Types of Stroke
What are the different types of stroke?
Strokes are either:
Ischemic. These are strokes caused by blockage
of an artery (or rarely, a vein). Most strokes are this type.
Hemorrhagic. These are strokes caused by
bleeding. About 13 in 100 strokes are this type.
What is an ischemic stroke?
An ischemic stroke occurs when a
blood vessel that supplies the brain becomes blocked. This affects blood flow to part of
the brain. The brain cells and tissues start to die within minutes from lack of oxygen
and nutrients. Ischemic strokes are further divided into 2 groups:
Thrombotic strokes. These are caused by a blood clot that develops in the blood vessels inside the brain.
Embolic strokes. These are
caused by a blood clot that develops elsewhere in the body. The clot then travels
to one of the blood vessels in the brain through the bloodstream.
Thrombotic strokes are strokes
caused by a blood clot (thrombus) that develops in the arteries supplying blood to
the brain. This type of stroke is usually seen in older people, especially those with
high cholesterol and a buildup of fat and lipids inside the walls of blood vessels
(atherosclerosis) or diabetes.
Sometimes, symptoms of a
thrombotic stroke can occur suddenly. They can happen during sleep or in the early
morning. At other times, it may occur gradually over a period of hours or even
Mini-strokes are also called
transient ischemic attacks (TIAs) One of more of these may happen before a thrombotic
stroke. TIAs may last for a few minutes or up to 24 hours. They are often a warning
sign that a stroke may occur. Symptoms of a TIA are often mild and temporary, but
they are similar to those caused by a stroke.
Another type of stroke that occurs in the small blood vessels in the brain is called a lacunar infarct. The word lacunar comes from the Latin word meaning “hole” or “cavity.” Lacunar infarctions are often found in people who have diabetes or high blood pressure.
Embolic strokes are usually
caused by a blood clot that forms elsewhere in the body (embolus) and travels through
the bloodstream to the brain. Embolic strokes are often caused by heart disease or
heart surgery. They happen quickly and without any warning signs. About 3 in 20
embolic strokes occur in people with atrial fibrillation. This is a type of heart
rhythm problem where the upper chambers of the heart (atria) don’t beat well.
What is a hemorrhagic stroke?
Hemorrhagic strokes occur when a
blood vessel that supplies the brain ruptures and bleeds. When an artery bleeds into the
brain, brain cells and tissues don’t get oxygen and nutrients. Pressure also builds up
in surrounding tissues and irritation and swelling occurs. This can lead to more brain
damage. Hemorrhagic strokes are divided into 2 main categories:
Intracerebral hemorrhage. Bleeding is from the blood vessels within the brain.
Bleeding is in the space between the brain and the membranes that cover the brain
Intracerebral hemorrhage is
usually caused by high blood pressure. Bleeding occurs quickly. There are usually no
warning signs. Bleeding can be severe enough to cause coma or death.
Subarachnoid hemorrhage results
when bleeding occurs between the brain and the membrane that covers the brain
(meninges) in the subarachnoid space. This type of hemorrhage is often because of an
aneurysm or an arteriovenous malformation (AVM). It can also be caused by trauma.
An aneurysm is a weakened,
ballooned area on an artery wall. It may break (rupture). Aneurysms may be
present at birth (congenital). Or they may develop later in life because of
high blood pressure or blood vessel disease (atherosclerosis).
An AVM is a congenital
problem that has a disorderly tangled web of arteries and veins. The cause of
AVM is unknown. It’s sometimes genetic or part of certain syndromes.
What are recurrent strokes?
Recurrent strokes occur in about 1
in 4 people who have had a stroke. They happen within 5 years after a first stroke. The
risk is greatest right after a stroke and decreases over time. The likelihood of severe
disability and death increases with each recurrent stroke. About 3 in 100 people who
have had a stroke have a second stroke within 30 days of their first stroke. About
one-third have a second stroke within 2 years.