A dural arteriovenous fistula (dAVF) is an abnormal direct connection, or shunt, between an artery and vein located in the covering of the brain or spinal cord (called the dura mater). Dural AV fistulae represent only 10-15% of all AVMs, which are rare lesions. They may be congenital or may result from trauma or natural formation of new blood vessels in cases in which a major draining vein (or sinus) in the brain is blocked or clotted.
Typical symptoms include headaches, ringing in the ears that beats with the heartbeat (called ‘pulsatile tinnitus’), and visual changes. Cerebral angiography is the gold standard test for evaluating a dural AVF. A dural AVF is classified by how the artery drains into one or more veins. If there is high pressure in the fistula, flow in the vein may backup, and become dangerous, as such high-pressure could result in bleeding. It is recommended that a dural AVF be treated if it is causing refractory or intolerable symptoms, if it results in a neurologic deficit, or if it has bled or is at significant risk of bleeding.
Most dural AV fistulae are treated endovascularly by injecting glue-like substances (a process called ‘embolization’) through a small tube, or microcatheter, that is guided into the vessel from an artery puncture site (typically in the groin). In rare cases, if treatment cannot be achieved with endovascular methods alone, open surgery may be required. There are some dural AV fistulae that may be treated successfully with radiosurgery as well.
Justin F. Fraser, MD