Stroke can strike silently

Stroke can strike silently
Hypertension, or high blood pressure, is one of the biggest risk factors that can be controlled to reduce the risk of getting a stroke.
Photo: AFP

Getting a stroke can be like getting hit by lightning - it often seems to come out of nowhere and you'll never be the same again after it.

Unfortunately, getting a stroke is not as rare as being hit by lightning; according to the World Heart Federation, stroke is the second leading cause of death in those aged 60 and above worldwide, and the fifth leading cause of death in those aged 15 to 59 years old.

It is also the second leading cause of disability globally, after dementia.

The scenario is equally gloomy in Malaysia with a study published last December in the Journal of Stroke and Cerebrovascular Diseases reporting that the incidence of ischaemic stroke in the country is estimated to increase annually by 29.5 per cent and haemorrhagic stroke by 18.7 per cent.

An ischaemic stroke is caused by an obstruction, e.g. atherosclerosis or blood clots, in the blood vessels that supply the brain, causing a lack of oxygen supply, while a haemorrhagic stroke occurs when a blood vessel in the brain ruptures and bleeds, or haemorrhages, internally.

Ischaemic strokes account for about 80 per cent of all stroke cases.

And according to Universiti Malaya consultant geriatrician Prof Dr Philip Poi, strokes are the greatest cause of disability among older Malaysians.

The symptoms of a stroke are quite dramatic, e.g. drooping of one side of the face, weakness or numbness of the arms and/or legs, especially on one side of the body, slurred or garbled speech, sudden blurring or loss of vision, dizziness, confusion, difficulty understanding what others are saying and problems with balance and coordination.

In a major stroke, these symptoms are permanent, although Prof Poi notes that up to 50 per cent of patients can gain adequate functional recovery if they go through a proper rehabilitation process for more than a year.

However, some stroke symptoms only last for minutes or hours before disappearing completely. These cases are known as transient ischaemic attacks (TIAs), or mini-strokes.

TIAs are usually caused by blood clots obstructing a blood vessel to the brain.

The difference between a TIA and an ischaemic stroke is that the body manages to quickly dissolve the blood clot in the TIA before it does permanent damage.

These mini-strokes can be easy to miss as people might sometimes just brush off episodes of dizziness, confusion, difficulty with speaking, or sudden one-sided numbness or weakness, as due to old age, especially if the symptoms disappear fairly quickly.

However, a TIA is also called a warning stroke as it indicates that there is a problem with the blood supply to the brain.

According to the American Heart Association, about a third of TIA patients will go on to have a major stroke within a year.

White matter disease

There is also another type of stroke that is even more insidious in its presentation.

Called a silent stroke, its symptoms are also often dismissed as signs of old age, as they usually occur in older adults.

According to Prof Poi, these strokes are subtle, both in their presentation and their effect on brain, or cognitive, function.

"It may present in terms of poorer memory, difficulty in finding words, or small, partial weakness in some part of the body, which can be overcome (by compensating with another part of the body), and one of the biggest problems is that these silent strokes become cumulative in their effect.

"When the brain sustains more and more of these strokes, they start to show up in terms of poorer function, like not being able to carry out activities of daily living," he says.

Describing these strokes as resulting from the blockage of "side streets" in the brain, as opposed to the "main streets" in major strokes, Prof Poi says that while the brain is resilient enough to withstand a few of these micro-strokes, the cumulative effect of such strokes will eventually result in poorer brain function.

These silent strokes are a result of what is called white matter disease.

This condition results in the small blood vessels that supply the brain's white matter hardening, thus, decreasing the supply of nutrients and oxygen to this area that functions as the nerve highway within the brain.

The affected areas then become fibrosed, or scarred, resulting in white matter lesions that are more likely to cause electrical miscommunication within the brain, according to Prof Poi.

"This is a phenomenon seen only on magnetic resonance imaging (MRI), and also, sometimes, on CT scans," he says.

"Previously, it was considered a normal finding in older persons, but now, they suspect that if there are white matter lesions in the MRI, the person is more likely to get memory issues, more likely to get dementia and more likely to get strokes."

A 2014 ScienceDaily article, citing materials from the British Psychological Society, said that white matter disease is responsible for about a fifth of all strokes worldwide and more than doubles the future risk of stroke.

Because of the way it presents, silent strokes are very hard to pick up.

Fortunately, the risk factors, and thus, methods of prevention, for all three types of stroke - full stroke, TIA and silent stroke - are the same.

Prevention is better than cure

"Age is the worst risk factor, but you can't reverse that," says Prof Poi.

Hypertension, or high blood pressure, is one of the biggest risk factors that can be controlled, he adds.

Other important factors include smoking, diabetes, an unhealthy diet, insufficient physical activity and high cholesterol levels.

For older persons, Prof Poi shares that atrial fibrillation, or an irregular heartbeat, is another important risk factor for stroke.

"This, unfortunately, becomes more commonly found beyond the age of 80 - about 10-11 per cent of people at the age of 80 develop this irregular heartbeat, which in turn, causes turbulence in the heart, which increases the risk of small clots forming, which can be sent up to the brain, and cause either 'big trouble' or 'small trouble'," he says.

His advice to prevent strokes is to take precautions in midlife, not wait until you are old.

"You have to start protecting your brain by having regular monitoring," he says.

For hypertension, Prof Poi observes that the easiest way to monitor it is also the wrong way.

"It is to come rushing straight back (from work) and check your blood pressure (with a machine at home).

"The right way to monitor your blood pressure is to sit quietly and relax, then check your blood pressure after five minutes," he says.

"And it's like the stock market - it'll go up and down - so please don't get too excited about one (high) reading.

"It has to be three consistently high readings before you can consider you have a problem," he says, adding that a high blood pressure reading is anything over 140/90.

Smoking, a common past-time amongst many people of adult age, is another issue, he says.

"But it is detrimental to the arteries, and can cause higher risk of developing problems that lead to stroke."

Diabetes is another risk factor, which affects about 20 per cent of the adult population.

"And that disease, if not well-controlled, can lead to atherosclerosis and narrowing of the arteries, which can increase the risk of micro-strokes, as well as big strokes," he says.

Aside from consuming a healthy diet and having enough physical activity, Prof Poi shares that taking tocotrienols might also help to prevent strokes, in particular, those caused by white matter disease.

Tocotrienols are one of the two types of vitamin E. It is an increasingly popular dietary supplement, usually sourced from palm oil, which is one of the most naturally-rich sources of tocotrienols.

A 2014 Malaysian study involving 121 volunteers, which was published in the journal Stroke, found that of the two groups involved - all of whom had cardiovascular risk factors and MRI-confirmed white matter lesions - the one that took 200mg of mixed tocotrienols orally twice a day had no further significant growth of their white matter lesions after two years, while the group on the placebo had an average 23.3 per cent increase of their white matter lesions by the end of the same period.

The reason for that can be explained biochemically, says Prof Poi.

Cell death occurs because of glutamate release, he explains.

The body is usually able to remove such glutamate via its own natural glutathione when cells die in the usual small numbers.

However, in white matter disease where the blood supply to parts of the brain is compromised, more cells are affected and larger amounts of glutamate are released, overwhelming the body's glutathione supply and causing further damage to the immediate area.

"Tocotrienols seem to mitigate the effect by reducing the amount of glutamate around," says Prof Poi.

"It's like sprinklers in fire-fighting, if you have it, the place is less likely to burn down."

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