What are brain aneurysms and AVM's?
A brain aneurysm is an abnormal weak area in an artery in the brain that causes the vessel to bulge outward. It is estimated that up to one in 15 people in the United States will develop a brain aneurysm during their lifetime.
Brain aneurysms are often discovered when they rupture, causing bleeding into the brain or the space closely surrounding the brain called the subarachnoid space, causing a subarachnoid hemorrhage. The main goals of treatment once an aneurysm has ruptured are to stop the bleeding and potential permanent brain damage and to reduce the risk of recurrence. Brain aneurysms which have not ruptured are sometimes treated to prevent rupture.
An AVM is an abnormal connection between the arteries and the veins in the brain that results in a tangle of vessels. An AVM is typically congenital, meaning it dates to birth. You may not know you have a brain AVM until you experience symptoms, such as headaches or a seizure. In serious cases, the blood vessels rupture, causing bleeding in the brain (hemorrhage). Once diagnosed, a brain AVM can often be treated successfully.
The most common tests that are used to diagnose aneurysm and AVMs are a cerebral angiogram or CT angiogram.
Cerebral Angiography (Angiogram): A thin tube is inserted into an artery in the groin. This thin tube is threaded up to the blood vessels from the groin toward the brain. Dye is injected into the blood vessels of the brain and pictures are taken. An AVM will show up as a tangle of blood vessels. Doctors are able to see the exact location and size of the AVM. An aneurysm will show up as a bubble bulging out on the vessel. This is the most accurate test.
CT Angiogram: An IV (special tube in the vein) is placed and contrast dye is injected into the vein. CT scans are used to image the brain and vessels. CTA is a useful way of screening for aneurysms and AVM's because it is safer and much less time-consuming than catheter angiography. There is also less discomfort because contrast material is injected into an arm vein rather than into a large artery in the groin.
How are aneurysms and AVM's treated?
Not all aneurysms and AVM's require treatment. Some are small enough that the risk of rupture is low. For those that require treatment, aneurysms can be treated by a neurosurgeon that performs a brain surgery to place a clip across the aneurysm and stop blood from going into it. To get to the aneurysm, surgeons must first remove a section of the skull, a procedure called a craniotomy. The surgeon then spreads the brain tissue apart and places a tiny metal clip to stop blood flow into the aneurysm. After clipping the aneurysm, the bone is secured in its original place, and the wound is closed.
Another option is coil embolization to treat the aneurysm from the inside. The coiling treatment is done by a specialized neurointerventional radiologist or a neurosurgeon with endovascular training. The coiling procedure involves insertion of a catheter (small plastic tube) into the artery in the patient's leg and navigating it through the vascular system and into the aneurysm. Tiny platinum coils are threaded through the catheter and placed into the aneurysm, (like stuffing a trash can) blocking blood flow into the aneurysm and preventing rupture. The coils are made of platinum so they are visible on X-ray and flexible enough to conform to the aneurysm shape. This endovascular coiling, or filling, of the aneurysm is called embolization and can be performed under general anesthesia or light sedation. More than 125,000 patients worldwide have been treated with detachable platinum coils.
Treatment for AVM's employ some of the same techniques and are based on that patient’s history, symptoms, and anatomy of the AVM including its size, feeding arteries, draining veins, and location within the brain. Treatments include: endovascular embolization (closure of the AVM from within the blood vessels), brain surgery to remove the AVM, radiosurgery (special conformal beam of radiation), or a combination of techniques.
Your doctors will determine which treatment is best for you based on the aneurysm or AVM location, size and type.