[Hemorrhage after radiosurgery of cerebral arteriovenous malformations]

Obliteration is progressive after radiosurgery of cerebral arteriovenous malformations. Thus the hemorrhage risk still remains until obliteration. Purposes of this study are to appreciate severity of post-radiosurgery hemorrhages, actuarial risk of hemorrhage and parameters associated with it.

and method. Over 705 patients treated, 46 (6.5%) had one or several hemorrhages. Clinical, anatomic, dosimetric parameters and obliteration rates before hemorrhage were studied. Then, actuarial risks per patient and per hemorrhage were calculated. Correlations between parameters and risk were searched by uni and multivariate analysis by drawing hemorrhage-free survival curves (limit-product Kaplan-Meier) and Cox model.

Except one pure ventricular hemorrhage causing death of one patient, only parenchymal hemorrhages were associated with morbidity (80% of cases with 45% of permanent deficits). Overall mortality rate by hemorrhage was 6.5%. Overall morbidity rate was 34.8% and 13.6% for permanent deficit. Mean obliteration rate before hemorrhage was 25%. Actuarial hemorrhage rate were 2.98% per patient and 3.24% per hemorrhage. Actuarial rate per patient increased from 1.46% first year to 5.95% 4(th) year after radiosurgery. Parameters correlated with hemorrhage risk were in univariate analysis size (p=0.01), Spetzler and Martin's grade (p<0.001), dose to reference isodose (p=0.03), Dmin (p=0.08), intra or paranidal aneurysms (p<0.001), and recoverage (p<0.001). After multivariate analysis, only intra or paranidal aneurysms, recovering and Dmin were significantly associated with hemorrhage-free survival after RS.

Post-radiosurgery hemorrhages are often sum of hemorrhage risk factors of the cerebral arteriovenous malformation and factors predicting low rate of obliteration. They can be in some cases foreseen but rarely avoided.