What is a stroke?
A stroke occurs when the blood supply to the brain is suddenly interrupted or when a blood vessel in the brain malfunctions. There are two types of strokes: ischemic and hemorrhagic.
Ischemic strokes occur when an artery that supplies blood to the brain becomes blocked, causing a significant or even complete disruption in blood flow, ultimately causing a blood clot in the brain. About 80 percent of all strokes are ischemic. Blood clotting is a healthy and necessary process as it helps stop bleeding and helps repair damage to arteries and blood vessels. However, when a blood clot develops in the wrong place inside an artery, the result can drastically impair blood flow and lead to a devastating stroke.
Blood clots can cause ischemic strokes in two ways. A clot that forms in a part of the body other than the brain can travel through the body’s blood vessels and become wedged inside a brain artery. The blood clot may become "stuck" to the inside of the artery wall, where it continues to grow in size, eventually becoming large enough to block blood flow. The build-up of plaque deposits on the walls inside an artery is another cause of ischemic stroke. The deposits cause a thickening and hardening of artery walls, resulting in loss of elasticity and a decline in blood flow.
Hemorrhagic stroke occurs when an artery in the brain bursts, causing a sudden drop in the brain’s blood supply. The bleeding that results from a ruptured artery can cause a dangerous increase in pressure inside the brain and lead to serious, potentially fatal brain damage. Approximately 20 percent of strokes are hemorrhagic.
There are two main causes of hemorrhagic strokes: some are caused by a weakening or thinning of part of the affected blood vessel. The presence of high blood pressure over a sustained period of time stretches and expands blood vessels, causing thinning and weakening spots to be stretched out until they burst and spill blood into the brain.
The other main cause results from plaque build-up inside artery walls. The walls eventually lose their elasticity and become thin and brittle, making them especially susceptible to rupture in patients with high blood pressure.
When blood flow to the brain is interrupted, normal brain function becomes impaired and the blockage of blood flow triggers the onset of a stroke.
The most common stroke symptoms include:
- Numbness in the arms, legs and face affecting one side of the body;
- Confusion, difficulty speaking and difficulty understanding speech;
- Impaired vision in one or both eyes;
- Unexplained dizziness or severe headache;
- Loss of balance or coordination, in some cases including loss of consciousness.
If you notice any of these symptoms, it’s safest to assume you are suffering some type of stroke that requires urgent medical attention. Stroke is a serious event that causes greater damage and is more likely to be fatal the longer it goes untreated.
There are a number of factors that influence a person’s stroke risk; most of them are so-called "lifestyle" risk factors, the result of unhealthy behaviors and poor health habits.
Hypertension (high blood pressure) is considered to be the most influential risk factor for stroke. People with hypertension are four to six times more likely to suffer a stroke compared to people with healthy (120/80) blood pressure.
Diabetes is another disease that increases the risk of suffering a stroke; diabetics are three times more likely to suffer a stroke than non-diabetics. In addition, patients with diabetes have higher rates of hypertension, high cholesterol and heart disease, each of which increases stroke risk.
High cholesterol is among the key stroke risk factors and is a leading cause of heart disease. Unhealthy levels of blood cholesterol cause fatty deposits to accumulate inside arteries and blood vessels, gradually reducing the flow of blood to the heart, brain, and throughout the body.
Smokers are more than three times as likely to suffer a stroke compared to non-smokers. That risk begins to drop very soon after a person stops smoking.
Excessive alcohol consumption is a risk factor for stroke as it reduces the body’s clotting ability and damages blood viscosity. In addition to stroke, excessive alcohol consumption is also associated with higher risk for brain hemorrhages and brain tissue damage.2
Other factors that increase the risk of stroke include lack of exercise, being overweight or obese, having a family history of stroke, and certain heart valve function disorders.
The good news is the main causes of stroke -- high blood pressure, diabetes, high cholesterol, smoking, excessive alcohol consumption, and poor diet and exercise habits -- involve lifestyle choices. That means individuals have the power to lower their personal stroke risk by making better lifestyle and health choices. Your doctor has a variety of resources available to help take the first steps to make important changes, and stick to them.
F.A.S.T. action save lives
A stroke comes quickly with little or no warning, and it doesn’t take long for the damage to become severe, even deadly. If someone near you suffers stroke-like symptoms, you can reduce the stroke’s severity and potentially save a life by taking the following F.A.S.T. action:
- Facial: Ask the person to smile in order to observe whether one side of the face doesn’t respond.
- Arms: Instruct the person to raise both arms and keep them raised for ten seconds; one arm drifting downward indicates a likely stroke.
- Speech: Have the person repeat a simple sentence to check for slurring or other speech problems.
- Time: If the person exhibits any of these problems, waste no time in getting the victim to a hospital emergency room without delay.
Act FAST at the first sign of stroke. The sooner a stroke victim receives medical attention, the better chance they have to survive a stroke with less permanent damage. Keep Bumrungrad’s emergency hotline number (0 2667 1175-76) stored in your phone.
- US National Institute of Neurological Disorders and Stroke
- Medical University of South Carolina