stroke is a sudden loss of consciousness or other neurological
dysfunction caused by loss of blood flow to one or more regions
of the brain.
Like all cells in the body, brain cells
depend on blood to supply the oxygen and nutrients they need
to function. When this supply is cut off or drastically reduced,
cells downstream which depend on that supply begin to starve
and die. In the brain, this is called a stroke, or sometimes
a "brain attack".
One kind of stroke is a hemorrhagic stroke,
in which a blood vessel ruptures and bleeds or hemorrhages.
It may be caused by injury or aneurysm.
Hemorrhagic stroke accounts for about 20% of strokes, and
is usually associated with hypertension or high blood pressure.
The risk for hemorrhagic stroke in individuals with hypertension
can be reduced by treating the hypertension through healthy
diet and exercise, reducing or managing stress, limiting caffeine
and abstaining from smoking.
A second kind of stroke is an ischemic stroke, in which a
small blood clot becomes wedged in one of the tiny blood vessels
supplying the brain, blocking the flow of blood. This blood
clot may have formed in the brain, or it may have formed elsewhere,
broken free, and traveled through the blood stream to reach
the brain. The brain is particularly susceptible to such blockages
because of the high number of tiny blood vessels in which
a blood clot can lodge. Ischaemic stroke is usually associated
with arteriosclerosis ("hardening of the arteries") and accounts
for about 80% of strokes. Risk for ischaemic stroke is reduced
by the same factors that reduce arteriosclerosis -- regular
exercise, a diet low in saturated fats, no smoking - as well
as by treating any co-existing conditions such as obesity,
diabetes and hypertension.
A transient ischemic attack (TIA), often called a "mini-stroke", is a temporary interference with blood flow to the brain. The symptoms may include light-headedness, numbness, loss of balance, fleeting blindness, and problems swallowing or speaking. These symptoms persist for minutes to hours. After the attack, there may be no long-term neurological damage; since TIAs are generally painless, the person may be unaware that a stroke has occurred. TIAs may result from many causes, including decreased heart function, low blood pressure, and overmedication with drugs to treat high blood pressure. Without treatment, about 5% of people experiencing a TIA go on to develop a full-blown stroke within a year.
Stroke is the third leading cause of death
in the US. The outcome of a stroke depends on the degree and
length of time for which blood flow is reduced. About 70%
of stroke patients recover well enough to lead independent
lives, but many patients suffer permanent debilitating damage
which may include partial paralysis, problems producing and
understanding speech, and cognitive deficits. The particular
symptoms experienced depend on where the stroke occurred:
a stroke which occurs in a blood vessel which normally supplies
the part of the brain which oversees speech production can
result in deficiencies in speech production, and so on.
Article : "VASCULAR
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain
Artwork copyright © 2000 Ann L. Myers