LINEAR-ACCELERATOR RADIOSURGERY OF CEREBRAL ARTERIOVENOUS-MALFORMATIONS - AN UPDATE

ONE HUNDRED EIGHTY patients affected by cerebral arteriovenous malform ations (AVMs) underwent radiosurgical treatment in our department. One hundred fifty-three patients have been treated with complete irradiat ion of the entire AVM nidus. In 27 patients (with large and/or three-d imensional irregular target volumes), only part of the nidus was cover ed with a dose adequate for obliteration. Follow-up ranged from 88 to 1 months (mean, 43.1 mo). Angiographic control was performed at 12, 24 , and 36 months until complete obliteration was attained. The complete obliteration rate was 46% at 1 year and 80% at 2 years. We observed 1 5 hemorrhages after treatment, and five patients died from them. No bl eeding took place after complete angiographic obliteration. The aim of this study is to evaluate the effect of irradiation on bleeding risk after radiosurgery and before complete obliteration. Inclusive paramet ers of patients considered at risk were as follows: 1) all patients in the time lapse between irradiation and demonstrated complete angiogra phic obliteration; 2) all patients in the time lapse between irradiati on and definitive treatment either by surgery or embolization; and 3) all patients in the time lapse between irradiation and death. These gr oups include all irradiated patients who still had incompletely oblite rated AVMs. They were stratified starting from 0 time (the date of rad iosurgery), and the hemorrhages were evaluated every 6 months. In tota lly irradiated cases, the bleeding risk decreased from 4.8% in the fir st 6 months after radiosurgery to 0% starting from the 12th month of t he follow-up. In partially irradiated cases, the bleeding risk increas ed from 4% in the first 6 months to 12 to 10% from the 6th to the 18th month and decreased to 5.5% from the 18th to the 24th month; no bleed ing was observed after the 24th month.