2005 Volume 33 Issue 5 Pages 347-351
Although stereotactic radiosurgery has been recognized as an effective treatment modality for cerebral arteriovenous malformations (AVMs), its long-term outcome after more than 10 years is still unknown. We retrospectively analyzed the complications arising long after radiosurgery for AVMs. Five-hundred patients with AVMs were treated with radiosurgery and were followed at the University of Tokyo hospital. The mean age was 31 years and the mean dose delivered to the AVM margin was 21.0 Gy. The mean diameter of AVMs was 1.9 cm. Radiation-induced neurological complications were observed in 5.2% of patients and could be reduced with recent improvements in imaging technique. Hemorrhage during the interval between radiosurgery and obliteration was observed in 23 out of 500 patients and after confirmation in 6 out of 250 patients. After radiosurgery, the risk of hemorrhage was decreased by 54% during the interval between radiosurgery and angiographic obliteration, and a small risk of hemorrhage remained even after obliteration. Delayed cysts developed in 3 out of 6 patients at the site of previous hemorrhage. The cyst spontaneously decreased in 1 patient and increased in another, requiring surgical resection. Delayed cyst formation unrelated to hemorrhage was also observed in 2 patients, which were closely observed.
Angiographic obliteration after radiosurgery for AVM is not necessarily equal to long-term cure because residual degenerated nidus might cause hemorrhage or delayed cyst formation. Radical treatments such as surgical excision of the nidus should be used for respectable lesions and cystoperitoneal shunt or placement of Ommaya reservoir should be selected for unresectable cystic lesions.
