Download Understanding Stroke Risk and Treatment

Understanding Stroke Risk and Treatment
Dr. Andre G. Douen, MD, PHD, FRCPC, FAHA
Stroke Neurologist,
Director, West GTA Stroke Program,
Chief division of Neurology, Trillium Health Partners,
Mississauga, ON Canada
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ISCHEMIC STROKE
What is a Stroke ?
Sudden loss of brain function due to reduced or complete
blockage of blood flow in any part of the brain.
Ischemic or non-bleeding stroke: Accounts for 85% of all
stroke and occurs when a blood clot blocks a blood vessel in
the brain.
Hemorrhagic or bleeding stroke: Accounts for 15% of all
stroke and occurs when a blood vessel breaks within or around
the brain. Example: Aneurysm rupture.
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What are the symptoms of stroke ?
•
Symptoms come on abruptly and depend on the area of the brain
affected and the extent of brain damage.
•
Sudden weakness or numbness especially on one side of the
body (facial weakness, drooling, limb weakness, unsteady walking).
•
Trouble speaking or understanding.
•
Loss of vision in one or both eyes.
•
Dizziness in association with other symptoms e.g. weakness,
numbness, speech or swallowing difficulty. Dizziness or vertigo
without other neurological symptoms, particularly if made worse by
head movements, suggests inner ear dysfunction rather than stroke.
•
Sudden explosive headache that come on within seconds might
suggest an aneurysm rupture. Gradual onset severe headache that
comes on over minutes are often due to migraine or other types of
headache. However, seek medical attention if concerned.
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Who are at risk of stroke?
Non-modifiable risk factors:
– Age: Risk of stroke increases with age.
– Gender: Men may have a higher lifetime risk of stroke, but women
have worse outcome from strokes.
– Family history: Often refers to “premature” vascular disease. If
parents or siblings sustain a stroke before the age 55yrs, then the risk
of stroke is higher as compared to individuals who do not have stroke
in first degree relatives.
– Ethnicity: First Nations people and those of African or South Asian
descent are more likely to have high blood pressure and diabetes, and
are at increased risk of heart disease and stroke. Hemorrhagic stroke
is also more prevalent in some Asian (Oriental) populations.
– Prior stroke or TIA (transient ischemic attack): Previous stroke or a
transient ischemic attack (often called “mini-strokes”), increases the
risk of recurrent stroke.
– Prior heart attack: Is associated with increase risk of stroke
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Who are at risk of stroke?
Modifiable risk factors:
– High blood pressure (hypertension)
– Atrial fibrillation (irregular heart beat)
– Smoking
– Diabetes
– High cholesterol
– Overweight
– Excessive alcohol consumption
– Physical inactivity (sedentary lifestyle)
– Illicit drug use
– Stress
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How do stroke risk factors actually lead to a stroke?
ATHEROSCLEROSIS: Plaques within blood vessels of the neck (or brain)
can lead to clot formation which blocks blood flow and cause stroke.
Carotid vessel
blocked
byvessel
a clot
Carotid
Blocked by a clot
CT Scan of Brain showing a
large ISCHEMIC stroke
Atherosclerosis: Blood clots formed at the site of a plaque can
“EMBOLIZE”, i.e. flow upwards and block blood vessels within the brain.
Carotid vessel
Blocked by a clot
Atherosclerosis: Also leads to weakening of the blood vessels within the
brain which can rupture and cause hemorrhagic stroke
Carotid vessel
Blocked by a clot
CT Scan of Brain showing a
large hemorrhage (bleed)
How do stroke risk factors actually lead to a stroke?
ATRIAL FRIBRILLATION
Atrial fibrillation (AF) is an irregular beating
of the atria (the 2 top chambers of the
heart). AF can lead to clot formation. The
clot (or thrombus) then drift into the
ventricles (the 2 lower chambers of the
heart) and are pumped out of the heart into
the brain, where blockage of a blood vessel
leads to stroke. The travelling clot is call an
embolus.
AF is associated with aging, high blood
pressure, heart disease, excess alcohol, and
overactive thyroid gland.
Embolization and Ischemic Stroke
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Is stroke common in young people?
• Stroke can occur in anyone – babies, children, teenagers,
young and middle aged adults as well as the elderly.
• While stroke occurs more commonly in the elderly it is not
uncommon in young individuals.
• In infants the causes are unknown in about 30% of cases,
while other causes include abnormal arteries (the blood
vessels that bring blood to the brain) or clotting of the veins
that surround the brain.
• In teenagers and young adults a sudden tear of an artery,
called a dissection, blood clotting disorders, and use of illicit
drug use are important considerations.
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What should done if someone might be having a stroke
• An acute stroke is an emergency situation where time
plays a crucial role in deciding which treatment should be
given.
• Be familiar with and recognize the symptoms of stroke.
• Call 911 immediately.
• Where available patients may be transported to a stroke
centre where specially trained stroke teams may be
available to assist with managing acute stroke.
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What can be done to treat an acute ischemic
(non-bleeding) stroke
• The clot busting drug “tissue plasminogen activator (tPA)”
has been shown to beneficial in dissolving the clots blocking
the blood vessels within the brain.
• tPA has to be given within 4.5hrs from the start of the
symptoms.
• There is ~ 6% risk of causing a bleed in the brain with tPA,
but studies show that at three months there is no difference
in the amount who die after receiving tPA compared to
those who do not get tPA.
• The main difference though is that more people recover with
tPA use.
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What can be done to treat an acute hemorrhagic
(bleeding) stroke
• Hemorrhages carry a higher risk of disability and death
compared to non-bleeding stroke.
• tPA cannot be used for this condition.
• If the bleeding is found to be due to an aneurysm, in many
cases the aneurysm can be closed off to stop recurrent
bleeding.
• Some patients have bleeding around the brain that may be
amenable to surgical removal of the clot.
• However, for bleeding within the brain tissue itself, i.e. not
due to aneurysms, there is no specific treatment. Attention
is placed on controlling blood pressure and general medical
care.
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How are stroke patients investigated and managed after
the acute event ?
• Patients are usually admitted to a hospital for further
investigations to determine what might have caused the stroke.
• Investigations might include: CT or MRI scan of the brain, an
ultrasound of the carotid blood vessels in the neck, and an ECG
or heart monitor to assess for irregular heart beat (atrial
fibrillation). A cardiac ECHO (ultrasound) might be helpful in
select cases.
• Studies show that management of patients on stroke units may
help to reduce stroke recurrence and improve outcome.
• Rehabilitation may help with recovery, however, sometimes the
stroke is so large and the disability so severe that rehabilitation
is futile.
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How can recurrence of ischemic (non-bleeding) stroke
be prevented ?
• For patients with non bleeding stroke in whom narrowing of
the carotid blood vessels in the neck is thought to be the
cause of the stroke, these vessels can be operated on to
open them up. This has been shown to reduce recurrent
stroke.
• If atrial fibrillation is thought to be the cause of the stroke,
patients are treated with anti-coagulant (blood thinning)
drugs to reduce clots being formed in the heart.
• If a cause is not found after investigations then patients are
usually treated with antiplatelet drugs (e.g. aspirin).
• All risk factors need to be addressed – control and treat
blood pressure, diabetes and cholesterol. Stop smoking and
lose weight.
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How can recurrence of hemorrhagic (bleeding) stroke
be prevented ?
• For patients with aneurysm rupture these can be closed off
with endovascular therapy (a small tube called a catheter is
placed into the artery and extended through into the brain to
the aneurysm. Small coils can then be placed within the
aneurysm to seal it off.
• Aspirin and other “blood thinning” drugs are not usually
used after a bleed in the brain unless there is some other
special medical reason to do so.
• All risk factors need to be addressed, i.e. lifestyle
modification, especially blood pressure control.
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How can the risk of stroke be lowered?
Be proactive:
– Know (record) and control your blood pressure if elevated
(lose weight, decrease salt in take, be compliant with
prescribed medications)
– Atrial fibrillation: Comply with “blood thinning” medication if
prescribed
– Lower cholesterol (diet, exercise, medication)
– Control diabetes
– Modify lifestyle
 Stop smoking
 Lose weight
 Reduce alcohol consumption
 Avoid illicit drug use
 Exercise
 Control stress
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