title: Management and prognosis of cysts developed on long-term follow-up after Gamma Knife radiosurgery for intracranial arteriovenous malformations.
abstract: BACKGROUND
  Delayed cyst formation is a well-recognized complication after radiosurgery for intracranial AVM. The objective of the present study was the evaluation of the different management options for these lesions and the corresponding prognosis of patients.
  
  
  METHODS
  Between 2000 and 2005, 12 patients with intracranial AVM initially treated by GKR were reevaluated at Tokyo Women's Medical University because of delayed cyst formation in the vicinity of the target area. There were 7 men and 5 women. The mean age of the patients was 31.8 years at the time of GKR and 41.1 years at the time of complication. The average period between treatment and diagnosis of the complication constituted 6.7 years. All AVMs had lobar location and showed complete angiographic obliteration after GKR.
  
  
  RESULTS
  The most common neurological signs and symptoms at the time of cyst presentation were headache (10 cases) and seizures (4 cases). Two patients were asymptomatic. Three patients underwent surgery soon after the diagnosis of the cyst, whereas initial observation was done in another 9. Among the latter, 5 patients had to be treated surgically thereafter because of persistent or aggravated neurological symptoms associated with radiological cyst expansion. Four other patients, including both asymptomatic ones, are in stable condition without surgery. Follow-up after treatment of the cyst varied from 7 to 60 months (average, 34.3 months). All patients are in good condition.
  
  
  CONCLUSIONS
  Although delayed formation of cysts after GKR for intracranial AVM should be considered as a complication of the radiosurgical treatment, it has a relatively good prognosis. Observation can be recommended as initial option for compensated and asymptomatic patients.
authors: Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo 162-8666, Japan. mizawa@nij.twmu.ac.jp
authors: Masahiro
authors: M
authors: Izawa
authors: Mikhail
authors: M
authors: Chernov
authors: Motohiro
authors: M
authors: Hayashi
authors: Kotaro
authors: K
authors: Nakaya
authors: Shuji
authors: S
authors: Kamikawa
authors: Koichi
authors: K
authors: Kato
authors: Takashi
authors: T
authors: Higa
authors: Hiroshi
authors: H
authors: Ujiie
authors: Hidetoshi
authors: H
authors: Kasuya
authors: Takakazu
authors: T
authors: Kawamata
authors: Yoshikazu
authors: Y
authors: Okada
authors: Osami
authors: O
authors: Kubo
authors: Hiroshi
authors: H
authors: Iseki
authors: Tomokatsu
authors: T
authors: Hori
authors: Kintomo
authors: K
authors: Takakura
mesh_terms: D000328:Adult; D000465:Algorithms; D003560:Cysts / Q000209:etiology* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006261:Headache / Q000209:etiology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D011183:Postoperative Complications / Q000601:surgery*; D011379:Prognosis; D016634:Radiosurgery / Q000009:adverse effects*; D012640:Seizures / Q000209:etiology; D016896:Treatment Outcome