What is a Dural AV Fistula?

A dural AV fistula, also called a dural arteriovenous fistula or dAVF, is an abnormal connection between arteries and veins in the dura mater, the tough protective covering around the brain and spinal cord. Instead of blood flowing through normal small vessels, blood passes directly from an artery into a vein or venous sinus.

Some dural AV fistulas are low-risk and may cause mild or no symptoms. Others can create abnormal pressure in the veins around the brain. A dAVF with cortical venous reflux, meaning blood drains backward into veins on the brain surface, may carry a higher risk of brain hemorrhage, stroke-like symptoms, seizures, or neurological decline.

De Novo Brain & Spine evaluates adult patients with suspected or confirmed dural AV fistula to help determine the appropriate next step. Evaluation may include neurological examination, MRI, MRA, CT angiography, catheter angiography, review of venous drainage patterns, monitoring, or coordination with cerebrovascular and neurointerventional specialists when appropriate.

Common Signs and Symptoms

Dural AV fistula symptoms depend on the fistula’s location, blood flow pattern, venous drainage, and whether there is bleeding or pressure on nearby brain, eye, ear, or spinal cord structures. Some dural AV fistulas are found incidentally during imaging for another reason.

Common signs and symptoms may include:

• Pulsatile tinnitus, often described as a whooshing sound that follows the heartbeat
• Headaches
• Dizziness or balance problems
• Vision changes, including blurred vision or double vision
• Eye redness, eye swelling, bulging eye, or eye movement problems when the fistula involves the cavernous sinus region
• New-onset seizures
• Weakness, numbness, or tingling in the face, arm, or leg
• Trouble speaking, understanding speech, or finding words
• Memory problems, confusion, or difficulty concentrating
• Stroke-like symptoms
• Symptoms of brain hemorrhage, such as sudden severe headache, vomiting, confusion, seizure, or sudden neurological changes
• Progressive walking difficulty, leg weakness, numbness, or bladder changes in selected spinal dural AV fistulas

Seek emergency medical care or call 911 for sudden severe headache, first-time seizure, sudden weakness, sudden speech difficulty, sudden vision loss, severe confusion, loss of consciousness, repeated vomiting, or rapid neurological decline.

What Causes This Condition?

A dural AV fistula forms when arteries develop an abnormal direct connection to veins or venous sinuses within the dura. The exact cause is not always known.

Possible causes or related factors may include:

• Changes in venous pressure or venous drainage
• Prior dural venous sinus thrombosis, meaning a blood clot in a venous sinus
• Head trauma in selected cases
• Prior surgery or procedures near the involved blood vessels in selected cases
• Infection, inflammation, or other conditions affecting blood vessels in some cases
• Hypercoagulable conditions, meaning conditions that increase the tendency for blood clots, in selected patients
• Spinal vascular changes in some spinal dural AV fistulas

These factors may contribute to some dural AV fistulas, but they are not present in every patient. The clinical risk depends less on the suspected cause and more on the fistula’s location, venous drainage pattern, symptoms, and whether there is cortical venous reflux or hemorrhage.

How It Is Diagnosed?

A dural AV fistula cannot be diagnosed by symptoms alone. Diagnosis usually requires medical history, neurological examination, and vascular imaging.

Common diagnostic steps may include:

• Medical history and neurological examination to evaluate headache, tinnitus, vision, eye movement, strength, sensation, speech, balance, coordination, memory, and alertness
• MRI of the brain or spine to evaluate for abnormal vessels, swelling, bleeding, venous congestion, or related neurological injury
• MR angiography, also called MRA, to evaluate blood vessel patterns
• CT angiography, also called CTA, to assess arteries, veins, venous sinuses, and possible bleeding
• CT scan of the head in urgent situations when hemorrhage or acute neurological symptoms are suspected
• Digital subtraction angiography, also called catheter angiography or cerebral angiography, to define the fistula’s arterial supply, venous drainage, and risk features
• Spinal MRI or spinal angiography when symptoms suggest a spinal dural AV fistula
• Comparison with prior imaging when available to determine whether findings are new, stable, or changing

Catheter angiography is often the most detailed test for confirming a dural AV fistula and planning treatment. The goal of diagnosis is to identify the fistula, understand its drainage pattern, determine whether higher-risk features are present, and decide whether observation or treatment should be considered.

Treatment Options

Dural AV fistula treatment depends on the fistula’s location, symptoms, venous drainage pattern, presence of cortical venous reflux, hemorrhage history, imaging findings, neurological examination, treatment risk, and the patient’s overall health. Not every dural AV fistula requires the same treatment.

Treatment options may include:

• Observation with repeat imaging for selected low-risk dural AV fistulas that are not causing dangerous venous drainage or significant symptoms
• Medication for symptom control in selected cases, although medication does not close the fistula
• Emergency care when a dural AV fistula causes brain hemorrhage, seizure, stroke-like symptoms, or rapid neurological decline
• Endovascular embolization, a catheter-based treatment that uses liquid embolic material, coils, or other agents to close or reduce abnormal blood flow through the fistula
• Microsurgical disconnection when surgery is appropriate to interrupt the abnormal venous drainage or close the fistula
• Stereotactic radiosurgery in selected cases when other approaches are not ideal, although the effect may take time and is not appropriate for every dAVF
• Treatment for brain hemorrhage, hydrocephalus, or increased pressure when bleeding or fluid blockage occurs
• Rehabilitation and supportive care when weakness, speech difficulty, balance problems, vision issues, or cognitive changes are present after bleeding or neurological injury

Treatment may be recommended when a dural AV fistula has higher-risk venous drainage, causes symptoms, has bled, or creates risk for neurological injury. The safest plan depends on detailed vascular imaging and careful review by specialists experienced in cerebrovascular disease.