Definition of Stroke
Stroke: The sudden death of some brain cells due to a lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain. A stroke is also called a cerebrovascular accident or, for short, a CVA.
Symptoms of a stroke depend on the area of the brain
affected. The most common symptom is weakness or paralysis of
one side of the body with partial or complete loss of voluntary
movement or sensation in a leg or arm. There can be speech problems
and weak face muscles, causing drooling. Numbness or tingling
is very common. A stroke involving the base of the brain can affect
balance, vision, swallowing, breathing and even unconsciousness.
A stroke is a medical emergency. Anyone suspected
of having a stroke should be taken immediately to a medical facility
for diagnosis and treatment.
The causes of stroke: An artery to the brain may be blocked
by a clot (thrombosis) which typically occurs in a blood vessel that
has previously been narrowed due to atherosclerosis ("hardening of
the artery"). When a blood clot or a piece of an atherosclerotic
plaque (a cholesterol and calcium deposit on the wall of the artery)
breaks loose, it can travel through the circulation and lodge in an
artery of the brain, plugging it up and stopping the flow of blood;
this is referred to as an embolic stroke. A blood clot can form in a
chamber of the heart when the heart beats irregularly, as in atrial
fibrillation; such clots usually stay attached to the inner lining of
the heart but they may break off, travel through the blood stream,
form a plug (embolism) in a brain artery to cause a stroke. A
cerebral hemorrhage (bleeding in the brain), as from an aneurysm
(a widening and weakening) of a blood vessel in the brain, also
causes stroke.
The diagnosis of stroke involves a medical history and a
physical examination. Tests are done to search for treatable causes
of a stroke and help prevent further brain damage. A CAT scan (a
special X-ray study) of the brain is often done to show bleeding into
the brain; this is treated differently than a stroke caused by lack
of blood supply. A CAT scan also can rule out some other conditions
that may mimic a stroke. A soundwave of the heart (echocardiogram)
may be done to look for a source of blood clots in the heart.
Narrowing of the carotid artery (the main artery that supplies blood
to each side of the brain) in the neck can be seen with a soundwave
test called a carotid ultrasound. Blood tests are done to look for
signs of inflammation which can suggest inflamed arteries. Certain
blood proteins are tested that can increase the chance of stroke by
thickening the blood.
Stroke look-alikes: Just because a person has slurred speech
or weakness on one side of the body does not necessarily mean that
person has had a stroke. There are many other nervous system disorders
that can mimic a stroke including a brain tumor, a subdural
hematoma (a collection of blood between the brain and the skull) or a
brain abscess (a pool of pus in the brain caused by bacteria or
a fungus). Virus in the brain (viral encephalitis) can cause symptoms similar to those of
a stroke, as can an overdose of certain medications. Dehydration or
an imbalance of sodium, calcium, or glucose can cause neurologic
abnormalities similar to a stroke.
Treatment of a stroke: Early use of anticoagulants to
minimize blood clotting has value in some patients. Treatment of
blood pressure that is too high or too low may be necessary.
(Lowering elevated blood pressure into the normal range is
no longer recommended during the first few days following a stroke
since this may further reduce blood flow through narrowed arteries
and make the stroke worse.) The blood sugar glucose in diabetics is
often quite high after a stroke; controlling the glucose level may
minimize the size of a stroke. Drugs that can dissolve blood clots
may be useful in stroke treatment. Oxygen is given as needed. New
medications that can help oxygen-starved brain cells survive while
circulation is reestablished are being developed.
Rehabilitation: When a patient is no longer acutely ill
after a stroke, the aim turns to maximizing the patient's
functional abilities. This can be done in an inpatient rehabilitation
hospital or in a special area of a general hospital and in a nursing
facility. The rehabilitation process can involve speech therapy to
relearn talking and swallowing, occupational therapy for regaining
dexterity of the arms and hands, physical therapy for improving
strength and walking, etc. The goal is for the patient to resume as
many of their pre-stroke activities as possible.
Footnote: The term "stroke" reflects the belief among the
ancient Greeks and Romans that someone suffering a stroke (or any
sudden incapacity) had been struck down by the gods.
Last Editorial Review: 7/4/1999 2:40:00 PM
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