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). 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, 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 identifiable causes, it's thought that dAVFs involving large brain veins usually develop 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.
Some people with a dAVF may not have any symptoms. However, apparent 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 non-hemorrhaging neurological deficits (NHNDs).
Bleeding in the brain often causes sudden onset of a 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 a set of symptoms related to its location. These aggressive symptoms can include seizures, speech or language issues, face pain, dementia, Parkinsonism, coordination issues, burning or prickling sensations, weakness, apathy, failure to thrive, and symptoms related to increased pressure such as headaches, nausea and vomiting.
More benign dAVF symptoms can include both hearing issues (often a bruit behind the ear, also known as pulsatile tinnitus) and vision problems including visual deterioration, eye bulge, swelling in the eye lining, eye-related palsies and 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, infection, previous brain surgery 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 predisposing to vein thrombosis, such as coagulation abnormalities that increase the risk for 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.