Arteriovenous Malformation: Carotid-Cavernous Fistula
Arteriovenous anomalies are broadly divided into arteriovenous malformations and arteriovenous fistulas. Carotid-cavernous sinus fistula (CCF) is an example of the latter, where a pathologic vascular shunt between the carotid arterial system and the cavernous sinus, or rarely, directly to an ophthalmic or orbital vein. The Barrow classification for CCF divides them into direct (type A) or indirect (types B–D). Type A, high-flow fistula, typically occurs in young adults after trauma resulting in direct communication between the internal carotid artery and the cavernous sinus. Types B and C result from shunts between the cavernous sinus and smaller branches of the internal carotid artery or the external carotid artery, respectively. Type D is a combination of fine branches of both the internal and the external carotid artery communicating with the cavernous sinus.