title: Outcomes of surgery for resection of regions of symptomatic radiation injury after stereotactic radiosurgery for arteriovenous malformations.
abstract: OBJECTIVE
  Although radiation injury after stereotactic radiosurgery (SRS), including radiation necrosis (RN), is often treated with surgical resection, detailed outcome data are lacking after resection of symptomatic radiation-injured regions with imaging characteristics suspicious for RN after SRS for arteriovenous malformations (AVM). We present outcomes in seven such patients.
  
  
  METHODS
  We conducted a retrospective chart review of seven patients with AVMs of Spetzler-Martin Grades II (n = 1), III (n = 2), and IV (n = 4) who underwent helium ion, proton beam, or gamma knife SRS and required resection of RN-suspicious tissue 1 to 24 months after post-SRS symptom onset. Postoperative outcomes included Karnofsky Performance Scale (KPS) score and time to symptomatic improvement.
  
  
  RESULTS
  Symptomatic improvement required at least 9 months in the three patients with large regions suspicious for RN (>or=4 cm), whereas of four patients with smaller regions (<4 cm), three showed improvement within 2 months (P < 0.05). The remaining patient, who showed no benefit, underwent resection 2 years after the onset of RN symptoms (compared with <or= 8 mo for the other six patients). Surgery improved KPS scores in four patients with a preoperative KPS score of 50 or lower, but not in three patients with preoperative KPS scores greater than 70 (P < 0.05). Outcomes were not consistently associated with AVM size or location, SRS treatment volume or dose, associated aneurysm, or residual AVM.
  
  
  CONCLUSIONS
  After SRS for AVMs, resection of symptomatic RN-suspicious tissue areas is beneficial in reversing neurological deficits and improving KPS scores in selected patients. Times to improvement were longer when larger areas were resected. Delaying such surgery after symptom onset may negatively affect improvement.
authors.affiliation: Department of Neurosurgery Stanford University, Stanford, California 94305, USA.
authors.forename: Justin L
authors.initials: JL
authors.lastname: Massengale
authors.forename: Richard P
authors.initials: RP
authors.lastname: Levy
authors.forename: Mary
authors.initials: M
authors.lastname: Marcellus
authors.forename: Gregory
authors.initials: G
authors.lastname: Moes
authors.forename: Michael P
authors.initials: MP
authors.lastname: Marks
authors.forename: Gary K
authors.initials: GK
authors.lastname: Steinberg
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies; D016896:Treatment Outcome