Endovascular Management of Intracranial Dural Arteriovenous Fistulas: Transarterial Approach

An anatomical-angiographic classification for carotid-cavernous sinus fistulas is introduced and a series of 14 patients with spontaneous carotid-cavernous sinus fistulas is reviewed to illustrate the usefulness of such a classification for patient evaluation and treatment. Fistulas are divided into four types: Type A are direct high-flow shunts between the internal carotid artery and the cavernous sinus; Type B are dural shunts between meningeal branches of the internal carotid artery and the cavernous sinus; Type C are dural shunts between meningeal branches of the external carotid artery and the cavernous sinus; and Type D are dural shunts between meningeal branches of both the internal and external carotid arteries and the cavernous sinus. The anatomy, clinical manifestations, angiographic evaluation, indications for therapy, and therapeutic options for spontaneous carotid-cavernous sinus fistulas are discussed.

To review the symptoms and progression of dural arteriovenous fistulas (AVFs) and correlate the findings with various angiographic patterns. Patterns of venous drainage allowed classification of dural AVFs into five types: type I, located in the main sinus, with antegrade flow; type II, in the main sinus, with reflux into the sinus (IIa), cortical veins (IIb), or both (IIa + b); type III, with direct cortical venous drainage without venous ectasia; type IV, with direct cortical venous drainage with venous ectasia; and type V, with spinal venous drainage. Type I dural AVFs had a benign course. In type II, reflux into the sinus induced intracranial hypertension in 20% of cases, and reflux into cortical veins induced hemorrhage in 10%. Hemorrhage was present in 40% of cases of type III dural AVFs and 65% of type IV. Type V produced progressive myelopathy in 50% of cases. This classification provides useful data for determination of the risk with each dural AVF and enables decision-making about the appropriate therapy.

A classification is proposed that unifies and organizes spinal and cranial dural arteriovenous fistulous malformations (AVFMs) into three types based upon their anatomical similarities. Type I dural AVFMs drain directly into dural venous sinuses or meningeal veins. Type II malformations drain into dural sinuses or meningeal veins but also have retrograde drainage into subarachnoid veins. Type III malformations drain into subarachnoid veins and do not have dural sinus or meningeal venous drainage. The arterial supply in each of these three types is derived from meningeal arteries. The anatomical basis of the proposed classification is presented with several cases that illustrate the three types of dural AVFMs. A rationale for the treatment of spinal and cranial dural AVFMs according to their anatomical characteristics is discussed.