Stroke (cerebrovascular accident)

Written by Professor Marion McMurdo, honorary consultant in medicine for the elderly

What is a stroke?

A stroke occurs when the blood supply to the brain is disturbed in some way. As a result, brain cells are starved of oxygen causing some cells to die and leaving other cells damaged.

Types of stroke

Most strokes occur when a blood clot blocks one of the arteries (blood vessels) that carries blood to the brain. This type of stroke is called an ischaemic stroke.

Transient ischaemic attack (TIA) is a short-term stroke that lasts for less than 24 hours. The oxygen supply to the brain is restored quickly, and symptoms of the stroke disappear completely. A transient stroke needs prompt medical attention as it is a warning of serious risk of a major stroke.

Cerebral thrombosis occurs when a blood clot (thrombus) forms in an artery (blood vessel) supplying blood to the brain. Furred-up blood vessels with fatty patches of atheroma (arteriosclerosis) may make a thrombosis more likely. The clot interrupts the blood supply and brain cells are starved of oxygen.

Cerebral embolism is a blood clot that forms somewhere in the body before travelling through the blood vessels and lodging in the brain. This causes the brain cells to become starved of oxygen. An irregular heartbeat or recent heart attack may make you prone to forming emboli.

Cerebral haemorrhage occurs when a blood vessel bursts inside the brain and bleeds (haemorrhages). With a haemorrhage, extra damage is done to the brain tissue by the blood that seeps into it.

What are the effects of a stroke?

No two strokes are the same and people can be affected in quite different ways. This partly depends on which area of the brain is damaged, because different parts control different abilities such as speaking, memory, swallowing and moving.

Strokes usually occur suddenly.

The most common signs of a stroke are weakness, paralysis or numbness of the arm and leg.

Speech may be difficult or become difficult to understand.

Swallowing may be affected. Until this improves, patients may be fed by a tube or given fluids into a vein (intravenously) to avoid food going into the lungs.

People who have had severe strokes may lose consciousness. Unfortunately, the likelihood of such patients making a good recovery are poor.

How is a stroke treated?

In the first few days after a stroke, treatment involves ensuring that the patient is well hydrated and nourished. The next phase of treatment - recovery through rehabilitation - involves a team of health professionals including physiotherapists, speech therapists, occupational therapists, nurses and doctors.

If a stroke is caused by a blood clot, then taking a low-dose aspirin (eg Nu-seals 75mg) once a day may help make the blood less sticky and less likely to cause clots.

What are the risk factors?

High blood pressure (hypertension) does not cause any symptoms, so everyone over the age of 40 should have an annual blood pressure check.

Smokers have double the risk of stroke as non-smokers.

Irregular heart beat (atrial fibrillation) is fairly common in old age, and increases the risk of stroke by causing blood clots to form in the heart. Blood clots can be prevented from forming by taking warfarin, a medicine that makes the blood less likely to clot. Warfarin treatment requires careful monitoring with regular blood checks and is a very effective way to reduce the risk of stroke.

Diabetes affects 1 in 20 older people, and can also increase the risk of having a stroke. Good control of diabetes is important and requires attention to diet, regular urine tests or blood tests, and probably some medication.

Too much alcohol increases the risk of a stroke. The recommended 'safe' limits for alcohol consumption are 21 units each week for women and 28 units each week for men. One unit of alcohol is equivalent to a measure of spirits, or a glass of wine, or half a pint of beer. People who drink more than this run a higher risk of stroke, liver disease and dementia.

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