The University of Michigan Health System’s Cerebrovascular Program is one of a select few which offer both open surgical and minimally-invasive treatment for patients with cerebral arteriovenous malformation, or cerebral AVM, a tangled web of abnormal vessels in the brain which can bleed or rupture.
The University of Michigan’s Cerebrovascular Program treats approximately 30 brain AVM patients each year. Our cutting-edge endovascular techniques and nationally-renowned surgeons bring hope to patients who, because of their age or other medical conditions, could not have been treated previously.
U-M’s Neuro Interventional suite — the first of its kind in the nation — makes it possible to both detect and repair AVMs in the same room, with a team of radiologists, neurosurgeons and other specialists working closely together. Complex patient cases are presented at a weekly multidisciplinary conference, where clinical issues and plans for treatment are reviewed by a panel of experts that ensures patients receive the optimal treatment.
What is a Cerebral Arteriovenous Malformation or AVM?
An arteriovenous malformation (AVM) is a tangled cluster of vessels in the brain in which arteries connect directly to veins with no intervening capillary bed. They can occur in any part of the brain. Brain AVMs occur in less than 1% of the population. They are more common in males than females. We currently do not know why AVMs occur. An increased prevalence has been seen in conditions such as hereditary hemorrhagic teleangiectasia.
AVMs often cause no symptoms until complications develop, such as brain hemorrhage or bleeding into the brain. Some AVMs may produce a swooshing sound that can be heard through a stethoscope. Other symptoms may include:
- Pulsing noise in head
- Headache
- Progressive weakness or numbness
Some studies have suggested that patients may suffer a seizure due to an AVM. These patients are at higher risk of hemorrhage. The studies also suggest that in the first year following a spontaneous AVM hemorrhage, the risk of bleeding again may be as high as 6% to 18%.
If bleeding occurs, symptoms may include:
- Sudden, severe headache
- Weakness or numbness
- Vision loss
- Difficulty speaking
- Inability to understand others
- Severe unsteadiness
Diagnosing an Arteriovenous Malformation or AVM of the Brain
A CAT scan of the brain is typically the first step in diagnosing an AVM. If only a small amount of blood has leaked, the test may come back negative. In these cases, your physician may do a spinal tap to see how much blood has mixed with the cerebrospinal fluid. If we diagnose an AVM, a test called a cerebral angiogram is performed. During this procedure, dye is injected into your bloodstream and x-rays are taken, which will give physicians information on how to best treat your condition
Treatment Options for Arteriovenous Malformation
Treatment depends upon the type of AVM, the symptoms it may be causing, and its location and size.
Medical Therapy for AVM
If there are no symptoms or almost none, or if an AVM is in an area of the brain that cannot be easily treated, conservative medical management may be indicated. If possible, a person with an AVM should avoid any activities that may excessively elevate blood pressure, such as heavy lifting or straining, and they should avoid blood thinners like warfarin. A person with an AVM should have regular checkups with his or her doctor.
Endovascular Therapy for AVM
It may be possible to treat part or all of the AVM by placing a small catheter inside the blood vessels that supply the AVM and blocking off the abnormal blood vessels with a variety of different materials. These include liquid tissue adhesives (glues), micro-coils, particles, and other materials used to stop blood flowing to the AVM. Endovascular therapy is usually performed prior to surgery or stereotactic radiosurgery.
Surgical Removal of an AVM
If an AVM has bled and/or is in an area that can be easily operated upon, then surgical removal may be recommended. The patient is put to sleep with anesthesia, a portion of the skull is removed, and the AVM is surgically removed. When the AVM is completely taken out, the possibility of any further bleeding should be eliminated.
Stereotactic Radiosurgery
An AVM that is not too large, but is in an area that is difficult to reach by regular surgery, may be treated by performing stereotactic radiosurgery. In this procedure a cerebral angiogram is done to localize the AVM. Focused-beam, high-energy sources are then concentrated on the brain AVM to produce direct damage to the vessels that will cause a scar and allow the AVM to “clot off.”