Embolization of Dural Arteriovenous Fistulas

Intracranial dural arteriovenous fistulas (dAVFs) are direct communications between an artery and a cerebral vein or between several arteries and a venous sinus (large veins that drain the brain). Such communications make arterial blood, of high pressure, come into direct contact with veins, which cannot withstand pressure, without passing through a network of capillaries. This communication leads to an overload of cerebral veins, which can lead to rupture of these structures and consequent cerebral hemorrhage (hemorrhagic stroke).

Dural arteriovenous fistulas constitute 10 to 15% of all cerebrovascular malformations and theoretically can occur anywhere in the dura mater (membrane that covers the brain), although they are more common behind the eyes (carotid-cavernous fistulas) or behind the eyes. ears (transverse sinus/sigmoid fistulas). Most of them are diseases acquired throughout life and the main risk factors are a history of cerebral venous thrombosis, neurosurgery and head trauma.

The endovascular treatment of intracranial dural arteriovenous fistulas (dAVFs) is currently the treatment of choice for most of these lesions and consists of the injection of an embolic agent (a kind of glue) that will fill the entire lesion, closing all the anomalous communications between the arteries and veins. This glue is injected through small catheters that are inserted into the patient’s artery or vein and are navigated until reaching the malformation.


Symptoms

  • Unruptured intracranial dural arteriovenous fistulas (that did not bleed) can cause headaches, seizures, vision deficit, pulsating ringing in the ears, dizziness, nausea, loss of arm or leg strength and even cognition change;
  • When they bleed (hemorrhagic stroke) they present as a sudden severe headache that may be associated with other symptoms such as lowered level of consciousness, mental confusion, convulsive crisis, loss of movement on one side of the body and even same coma;
  • Hemorrhagic stroke resulting from the rupture of cerebral AVFs are serious conditions that can lead the patient to death or permanent neurological sequelae.

Indications

The treatment modalities for dural arteriovenous fistulas are: conservative treatment (observation), endovascular treatment (embolization) and open surgery (microsurgery). The chosen modality will depend on the type of fistula, its location and the symptoms presented by the patient. To assess the type of fistula, its anatomical characteristics and its location, cerebral angiography is essential.

Endovascular treatment is currently the most indicated in most cases, with good results and a low rate of complications. They are performed by artery or venous route through the use of various embolic materials that will occlude anomalous communications between arteries and veins.

The main objective of treatment is to prevent bleeding from dAVFs that have not yet bled or to prevent rebleeding of those lesions that have previously hemorrhaged. Other symptoms such as pulsatile tinnitus, headache, change in strength in the upper and lower limbs are also an indication for treatment.


Procedure

Embolization of intracranial arteriovenous dural fistulas is a minimally invasive technique where it is not necessary to open the patient’s skull to treat the lesion. The surgery is performed endovascularly, that is, inside the arteries and veins. To do this, it is necessary to perform a puncture of an artery in the patient’s leg, at the level of the groin (femoral artery) or in the arm (radial or brachial artery) and take a microcatheter to the region of the lesion and then perform its occlusion.

To perform the occlusion of the AVFds, we use liquid embolic agents (a kind of glue) that will fill all the arteries and veins that form the lesion, excluding it from the cerebral blood circulation. 

There are several types of embolic agents and, in some cases, other devices, such as coils, can be used for the definitive treatment of the lesion. The choice of the most appropriate material will depend on the characteristics of the fistulas and the patient, therefore, the choice of the best embolization technique is individualized.

It is worth mentioning that because it is a minimally invasive surgery, the patient’s recovery time is shorter compared to open surgery and in cases of fistulas that did not bleed, the patient is discharged from the hospital in 24 to 48 hours after the surgery, being able to return to their activities. daily in approximately one week.

No surgical incision is needed, just a small hole in the skin that doesn’t need special dressings.


FAQ

Embolization is performed by filling the fistula with a liquid adhesive agent (a kind of glue) that will fill all the arteries and veins that form the lesion.

This liquid is injected through small catheters (microcatheters) that are inserted into the arteries of the patient’s leg (femoral artery) or arm (radial or brachial artery) and are taken by the endovascular neurosurgeon or interventional neuroradiologist to the level of the malformation.

The main risk of a dural arteriovenous fistula is its rupture, producing a cerebral hemorrhage, where the neurological complications are more or less serious depending on the location and size of the initial hemorrhage, which can lead to death of the patient or serious sequelae in certain cases.

In addition, dAVFs, depending on their location, can lead to visual loss, dizziness, pulsatile tinnitus (tinnidus), cognitive changes and loss of strength in the upper and lower limbs.

Embolization of dAVFs is performed under general anesthesia.

Dural arteriovenous fistulas constitute 10 to 15% of all cerebrovascular malformations and can theoretically occur anywhere in the brain. Most of them are diseases acquired throughout life and the main risk factors are a history of cerebral venous thrombosis, neurosurgery and head trauma.

Cerebral Angiography is the main test to determine the structure of the lesion, the affected vessels and treatment planning.