An arteriovenous fistula is a type of vascular malformation characterized by an abnormal connection between an artery and vein in the dura (the inner lining of the skull) or brain. In this case, high-pressure arterial blood is sent directly into the low-pressure venous system. As the venous system is not designed for such high pressures, the blood backs up into the brain, preventing it from returning to the heart.
The congestion that occurs contributes to dilation of the veins and possible formation of venous aneurysms. Such aneurysms may lead to hemorrhage, seizures, headache, and neurological deficits (weakness, numbness, visual change). Sometimes, people with an arteriovenous fistula may experience a pulse like a "swooshing" noise in the head.
Occasionally, signs of swelling or dilated veins in the brain can be detected by an MRI scan. A definitive diagnosis is made by cerebral arteriography, a diagnostic tool that enables direct visualization and characterization of the fistula.
Less dangerous lesions may be simply observed and monitored. However, when there is evidence of brain swelling and venous aneurysms are present, the fistula should be treated. The main treatment method is endovascular surgery. During this procedure, the angiographer navigates a catheter into the arteries and veins in the head and precisely identifies the fistula. It is then obliterated using particles or glue. Occasionally, this treatment alone will not cure the fistula. Microsurgery (state-of-the-art surgery performed with specialized instruments and powerful microscopes) is then used to expose the fistula and disconnect the abnormal communication. At Lahey Hospital & Medical Center, we have extensive experience and worldwide recognition in treating these lesions. Our multidisciplinary cerebrovascular team evaluates each individual case. After careful consideration, an individualized treatment plan is developed.