Dr Anjana Kannankara
Stroke is a major global public health problem. It has remained a leading cause of mortality globally in the last 15 years, ranking as the fourth leading killer in the US. India too has witnessed an alarming rise in the occurrence of stroke during the past 25 years. A stroke can be devastating to individuals and their families, robbing them of their independence. It is also the most common cause of adult disability and death.
What is a stroke
A stroke, or ‘brain attack’, occurs when blood circulation to the brain fails. Brain cells can die from decreased blood flow and the resulting lack of oxygen.
Two categories
There are two broad categories of stroke: those caused by a blockage of blood flow and those caused by bleeding into the brain.
Ischemic: A blockage of a blood vessel in the brain or neck, called an ischemic stroke, is the most frequent cause of stroke and is responsible for about 80 percent of strokes. These blockages stem from three conditions:
a) Formation of a clot within a blood vessel of the brain or neck, called thrombosis
b) Movement of a clot from another part of the body such as the heart to the brain, called embolism
c) A severe narrowing of an artery in or leading to the brain, called stenosis
Hemorrhagic: Bleeding into the brain or the spaces surrounding the brain causes the second type of stroke, called hemorrhagic stroke.
Lowering the risk
Two key steps can be taken to lower the risk of death or disability from stroke — control the risk factors of stroke and know and identify the warning signs. Scientific research has identified warning signs and a large number of risk factors as given below. Warning signs are clues which the body sends that the brain is not receiving enough oxygen. If one or more of these signs of a stroke or brain attack is observed, he must seek medical attention immediately which is very crucial.
• Sudden numbness or weakness of face, arm or leg, especially on one side of the body
• Sudden confusion or trouble talking or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness or loss of balance or coordination
• Sudden severe headache with no known cause
• Other danger signs that may occur include double vision, drowsiness, and nausea or vomiting.
• Sometimes the warning signs may last only a few moments and then disappear. These brief episodes, known as transient ischemic attacks or TIAs, are sometimes called ‘mini-strokes’. Although brief, they identify an underlying serious condition that won’t go away without medical help. Unfortunately, since the signs clear up fast, many people ignore them. Paying attention to them can save your life.
Risk factors for a stroke
A risk factor is a condition or behaviour that occurs more frequently in those who have, or are at greater risk of getting, a disease than in those who don’t. Having a risk factor for stroke does not necessarily mean you will suffer a stroke. On the other hand, not having a risk factor does not mean you will avoid a stroke. But one must be cautious that the risk of stroke grows as the number and severity of risk factors increase. Some factors for stroke can’t be modified by medical treatment or lifestyle changes.
Age: Stroke occurs in all age groups. Studies show the risk of stroke doubles in each decade between the ages of 55 and 85. But strokes also can occur in childhood or adolescence. Although stroke is often considered a disease of ageing, the risk of stroke in childhood is actually highest during the perinatal period, which encompasses the last few months of fetal life and the first few weeks after birth.
Gender: Men have a higher risk for stroke in young and middle ages but rates even out at older ages, and more women die from stroke.
Race: People from certain ethnic groups have a higher risk of stroke. For African Americans, stroke is more common and more deadly — even in young and middle-aged adults — than for most other ethnic or racial groups. Studies show that the age-adjusted incidence of stroke is about twice as high in African Americans and Hispanic Americans as in Caucasians. The incidence of the various stroke subtypes also varies considerably in different ethnic groups.
Family history of stroke: Stroke seems to run in some families. Several factors may contribute to familial stroke. Members of a family might have a genetic tendency for stroke risk factors, such as an inherited predisposition for high blood pressure (hypertension) or diabetes. The influence of a common lifestyle among family members also could contribute to familial stroke.
Some of the most important treatable risk factors of stroke are high blood pressure, or hypertension. Hypertension is by far the most potent risk factor for stroke.
• Maintain proper weight. Avoid drugs known to raise blood pressure.
• Eat right. Cut down on salt and eat fruits and vegetables to increase potassium in your diet. Exercise more.
• Take prescribed medicines that help lower blood pressure without fail.
• Controlling blood pressure will also help you avoid heart disease, diabetes, and kidney failure.
Smoking causes about a two-fold increase in the risk of ischemic stroke and up to a four-fold increase in the risk of hemorrhagic stroke. Also, nicotine raises blood pressure; carbon monoxide from smoking reduces the amount of oxygen the blood can carry to the brain; and cigarette smoke makes the blood thicker and more likely to clot.
If a person experiences a TIA, he needs to get help at once. For someone who has previously had a TIA or stroke, the risk of having a stroke is many times greater than someone who has never had one. Hence, it is important to reduce the risk of a second stroke. Since the brain helps recovering from a stroke by asking the unaffected brain regions to do double duty, that means a second stroke can be twice as bad.
Diabetes: In terms of stroke and cardiovascular disease, having diabetes is the equivalent of ageing 15 years. Many think this disorder affects only the body’s ability to use sugar, or glucose. But it also causes destructive changes in the blood vessels throughout the body, including the brain. Also, if blood glucose levels are high at the time of a stroke, then brain damage is usually more severe and extensive than when blood glucose is well-controlled. Hypertension is common among diabetics and accounts for much of their increased stroke risk. Treating diabetes can delay the onset of complications that increase the risk of stroke.
Cholesterol imbalance: Low-density lipoprotein cholesterol (LDL) carries cholesterol (a fatty substance) through the blood and delivers it to cells. Excess LDL can cause cholesterol to build up in blood vessels, leading to atherosclerosis. Atherosclerosis is the major cause of blood vessel narrowing, leading to both heart attack and stroke. Hence keeping the issue under control is absolutely required.
Physical inactivity and obesity: Obesity and inactivity are associated with hypertension, diabetes and heart disease. Waist circumference to hip circumference ratio equal to or above the mid-value for the population increases the risk of ischemic stroke three-fold. Proper exercise plans and reducing the weight can be achieved with the help of a professional.
(The author is director,
TGL Foundation, and
senior director, FWO)