Q: What is a stroke?
A stroke is a sudden loss of bodily functions such as movement, speech, vision, balance, etc that are controlled by the brain. It occurs when a blood clot blocks a blood vessel feeding the brain which we call an ‘ischaemic stroke’ or when a blood vessel bursts which is referred to as a ‘haemorrhagic stroke’, interrupting the blood flow to an area of the brain. 80% of all strokes are ischaemic. In both types of stroke, brain cells are damaged. What should be remembered is that strokes occur suddenly and the effects of stroke manifest rapidly over minutes to hours.
Then there are ‘Transient Ischaemic Attacks’ (TIA). They manifest identical to strokes, but unlike strokes, the symptoms resolve completely within 24 hours. However, TIAs are important to recognize since they are a warning sign that a person is at a high risk of a stroke. Prompt medical attention and treatment reduces the risk of a stroke after a TIA.
Q: How are the effects of a stroke manifested?
Stroke is very often associated with paralysis, but is not so always. Manifestation or effects depend on the area of the brain affected by the stroke. While one may lose the ability to move one side of the body resulting in a paralysis, another may lose the ability to speak or a number of other functions controlled by the brain.
Q: How serious is the situation of stroke locally and globally?
Stroke is the second most common cause of death worldwide. However, mortality data underestimate the true burden of stroke since the major burden of stroke is chronic disability rather than death. About a third of stroke survivors are functionally dependent at one year after stroke. Stroke also causes secondary medical problems such as dementia, depression, epilepsy, falls and fractures. About one in four men and one in five women suffer a stroke if they live to be 85 years old.
Stroke is the fourth leading cause of death here at home and a major cause of disability. Stroke prevalence in Sri Lanka is about 10 per 1000 population but the exact figure depends on the population age and sex structure, incidence, and survival which may vary by time and place. For example, in a recent study done in the district of Colombo, the prevalence of stroke was found to be high among males with the highest prevalence being in the 65-74 years age group. In case of women, the highest prevalence was in the age group of 75 years or older.
Q: What are the risk factors for stroke?
Risk factors for stroke could be classified as ‘modifiable’ and ‘non-modifiable’. Modifiable risk factors are high blood pressure, diabetes, dyslipidaemia (abnormal amounts of lipids. e.g., total and LDL-cholesterol in the blood), heart disease such as an irregular heart rhythm (atrial fibrillation), sedentary lifestyle with lack of exercise, and lifestyle habits such as smoking and excess alcohol. Of these, the most important modifiable risk factor for stroke is high blood pressure.
Non-modifiable risk factors are age and sex. Of these, age is the strongest non-modifiable risk factor. Overall stroke incidence at age 75 – 84 is approximately 25 times higher than at age 45 – 54.
Q: Does stroke in a family member increase one’s risk of stroke?
If a first degree relative (parent or sibling) has had a stroke at an early age (before the age of 55 years), it may suggest a rare genetic cause of stroke such as hereditary dyslipidaemia, certain inherited heart and blood vessel diseases that predispose to stroke or a genetic predisposition to increased blood clotting (known as thrombophilia). If there is such a family history of stroke, one should get tested for these rare causes.
Q: Today we see many young people suffering stroke. What are the reasons for this?
Strokes could occur either due to the traditional risk factors or due to rare genetic risk factors. The traditional risk factors are often the cause in older patients. However, when strokes occur in the young (before the age of 55 years), rare genetic causes may be more evident. As such, strokes in the young, particularly if they do not have traditional risk factors, would be more extensively tested for the rare causes of stroke. It also must be remembered that even after extensive investigation, there is a group of people in whom we may not find a cause or risk factor for stroke. Such are called ‘cryptogenic strokes’.