Long-term Complications of Arteriovenous Malformation Treated by Gamma Knife Radiosurgery: A 10-Year Experience

Kang, Kwan Soo; Lim, Young Jin; Leem, Won; Rhee, Bong Arm; Kim, Gook Ki; Kim, Tae Sung

Abstract

OBJECTIVE
The authors conduct a retrospective study to analyze long-term complications of Gamma knife radiosurgery for cerebral arteriovenous malformation(AVM).
METHODS
We performed a detailed long-term follow-up study of 100 patients, who could be followed more than 2 years, with AVMs treated by Gamma knife radiosurgery during the last 10 years. At the time of radiosurgery, the mean age was 31.6 years(range : 7-65). The mean follow-up period after radiosurgery was 63.7 months(range : 24-116) except one mortality related with rebleeding. Mean target volume was 5039.2mm3(range : 105-38400). In all of the patients, AVMs were completely covered with a 40-80% isodose profile. The selected target dose delivered by the Gamma Knife was 7.2 to 33 Gy(mean : 22.2 Gy) at the periphery.
RESULTS
Angiographic complete obliteration rate was 80% at 2 years after radiosurgery. Rebleeding occur in 4 cases at 4, 8, 44, 98 months after radiosurgery, respectively. Annual bleeding rate was 0.6%. Among them, one patient died. Postradiosurgical complications consisted of adverse radiation effects (ARE) in 19 patients, cyst formation in three, and asymptomatic vascular stenosis in one. Symptomatic ARE was 8% and the mean time from the last radiosurgery to ARE was 12.4 months(1-29) on follow-up images. Three patients, who have been verified angiographically complete obliteration, developed cyst formation within previous irradiated area at 48, 102, 115 months after radiosurgery respectively. Two of them underwent cystic aspiration with catheter drainage.
CONCLUSION
The individual incidence of postradiosurgical complication was approximately from 3 to 19%, which is higher than expected. Long-term follow-up is mandatory even after complete nidus obliteration.