Many people recognise that a stroke is a medical emergency that can lead to permanent changes in both body and brain function, but what actually happens and what can you do to reduce your risk? It is estimated that around 80% of strokes are preventable, hence being aware of the modifiable risk factors is important.
Let’s start with understanding what a stroke is. Before we go into this, let’s consider the requirements of the brain to fully understand the impacts a stroke can have in a short period of time. Every minute, around 15-20% of the blood pumped out from the heart is directed to the brain to maintain its function. This is a large amount given the brain accounts for roughly 2% of our bodyweight! The high energy needs of the brain reflect the high and ongoing activity levels of the brain. Even when we are not actively engaging the brain, there is alot of spontaneous ongoing brain activity occuring in the background.
A stroke is the name given to an event that causes a disruption to normal blood flow in the brain. The main events that can cause this are either a blockage which is called an ischemic stroke, which is the most common event accounting for 80+% of strokes. These can happen when clot forms in the brain, when a clot from elsewhere in the body travels to the brain, or when there is a blockage of the small blood vessels within the brain.
The other event that can cause a stroke is through a brain bleed which is called a hemorrhagic stroke. This can occur when a blood vessel tears, which can be within the brain itself or in the space between the brain and it’s outer covering – this is called the subarachnoid space. Both situations cause increased pressure on the surrounding brain tissue as well as reductions in blood supply to the affected tissues. The bleeding usually increases for 3+ hours and as a result symptoms can progress over time as the pressure increases.
A disruption to blood supply to the brain for 4 minutes or more can result in permanent damage to the brain cells. In some situations, death can occur as soon as 4-6 minutes later. As a result, early intervention is critical for the best health outcomes. The after effects of a stroke are very dependant on the area of the brain that is affected as functions such as speech, movement, balance, and memory all occur in dedicated areas of the brain.
The acute symptoms of a stroke that you should look for are as follows;
- Facial change. Ask the person to smile and look for one side of the face and mouth to droop compared to the other.
- Arm weakness. Ask the person to raise both arms to shoulder height and look for a difference in the height that they lift each arm.
- Speech changes. Assess if the person’s speech is slurred or if they appear confused by asking them to repeat a simple sentence.
Other symptoms can include sudden balance loss, a headache, nausea and vomiting. If any of the above symptoms are present, it is very important to call an ambulance as soon as possible and monitor the person for any changes in their level of consciousness.
The good news is that there are many modifiable risk factors. There are online risk assessment tools such as THIS that you can use to determine your own risk. The main modifiable risk factors as are follows:
- High blood pressure. High and uncontrolled blood pressure can lead to damage to the blood vessels over time and is the strongest risk factor for hemorrhagic stroke.
- High blood sugar levels. Over time, high uncontrolled blood sugar levels can lead to the development of fatty deposits in the blood vessel walls as well as clot development.
- High cholesterol levels. High levels of LDL or “bad cholesterol” can accumulate in the blood vessels causing a narrowing of the vessels and can also lead to clot formation.
- Inactivity. Inactivity is linked with an increased risk of high blood pressure, a greater likelihood of developing type 2 diabetes and higher levels of cholesterol.
- Smoking. Smokers have twice the risk of having a stroke when compared to non smokers. Smoking can cause damage to the blood vessel walls and increases the risk of clotting. It is also linked to high blood pressure.
- Alcohol intake. Alcohol is a risk factor for high blood pressure and cardiovascular conditions such as atrial fibrillation which increase the risk of stroke. It also increases a persons risk of developing type 2 diabetes.