Treatment of cerebral Arteriovenous Malformations with radiosurgery or hypofractionated stereotactic radiotherapy in a consecutive pooled LINAC series

Abstract Objective To review outcomes after LINAC stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (hfSRT) of arteriovenous malformations (AVM) from a consecutive and pooled series of two Novalis® centers and to analyse influence of AVM size, Spetzler-Martin (SM) grade, pre-treatment, and hemorrhagic vs. non-hemorrhagic presentation. A subgroup analysis of ARUBA eligible patients was additionally performed. Methods Prospectively collected treatment and outcome data were supplemented by retrospectively collected follow-up (FU) data for 93.8% of all patients (pts). A total of 129 pts with AVM had SRS or hfSRT between 2000 and 2014 with the same LINAC system in two centers. Data analysis included initial presentation, SM grade, occlusion rates assessed by MR- and/or digital subtraction angiography (DSA), neurological and therapeutical complications, and pre-treatments. Statistical analysis was performed for pts’ demographic data and for factors potentially influencing outcome. Results Initial presentation was haemorrhage in 43.8% or seizures/neurological deficits in 46.2%. The series included 6 SM grade I (5%), 26 SM II (21.5%), 55 SM III (45.5%), 28 SM IV (23%) and 6 SM V cases (5%). Pre-embolization was used in 36 pts (29.8%), 8 pts had prior surgery (6.6%) and 6 pts were irradiated before elsewere (5%); 5 pts (4.2%) received multimodal pre-treatment. Mean FU was 43 months. The occlusion rate for the total series was 71.1%, for SM I/II cases 80.6% and 67.4% for the SM >III subgroup. The occlusion rate was 75.0% for the small volume (< 4 cc) and 55.6% for the large volume (>10 cc) subgroup. There was no statistical difference between the occlusion rate of pts with or w/o pre-treatments if taken all modalities together (72.7% and 69.7%, respectively). There was only a trend of a belated occlusion of pre-embolized AVMs. The occlusion rate for hemorrhagic AVM was with 77.4% better than for non-hemorrhagic (66.2%) or ARUBA eligible AVM (64.8%) but without reaching statistical significance. Neurological deterioration was seen in 13.2% of the pts. There were 2 re-bleedings within 17-18 months (1.7%), one of them w/o a new neurological deficit and total occlusion after re-RS. One patient with pre-existing epilepsy died a sudden unexpected death (mortality rate: 0.8%). Conclusions Overall SRS and hfSRT are valuable therapy options esp. in symptomatic AVM pts with a low rate of morbidity and mortality and an acceptable overall complete o