[The dural arteriovenous fistula - an unimposing morphological correlate with imposing consequences]

Dural arteriovenous fistulas (DAVFs) are abnormal arteriovenous shunts located within the dura mater representing approximately 10 - 15 % of all arteriovenous shunts in the central nervous system. The aetiology of spontaneous DAVFs remains to be elucidated. The symptoms associated with DAVFs can be highly variable and dependent upon the direction of the blood flow, the amount of arteriovenous shunting and the specific location of the fistula. Considering the diversity of clinical presentation in the setting of unremarkable imaging results, diagnosing a DAVF can be difficult. To avoid permanent neurological deficits due to DAVFs, it is important to consider the possibility of a DAVF whenever one encounters unclear neurological symptoms and to initiate appropriate diagnostic procedures including intraarterial DSA and MRI/MRA. The current DAVF classification accounts for the disparity of clinical symptoms, therapeutic/interventional implications as well as vital complications depending on each particular fistula subtype. While type I DAVFs drain anterogradely into a cerebral sinus and mainly cause functional deficits, the risk for severe intracerebral bleeding increases when DAVFs drain retrogradely (type II), or into cortical (types III and IV), perimedullar or radiculo-medullar veins (type V), respectively. In particular in the case of type IIb to V DAVFs, the appropriate treatment option is a complete fistula occlusion by transvenous embolization, transarterial glue or particulate embolization or surgery. In the following we systematically explain the differential anatomy underlying DAVFs and discuss possible symptoms and necessary diagnostic and therapeutic means. In that, we are seeking to increase attention for this rare, but clinically relevant neurological disease.