title: Management and clinical outcome of posterior fossa arteriovenous malformations: report on a single-centre 15-year experience.
abstract: OBJECTIVE
  Posterior fossa brain arteriovenous malformations (PFbAVMs) are rare lesions. Management is complicated by eloquence of adjacent neurological structures, multimodality treatment is often necessary, and obliteration is not always possible. We describe a 15-year experience in the management of posterior fossa brain AVMs with a focus on clinical outcome.
  
  
  METHODS
  From 1989 to 2004, prospectively collected information on 106 patients with diagnosis of a PFbAVMs was obtained. Clinical and angioarchitectural characteristics, management options and complications are described and reviewed to evaluate their impact on final outcome as measured by the Modified Rankin Score (mRS).
  
  
  RESULTS
  Ninety-eight patients were followed for an average of 3.3 years (1-14.6). The male-to-female ratio was 1:1. Ninety-five out of 98 patients (96.9%) were symptomatic at presentation, with 61 (62.2%) intracranial haemorrhages. Sixty-two patients were treated (46 cerebellar, 16 brainstem). Ten haemorrhages occurred in follow-up (4.1%/year). The mRS was obtained in 62 patients and was classified as low (good, mRS<or=2) or high (poor, mRS>or=3). Haemorrhage was the only predictor of poor mRS at presentation (p = 0.0229). A poor clinical outcome was correlated with the presence of AA (p = 0.0276), a poor initial mRS (p<0.0001) and the number of treatments needed (p = 0.0434). Patients were significantly more likely to improve than to deteriorate over time (p = 0.0201).
  
  
  CONCLUSIONS
  The final clinical outcome in PFbAVMs relates directly with the presence of associated aneurysms, number of treatments needed to obliterate the AVM and mRS at presentation. Despite the fact that patients tend to improve after brain AVM haemorrhage, the relationship of MRS at presentation and final outcome suggests that an expedited, more definitive treatment is probably a better choice, especially in patients with good grades after the initial bleeding.
authors.affiliation: Department of Medical Imaging, Division of Neuroradiology, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada. leo.dacosta@sunnybrook.ca
authors.forename: L
authors.initials: L
authors.lastname: da Costa
authors.forename: L
authors.initials: L
authors.lastname: Thines
authors.forename: A R
authors.initials: AR
authors.lastname: Dehdashti
authors.forename: M C
authors.initials: MC
authors.lastname: Wallace
authors.forename: R A
authors.initials: RA
authors.lastname: Willinsky
authors.forename: M
authors.initials: M
authors.lastname: Tymianski
authors.forename: M L
authors.initials: ML
authors.lastname: Schwartz
authors.forename: K G
authors.initials: KG
authors.lastname: ter Brugge
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology* / Q000601:surgery; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D007223:Infant; D002532:Intracranial Aneurysm / Q000209:etiology / Q000473:pathology; D002538:Intracranial Arteriovenous Malformations / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D011446:Prospective Studies; D016634:Radiosurgery; D016896:Treatment Outcome; D055815:Young Adult