Radiosurgical retreatment for brain arteriovenous malformation.

OBJECTIVE To analyze our experience with a second radiosurgical treatment for brain arteriovenous malformations (BAVMs) after an unsuccessful first radiosurgical treatment. METHODS Between 1993 and 2000, 242 patients were treated by the Toronto Sunnybrook Regional Cancer Center using a LINAC system. Fifteen of these patients required a second radiosurgical intervention due to the failure of the first procedure. Data was collected on baseline patient characteristics, BAVM features, radiosurgery treatment plan and outcomes. Brain arteriovenous malformation obliteration was determined by follow-up MRI and angiography and the obliteration prediction index (OPI) calculated according to a previously established formula. RESULTS The median interval between the first and second treatment was 46 months (range 39-109). The median follow-up after the second procedure was 39 months (range 26 to 72). The mean BAVM volume before the first treatment was 8.9cm3 (range 0.3-21) and before the second treatment was 3.6cm3 (range 0.2-11.6). The mean marginal dose during the first treatment was 18Gy (range 12-25) and during the second treatment was 16Gy (range 12-20). After the second treatment, nine patients had obliteration of their BAVM confirmed by angiography and one patient had obliteration confirmed by MRI, resulting in an obliteration rate of 66.6%, which is very comparable to that predicted by the OPI (65%). After the second treatment two patients had a radiation-induced complication (13.3%). CONCLUSION Retreatment of BAVM using a second radiosurgery procedure is a safe and effective option that offers the same rate of success as the initial radiosurgery and an acceptable risk of radiation-induced complication.