for hemorrhagic strokes, but the natural history is poorly understood. We examined the impact of demographic and angiographic features on the likelihood of future hemorrhage.
  
  
  METHODS
  A prospectively accrued database of bAVM patients maintained at the Toronto Western Hospital was analyzed; 678 consecutive, prospectively enrolled bAVM patients were followed for 1931.7 patient-years. The rate of hemorrhage over long-term follow-up was recorded. The impact of baseline clinical and radiographic features and partial treatment on time to hemorrhage were analyzed using survival analysis. Neurological outcome after hemorrhage was assessed using the Glasgow Outcome Score.
  
  
  RESULTS
  Hemorrhage rates were 4.61% per year for the entire cohort (n=678), 7.48% per year for bAVMs with initial hemorrhagic presentation (n=258), 4.16% per year for initial seizure presentation (n=260), 3.99% per year for patients not harboring aneurysms (n=556), 6.93% per year for patients with associated aneurysms (n=122), and 5.42% per year for bAVMs with deep venous drainage (n=365). Hemorrhagic presentation was a significant independent predictor of future hemorrhage (HR, 2.15; P<0.01), whereas associated aneurysms (HR, 1.59; P=0.07) and deep venous drainage (HR, 1.59; P=0.07) showed a trend toward significance. Hemorrhage risk was unchanged in patients who underwent partial arteriovenous malformation embolization (n=211; HR, 0.875; P=0.32).
  
  
  CONCLUSIONS
  Brain arteriovenous malformations presenting with hemorrhage, with deep venous drainage, or associated aneurysms have approximately 2-fold greater likelihood of a future hemorrhage. Partial treatment by embolization does not alter these risks. This natural history should be taken into account in the treatment strategy.
authors.affiliation: Toronto Western Hospital, Division of Neurosurgery, Suite 4W-435, 399 Bathurst St, Toronto, Ontario, Canada. mike.tymianski@uhn.on.ca
authors.forename: Leodante
authors.initials: L
authors.lastname: da Costa
authors.forename: M Christopher
authors.initials: MC
authors.lastname: Wallace
authors.forename: Karel G
authors.initials: KG
authors.lastname: Ter Brugge
authors.forename: Cian
authors.initials: C
authors.lastname: O'Kelly
authors.forename: Robert A
authors.initials: RA
authors.lastname: Willinsky
authors.forename: Michael
authors.initials: M
authors.lastname: Tymianski
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction; D001165:Arteriovenous Malformations / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D002533:Cerebral Angiography; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002543:Cerebral Hemorrhage / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D002550:Cerebral Veins / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity / Q000639:trends; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult