title: A modified radiosurgery-based arteriovenous malformation grading scale and its correlation with outcomes.
abstract: OBJECTIVE
  The Pittsburgh radiosurgery-based arteriovenous malformation (AVM) grading scale was developed to predict patient outcomes after radiosurgery and was later modified with location as a two-tiered variable (deep vs. other). The purpose of this study was to test the modified radiosurgery-based AVM score in a separate set of AVM patients managed with radiosurgery.
  
  
  METHODS
  The AVM score is calculated as follows: AVM score = (0.1)(volume, cc) + (0.02)(age, years) + (0.5)(location; frontal/temporal/parietal/occipital/intraventricular/corpus callosum/cerebellar = 0, basal ganglia/thalamus/brainstem = 1). Testing of the modified system was performed on 293 patients having AVM radiosurgery from 1992 to 2004 at the University of Pittsburgh with dose planning based on a combination of stereotactic angiography and MRI. The median patient age was 38 years, the median AVM volume was 3.3 cc, and 57 patients (19%) had deep AVMs. The median modified AVM score was 1.25. The median patient follow-up was 39 months.
  
  
  RESULTS
  The modified AVM scale correlated with the percentage of patients with AVM obliteration without new deficits (≤1.00, 62%; 1.01-1.50, 51%; 1.51-2.00, 53%; and >2.00, 32%; F = 11.002, R(2) = 0.8117, p = 0.001). Linear regression also showed a statistically significant correlation between outcome and dose prescribed to the margin (F = 25.815, p <0.001).
  
  
  CONCLUSIONS
  The modified radiosurgery-based AVM grading scale using location as a two-tiered variable correlated with outcomes when tested on a cohort of patients who underwent both angiography and MRI for dose planning. This system can be used to guide choices among observation, endovascular, surgical, and radiosurgical management strategies for individual AVM patients.
authors.affiliation: Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
authors.forename: Rodney E
authors.initials: RE
authors.lastname: Wegner
authors.forename: Kaan
authors.initials: K
authors.lastname: Oysul
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Pollock
authors.forename: Sait
authors.initials: S
authors.lastname: Sirin
authors.forename: Douglas
authors.initials: D
authors.lastname: Kondziolka
authors.forename: Ajay
authors.initials: A
authors.lastname: Niranjan
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
authors.forename: John C
authors.initials: JC
authors.lastname: Flickinger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019106:Postoperative Hemorrhage / Q000401:mortality; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000401:mortality; D011879:Radiotherapy Dosage; D016896:Treatment Outcome; D055815:Young Adult