Radiosurgery of choroidal and cisternal cerebral arteriovenous malformations

Purpose. Cerebral arteriovenous malformations surrounded by cerebrospinal f luid seemed to exhibit worse response to radiosurgery than others. We searc hed to verify if this is was true and to find causes. Material and methods. From our series of 705 patients with cerebral arterio venous malformations treated by radiosurgery, 3,8 % (27/705) had choroidal or cisternal arteriovenous malformations. Revelation mode was hemorrhage in 86 % of cases but sometimes headaches occurred before hemorrhage; thus ove rall hemorrhage rate was 96 %. Mean age of revelation was 24. Mean size was 20 mm, mean volume was 4 cc. Spetzler & Martin's grades were 35 % in grade II, 43 % in grade III and 22 % in grade IV. Location was ventricular in 63 % of cases and cisternal in 37 %. Mean dose at reference isodose was 24 Gy with a higher rate of monoisocenters. We looked for differences between th is population of arteriovenous malformations and the rest of the series for patients, treatments prior radiosurgery, cerebral arteriovenous malformati ons's characteristics, dosimetric parameters and complications. Statistical analysis was done with a Pearson chi2 test and Spearman non parametric cor relation test. Results. Obiteration rate was 47.6 % with a mean delay of 26 months. Differ ential characteristics of choroidal or cisternal arteriovenous malformation s were: younger age of revelation, higher frequency of hemorrhage, of intra or paranidal aneurysms, of deep unique drainage, a higher Spetzler grade a nd a smaller rate of complete recovering.