Dural Arteriovenous Fistula (DAVF)

What is a dural arteriovenous fistula (DAVF)?

DAVFs are vascular lesions in which dural arteries connect directly to veins or dural venous sinuses, without the normal intervening capillary bed. This creates a high-pressure “shunt” that can redirect flow into venous pathways not designed to tolerate arterial pressures.

Depending on where the blood drains—into a venous sinus only, or into cortical veins—a DAVF may behave as a relatively benign lesion, or it may carry a substantial risk of intracranial hemorrhage and permanent neurological deficit.

What causes it and how is it classified?

DAVFs may be:

• Acquired: after trauma, prior surgery, dural sinus thrombosis, inflammation, or hormonal states (e.g., pregnancy)
• Congenital: present from birth but may become symptomatic later in life

Common anatomic locations include:

• Tentorial region, often supplied by the middle meningeal artery
• Anterior cranial fossa (ethmoidal DAVF)
• Cavernous sinus region—often presenting with ocular symptoms
• Posterior cranial fossa

Is it dangerous? What do Cognard/Borden types mean?

Not all DAVFs carry the same risk. The single most important determinant is the venous drainage pattern.

• Lower-risk DAVFs (Cognard I, Borden I): drainage is limited to a dural venous sinus, without reflux into cortical veins. These lesions often cause pulsatile tinnitus and are less likely to hemorrhage.
• Higher-risk DAVFs (Cognard IIb, IIa+b, III, IV, V / Borden II–III): there is retrograde drainage into cortical or spinal venous pathways (venous reflux), associated with a meaningful risk of hemorrhage or progressive neurological injury.

What symptoms can a DAVF cause?

Symptoms depend on lesion location and venous drainage:

• Pulsatile tinnitus, often unilateral
• Headache or a sense of intracranial pressure
• Visual changes, diplopia, or proptosis (prominent eye)
• Cranial neuropathies (facial weakness, eye-movement palsies, etc.)
• Seizures or focal neurological deficits
• Sudden hemorrhage (intracerebral or subarachnoid)
• More rarely, myelopathy (Type V with spinal venous drainage)

Some DAVFs are found incidentally on imaging. In those cases, the decision to treat is driven primarily by the angiographic risk profile, not by symptoms alone.

Which tests are needed for diagnosis?

Diagnosis is established using a combination of:

• Non-contrast CT: to evaluate hemorrhage or edema
• CT angiography (CTA): may show dilated veins and abnormal flow patterns
• MRI/MRA: can demonstrate enlarged surface vessels, venous congestion, and related parenchymal changes
• Digital subtraction angiography (DSA): the gold standard—defines, in real time, arterial feeders, shunt architecture, and precise venous drainage.

When is observation reasonable and when is treatment required?

For low-risk DAVFs (no cortical venous reflux; typically Cognard I):

• Close observation with interval imaging and/or angiographic surveillance may be appropriate
• Treatment may still be recommended if symptoms (e.g., severe pulsatile tinnitus) are significantly affecting quality of life

For high-risk DAVFs (Cognard IIb, IIa+b, III, IV, or Type V):

• Active treatment is generally recommended because of the elevated risk of hemorrhage, progressive neurological deficit, or myelopathy
• The goal is definitive disconnection/obliteration of the pathological shunt

How is endovascular therapy performed (TAE / TVE)?

Endovascular treatment is performed through a catheter introduced via the groin or wrist, under sedation or general anesthesia depending on the complexity of the case.

Transarterial Embolization (TAE)

• A microcatheter is navigated into the arterial feeder supplying the fistula
• Liquid embolic agents (e.g., NBCA “glue”, Onyx) are delivered to seal the shunt
• Often ideal for smaller DAVFs and lesions without a durable venous sinus drainage compartment

Transvenous Embolization (TVE)

• The catheter is advanced through the venous system into the pathological venous sinus or draining vein
• Coils and/or liquid embolics are used to occlude the abnormal segment
• Often preferred for larger or more complex DAVFs involving a portion of a venous sinus

In many cases, combined arterial and venous approaches are used to achieve the safest and most complete cure.

When is surgery needed and what is the role of radiosurgery?

Microsurgical treatment may be recommended when:

• Endovascular access is not feasible or cannot reliably achieve complete cure
• The DAVF is in a location where targeted surgical disconnection can be performed safely
• There is associated mass effect or compressive pathology requiring decompression

Surgery most commonly involves precise interruption of the pathological draining vein or isolation of the affected sinus segment.

Stereotactic radiosurgery (SRS) may be used:

• When both endovascular and open surgical options carry unacceptable risk
• For residual or recurrent DAVFs following other therapies

Because its effect is delayed (months to years), SRS is typically not first-line for very high-risk lesions—unless no safer alternative exists.

What are the risks, cure rates, and likelihood of recurrence?

Endovascular therapy:

• Modern series report high angiographic cure rates, particularly with contemporary liquid embolics (e.g., Onyx) in appropriate lesions
• Low-risk DAVFs may close completely in a single session
• Potential complications include ischemic or hemorrhagic stroke, vessel perforation, and unintended embolic material migration

Surgery:

• When the target anatomy is clearly defined, definitive cure rates are very high
• Risks include bleeding, infection, and location-dependent neurological injury

Recurrence can occur, particularly after partial treatment or in more complex angioarchitecture. For this reason, structured angiographic follow-up is essential after therapy.

How do we decide what is right for you?

Treatment strategy is individualized based on:

• DAVF type (Cognard/Borden) and presence of cortical venous reflux
• Anatomic location (e.g., cavernous sinus, transverse–sigmoid sinus, anterior cranial fossa)
• Age, comorbidities, and overall clinical status
• Presentation (tinnitus vs hemorrhage vs focal deficit)
• Technical feasibility of TAE/TVE, microsurgery, SRS, or a combined approach

At Neuroknife, decisions are guided by multidisciplinary case review (neurosurgery, interventional neuroradiology, radiation oncology, anesthesiology) and a detailed discussion with you in clear, patient-centered language.

How does it affect daily life and what follow-up is needed after treatment?

After endovascular therapy or surgery:

• Hospitalization is typically brief (often 1–3 days for endovascular therapy; longer if craniotomy is required)
• Temporary restriction of strenuous exercise and heavy physical work
• Avoidance of anticoagulants/antiplatelet agents unless clearly indicated (individualized decision-making)

For higher-risk lesions, scheduled DSA or CTA/MRA follow-up is performed to confirm complete occlusion and to exclude recurrence.