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neurology channel |
What is a stroke, brain attack?
A stroke or "brain attack" occurs when a blood clot blocks a blood
vessel
or artery, or when a blood vessel breaks, interrupting blood flow to an
area
of the brain.
When a stroke occurs, it kills brain cells in the immediate area.
Doctors call this area of dead cells an infarct. These cells usually
die within minutes
to a few hours
after the stroke starts.
When brain cells in the infarct die, they release chemicals that set
off
a chain reaction called the "ischemic cascade." This chain reaction
endangers
brain cells in a
larger, surrounding area of brain tissue for which the blood supply is
compromised
but not completely cut off. Without prompt medical treatment this
larger
area of
brain cells, called the penumbra, will also die. Given the rapid pace
of
the ischemic cascade, the "window of opportunity" for interventional
treatment
is about six
hours. Beyond this window, reestablishment of blood flow and
administration of neuroprotective agents may fail to help and can
potentially cause further damage.
When brain cells die, control of abilities which that area of the
brain once controlled are lost. This includes functions such as speech,
movement, and memory. The
specific abilities lost or affected depend on where in the brain the
stroke
occurs and on the size of the stroke (i.e., the extent of brain cell
death).
For example,
someone who has a small stroke may experience only minor effects such
as
weakness of an arm or leg. On the other hand, someone who has a larger
stroke
may be
left paralyzed on one side or lose his/her ability to express and
process language. Some people recover completely from less serious
strokes, while other individuals
lose their lives to very severe strokes.
Brain attack!
• Stroke is a "Brain Attack"
• Stroke happens in the brain rather than the heart.
• Stroke is an emergency!
• "Time is brain"
Why use the term brain attack?
The origination of the term "brain attack" and its application to
stroke are credited to Vladimir C. Hachinski, M.D., and John Norris,
M.D., both world-renowned
neurologists from Canada. NSA began to champion the term in 1990
because it
characterizes the medical condition and communicates the actual event
more
clearly
to the public than does the word "stroke." The brain is the most
delicate organ in the body. "To give the best chance of limiting
damage, brain attacks should be
heeded even more urgently than heart attacks," said Dr. Hachinski.
The symptoms of stroke should have the same alarming significance in identifying a brain attack that acute chest pain has in identifying a heart attack.
The public misperception that nothing can be done about stroke has
prevailed for too long. With the use of the term "brain attack," we
give stroke a definitive
name
and a unique face for the first time. Of all the images we use to
identify stroke, "brain attack" is the most descriptive, realistic and
powerful call
to action. The
appropriate response to a brain attack is emergency action, both by the
person
it strikes and the medical community.
Brain attack means medical emergency
Educating the public to treat stroke as a brain attack and to seek
emergency treatment is crucial because every minute lost, from the
onset of symptoms to the time of
emergency contact, cuts into the limited window of opportunity for
intervention.
The majority of patients don't report to the emergency room until more
than
24
hours after the onset of stroke symptoms. The longer the delay in
patient presentation, the more damage a stroke can do and the less
recovery can be
achieved.
One of the largest obstacles to emergency treatment is that many
people don't even know it when they are having a stroke. The University
of Cincinnati reported that
52 percent of their acute stroke patients were unaware they were
experiencing a stroke. Another factor in time of presentation is where
people are when they have
strokes. Those who have a brain attack in a public place where others
may
recognize the symptoms or see that something is wrong tend to report to
the
emergency
room sooner. That is why it is critical for everyone to "Be Stroke
Smart"
and learn the 3 Rs of stroke: Reduce risk, Recognize symptoms, Respond
by
calling 911.
Changing the Perception of Stroke
Myth
Reality
* Stroke is unpreventable
* Stroke is largely preventable
* Stroke cannot be treated
* Stroke requires emergency
treatment
* Stroke only strikes the elderly
* Stroke can happen to
anyone
* Stroke happens to the heart
* Stroke is a "Brain Attack"
* Stroke recovery only happens for a
few months following a stroke
* Stroke recovery continues
throughout life
Time to presentation
• 58% of stroke patients don't present until 24 hours or more after the onset
--Alberts et al, 1990
• 13 hours is median time from stroke onset to presentation
--Feldman et al, 1993
• 17% of adults over age 50 can't name a single stroke symptom
--NSA/Gallup Survey, 1996
Types of stroke
There are two main ways "brain attacks" can happen ischemic and
hemorrhagic strokes. In ischemic strokes, a blood clot blocks or
"plugs" a blood vessel in the
brain. In hemorrhagic strokes, a blood vessel in the brain breaks or
ruptures.
Ischemic stroke
In everyday life, blood clotting is beneficial. When you are
bleeding from
a wound, blood clots work to slow and eventually stop the bleeding. In
the
case of stroke,
however, blood clots are dangerous because they can block arteries and
cut
off blood flow, a process called ischemia. An ischemic stroke can occur
in
two ways
embolic and thrombotic strokes.
Embolic stroke
In an embolic stroke, a blood clot forms somewhere in the body
(usually the heart) and travels through the bloodstream to your brain.
Once in your brain, the clot
eventually travels to a blood vessel small enough to block its passage.
The
clot lodges there, blocking the blood vessel and causing a stroke. The
medical
word for
this type of blood clot is embolus.
Thrombotic stroke
In the second type of blood-clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. Strokes caused in this way are called thrombotic strokes. That's because the medical word for a clot that forms on a blood-vessel deposit is thrombus.
Blood-clot strokes can also happen as the result of unhealthy blood vessels clogged with a buildup of fatty deposits and cholesterol. Your body regards these buildups as multiple, tiny and repeated injuries to the blood vessel wall. So your body reacts to these injuries just as it would if you were bleeding from a wound it responds by forming clots.
Two types of thrombosis can cause stroke large vessel thrombosis and
small
vessel disease (or lacunar infarction).
Large vessel thrombosis
Thrombotic stroke occurs most often in the large arteries, so large
vessel
thrombosis is the most common and best understood type of thrombotic
stroke.
Most large
vessel thrombosis is caused by a combination of long-term
atherosclerosis followed by rapid blood clot formation. Thrombotic
stroke patients are also
likely to have
coronary artery disease, and heart attack is a frequent cause of death
in
patients who have suffered this type of brain attack.
Small vessel disease/Lacunar infarction
Small vessel disease, or lacunar infarction, occurs when blood flow is
blocked
to a very small arterial vessel. The term's origin is from the Latin
word
lacuna which
means hole, and describes the small cavity remaining after the products
of
deep infarct have been removed by other cells in the body. Little is
known
about the
causes of small vessel disease, but it is closely linked to
hypertension.
Hemorrhagic stroke
Strokes caused by the breakage or "blowout" of a blood vessel in the brain are called hemorrhagic strokes. The medical word for this type of breakage is hemorrhage. Hemorrhages can be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms. An aneurysm is a weak or thin spot on a blood vessel wall. These weak spots are usually present at birth. Aneurysms develop over a number of years and usually don't cause detectable problems until they break. There are two types of hemorrhagic stroke subarachnoid and intracerebral.
In an intracerebral hemorrhage, bleeding occurs from vessels within the brain itself. Hypertension is the primary cause of this type of hemorrhage.
In a subarachnoid hemorrhage (SAH), an aneurysm bursts in a large
artery on or near the thin, delicate membrane surrounding the brain.
Blood spills into the area
around the brain which is filled with a protective fluid, causing the
brain
to be surrounded by blood-contaminated fluid.
This happens in two main ways. In an ischemic stroke, a clot or
buildup of fatty tissue blocks or "plugs" a blood vessel in the brain.
The other type,
called a
hemorrhagic stroke, occurs when a blood vessel in the brain breaks or
ruptures.
Because about 85 percent of all brain attacks are ischemic, much of
stroke's
public health burden is attributed to this type. However, hemorrhagic
strokes
result in
significant cost, disability and death. Consider that while hemorrhagic
strokes
account for about one-fifth of all strokes, they are responsible for an
estimated
one-third of all stroke deaths.
Classification of hemorrhagic strokes
• Hemorrhagic strokes are divided into two types, named for the part of
the
brain where they occur. An intracerebral hemorrhage (ICH) is
characterized by bleeding
into the brain itself, while a subarachnoid hemorrhage (SAH) describes
bleeding
into the area that surrounds the brain. While these two types of
hemorrhagic
stroke
are similar, they generally arise from different causes and produce
different
outcomes.
• An understanding of hemorrhagic stroke offers hope for reducing
the death
and disability that results from the disease. Read on to learn more
about
how a
hemorrhagic stroke occurs, the risk factors you should be aware of, and
some
of the treatment methods doctors use.
Recognizing stroke symptom
Stroke is a brain attack, yet most people don't know the symptoms. In a
recent
NSA/Gallup poll, 17 percent of the respondents over age 50 couldn't
name
a single
stroke symptom. Stroke is an emergency! When someone experiences any of
these
symptoms, it is impossible to tell at first if it's a stroke or a
transient
ischemic
attack (TIA). If it is a stroke, immediate medical treatment can save
the
person's life and greatly enhance chances for successful rehabilitation
and
recovery. If it's a
TIA, the doctor will evaluate the underlying causes and begin
appropriate preventive measures. Even if these symptoms don't cause
pain or they go away
quickly,
call 911 immediately!!
The five most common stroke symptoms include:
• Sudden numbness or weakness of face, arm or leg, especially on one
side
of the body
• Sudden confusion, trouble speaking or understanding
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness, loss of balance or coordination
• Sudden severe headache with no known cause
Call 911 if you see or have any of these symptoms. Treatment can be more effective if given quickly. Every minute counts!
Other important but less common stroke symptoms include:
• Sudden nausea, fever and vomiting distinguished from a viral illness
by
the speed of onset (minutes or hours vs. several days)
• Brief loss of consciousness or period of decreased consciousness
(fainting,
confusion, convulsions or coma)
Recovery and rehab
Current statistics indicate that there are nearly 4 million people in
the
United States who have survived a stroke and are living with the
after-effects.
These numbers do not reflect the scope of the problem and do not count
the
millions of husbands, wives and children who live with and care for
stroke
survivors and who are, because of their own altered lifestyle, greatly
affected
by stroke.
The very word "stroke" indicates that no one is ever prepared for
this sudden, often catastrophic event. Stroke survivors and their
families can find workable
solutions to most difficult situations by approaching every problem
with
patience, ingenuity, perseverance and creativity.
Early recovery
There's still so much we don't know about how the brain compensates
for
the damage caused by stroke. Some brain cells may be only temporarily
damaged,
not
killed, and may resume functioning. In some cases, the brain can
reorganize its own functioning. Sometimes, a region of the brain "takes
over" for a
region damaged
by the stroke. Stroke survivors sometimes experience remarkable and
unanticipated
recoveries that can't be explained. General recovery guidelines show:
• 10 percent of stroke survivors recover almost completely
• 25 percent recover with minor impairments
• 40 percent experience moderate to severe impairments requiring
special care
• 10 percent require care in a nursing home or other long-term care
facility
• 15 percent die shortly after the stroke
Rehabilitation
Rehabilitation actually starts in the hospital as soon as possible
after
the stroke. In patients who are stable, rehabilitation may begin within
two
days after the stroke
has occurred, and should be continued as necessary after release from
the
hospital.
Depending on the severity of the stroke, rehabilitation options
include:
• A rehabilitation unit in the hospital
• A subacute care unit
• A rehabilitation hospital
• Home therapy
• Home with outpatient therapy
A long-term care facility that provides therapy and skilled nursing
care
The goal in rehabilitation is to improve function so that the stroke
survivor
can become as
independent as possible. This must be accomplished in a way that
preserves dignity and motivates the survivor to relearn basic skills
that the stroke may have taken
away - skills like eating, dressing and walking.
Stroke risk factor and their impact
Stroke is one of the most preventable of all life-threatening health
problems.
The two primary types of risk factors for stroke are those that are
controllable
and those
that are not. It's important to remember that having one or more
uncontrollable stroke risk factors DOES NOT MAKE A PERSON FATED TO HAVE
A STROKE.
With proper attention to controllable stroke risk factors, the impact
of
uncontrollable factors can be greatly reduced.
Uncontrollable Stroke Risk Factors Include:
• Age - The chances of having a stroke go up with age. Two-thirds of all strokes happen to people over age 65. Stroke risk doubles with each decade past age 55.
• Gender - Males have a slightly higher stroke risk than females.
But, because women in the United States live longer than men, more
stroke survivors over age 65
are women.
• Race - African-Americans have a higher stroke risk than most other racial groups.
• Family history of stroke or TIA - Risk is higher for people with a family history of stroke or TIA.
• Personal history of diabetes - People with diabetes have a higher
stroke
risk. This may be due to circulation problems that diabetes can cause.
In
addition, brain
damage may be more severe and extensive if blood sugar is high when a
stroke
happens. Treating diabetes may delay the onset of complications that
increase
stroke
risk. However, even if diabetics are on medication and have blood sugar
under
control, they may still have an increased stroke risk simply because
they
have diabetes.
Controllable stroke risk factors
Treatable Medical Disorders that Increase Stroke Risk Include:
• High blood pressure - Having high blood pressure, or hypertension,
increases
stroke risk four to six times. It is the single most important
controllable
stroke risk
factor. High blood pressure is often called "the silent killer" because
people
can have it and not realize it, since it often has no symptoms.
Hypertension
is a common
condition, affecting approximately 50 million Americans, or one-third
of
the adult population. Blood pressure is high if it is consistently more
than
140/90. Between 40 and 90 percent of all stroke patients had high blood
pressure
before their stroke. Hypertension puts stress on blood vessel walls and
can
lead to strokes from blood clots or hemorrhage.
• Heart Disease
Atrial fibrillation and other heart diseases - Heart disease such as
atrial
fibrillation increases stroke risk up to six times. About 15 percent of
all
people who have a
stroke have a heart disease called atrial fibrillation, or AF, which
affects
more than 1 million Americans. AF is caused when the atria (the two
upper
chambers of the
heart) beat rapidly and unpredictably, producing an irregular
heartbeat. AF
raises stroke risk because it allows blood to pool in the heart. When
blood
pools, it tends to form clots which can then be carried to the brain,
causing
a stroke.
Normally, all four chambers of the heart beat in the same rhythm
somewhere between 60 and 100 times every minute. In someone who has AF,
the left atrium
may
beat as many as 400 times a minute. If left untreated, AF can increase
stroke
risk four to six times. Long-term untreated AF can also weaken the
heart,
leading to
potential heart failure. The prevalence of AF increases with age. AF is
found
most often in people over age 65 and in people who have heart disease
or
thyroid
disorders. Among people age 50 to 59, AF is linked to 6.7 percent of
all
strokes. By ages 80-89, AF is responsible for 36.2 percent of all
strokes.
• Coronary Heart Disease and High Cholesterol - High cholesterol can
directly
and indirectly increase stroke risk by clogging blood vessels and
putting
people at
greater risk of coronary heart disease, another important stroke risk
factor.
A cholesterol level of more than 200 is considered "high." Cholesterol
is
a fatty substance
in the blood that our bodies make on their own, but we also get it from
fat
in the foods we eat. Certain foods (such as egg yolks, liver or foods
fried
in animal fat or
tropical oils) contain cholesterol. High levels of cholesterol in the
blood
stream can lead to the buildup of plaque on the inside of arteries,
which
can clog arteries and
cause heart or brain attack.
Personal history of stroke or TIA - People who have already had a
stroke or TIA are at risk for having another. After suffering a stroke,
men have a 42 percent
chance of recurrent stroke within five years, and women have a 24
percent chance of having another stroke. TIAs are also strong
predictors of stroke because 35
percent of those who experience TIAs have a stroke within five years.
Lifestyle factors that increase stroke risk include
• Smoking - Smoking doubles stroke risk. Smoking damages blood
vessel walls,
speeds up the clogging of arteries by deposits, raises blood pressure
and
makes the
heart work harder.
• Alcohol - Excessive consumption of alcohol is associated with
stroke in a small number of research studies. Its specific role in
stroke has not
yet been determined
or proven. Recent studies have also suggested that modest alcohol
consumption (one 4 oz. glass of wine or the alcohol equivalent) may
protect against stroke
by
raising levels of a naturally occurring "clot-buster" in the blood.
• Weight - Excess weight puts a strain on the entire
circulatory system. It also makes people more likely to have other
stroke risk factors such as high cholesterol,
high blood pressure and diabetes.
This information was developed by the National Stroke Association and is herewith used with permission.
National Stroke Association. All About Stroke; Stroke Information Library. Available at: http://www.stroke.org/. Accessed November 8, 1999.
The information in this document is for general educational
purposes only. It is not intended to substitute for personalized
professional advice. Although the
information was obtained from sources believed to be reliable, Arbor
Publishing
Corp, its representatives, and the providers of the information do not
guarantee
its
accuracy and disclaim responsibility for adverse consequences resulting
from
its use. For further information, consult a physician and the
organization referred to
herein.