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| | Title: | What is Stroke? | | Article: | Stroke is a disease, which affects the brain blood
vessels and interrupts the brain blood supply.
How a stroke happens?
A stroke happens when an artery, which delivers oxygen
and nutrients to the brain, either ruptures suddenly
or becomes blocked by a mass (embolus) or a blood
clot. This burst or clogging deprives the brain from
blood and oxygen. Affected nerve cells die in several
minutes. Normal nerve cells control your body. Dead
brain cells loose any control. The effect is
devastating. Dead brain cells are not replaced.
Two types of stroke include ischemic stroke (blockage
of a blood vessel) and hemorrhagic stroke (bleeding
into brain). Bleeding stroke is a much deadlier then
clot-caused stroke.
Ischemic stroke is the most common. Almost 9 out of 10
strokes are ischemic. Ischemic stroke happens when a
blood clot (thrombus) blocks blood delivery to the
brain. Blood clots usually occur in arteries damaged
by fat, calcium and cholesterol accumulation. The
buildup process has the name “atherosclerosis”.
Cerebral thrombotic stroke is the type when blood clot
forms within an artery of the brain. That often
happens at night or first thing in the morning. Very
often a transient ischemic attack (TIA) precedes this
type of stroke. Transient means that it resolves in 24
hours.
How cerebral embolism develops? A loose clot or some
other particle that moves inside blood vessels is
named an embolus. The clot usually appears far away
from the brain - in the heart or great vessels. An
embolus causes an ischemic stroke. The clot is moving
with bloodstream until it gets into a brain artery and
blocks the blood flow. Commonly it happens during
atrial fibrillation – a heart disease with irregular
heart rhythm. Atrial fibrillation affects more then 2
million people just in America alone. It's responsible
for 15–20 percent of all strokes. The clots are formed
in the heart chambers named the atria.
Hemorrhagic stroke.
When a brain blood vessel ruptures and bleeds in the
space between the brain and the skull, it is the
subarachnoid hemorrhage. When a ruptured brain artery
bursts, and blood goes into brain tissue, it is the
cerebral hemorrhage.
Hemorrhage (bleeding) in the brain happens after a
head injury or a burst of aneurysm. Aneurysm is an
abnormal pouch in the artery wall. Aneurisms often
happened when high blood pressure distends arteries.
Another type is congenital aneurysm. It is not
dangerous until it bursts and causes a hemorrhagic
stroke. Aneurysms are dangerous namely because they
may burst.
Cerebral or subarachnoid hemorrhage deprives brain
cells from blood and oxygen, but what is worse, the
lost blood from the ruptured artery compress
surrounding brain and vessels and disrupts blood
supply and brain function even more. Severe damage
results, when the pressure is high. Often people with
cerebral hemorrhages die. Yet those, who live, tend to
recover better than people with ischemic (clot)
stroke. That happens because blocking a blood vessel
cause brain cells to die in minutes, and the brain
does not recover. In contrast, when a blood vessel
bursts and pressure squeeze part of the brain, during
recovery the pressure slowly goes away and the brain
regain some of the function.
For information on stroke, call the American Stroke
Association at 1-888-4-STROKE. | | Author: | Aleksandr Kavokin, MD, PhD | | System: | Brain | | Subject: | Stroke | | Abstract: | A stroke happens when an artery, which delivers oxygen
and nutrients to the brain, either ruptures suddenly
or becomes blocked by a mass (embolus) or a blood
clot. | | Website: | http://www.kavokin.com | | Time: | 20:10 | | Reference: | http://www.rdoctor.com | | Reference 2: | http://www.sympomat.com |
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Articles by Aleksandr Kavokin, MD, PhD
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