The Cardiovascular System|
Synonyms : Apoplexy; Cerebral Infarction; Cerebral Vascular Accident, Cerebrovascular accident
accident (stroke) refers to damage to brain tissue due either to cerebral infarction (80-85%) or cerebral
haemorrhage (15-20%). Stroke is uncommon below the age of 50 and affects
males more often than females. It is one of the commonest causes of death in
developed countries and also a prominent cause of disability, particularly in
the elderly. The most common vascular disorder underlying stroke is atherosclerosis
affecting intracranial and extracranial arteries, less common causes are embolism and aneurysms
(pouch-like dilations) of major arteries.
The major risk factors for stroke:
arrhythmias, history of myocardial infarctions (risk for intracardial
Mechanisms of stroke:
stroke). Thrombosis at the
site of atheromatous degeneration in a major cerebral vessel is probably the
commonest mechanism, but embolism of
thrombotic or atheromatous material from the heart or an extracranial artery
is also frequent. Cardiac emboli (arising from mural thrombus after myocardial
infarction, or associated with atrial fibrillation) tend to be large and cause
usually major strokes. By contrast, emboli arising from the carotid artery are
more often smaller, and cause minor strokes or transient cerebral or ocular
symptoms (transient ischaemic attacks). Once completely deprived of blood
supply cerebral tissue undergoes infarction
within a few minutes, the resultant cerebral
oedema causes more damage by compressing blood vessels and further
impairing cerebral blood flow.
Cerebral haemorrhage. The primary cause of cerebral haemorrhage is hypertension. About half the strokes caused by cerebral haemorrhage are due to subarachnoid bleeding, and the other half due to intracerebral bleeding into the brain tissue. Intracerebral bleeding is usually caused by rupture of small intracerebral arteries or arterioles weakened by hypertension and/or atheromatous degeneration. This type of stroke is more likely to occur during physical exertion or emotional stress when blood pressure is increased. On the other hand spontaneous (non-traumatic) subarachnoid haemorrhage usually results from a ruptured aneurysm of one of the major cerebral arteries or their branches, or inborn arteriovenous malformation (a mass of tangled, dilated blood vessels in which small arterioles flow directly into venules without a capillary network in-between). Aneurysms can be saccular (berry) which are thought to arise as a result of congenital defects in the media (muscle layer) of arteries at branch points and fusiform (spindle-shaped) which are a result of atherosclerotic weakening of blood vessel walls. The saccular aneurysms can be found in approximately 1% of the general population when they cause no problems until they burst, when no obvious precipitating factor is usually apparent. Haemorrhage from ruptured fusiform aneurysms often occurs during exertion (e.g., physical activity, sexual intercourse) when blood pressure is increased.
Clinical features: < BACK TO TOP >
usually evolve rapidly over a few minutes, and reach maximum disability within
an hour or two.
precise features of a stroke depend on the vascular territory involved and
mechanism of stroke.
majority of patients with ischaemic stroke exhibit greater or lesser degrees
of hemiplegia (paralysis of the limbs and trunk on the contralateral
side of the body), dysphasia
(impaired coordination of speech - if the left hemisphere is involved), with hemianaesthesia
(loss of sensation on the contralateral side of the body) and homonymous
hemianopia (loss of vision in either
the whole left or the whole right half of the visual field) in some.
the paralysed limbs may be flaccid and reflexes can be decreased, but after a
few days, tone usually increases and reflexes become hyperactive on the
affected side (the signs of upper motor neuron damage).
Headache is a common feature and it is due to secondary brain oedema and
increase of intracranial pressure.
Epileptic seizures, vomiting and depressed consciousness may also occur, the latter
usually indicating a severe lesion and marked increase of intracranial
brain stem lesions may also show dysphagia (difficulty in swallowing), facial
numbness/weakness on the same side as the lesion, and often loss of
consciousness because of damage to the reticular activating system.
patients the symptoms worsen gradually or in a step-wise fashion over a matter
of hours or days (‘evolving stroke?/i>).
patients with brain infarction consciousness is preserved in contrast to
haemorrhage in the brain when the patients suddenly develop signs of increased
intracranial pressure, including severe headache (with neck pain and
stiffness in subarachnoid haemorrhage), nausea and vomiting, and rapid loss of
neurological signs in cerebral haemorrhage may be present but are often
difficult to detect in the setting of a massive elevation in intracranial
pressure and coma.
of the condition is associated with evidence of brain stem compression,
including deep coma; irregular, intermittent respirations (Cheyne-Stokes
respiration); bradycardia and hypertension; dilated, unresponsive pupils; and
spasticity of skeletal muscles.
Transient ischaemic attack (TIA) is an episode of focal neurological dysfunction due to cerebral ischaemia in which symptoms last less than 1 hour, often only a few minutes. It is due to minor embolism from the extracerebral arteries (carotid and vertebral) and less commonly from mural thrombi that develop in heart chambers. Certain patients present with vertigo (dizziness), diplopia (seeing in duplicate) and ataxia (loss of motor coordination commonly presenting as unsteady gait); in others symptoms and signs are similar to completed stroke only milder and transient. TIAs are important because they may herald a completed stroke (approximately one third of patients with TIAs develop clinically significant strokes within 5 years).
Diagnosis: < BACK TO TOP >
clinical diagnosis of stroke is usually straightforward, but can not help in
identifying the cause.
scanning and MRI scanning provide the only reliable method of distinguishing
cerebral infarction from haemorrhage, and are the most commonly used.
may exacerbate the symptoms of stroke caused by infarction and intracerebral
haemorrhage and is done only when the diagnosis is in doubt or surgical
intervention is likely to result; on the other hand if subarachnoid
haemorrhage is proven, urgent cerebral angiography is usually indicated,
followed by neurosurgery to repair the bleeding site.
puncture will usually reveal uniformly blood-stained CSF in subarachnoid
haemorrhage or intracerebral haemorrhage that extends into the subarachnoid
(ultrasound examination of the heart) is sometimes performed if there is a
suggestion of a cardiac source of embolism causing stroke.
Carotid Doppler ultrasound scanning can reveal alteration of blood flow due to atheromatous and thrombotic lesions.
Management < BACK TO TOP >
specific treatment is available which can reverse the brain damage.
airway maintenance, adequate oxygen, intravenous fluid to maintain
nutritional and fluid intake, careful nursing to prevent bed sores and
physiotherapy to prevent joint contractures are needed.
tissue plasminogen activator [Actilyse, Rapilysin] given within few hours of
symptom onset can improve the outcome in certain ischaemic stroke patients;
anticoagulation with heparin may be beneficial to patients with evolving
inhibitors of platelet aggregation (aspirin) can be used for stroke
prevention, especially in patients suffering frequent TIAs.
of stroke caused by intracerebral haemorrhage is similar, except that
thrombolytics, anticoagulants and antiplatelet drugs are contraindicated;
rarely surgical evacuation of large haemorrhages (intracerebral haematoma) is
attempted with high mortality rate, but subarachnoid haemorrhage must be
treated surgically, with very high success rate.
patients who survive show some degree of recovery which is maximal in first 6
months; usually no significant improvements can be expected after 1 year.
Rehabilitation to restore mobility is planed and carried out, and this is usually a very long process.
Prognosis < BACK TO TOP >
Nutrition < BACK TO TOP >
Nutrition that alleviate or prevent Stroke :-
Herbs < BACK TO TOP >
Herbs that alleviate or prevent Stroke :-
(source : -)
speaker Mr NgThian Watt the Principal Trainer from
Napoleon Hill Associates MalaysiaDetails