Dural Arteriovenous Fistulae

Dural arteriovenous fistulae are abnormal connections between the arteries in the head and the dural sinuses-the large veins draining the brain that are found in the covering of the brain. The term “dural” refers to the membrane that surrounds the brain. “Fistula” refers to an abnormal connection, and “arteriovenous” represents the artery-vein connection.

The arteries in the brain and the sinuses are directly connected, without any vessels in between them. Fistulae result from several kinds of abnormalities including:

  • An injury or trauma
  • An infection, such as sinus infections or mastoiditis (an inflammation of the area of the temporal bone behind the ear)
  • Blood clotting in the vein. The fistula forms as a result of the body trying to open the vein.

Neurological symptoms or headaches, particularly if the fistulae cause an increase in the pressure in the veins draining the brain.

Symptoms of fistula may vary. Some people with fistulae may complain of a pulsating or humming sound in one ear. There may also be neurological symptoms or headaches, particularly if the fistulae cause an increase in the pressure in the veins draining the brain. People may also develop glaucoma.

When a fistula is present, it can also cause the vein to rupture, which will result in hemorrhage or bleeding in or around the brain. This is a serious complication that warrants medical treatment.

Before determining what type of treatment to recommend, a physician is likely to order a scan to assist with diagnosing the fistulae. The patient may undergo CT (computer tomography) scan or MRI (magnetic resonance imaging). An angiography may also be recommended, in which a catheter is inserted into an artery and guided to the fistulae through the use of x-ray technology. Dye is injected into the affected arteries so that they can be viewed and the fistulae can be observed.

The type of treatment for a dural fistula depends on the vessels involved, and may include combinations of treatment. Some of the available options include surgery or radiation therapy. Treatment to unblock arteries and/or veins may also be required.

In some cases, an angiogram-like procedure known as embolization is recommended. In this procedure, a catheter is inserted into leg and guided into the affected blood vessels using x-ray technology. Material is then injected to block off the vessels.

The embolization procedure from start to finish
Prior to undergoing embolization, patients are expected to sign a consent form and will have the opportunity to have questions answered. The anesthesiologist will administer medications and fluids through the use of an intravenous line (IV) into a vein in the hand or arm. He or she will also administer general anesthesia so that the patient will be completely asleep for the procedure. Blood pressure will be monitored through an A-Line, a thin flexible tube or catheter placed in an artery in your wrist. An electrocardiogram (EKG) will monitor heart rate and rhythm as well as oxygen levels. A specific type of catheter known as a Foley will be placed in the bladder to allow urine to drain.

Once the procedure is complete, the patient will be transferred from the operating room to either the Surgical Intensive Care Unit (SICU) or the Post-Anesthesia Care Unit (PACU). Here, a heart monitor will closely monitor vital signs. This machine is very sensitive and often sounds inadvertently; this is not cause for alarm. The nursing staff will assist in changing positions, but bed rest is required. Eventually, the patient can look forward to a normal diet and transfer to a room on a surgical floor. The Foley catheter will also be removed prior to leaving the bed for the first time.

Patients are expected to keep the leg that underwent surgery straight for several hours and a tube may remain in place at the puncture sight for several days. Once it is removed, the physician will apply pressure for about 20 minutes to prevent bleeding, and a device may be used to seal the puncture.