Aspects/Prevention of Cerebral Vascular
stroke or cerebral
vascular accident (CVA) is a temporary or permanent
loss of functioning brain tissue caused by an interruption
in the cerebral blood supply. This interruption is typically caused by plaque. Recent technology using magnetic resonance imaging (MRA) is being used to evaluate the resulting thrombosis and stenosis in the arteries. The term "brain attack" is now
being used by many to refer to stroke.
people have strokes in the U.S. every year. Brain
infarctions account for about 75% of strokes, while
intracerebral or subarachnoid hemorrhages for about 15%.
(Gresham, G., Duncan, P., Stason, W., et al. 1995).
According to the National Stroke Association there are
approximately 160,000 deaths per year in the United States
from stroke. Most strokes correlate with
hypercholesterolemia, or excessive levels of cholesterol in
the blood. There may be other factors as well because many
individuals with high levels of cholesterol do not get
strokes. Diabetes and stroke are closely linked, because
many of the risk factors for diabetes are also risk factors
for stroke. They include high cholesterol levels, obesity,
family history, and lack of exercise. Diabetics have other
risk factors that make them generally more prone to stroke
and heart disease. They include high levels of
triglycerides and low levels of high density lipoprotein,
the good cholesterol. Diabetics also have a tendency to form
clots. Smoking is another serious risk factor for
A family of drugs
called statins include Mevacor, Pravachol, Zocor, Lescol,
Lipitor and Baycol. Baycol is a trademark used for the drug
cerivastatin. It was pulled off the market in 2001 because of muscle destruction linked to 31 deaths in
the United States and at least 9 additional fatalities
abroad. Statins are used safely by millions of Americans and
others around the world to lower cholesterol levels. While
these drugs work well for most, some people have a very rare
but dangerous side effect which results in muscle
destruction. People suffering muscle pain/tenderness or
weakness should notify their physicians immediately. They
may have rhabdomyolysis, a life threatening condition in
which muscle cells are released into the bloodstream. Niacin is another treatment option to raise good chosterol and lower bad chosterol and triglycerides. It is often used alone or with statins and is much safer. Dr. John Kastelein, 2008, a Dutch scientist led a study comparing the efficacy of Vytorin, a combination of ezetimibe (Zetia) and simvastatin (Zocar), and simvastatin alone. The results indicate that simvastatin alone was much better that Vytorin at reducing plaque. This was true even though Vytorin was very successful at lowering LDL and triglycerides. Vytorin had no added benefit in reducing plaque.
There are two
principal kinds of strokes, ischemic and hemorrhagic. Both types cause
infarction, or death of brain
tissue. Ischemic strokes typically result from arterial blockage. The gold standard has been angiography where a catheter is place in the formoral artery in the groin and threaded up through the arteries to the heart or brain. It's invasive especially for arteries that supply blood to the brain. A magnetic resonance imaging technique called MRA is now used to look at artery blockage or stenosis. The image you just saw is that of an arterial venous malformation (AVM). Please look at the video of a woman who had a stroke due to an AVM.
Other recent medical advances may offer hope to many
stroke patients. At a meeting in San Francisco of the
American Association for the Advancement of Science, Dr.
Paul Sanberg of the University of South Florida described
his stem cell research. Cells recovered from umbilical cords
may be useful for repairing brains damaged by stroke. In
experimentation with animals these cells were infused
through the blood stream without the need for surgical
implantation into the brain. Dr. Sanberg is hopeful that
this approach can be used with human stroke victims within
the next two years. In experiments with rats, Sanberg's team
found that those given the cells had recovered about 80%
from the strokes, while the control group (untreated rats),
had made only a 20% recovery. Sanberg feels that the
treatment works best when give within 24 hours of injury.
According to Sandberg, just how the new cells rewire the
brain is unclear even though the cells can take on the form
of different types of brain tissue. He also said that one or
two umbilical cords could very likely be enough to treat one
human stroke victim. He cautions that many things such as
immune system responses and the numbers of cells to be
infused have to be worked out before any treatment can begin
different approach to helping stroke victims recover is the
lowering of body temperatures. At a meeting of the American
Stroke Association in Fort Lauderdale, Florida, Dr. Derk
Krieger from the Cleveland Clinic described how he and his
colleagues used hypothermia (alcohol rubs) to quickly reduce
body temperature of patients following severe strokes. In
order to prevent shivering, the patients had to be
temporarily paralyzed, put on breathing machines, and
rendered unconscious. It is still an experimental procedure,
which may be very uncomfortable, and result in
complications. Even so, of the ten patients who underwent
the procedure, five had no permanent damage.
The FDA has
approved the use of thrombolytic therapy (t-PA) for the
treatment of acute stroke within three hours of onset of
symptoms (Atkinson, 1997). According to Dr. Atkinson, in a
NINDS t-PA for stroke trial, patients treated with t-PA
therapy improved regardless of the suspected etiology of the
stroke. However, episodes of systemic bleeding in the 10
days after therapy were 6.4% with t-PA and 3.8% with a
placebo. The study which treated 624 patients showed that
patients treated with t-PA were 30-50% more likely to have
minimal or no disability at three months. A surprise finding
of the study was that patients treated within 90 minutes
after onset of symptoms did not do better than patients
treated after three hours. Also, there was no evidence that
transient ischemic attacks (TIA's) played a role in the
study, because only 2% of placebo treated patients were
normal at 24 hours. Remember, a TIA presents with stroke
symptoms but they go away within a day, leaving the patient
pretty normal. The New England Journal of Medicine on 9/25/'08 reported that the 3 hour window to administer t-PA after symptoms start has been increased to 4.5 hours. Apparently the clot dissolver can be safely given more than an hour longer than the previous recommendation.
treatment for ischemic stroke that has been investigated is
the use of a direct thrombin inhibitor. According to Marion
LaMonte, 2001, the drug Argatroban was examined for
safety and efficacy in patients with acute ischemic stroke.
With ischemia, blood supply to the brain is interrupted
either by a blockage or a narrowing of an artery. Argatroban
is an anticoagulant. It may work on dissolving the primary
clot as well as affecting the microcirculation around the
area of the original blockage. According to Michael Chopp,
Ph. D. 2001, Vice Chair of neurology at Henry Ford Hospital,
in studies with rats, combining Argatroban with t-PA at
four hours post onset has potential to open the window of
opportunity for stroke treatment without increasing
intracranial bleeding. Another study examined the
experimental drug DHA. This antioxidant scavenges oxygen
free radicals that can play a major role in tissue damage.
During a brain attack there is a reduction in blood flow.
This permits free radicals to affect the body's ability to
neutralize toxins. DHA is a derivative of ascorbic
acid-vitamin C. After DHC is transported across the blood
brain barrier it is converted into vitamin C.
term "ischemia" refers to a lack of blood-borne oxygen.
Ischemic strokes are more common than hemorrhagic strokes
and may be caused by stenosis or thrombosis of the arteries, as well
as by the presence of thrombo-emboli in the arteries. Check out the Department of Neurology at Debrecen University Medical School, Hungary.
Stenosis is a general term that
means narrowing. In this case, it refers to the narrowing of
an artery due to the build-up of plaque. As the artery is
not completely blocked, some blood passes through it.
However, if 50% of normal blood pressure is not
maintained, brain damage will occur.
Thrombosis refers to the total
blockage of an artery due to plaque build-up or
There are a number
of drugs taken for heart and circulatory disease that have
been shown to slow the build up of plaques that block the
internal carotid arteries. The internal carotids take blood
to the middle cerebral and anterior cerebral arteries.
Blockages in the internal carotids can result in stroke that
affects language, speech, and cognition. A study by
researcher Dr. Goran Berglund (2001) and his team at Malmo
University in Sweden that came out on in the American Heart
association Journal, Circulation, reported the first
evidence that a beta blocker can slow progression of plaque
in the internal carotids. The drug used was metoprolol. It
slowed the buildup rate by 40% in otherwise healthy people
who had plaque buildup with no overt symptoms. The study
involved 793 people aged 49 to 70. Another study by
researchers in Canada, also reported in Circulation, showed
that ramipril, an ACE inhibitor, slowed the formation of
plaques in the internal carotids.
Currently only tissue plasminogen activating agents (t-PA) is approved by the FDA for therapy for acute ischemic
stroke. This potent medicine carries with it a
risk of cerebral hemorrhage. According to Bhatnager, 2008, it must be administered intravenously within three hours of CVA onset or inter-arterially within six. Drugs that inhibit platelets such as aspirin and Plavix are often used after a person has transient ischemic attacks. Many people who are at risk for stroke are advised by their doctors to take an 80mg aspirin every day.
Thrombo-emboli are pieces of plaque which
break loose from thrombi and travel through the arterial
system until they reach a narrow area and lodge, cutting off
the blood supply to brain tissue beyond that point. This can
occur when a normally sedentary person engages in strenuous
TIAs or Transient
types of temporary ischemic events are warning signs that a
true stroke is likely to occur in the near future. They
are transient ischemic attack (TIA) and reversible ischemic neurological defect (RIND).
transient disturbances of the blood supply to a localized
part of the brain, which produce a temporary, focal lesion.
Unlike strokes they resolve in spontaneous and complete
Symptoms of TIAs mimic those of stroke. These attacks may
cause temporary aphasia, numbness, and impair speaking,
reading, and writing abilities. Dizziness and visual
problems, such as blindness in part of the visual field, can
also occur. Sometimes, TIAs are very mild and involve only
numbness in a limb, or loss of sight in one eye. Severe TIAs
cannot be differentiated from a stroke until recovery
A TIA typically last between 2 and 15 minutes, although such
an event could conceivably last as long as 24 hrs. It is
also possible to have a series of many brief TIAs during one
day. For example, a patient might have 10 or more transient
ischemic attacks within a 24 hr. period.
As mentioned above, drugs such as aspirin or Plavix are often prescribed after a TIA.
RIND or Reversible
Ischemic Neurological Defect
A RIND is a lengthy
TIA. The term RIND is usually applied to attacks that
continue for more than 12 hours without interruption,
although some may last for several days. As with a TIA, a RIND will resolve in complete recovery, however
some neurologists do not consider them temporary. (There is
some evidence that RINDs do cause some subtle neurological
damage, but these minor changes are nothing like the types
of disabilities seen after "real" strokes.)
Ischemic strokes, as well as TIAs and RINDs, are more likely
to occur early in the morning. During sleep, blood pressure
is at its lowest level. When a person gets out of bed, the
sudden increase in blood pressure due to this change in
activity level can cause an embolism to break free.
Hemorrhagic stroke occurs when a
cerebral artery ruptures, causing bleeding within the
cranium. Such ruptures may be caused by aneurysms or weak spots in arterial
walls. (Aneurysms can balloon out rather than bursting. The
excess pressure resulting from this swelling can also damage
brain tissue.) Bleeding due to stroke can cause the
formation of hematomas, or pools of congealed
blood, in the epidural space, or the subdural
Intraparenchymal bleeding refers to the flow of blood
into brain tissue rather than into an existing space like
space or a potential space like the subdural space. The term "parenchyma" means "specific cells of
a gland or organ" (Stedman's Concise Medical Dictionary. 1997) Parenchymal
hemorrhages occur most frequently in the putamen (part of the lenticular nucleus), thalamus, pons, or cerebellum (Coch
& Metter, 1994). The striata artery which supplies the
internal capsule with blood is quite thin and easily
hemorrhages. This is why it is called the artery of stroke.
Before the advent
of sophisticated scanning techniques that allow the
identification of small as well as large hematomas, it was
believed that prognosis after a hemorrhagic stroke was
extremely poor. Now it is recognized that patients often
make a better recovery after a hemorrhagic stroke than after
an ischemic stroke. Slow parenchymal bleeding may irritate brain tissue
rather than damaging it. As the brain absorbs some of the
blood flow from the hemorrhage, these areas heal and begin
to function again. It is possible for a patient to make a
complete recovery from a hemorrhagic stroke.
Because it frequently occurs at a very slow rate and over a lengthy period, neurological problems due to parenchymal bleeding may have an extended spontaneous recovery. For this
reason, it may justifiable to continue therapy for a longer
period of time with patients who have had parenchymal
bleeding than with those who have had other types of
Strokes can also
be divided into the categories of completed or progressive.
Completed strokes are the type most
commonly seen. In this case, the infarction of brain tissue
has ceased to occur.
Progressive strokes are those that are
still evolving, meaning that the patient's condition is
continuing to deteriorate. Progressive strokes can last for
a week or more. This condition is usually the result of a
If called in to
evaluate patients with this diagnosis, the SLP should test
the patients but explain in the report that major changes
could occur shortly. Even if their aphasia is initially mild it could worsen. Particular caution should be used when
evaluating the swallowing status of such patients. They may
be able to swallow safely initially, but develop dysphagia
later as their condition worsens. Also, progressive strokes
tend to happen to people who have very poor cerebral
vascular health and are therefore at risk for having another
stroke very soon. Cerebral vascular accidents are only some of the medical conditions that result in aphasias and right hemisphere syndrome. Also included are tumors and metabolic encephalopathy. In addition patients may have dementia. I just read a study on coffee and prevention of dementia.