The dural arterio-venous fistula (dAVF) is a vascular malformation constituted by an anomalous communication between an artery and a vein. The passage between them is direct, without the interposition of a capillary bed, located in the territory of the dura mater (one of the three layers that make up the meninges).
The afferent artery is generally a meningeal artery that flows into an arterial reticulum (nidus) located within the thickness of the dura mater. From here, some discharge veins depart (arterialised veins because they transport blood with arterial pressure), which often converge into a dural venous sinus. The direct arterio-venous communication determines a pressure overload in the venous structures composing the fistula. In the event that it involves other cerebral veins, this overload may cause brain hemorrhage.
The pathogenic mechanism is unknown, but a correlation between cardiovascular diseases, previous craniotomies, thrombosis of the dural venous sinuses and the development of dAVF has been observed.
The hypothesis of a possible infectious origin is also particularly accredited.
Dural arterio-venous fistulas can be both cerebral and spinal, i.e. located in a territory of the dura mater that surrounds the spinal cord.