Brain Dural Arteriovenous Fistula

A fistula is an abnormal connection between an artery and a vein, with a dural arteriovenous fistula (AVF) being once that is positioned on the dura (the lining of the brain). This has the effect of putting high pressure arterial blood into the usually slow flowing veins, and can lead to venous congestion of the brain and sometimes bleeding. There is often no definitive reason why a fistula forms, but in many cases it is felt to be a response to some abnormal clotting in a vessel.

Presentation

Dural AVFs can present in several ways.  Sometimes pulsatile tinnitus (the sound of whooshing blood flow heard when the fistula is located near the ear) or headaches leads to a patient having an MRI scan.  It should be noted that most patients with pulsatile tinnitus do not have a dural fistula.

Occasionally patients can present with eye symptoms (bulging and redness of the eye) if the fistula is into the large venous lake at the back of the eye socket.  This type of fistula is called a carotico-cavernous fistula.

Dural AVFs can also present when they have bled, with the bleeding either being into the brain itself or into the space surrounding the brain.

Whilst MRI scans provide a lot of information about the status of the brain, the definitive diagnosis of a dural fistula is made by cerebral angiography.

Treatment

The treatment options are best discussed with the imaging and diagnostic cerebral angiogram, but include:

  • Endovascular embolisation. Passing a fine catheter from the vessels at the top of the leg up to the region of the fistula in the brain.  Fine platinum coils, glue or other embolic agents are used to block up the abnormal connections.
  • Open surgery. Occasionally it may be necessary to operate on some fistulas that are not accessible to endovascular treatment.
  • Conservative management with serial MRI examinations. Some dural fistulas are felt to carry a low risk of bleeding and progression and are therefore just observed.
Brain Dural Arteriovenous Fistula