Used with Permission from:
MGH 1996 A Magazine for the
General Hospital Community
The warning symptoms may be subtle and last only a few minutes weakness
in an arm or leg, dizziness, double vision, difficulty speaking. But such experiences
never should be ignored because they could be signaling the approach or even the
beginning of what could be a catastrophic event: a stroke.
stroke always has been a medical emergency. The sudden loss of blood supply to
part of the brain, caused by blockage or rupture of a blood vessel, puts in jeopardy
an individuals ability to walk, to speak, even to think. New diagnostic
and treatment methods, many pioneered at the MGH, now have the potential to save
lives and prevent some of the most devastating consequences of stroke, making
it more important than ever to seek medical attention at the first sign of a possible
methods, however, have a catch.
They must be used within a few hours of a strokes onset or they may be ineffective
or even do more harm than good.To emphasize the urgency of a stroke and the need
for rapid treatment, specialists at the MGH and around the country have begun
using the term brain attack.
know very well that heart attacks need immediate attention. We hope to convey
this same sense of urgency by calling strokes brain attacks, says Walter
Koroshetz, MD, who leads the Acute Stroke Treatment Team in the MGH Stroke Service.
In some ways, strokes can be even more damaging than heart attacks. If part
of your heart muscle is permanently damaged, you may be able to continue living
a fairly normal life. But if you lose a crucial portion of your brain, youre
a different person.
The MGH Stroke Service concentrates its research efforts in two primary areas:
stroke prevention and acute stroke treatment. Philip Kistler, MD, director of
the service, explains that both areas follow the services longtime philosophy:
to identify the exact physical problem that causes a patients stroke or
risk of stroke and
direct prevention and treatment efforts toward that condition. Another area of
study is investigating treatments to help patients recover from stroke with less
vast majority of strokes result from a blood clot blocking a vessel supplying
the brain. Most of these ischemic (loss of blood supply) strokes have one of three
causes: blood clots that form
in the heart or major arteries and travel to the brain, blockage of tiny vessels
deep within the brain or the buildup of atherosclerotic plaques in major arteries
supplying the brain.
blockages usually are associated with chronic high blood pressure or diabetes,
control of which can effectively prevent a stroke. To prevent strokes related
to plaque buildup, the plaques in major arteries may need to be removed surgically.
If plaques are identified early enough, their size may be limited by making lifestyle
changes stopping smoking, reducing fat in the diet and increasing exercise
and taking cholesterol-lowering medications.
Prevention of strokes caused by blood clots, which account for 60 percent of ischemic
strokes, took a major step forward when an MGH research team led by Kistler showed
that the blood-thinning drug warfarin prevents strokes in patients with a rapid,
irregular heartbeat called atrial fibrillation. This condition causes clots to
form in the upper chambers of the heart. The clots can break off and travel to
the brain. The researchers estimate that appropriate use of warfarin could prevent
more than 50,000 strokes each year in the United States.
and his colleagues now are conducting several studies to further investigate how
factors in a patients blood may interact with how well the heart functions
to produce stroke-causing clots not associated with fibrillation.
All of our stroke prevention
efforts rely on very close cooperation with colleagues in internal medicine, cardiology,
hypertension, vascular surgery and neurosurgery here at the MGH, Kistler
says. Weve also set up collaborations with internists and specialists
at Brigham and Womens Hospital, elsewhere in the Partners network and at
other local health care institutions. The collaborations will include joint
clinical research projects and sharing clinical experiences with both preventive
therapies and exciting new approaches to acute stroke treatment.
approach generating a lot of attention lately is to dissolve stroke-causing clots
with the same kind of thrombolytic or clot-busting drugs that have
revolutionized treatment of heart attacks. Last December a National Institutes
of Health-sponsored study reported that injections of a drug called tissue plasminogen
activator (TPA) reduced long-term disability in a carefully selected group of
NIH study provided the first hard evidence supporting what we have contended for
years: Getting patients to the hospital quickly gives us the best chance of minimizing
brain damage caused by a stroke, says Koroshetz. He explains that any clot-dissolving
treatment must be applied quickly for two reasons. The
faster blood flow is restored, the less brain tissue will be damaged. But
if the blood supply is restored after too much damage has occurred, the patient
will suffer a dangerous hemorrhage in the brain.
the blood supply is cut off to an area of the brain, tissues go through a series
of stages before they die. Eventually the walls of the blood vessels in dying
areas begin to break down, he explains. If you restore blood flow
to an area where the vessels have been damaged, youll have a hemorrhage.
This is almost invariably fatal.
of this danger, doctors considering thrombolytic treatment must carefully weigh
the risk of hemorrhage against the benefits of treatment. The judgment leads to
what was until recently an unanswerable question: How much of a patients
brain will be affected by the stroke? New brain imaging techniques are able to
answer this question soon enough to help make that crucial decision.
Traditional brain-imaging technology CT scans and standard MRI examinations
cannot confirm the presence and location of a stroke until eight or more
hours after its onset. But a new form of MRI largely developed by researchers,
led by Bruce Rosen, MD, in the MGH Radiology Department can diagnose a stroke
almost immediately. Furthermore, refinements of the technique, called functional
MRI, show not only where the stroke has already damaged brain tissue but also
where further damage is likely to occur if a vessel-blocking clot is not removed.
patients stroke is very small and not going to spread to other areas of
the brain, Koroshetz says. For someone like that, you wouldnt
want to risk a hemorrhage. But some patients are in the first stages of what could
be a huge stroke, and now we can see just how large an area of tissue would be
damaged if blood flow is not restored. The consequences of such a stroke would
be so devastating that its worth using a risky treatment. The patient has
little to lose.
years ago Gilberto Gonzalez, MD, and Gregory Sorensen, MD, MGH neuroradiologists,
expanded the hospitals MRI capacity, allowing use of the most advanced functional
MRI techniques to diagnose any patient with a suspected stroke. The MGH was the
first and remains one of a handful of hospitals with such a capability. In collaboration
with the Interventional Neuroradiology group, led by In Sup Choi, MD, Koroshetz
and Ferdinando Buonanno, MD, of the Stroke Service are offering an experimental
clot-dissolving treatment to those patients most likely to benefit.
The MGH approach differs from
that of the NIH investigation. Instead of injecting TPA into a vein, which carries
it throughout the body, the radiologist passes a catheter directly into the artery
where the clot has lodged and delivers a clot-dissolving drug called urokinase
directly to the clot.
Our success rate in dissolving the clot is much higher with this intra-arterial
approach, 90 percent versus the less than 40 percent reported with the intravenous
technique, Koroshetz says. But intra-arterial is more invasive, complex
and difficult. You need the ability to locate and dissolve the clot quickly, and
you need sophisticated equipment and neuroradiologists with the expertise to carry
out a very delicate procedure.
believes that there is a place for both approaches. Intravenous injection will
be a first-line therapy applied as soon as patients arrive in the MGH Emergency
Department and a stroke diagnosis is confirmed. Intra-arterial treatment, probably
available only at tertiary centers like the MGH, would be a second option if the
intravenous therapy is not successful.
and his colleagues also are investigating drugs that have the potential to protect
brain cells against toxic molecules released when tissue is injured by lack of
blood supply. Protective substances called growth factors that may be able to
reduce stroke injury and aid brain recovery also are being investigated by Seth
Finkelstein, MD, and Koroshetz. And colleagues at Spaulding Rehabilitation Hospital
are studying how patients recover from stroke. Taken together, these new approaches
may revolutionize the outlook for what is still the number three cause of death
in this country.
says: The whole stroke community is now gearing up toward this more aggressive
approach of getting people in quickly to determine whether a stroke is occurring
and what its cause is. With that knowledge, physicians can apply appropriate treatment
to prevent further damage or recurrence. At the MGH weve always espoused
this approach, but because treatment options were limited, many physicians believed
that all you could do in stroke was comfort the patients and family members.
Now we know we can make
a difference. When members of our Acute Stroke Treatment Team are successful in
safely breaking up the clot, the patient gets better right before their eyes.
That is unbelievably gratifying.