title: Outcome of cerebral arteriovenous malformations after linear accelerator reirradiation.
abstract: BACKGROUND
  The aim of this study was to evaluate the clinical outcome of patients undergoing single-dose reirradiation using the Linear Accelerator (LINAC) for brain arteriovenous malformations (AVM).
  
  
  METHODS
  A retrospective study of 37 patients with brain AVM undergoing LINAC reirradiation between April 2003 and November 2011 was carried out. Patient characteristics, for example, gender, age, use of medications, and comorbidities; disease characteristics, for example, Spetzler-Martin grading system, location, volume, modified Pollock-Flickinger score; and treatment characteristics, for example, embolization, prescription dose, radiation dose-volume curves, and conformity index were analyzed. During the follow-up period, imaging studies were performed to evaluate changes after treatment and AVM cure. Complications, such as edema, rupture of the blood-brain barrier, and radionecrosis were classified as symptomatic and asymptomatic.
  
  
  RESULTS
  Twenty-seven patients underwent angiogram after reirradiation and the percentage of angiographic occlusion was 55.5%. In three patients without obliteration, AVM shrinkage made it possible to perform surgical resection with a 2/3 cure rate. A reduction in AVM nidus volume greater than 50% after the first procedure was shown to be the most important predictor of obliteration. Another factor associated with AVM cure was a prescription dose higher than 15.5 Gy in the first radiosurgery. Two patients had permanent neurologic deficits. Factors correlated with complications were the prescription dose and maximum dose in the first procedure.
  
  
  CONCLUSIONS
  This study suggests that single-dose reirradiation is safe and feasible in partially occluded AVM. Reirradiation may not benefit candidates whose prescribed dose was lower than 15.5 Gy in the first procedure and initial AVM nidus volume did not decrease by more than 50% before reirradiation.
authors.affiliation: Serviço de Radioterapia do Hospital São Joaquim - Beneficência Portuguesa de São Paulo and Universidade Federal de São Paulo/Escola Paulista de Medicina - UNIFESP/EPM, São Paulo, S.P., Brazil.
authors.forename: Paulo L
authors.initials: PL
authors.lastname: Moraes
authors.affiliation: Universidade Federal de São Paulo/Escola Paulista de Medicina - UNIFESP/EPM, São Paulo, S.P., Brazil.
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: Dias
authors.affiliation: Hospital Israelita Albert Einstein, and Faculdade de Medicina da Universidade de São Paulo, São Paulo, S.P., Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Weltman
authors.affiliation: Universidade Federal de São Paulo/Escola Paulista de Medicina - UNIFESP/EPM, São Paulo, S.P., Brazil.
authors.forename: Adelmo J
authors.initials: AJ
authors.lastname: Giordani
authors.affiliation: Serviço de Radioterapia e Radiocirurgia do Hospital Bandeirantes, São Paulo, S.P., Brazil.
authors.forename: Salomon
authors.initials: S
authors.lastname: Benabou
authors.affiliation: Universidade Federal de São Paulo/Escola Paulista de Medicina - UNIFESP/EPM, São Paulo, S.P., Brazil.
authors.forename: Helena R C
authors.initials: HR
authors.lastname: Segreto
authors.affiliation: Universidade Federal de São Paulo/Escola Paulista de Medicina - UNIFESP/EPM, São Paulo, S.P., Brazil.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Segreto
keywords: Arteriovenous malformations; radiosurgery; reirradiation