Virtual Medical Centre

Stroke (Cerebrovascular accident; CVA)

• What is Stroke?
• Who gets Stroke?
• Predisposing Factors
• Progression
• Probable Outcomes
• How Will Stroke Affect Me?
• Clinical Examination
• How is Stroke Diagnosed?
• How is Stroke treated?
• Stroke References
• Drugs/Products Associated with Stroke

What is Stroke?

3D Animation on Stroke This animation brought to you by Blausen Medical Communications. Contact Andrew Walbank.

Stroke is a disease defined as a sudden neurological deficit (e.g. weakness, loss of sensation or other) due to a vascular cause. The deficit must last for longer than 24 hours and is of sudden onset. There are two main types: Ischaemic (85%): can be due to a thrombus (a clot forming in one of the blood vessels supplying the brain); or due to an embolus - a clot which travels from another site (usually the heart) to block off one of the arteries in the brain. Haemorrhagic (15%): this is due to rupture of one of the arteries in the brain - usually due to an aneurysm (an outpouching of an artery - causing a point of weakness).

There are several other types - including dissection (splitting) of the wall of one of the blood vessels to the brain, or trauma, and others - but they make up a very small percentage. A TIA (or transient ischaemic attack) has the same symptoms as a stroke, but the neurological deficit lasts for less than 24 hours - i.e. the person recovers completely within that time. It is usually caused by a small embolus which is resorbed.

Who gets Stroke?

Stroke is the third most common cause of death in developed countries. It is uncommon before the age of 40 and is more common in males. Stroke affects around 1.2% of Australian patients at sometime in their lives, which corresponds to 217,500 Australians affected. With the growing incidence of obesity in Australia (which contirbutes to stroke through hypertension and atherosclerosis- fatty plaques in blood vessels) the incidence of strokes is expected to sky-rocket by 2050. However, the incidence in younger age groups - eg. 40-60 is dropping with better control of hypertension. Stroke is more common in certain races - eg. Afro-Caribbean.

Men

Men are at greater risk of stroke than women up until the age of 55 years, after which both sexes have similar risks. Stroke is a major cause of morbidity and mortality in the elderly.

Women

Whilst stroke is considered a disease more commonly affecting men, women are actually twice as likely to die from stroke than men. In addition, females have additional risk factors for stroke such as oral contraceptives, that are not present in men.

Children

Stroke is uncommon in children accounting for only a small percentage of stroke cases each year. Stroke in children is often secondary to congenital heart disease (embolic stroke), genetic disorders, abnormalities of intracranial vessels or blood disorders such as Thrombophilia. Half of strokes in children are haemorrhagic and these may be associated with long term disabilities.

Predisposing Factors

The risk factors for ischaemic stroke are similar to the risk factors for coronary artery disease:  

Unavoidable risk factors

Age greater than 60 (risk of stroke doubles every decade), male sex, family history of stroke, racial origin.

Avoidable risk factors

Hypertension, Diabetes, Smoking, Excess Alcohol consumption, Obesity, Lack of exercise.

Women

Prolonged use of the Oral Contraceptive Pill.

The risk factors for haemorrhagic stroke are

Hypertension, anticoagulant drugs, bleeding disorders, cerebral aneurysm.

Progression

Prior to the onset of the stroke, the patient may have previous symptoms due to a TIA -for example transient episodes of weakness on one side or inability to speak, or more commonly - loss of vision in one eye, which usually develops as a "black veil which gradually goes down" - amaurosis fugax. The onset of the stroke is usually sudden, although it can evolve in a step-wise manner over several hours in thrombotic stroke. The deficit lasts for longer than 24 hours. After its development, the neurological deficit may improve gradually over the next few weeks to months, and sometimes it may completely improve, although most patients are left with a residual deficit - often severe. Haemorrhagic stroke also occurs suddenly, though it is usually accompanied by a severe headache. It is more likely to cause coma than ischaemic stroke, due the increase in pressure in the brain.