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Diagnosis / Protected: Brain Dural Fistula

What is Brain Dural Arteriovenous Fistula?

The word “fistula” means abnormal connection between two structures that are normally not connected. An arteriovenous fistula is therefore an abnormal connection between an artery and a vein. Any part of the body can have a fistula. Normally, the brain is surrounded by a special tough cover called “dura mater”, or dura. When a fistula forms between an artery and a vein within the dura, it is called Brain Dural Fistula, or Brain Dural Arteriovenous Fistula (BDAVF).

When a fistula forms, blood from an artery under high pressure and flow goes directly into a vein, which is a low pressure and low flow structure. Even though the fistula is not directly on or within the brain, it can nevertheless lead to brain dysfunction by congesting the brain’s venous system.

What Causes Fistulas to Form?

The reason brain dural fistulas form is usually unclear. They appear to develop spontaneously. Sometimes, a patient has clear history of significant trauma or surgery in the area which later develops a fistula. In most cases, however, we have no explanation why they form, so they are sometimes called “idiopathic”, meaning without an identifiable cause. Typically, patients with fistulae are 50 years of age or older, and more often are women.

What are the Symptoms of Brain Dural Fistulas?

There are many symptoms associated with brain dural fistulas, depending on their size and location.

  • Pulsatile Tinnitus – when dural fistulas form near the ear, the patient can actually hear the sound made by the blood rushing form the arteries through the fistula into the veins. Many dural fistulas form exactly in the back of the head behind the ear, near the large brain vein called the “sigmoid sinus”. The sound ALWAYS follows the pulse; the patient can take their pulse at the wrist and correlate it on-for-one with the sound made by the fistula.

 

Of note, most patients who have pulsatile tinnitus do not have a dural fistula. In many patients with a sigmoid sinus dural fistula, the pulsatile sound heard by the patient can also be heard by someone else by placing a stethoscope on the bone behind the affected ear. If they clearly hear the sound, it is almost always due to a dural fistula.

 

  • Eye Problems – Occasionally, fistulas can form in a large venous lake behind the eye called “cavernous sinus”. These can be of two types – a direct fistula from the carotid artery to the cavernous sinus called carotid-cavernous fistula, or dural fistula where the abnormal arteriovenous connection develops between small dural branches of the internal carotid artery and the cavernous sinus. Because the cavernous sinus is normally connected to the veins that serve the eye, the fisula can produce high pressures within the eye veins and eye itself. When this happens, the eye can get large, red and painful.

 

  • Brain Hemorrhage – occasionally, fistulas result in significantly elevated venous pressures in the brain. The veins that surround the brain that are not covered by “dura” are fragile and can rupture resulting in a brain bleed. Frequently these patients may have a severe headache or collapse and require immediate medical attention.

 

  • Other Symptoms – headache, tiredness, loss of concentration, memory problems, even hallucinations, psychosis or other psychiatric problems.

How is it Diagnosed?

The diagnosis of the fistula can be made in various ways, depending on the size, location and symptoms. Imaging tests are usually performed to make a diagnosis, including:

  • Computed tomography angiography (CTA) – CTA uses a CT scanner to produce detailed views of the arteries anywhere in the body.
  • Magnetic resonance angiography (MRA) – provides similar information to that of a CTA without using ionizing radiation
  • Cerebral angiography – minimally invasive test in which a catheter is guided through an artery to the area of interest. Contrast material, dye, is injected through a tube and x-rays are taken.

IVC’s Treatment for Brain Dural Fistulas

The purpose of the treatment is to close the fistula and reduce the risk of brain hemorrhage. The primary treatment modality is catheter directed embolization. Surgery is an additional option depending on the location of the fistula and for refractory cases.

At IVC, we offer a minimally invasive treatment option, catheter directed embolization. Embolization is an endovascular procedure designed to close or plug the fistula.

For more information on embolization or to schedule an appointment for consultation, please call IVC at 503-612-0498.

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