What are aneurysms, "strokes" and "TIA's"?

Like all parts of the body, the brain is composed of living cells that require a blood supply to provide oxygen and nutrients. The term stroke includes any disease process that kills cells in any region of the brain. A stroke can cause different symptoms, depending on which part of the brain is injured. Some regions of the brain can die and yet the patient will have no symptoms at all. Other areas of the brain are more important. A tiny stroke in these locations can cause severe disabilities, including difficulty with speech, blindness, paralysis or even death.

Blockage or rupture of blood vessels supplying parts of the brain cause most strokes. When a blood vessel becomes blocked, the part of the brain served by that vessel doesn't receive enough oxygen containing blood. If the blockage lasts long enough, brain cells die and a stroke results. Doctors call this an ischemic infarct. However, if the blockage is temporary, the blood supply may not be interrupted long enough to cause cell death. This temporary blockage causes short-term symptoms usually lasting only minutes or hours. Called mini-strokes or TIA's (short for transient ischemic attacks), these attacks are a sign of a serious problem that can lead to a permanent stroke if the problem isn't treated.

Even if some cells are permanently damaged in a stroke, other cells in the surrounding area sometimes take on the function of the dead cells. This is why some stroke patients eventually recover some or all of their abilities.

Hemorrhage is the other common cause of a stroke. Hemorrhage refers to bleeding into the brain, usually because of a problem with a blood vessel. The problem is often an aneurysm.

What is an aneurysm?

An aneurysm is an abnormal bulging outward of an artery's wall. The wall may smoothly bulge outward in all directions. It may form a sac arising from one wall. Aneurysms can occur in any artery of the body, but only those affecting the arteries supplying the brain can cause a stroke. Aneurysms cause problems in several different ways. If the aneurysm ruptures, blood flows into the brain or into a space closely surrounding the brain called the subarachnoid space. It has been estimated that in the U.S. between 12,000 and 28,000 people suffer such "aneurysmal subarachnoid hemorrhages" every year. A patient with a subarachnoid hemorrhage usually suffers "the worst headache of his/her life" followed by nausea and vomiting. Double vision, neck stiffness and loss of consciousness are also common.

Aneurysmal subarachnoid hemorrhage is a medical emergency. 10-15% of these patients will die before reaching the hospital. Over half will die within the first thirty days after the hemorrhage. Of survivors, approximately half will suffer a permanent stroke. Strokes caused by subarachnoid hemorrhage often occur one to two weeks after the hemorrhage itself. This happens because the blood from the hemorrhage irritates the blood vessels on the surface of the brain, causing them to close. Vessels in vasospasm have difficulty supplying the brain with enough blood. Treatment of patients with ruptured aneurysms usually consists of trying to prevent vasospasm, trying to help vessels in vasospasm maintain blood flow to the brain, and blocking off the aneurysm so that it will not bleed again.

Less commonly, aneurysms cause problems not related to bleeding. An aneurysm can form a blood clot within it, which can break away and be carried downstream until it obstructs a small arterial branch, causing either a stroke or mini-stroke. An aneurysm can also press against nerves (resulting in paralysis or abnormal sensation of an eye or the face) or the adjacent brain (resulting in seizures). Your doctor may suggest an arteriogram if an aneurysm is suspected.


What is an arteriogram?

An arteriogram (also called an angiogram) is a diagnostic study, usually performed by a Radiologist, to assist in determining the cause of a stroke and treatment alternatives. A very thin, flexible tube called a catheter is introduced into an artery (usually at the groin) and then steered through the blood vessels of the body to the artery involved by the aneurysm. This is performed in an angiography suite, using x-rays to see the position of the catheter. A liquid containing water and iodine salts (contrast), which can be seen on x-rays, is injected through the catheter and x-ray images are taken. This provides detailed pictures of the area, size and shape of the aneurysm as well as a map of the arterial tree from which it arises. With this information, a decision will be made by you and your doctors to determine the most appropriate method as to how that particular aneurysm should he treated.


How are aneurysms treated?

Aneurysms may be treated from outside the blood vessel using surgical techniques or from inside the blood vessel using endovascular techniques.

The surgical method is an invasive procedure and requires an incision. The surgeon places a clip across the neck of the aneurysm, preventing arterial blood from entering. If there is a clot in the aneurysm, the clip also prevents the clot from entering the artery and possibly causing a stroke. Surgery is the most common treatment for aneurysms.

In contrast to surgery, endovascular treatment of an aneurysm is performed in the angiography suite with a catheter similar to that used during the arteriogram. Through the catheter, the aneurysm is packed with material that doesn't allow arterial blood to flow into it. This technique is called embolization. Materials used for aneurysm embolization include platinum coils.

Sometimes the size, shape or location of an aneurysm makes both surgical clipping and endovascular embolization impossible. Such cases may require your doctor to block off (occlude) the artery itself. This is generally performed surgically or with endovascular methods. In either approach, this is performed following determination that permanent occlusion of the artery won't cause other problems.


Who performs endovascular embolization procedures?

The endovascular treatment of aneurysms is a relatively new procedure and requires specialized training. Most endovascular therapists are neuroradiologists or neurosurgeons who have completed additional training, ranging from one to three years, in endovascular techniques.


What is the endovascular embolization procedure like?

The patient may either already be in the hospital, may arrive the night before or morning of the embolization. The patient will be asked not to eat anything after midnight the night before the procedure. Aneurysm embolization procedures can be performed under general anesthesia or under light sedation. 

After the procedure is completed, the patient will need to remain immobile, lying flat on his/her back for up to eight hours. This rest period allows the needle incision in the groin artery to heal. The patient usually remains under observation in the hospital for an additional day before returning home. Longer stays are common, depending on the patient's condition.


Will all symptoms go away after the aneurysm is embolized? Will any other visits to the doctor be necessary?

It is important to understand that the embolization procedure does not repair areas of the brain already injured by stroke. It is performed to prevent the aneurysm from causing injury to other areas. A patient who has had a severe stroke may continue to need intensive medical care even after the aneurysm has been embolized. Most patients will also need to return for follow-up arteriogram, usually performed several months after the embolization procedure. This is to ensure the aneurysm is completely embolized.  Occasionally, these follow-up studies show a second or third embolization procedure is required to completely cure the aneurysm.


How do you get aneurysms? Are they hereditary? Should family members be tested?

Aneurysms are usually the result of abnormal blood flow patterns within an artery. As the blood pulsates against an area of the vessel wall, the wall begins to bulge outwards. This process usually takes years. Aneurysms in children are extremely rare. High blood pressure can contribute to the formation of some aneurysms. Diseases which weaken arterial walls are uncommon causes of aneurysms, The majority of aneurysms are isolated problems not associated with disease. They are not hereditary and family members are not at increased risk.