title: Evaluation of prognostic factors as predictor of AVMS obliteration after Gamma Knife radiosurgery.
abstract: BACKGROUND
  The reported AVMs obliteration rate after Gamma Knife radiosurgery (GKS) ranges from 70 to 94 %. The objective of the present study was to assess prognostic factors predictive for cerebral AVMs obliteration in 127 patients who underwent GKS.
  
  
  METHODS
  The AVMs were classified according to the Spetzler-Martin classification. Twenty-one cases (16.5 %) were classified as grade I, 46 cases (36.2 %) as grade II, 51 cases (40.1 %) as grade III, and nine cases (7.1 %) as grade IV-V. The AVMs were deeply located in 16.5 % of patients. The peripheral prescription dose ranged from 16 to 30 Gy (mean 22.3 Gy). The AVMs volume ranged from 0.1 to 13 cc (mean 2.7 cc).
  
  
  RESULTS
  In 72 patients out of the 104 (69.2 %) with a radiological follow-up, MRI showed the AVM obliteration; in 54 cases (60 %) out of the 90 that performed a DSA, a complete AVM obliteration was achieved (average closure time 48.5 months). The volume of the nidus (p = 0.001), the prescription dose (p = 0.004), the 2002 Pollock-Flickinger classification (p = 0.031), and their 2008 revised classification (p = 0.025) were found to be statistically significant in predicting the probability of AVM closure. In the multivariate analysis, only the prescription dose was found to be an independent prognostic factor (p = 0.009) for AVM obliteration.
  
  
  CONCLUSIONS
  The volume of the nidus and the prescription dose significantly influence the outcome of radiosurgical treatment. The Pollock-Flickinger classification was found to be a reliable scoring system in predicting the AVM closure and an important tool for selection of patients candidate for GKS.
authors: Department of Neurosurgery and Gamma Knife Radiosurgery, San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20132, Milan, Italy. franzin.alberto@hsr.it
authors: Alberto
authors: A
authors: Franzin
authors: Silvia
authors: S
authors: Snider
authors: Nicola
authors: N
authors: Boari
authors: Francesco
authors: F
authors: Scomazzoni
authors: Piero
authors: P
authors: Picozzi
authors: Giorgio
authors: G
authors: Spatola
authors: Filippo
authors: F
authors: Gagliardi
authors: Pietro
authors: P
authors: Mortini
mesh_terms: D000328:Adult; D002533:Cerebral Angiography / Q000379:methods; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000145:classification / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016634:Radiosurgery / Q000379:methods*