What is stroke? [Index]
For the human brain to function at peak levels, blood must flow through its many vessels. If blood flow is obstructed to any part, the brain loses its energy supply and becomes injured. If blood is obstructed for more than several minutes, the brain cells' injury becomes permanent and tissue dies in the affected region. The loss or alteration of bodily function that results from an insufficient supply of blood to part of the brain is called a stroke.
Stroke is the third leading cause of death in the United States after diseases of the heart and all forms of cancer. About 600,000 Americans have strokes each year. Someone has a stroke every 53 seconds.
Someone dies of a stroke every 3.3 minutes.
Stroke is also one of the leading causes of serious, long-term disability and accounts for more than half of all patients hospitalized for neurological disease that strikes quickly.
About 4.5 million stroke survivors are alive today. (2.2 million are male; 2.3 million are female.)
Stroke costs the United States $30 to $40 billion per year.
What are the types of stroke? [Index]
If we consider an isolated blood vessel, blood flow to the brain tissue can be hampered in two ways:
1. the vessel clogs within (ischemic stroke)
2. the vessel ruptures, causing blood to leak into the brain (hemorrhagic stroke)
Ischemic stroke accounts for about 83 percent of all cases. It results from an obstruction, typically a blood clot. These clots are called a cerebral thrombus or cerebral embolism.
Hemorrhagic stroke accounts for about 17 percent of stroke cases. It results from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. The two types of hemorrhagic strokes are intracerebral hemorrhage or subarachnoid hemorrhage.
Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls. This condition is called atherosclerosis. These fatty deposits can cause two types of obstruction:
Cerebral thrombosis refers to a thrombus (blood clot) that develops at the clogged part of the vessel.
Cerebral embolism refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain's blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain.
Hemorrhagic stroke occurs when a weakened blood vessel ruptures. Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).
An aneurysm is a ballooning of a weakened region of a blood vessel. If left untreated, the aneurysm continues to weaken until it ruptures and bleeds into the brain.
An arteriovenous malformation (AVM) is a cluster of abnormally formed blood vessels. Any one of these vessels can rupture, also causing bleeding into the brain.
Transient ischemic attacks, also called TIAs, are minor or warning strokes. In a TIA, conditions indicative of an ischemic stroke are present and the typical stroke warning signs develop. However, the obstruction (blood clot) occurs for a short time and tends to resolve itself through normal mechanisms.
Even though the symptoms disappear after a short time, TIAs are strong indicators of a possible major stroke. Steps should be taken immediately to prevent a stroke.
What are the effects of stroke? [Index]
The brain is an extremely complex organ that controls various body functions. If a stroke occurs and blood flow can't reach the region that controls a particular body function, that part of the body won't work as it should.
If the stroke occurs toward the back of the brain, for instance, it's likely that some disability involving vision will result. The effects of a stroke depend primarily on the location of the obstruction and the extent of brain tissue affected.
|The effects of a stroke depend on a number of factors including the location of the obstruction and how much brain tissue is affected. However, because one side of the brain controls the opposite side of the body, a stroke affecting one side will result in neurological complications on the side of the body it affects.|
If the stroke occurs in the left side of the brain, the right side of the body (and the left side of the face) will be affected, producing some or all of the following:
If the stroke occurs in the brain's right side, the left side of the body (and the right side of the face) will be affected, which could produce any or all of the following:
What are the risk factors of stroke? [Index]
The American Stroke Association has identified several factors that increase the risk of stroke. The more risk factors a person has, the greater the chance that he or she will have a stroke. Some of these you can't control, such as increasing age, family health history, race and gender. But you can change, treat or modify most other risk factors to lower your risk. Factors resulting from lifestyle or environment can be modified with a healthcare provider's help.
Increasing age -- The chance of having a stroke more than doubles for each decade of life after age 55. While stroke is common among the elderly, many people under 65 also have strokes.
Sex -- The latest data show that, overall, the incidence and prevalence of stroke are about equal for men and women. However, at all ages, more women then men die of stroke.
Heredity (family history) and race -- The chance of stroke is greater in people who have a family history of stroke. African Americans have a much higher risk of disability and death from a stroke than whites, in part because blacks have a greater incidence of high blood pressure, a major stroke risk factor.
Prior stroke -- The risk of stroke for someone who has already had one is many times that of a person who has not.
High blood pressure -- High blood pressure is the most important risk factor for stroke. In fact, stroke risk varies directly with blood pressure. Many people believe the effective treatment of high blood pressure is a key reason for the accelerated decline in the death rates for stroke.
Cigarette smoking -- In recent years, studies have shown cigarette smoking to be an important risk factor for stroke. The nicotine and carbon monoxide in cigarette smoke damage the cardiovascular system in many ways. The use of oral contraceptives combined with cigarette smoking greatly increases stroke risk.
Diabetes mellitus -- Diabetes is an independent risk factor for stroke and is strongly correlated with high blood pressure. While diabetes is treatable, having it increases a person's risk of stroke. People with diabetes often also have high cholesterol and are overweight, increasing their risk even more.
Carotid artery disease -- The carotid arteries in your neck supply blood to your brain. A carotid artery damaged by atherosclerosis (a fatty buildup of plaque in the artery wall) may become blocked by a blood clot, which may result in a stroke. If you have a diseased carotid artery, your healthcare provider may hear an abnormal sound in your neck, called a bruit (BROO ee), when listening with a stethoscope.
Heart disease -- People with heart problems have more than twice the risk of stroke as those whose hearts work normally. Atrial fibrillation (the rapid, uncoordinated beating of the heart's upper chambers) in particular raises the risk for stroke. Heart attack is also the major cause of death among stroke survivors.
Transient ischemic attacks (TIAs) -- TIAs are "mini strokes" that produce stroke-like symptoms but no lasting damage. They are strong predictors of stroke. A person who's had one or more TIAs is almost 10 times more likely to have a stroke than someone of the same age and sex who hasn't.
High red blood cell count -- A moderate or marked increase in the red blood cell count is a risk factor for stroke. The reason is that more red blood cells thicken the blood and make clots more likely.
What other factors can affect the risk of stroke? [Index]
How are heart disease risk factors related to stroke? [Index]
Other risk factors are secondary risk factors for stroke. They affect the risk of stroke indirectly by increasing the risk of heart disease:
High blood cholesterol and lipids
Obesity or overweight
Know the warning signs of stroke[Index]
If you notice one or more of these signs in another person or yourself, don't wait. Call 9-1-1 or your local emergency medical services number immediately and get the person to a hospital right away! Treatment can be more effective if given quickly. Every second counts!
The signs are:
Not all of these signs occur with every stroke. Sometimes they go away and return. If some occur, get help fast. If you notice one or more of these signs in another person, don't wait. Call 9-1-1 and get them to a hospital right away!
What is a TIA (transient ischemic attack)?[Index]
A TIA is a "mini-stroke" with the same signs as a stroke, only the signs last only a few minutes.
About 10 percent of strokes are preceded by TIAs. However, of those who have had one TIA or more, about 36 percent will later have a stroke. A person who has had one or more TIAs is 9.5 times more likely to have a stroke than someone of the same age and sex who has not.
Chain of Survival[Index]
Every stroke or TIA must be treated as a life-threatening emergency. Time is very important. A stroke in progress must be diagnosed. If you are going to receive tPA, a "clot-busting" drug treatment, or other appropriate therapy, you must get to a hospital quickly so a doctor can diagnose your stroke and treat you within 3 hours of the time symptoms begin. In the hospital emergency room, tests will determine if a TIA, stroke or another medical problem caused your symptoms.
Treatment for stroke will be different if an artery is blocked (ischemic stroke) or a blood vessel has ruptured (hemorrhagic stroke). To increase your chances of surviving a stroke, take these 5 steps in the Stroke Chain of Survival within three hours of the onset of symptoms:
Rapid recognition of stroke signs and symptoms: Recognize the symptoms and note when they first occur.
Rapid activation of the Emergency Medical Services (EMS) system: Call 9-1-1 immediately. Tell the operator that you have stroke warning signs.
Rapid transport and hospital pre-notification: Get to the hospital quickly via EMS; they will notify the emergency room.
Rapid start of pre-hospital care during EMS transport: Receive early assessments and care on the way to the hospital.
Rapid diagnosis and treatment at the receiving hospital: Receive prompt evaluation of the medical data and treatment to restore blood flow to the brain -- or other treatments as appropriate at the ER.
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Material taken from the American Heart Association.