What is a stroke?
Stroke is a type of cardiovascular disease that affects the arteries leading to and within the brain. A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain becomes blocked by a clot (ischemic) or ruptures (hemorrhagic). When this happens, the area of the brain supplied by the affected blood vessel fails to work properly, and in some cases, that part of the brain dies. Depending on the severity of the stroke and the part of the brain affected, loss of function and/or death can occur.
What are the symptoms of a stroke?
The symptoms of stroke can include sudden numbness or weakness of the face, arm or leg, especially on one side of the body, confusion with speech or inability to speak normally, sudden loss of vision in one or both eyes, sudden onset of dizziness or loss of balance, trouble walking, and a sudden severe headache with no known cause. One of the problems associated with a patient’s ability to understand the symptoms of a stroke is that there is typically no acute pain similar to the chest pain associated with a heart attack. This often leads to a delay in calling 9-1-1 or seeking immediate medical attention. If you suspect that you or someone you know might be experiencing symptoms of a stroke, even if you are not sure, call 9-1-1 immediately. A stroke is a brain attack, and every minute counts.
What are the different types of stroke?
Stroke can be caused by either a clot obstructing the flow of blood to the brain (ischemic) or by a blood vessel rupturing and preventing blood flow to the brain (hemorrhagic).
Ischemic strokesmake up the majority (87%) of all strokes. An ischemic stroke occurs when a blood vessel supplying blood to the brain is obstructed, thereby cutting off the supply of oxygen and nutrients. Ischemic strokes can either be embolic (due to a clot that migrated from another part of the body) or thrombotic (due to a clot or other object that forms at the obstructed site). Both types result in decreased blood flow to vital brain cells, which can lead to irreversible cell death and long-term disability.
Hemorrhagic stroke accounts for about 13% of stroke cases. It results from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood then accumulates and compresses the surrounding brain tissue. This results in a stroke by depriving parts of the brain of blood and oxygen. There are two types of hemorrhagic stroke: intracerebral and subarachnoid.
Intracerebral hemorrhage is the most common type of hemorrhagic stroke and occurs when a blood vessel within the brain bursts and allows blood to leak within the brain. This causes an increase in pressure within the brain, which causes damage to the surrounding brain cells. Hypertension is the primary cause of this condition. Other risk factors include alcohol and drug abuse, increased age, being male and being African American.
Subarachnoid hemorrhage occurs when a blood vessel just outside of the brain ruptures, causing the area of the skull surrounding the brain to rapidly fill with blood. It is usually caused when an aneurysm swells, weakens the vessel and ruptures. Risk factors include middle age, family history, smoking, excessive alcohol use, being female and being African American.
Transient Ischemic Stroke
A Transient Ischemic Attack (TIA) is sometimes called a mini or warning stroke, and occurs when blood flow is temporarily blocked. A TIA usually lasts less than five minutes and typically resolves fairly rapidly leaving no noticeable symptoms or deficits. TIAs are a warning sign and should be taken very seriously, and can indicate that a person is at risk for a serious, debilitating stroke. TIAs are important predictors of stroke. Don't ignore these symptoms. If you are not sure whether you are suffering a TIA or stroke, do not wait to find out. Call 9-1-1 immediately. If you are suffering a stroke, prompt action can improve your treatment options. Your doctor will determine whether or not you have suffered a stroke, a TIA, or another medical problem. Act to protect yourself. Click here to view the Steps Against Recurrent Stroke (STARS) program.
How common are strokes?
Although the prevalence of stroke is higher in older adults, stroke can occur at any age and is the third leading cause of death in the United States, behind only heart disease and cancer. It is the leading cause of long-term disability in adults; patients often require full time care. Each year, about 795,000 Americans experience a new or recurrent stroke. According to the American Heart Association, stroke accounted for one of every 17 deaths in 2005, totaling more than 242,000 individuals. On average, every 40 seconds someone in the United States has a stroke, and every 3-4 minutes someone dies from a stroke.
Are age or race factors in strokes?
The risk for stroke increases with age. In fact, for every decade after age 55, the risk of stroke doubles. Additionally, the risk of stroke varies among different ethnic and racial groups. The incidence of first ever stroke among African Americans is almost double that of non-Hispanic whites. This can be attributed to the fact that African Americans have a higher incidence of stroke risk factors including high blood pressure, cigarette smoking and a higher incidence of some genetic diseases, such as diabetes and sickle cell anemia. Also, the Brain Attack Surveillance in Corpus Christi project (BASIC) demonstrated an increased incidence of stroke among Mexican Americans compared with non-Hispanic whites.
Are women affected by stroke at the same rate as men?
Each year, about 60,000 more women than men have a stroke. The difference is attributed to the higher average life expectancy in women.
What is the "Stroke Belt"?
The stroke belt, which historically has consisted of North Carolina, South Carolina, Georgia, Tennessee, Alabama, Mississippi, Arkansas, and Louisiana, is named as such because the people living in these states have a higher-than-normal stroke risk. Although still largely a mystery, researchers believe that the contributing factors for this regional phenomenon are the higher prevalence of risk factors such as high blood pressure, high cholesterol, dietary habits, the relative proportion of ethnic groups, and higher rates of smoking.
What are the risk factors for stroke?
· High blood pressure increases stroke risk four to six times
· Heart disease, especially atrial fibrillation or irregular heartbeat, can double the risk
· Sickle cell anemia
· High cholesterol
· Family history of stroke, or a previous stroke
What can you do to minimize the risks of stroke?
Stroke risk can only be assessed by a physician or other medical professional. However, individuals can help decrease their risk by maintaining a healthy blood pressure of less than 140/90, maintaining blood sugar levels as directed by their physician (if diabetic), maintaining a healthy lifestyle that includes exercise and proper diet, and smoking cessation.
Individuals with the following medically treatable risk factors should consult their physicians for appropriate treatment options:
· Atrial fibrillation
· Blockage or hardening of the arteries
· History of TIAs
· History of previous stroke
· History of previous heart attack
What should I do if I have suffered a mini stroke (TIA)?
If you think you experienced the signs and symptoms of a stroke, even if they resolve rapidly, call 9-1-1 immediately. Prompt medical attention may help prevent a future or recurring stroke. People who experience a TIA are far more likely to have a stroke than those who have never experienced a TIA.
If you have suffered these symptoms in the past and have not yet sought medical attention, do so. Talk to your doctor quickly about the symptoms. TIAs are important in predicting that a more serious stroke may occur. They can occur days, weeks or even months before a major stroke. In about half the cases, a stroke occurs within one year of the TIA.
Am I less likely to be at risk for stroke because I have never had any of the symptoms of a ministroke?
No, the majority of strokes are NOT preceded by TIAs. Talk to your doctor to understand your specific risk factors for stroke, how to prevent stroke and take time to learn the warning signs for stroke.
Does aspirin help reduce ischemic stroke risk?
While some studies have shown that taking aspirin may help protect people from stroke, and when taken within 48 hours of a stroke can reduce death rates and negative side effects, aspirin may also increase the risk of hemorrhagic stroke. It is always important to consult a physician before taking aspirin regularly.
How are strokes diagnosed?
In addition to neurological examinations by physicians, advanced imaging tests including angiography, Computerized Tomography (CT) Scans and Magnetic Resonance Imaging (MRI) are the principal tools used in diagnosing stroke.
How are strokes treated? What therapies are available?
There are generally three treatment stages for stroke: prevention, therapy immediately after the onset of stroke symptoms and post-stroke rehabilitation.
Prevention therapies are aimed toward preventing a first or recurrent stroke, and are based on treating your underlying risk factors for stroke such as hypertension, atrial fibrillation and diabetes. The ultimate goal in reducing the risk of a stroke or preventing an occurrence is to prevent the widespread formation of blood clots that can cause ischemic stroke whether or not risk factors are present. The most common types of drugs used to reduce the risk and prevent strokes are antithrombotics, antiplatelet agents and anticoagulants. Antithrombotics prevent the formation of blood clots, antiplatelet drugs prevent clotting by decreasing the activity of platelets and blood cells that contribute to the clotting property of blood and anticoagulants reduce stroke risk by reducing the clotting property of the blood.
Therapy Immediately After a Stroke, Thrombolytic Agents
Thrombolytic agents are used to treat an ongoing acute ischemic stroke caused by an artery blockage. These agents seek to dissolve the blood clot that is blocking blood flow to the brain. Current thrombolytic treatments for ischemic stroke are limited since there is only one FDA-approved product for this indication: Intravenous (IV) Tissue Plasminogen Activator (t-PA). IV t-PA is not always given because it must be used within the first three hours from stroke symptom onset and carries increased risk of bleeding.
Interventional Options, Mechanical Therapy
Mechanical therapies to remove thrombus and restore flow provide additional interventional options for ischemic stroke. The Merci Retrieval System® from Concentric Medical Inc. has been cleared by the United States Food and Drug Administration (FDA) for the removal of blood clots in the brain from patients experiencing an ischemic stroke. The FDA granted market clearance in 2004 after a review of patient data obtained in a clinical study at 25 medical centers in the United States. The MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial evaluated the device in 141 patients. The device is navigated into the brain using standard endovascular techniques. A small puncture in the groin is made to introduce the Merci Retriever® into an artery leading to the brain. Upon reaching the targeted area, the Merci Retriever is designed to restore blood flow by engaging, capturing and removing the blood clot.
Neuroprotectants are medications that protect the brain from secondary injury caused by a stroke. They are designed to repair the biochemical damage that has already been done to brain cells as a result of being deprived of blood flow. A number of studies are being performed to evaluate the effectiveness of these drugs.
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1. Stroke - Hope Through Research
2. American Heart Association. Heart Disease and Stroke Statistics — 2009 Update. Dallas, Texas: American Heart Association; 2009. ©2009, American Heart Association.
3. Peninsula Stroke Association Literature