Strokes are the second leading cause of death in the world, according to the American Stroke Association. Most strokes are caused by a blood clot, plaque buildup, or a combination of these two things and are known as ischemic strokes.
Around 87 percent of all strokes are ischemic strokes. The other type of stroke, known as a hemorrhagic stroke, happens when a blood vessel in or around the brain becomes weak and ruptures.
What causes an ischemic stroke?
A buildup of fat or plaque in a blood vessel can prevent blood from getting to the vital organs.
An ischemic stroke occurs as the result of atherosclerosis, which is a condition where fatty deposits or plaque build up in the body's blood vessels.
When enough plaque collects in one spot, it can prevent blood from getting through to vital organs.
Sometimes, a blood clot may be moving through the blood vessels and stick to a plaque buildup, which also creates a blockage.
The neck contains arteries known as carotid arteries that supply blood to the brain. If one of the carotid arteries becomes blocked with plaque, this can result in a stroke.
When the carotid arteries contain plaque buildup, this is known as carotid artery disease and is a major risk factor for stroke.
Atherosclerosis can occur in other arteries, such as those that lead to the heart. These are known as coronary arteries. If a blockage occurs in a coronary artery, a heart attack may occur.
Atherosclerosis does not have any symptoms, so many people do not know they have it until they have a stroke or heart attack.
The major risk factors for an ischemic stroke and carotid artery disease are the same. They include:
- High blood pressure: High blood pressure is the primary cause of stroke.
- Diabetes: People with diabetes are four times more likely to have carotid artery disease.
- Atherosclerosis or carotid artery disease, or a family history of these conditions.
- Atrial fibrillation (Afib): 15 percent of embolic strokes happen to people who have Afib.
- Cholesterol levels: This can include a high "bad" LDL cholesterol or low "good" HDL cholesterol.
- Inactivity: Not exercising can lead to high blood pressure, high cholesterol, and being overweight, which makes a person more likely to have plaque buildup in the arteries.
- Being overweight or obese.
- An unhealthful diet: Eating too many foods with saturated or trans fat, cholesterol, sodium, and sugar can lead to diabetes, plaque buildup, high blood pressure, and high cholesterol.
- Being over age 55: The risk of stroke increases after age 55 and gets greater with each additional decade of life.
Symptoms of a TIA are the same as an ischemic stroke, but they usually last less than 5 minutes and do not cause permanent damage. About a third of people who have a TIA will have a more severe stroke within 1 year.
Smoking can increase plaque buildup in the blood vessels, make blood more likely to clot, cause unhealthy cholesterol levels, make blood vessels more narrow, and damage the blood vessel lining. All of these factors also put someone at higher risk of a stroke.
Types of ischemic stroke
All ischemic strokes are caused by an interruption of blood supply to the brain. But, ischemic strokes can start in different areas of the body and may be caused by various types of blockages:
- An embolic stroke occurs when an embolus, which is a blood clot, a piece of plaque, or another object, forms somewhere else in the body and travels to the brain's blood vessels.
- A thrombotic stroke occurs when a thrombus or clot forms inside one of the blood vessels inside the brain.
Emergency medical care should be sought immediately if someone suspects a stroke.
Strokes can be very dangerous, so it is important to seek medical care immediately if warning signs appear.
Ischemic stroke symptoms often affect just one side of the body and develop quickly.
The American Stroke Association recommend that people remember F.A.S.T. This stands for:
F = Face drooping, especially one side of the face drooping or feeling numb. People can check for this by asking the person to smile or stick out their tongue; if their smile is uneven or their tongue goes to one side instead of the middle, this could be a warning sign.
A = Arm weakness, being unable to lift one arm or feeling weakness or numbness in one arm.
S = Speech problems, such as being unable to speak or repeat a sentence clearly.
T = Time to call 9-1-1.
Beyond F.A.S.T., a stroke may also cause the following symptoms that come on very quickly and appear suddenly:
- being unable to move one side of the body
- trouble walking or dizziness, falling without cause
- confusion, being unable to understand speech
- vision problems or trouble seeing
- a severe headache without an apparent cause
With a stroke, every minute counts. The brain relies upon a constant supply of oxygen-rich blood, so a blockage that lasts for just a few minutes can begin to damage and kill brain cells.
If a person has signs of a stroke, someone should call 9-1-1. Treatments for ischemic stroke include:
- Medication: A clot-busting medication called tissue plasminogen activator (tPA) is given through a vein in the arm. It must be given within 4 hours from the beginning of stroke symptoms in order to work. The sooner tPA is given, the better the outcome.
- Surgery to remove the clot: After a patient receives tPA, they may undergo a procedure known as mechanical thrombectomy, which involves removing the clot with a catheter. This procedure must be done within 6 hours of symptoms.
Preventing an ischemic stroke
With a stroke, prevention is better than treatment. Even people with risk factors or a history of stroke can take steps to become more healthy.
Getting regular medical tests, including blood pressure and cholesterol checks, can help people detect problems early.
The following measures can help prevent a stroke from happening and improve overall health:
- Getting regular medical tests: High blood pressure and cholesterol do not have visible symptoms; so getting regular health tests is the only way to know if a person has them. Blood tests and health checkups can help detect these problems early so they can be treated.
- Getting regular exercise: Being active lowers the risk of diabetes, high blood pressure, high cholesterol, and other conditions linked to ischemic stroke.
- Following a heart-healthy diet: A diet should be low in "bad" fats such as saturated and trans fats and sodium. Eating more fruits, vegetables, whole grains, healthful fats, and lean protein helps keep blood vessels healthy.
- Losing weight if needed: A healthy weight lowers the risk factors for stroke.
- Avoiding smoking or being around smoke: Smoking and breathing smoke from others damages blood vessels and increases the risk of stroke-related health problems.
- Being aware of family history: Always discuss a family history of stroke or TIA with a doctor.
- Daily aspirin: A doctor may recommend that a person who has a high risk of a heart attack or stroke and a low risk of bleeding take a daily aspirin. Guidelines no longer recommend the widespread use of aspirin for this purpose, due to the high risk of bleeding.
- Getting enough sleep and managing stress: Getting 7 to 8 hours of sleep and trying to lower stress may help with stroke risk and overall health.
A stroke can be frightening and can occur in someone who seems to be otherwise healthy.
Knowing the warning signs and getting emergency medical care is the most important thing to do if a stroke is suspected.
People should not drive the affected individual to the hospital. Instead, they should call an ambulance so that paramedics can give medical care as quickly as possible. They can also take the person to the hospital that can provide the best stroke care, which is not always the closest facility.