Gamma Knife Radiosurgery for Berry Aneurysms: Quo Vadis

Intracranial aneurysms are vascular malformations with significant mortality and morbidity profile. Various treatment modalities have been developed to positively impact the outcome profile with gradual shift to the minimally invasive treatment modalities. Gamma knife radiosurgery (GKRS) is an established primary treatment modality for various intracranial arteriovenous malformations (AVMs); however, its efficacy for berry aneurysmal obliteration has been historically dismal. The aim of this study is to evaluate the factors responsible for poor radio surgical outcome for intracranial aneurysms. The literature is reviewed for the differential efficacy of GKRS for aneurysm and AVM. Though both are vascular malformations, aneurysm and AVM have inherent differences in angioarchitecture, intracranial location, surrounding neighborhood, radio-sensitivity, and latency for obliteration. The major difference arises because of surrounding neighborhood of connective tissue stroma which stabilizes the irradiated pathology. Though considered radioresistant, aneurysms show promising results with animal models of radiosurgery. The future lies in two hypothetical improvements: with a supporting neighborhood or sensitization of the vessel wall that may change the natural history of an aneurysm, especially an unruptured one.