What is a stroke?
A stroke is damage to the brain due either to blockage in
blood flow or to loss of blood from blood vessels in the brain. Blockage in
blood flow or loss of blood causes the brain to lack oxygen and blood
nutrients.
The brain requires a constant flow of blood to work
properly. If the blood flow is disrupted, brain cells do not receive enough
oxygen, resulting in cell death. The degree of damage that results from a
stroke is dependent on where and how much blood flow to the brain is
interrupted.
A stroke is also called a cerebrovascular accident,
cerebrovascular disease or CVA.
Categories of strokes
There are two
major categories of stroke: hemorrhagic and ischemic. Within the major
categories are different kinds of strokes.
In ischemic strokes, there is a blockage of blood flow to
the brain. About 80 percent of all strokes are ischemic.
Ischemic strokes usually occur when a blood clot forms in a
blood vessel in the brain or neck. Blood clots can also travel from other parts
of the body, such as the heart, to the neck or brain and cause a stroke. A
blood vessel that is extremely narrowed can also cause an ischemic stroke.
In hemorrhagic strokes a blood vessel in the brain is
leaking or broken. These types of strokes account for approximately one out of
five strokes. Hemorrhagic stroke is associated with a higher death rate than
ischemic stroke. Hemorrhage can occur from a weak or thinned out area on the
artery wall that balloons out over time, and then ruptures.
Kinds of strokes
A stroke may also develop paralysis in one or both sides of
the body.
How does a stroke
occur?
A stroke occurs when a blood vessel bringing oxygen and
nutrients to the brain bursts or becomes blocked. Vessels can be blocked by
blood clots or other particles. When blockage occurs, nerve cells in the part
of the brain that is deprived of oxygen become dysfunctional, the part of the
body that is controlled by these cells is also unable to perform.
What causes a stroke?
Several different mechanisms may result in stroke: thrombus
formation, embolus, and hemorrhage.
Thrombosis formation is an obstruction within an artery resulting
from the gradual accumulation of plaque (atherosclerosis). If large enough, the
obstructions may restrict or completely block blood flow through the artery.
Blockage of arteries supplying the brain causes stroke if alternative routes
are not available to deliver an adequate blood supply.
Embolus is an obstruction of an artery due to material
formed elsewhere in the body (such as the heart). The materials are usually
generated in one part of the body and travel throughout the body until they
become trapped in a blood vessel. The blood vessel then is unable to supply the
brain with blood and nutrients.
Hemorrhage results from a rupture of a blood vessel located
in the brain. Blood erupts at high pressure in the brain or in tissue
surrounding the brain. Normal brain cells may be destroyed. The presence of
blood often results in severe headache, lethargy or coma.
Multiple factors: Most
strokes are associated with atherosclerosis, high blood pressure, oxygen damage
or a combination of the three.
Medication: some medications
may increase the risk of developing a stroke. Vioxx, a medication used to treat
arthritis was pulled off the market in September 2004 because is linked to
strokes and heart attacks.
What does a stroke
affect?
Stroke affects different people in different ways, depending
on the type of stroke, the area of the brain affected and the extent of the
brain injury. Brain injury from a stroke can affect the senses, motor activity,
speech and the ability to understand speech, behavioural patterns, though
patterns, memory and emotions. Paralysis or weakness on one side of the body is
common.
A stroke survivor may cry easily or experience sudden mood
swings, often for no apparent reason. This is called emotional liability.
Laughing uncontrollably also may occur but isn’t as much common as crying. Depression
is common, as stroke survivors may feel less than “whole”.
A stroke can also affect seeing, touching, moving and
thinking, so a person’s perception of everyday objects may be changed. Stroke
survivors may not be able to recognize and understand familiar objects the way
they did before. When vision is affected, objects may look closer or farther
away than they really are, causing survivors to have spills at the table or collisions
when walking.
Strokes may cause people to have problems understanding
speech. They also may have trouble saying what they are thinking. This is
called aphasia. Aphasia affects the ability to talk, listen, read and write.
Aphasia is most common when a stroke weakens the body’s right side.
A related problem is that a stroke can affect muscles used
in talking (those in the tongue, palate and lips). Speech can be slowed,
slurred or distorted, so stroke survivors can be hard to understand. This is
called dysarthria and may require the help of a speech expert.
After a stroke, the individual often has difficulty thinking
clearly. Planning and carrying out even simple activities may be hard. Stroke
survivors may not know how to start a task, confuse the sequence of logical
steps in tasks, or forget how to do tasks they’ve done many times before.
Signs of a major
stroke
Some of the signs of major stroke are facial weakness,
inability to talk, loss of bladder control, difficulty in breathing and
swallowing, and paralysis or weakness, particularly on one side of the body.
Risks of developing a
stroke?
Some of the most common risks of developing a stroke are: a
history of high blood pressure, heart diseases, smoking, atherosclerosis,
diabetes, migraine headaches, high levels of tryglycerides (a fatty substance
in the blood), use of birth control pills, stroke statistics, news and
interesting information.
Can a stroke be
treated?
Anyone who has a stroke needs immediate hospitalization,
possibly including intensive care and life support. Unfortunately, there is no
known cure for a stroke.
Women and strokes
Women who snore regularly may increase their risk of heart
attack or stroke by 33 percent notes a researcher from the Harvard School of
Public Health of Cambridge, Massachusetts. A temporary shortage of oxygen during snoring
can activate the sympathetic nervous system, like heart rate and breathing,
possibly leading to high blood pressure.
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