Treatment outcome after linac-based radiosurgery in cerebral arteriovenous malformations: retrospective analysis of factors affecting obliteration.

Objective: We investigated patient outcome and factors affecting obliteration rate after radiosurgery in cerebral arteriovenous malformations (AVM).

Methods: We have treated 110 patients with cerebral AVM with linac-based radiosurgery (RS). AVM classification according Spetzler-Martin was 17 patients grade I (15%), 39 grade II (36%), 41 grade III (37%), 12 grade IV (11%) and 1 grade V (1%). Median single dose was 18 Gy. Mean treatment volume was 4.7 cc (range, 0.1-24.0 cc). Fifty-two patients experienced hemorrhage prior to RS. Median follow-up was 2.5 years.

Results: Actuarial complete obliteration rate (CO) was 51% after 3 years and 67% after 4 years. CO rate was significantly higher in AVM <3 cm (64% vs. 43%, P<0.04) and in patients with grade I/II vs. III-V (71% vs. 33%, P<0.001). CO was significantly improved after doses >18 Gy (P<0.02) and in male gender (P<0.04). In multivariate analysis Spetzler-Martin grade remained significant. Intracranial hemorrhage after RS occurred in 9 patients 13.9 months median after RS. Neurological dysfunction improved/completely dissolved or remained stable in 95% of patients. No new onset of neurological dysfunction was seen. No significant adverse effects after RS were seen.

Conclusions: The rate of obliteration after RS in AVM depends on applied single dose as well as size and Spetzler-Martin grade. RS is an alternative to neurosurgery, especially in patients with small or surgically inaccesible AVM.