title: Outcome after Gamma Knife surgery for intracranial arteriovenous malformations in children.
abstract: OBJECTIVE
  The focus of the present study was the evaluation of outcomes after unstaged and staged-volume Gamma Knife surgery (GKS) in children harboring intracranial arteriovenous malformations (AVMs).
  
  
  METHODS
  Twenty-two children (median age 9.5 years) underwent GKS for AVMs and were followed up for at least 2 years thereafter. The disease manifested with intracranial hemorrhage in 77% of cases. In 68% of patients the lesion affected eloquent brain structures. The volume of the nidus ranged from 0.1 to 6.7 cm(3). Gamma Knife surgery was guided mainly by data from dynamic contrast-enhanced CT scans, with preferential targeting of the junction between the nidus and draining vein. The total prescribed isodose volume was kept below 4.0 cm(3), and the median margin dose was 22 Gy (range 20-25 Gy). If the volume of the nidus was larger than 4.0 cm(3), a second radiosurgical session was planned for 3-4 years after the first one. Nine patients in the present series underwent unstaged radiosurgery, whereas staged-volume treatment was scheduled in 13 patients.
  
  
  RESULTS
  Complete obliteration of the AVM was noted in 17 (77%) of 22 patients within a median period of 47 months after the last radiosurgical session. Complete obliteration of the lesion occurred in 89% of patients after unstaged treatment and in 62.5% after staged GKS. Four (67%) of 6 high-grade AVMs were completely obliterated. Complications included 3 bleeding episodes, the appearance of a region of hyperintensity on T(2)-weighted MR images in 2 patients who had no symptoms, and reappearance of the nidus in the vicinity of the completely obliterated AVM in 1 patient.
  
  
  CONCLUSIONS
  Radiosurgery is a highly effective management option for intracranial AVMs in children. For larger lesions, staged GKS may be applied successfully. Initial targeting of the nidus adjacent to the draining vein and application of a sufficient radiation dose to a relatively small volume (≤ 4 cm(3)) provides a good balance between a high probability of obliteration and a low risk of treatment-related complications.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Tamura
authors.forename: Motohiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Mikhail
authors.initials: M
authors.lastname: Chernov
authors.forename: Manabu
authors.initials: M
authors.lastname: Tamura
authors.forename: Ayako
authors.initials: A
authors.lastname: Horiba
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Konishi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Muragaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iseki
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Okada
mesh_terms: D000293:Adolescent; D001921:Brain / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications / Q000601:surgery*; D020300:Intracranial Hemorrhages / Q000209:etiology; D008297:Male; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation*; D016896:Treatment Outcome