Stroke - symptoms, diagnosis, treatment, prevention
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.
Types of 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 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.
People of all ages and genders can suffer a stroke. In New Zealand approximately 22 people have a stroke each day.
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:
- Male gender
- Family history
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:
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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
- 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
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
- Emotional problems, such as difficulty controlling emotions or expressing inappropriate emotions.
Stoke may also cause problems with thinking, awareness, attention, learning, judgement and memory.
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.
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.
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.
- 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 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.
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.
Reducing the number of controllable risk factors is the best way to prevent a stroke. This can include:
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.
The Stroke Foundation Of NZ Inc. offers information and support and can provide details for regional branches. Contact details are as follows:
Stroke Foundation of NZ Inc
Freephone: 0800 STROKE (0800 78 76 53)
Allen, C.M.C. and Lueck, C.J. (1999). Diseases of the nervous system. In C. Haslett, E.R. Chilvers, J.A.A. Hunter & N.A. Boon (eds.) Davidson’s principles and practice of Medicine (18th ed.) (pp9231023- 1023) Edinburgh: Churchill Livingstone
Neurological Foundation of New Zealand (2013) Stroke. Neurological Foundation of New Zealand. Auckland http://www.neurological.org.nz/disorders/stroke
Robinson, R. and Ogle, T. G. (2006) Stroke. The Gale Encyclopaedia of Medicine. Third Edition. Jacqueline L. Longe, Editor. Farmington Hills, MI. Thompson Gale.
Stroke Foundation of New Zealand (Date Unknown). Understanding and preventing stroke and TIA. (Booklet) Stroke Foundation of New Zealand Inc.
Last Reviewed – 26 June 2013
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