CVA - Stroke
Overview, Causes, & Risk Factors
A stroke is the death of brain tissue that occurs when the brain does not get
enough blood and oxygen.
What is going on in the body?
Strokes are classified as ischemic strokes or hemorrhagic strokes.
Ischemic strokes happen when the blood supply to the brain is
interrupted. The brain cells then die from lack of oxygen.
Hemorrhagic strokes occur when blood vessels in the brain burst and
release blood into the area around the brain cells. The blood then damages the
brain cells. The products released when cells die cause swelling in the brain.
Since the skull doesn't allow much room for expansion, this swelling can damage
the brain tissue even further.
Examples of ischemic strokes are:
stroke from atherosclerosis,
occurs when the arteries supplying the brain are narrowed by plaque formation
on the vessel walls
stroke from carotid stenosis,
which is a blockage in one of the carotid arteries in the neck
arteritis, or artery inflammation, in an artery that supplies the brain.
This may be due to a condition called temporal arteritis, for example.
stroke from carotid dissection. A carotid dissection occurs when
one of the carotid arteries in the neck is torn by an injury and blood flow to
the brain is blocked.
polycythemia vera, a blood
that causes blood cells to multiply and the blood to thicken. The thickened
blood prevents normal oxygenation of brain cells.
stroke from cardiogenic
a condition in which blood clots travel from the heart. Blood clots from the
heart may be caused by an irregular heartbeat called atrial
fibrillation, severe congestive heart failure,
and heart attack.
stroke caused by cholesterol or plaque from an artery in the neck. When the
cholesterol or plaque travels and blocks an artery supplying the brain, a
severe migraine headaches, which cause constriction of the
blood vessels within the brain and deprive brain cells of oxygen
Hemorrhagic strokes occur when there is bleeding into the brain
caused by damage to the blood vessels. A hemorrhagic stroke may be caused by:
high blood pressure
abnormal bleeding from blood-thinning medications, such as warfarin or
hemophilia A or hemophilia B, which are blood disorders
prevent normal blood clotting
low numbers of platelets, a type of blood cell involved in blood
clotting. Low platelet counts are seen in a number of diseases and conditions,
including acute infections and a severe allergic reaction known as anaphylactic shock.
rupture of a cerebral aneurysm, or
weakened blood vessel wall within the brain
sickle cell disease, an inherited condition that results in
abnormal red blood cells
a group of abnormal blood vessels within the brain known as an
arteriovenous malformation, or AVM
eclampsia, a complication of
pregnancy that causes high blood pressure in the mother
Stroke is the third leading cause of death in the US and many other
countries, right after heart
What are the causes and risks of the condition?
Strokes are caused by an interruption of the blood flow to brain cells or by
damage to brain cells.
The American Heart Association has recently issued guidelines for stroke
prevention. The guidelines discuss risk factors for stroke in 3 categories:
nonmodifiable, well-documented modifiable, and less well-documented or
The nonmodifiable factors are ones that cannot be changed by the individual
increasing age. A person's risk of stroke doubles each year after age
race. Strokes occur approximately twice as often in blacks and Hispanics as
they do in whites.
gender. Men have a 50% higher chance of stroke than women do.
family history of stroke or transient
ischemic attack (TIA). A TIA is a short, reversible form of stroke that
may serve as an early warning sign of stroke.
Well-documented modifiable risk factors are those that can be changed by the
individual in conjunction with his or her healthcare provider. These factors
are linked to stroke by strong research findings, and there is documented proof
that changing the risk factor lowers a person's risk of stroke. These factors
high blood pressure
asymptomatic carotid stenosis, or
narrowing of one of the arteries in the neck
sickle cell anemia, a blood
disorder that forms abnormal red blood cells
high cholesterol levels in the
blood, including total cholesterol
LDL or "bad cholesterol." Low
of HDL or "good cholesterol" are
cause for concern.
atrial fibrillation, an abnormal
Less well-documented or potentially modifiable risk factors for stroke are
those that have less proof of either a link to stroke or the impact of
modifying the risk factor. These factors include:
high blood levels of homocysteine, a blood component sometimes associated
with a higher risk of stroke
blood disorders, such as blood that clots easily or deficiencies of various
hormone replacement therapy
The AHA currently states that the risk of stroke associated with HRT appears
low but needs further study.
use of birth control pills, or oral contraceptives
inflammatory processes, such as a chronic infection with chlamydia
Several recent studies have identified factors that seem to increase or
decrease the risk of stroke in particular groups of people. These studies,
which warrant further investigation, include these findings:
People who were treated for high blood
pressure with thiazide diuretics, such as hydrochlorothiazide, had a
significantly lower stroke risk than people on ACE inhibitors or calcium
Women ages 39 to 50 who ate more fish and omega-3 polyunsaturated fatty acids had a reduced risk of ischemic stroke. This was particularly true in women who did not take aspirin regularly.
Women ages 15 to 44 who had 2 drinks of wine a day had a 40% to 60% lower
risk of stroke than women who did not drink
Phenylpropanolamine, a compound contained in appetite suppressants and cold
remedies, significantly increased the risk of hemorrhagic stroke in women 18 to 49
years of age. The Food and Drug Administration (FDA) has since asked
manufacturers to remove phenylpropanolamine from their products.
In one study, people who were treated in emergency departments for
transient ischemic attacks (TIA) had a 25% chance of having a stroke or other
serious health event within the next 90 days.
Symptoms & Signs
What are the signs and symptoms of the condition?
Strokes can cause many different signs and symptoms, depending on the area of
the brain that is damaged. Some people have multiple areas of damage. Most
strokes begin suddenly, develop rapidly, and cause brain damage within minutes.
Signs or symptoms may include:
problems with movement, such as weakness, clumsiness, or paralysis.
These are often on only one side of the body. In some cases, people may only
have weakness or clumsiness in their hand. In other cases, one entire half of
the body becomes paralyzed.
numbness or a lack of feeling, which is also often on only one side
of the body
speech impairments, including
slurred speech or difficulty finding the correct word
difficulty doing math or writing
difficulty understanding speech or writing
inability to recognize family members or common objects
dementia, a condition that affects memory, understanding, and the
ability to carry out the normal activities of daily life
blurred vision or total vision loss
balance problems, known as ataxia
the inability to breathe on one's own. This may require a person to be put
on an artificial breathing machine, or
Diagnosis & Tests
How is the condition diagnosed?
The first step in diagnosis of stroke is a medical history and physical exam. This may
be all that is needed to make the diagnosis. In other cases, further tests may
Cranial MRIs and cranial CT
scans may be ordered to show the type, size, and location of the
stroke. They can also show whether or not there is bleeding in the brain, which
can help with some treatment decisions.
Other tests may be ordered to help determine the cause of the stroke. For
instance, a special X-ray test of the neck arteries can detect blockage.
Certain X-ray tests of the heart can show heart failure or changes from a heart
attack. A heart tracing, or ECG, can show abnormal heartbeats, such as atrial
fibrillation, or certain changes from a heart attack.
Prevention & Expectations
What can be done to prevent the condition?
The American Heart Association guidelines for stroke prevention address both
modifiable and less well-documented or potentially modifiable risk factors.
Measures to reduce the modifiable risk of
high blood pressure, a major cause of stroke, include:
measurement of blood pressure
adults at least every 2 years to screen for
high blood pressure
moderation in alcohol
moderate sodium intake
for those who smoke, quitting
medications to treat high blood pressure if the person's blood pressure is
over 140/90 after 3 months of these lifestyle modifications, or if the initial
blood pressure is over 180/100
Other measures to reduce an individual's modifiable risk factors for stroke may
smoking cessation using
patches, counseling, and formal smoking programs
control of blood sugar levels in a person with diabetes through medication, diet, and exercise
the use of ramipril in people with diabetes. A recent study showed that people with diabetes have a 33% lower risk of ischemic stroke if they take ramipril.
careful evaluation of asymptomatic carotid stenosis to determine the need for surgery. Coronary artery surgery, such as an endarterectomy, may be
indicated. An endarterectomy opens the narrow portion of the artery and
increases the blood flow to the brain. People with carotid stenosis should
also work closely with their healthcare providers to control other risk factors
semiannual screening of children with
sickle cell anemia, using ultrasound to determine the child's risk of
treatment of atrial fibrillation
with blood thinners such as aspirin or warfarin, depending on the person's age
and other risk factors
monitoring of high levels of total cholesterol or LDL, as well as low
levels of HDL. Depending on the blood levels and the person's other risk
factors, medications to lower cholesterol may be given.
Measures to reduce less well-documented or potentially modifiable risks for
stroke may include:
weight reduction in overweight persons
30 or more minutes of moderate exercise a day for most individuals.
People with heart disease or
disabilities should be in a medically supervised exercise program.
a healthy diet for preventing heart
containing at least 5 fruits and vegetables a day
for those who drink alcohol,
drinking in moderation. The AHA defines moderate drinking as no more than 2
drinks a day for men and 1 drink a day for women.
seeking treatment for drug
monitoring of blood levels of homocysteine. For most individuals, a
well-balanced diet following the food guide pyramid will provide enough folic
acid and B vitamins to maintain a healthy homocysteine level. For people with
elevated homocysteine levels, supplements containing folic acid and B vitamins
may be recommended.
avoiding the use of oral contraceptives in women with other stroke risk
Some people have early warning signs that they are at risk for strokes. The
most common warning sign is what is known as a transient ischemic
attack, or TIA. This is a type of reversible stroke that often goes
away after a few minutes. These people can often get treatment that will
prevent a stroke in the future. For instance, they may be advised to take
aspirin or have carotid artery surgery to correct a blockage in a
What are the long-term effects of the condition?
Strokes can cause death or permanent disability. Though many people recover
some function in the first several months after a stroke, others show no
improvement. Some people have several small strokes over time and slowly get
worse with each one.
What are the risks to others?
Strokes are not contagious and pose no risk to others.
Treatment & Monitoring
What are the treatments for the condition?
Most people with strokes are treated right away with only aspirin if they do
not have bleeding into the brain. This only serves to help prevent further
strokes. In cases when a stroke is caught in the first few hours, a
clot-busting medication may be used to reverse a stroke. This is why early
recognition of a stroke can be important.
If someone has the early warning signs of stroke, the emergency medical system should be contacted
These signs include a sudden onset of:
weakness or numbness of the
arm, or leg, especially on one side of the body
trouble walking or loss of balance, known as ataxia
speech impairments, including
trouble speaking or understanding speech
Specific types of medication may be needed in special cases. For instance,
those with a heart infection may be given antibiotics. Those with arteritis are often given corticosteroids, such as prednisone, to reduce inflammation in the
If an individual has significant narrowing of the carotid arteries, a carotid
endarterectomy may be recommended to widen them. This surgical procedure removes
the cholesterol plaques and may prevent future strokes. The decision to
perform surgery will depend on the person's neurological status, the type of
plaque clogging the artery, and whether the plaque has a break in it, known as
Supportive therapy may also be needed with some strokes. This may include an artificial breathing machine, or
ventilator, and an artificial
feeding tube if the person cannot swallow.
Rehabilitation services can help to improve a person's function after a stroke.
Physical therapy and other therapy, such as speech
therapy or occupational therapy, may be used to maximize
What are the side effects of the treatments?
Side effects depend on the treatments used. For instance, aspirin may cause
allergic reactions, stomach upset, or bleeding. Clot-busting
medications can cause excessive bleeding. A
ventilator may sometimes cause damage to the lungs or an infection.
A carotid artery endarterectomy can cause bleeding, infections, and allergic reactions to the anesthesia. On rare occasions, carotid
endarterectomy can cause a stroke or heart attack to occur.
What happens after treatment for the condition?
After the person is stable, treatment of the risk factors for stroke, as well
as the cause of the stroke, is important to prevent further strokes. For
instance, stopping smoking and controlling high blood pressure, diabetes, and high cholesterol
are advised for most people.
Those with arteritis are often maintained on medications to reduce inflammation
for long periods. Those with clots in the heart are often put on medications to
thin the blood, such as warfarin.
Many people need assistance of one form or another after a stroke. This may
range from using a walking cane to needing 24-hour-a-day skilled nursing
care. Ongoing therapy to improve function is usually advised for at least 6
months if the person is able.
How is the condition monitored?
People having a stroke are often admitted to the hospital for close monitoring.
Once the person is stable, he or she can often be sent home or to a skilled
nursing facility or rehabilitation center for further therapy.
Other monitoring is related to the cause. For instance, those with clots in
their heart need repeat blood tests, such as a PT test, to monitor the effects of
medications used to thin the blood. Any new or worsening symptoms should be
reported to the healthcare provider.
Author:Adam Brochert, MD
Editor:Ballenberg, Sally, BS
Reviewer:Eileen McLaughlin, RN, BSN
Harrison's Principles of Internal Medicine, 1998, Fauci et al.