External carotid artery embolization of dural arteriovenous malformations involving the cavernous sinus. Outcome and role of venous thrombosis.

Nine patients with dural arteriovenous malformations (AVMs) in the region of the cavernous sinus were treated by means of external carotid artery (ECA) embolization using polyvinyl alcohol. All AVMs received vascular supply from both the ECA and the internal carotid artery. Seven cases were clinically cured after embolization, while 2 cases with cortical venous drainage and high flow through the shunt were not completely cured. Venous thrombosis was observed in 5 cases before and in 9 after embolization. In 6 cases the drainage pattern changed owing to venous thrombosis. Complete thrombosis of the cavernous sinus was found on a follow-up angiography in 2 cases. Formation of venous thrombosis and occlusion of feeding arteries are crucial factors for success of ECA embolization. Dural AVMs with cortical venous drainage and high flow cannot be relieved by ECA embolization alone owing to difficulty in obtaining thrombosis of the veins.