Dural arteriovenous fistulas (d-AVFs) are malformations caused by abnormal connections between your artery and vein in the dura, an outer covering of the spinal cord or brain. These malformations usually appear later in life and are not seen to have a genetic tendency.
While there are many causes for these d-AVFs, blockage or narrowing of the brain’s venous sinuses is among the commonest causes.
Symptoms of Dural Arteriovenous Fistulas
Some patients with dural AVFs may not have any symptoms. But when present, they can be classified as benign or aggressive symptoms.
These symptoms can be due to hemorrhage/bleeding in the brain or non-hemorrhaging neurological deficits (NHND). Hemorrhagic symptoms include a sudden headache of varying intensity depending on the size and location of the bleeding.
On the other hand, symptoms of NHND develop gradually and cause symptoms based on its location. Some common symptoms include speech or language difficulty, seizures, dementia, face pain, pricking sensations, coordination problems, and apathy. Pressure symptoms can also be present such as nausea, vomiting, and headache.
Common symptoms include pulsatile tinnitus, a bruit behind the ear, and vision problems such as eye bulge, visual deterioration, and swelling in the eye lining.
Symptoms that indicate a medical emergency
If you have any of the mentioned symptoms, seek immediate medical care:
- A sudden severe headache
- Paralysis of one side of the body
- Difficulty in speaking
- Double vision
- Loss of vision
- Loss of balance
If you have symptoms of dural AVF, your doctor may ask for magnetic resonance imaging (MRI) and non-contrast head computerized tomography (CT).
- MRI/CT: It can help determine the secondary changes in the brain due to d-AVF. However, it is difficult to see the dural AVF on MRI or CT. Enlarged blood vessels at specific sites can raise a suspicion of this condition.
DSA (Digital Subtraction Angiography / Catheter-based cerebral angiography):
This is the gold standard test to diagnose this condition. It not only can diagnose this but can also helps in making treatment plan and assessing the benign Vs. aggressive nature of this condition.
After the initial CT/MRI scan, your doctor may advise this angiography that will help to define:
- Blood vessel structure of the fistula
- Location and number of fistulae
- Anatomy of blood vessels
- The extent of blockage or narrowing in the dural sinus
- If the affected veins are dilated and their extent
- Endovascular embolization: this is the mainstay in d-AVF treatment. It is a minimally invasive procedure involving the insertion of a flexible, thin tube (catheter) through a cut in the groin to deliver obstructive materials like glue into the AVF and close the abnormal connection. This form of therapy is highly evolved and carries a low risk of complications.
- Stereotactic radiosurgery: It uses a highly concentrated radiation beam that focuses on the site of AVM. The radiation beam damages the blood vessels and forms scar tissue, stopping the blood flow into the AVF. It is not a typical surgery as the procedure is cut-free.
- Surgical removal: It is an ideal option if the fistula is very small and is at a location that is easily accessible surgically. Resection is usually done when the AVF can be removed with little risk of seizures or bleeding.