The kinds of stroke: how they happen and how they harm your health
Posted on 9 September 2019
Ischaemic and haemorrhagic strokes and transient ischaemic attacks all affect the body differently. They can be caused by clots or ruptured blood vessels – and in some cases, like cryptogenic strokes, the cause remains a mystery.
A brain attack (stroke) occurs when a blood vessel that carries oxygen and nutrients to the brain is blocked by a clot, or the vessel ruptures. When either of these events happen, brain cells die because they cannot receive the blood and oxygen they need. The 2018 STATS SA report on mortality states that conditions affecting the blood vessels in the brain are the second leading cause of death in South Africa. ‘Anyone could be at risk of having a stroke,’ says Dr Melanie Stander, Mediclinic’s Emergency Medicine Manager. ‘While you can’t change certain factors – like getting older or having a family history of stroke or heart disease, you can change unhealthy habits. These include smoking, being overweight or not exercising enough. Regular screening for chronic diseases like diabetes and hypertension is also very important.’
There are two main types of stroke – ischaemic and haemorrhagic and they can affect the body differently. The way a stroke can affect you depends on where the stroke occurs in the brain and how much of the brain is damaged. Your speech, movement and / or memory might be affected.
Ischaemic strokes account for the majority of brain attacks and occur when a blood vessel in the brain is blocked by a blood clot or a build-up of fatty deposits. This build-up can cause two types of obstruction:
Cerebral thrombosis is a thrombus (blood clot) that develops at the fatty plaque within the blood vessel. Cerebral embolism is a blood clot that forms in the heart and large arteries of the upper chest and neck. Part of the blood clot dislodges, enters the bloodstream and travels through the brain’s blood vessels until it reaches vessels too small to let it pass.
Haemorrhagic strokes happen when a blood vessel in your brain bursts, causing blood to accumulate in surrounding tissue.
The most common cause of a haemorrhagic stroke is hypertension.
Other causes include two types of weakened blood vessels known as aneurysms (a ballooning of the blood vessels) and arteriovenous malformations (AVMs), which are a cluster of abnormally formed blood vessels.
Haemorrhagic strokes are either intracerebral (within the brain) or subarachnoid (in the areas surrounding the brain).
A Transient Ischaemic Attack (TIA) is less severe than a full-blown stroke. According to the Heart and Stroke Foundation South Africa, most TIAs usually last a short time (10 -15 minutes) and sufferers usually recover within 24 hours without permanent damage to the brain.
‘A TIA could be a warning sign that a more severe stroke may be coming at some point in the future,’ says Dr Stander. ‘It is vital to get immediate medical attention in order to reduce your chances of having another TIA and to help prevent a more serious stroke.’
In some instances, despite testing, the cause of a stroke cannot be determined. In this case, a stroke of unknown cause is called a cryptogenic stroke.
As Dr Stander, explains, Mediclinic hospitals are being primed to offer an acute integrated stroke service led by a team of multi-disciplinary healthcare professionals to ensure the best possible results.
During September, National Heart and Stroke Awareness Month, visit a participating Mediclinic for free blood pressure and cholesterol screenings. Find your nearest screening centre here.