Dural Arteriovenous Fistula
A dural arteriovenous fistula (DAVF), also called a dural arteriovenous malformation (dural AVM), is an atypical connection between blood vessels in the dura. When necessary, surgical treatment for DAVF most commonly takes the form of endovascular embolization, microsurgical resection, or stereotactic radiosurgery.
The blood vessels affected in a DAVF are arteries and veins. Ordinarily, capillaries take in high-pressure blood from arteries, deliver the blood’s oxygen to tissues and send the blood into the veins under much lower pressure. But in a DAVF, capillaries are absent, and the arteries and veins are connected directly. Without capillaries, high-pressure arterial blood rushes directly into veins, causing the venous system to experience greater than normal pressure.
Dural arteriovenous fistulas are complex lesions and should be managed at major centers with specialists highly trained in their treatment. At Columbia University Irving Medical Center/NewYork-Presbyterian Hospital, our neurosurgeons are experienced in evaluating DAVFs and in treating them surgically when necessary.
Patients with dural arteriovenous fistulas typically experience a bruit, a rumbling noise in one ear that follows the heartbeat.
Other symptoms of dural AVFs include headache, ringing in the ears, visual problems, stroke-like symptoms, and rarely, dementia-like symptoms.
Dural AVFs may hemorrhage—a medical emergency. Symptoms of hemorrhage may include severe headache, sudden confusion, and sudden weakness or numbness (especially on only one side of the body).
While screening tests like MRI and CT scans may be the initial test that raises the suspicion of a DAVF, an angiogram (also called an arteriogram) is the most important diagnostic tool for DAVFs. During an angiogram, a dye that can be seen on X-ray is injected into the bloodstream. Then a specialist uses a series of X-rays to examine the blood flow in the brain and its covering. The angiogram provides essential information about both the location and the structure of the malformation.
DAVFs may arise as a result of trauma, infection or surgery. Revascularization that develops in the presence of a clot obstructing flow in an existing vessel can also lead to DAVF.
Some DAVFs—those that do not cause symptoms and do not appear likely to hemorrhage—can be monitored without treatment.
The current treatment of choice for other DAVFs is endovascular embolization. To perform this procedure, a specialist inserts a catheter through an artery in the groin and then guides the catheter through the circulatory system to the site of the DAVF. Once in position, the catheter delivers a kind of “glue.” The “glue” embolizes the abnormal passageway, blocking the abnormal connection often permanently curing the fistula.
Sometimes microsurgical resection, in which a surgeon completely removes the abnormal vessels, is necessary. When possible, the DAVF lesion is embolized before it is removed. But in cases in which the risk of hemorrhage is high, or in which the catheter cannot reach the DAVF, microsurgical resection may be used alone.
Stereotactic radiosurgery also may be used in specific cases.