Every two seconds, someone in the world has a stroke. One out of every six people will experience a stroke at some point in their lives.
A stroke deprives brain cells of oxygen and is one of the most common causes of death, as well as a leading cause of preventable disability. But what causes strokes in the first place? And what can doctors do to treat them?
The brain accounts for only 2% of the body’s weight but consumes more than 20% of the oxygen in the blood. Oxygen reaches the brain through an arterial system. The carotid arteries supply oxygen to the front of the brain, while the vertebral arteries supply the back.
These arteries are interconnected and branch into smaller and smaller vessels to ensure that billions of neurons receive the necessary oxygen.
If blood flow is interrupted, the oxygen supply stops, and brain cells begin to die.
This can happen in two ways:
- A hemorrhagic stroke occurs when a blood vessel ruptures, causing blood loss.
- The more common type is an ischemic stroke, where a blood clot blocks a vessel, stopping the flow of blood.
So where do these clots come from?
In rare cases, a sudden change in heart rhythm can prevent the upper chambers of the heart from contracting normally. This slows blood flow, causing platelets, clotting factors, and fibrin strands to clump together.
The clot is then transported to the arteries supplying the brain until it can no longer pass through.
This is called an embolism, which cuts off oxygen to all the cells downstream. The brain itself has no pain receptors, so you don’t feel the blockage.
However, oxygen deprivation slows brain function, which can lead to noticeable and sudden effects. For example, if the affected area controls language, speech may become slurred. If the stroke affects the part of the brain that controls muscle movement, it may cause weakness, often on just one side of the body.
How is a Stroke Treated in an Emergency?
When a stroke occurs, the body tries to compensate by rerouting blood flow to the affected area, but this is not a long-term solution.
Eventually, oxygen-starved brain cells begin to die, leading to severe and potentially permanent brain damage.
That’s why getting medical help as quickly as possible is crucial. The first treatment is typically an intravenous drug called tissue plasminogen activator (tPA), which breaks up the clot and allows blood to flow again in the blocked artery.
If administered within a few hours, this drug significantly increases the chances of survival and reduces long-term effects.
If tPA cannot be used—because the patient is on other medications, has a history of severe bleeding, or the clot is too large—doctors will perform a procedure called endovascular thrombectomy.
Using fluorescent dye to highlight the blood vessels under powerful X-rays, a doctor inserts a long, thin, flexible tube called a catheter into an artery in the leg and guides it to the blockage.
A clot retrieval device is inserted through the catheter, which expands and hooks onto the clot once it passes. The catheter is then used to pull the clot out.
These treatments must be performed as quickly as possible to preserve brain function, meaning it is essential to recognize the signs of a stroke.
How Can You Tell if Someone is Having a Stroke?
Here are three quick tests to check for signs of a stroke:
- Ask the person to smile (Face – F): A drooping mouth or facial sagging may indicate muscle weakness.
- Ask them to raise both arms (Arm – A): If one arm drifts down, the weaker arm may be a sign of a stroke.
- Ask them to repeat a simple word or phrase (Speech – S): Slurred or unusual speech may indicate oxygen deprivation in the brain’s language area.
This is often referred to as the FAST test, with T standing for Time. If you notice any of these signs, call emergency services immediately. A life could depend on it.
Watch the full video “What Happens During a Stroke?” HERE. The video is featured on TED-Ed’s YouTube channel, with nearly 25 million subscribers.