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Truths and myths about stroke
WITH increasing longevity, stroke has become an increasingly important cause of morbidity and mortality. The good news is that advances in medicine have made it easier to prevent stroke and made it possible to provide good therapeutic options.
Types of stroke
Generally, strokes can be divided into two main categories, namely ischaemic (due to insufficient blood supply and oxygen) or haemorrhagic (due to bleeding in the brain). A ischaemic stroke is due to severe narrowing of the arteries to the brain, the occlusion of a brain artery by a blood clot, a combination of both , clotting of the veins in the brain or embolic material (cholesterol particles or blood clot that have dislodged and have travelled in the circulation to the brain to occlude a vessel).
A hemorrhagic stroke can be due to rupture of a brain artery aneurysm (swelling of a segment of the artery), rupture of an abnormal vessel in the brain (such as cavernoma or arteriovenous malformation) severe hypertension, trauma or consumption of blood thinning agents.
We examine the following statements to find out whether they are true or false.
*Stroke is rare in the young Contrary to popular belief, epidemiological evidence has shown that the incidence of a stroke in the young has increased significantly in the past decade. Some studies show that up to 15 per cent of all brain infarcts occur in young adults (ages 18 to 50 years). The 2017 Singapore Stroke Registry data in Singapore showed a similar trend with the incidence rate of stroke increasing in those from ages 15 to 59 years. Annual incidence rates of stroke in Singapore in 2017 ranged from 5.2 (in those aged 15 to 29 years) to 231 (in those aged 50 to 59 years) per 100,000 population.
* Stroke is part of ageing
In those 60 years and above, in the 2017 Singapore Stroke Registry, the incidence rate per 100,000 population has been decreasing over the past decade. What this means is that understanding the risk factors that can cause a stroke can help a person make the necessary lifestyle changes to reduce the risk of a stroke.
Hypertension and high cholesterol remain the commonest risk factors for stroke, being present in about 83 per cent of the Singapore stroke cohort. Nearly half of the Singapore stroke cohort have risk factors such as diabetes mellitus (41 per cent) and the presence of heart artery disease (46 per cent). Other important risk factors include smoking (36 per cent), and an abnormal heart rhythm called atrial fibrillation (21per cent) .
* Stroke can be prevented
Stroke can mostly be prevented by controlling risk factors. Lifestyle factors such as cessation of smoking, reducing salt intake and reduction of intake of saturated fat are beneficial. Home blood pressure is one of the most accurate ways to assess your true blood pressure. If your blood pressure reading is consistently more than 140 mm Hg over 90 mm Hg, you should see a doctor to keep the blood pressure within the acceptable recommended limits.
If you are a diabetic, frequent small meals are better than a few large meals and recording your sugar response to different types of food will help you to make better decisions on your food choices. There is a sugar monitoring sensor attached to a plaster which can be attached to the back of your arm which can constantly allow you to monitor your sugar response to different foods.
Use of this monitoring system can help diabetics make better decisions on food choices and improve blood sugar control. If you have high cholesterol levels, you should consult your doctors on the need to start statins.
* Calcium supplementation is safe
While many take calcium supplements to reduce osteoporosis, studies have shown that excessive dietary calcium intake from consumption of calcium supplements can lead to adverse health consequences.
Calcium supplement consumption results in a sudden elevation in the calcium level in the blood which can lead to an increase in the calcium level in the urine (which can lead to stone formation) and deposition of calcium in soft tissue and walls of arteries. A 2014 study by Gallagher, published in Menopause journal, found that calcium supplementation in women resulted in excessively high blood calcium levels in 9 per cent and excessively high urine calcium level in 31 per cent.
Randomised controlled studies, including the Women's Health Initiative, have shown an association between calcium supplement use and increased risk for heart disease and strokes. A study on long term calcium intake in the community by Michaelsson, published in the British Medical Journal in 2013, showed that a high intake of calcium supplements greater than 1,400 mg/day was associated with higher death rates from all causes, including heart disease and stroke. While dietary consumption of calcium supplements has been shown to be associated with adverse effects, dietary consumption of calcium from food has not been shown to be harmful.
* Stroke can be caused by heart disease
In the 2017 Singapore Stroke Registry, nearly half of all the stroke patients had underlying heart artery disease. Hence, those with known heart artery disease will have a high risk of stroke. Patients with heart artery disease should seek their doctor's advice on the need for further assessment for stroke risk.
The Singapore data also showed that one in five stroke patients had an underlying abnormal heart rhythm called atrial fibrillation. In atrial fibrillation, the upper heart chamber beats at a rate of about 400 per minute and the beats are intermittently transmitted to the lower pumping chambers resulting in an irregular rhythm.
The fast heartbeat results in "quivering" of the left upper chamber and slowing down of blood flow resulting in an increased propensity to form blood clots. If the clot forms and travels to the brain arteries, it will result in a stroke. Recognising this and seeking early treatment can help to prevent a stroke.
Remember the following measures to prevent stroke:
1) Stop smoking;
2) Keep your blood pressure not higher than 140/90 mm Hg;
3) Optimise your diabetic control;
4) Keep your LDL cholesterol ("bad" cholesterol) low;
5) Avoid taking calcium supplements;
6) Drink at least two litres of liquids a day to keep yourself hydrated (many strokes are caused by blood clot formation);
7) If you have frequent palpitations or irregular heartbeats, see a doctor to check for atrial fibrillation;
8) If you have heart disease, consult your doctor about your stroke risk;
9) If you are taking blood thinners, seek your doctor's advice on minimising the risk of sudden brain bleeding.
Should a stroke occur despite taking preventive measures, do remember the following:
1) If you have drooping of your face, are unable to lift up your arm normally, or have slurred speech, call for an ambulance immediately;
2) Expect doctors to do a brain scan to confirm the presence of a stroke and to check for bleeding in brain;
3) If the stroke is caused by clots to the brain arteries, the options of infusing blood clot dissolving drugs or insertion of special tubes through the limb arteries to remove the clots may be offered - discuss with the doctors regarding the pros and cons of the options;
4) All these measures should optimally be performed within three hours to get the best outcome.
If you take all the preventive measures, the risk of a stroke will be low. Nevertheless, if a stroke should occur, getting to the hospital speedily via an ambulance will give you the best chance for a good outcome.
This series is produced on alternate Saturdays in collaboration with Singapore Heart, Stroke & Cancer Centre.