Gamma Knife Radiosurgery: A Definitive Treatment for Secondary Angiogenesis in Vein of Galen Aneurysmal Malformations

Introduction: Vein of Galen Aneurysmal Malformations (VGAMs) are life-threatening, rare, congenital vascular lesions that occur due to embryological remnant arterial feeders draining into the immature midline prosencephalic veins. We report a 15-year-old male with incidental discovery of a mural VGAM after reporting “popping” sensations. Angiographic and echocardiogram studies revealed an aneurysmal dilation measuring 3.8cm x 3.8cm x 2.4cm supplied by the internal carotid artery, posterior communicating artery, anterior cerebral and pericallosal arteries, parietal branch of the superficial temporal artery, and the posterior branch of the middle meningeal artery. The latter two vessels comprised a transdural peri-Galenic network feeding into the VGAM. Two embolization sessions were conducted with successful obliteration of ICA branches using a total of seven hydrocoil implants, but subsequent MRI revealed VGAM persistence, measuring 4.3cm x 2.4cm x 1.9cm. Subsequent Gamma Knife Radiosurgery (GKRS) successfully obliterated the transdural supply. 10 months post-GKRS, MRI/MRA/MRV revealed an angiographic cure of the lesion. The patient is currently an asymptomatic and healthy 18-year-old.

Methods: Online searches were performed using PubMed and Wiley Online Library. The analysis consisted of 70 peer-reviewed publications, published from 1969 to 2022.

Results: We define the "secondary angiogenesis" phenomenon as VGAM cases with a discrete contribution from ECA/transdural vessels or cases that form novel, distinct feeders in reaction to first-line embolization treatment. In our meta-analysis, we describe 7 previously published cases with secondary angiogenesis. Of these, 4 of which were definitively treated with GKRS. We compare the 100% success rate of GKRS in the treatment of VGAMs with secondary angiogenesis (n=5) to all previously published cases of all VGAMs (n=30).

Conclusion : Our case and similar ones reported in the existing literature show the promise of GKRS as a definitive treatment of VGAMs that are refractory to first-line treatment methods due to a secondary angiogenesis phenomenon.