Progressive AVM Thrombosis after Onyx Embolization with Angiographic Cure.

Intracranial arteriovenous malformations (AVMs) have a cumulative risk of hemorrhage and refractory seizures. Pre-surgical Onyx embolization of cerebral AVMs improves clinical outcome. A 45-year-old man with a history of seizures was diagnosed with a Spetzler-Martin grade 4 AVM in the right occipital lobe. As per initial assessment, three to four sessions were required for adequate devascularization of the AVM before offering either surgery or gamma knife treatment. We achieved 10% and 70% devascularization in the first and second stage Onyx18 embolization respectively. Subsequent bilateral internal carotid, external carotid, vertebral and right posterior cerebral artery superselective angiography performed six weeks after the second stage of embolization demonstrated unexpected complete angiographic cure of the AVM.