Stroke

Stroke

Preventing A Stroke

More than 2,400 years ago the father of medicine, Hippocrates, recognized and
described stroke-the sudden onset of paralysis. Until recently, modern medicine
has had very little power over this disease, but the world of stroke medicine is
changing and new and better therapies are being developed every day. Today, some
people who have a stroke can walk away from the attack with no or few
disabilities if they are treated promptly. Doctors can finally offer
stroke patients and their families the one thing that until now has been so hard
to give: hope.

In ancient times stroke was called apoplexy,* a general
term that physicians applied to anyone suddenly struck down with paralysis.
Because many conditions can lead to sudden paralysis, the term apoplexy did not
indicate a specific diagnosis or cause. Physicians knew very little about the
cause of stroke and the only established therapy was to feed and care for the
patient until the attack ran its course.

The first person to investigate the pathological signs of apoplexy was Johann
Jacob Wepfer. Born in Schaffhausen, Switzerland, in 1620, Wepfer studied
medicine and was the first to identify postmortem signs of bleeding in the
brains of patients who died of apoplexy. From autopsy studies he gained
knowledge of the carotid and vertebral arteries that supply the
brain with blood. He also was the first person to suggest that apoplexy, in
addition to being caused by bleeding in the brain, could be caused by a blockage
of one of the main arteries supplying blood to the brain; thus stroke became
known as a cerebrovascular disease (“cerebro” refers to a part of the
brain; “vascular” refers to the blood vessels and arteries).

Medical science would eventually confirm Wepfer’s hypotheses, but until very
recently doctors could offer little in the area of therapy. Over the last two
decades basic and clinical investigators, many of them sponsored and funded in
part by the National Institute of Neurological Disorders and Stroke (NINDS),
have learned a great deal about stroke. They have identified major risk factors
for the disease and have developed surgical techniques and drug treatments for
the prevention of stroke. But perhaps the most exciting new development in the
field of stroke research is the recent approval of a drug treatment that can
reverse the course of stroke if given during the first few hours after the onset
of symptoms.

Studies with animals have shown that brain injury occurs within minutes of a
stroke and can become irreversible within as little as an hour. In humans, brain
damage begins from the moment the stroke starts and often continues for days
afterward. Scientists now know that there is a very short window of opportunity
for treatment of the most common form of stroke. Because of these and other
advances in the field of cerebrovascular disease stroke patients now have a
chance for survival and recovery.

*Terms in Italics are
defined in the glossary.

 

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Cost of Stroke to the United States

  • total cost of stroke to the United States: estimated at about $43 billion /
    year
  • direct costs for medical care and therapy: estimated at about $28 billion /
    year
  • indirect costs from lost productivity and other factors: estimated at about
    $15 million / year
  • average cost of care for a patient up to 90 days after a stroke: $15,000*
  • for 10% of patients, cost of care for the first 90 days after a stroke:
    $35,000*
  • percentage of direct cost of care for the first 90 days*:

initial hospitalization = 43%
rehabilitation = 16%
physician costs =
14%
hospital readmission = 14%
medications and other expenses = 13%

* From “The Stroke/Brain Attack
Reporter’s Handbook,” National Stroke Association, Englewood, CO,
1997

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What is
Stroke?

A stroke occurs when the blood supply to part of the brain is suddenly
interrupted or when a blood vessel in the brain bursts, spilling blood into the
spaces surrounding brain cells. In the same way that a person suffering a loss
of blood flow to the heart is said to be having a heart attack, a person with a
loss of blood flow to the brain or sudden bleeding in the brain can be said to
be having a “brain attack.”

Brain cells die when they no longer receive oxygen and nutrients from the
blood or when they are damaged by sudden bleeding into or around the brain.
Ischemia is the term used to describe the loss of oxygen and nutrients
for brain cells when there is inadequate blood flow. Ischemia ultimately leads
to infarction, the death of brain cells which are eventually replaced by
a fluid-filled cavity (or infarct) in the injured brain.

When blood flow to the brain is interrupted, some brain cells die
immediately, while others remain at risk for death. These damaged cells make up
the ischemic penumbra and can linger in a compromised state for
several hours. With timely treatment these cells can be saved. The ischemic
penumbra is discussed in more detail in the Appendix.

Even though a stroke occurs in the unseen reaches of the brain, the symptoms
of a stroke are easy to spot. They include sudden numbness or weakness,
especially on one side of the body; sudden confusion or trouble speaking or
understanding speech; sudden trouble seeing in one or both eyes; sudden trouble
walking, dizziness, or loss of balance or coordination; or sudden severe
headache with no known cause. All of the symptoms of stroke appear
suddenly, and often there is more than one symptom at the same time.
Therefore stroke can usually be distinguished from other causes of dizziness or
headache. These symptoms may indicate that a stroke has occurred and that
medical attention is needed immediately.

There are two forms of stroke: ischemic – blockage of a blood vessel
supplying the brain, and hemorrhagic – bleeding into or around the brain.
The following sections describe these forms in detail.

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Ischemic
Stroke

 

An ischemic stroke occurs when an artery supplying the brain with blood
becomes blocked, suddenly decreasing or stopping blood flow and ultimately
causing a brain infarction. This type of stroke accounts for approximately 80
percent of all strokes. Blood clots are the most common cause of artery blockage
and brain infarction. The process of clotting is necessary and beneficial
throughout the body because it stops bleeding and allows repair of damaged areas
of arteries or veins. However, when blood clots develop in the wrong place
within an artery they can cause devastating injury by interfering with the
normal flow of blood. Problems with clotting become more frequent as people age.

Blood clots can cause ischemia and infarction in two ways. A clot that forms

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