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Stroke
(Brain Attack):
Intra-arterial
Thrombolysis for Treatment of Patients with Acute Cerebrovascular Infarction
Every year, more than 500,000 individuals suffer strokes. Strokes usually
occur suddenly, with very little or no warning, and their effects can be
severe, even fatal. Strokes are the leading cause of functional disability
in the United States. They are the third leading cause of death. Yet much of
the American public remains uninformed about stroke. A recent Gallup survey
of adults 50 years and over showed that 97% could not name “stroke warning”
signs.
There are, however, several factors known to contribute to a higher risk of
stroke, as well as symptoms to indicate that you are on course to suffer a
stroke. Knowing these risk factors and symptoms can help to decrease your
chances of having a stroke. If you experience a stroke, understanding that
treatment options are available can increase your chances for a full and
rapid recovery.
Now emphasis must be placed on early detection. Hospital staff and emergency
medical personnel must learn how to recognize the signs and symptoms of
stroke so that thrombolytic therapy can be initiated as early as possible.
Public awareness of the signs and symptoms of stroke must be increased so
patients will seek medical attention earlier. Patient education about stroke
warning signs and symptoms will pay big dividends for those unlucky enough
to have a stroke. At present, only about 5% of stroke victims meet the
criteria for thrombolytic therapy, and too-late presentation is the most
common reason for disqualification. The Copenhagen Stroke Study reported
that only 25% of 1,200 patients with acute stroke were admitted to the
hospital within 3.5 hours of stroke onset (and only 68% within 24 hours).
Consider providing a flyer of stroke warning signs and symptoms for patients
at high risk. Stress the minor symptoms. In Copenhagen, the occurrence of
less severe stroke manifestations was one of the two most important
predictors of delay in presentation. The other was not having someone else
around to notice the event.
More than 300 reports of the use of thrombolytic agents in the treatment of
stroke have been published in the past 10 years. Since 1990, studies of
thrombolytic therapy can be broken down into two large categories:
symptom-based trials and angiography-based trials. Symptom-based trials use
intravenous agents and consider only clinical outcome, while
angiography-based trials use intravenous or intra-arterial agents and
correlate clinical outcome with reperfusion of cerebral arteries.
At GHS, to create awareness of new, more aggressive stroke treatments, the
neurovascular section (a multidisciplinary team of clinicians interested in
improving the care of patients with neurovascular disorders) is helping to
promote the Brain Attack Program. As the name suggests, the program
emphasizes the importance of treating stroke as a medical emergency, much
like treatment for a heart attack.
New stroke therapies available at GHS require rapid and accurate diagnosis
of the cause of stroke and the location of its origin in the brain. The
program involves stroke prevention and treatment using drugs available at
most academic health centers throughout the country. These treatments must
be initiated within six hours of the onset of stroke symptoms. They are
cooperative efforts among Departments of Emergency Medicine, Neurology,
Neurosurgery, Diagnostic Radiology and pre-hospital care providers.
Stroke causes
Stroke occurs when too little blood flows to the brain. Cells in that area
of the brain die, and the part of the body they control cannot function. The
earlier that medical intervention is started after the onset of symptoms,
the greater the probability of limiting or reversing brain damage.
Regular blood flow to the brain can be interrupted in various ways. One way
is when a fatty deposit, or thrombus, forms in the bloodstream and blocks,
or plugs, a blood vessel. This is a process called thrombosis, or a
thrombotic stroke. Another way blood flow is interrupted is when a thrombus
detaches itself from the original site and passes through the bloodstream
until it blocks a smaller vessel. This is called embolization, or an embolic
stroke. In contrast, when a blood vessel ruptures, it is called a
hemorrhagic stroke.
Stroke symptoms
Most symptoms of a stroke occur suddenly but can vary in their range of
severity. The following symptoms, alone or in combination with one another,
may indicate you are about to experience a stroke:
Paralysis or weakness on one side of the face or in the arm or leg on one
side of the body
Abnormal or slurred speech or difficulty understanding speech
Numbness or loss of sensory impulses on one side of the face or in the arm
or leg of one side of the body
Headaches, usually severe or abrupt
Vision loss, or blurred or decreased vision in one or both eyes
Balance and coordination problems
The goal of thrombolytic therapy is to reestablish blood flow prior to
tissue death. But if the blood supply is restored after too much damage has
occurred, the patient will suffer a dangerous hemorrhage in the brain. The
faster blood flow is restored, the less brain tissue will be damaged.
No matter how compelling the picture that emerges from the history and
physical examination, ask yourself one more time: Is it really a stroke? The
mimics are many, and most of these mimics can easily be excluded by asking
the correct questions in the history and ordering the appropriate tests. The
rush of events cannot distract one from considering all the possibilities,
for no one should give a beneficial but potentially lethal drug or therapy
to a patient who does not have the target disease process the drug or
therapy is designed to treat.
Diagnostic Studies
CT is the study in suspected acute stroke. CT is valuable for ruling out
some mimics of stroke. It can identify subdural hematoma in an elderly
patient who presents with seizures or focal deficits that resemble ischemic
stroke. It clearly differentiates brain tumors, subdural hematomas, or
abscesses that can also manifest similarly to strokes.
CT angiography (CTA) can be done on all patients with acute stroke <6 hours
in duration at GMH. CTA has high sensitivity and specificity to evaluating
thrombi in the major intracranial vessels: M1 (main stem) segment of the
middle cerebral artery, distal internal carotid artery, or basilar artery.
CTA can provide information quickly and safely regarding which patients
should go on to angiography for potential intra-arterial thrombolysis. IA
thrombolysis is used primarily to treat thrombus in the proximal
aforementioned intracranial vessels, and the trials to date have focused on
catheter-directed intervention in these vessels primarily. If the CTA shows
the M1 segment of the middle cerebral artery, distal internal carotid
artery, or basilar artery to be normal without thromboembolism, studies have
shown they will be normal on angiography, and thereby no catheter-directed
IA thrombolysis would need to be performed. Therefore, CTA will help prevent
un-necessary angiography from being performed.
Choosing the Right Therapy
The current therapeutic options for acute ischemic stroke include
thrombolytic medication to dissolve clots and reestablish blood flow,
anticoagulants to inhibit thromboembolism formation, and surgery. Acute
recourse in some hemorrhagic strokes consists mainly of surgery to evacuate
a hematoma or clip an aneurysm, together with eliminating contributing
factors such as high blood pressure or anticoagulant drugs.
Before proceeding with therapy, weigh the hoped-for results against the
quality of life it is expected to preserve and the patient's (or family's)
stated attitudes toward living with disabilities.
Thrombolytic Therapy
The principal advantage of the intravenous route is the rapidity with which
it can be delivered; it seems clear that thrombolytic therapy is safest when
it can be delivered promptly after the onset of ischemia. Intra-arterial
delivery provides far better diagnostic precision, and this therapy is much
more effective in clearing intra-arterial clots.
Thrombolysis is not suitable when a patient's general level of health is so
poor that he or she is not likely to live long enough to benefit from
treatment.
Intravenous thrombolysis
This treatment involves a clot-busting medication that is given
intravenously. Under certain circumstances and, if given rapidly (<3hours)
after a stroke, studies have shown it to be beneficial to patients and may
prevent further damage. This may be given alone or in combination with
intra-arterial thrombolysis.
Intra-arterial thrombolysis
The procedure - similar to catheterization of the heart - uses advances in
catheter technology, including the development of tiny microcatheters. This
treatment must be performed within six hours of the onset of symptoms. The
microcatheter is placed into the blood vessel containing the clot and used
to deliver thrombolytics and mechanically disrupt the clot. This often opens
the blood vessel effectively and can lead to complete recovery. Prospective,
multi-institutional, randomized controlled trials (PROACT II) have shown
that patients treated with IA r-ProUK (a thrombolytic drug) will receive a
60% relative benefit, and a 15% absolute benefit, with no increase in
mortality. This study has prompted the American Society of Interventional
and Therapeutic Neuroradiology to release the following statement:
Prior to PROACT II trial results, it had been the consensus opinion of the
American Society of Interventional and Therapeutic Neuroradiology (ASITN)
and the Society of Cardiovascular & Interventional Radiology (SCVIR) that
intra-arterial thrombolytic therapy for acute stroke was investigational.
Although the results of the trial did not lead to FDA approval of a specific
drug, the results of this trial are convincing evidence that intra-arterial
thrombolytic therapy can now be considered an acceptable and appropriate
therapy for acute stroke.
Issues in Follow-Up
Stroke is a highly dynamic medical crisis. The clinical picture on day one
may evolve into something very different on day two. Some ischemic strokes
generate unfortunate hemorrhagic complications. Or, ischemia may expand
beyond all reasonable expectation.
We have devised a set of absolute and relative contraindications which
guides our decision making process, which are available in the Emergency
Department.
The most feared complication of thrombolytic therapy is hemorrhage,
especially intracerebral hemorrhage. In deciding about thrombolytic therapy,
we make a decision based on the presumed mechanism of disease, the duration
of the ischemia, and the subsequent risk of hemorrhage. After catheter
directed local intra-arterial thrombolysis, patients are admitted to the
intensive care unit, to be absolutely certain that oxygenation and systemic
blood pressure are maintained and that fever is prevented. This setting is
also important for close clinical monitoring of patients anticoagulated
after angiography and/or thrombolysis, to help prevent bleeding
complications or, at the opposite extreme, re-thrombosis.
As we move into a new era of treatment for stoke, it is important that we
proceed with both enthusiasm and caution. We must ensure that mechanisms are
in place so that clinical trials can be carried out in a safe and scientific
manner, providing data that yield valid conclusions. At GHS, the
neuroradiologists are committed to providing this service to improve the
health of patients in the upstate. We have an IRB-approved protocol
investigating acute treatment of stroke with catheter-directed
intra-arterial therapies.
If you have any questions or would like more information, please don’t
hesitate to call Terri Haviland, RN, Special Procedures Nurse Coordinator,
at 455-5488.
For more information go to:
www.asitn.org and / or
www.scivr.org
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