Dural arteriovenous fistulas (dAVFs) are abnormal connections between an artery and a vein in the tough covering over the brain or spinal cord (dura mater). In this rare condition, abnormal passageways between arteries and veins (arteriovenous fistulas) may occur in the brain, spinal cord or other areas of your body.
Dural AVFs tend to occur later in life (50 to 60 years of age), and they're not typically passed on genetically — children aren't more likely to develop a dAVF simply because their parent has.
Although some dAVFs stem from known causes, it's thought that dAVFs involving large brain veins usually form due to narrowing or blockage of one of the brain's venous sinuses, which normally route circulated blood from the brain back to the heart.
Treatment for dAVF usually involves an endovascular procedure or stereotactic radiosurgery to block the blood flow to the dAVF. Or, you may need surgery to disconnect or remove the dAVF.
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Some people with a dAVF may not have any symptoms. However, noticeable symptoms can be characterized either as aggressive or benign.
Aggressive dAVF symptoms can result either from bleeding in the brain (intracerebral hemorrhage) or from neurological effects of nonhemorrhaging neurological deficits (NHNDs).
Bleeding in the brain often causes a sudden headache with varying degrees of neurological disability related to the location and size of the hemorrhage.
By contrast, an NHND usually develops more gradually, over days to weeks, and typically produces symptoms related to its location.
These aggressive symptoms can include:
- Difficulty walking, falls
- Speech or language issues
- Facial pain
- Coordination issues
- Burning or prickling sensations
- Failure to thrive
- Symptoms related to increased pressure such as headaches, nausea and vomiting.
Other dAVF symptoms can include hearing issues, such as a bruit behind the ear, also known as pulsatile tinnitus. Other symptoms include vision problems such as:
- Visual deterioration
- Eye bulge
- Swelling in the eye lining
- Eye-related palsies
- Cavernous sinus syndrome.
In rare cases, progressive dementia may occur due to venous hypertension.
When to see a doctor
Make an appointment with a doctor if you develop any signs or symptoms that seem unusual or that worry you.
Seek medical help immediately if you experience any symptoms of seizure, or symptoms that suggest brain hemorrhage, such as:
- Sudden, severe headache
- Weakness or numbness on one side of the body
- Difficulties in speaking or understanding speech
- Loss of vision
- Double vision
- Balance difficulties
Most dural arteriovenous fistulas have no clear origin, although some result from identifiable causes such as traumatic head injury (or traumatic AV fistula), infection, previous brain surgery, venous thrombosis or tumors. Most authorities think that dAVFs involving the larger brain veins usually arise from progressive narrowing or blockage of one of the brain's venous sinuses, which route circulated blood from the brain back to the heart.
Genetic risk factors for dAVFs include those predisposed to blood clots in the vein (vein thrombosis). This may include abnormalities in the way the blood clots, which may increase the risk for a blockage or narrowing (occlusion) of the vein sinuses.
Most frequently, dAVFs affect people in their late-middle years (roughly from 50 to 60 years old). However, dAVFs can occur in younger age groups as well, including in children.
Recent evidence does suggest that benign meningeal tumors may also be associated with the development of dAVFs.