Stroke

Stroke, or brain attack, is a cardiovascular disorder that occurs when a blood vessel supplying oxygen to the brain bursts or becomes blocked. Once deprived of oxygen, the nerve cells in the brain cannot function and begin to die, thus impairing the functions of those parts of the body that they can control.

There are two main types of stroke:

Ischaemic Stroke

Ischaemic stroke accounts for approximately 80% of all strokes. It occurs when blood supply to the brain is disrupted due to an obstruction in one or more blood vessels. Such obstruction often occurs in one of the two carotid arteries in the neck carrying oxygenated blood from the heart to the brain.

A blood clot may also develop at other locations in the body and travel through the bloodstream until it lodges itself in a blood vessel, which is already narrowed by a pre-existing condition such as atherosclerosis.

About 10% of ischaemic strokes are preceded by transient ischaemic attacks (TIAs). These are mini-strokes arising from a temporary interruption of blood supply to the brain. They usually last for only a few minutes, and most of their symptoms disappear completely within 24 hours.

Haemorrhagic stroke

Less common is haemorrhagic stroke, which occurs when one or more blood vessels in the brain rupture. Blood leaking from the ruptured vessel compresses other vessels nearby and eventually forms into a clot, cutting blood supply to the surrounding brain tissue.

In general, a haemorrhagic stroke tends to affect a larger area of the brain than an ischaemic stroke, resulting in greater impairment of the victim’s bodily functions. High blood pressure is a very important contributing factor in haemorrhagic stroke.

Symptoms

The symptoms of both types of stroke are similar, although those of haemorrhagic stroke may be more sudden and severe.

Common symptoms include:

• Weakness and/or numbness on one side of the body
• Slurred speech
• Loss of vision in either or both eyes
• Giddiness
• A sudden, severe headache
• Drowsiness, followed in some cases by coma
• Unsteadiness and loss of muscular coordination

The symptoms experienced by a stroke victim vary depending on the size and location of the blood clot, which precipitates the stroke. For some patients, symptoms may occur suddenly; for others, they may develop slowly over several hours or even a few days.

Causes

The main risk factors for stroke are:

• Age
• High blood pressure (hypertension)
• High levels of LDL (bad) cholesterol
• Diabetes
• Smoking, including passive smoking
• Excessive alcohol consumption
• Atrial Fibrillation

All of these factors contribute to atherosclerosis (hardening of the arteries), increasing the likelihood of an ischaemic stroke. Similarly, these risk factors may cause blood vessels to weaken, resulting in a haemorrhagic stroke.

Prevention

Although some risk factors (for instance, age) cannot be altered, the majority can be reduced by adopting healthy living practices such as:

• Monitoring your blood pressure regularly and seeking prompt medical treatment if you are hypertensive
• Having your blood sugar and cholesterol levels tested periodically
• Maintaining a healthy body weight
• Eating a healthy, well-balanced diet
• Incorporating regular exercise into your daily routine
• If you are a smoker, giving up smoking
• Avoiding or stopping drug and alcohol abuse

Taken together, these measures can go a long way in preventing stroke.