Peculiar Characteristics of Arteriovenous Malformations Arising in the Galenic Region.

Arteriovenous malformations (AVM) are congenital vascular lesions fed by arterial feeders originating from branches of the internal carotid artery (ICA) or vertebrobasilar artery. We experienced unique AVMs arising in the midline Galenic region, receiving blood supply from the ICA/vertebral artery systems and the external carotid artery system. We retrospectively reviewed data on eight patients who had an AVM arising in the Galenic region and were treated in the University of Tokyo Hospital between 1990 and 2019. The median age at diagnosis was 62 years. Three cases (38%) presented with obstructive hydrocephalus due to aqueduct obstruction caused by an engorged vein of Galen. In all cases, feeders from dural arteries were present and the vein of Galen was the primary drainer. All patients underwent stereotactic radiosurgery. Five patients were followed for > two years; nidus obliteration was confirmed in one, and > 75% shrinkage was confirmed in three, while one patient died due to hemorrhage. Altogether, AVMs arising in the Galenic region are rare and exhibit several peculiar characteristics including the presence of dural feeders, an older age at presentation and presentation with obstructive hydrocephalus.