title: Early draining vein occlusion after gamma knife surgery for arteriovenous malformations.
abstract: BACKGROUND
  Increased signals on T2-weighted magnetic resonance imaging usually interpreted as radiation-induced changes or brain edema is a common short- to mid-term complication after Gamma Knife surgery (GKS) for intracranial arteriovenous malformations (AVMs), although its nature remains to be clarified. Early draining vein occlusion with resultant brain edema or hemorrhage, although well established in surgical series, was not described in radiosurgical literature until recently.
  
  
  OBJECTIVE
  To outline the incidence, clinical manifestations, and outcomes of this unusual complication in our series of 1256 AVM patients treated with GKS.
  
  
  METHODS
  From 1989 to 2008, 1400 patients underwent GKS for cerebral AVMs or dural arteriovenous fistulae at the University of Virginia. In 1256 patients, magnetic resonance imaging after GKS was available for analysis of radiation-induced changes and early draining vein occlusion.
  
  
  RESULTS
  After GKS, 456 patients (36%) developed radiation-induced changes surrounding the treated nidi. Among these patients, 12 had early thrombosis of the draining vein accompanied by radiation-induced changes. Venous thrombosis occurred 6 to 25 months (median 11.6 months) after GKS. Three patients were asymptomatic on the image findings of venous occlusion and brain edema, 3 experienced headache, 1 had seizure and headache, and neurological deficits developed in 5. Patients with neurological deficits were treated with corticosteroids; 2 of the patients recovered completely, 1 still had slight hemiparesis, 1 had short-term memory deficits, and 1 died of massive intracerebral hemorrhage.
  
  
  CONCLUSIONS
  Although venous structures are considered more radioresistant, endothelial damage accompanied by venous flow stasis might cause early venous thrombosis and premature venous occlusion after radiosurgery for AVMs. In our series, all patients had a favorable outcome except 1 with a fatal hemorrhage.
authors.affiliation: Lars Leksell Center for Gamma Surgery, Department of Neurosurgical Surgery, University of Virginia Health Sciences Center, Charlottesville, Virginia, USA.
authors.forename: Chun-Po
authors.initials: CP
authors.lastname: Yen
authors.forename: Mohamad A
authors.initials: MA
authors.lastname: Khaled
authors.forename: Lucia
authors.initials: L
authors.lastname: Schwyzer
authors.forename: Matjaz
authors.initials: M
authors.lastname: Vorsic
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Dumont
authors.forename: Ladislau
authors.initials: L
authors.lastname: Steiner
mesh_terms: D000328:Adult; D000368:Aged; D001164:Arteriovenous Fistula / Q000453:epidemiology* / Q000601:surgery*; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D002538:Intracranial Arteriovenous Malformations / Q000453:epidemiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D016634:Radiosurgery / Q000706:statistics & numerical data*; D018570:Risk Assessment; D012307:Risk Factors; D020246:Venous Thrombosis / Q000453:epidemiology*; D014768:Virginia / Q000453:epidemiology