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A stroke is a disruption of blood flow to a part of
the brain, causing it to stop working properly and damaging brain cells.
A stroke is a medical emergency that requires immediate treatment.
Symptoms usually occur suddenly but will vary depending on the part of
the brain that is affected.
Approximately 8000 New Zealanders have a stroke each year – it is the
third biggest killer and the greatest cause of disability in New
Zealand. Recurrent stroke is frequent; about 25 per cent of people who
recover from their first stroke will have another stroke within five
years. The best means to prevent a stroke are to manage related medical
conditions (notably high blood pressure) and lifestyle factors.
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Types of strokes
Ischaemic Strokes:
Ischaemic strokes occur when a blood clot completely blocks an artery in
or to the brain. They are the most common type of stroke, occurring in
85 – 90% of cases. Ischaemic strokes can be either thrombotic or
embolic.
Thrombotic strokes occur when a blood clot (thrombus) blocks an artery
that has been narrowed by the build-up of fatty deposits (plaques)
during a process known as atherosclerosis.
Embolic strokes are due to a clot that has formed outside the brain and
travels to the brain in the blood stream. When this occurs the clot is
known as an embolus (plural = emboli).
Haemorrhagic Strokes:
Haemorrhagic strokes occur when an artery within the brain ruptures
(bursts) and leaks blood into the brain. The presence of this extra
blood causes pressure to build within the area of the brain where the
bleed has occurred. This causes damage to the brain tissue in that area
with resulting loss of function.
Haemorrhagic strokes are less common than ischaemic strokes but their
effects are generally more severe. Haemorrhagic strokes can be either
subarachnoid or intracerebral.
Subarachnoid haemorrhage (SAH) - when blood leaks onto the surface of
the brain.
Intracerebral haemorrhage (ICH) - when there is bleeding into the brain
tissue itself.
Rupture of an artery can be due to factors such as an aneurysm (where a
weakened section of an artery balloons out), an arteriovenous
malformation (AVM) (a congenitally abnormal connection of blood
vessels), or extremely high blood pressure.
Mini stroke (transient ischaemic attack):
Transient ischaemic attacks (TIA) occur when there is a temporary
disruption in the blood flow to the brain. This can be due to a
narrowing in an artery in or to the brain, or as a result of a blood
clot that quickly dislodges itself allowing blood to flow again.
Symptoms of a TIA can be similar to those of a stroke and can include
sudden weakness and/or numbness of face, arm and/or leg, sudden blurred
or loss of vision in one or both eyes, sudden difficulty speaking or
understanding what others are saying, sudden dizziness, loss of balance
or difficulty controlling movements. Symptoms may last for only a few
minutes or up to a few hours and resolve within 24 hours. If symptoms
last longer than 24 hours the condition is diagnosed as a stroke.
Suffering a TIA increases the risk of having a full-blown stroke and
having a TIA should be seen as a clear warning that a more severe stroke
might follow. Thirty percent of stroke patients have previously had a
TIA. Immediate medical attention should be sought if a TIA is suspected
as they can be a warning sign that a more severe stroke might follow.
The Stroke Foundation recommends a person with a suspected TIA should go
directly to hospital for medical assessment.
Stroke risk
People of all ages and genders can suffer a stroke. In New Zealand
approximately 22 people have a stroke each day.
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Risk factors multiply and the greater the number, the greater the chance
of a stroke. High blood pressure (hypertension) is the leading risk
factor for stroke.
Seventy-five percent of strokes occur in people over 65 years of age.
Ischaemic strokes make up the majority of strokes in older people while
younger people are more likely to suffer a haemorrhagic stroke.
Approximately 75% of subarachnoid haemorrhages occur in people under 65
years of age.
Ethnicity is a factor and Maori and Pacific Island New Zealanders are
more likely to suffer a stroke than European New Zealanders. Men are
more likely to suffer a stroke than women. Pregnant women also have a
slightly increased risk of haemorrhagic stroke.
There are controllable and uncontrollable factors that increase the risk
of stroke. Uncontrollable risk factors (ie. risks you cannot reduce
through treatment or lifestyle changes) include:
Age
Male gender
Family history
Ethnicity
Previous TIA
Early detection and effective management of controllable stroke risk
factors can greatly reduce the possibility of stroke. Controllable risk
factors for TIA and stroke include:
High blood pressure
Heart disease
Heart rhythm disorders eg: atrial fibrillation
Smoking
Diabetes
High blood cholesterol levels
Oral contraceptives
Excessive alcohol intake
Obesity
Signs and symptoms
Signs and symptoms of a stroke usually occur suddenly. The type of
symptoms experienced will depend on what area of the brain is affected.
The areas of the brain that control function on one side of the body are
often located in the opposite side of the brain. Therefore, lack of
blood to one side of the brain can often result in signs and symptoms on
the opposite side of the body. Common initial symptoms of a stroke
include:
Severe headache
Impairment or loss of vision
Memory loss
Confusion
Loss of balance or co-ordination
Poor balance and dizziness
Sudden numbness, paralysis or weakness of an arm, leg or side of the
face.
Slurred or abnormal speech
Loss of consciousness
Incontinence
A stroke can cause permanent loss of function. The type and degree of
this loss of function is determined by which area of the brain has been
affected and the speed and success of treatment given. Permanent effects
of a stroke can include:
Impaired vision
Difficulty understanding or forming speech
Severe weakness or paralysis of the affected side (hemiplegia)
Numbness, strange sensations or pain - sometimes made worse by movement
or temperature change
Swallowing difficulties
Depression
Emotional problems, such as difficulty controlling emotions or
expressing inappropriate emotions.
Stoke may also cause problems with thinking, awareness, attention,
learning, judgement and memory.
Diagnosis
To diagnose a stroke a doctor will usually make an assessment using
several of the following:
Examination of current signs and symptoms
Review of medical history
Electrocardiogram (ECG) - measures electrical activity in the heart
Echocardiogram - to asses for any abnormalities in heart function and
structure
Electroencephalogram (EEG) - measures electrical activity in the brain
Ultrasound scanning of the neck arteries (carotids)
Computerised tomography (CT) scan - specialised x-rays that can provide
detailed cross-sectional images of the brain
Magnetic resonance imaging (MRI) - a specialised scan that produces a
detailed image of the brain
Blood tests
Chest x-rays.
Treatment
Stroke is a medical emergency requiring immediate treatment. Prompt
treatment improves the chances of survival and increases the degree of
recovery that might be expected. The treatment given will depend on the
type of stroke suffered.
INITIAL TREATMENT
Immediate treatment is aimed at limiting the size of the stroke and
preventing further stroke. Acute stroke therapies try to stop a stroke
while it is happening by quickly dissolving the blood clot causing an
ischaemic stroke or by stopping the bleeding of a hemorrhagic stroke.
This will involve administering medications and may involve surgery in
some cases.
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Medications
Thrombolytic therapy: These medications dissolve blood clots allowing
blood flow to be re-established
Anticoagulants (eg: heparin): These medications help to prevent blot
clots getting bigger and prevent new blood clots from forming
Antihypertensives: In cases of haemorrhagic stroke these medications may
be prescribed to help lower high blood pressure
Medications to reduce swelling in the brain and medications to treat
underlying causes for the stroke eg: heart rhythm disorders may also be
given.
Surgery
Surgery may be needed to repair blocked or ruptured arteries. For a
haemorrhagic stroke this may involve repairing a bleeding aneurysm or
AVM. Where an ischaemic stroke has been caused by a blockage in a neck
artery surgery to remove the blockage may be performed. This is known as
a carotid endartarectomy.
Supportive treatment
Providing adequate fluid and nutrition intake after a stroke is vital,
particularly if swallowing has been affected. This may require the
insertion of an intravenous drip into a vein in the hand or arm, or it
may involve inserting a feeding tube via the nose into the stomach.
Preventing complications that can occur as a result of immobility eg:
pneumonia and bed sores, is also important.
LONGER TERM TREATMENT:
Brain cells do not generally regenerate (regrow). Following a stroke,
surviving brain cells can take over the function of areas that are dead
or damaged, but only to a certain degree. The adaptive ability of the
brain requires the relearning of various skills.
As each person who suffers a stroke is affected differently, individual
rehabilitation plans are developed in conjunction with the patient,
family and healthcare team. These aim to teach skills and maximise
function so that the person can achieve maximum independence.
Rehabilitation may involve:
Physiotherapy - to improve mobility
Speech therapy - to improve communication
Occupational therapy - to improve daily functions such as eating,
cooking, toileting and washing.
Recovery can take months and it may be several days or weeks after the
stroke before doctors are able to give an accurate prediction for
recovery.
Long term treatment with medications to treat the underlying cause of
the stroke and to minimise the risk of further stroke may be required.
This includes long term use of medications to treat high blood pressure,
heart rhythm disorders, high cholesterol, heart disease and blood
clotting disorders. Common long-term medications prescribed for people
who have had a stroke include warfarin and aspirin - both of which aim
to prevent the formation of blood clots.
Surgery to treat the underlying cause of the stroke may also be
recommended. This can include surgery to damaged heart valve, heart
rhythm problems (may involve the insertion of a pacemaker) or carotid
endartarectomy.
Prevention
Reducing the number of controllable risk factors is the best way to
prevent a stroke. This can include:
Stopping smoking
Losing weight
Eating a balanced diet low in sodium and saturated and trans fat
Moderating alcohol intake (no more than 2 small drinks per day)
Exercising regularly in order to stay physically fit
Maintaining good control of existing medical conditions such as
diabetes, high blood pressure and high cholesterol.
If discovered prior to a stroke, some medical conditions may be repaired
surgically in order to prevent a stroke occurring in the first place eg:
aneurysms, narrowed arteries, heart rhythm disorders, heart valve
problems.
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