title: Radiation-related adverse effects observed on neuro-imaging several years after radiosurgery for cerebral arteriovenous malformations.
abstract: BACKGROUND
  To our knowledge, there are no reported arteriovenous malformation (AVM) series in which detailed long-term follow-up results after radiosurgery were described based on the whole patient group.
  
  
  METHODS
  We performed a detailed long-term follow-up study of 53 patients with cerebral AVMs treated with gamma knife (GK) radiosurgery, with emphasis on radiation-related adverse effects detected on neuro-imaging after a long post-irradiation latency period (3-10 years). The post-GK follow-up period was 40-232 months excluding two mortalities, the mean being 112 and the median being 111 months.
  
  
  RESULTS
  Three patients (5.6%) have, as yet, refused all neuro-imaging follow-up studies. Complete nidus obliteration was confirmed angiographically in 32 patients (60.4%) between 1 and 5 post-GK years. In the other 18 patients (34%), despite significant nidus shrinkage being angiographically demonstrated, complete obliteration was not achieved during a 2-7 year follow-up period. There were two mortalities, one AVM-related (massive re-bleeding during the latency period) and the other angiography-related. There were five radiation-related morbidities (9.4%), three of which-hemi-Parkinson syndrome, hemiparesis, and visual field disturbances attributable to delayed cyst formation-manifested at 5.5, 7 and 7 post-GK years, respectively. We also experienced five patients (9.4%) in whom, despite remaining asymptomatic to date, radiation-related adverse effects were seen on neuro-imaging: middle cerebral artery stenosis at 3 post-GK years in one patient; dural arteriovenous fistula at 7 post GK-years in one; delayed cyst formation in two, at 5 and 10 post-GK years; and a small cavitation at 9 post-GK years.
  
  
  CONCLUSIONS
  Long-term follow-up, particularly with neuro-imaging modalities, is essential even after the "treatment goal" has been attained.
authors.affiliation: Department of Neurosurgery, Tokyo Women's Medical College Dai-ni Hospital, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: M
authors.initials: M
authors.lastname: Hara
authors.forename: M
authors.initials: M
authors.lastname: Ide
authors.forename: Y
authors.initials: Y
authors.lastname: Ono
authors.forename: M
authors.initials: M
authors.lastname: Jimbo
authors.forename: I
authors.initials: I
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology / Q000528:radiation effects*; D001927:Brain Diseases / Q000209:etiology* / Q000473:pathology; D002533:Cerebral Angiography; D002648:Child; D003560:Cysts / Q000209:etiology* / Q000473:pathology; D005260:Female; D005720:Gamma Rays; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D002542:Intracranial Embolism and Thrombosis / Q000209:etiology* / Q000473:pathology; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods