Dural arteriovenous fistulas
Dural arteriovenous fistulas (dAVFs) are irregular connections between arteries and veins that occur in the dura mater, the tough covering over the brain or spinal cord. These abnormal passageways, known as arteriovenous fistulas, can lead to significant health issues, including bleeding in the brain or other serious symptoms.
Epidemiology
Dural AVFs are rare conditions, most commonly occurring between the ages of 50 and 60. They are not typically hereditary, meaning children are not at increased risk if a parent has a dAVF.
Etiology
While the exact cause of most dAVFs remains unknown, it is believed that those involving large brain veins may form when one of the brain's venous sinuses narrows or becomes blocked. Venous sinuses are channels that help return circulated blood from the brain back to the heart. Known causes can include traumatic head injuries, infections, previous brain surgeries, blood clots in deep veins, or tumors.
Symptoms
Symptoms of dAVFs can vary widely and may be benign or aggressive:
Aggressive Symptoms
Aggressive dAVF symptoms can result from intracerebral hemorrhage (bleeding in the brain), which often causes a sudden headache and other symptoms depending on the hemorrhage's location and size. Nonhemorrhagic neurological deficits (NHNDs) may also occur, including seizures or changes in mental abilities, which develop gradually over days to weeks.
Aggressive symptoms can include:
- Sudden headache
- Trouble walking and falls
- Seizures
- Speech or language issues
- Facial pain
- Dementia
- Parkinsonism (slowed movement, stiffness, and tremor)
- Trouble with coordination
- Burning or prickling sensations
- Weakness
- Apathy
- Failure to thrive
- Symptoms related to increased pressure, such as headaches, nausea, and vomiting
Other Symptoms
Other dAVF symptoms can affect hearing, such as pulsatile tinnitus (a rhythmic sound in the ear that occurs with the heartbeat). Visual disturbances may also occur, including:
- Vision changes
- Eye bulge
- Swelling in the eye lining
- Paralysis of a muscle in or around the eye
- Rarely, dementia due to increased pressure in the brain's blood vessels
When to Seek Medical Attention
Immediate medical attention is required if you experience a seizure or symptoms suggesting brain hemorrhage, including:
- Sudden, severe headache
- Nausea and vomiting
- Weakness or numbness on one side of the body
- Trouble speaking or understanding speech
- Loss of vision or double vision
- Trouble with balance
Risk Factors
Risk factors for dAVFs include conditions that predispose individuals to venous thrombosis (blood clots in the veins). Changes in blood clotting can increase the risk of narrowing or blocking the venous sinuses. dAVFs are most common in individuals aged 50 to 60, but they can also occur in younger people and children. Additionally, noncancerous tumors in the membranes surrounding the brain and spinal cord may be associated with dAVFs.
Diagnosis
The diagnosis of dAVFs typically involves imaging studies such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), computed tomography (CT) scans, or digital subtraction angiography (DSA). These tests help visualize the abnormal connections between arteries and veins.
Treatment
Treatment for dAVFs usually involves an endovascular procedure or stereotactic radiosurgery to block blood flow to the dAVF. In some cases, surgical intervention may be necessary to disconnect or remove the dAVF.
Endovascular Treatment
This minimally invasive procedure involves inserting a catheter through the blood vessels to the site of the fistula, where materials such as coils, glue, or other agents are used to block the abnormal connections.
Stereotactic Radiosurgery
This non-invasive technique uses focused radiation to target and close the abnormal blood vessels.
Surgery
In some cases, traditional surgical methods may be required to directly access and remove or disconnect the dAVF.
Conclusion
Dural arteriovenous fistulas are rare but potentially serious conditions that require prompt diagnosis and treatment to prevent severe complications. Understanding the symptoms, risk factors, and available treatments can help manage and mitigate the risks associated with dAVFs.
Sources
- Mayo Clinic. (n.d.). Dural arteriovenous fistula (dAVF). Retrieved from Mayo Clinic
- American Association of Neurological Surgeons (AANS). (n.d.). Arteriovenous fistulas. Retrieved from AANS
- National Organization for Rare Disorders (NORD). (n.d.). Dural arteriovenous fistula. Retrieved from NORD
