Arteriovenous malformations after Leksell gamma knife radiosurgery: rate of obliteration and complications.

OBJECTIVE Although relevant information exists regarding the chance of obliterating arteriovenous malformations (AVMs) using radiosurgery, the overall chance of cure after gamma knife radiosurgery is usually only extrapolated from a portion of all monitored patients. This chance and the risks involved in radiosurgery, including repeat treatment when necessary in a defined population of treated patients, were analyzed in our study. METHODS Between October 1992 and June 2000, gamma knife radiosurgery was performed on 330 patients with AVMs. The volume of the AVM nidus ranged from 0.15 to 28.6 cm (median, 3.9 cm). When complete obliteration was not achieved within 3 years, repeat radiosurgery was performed on 76 patients. The volume of the nidus for the second treatment ranged from 0.09 to 16.8 cm (median 2.9 cm). The result was reviewed in 300 (91%) patients after the first round of treatment and in 68 (89.5%) after the second round of treatment. RESULTS AVM obliteration was achieved in 222 (74%) patients after the first round of radiosurgery and in 47 (69%) after the second. The overall chance of cure was 92% (269 patients). Final angiography verified complete obliteration by 12 to 96 months (median, 25 mo) after initial radiosurgery. Smaller volume AVMs and the application of a higher radiation dose resulted in a higher chance of obliteration. The risk of rebleeding after radiosurgery was 2.1% annually until full obliteration, and the overall mortality from rebleeding was 1%. The risk of permanent morbidity after the first and second radiosurgery treatments were 2.7 and 2.9%, respectively. The cumulative risk of morbidity in both groups of patients was 3.4%. CONCLUSION Although one-quarter of the patients required that the treatment be repeated, gamma knife radiosurgery can offer a high cure rate for patients treated for AVMs with a low risk of morbidity and mortality from rebleeding during the latent period.