Dural arteriovenous fistula (DAVF)

Dural arteriovenous fistulas (DAVF) are malformed connections between arteries and veins in the covering of the brain and spinal cord (dura mater).

Dural AV fistulas are a type of arteriovenous malformation (AVM). An arteriovenous malformation, or fistula, is direct connection between an artery and a vein.

Usually, a bed of capillaries separates arteries and veins. Capillaries are tiny blood vessels that deliver oxygen and nutrients to tissues and carry away waste products. A DAVF bypasses the capillaries, which can lead to high pressure in the receiving veins.

The term dural refers to the location of the arteriovenous fistula. The dura mater, or dura, is a thick layer of tissue that surrounds and protects your brain and spinal cord. Spinal dural AV fistulas usually occur in the middle to lower region of the spine and are five times more common in men than women.

Is DAVF life-threatening?

The most serious complication of DAVF is bleeding in the brain, known as a hemorrhage or hemorrhagic stroke. The bleeding can damage brain tissue and lead to death.

A stroke is a medical emergency. Call 911 if you experience:

• Confusion and difficulty speaking
• Drooping on one side of the face
• Sudden and severe headache
• Weakness in one arm or leg

This rare cerebrovascular condition occurs in fewer than one in 100,000 people each year. DAVF is most common in people between the ages of 40 and 60. Due to the risk of brain bleeding that can occur with a DAVF, this condition requires immediate evaluation and care by an experienced team.

Penn Medicine's cerebrovascular specialists offer leading-edge treatments for dural arteriovenous fistulas to close these artery-vein connections and safeguard your health.

Most of the time, doctors are not sure what causes DAVFs. Some possible causes include:

• Infection
• Narrowing or blockage in the venous network of the brain
• Past head trauma
• Previous brain surgery

The main tests doctors use to identify DAVFs are magnetic resonance angiography (MRA) and CT angiography (CTA). These are specialized MRI and CT scans that show:

• Abnormal connections
• Areas of enlargement
• Blockages
• Bleeding in your brain

If CTA or MRA shows a DAVF, your doctor will likely order cerebral angiography to confirm the diagnosis and plan treatment. This is a minimally invasive test in which your doctor inserts a catheter (thin tube) into a blood vessel in your groin or arm. Your doctor threads the catheter to the affected area and releases a contrast dye. Imaging tests capture the dye moving through your blood vessels and highlight the details of the fistula.

Your doctor will assess the severity of the DAVF to determine the appropriate treatment. Several classification systems are available, including the Borden and Cognard methods. Both systems grade the DAVF on the basis of the blood flow pattern in and around the fistula. DAVF classification ranges from relatively harmless (benign) to likely to hemorrhage (aggressive).

Treatment often cures a DAVF and may resolve symptoms or prevent new symptoms. But if damage to the brain or spinal cord occurred before treatment, you may have permanent losses in function.

Your treatment will depend on your symptoms, overall health and risk of hemorrhage. If you have a low grade, benign DAVF, your doctor may opt to observe you over time. You may never need treatment.

Higher-risk DAVFs usually require surgical treatment to disconnect the arteriovenous connection. Our cerebral disease specialists offer the most advanced treatments available today, including:

• Endovascular embolization: This is a minimally invasive procedure. Your doctor inserts a catheter into a blood vessel and guides it to the DAVF. Your doctor may inject different types of materials, such as metal coils or glue, to block the fistula.
• Microsurgery: This is usually an option if endovascular treatments are not possible or have failed. The surgeon removes a section of the skull and uses a surgical microscope and specialized tools to disconnect the DAVF. We use imaging during surgery to make sure we completely disconnect the fistula. This helps prevent the need for additional operations.
• Radiosurgery: Doctors use this technique for less severe DAVFs. It is also an option for people who cannot undergo surgery or if endovascular or microsurgical procedures were not effective. Radiosurgery aims precise beams of radiation at the DAVF. The radiation damages the blood vessels which deteriorate and close over time.