LINAC RADIOSURGERY FOR THE TREATMENT OF 8 4 ARTERIOVENOUS-MALFORMATIONS

We have treated in 1990 and 1991, 84 arteriovenous malformations (AVMs ) by radiosurgery. Irradiation was realized by 5 to 7 arcs with 15 MVX rays circular minibeams of a GE-CGR Saturne 43 Linac diameter, at 100 cm 6 to 20 mm; the Betti arm chair and the Talairach frame. The presc ribed peripheral dose containing the nidus was 25 Gy corresponding to the 60-70% isodose range (100% was the maximum dose). For the irradiat ion planning we used the 'associated targets methodology' and the ARTE MIS-3D TPS, both of which have been developped in the radiotherapy dep artement of the Tenon hospital. Evaluation was performed in February 1 995, the follow-up range was 38 to 62 months In 1990, 46 cases were tr eated for cure and were all evaluable, whereas in 1991, among the 38 i rradiated cases one patient was not evaluable because of lack of arter iographic control. Thus this series consisted in 84 evaluable cases. T he overall obliteration rate was 65/84 (78%), partial obliteration was seen in 18/84(21%) and no change in 1 case. According to AVM volume, obliteration rate was 42/47 (89%); whereas it was 23/37 (63%) in multi -osocenters treatments. The obliteration rate was better for not previ ously treated cases: 39/44 (89%) than for previously treated nidus (mo stly embolisation)65% (26/40). In 23 spheroid AVMs obliteration rate w as 87% (20/23) in 43 ellipsoid AVMs the obliteration rate was 77% (33/ 43); and in irregular rounded nidus, it was 67% (12/18). The periphera l dose of 25 Gys has been used in 78 cases (93%), the obliteration rat e was 63/78 (81%); in 6 other cases treated with 15-23.5 Gy, it was 2/ 6 (33%). We observed two recurrences of haemorrhage at 4 and 6 months after radiosurgery (recurrent haemorrhage rate 2/84 = 2.4%) with total neurological recovery in one of the two patients. One died of myocard ial infarctus 11 months after radiosurgery (there was a partial oblite ration of his AVM at 8 months after radiosurgery). There was no AVM re lated death. One patient developed an epilepsy.