title: Testing the radiosurgery-based arteriovenous malformation score and the modified Spetzler-Martin grading system to predict radiosurgical outcome.
abstract: OBJECTIVE
  The aim of this study was to validate the radiosurgery-based arteriovenous malformation (AVM) score and the modified Spetzler-Martin grading system to predict radiosurgical outcome.
  
  
  METHODS
  One hundred thirty-six patients with brain AVMs were randomly selected. These patients had undergone a linear accelerator radiosurgical procedure at a single center between 1989 and 2000. Patients were divided into four groups according to an AVM score, which was calculated from the lesion volume, lesion location, and patient age (Group 1, AVM score <1; Group 2, AVM score 1-1.49; Group 3, AVM score 1.5-2; and Group 4, AVM score >2). Patients with a Spetzler-Martin Grade III AVM were divided into Grades IIIA (lesion >3 cm) and IIIB (lesion <3 cm). Sixty-two female (45.6%) and 74 male (54.4%) patients with a median age of 37.5 years (mean 37.5 years, range 5-77 years) were followed up for a median of 40 months. The median tumor margin dose was 15 Gy (mean 17.23 Gy, range 15-25 Gy). The proportions of excellent outcomes according to the AVM score were as follows: 91.7% for Group 1, 74.1% for Group 2, 60% for Group 3, and 33.3% for Group 4 (chi-square test, degrees of freedom (df) = 3, p < 0.001). Based on the modified Spetzler-Martin system, Grade I lesions had 88.9% excellent results; Grade II, 69.6%; Grade IIIB, 61.5%; and Grades IIIA and IV, 44.8% (chi-square test, df = 3, p = 0.047).
  
  
  CONCLUSIONS
  The radiosurgery-based AVM score can be used accurately to predict excellent results following a single radiosurgical treatment for AVM. The modified Spetzler-Martin system can also predict radiosurgical results for AVMs, thus making it possible to use this system while deciding between surgery and radiosurgery.
authors.affiliation: Division of Neurosurgery and Department of Radiation Oncology, Sunnybrook and Women's College Health Sciences Center, University of Toronto, Ontario, Canada.
authors.forename: Yuri M
authors.initials: YM
authors.lastname: Andrade-Souza
authors.forename: Gelareh
authors.initials: G
authors.lastname: Zadeh
authors.forename: Meera
authors.initials: M
authors.lastname: Ramani
authors.forename: Daryl
authors.initials: D
authors.lastname: Scora
authors.forename: May N
authors.initials: MN
authors.lastname: Tsao
authors.forename: Michael L
authors.initials: ML
authors.lastname: Schwartz
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000145:classification* / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016634:Radiosurgery / Q000379:methods*; D012720:Severity of Illness Index; D016896:Treatment Outcome