There are two main types of cerebrovascular accident, or stroke: an ischemic stroke is caused by a blockage; a hemorrhagic stroke is caused by the rupture of a blood vessel. Both types of stroke deprive part of the brain of blood and oxygen, causing brain cells to die.
An ischemic stroke is the most common and occurs when a blood clot blocks a blood vessel and prevents blood and oxygen from getting to a part of the brain. There are two ways that this can happen. One way is an embolic stroke, which occurs when a clot forms somewhere else in your body and gets lodged in a blood vessel in the brain. The other way is a thrombotic stroke, which occurs when the clot forms in a blood vessel within the brain.
A hemorrhagic stroke occurs when a blood vessel ruptures, or hemorrhages, and then prevents blood from getting to part of the brain. The hemorrhage may occur in any blood vessel in the brain, or it may occur in the membrane surrounding the brain.
The quicker you can get a diagnosis and treatment for a stroke, the better your prognosis will be. For this reason, it’s important to understand and recognize the symptoms of a stroke.
Stroke symptoms include:
- difficulty walking
- loss of balance and coordination
- difficulty speaking or understanding others who are speaking
- numbness or paralysis in the face, leg, or arm, most likely on just one side of the body
- blurred or darkened vision
- a sudden headache, especially when accompanied by nausea, vomiting, or dizziness
The symptoms of a stroke can vary depending on the individual and where in the brain it has happened. Symptoms usually appear suddenly, even if they’re not very severe, and they may become worse over time.
Remembering the acronym “FAST” helps people recognize the most common symptoms of stroke:
- Face: Does one side of the face droop?
- Arm: If a person holds both arms out, does one drift downward?
- Speech: Is their speech abnormal or slurred?
- Time: It’s time to call 911 and get to the hospital if any of these symptoms are present.
Each type of stroke has a different set of potential causes. Generally, however, stroke is more likely to affect a person if they:
- have overweight or obesity
- are 55 years of age or older
- have a personal or family history of stroke
- have high blood pressure
- have diabetes
- have high cholesterol
- have heart disease, carotid artery disease, or another vascular disease
- are sedentary
- consume alcohol excessively
- use illicit drugs
Some studies have found that males have a higher risk of death from stroke than females. However, one 2016 review of studiesTrusted Source suggests that these differences do not take into account adjustments for race, age, the severity of the stroke, and other risk factors.
The review explains that the risk of stroke mortality often increases due to age and demographic, rather than the biological differences between males and females.
According to a 2016 analysis Trusted Source, African American people have a significantly higher risk of experiencing a first-time stroke. They are also around 60% more likely to experience another stroke within 2 years.
The following sections describe the specific causes of each type of stroke.
This type of stroke occurs due to blockages or narrowing in the arteries that provide blood to the brain. This causes ischemia, or a severely reduced blood flow, which damages brain cells.
Blood clots often cause ischemic stroke. Clots can form in the brain arteries and other blood vessels in the body. The bloodstream carries these into narrower arteries in the brain.
Fatty plaque deposits within the arteries can also cause clots that result in ischemia.
Leaky or burst arteries in the brain can give rise to hemorrhagic strokes.
Leaked blood puts pressure on brain cells and damages them. It also reduces the blood supply that can reach the brain tissue after the hemorrhage.
Blood vessels can burst and spill blood into the brain or near the surface of the brain. This may also send blood into the space between the brain and the skull.
Having hypertension, experiencing physical trauma, taking blood-thin
ning medications, and having an aneurysm can all make a blood vessel leak or burst.
Intracerebral hemorrhage is the most common type of hemorrhagic stroke. This occurs when brain tissue floods with blood after an artery bursts.
Subarachnoid hemorrhage is another type of hemorrhagic stroke. These are less common. In a subarachnoid hemorrhage, bleeding occurs in the area between the brain and the thin tissues that cover it.
TIAs only briefly interrupt the flow of blood to the brain. They are similar to ischemic strokes, in that they occur due to clots.
People should treat them as medical emergencies, even if the symptoms are temporary. They serve as warning signs for future strokes and indicate a partially blocked artery or clot source in the heart.
According to the Centers for Disease Control and Prevention (CDC)Trusted Source, over a third of people who experience a TIA have a major stroke within a year if they do not receive any treatment. Around 10–15% of people will have a major stroke within 3 months of experiencing a TIA.