Overview
Dural arteriovenous fistulas (dAVFs) are unusual connections between blood vessels in the brain's outer covering. This covering is called the dura mater. Dural AVFs can lead to bleeding in the brain or other serious symptoms.
Dural AVFs are rare. They tend to occur between ages 50 and 60. They are not typically genetic, so children are not more likely to develop a dAVF if their parent has one.
Although some dAVFs stem from known causes, most often the cause is not known. It's thought that dAVFs involving large brain veins form when one of the brain's venous sinuses narrows or becomes blocked. Venous sinuses are channels that 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 surgery may be needed to disconnect or remove the dAVF.
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Symptoms
Symptoms of dural arteriovenous fistulas (dAVFs) can be different for each person, depending on where the dAVFs are located. Some people with dAVFs may not have symptoms. When symptoms occur, they may be characterized as benign or aggressive. An aggressive dAVF has more serious symptoms.
Aggressive dAVF symptoms can result from bleeding in the brain, known as intracerebral hemorrhage. Bleeding in the brain often causes a sudden headache. It also may cause other symptoms based on the location and size of the hemorrhage.
Aggressive symptoms also may result from nonhemorrhagic neurological deficits (NHNDs), which can include seizures or changes in thinking and memory. These symptoms usually develop more gradually, over days to weeks. Symptoms are typically related to the area of the brain affected.
Aggressive symptoms can include:
- Sudden headache.
- Trouble walking and falls.
- Seizures.
- Speech or language issues.
- Facial pain.
- Dementia.
- Slowed movement, stiffness and tremor, known as parkinsonism.
- Trouble with coordination.
- Burning or prickling sensations.
- Weakness.
- Lack of interest, known as apathy.
- Failure to thrive.
- Symptoms related to increased pressure, such as headaches, nausea and vomiting.
Other dAVF symptoms can include hearing issues. People with hearing symptoms may hear a rhythmic sound in the ear that occurs with the heartbeat, known as pulsatile tinnitus. Symptoms also may include trouble with vision, such as:
- Vision changes.
- Eye bulge.
- Swelling in the eye lining.
- Paralysis of a muscle in or around the eye.
Rarely, dementia may occur due to increased pressure in the blood vessels in the brain.
When to see a doctor
Make an appointment with your healthcare professional if you have any symptoms that are not usual or that worry you.
Seek medical help immediately if you experience a seizure or symptoms that suggest brain hemorrhage, such as:
- Sudden, severe headache.
- Nausea.
- Vomiting.
- Weakness or numbness on one side of the body.
- Trouble speaking or understanding speech.
- Loss of vision.
- Double vision.
- Trouble with balance.
Causes
It's not clear why dural arteriovenous fistulas (dAVFs) happen. But some things that might cause them include:
- Traumatic head injury.
- Infection.
- Previous brain surgery.
- Blood clots in deep veins.
- Tumors.
Most experts think that dAVFs involving larger brain veins occur from the narrowing or blockage of one of the brain's venous sinuses. The venous sinuses are channels in the brain that route circulated blood from the brain back to the heart.
Risk factors
Risk factors of dural arteriovenous fistulas (dAVFs) include being inclined to blood clots in veins, known as vein thrombosis. Changes in the way the blood clots may increase the risk of a blockage or narrowing of the venous sinuses.
Most often, dAVFs affect people between ages 50 and 60. But they can occur in people at younger ages, including in children.
Research has found that noncancerous tumors found in the membranes that surround the brain and spinal cord may be associated with dAVFs.
Prevention
Because the exact cause of dural arteriovenous fistulas (dAVFs) isn't known, there's no one way to prevent them from happening.