Clinical outcome and complications of gamma knife radiosurgery for intracranial arteriovenous malformations.

We sought to evaluate the outcome of intracranial arteriovenous malformation (AVM) treated with gamma knife radiosurgery (GKRS) (Elekta, Stockholm, Sweden) as a primary treatment as well as an adjunct therapy. GKRS has emerged as an important treatment option for intracranial AVM. However, the long term outcome of GKRS on AVM is not well understood. We performed a retrospective review of 85 patients with AVM from 2000-2012 who received GKRS. Out of 85 patients, 13 had undergone prior embolization. The study population was monitored clinically and radiographically after GKRS treatment. Outcome following GKRS for intracranial AVM showed significant variations in nidus obliteration (obliteration in 67 [79%] patients and increase of nidus size on MRI in 18 [21%] patients). The median time to nidus obliteration was 31 months. Overall two (2.3%) patients had intracranial bleeding and the annual bleeding risk was 1.6% after GKRS. Predictive factors for obliteration of the nidus in patients with AVM were low AVM score, Spetzler-Martin grade I-III and female sex. Seventeen (20%) and one (1.17%) patients underwent repeat GKRS and resection, respectively, after initial GKRS, due to increased size of the nidus and GKRS related cyst formation. Thus, GKRS offers a high obliteration rate of AVM, low risk of intracranial bleeding and neurological morbidity, both as primary modality and as an adjunctive treatment. Therefore, GKRS is an effective treatment option for new patients with AVM as well as an adjuvant therapy in patients with recurrent AVM.