|
|
|
FREQUENTLY ASKED QUESTIONS
Q. What is a stroke?
A. Stroke is the third leading cause of death in the United States and perhaps the greatest cause of disability. It ranks as the leading cause of expenditure of health care dollars and affects about 700,000 people per year. Most strokes are caused by a blockage in a vessel (artery) supplying a part of the brain. The blockage may form at the site, or it may be a piece of clot that broke off from the heart or the artery going to the head (carotid artery). The blockage results in a lack of blood flow to that part of the brain, which stops functioning and dies if the blood vessel is not reopened. Hardening of the arteries (atherosclerosis), diabetes, high blood pressure, and diseases that cause the blood to clot too quickly are among the conditions that can lead to a stroke - the same conditions that are associated with blockages in vessels elsewhere in the body (heart, legs). The sudden appearance of weakness or numbness in a part of the body, difficulty seeing, or difficulty speaking may indicate a stroke. It is important to interpret these symptoms as a possible emergency and seek hospital care immediately as there are treatments to open blockages and reverse the consequences of stroke, but these therapies must be administered quickly. Some strokes can be treated by clot-busting drugs given through a vein if the drugs are administered within three hours of the onset of symptoms. Other strokes can be treated through endovascular techniques - by placing a catheter into the blocked vessel (like an angiogram) and injecting the clot-busting drug into the clot. This latter treatment must be performed within six hours after symptoms onset. Beyond these time limits, the damage from stroke could be permanent and therapy (reopening the vessel) may actually worsen the patient's condition by causing a bleed in the brain.
Q. Much is made of the phrase "mini-strokes." How do these differ from strokes?
A. A transient ischemic attack (TIA) is the sudden appearance of stroke symptoms (weakness, numbness, difficulty speaking and/or difficulty seeing) that lasts less than 15 minutes but goes away within a day. TIAs are often called "ministrokes" or "warning strokes." They are caused by temporary blockage of a vessel (artery) supplying part of the brain, usually by a small piece of clot that breaks up by itself. If the blockage lasts longer, damage to the brain occurs (a stroke). Even if the symptoms go away completely, changes on a CT scan or MRI scan may indicate what part of the brain was involved. It is important to determine where the clot originated as about one-third of people with a TIA eventually have a stroke, often within the next few months. If the cause of the TIA is found, it can often be treated to decrease the risk of a stroke. This may involve blood-thinning medicines (Coumadin, aspirin, Plavix, Aggrenox); better control of blood pressure, diabetes, or cholesterol; surgery to remove a blockage in a carotid artery; or opening a vessel supplying blood to the brain with a balloon catheter (angioplasty, like the angioplasties to open blocked vessels in the heart).
Q. What are the warning signs of stroke?
A. Many different neurological symptoms may accompany a stroke, including seizures, changes in alertness, and confusion. Some of the most common signs of a stroke are:
- Weakness in an arm, leg, or side of the face
- Numbness in an arm, leg, or side of the face
- Difficulty speaking or understanding speech
- Sudden change in vision
- Dizziness, loss of balance
- Sudden loss of coordination in an arm or leg
Q. What are the most common types of stroke?
A. "Ischemic" stroke is a condition caused when some part of the brain is starving for blood, and thus oxygen. It is usually caused by blockage of blood flow in a vessel, large or small. Most large blockages, which cause the most severe strokes, are caused by clots that come from the heart and float up into the brain. Others can come from large blood vessels in the neck, called the carotid arteries. Still others come from the vessels actually in the brain itself.
A "hemorrhagic" stroke is caused when a blood vessel bursts in the brain. This can be at a weak spot (usually an aneurysm), a vascular malformation (typically an arteriovenous malformation), or a small diseased vessel within the brain (typically caused by a certain type of blood vessel disease or by high blood pressure).
Q. What can be done to treat a stroke?
A. Most strokes are caused by blockage of a blood vessel supplying part of the brain, with resultant damage to that part of the brain. The blockage may be caused by a blood clot forming at the site (usually because there is atherosclerosis of the vessel, similar to the blockages that form in coronary arteries and cause heart attacks) or may be caused by clot that forms somewhere else, breaks off, and lodges in the artery (usually from the heart or the carotid artery in the neck). In the past, there was nothing that could be done to remove the blockage and restore blood flow to the brain in time to prevent permanent damage. Stroke therapy was limited to keeping the clot from getting bigger by giving blood thinning drugs and providing therapy to help the patient recover as best as possible. In the past several years, research has been directed at developing treatments to reopen the blocked vessel:
Intravenous Stroke Therapy: Many of these studies have involved the use of the "clot-busting" drugs used to treat heart attacks. In one study, it was shown that when the clot-busting drug alteplase (Activase), commonly called t-PA, was given intravenously (through a vein) within three hours after the stroke symptoms began, there was a better chance of a good recovery from the stroke than if no drug was given. Further research has shown that this treatment is more effective if the blockage is in a small artery than if it is in one of the main arteries. The major complication of this treatment is causing bleeding at the site of the stroke, which leads to more severe neurological symptoms or even death. If t-PA is given more than three hours after the beginning of symptoms, the risk of bleeding becomes too high.
Interventional Stroke Therapy: The problems with intravenous therapy are that it must be given within three hours to be safe and effective, and it does not work well when there is a large clot blocking one of the major arteries at the base of the brain. Interventional stroke therapy consists of placing a catheter in an artery (usually in the leg, similar to a heart angiogram) and positioning it in the main artery in the neck (carotid or vertebral artery) from which the blocked artery arises. A second catheter is threaded through the main catheter to the site of the blockage. Devices can be inserted through the catheter to break up the clot, but usually a clot-busting drug is given through the catheter right at the site of the clot. The advantages of this method are that it can be used to treat blockages in the larger arteries at the base of the brain, less clot-busting drug is needed (reducing the risk of bleeding), and it is safe to perform up to six hours after the onset of symptoms of the stroke. This treatment option has risks as well. As in the case of intravenous stroke therapy, interventional therapy could result in bleeding at the site of the stroke, worsening the symptoms or even resulting in death. Other disadvantages of this treatment are that it requires a specially trained doctor to perform it and therefore, it is only available at some hospitals. Also, it is still a relatively new treatment that is being refined as new clot-busting drugs and new equipment become available. This being said, a select number of doctors have performed this therapy for several years with excellent results. In many cases, their expertise has made it possible for patients who came to the hospital paralyzed in an arm or leg to make a complete recovery and go home in 2-3 days. The Interventional Stroke Therapy Outcomes Registry (INSTOR™) has been organized to collect information from these doctors performing this therapy to help further refine the technique.
Q. Who can provide interventional stroke therapy?
A. Several types of physicians may be able to provide this treatment:
- Neurointerventionist: Typically a specially trained endovascular neuroradiologist (trained in techniques involving inserting catheters into the vessels to be treated); all of these specialists are capable of performing emergency stroke therapy
- Neurologist: Very few are specially trained in endovascular techniques
- Neurosurgeon: Only a few are trained in endovascular techniques
- Interventional radiologist: All are trained in endovascular techniques, but only a few are specially trained in neurointervention
Q. What is the standard of care for stroke in the United States today (what treatment do most patients receive)?
A. Even today, the majority of stroke patients are treated as they were in the past. Care is aimed at preventing complications and providing therapy to help the patient recover as best as possible. Tests are usually performed to determine the cause of the stroke and treatment to prevent another stroke may be considered. There are many reasons why patients do not receive acute intravenous or interventional therapy. Often, patients do not come to the hospital in time to be treated because they don't recognize they are experiencing a stroke or they do not know that there is a treatment available. Other patients are not able to receive t-PA or other clot-busting drugs because of other medical conditions that make this therapy too risky (conditions such as recent surgery, bleeding problems, history of another recent stroke or bleed in the head). Although many hospitals offer intravenous therapy, the number of hospitals that are able to offer interventional therapy is very limited. In order to address these issues, efforts are being made to educate the public about the emergency nature of stroke. The first message is that stroke is a brain attack with consequences as or more severe than a heart attack and the second message is that treatment is available if the patient seeks emergency care within a certain time window. Physicians are also being educated on stroke therapies available in their communities. Second, numerous forces in local communities and on the national front are coming together to increase the number of hospitals equipped and trained to offer all forms of stroke therapy as well as the number of doctors trained in endovascular techniques. Finally, the scientific and research arms of the medical establishment are working hard to further enhance current techniques. For example, the development of new drugs may in the future make it possible to offer therapy to patients more than six hours after symptoms begin. These new developments may also allow the treatment of patients who are considered too risky to treat today.
Q. What is intracranial atherosclerosis?
A. Atherosclerosis is narrowing of the arteries (stenosis) caused by buildup of material in the walls of the arteries ("plaque"). This plaque can be smooth or irregular. Smooth plaque causes symptoms when the artery becomes so narrow that an insufficient supply of blood is getting through it. Irregular ("ulcerated") plaque can cause symptoms because of the degree of stenosis; it can also cause symptoms because pieces of the plaque itself or clot that forms on the plaque break off and block off smaller arteries downstream. When such narrowing of the arteries occurs in the vessels in the head, the condition is called intracranial atherosclerosis. This same disease can also cause stenosis in the arteries of the legs, heart, and other parts of the body. High blood pressure, diabetes, cigarette smoking, and high cholesterol are all associated with the formation of plaque.
Most strokes are caused by a blockage in a vessel (artery) supplying a part of the brain. The blockage results in insufficient blood flow to that part of the brain, which stops functioning and dies if the blood vessel is not reopened. Intracranial atherosclerosis is a significant cause of strokes. If the blockage is temporary, a transient ischemic episode (TIA or "ministroke") can occur. Following a TIA, up to one-third of patients suffer a subsequent stroke, often within months. This risk is even higher when only those TIAs and strokes caused by intracranial atherosclerosis are considered.
Q. How is intracranial atherosclerosis diagnosed?
A. A stenosis in an artery in the head is usually discovered when it becomes severe enough to cause symptoms, or when there is more than one stenosis and another stenosis causes symptoms. Tests that are sometimes used to identify these stenoses include special forms of computed tomography (CT) scans or magnetic resonance imaging (MRI) scans called CT and MR angiography. Whereas these tests focus on the blood vessels, most of these stenoses are identified by an angiogram. A cerebral angiogram is the same type of procedure as a coronary angiogram (or cardiac catheterization), and is performed by placing a needle into an artery, usually at the groin, but sometimes in an arm, inserting a thin flexible tube called a catheter into the artery using the needle as a guide and advancing the catheter into the arteries supplying the brain, using x-rays for guidance. A special kind of dye called contrast is injected through the catheter while x-rays of the arteries are taken.
Q. What can be done to treat intracranial atherosclerosis?
A. Treatment of intracranial atherosclerosis, like treatment of atherosclerosis elsewhere in the body, has many components. Treating the conditions that contribute to atherosclerosis (lowering cholesterol, quitting smoking, controlling diabetes, lowering blood pressure, exercise, etc.) is key. Medical management is also important. In addition to medications aimed at treating one of the contributing conditions, aspirin and other drugs that keep the platelets (a type of blood cell) from sticking together and adhering to the plaques are an important part of medical therapy.
Once a stenosis is severe enough to cause symptoms (or under other special circumstances), a procedure called angioplasty may be performed to open the artery. This is like angioplasties performed on coronary arteries to treat or prevent heart attacks. A tiny catheter with a balloon on the end is steered all the way up to and across the stenosis and slowly inflated to stretch the artery back open. Sometimes a stent (a small metal mesh tube that props the artery open) is placed, depending on the location of the stenosis and how easily it can be stretched by the balloon alone. The goal of angioplasty (with or without stent placement) is to open the artery enough to improve blood flow and prevent further symptoms.
Q. Who treats intracranial atherosclerosis?
A. Prevention and medical management are usually handled by physicians such as neurologists (specialists in conditions affecting the nervous system), internists, or cardiologists (specialists in cardiovascular diseases).
If angioplasty (with or without stenting) is indicated, several types of physicians may be able to provide this treatment. These include:
- Neurointerventionist
- Typically a specially trained endovascular neuroradiologist (trained in techniques involving inserting catheters into the vessels to be treated); most of these specialists are capable of performing intracranial angioplasty
- Neurologist
- Very few are specially trained in endovascular techniques
- Neurosurgeon
- Only a few are trained in endovascular techniques
- Interventional radiologist
- All are trained in endovascular techniques, but only a few are specially trained in neurointervention
Q. What is the standard of care for intracranial atherosclerosis in the United States today (what treatment do most patients receive)?
A. Most patients receive preventative care and medical management. There are many reasons why angioplasty (with or without stenting) may not be considered. A few of these are:
- The stenosis may not be severe enough
- It may not be possible to reach the stenosis with a balloon or stent
- The patient may have other medical conditions making the procedure too risky
In addition, angioplasty may need to be delayed if the patient has recently suffered a stroke because strong medicines to prevent blood clotting are administered during and just after the procedure. These medicines could cause hemorrhage into a fresh stroke, making the situation much worse.
One of the major reasons that intracranial angioplasty may not be performed is that only a limited number of hospitals have a specialist that is trained to perform this procedure.
|
|
