By Assoc Prof Dr Tan Kay Sin

STROKE is a common cause of adult disability and the second most common cause of death worldwide after coronary heart disease. The proportion of deaths caused by stroke is 10% to 12% in Western countries while 12% of these events occur in those under 65 years of age.

In the year 2002, stroke was the sixth largest cause of disability. This is measured by reduced disability-adjusted life-years (DALYs); in short, this scale is a measure of the number of years lost prematurely and the number of years lived in disability.

Stroke is also responsible for 9% of all deaths worldwide. In Western societies, it is estimated that stroke will be the fourth most important cause of reduced DALYs.

Stroke also consumes an estimated 2% to 4% of total healthcare costs worldwide.

'Brain attack': Symptoms

While members of the public are well aware of heart attack symptoms such as sudden onset of chest pain, breathlessness, and sweating, they are not so aware that patients suffering from a stroke or "brain attack" may experience:

• sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
• sudden confusion with trouble speaking or understanding
• trouble walking due to loss of balance or incoordination.

As most of these episodes are painless, it is one of the reasons why medical evaluation and treatment is often delayed in strokes.

Overall, strokes are the result of symptoms and signs from a number of possible underlying disease processes or simplistically "causes". These factors need to be identified and the mechanisms understood in order to minimise brain damage in the early phase of stroke and to prevent recurrence.

The public should be aware that stroke by itself is not a complete diagnosis without understanding the mechanism. This is important to prevent recurrence and to institute proper therapy.

Risk factors

The public should also be aware of the important concept of stroke risk factors. The presence of these medical problems puts the patient at greater risk compared to the normal population. This can be broadly classified as modifiable or non-modifiable. Age and gender are examples of non-modifiable risk factors. Modifiable risk factors such as diabetes, hypertension, high blood lipids, and smoking are common and offer ample opportunities to alter stroke risk in large populations. This fact should be emphasised time and time again.

Other less common risk factors for stroke, such as atrial fibrillation (abnormal, irregular heart rhythm) and transient ischaemic attacks (mini-strokes or near strokes with complete recovery) are also important.

Interestingly, the above risk factors or traditional risk factors can explain only 60% of strokes. On the other hand, these identifiable risk factors can elucidate up to 90% of coronary heart disease. Research is ongoing to explain the 30% difference between strokes and heart disease. Some of these unexplained risk factors may be genetic or as yet undiscovered.