Stroke is one of the leading
causes of
serious permanent disability in
adults and is the third leading cause of death in the
country.
Ischemic
Ischemic strokes
is caused when the arteries to
the brain become narrowed or blocked, causing
severely reduced blood flow (ischemia).
Ischemic
strokes can be further divided into the following two
categories:
1.
Thrombotic
A thrombotic stroke
is caused when a blood clot (thrombus) forms in one of the
arteries that supply blood to the
brain. A clot may be
caused by fatty deposits (plaque) that build up in
arteries and cause reduced blood flow (atherosclerosis)
or other artery conditions.
2.
Embolic
An embolic stroke
is caused when a blood clot or other debris forms away from
the brain,
commonly in
the heart,
and is swept through the
bloodstream to lodge in narrower brain arteries. This
type of blood clot is called an embolus.
Hemorrhagic
Hemorrhagic strokes
is caused when
a blood vessel that supplies the brain ruptures and bleeds.
When an artery bleeds into the brain, brain cells and
tissues do not receive oxygen and nutrients. In addition,
pressure builds up in surrounding tissues and irritation and
swelling occur, which can lead to further brain damage.
Hemorrhagic strokes are
further divided into
the following two categories:
1.
Intracerebral
An
intracerebral stroke is caused
by hypertension (high blood pressure), and bleeding
occurs suddenly and rapidly. There are usually no
warning signs and bleeding can be severe enough to cause
coma or death.
2.
Subarachnoid
A subarachnoid
stroke is caused when bleeding occurs between the brain and the
meninges in the subarachnoid
space. This type of hemorrhage is often due to an
aneurysm or an
arteriovenous malformation (AVM).
How a person
recovers from a stroke depends on
the location of the brain involved and the extent of damage
done.
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