From the Cerebrovascular Imaging and Interventions Committee of the American Heart Association Cardiovascular Radiology Council
Randall T. Higashida, M.D., Chair
An ischemic stroke is ANY damage to the brain caused by lack of blood flow in the brain blood vessels or in major arteries leading to the brain. This usually results in temporary or permanent loss of one or more normal functions of the body. A hemorrhagic stroke is due to bleeding into the brain causing damage.
This angiogram shows normal
In this angiogram, many normal
Strokes are very common. In the United States, someone suffers a stroke every 45 seconds. About 700,000 new and recurrent strokes occur each year. Strokes affect one in five people during their lifetime.
After heart disease and all forms of cancer, stroke is the third-leading cause of death in the United States, Canada, Europe and Japan.
Estimates are that strokes cost about $50 billion a year in the United States. Over $30 billion is spent on hospitalization, medical equipment and rehabilitation. (Strokes are a leading cause of adult disability, often requiring in-patient rehabilitation.) Lost productivity from stroke survivors being unable to return to their jobs accounts for nearly $20 billion.
There are two types of risk factors - those you can't control and those you can.
Factors you can't control:
Factors you can control:
One of three things can happen:
More than 4.6 million people in the United States have some disability from a stroke. Rehabilitation may benefit stroke survivors, but the underlying cause for the stroke still needs to be treated.
There are two major types of stroke. The first is caused by blocked blood flow and oxygen to the brain. This is called an "ischemic" stroke. They account for nearly 80 percent of all strokes. The second type is caused by bleeding into or around the brain. This is called a "hemorrhagic" stroke. Hemorrhagic strokes account for about 20 percent of strokes.
An ischemic stroke is caused when blood flow is blocked either by a blood clot that forms in the heart or on a hardened fatty buildup (atherosclerotic plaque) in one of the larger blood vessels going to the brain. These vessels are the carotid artery in the front of the brain or the vertebral and basilar arteries in the back of the brain.
What causes an ischemic stroke?
A blood clot that travels into the brain is called a "cerebral embolus." A clot that builds up in the brain and ultimately blocks this blood vessel is called a "cerebral thrombosis."
What causes a hemorrhagic stroke?
A common cause is a ruptured "cerebral aneurysm." This is a weakened section of a brain artery that has ballooned out and burst. Other causes are:
A TIA occurs when a person briefly experiences stroke symptoms that last from several seconds to minutes, and then go away. There's usually no permanent brain damage. However, a person experiencing a TIA should be examined immediately, because a TIA is often a sign that a major stroke will occur. Never ignore the warning signs of a stroke. A TIA is a very important warning sign!
The most common warning signs of a stroke are:
The immediate response to experiencing or witnessing any of the symptoms outlined above is to call 9-1-1. The patient or their guardian should ask to be taken to the closest hospital or emergency room that specializes in stroke treatment. Staff at some hospitals may not be adequately prepared to recognize and treat stroke. A person having a stroke needs to be evaluated quickly and treated before it's too late!
The longer the delay for evaluation and treatment, the more likely the damage will be irreversible and permanent and the higher the chances of dying or experiencing severe disability from an acute stroke. Intravenous tPA (tissue Plasminogen Activator) is an FDA approved drug that improves the likelihood of partial or complete recovery for certain strokes. This drug can only be given to patients who qualify for this therapy and must be administered by properly trained personnel within 3 hours of the onset of certain strokes.
With a stroke, time is brain. The longer a person waits, the more likely the brain damage will be irreversible. Intravenous tPA (tissue Plasminogen Activator), the only FDA-approved drug treatment for acute, ischemic stroke, has not been shown to be effective after three hours. However, depending upon the severity of symptoms, a stroke patient may be eligible for other types of treatments. Evidence shows that placing a small tube (catheter) directly into the blood clot within the brain and giving a clot-dissolving drug within six hours may also improve outcome compared to no treatment. Depending upon a patient's overall medical condition and specific stroke type, they may be eligible for this treatment. These treatments are more specialized and require special facilities and physicians who are trained to perform these procedures.
Currently, a large number of clinical studies are looking at ways to improve the outcome of patients having a stroke. Most of these treatments, however, need to be started within six hours from stroke onset. This time factor makes it very important to seek medical attention as quickly as possible and at a hospital that specializes in stroke treatment.
One or more of the following tests may be required to accurately diagnose a stroke:
Ischemic strokes are caused by blood clots that block normal flow in brain blood vessels. If a person can be treated within three hours of their first symptoms, they benefit from intravenous tPA given to dissolve the blood clot. It has been shown that chances of complete recovery improve by 30 percent when tPA is used soon enough on the correct types of stroke.
If a stroke is caused by an atherosclerotic plaque blocking a blood vessel, the patient may need a procedure to open up the vessel. If the blocked blood vessel is in the neck, they may need surgery (carotid endarterectomy) to open it.
However, if the blood vessel isn't in an area suitable for surgery, a procedure called balloon angioplasty and stent placement may be more appropriate. This procedure involves going inside the blood vessel with a small balloon, and inflating the balloon to open and dilate the blocked artery. In some cases, a small metallic tube called a "stent" is inserted to help keep the blood vessel open.
Many hemorrhagic strokes are caused by bleeding from a ruptured intracranial aneurysm. An aneurysm should be treated as quickly as possible, since there is a very high chance of repeated bleeding.
Aneurysm that has not ruptured
More bleeding results in further brain injury or possibly death.
An aneurysm can be treated either by direct surgical clipping by a neurosurgeon or by treatment from inside the blood vessels (similar to an angiogram) by an interventional neuroradiologist.
Using X-ray guidance, the interventional neuroradiologist threads a catheter through the brain blood vessels directly into the aneurysm. Very soft, tiny platinum coils can then be carefully placed into the aneurysm to prevent more bleeding. Depending upon the size and location of the aneurysm, and the patient's condition, either surgical clipping or this endovascular coil treatment may be recommended.
Sometimes bleeding may be due to other causes, including an arteriovenous malformation. This occurs when, tiny abnormal blood vessels have become weakened and burst. An angiogram is usually performed to identify the cause of bleeding into the brain.
Different kinds of specialists are available depending on the type of stroke being treated.
If the stroke is due to a blockage from plaque, it may be possible to open up the artery with balloon angioplasty to dilate the artery and possibly place a small metal stent across the blockage to keep the blood vessel open.
If the stroke is due to an aneurysm or vascular malformation in the brain, it may be possible to treat the condition by placing small coils and other materials into the bleeding site to prevent more bleeding.
Interventional neuroradiologist/endovascular neurosurgeons perform these delicate operations in the brain to treat acute strokes. These doctors have had additional specialized training. That training is required in order to navigate within the delicate brain blood vessels to open up blocked arteries or close off weakened areas of blood vessels (aneurysms) that may have ruptured and bled.
Not every hospital has interventional neuroradiologists with these capabilities, so it is important that a patient who has stroke symptoms be taken to a facility that has these capabilities to maximize their chances for successful treatment.
For more information, contact the American Stroke Association, a division of the American Heart Association, at 1-888-4-STROKE (1-888-478-7653) or visit StrokeAssociation.org.