Management and prognosis of cysts developed on long-term follow-up after Gamma Knife radiosurgery for intracranial arteriovenous malformations.
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.
Izawa
Masahiro
M
Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo 162-8666, Japan. mizawa@nij.twmu.ac.jp
Chernov
Mikhail
M
Hayashi
Motohiro
M
Nakaya
Kotaro
K
Kamikawa
Shuji
S
Kato
Koichi
K
Higa
Takashi
T
Ujiie
Hiroshi
H
Kasuya
Hidetoshi
H
Kawamata
Takakazu
T
Okada
Yoshikazu
Y
Kubo
Osami
O
Iseki
Hiroshi
H
Hori
Tomokatsu
T
Takakura
Kintomo
K
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