A stroke, also known as a Cerebrovascular Accident (CVA), is damage to
the brain tissue due to a problem with its blood supply.
Different parts of the brain have different functions, and are supplied by
different blood vessels. The symptoms of a stroke depend upon which area is
affected. In general, one half of the body is controlled by the opposite side
of the brain. Therefore, for example, damage to a part of the left side of the
brain may result in a paralysis of the right arm. Stroke is common, and
most strokes happen to older people. They are more likely to occur in people
with diseased blood vessels, for example smokers.
Definition:
Rapidly developing clinical signs of a disturbance in cerebral function
with no explanation other than of vascular origin.1
130 000 people in the UK suffer a stroke every year and it
accounts for 5% of the NHS budget2.
The incidence is quoted as 1.5 strokes per 1000 population per year. Among
people over 75 years of age, this rises to 1% per year3. It is the
third most frequent cause of death in the UK after heart disease and
cancer4.
Cause:
The damage to the brain is a consequence of either vessel occlusion (ischaemia) or vessel rupture (an intracerebral
haemorrhage). An occlusion may be due to local thrombus
formation or embolism. In the UK, 10 % of strokes are
haemorrhagic. In Japan, they are much more common.
Risk Factors:
As stroke is a vascular pathology, atherosclerosis is
a common origin for the problem. Many of the risk factors are risk factors for
atherosclerosis.
Indicators of existing vascular and haematological disease are also
important.
And, of course, drugs:
Presentation:
Peak onset is in the early hours of the morning. Focal neurological deficit
develops over minutes, often with no loss of consciousness. Deficit often
follows a step-wise progression over hours or days.
Symptoms include: sensory loss (numbness), hemiplegia (weakness or
paralysis on one side of the body), dysarthria (difficulty articulating
words), aphasia or dysphasia (difficulty with language), ataxia (lack of
coordination), apraxia (difficulty planning tasks), homonymous hemianopia
(loss of the half the visual field)
A history and examination is often sufficient to make the diagnosis. When a
stroke is suspected, a CT scan is usually performed. The CT changes of an
ischaemic stroke don't appear for the first 12 hours, but a haemorrhagic stroke
will be evident as a white area.
Classification:
A useful way of classifying strokes was devised by Bamford in 1991.
Total Anterior Circulatory Infarct (TACI)
Caused by an occlusion of the Middle Cerebral Artery, A TACI will cause:
- higher cerebral dysfunction AND
- hemianopia AND
- motor
and sensory deficit (on the same side) involving at least 2 out of 3 of face,
arm or leg.
Approximately 15% of strokes are of this type. Mortality at one year is >
50%.
Partial Anterior Circulatory Infarct (PACI)
This will cause:
- higher cerebral dysfunction alone OR
- 2/3 features of a
TACI
PACI is most frequently caused by embolus. It is in a smaller branch of the
Middle Cerebral Artery or the Anterior Cerebral Artery. These patients carry a
high risk of recurrence within the first 3 months. Approximately 35% of strokes
are this type.
Lacunar Infarct (LacI)
This is caused by occlusion of a deep perforating artery affecting structures
more central in the brain. It is not as severe as the above two types, and will
not affect the higher brain functions. These patients often make a good
recovery. Approximately 25% of strokes are of this type.
Posterior Circulatory Infarct
This is caused by occlusion in an artery supplied by the vertebrobasilar
circulation, that means the infarct will be in the cerebellum, and/or brainstem
and/or occipital lobe.
Symptoms are many and varied (e.g. hiccups, dysarthria, dysphasia, coma,
vertigo, vomiting, nystagmus, ataxia, diplopia, hemianopia). Sensory
or motor symptoms may be unilateral or bilateral. Approximately 25% of strokes
fall into this category.
Management:
Immediate
Unless there is a suspicion of a haemorragic stroke, 300mg aspirin should
be administered. Thrombolysis within 3 hours of onset of symptoms has been known to help,
and may become standard practice in the future. Currently, few centres have the
facilities to assess the patient's suitability and do it in time. It is still being evaluated. A CT scan of
the head will be performed to rule out haemorrhage. The patient should be kept
Nil by mouth until their swallowing is assessed. Hydration should
be maintained intravenously. Blood pressure should be
monitored, but high levels will not be treated because this will impair
cerebral perfusion. A urinary catheter will be considered if mobility is
impaired. Several investigations are used to exclude an alternative diagnosis or
to identify the reason for the stroke. These include blood tests (e.g. blood
glucose, ESR, and full blood count),
echocardiogram, chest x-ray and ECG.
Rehabilitation
Referral to a stroke unit is beneficial. Here, Physiotherapy, Speech and
Language Therapy, Occupational Therapy, Social work, Dietitian input
Medical and Nursing care are provided by a team of people who
communicate regularly with each other as well as the patient and family.
Examples of the input these professionals have in helping a person who have
suffered a stroke are:
- The physiotherapist exercises the patient, and assesses and optimizes
their balance, strength, and walking.
- The Speech and Language Therapist assesses their speech, language, and
swallowing, and provides exercises to improve these.
- The Occupational Therapist evaluates the level of functioning when
performing everyday necessary tasks, and assesses the need for equipment that
may help with these e.g. bathrails.
- A social worker identifies and negotiates placement of a patient after they
leave the acute hospital, works out where there's funding for this, and also arranges respite for
carers.
- Dietitians deal with nutrition. This can be difficult if swallowing is not
possible. They are also involved if alternative routes of feeding (such as a Nasogastric
tube, or PEG) are required.
- A doctor will often stand as chairman in the team meetings. He/she also
deals with any medication the patient may need, often in consultation with a
pharmacologist.
- Nursing care of people who have suffered a stroke can be pretty intensive. They may be incontinent, immobile, and difficult to communicate with. Special care must be taken of their skin. Also the shoulder of a person with arm weakness or numbness needs particular attention when positioning or moving them. The nurses also monitor a patient's wellbeing and clinical signs.
As you may have gathered, all this involves alot of work from the patient.
Prognosis:
40% achieve a fully recovery3. Drowsiness suggests a poorer
prognosis. The overall mortality is 20% at 1 month, 5 - 10% per year
thereafter.
Depression can be a prominent consequence of stroke, but is treatable.
Stroke also predisposes to pneumonia, and of course bed sores. It is a
stressful event for the whole family. Morbidity is variable, and differs according to the type of stroke. The outcome varies from death through all levels of disability to a full recovery. Many people will continue to suffer from falls, incontinence, and difficulty communicating. After a hospital stay of weeks or months, there is often much rehabilitation still to go. A great proportion of improvement happens in the initial stages.
Prevention:
Modifiable risk factors such as smoking, hypertension, Diabetes and high
cholesterol should be treated. Exercise helps with the cholesterol and
diabetes. People who have had a stroke or a TIA in the past, and don't have
a contraindication to it, should take 75 mg aspirin per day to prevent
stroke. Prevention of a second stroke after you've already had one is called
'secondary prevention'. In the case of a stroke that was clearly caused by an
embolus, this may involve warfarin instead of aspirin. Similarly, risky
conditions like atrial fibrillation and replacement heart valves should be
treated optimally with anticoagulation. In people with demonstrable carotid
artery stenosis, carotid endarterectomy (surgery) should be considered.
1. WHO, Hatamo, 1976
2. Sarah Keir, Western General Hospital,
Edinburgh
3. Oxford Handbook Clinical Medicine 5th ed.,
OUP, pages 323 - 348
4. chapter 7, lecture notes on
geriatric medicine sixth edition, blackwell
publishing