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Lack of Stroke Awareness Prevents Adequate Treatment
March 9, 2004 - Stroke victims, who need medical
care within three hours of the attack, are not getting to the hospital
in time for life-saving treatment, because there is so little
understanding of strokes and their symptoms.
A widespread lack of public awareness about stroke
prevents the delivery of leading-edge therapies and hampers the efforts
of researchers to test the next generation of clot-busting drugs, said
Dr. Hal Unwin, associate professor of neurology at UT Southwestern
Medical Center at Dallas.
Last year at Parkland Memorial Hospital the
primary adult teaching hospital for UT Southwestern faculty physicians
only 19 percent of 349 patients diagnosed with the most common form of
stroke arrived within three hours of the initial attack, Dr. Unwin said.
Three hours is the crucial window of time in which the fast-acting,
clot-busting drug called tissue plasminogen activator (tPA) must be
administered. The drug dissolves blood clots in the brain, greatly
reducing the risk of death or severe disability.
In June 2003 UT Southwestern launched a trial of
Desmoteplase, a second-generation clot-buster made from the saliva of
vampire bats that can be administered up to nine hours after the onset
of a stroke. But only 16 percent of 252 stroke patients screened for the
study since its inception arrived within nine hours of the onset of
stroke, and of those 40 patients, none qualified for the treatment. Some
arrived in time to receive tPA, and others failed to qualify because
they had high blood pressure, were over 85, or had taken an
anticoagulant.
Here we have this opportunity to triple the window
of time in which we can treat patients with an effective, fast-acting
drug, and we havent been able to use it in this study largely because
people dont know the signs of stroke, and they dont treat it like an
emergency, Dr. Unwin said. Its amazing the number of people we
encounter who suddenly cant use their arm one night, and theyll just
go to bed and hope its better by morning.
Stroke is the third-leading cause of death and a
leading cause of severe disability in the United States. It affects
750,000 Americans of all ages each year. Less than 3 percent of stroke
patients nationwide receive tPA, which was refined by UT Southwestern
researchers in the 1980s.
According to the American Stroke Association, 74
percent of Americans do not know the most common warning signs of
stroke:
* Sudden numbness in the arm, leg or face on one or both sides of the
body
* Unexpected severe headache with no apparent cause
* Sudden confusion, trouble speaking or comprehending
* Sudden vision problems, dizziness, and loss of balance or coordination
While stroke is more common in those over 50, it
can happen at any age, even in children. Recognition of stroke in
children has increased in recent years partly because of the widespread
use of noninvasive diagnostic tests such as magnetic resonance imaging
(MRI), computed tomography (CT), magnetic resonance angiography (MRA),
and, in the neonatal months, cranial ultrasound studies.
In children, strokes occur most frequently during
the first year of life, according to the National Institute of
Neurological Disorders and Stroke. The most common cause of stroke in
children is congenital heart disease.
Stroke is still, in many environments, poorly
understood and poorly treated. It really is a tragedy, and it strongly
emphasizes the importance of the educational process, said Dr. Duke
Samson, chairman of neurological surgery at UT Southwestern.
UT Southwestern neurologists are on call 24 hours a
day to treat stroke, either at Parkland, St. Paul University Hospital or
Childrens Medical Center Dallas. The medical center is involved in
ongoing stroke studies and is equipped with an array of high-tech tests
that help to pinpoint the cause of stroke, and, in many cases, prevent
future attacks. One such procedure preempts the chance of stroke from a
ruptured aneurysm using a medical device smaller than a standard paper
clip.
A stroke is caused when a blood vessel leading to
the brain is blocked or bursts. About 83 percent of strokes are caused
by blocked blood vessels and are called ischemic strokes. The remaining
17 percent are known as hemorrhagic strokes caused by a ruptured blood
vessel.
When either form of stroke occurs, part of the
brain begins to die from lack of oxygen and nutrients, and the parts of
the body controlled by that area of the brain are adversely affected.
Desmoteplase, the second-generation clot-buster
currently undergoing clinical trials, was discovered after Mexican
scientists hypothesized in the 1960s that bats must possess something
that keeps blood from clotting when they extract it from prey. The
specific protein responsible for the anti-clotting action was identified
in the 1980s.
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