Dural Arteriovenous Fistula (DAVF)
Dural arteriovenous fistulas (DAVF) are abnormal connections between arteries and veins near the brain. The word "dura" refers to the membrane that covers the brain. These are acquired lesions that occur most commonly without an obvious cause, but can be associated with trauma, surgery, tumors, or previous infections near the area of the lesion. While dural arteriovenous fistulas are lesions outside the brain, they may present with a wide range of neurologic symptoms. The presentation varies from an asymptomatic state, to ringing or humming in the ear (or pulsatile tinnitus) to life-threatening or fatal bleeding in the brain.
Much of the presentation depends on the venous drainage pattern, which is the most important determinant of prognosis. In benign fistulas, drainage does not involve the cerebral veins, and tinnitus or eye symptoms are often the most common forms of presentation. So-called "aggressive" or "dangerous" fistulas are characterized by retrograde cortical venous drainage, and present with bleeding in the brain, progressive neurological deficit, seizures, or intracranial hypertension.
Before recommending treatment, an imaging study of the brain is required with CT (computed tomography) scan or MRI (magnetic resonance imaging). An angiogram is also necessary, in which a catheter is inserted into an artery in the groin and dye is injected into the pertinent arteries of interest.
VIEW: Right transverse sinus DAVF supplied by middle meningeal and occipital feeding arteries.
It is important to tailor management of DAVF to each patient. Specific goals should be put forward taking into account the natural history of the lesion (which mainly depends on its venous drainage pattern), its specific anatomical features and the patient's symptoms. Most dural fistulas can be managed by endovascular means but some are more appropriately approached by surgery. Some difficult lesions need the judicious combination of endovascular techniques and surgery.
VIEW: After Onyx embolization, angiographic cure is achieved.
Traumatic direct carotid cavernous fistula