Cranial Dural Arteriovenous Fistulas: Clinical Findings and Radiologic Diagnostics

Abstract

Cranial dural arteriovenous fistulas (DAVFs) are a unique acquired neurovascular entity, which may develop in the dura mater and adjacent pial veins. These arteriovenous shunting lesions of the dura are quite distinct from archetypal cerebral arteriovenous malformations because of pathologic, pathogenetic, and clinicobiological criteria. There remains some confusion and debate regarding proper nomenclature, pathophysiology, and pathoetiologic mechanisms. Clinical symptoms are highly variable and depend on the specific location of the lesion, the extent of arterial supply, and especially on the specific pattern of venous drainage. The Department of Neuroradiology, Kantonsspital Aarau, Switzerland, has consecutively assessed 185 patients with cranial DAVFs in the last 17 years. Treatment consisted of observational management, surgical resection, transarterial or transvenous embolization, or a combination of these therapies. A group of 95 aggressive cranial DAVFs (Borden grade 2 or 3) was analyzed. In regard to venous pattern of their venous drainage the DAVFs were classified in five groups considering both the location and the possible pathogenesis. The patients with aggressive cranial DAVFs presented with hemorrhage, neurologic deficit, seizure, and dementia. The morphological development of DAVFs seems to depend on the flow volume of the venous recipient. A pronounced generation of pathologic AV shunts usually takes place at the level of large dural sinuses. By contrast, a delayed development of AV shunts with a low shunt volume occurs in a venous recipient with low AV pressure gradients. Transarterial treatment of DAVFs is chosen to improve symptoms and/or to prevent catastrophic consequences of the natural history of this disease. Once the venous side has been occluded, all arterial input (i. e., venous arterialization) will permanently cease. An anatomic cure can be achieved by obliteration of the venous recipient in three fashions: transvenous occlusion of sinus, transvenous occlusion of venous pouch outside the sinus lumen, or transarterial occlusion of venous channel.