Dural Arteriovenous Fistula (dAVF): Causes, Symptoms and Treatments
Fast facts:
A dural arteriovenous fistula (or dAVF) is a rare abnormal connection between an artery and a vein in the lining of the brain.
Some cases of dAVF go undetected (asymptomatic) until it is found when the patient is being treated for other conditions. For symptomatic patients, the symptoms depend on the location and drainage pattern of the dAVF.
dAVF is treated through a minimally invasive approach called endovascular embolisation, where doctor insert a catheter into an artery in the groin, find the location of the fistula, and close it off.
Image credit: Jonathan A. Borden, M.D., Dural AVF of superior sagittal sinus draining into subarachnoid veins. Type IIIb
What Is Dural Arteriovenous Fistula?
A dural arteriovenous fistula (or dAVF) is a rare vascular condition where there’s an abnormal connection between an artery and a vein in the dura mater. The dura mater is a thick membrane that covers and surrounds the brain and spinal cord.
This anomaly occurs when oxygen-rich blood in the dural artery (which is under high pressure and flow) goes directly into the dural vein (which handles low-pressure oxygen-depleted blood returning to the heart). This congests the brain’s venous system and impedes normal brain circulation. It can result in rupture, which then leads to brain haemorrhage and other issues within the nervous system.
The dAVF tends to occur later in life and in response to other disorders, surgery or injury. It is not genetic.
Low magnification micrograph of an arteriovenous malformation in the brain.
Image credit: Nephron, CC BY-SA 3.0, via Wikimedia Commons
Symptoms of Dural Arteriovenous Fistula
Some cases of dAVF go undetected (asymptomatic). In fact, 1 of 4 cases are incidentally found; meaning this it is found when the patient is being treated for other conditions.
For symptomatic patients, the neurological symptoms depend on the location and drainage pattern of the dAVF. Patients commonly complain of bruit or pulsatile tinnitus.
Bruit is a condition described as a whooshing sound, caused by unusual blood flow, that is always in rhythm with the heartbeat
Pulsatile tinnitus is described as ringing in the ears
They may also experience vision problems, which include:
Visual deterioration
Eye bulge
Swelling in the eye lining
Eye-related palsies
Cavernous sinus syndrome
Some patients may also experience headaches, seizures, or if they rupture, strokes.
Call 000 immediately if you or someone you are with is experiencing seizure or symptoms indicating brain haemorrhage:
Sudden, severe headache
Nausea and/or vomiting
Weakness or numbness on one side of the body
Difficulties in speaking or understanding speech
Loss of vision or double vision
Balance difficulties
What Causes Dural Arteriovenous Fistula?
It’s still unclear exactly why dural arteriovenous fistulas form. However, some doctors think it can be a result of significant head trauma in the past, consequences of brain surgery, or a blood clot in a venous sinus.
Anyone may develop a dAVF, but we find that most patients are usually women in their fifties (or older).
How to Diagnose Dural Arteriovenous Fistula
If you’re experiencing symptoms of dAVF, your GP may recommend some diagnostic tests to be carried out. This includes a CT scan, CT angiogram, MRI, or a standard angiogram.
A CT head scan will let us know if there is a fluid buildup due to cortical vein blood pressure or actual bleeding. An MRI will tell us what the dAVF looks like and its impact, as well as the location of micro-haemorrhages in the brain’s venous system, if there are any. An angiogram shows how many fistulae exist, the blood vessels’ structure, and where they’re located and decide if treatment is necessary.
How to Treat Dural Arteriovenous Fistula
We carefully assess each patient to determine the best approach to treatment.
The most common one is endovascular embolisation, a minimally invasive approach to treating dAVF. In this procedure, we insert a catheter into an artery in your groin and work our way up to the location of the fistula.
The goal is to normalise the blood flow; to do that, we close off the fistula using a metal coil, a balloon, or a medical-grade glue. There are cases where placing a stent is necessary.
The procedure takes 1 to 2 hours to complete, and the recovery period is usually 24–48 hours. This is performed while you are under general anaesthesia, so an overnight stay in the hospital is required.
dAVF vs AVM
If dAVFs are found in the lining of the brain (dura mater) or spinal cord, AVMs, on the other hand, are found within the tissue of the brain or spinal cord. You can read all about arteriovenous malformations (AVMs) here.
DISCLAIMER: The information provided is designed to support, not replace, the relationship that exists between a patient or site visitor and their existing healthcare professionals.
Verified by: Dr Stephen Winters
Dr Hugh Stephen Winters is a neurologist with four years of exhaustive training in interventional neuroradiology, which includes a year of Clinical and Procedural Fellowship in Interventional Neuroradiology at the Erlanger Medical Center in Tennessee.