Stroke >
What is stroke?
Stroke is the third leading cause of death and the No. 1 cause of adult disability.
Stroke is a type of cardiovascular disease. It affects the arteries leading to and within the brain. A stroke or "brain attack" occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. When that happens, part of the brain cannot get the blood (and oxygen) it needs, so it starts to die.
When brain cells die during a stroke, abilities controlled by that area of the brain are lost. These abilities include speech, movement and memory. How a stroke patient is affected depends on where the stroke occurs in the brain and how much the brain is damaged.
For example, someone who has a small stroke may experience only minor problems such as weakness of an arm or leg. People who have larger strokes may be paralyzed on one side or lose their ability to speak. Some people recover completely from strokes, but more than 2/3 of survivors will have some type of disability.
What are the types of stroke?
Stroke can be caused either by a clot obstructing the flow of blood to the brain or by a blood vessel rupturing and preventing blood flow to the brain.
There are two types of stroke, hemorrhagic and ischemic. Ischemic strokes can be further broken down into two types – embolic and thrombotic.
- Of all strokes, 87% are ischemic.
- Embolic strokes are caused by a traveling atherosclerotic clot.
- Atherosclerosis is a condition in which fatty material is deposited along the walls of arteries. This fatty material thickens, hardens and may eventually block the arteries.
- Thrombotic strokes are caused by blockages in the arteries providing blood flow to the brain.
Stroke Risks?
High blood pressure is the number one reason that you might have a stroke. Having a blood pressure reading less than 120/80 mm Hg halves your risk of stroke.
The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.
Certain medications increase the chances of clot formation, and therefore your chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.
In persons ages 45-64 years old, 8-12% of ischemic strokes result in death in 30 days.
The relative risk of stroke in heavy smokers is twice that of light smokers. Stroke risk decreases significantly 2 years after cessation of cigarette smoking and is at the level of nonsmokers by 5 years.
Atrial fibrillation is an independent risk factor for stroke, increasing the risk about five-fold.
In adults over 55 years of age, the lifetime risk for stroke is greater than 1 in 6.
Stroke risk factors that cannot be changed include being over age 55, family history of stroke, being of African-American race and male gender.
Factors that can be modified include high blood pressure, high cholesterol, smoking, diabetes, artery disease and atrial fibrillation (a heart rhythm disorder).
Diagnosis of Stroke
When someone has shown symptoms of a stroke or a TIA (transient ischemic attack), a doctor will gather information and make a diagnosis. A doctor may use many different tests. The ones listed here are just some of the more common options:
- Imaging tests give a picture of the brain similar to X-rays i.e. CT scan.
- Electrical tests record the electrical impulses of the brain i.e. EEG.
- Blood flow tests show any problem that may cause changes in blood flow to the brain.
Acute and Preventative Treatments of Stroke
Because their mechanisms are different, the treatments for the types of stroke are different.
Carotid endarterectomies have been found to be highly beneficial for persons who are symptom free but have a severe stenosis of 60-99%. In this group, the surgery reduces the estimated 5-year risk of stroke by more than half, from about 1 in 10 to less than 1 in 20.
Surgery, medications, hospital care and rehabilitation are all accepted stroke treatments.
When the carotid artery in the neck is partially blocked by a fatty buildup, called plaque, surgery called carotid endarterectomy might be used to remove the accumulated plaque.
Cerebral angioplasty is another technique in which balloons, stents and coils are used to treat some types of problems with the brain's blood vessels. Its widespread use depends on its safety and effectiveness.
What are the effects of Stroke?
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.
The length of time to recover from a stroke depends on its severity. From 50-70% of stroke survivors regain functional independence but 15-30% are permanently disabled and 20% require institutional care at 3 months after onset.
Effects of a left-sided stroke include paralysis, speech/language problems, a slow, cautious behavioral style and memory loss.
The effects of stroke on the right hand side of the body will include paralysis, vision problems, a quick, inquisitive behavioral style and memory loss.
Worldwide Stroke Statistics
- Stroke is the third most common cause of death worldwide after ischemic heart disease and all types of cancer combined.
- Two-thirds of stroke deaths occur in less developed countries.
- Stroke caused 3% of the world’s disability burden in 1990.
- By 2020, stroke mortality will have almost doubled mainly as a result of an increase in the proportion of older people and the future effects of current smoking patterns in less developed countries.
- In the early 1990s, stroke mortality was lowest, and had been declining steeply, in Western Europe, the USA, Australia and Japan, and was almost three times higher in South America.
- According to the World Health Organization, 15 million people suffer stroke worldwide each year. Of these, 5 million die and another 5 million are permanently disabled.
- Europe averages approximately 650,000 stroke deaths each year.
- In developed countries, the incidence of stroke is declining - largely due to efforts to lower blood pressure and reduce smoking. However, the overall rate of stroke remains high due to the aging of the population.
Sources: World Health Report - 2007, from the World Health Organization; International Cardiovascular Disease Statistics (2007 Update), a publication from the American Heart Association.