MATERIAL and METHODS: A total of 86 patients’ clinical outcomes were fully collected. Modalities and complications of the procedure were analyzed as well as the clinical and anatomic outcomes. Risk factors associated with hemorrhage were determined by multivariate analysis.

RESULTS: The mean duration of radiological and clinical follow-up was 42 months (12.3-82.5 months) and 57.6 months (12.3-108.9 months), respectively. The total annual hemorrhage rate was 1.66% with 2.26% for ruptured AVMs and 1.08% for unruptured AVMs. The annual mortality rate was 0.4%. The total obliteration rate was 28.2% at follow-up. Clinical deterioration occurred in 4 patients (4.7%). Volume larger than 22 ml, diameter prior GKS larger than 3.5 cm and margin dose less than 16 Gy significantly increased the hemorrhage risk.

CONCLUSION: The post-treatment hemorrhage could be predictable based on AVM’s characteristics and treatment approaches. The annual hemorrhage rate was low for both ruptured and unruptured AVMs after combined treatment; however, the total obliteration rate was low. Long-term follow-up and larger population are needed for evaluating the clinical effect for this combined treatment. Keywords : Cerebral arteriovenous malformations, Onyx, Embolization, Gamma knife surgery