Stereotactic radiosurgery for motor cortex region arteriovenous malformations

OBJECTIVE: The optimal management of arteriovenous malformations (AVMs) in critical brain locations remains controversial. To reduce the risk of an AV M hemorrhage and to enhance the possibility of preserving neurological func tion, stereotactic radiosurgery was performed in 33 patients with newly dia gnosed or residual AVMs located within the motor cortex. The role of emboli zation also was examined. METHODS: During a 9-year study period, 33 patients with AVMs located primar ily in the motor cortex region were treated with stereotactic radiosurgery. These patients were followed up radiographically for a minimum of 36 month s, or less if obliteration was documented before 36 months had elapsed. Of the 33 patients, 9 underwent embolization and 1 underwent microsurgery befo re radiosurgery. Nine patients required a second radiosurgery. The mean AVM target volume was 4.35 cc, and the average radiation dose to the AVM margi n was 20 Gy. The median follow-up was 36 months (range, 10-91 mo), and angi ographic follow-up of eligible patients was performed 24 or 36 months after radiosurgery. RESULTS: Results were stratified by radiosurgical target volumes: less than 3 cc (Group 1), 3 to 10 cc (Group 2), and greater than 10 cc (Group 3). Ov erall (including second radiosurgery), 23 (87%) of 15 patients in Group 1 h ad complete obliteration confirmed by angiography. Nine (64%) of 14 patient s in Group 2 exhibited nidus obliteration, and one (25%) of four patients i n Group 3 demonstrated obliteration on a magnetic resonance imaging scan. E ight patients (24%) underwent second-stage radiosurgery after angiography r evealed a persistent AVM nidus; three patients demonstrated complete oblite ration on follow-up angiography. The obliteration rate was higher (87%) for AVMs with less than 3 cc target Volume and lower (56%) for those with targ et volumes larger than 3 cc. One patient experienced worsening neurological function after radiosurgery, and one died from delayed AVM hemorrhage duri ng the latency period. No patient bled after angiographically confirmed AVM obliteration. CONCLUSION: Stereotactic radiosurgery is a successful and safe management o ption for patients with motor cortex AVMs. The obliteration of AVMs and the attendant low morbidity rates indicate a primary role for radiosurgery in these patients. Staged radiosurgery may be necessary to increase obliterati on rates for larger AVMs or for those that are not obliterated after the fi rst procedure.