Learn about Stroke
What is Stroke?
A stroke occurs when blood supply to part of the brain is interrupted. This event results in brain damage. Functions which are normally controlled by the damaged brain become affected suddenly and will not function properly. A stroke is a potentially life-threatening disease. Therefore, to seek early treatment is important.
There are two types of stroke: bleeding (haemorrhagic) and blockage (ischemic/infarct).
Blockage (Ischemic)
An ischemic stroke is the more common form of stroke. It occurs when an artery supplying blood to a part of the brain is blocked. The blockage is due to a blood clot being formed within an artery (thrombotic stroke) or a blood clot that travels to the brain from the heart or another artery supplying the brain (embolic stroke).
The blood clot that forms within an artery usually does so at places that have underlying atherosclerosis
How does atherosclerosis take place?
Fig. 1
Fig. 1 shows an artery with smooth endothelium (inner part of the artery wall) damaged or torn.
Fig. 2
When the endothelium layer is damaged or torn, cholesterol would be able to deposit itself into the core of the artery. Platelets would stick to the surface of the damaged tissue. Fig. 2 shows the development of the process.
Fig. 3
Over a period of time, the lumen of the artery will get narrower and results in less blood flow through it. A blood clot (thrombus) could then develop, further narrowing or completely blocking blood flow through the artery, causing a stroke.
How does a blood clot travel to the brain and cause stroke to happen?
A blood clot that travels from the heart or from an area of atherosclerosis through the artery to the brain is called an embolus. When an embolus reaches a part of the brain artery that it is not able to pass through, it will block the artery and stroke occurs.
Atrial fibrillation (irregular heart beat) can cause blood clots to be formed within the heart, which can then embolise.
Another form of stroke is haemorrhagic (bleeding).
Bleeding (Haemorrhaigc)
A haemorrhagic stroke occurs when an artery bursts within the brain, causing an intracerebral hemorrhage. Less commonly, it bursts into the space around the brain, causing a subarachnoid hemorrhage. The main causes are uncontrolled or severe hypertension (high blood pressure), structural problems with the blood vessels of the brain like aneurysm and arteriovenous malformation (AVM).
How do I know that I have a stroke?
It is important to be able to recognize the signs of stroke. The FAST test is an easy way to recognize and remember the most common signs of stroke.
FAST stands for:
Facial weakness - Can the person smile? Is his/her eye or mouth drooping?
Arm weakness - Can the person raise both arms?
Speech difficulty - Can the person speak clearly and understand what you say?
Time to act fast - Call 995 immediately
Other symptoms are difficulty in swallowing, dizziness, severe headache(“worst headache ever had”), confusion, numbness.
What are the risk factors for stroke?
Controllable risk factors:
- - Hypertension (high blood pressure)
- - Diabetes Mellitus (high blood sugar)
- - High cholesterol level
- - Smoking
- - Heart disease (eg. Atrial fibrillation, ischemic heart disease)
Uncontrollable risk factors:
- - Family history
- - Age
- - Race
