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Cerebral Vascular Disease
Updated: 06/22/2004
Thrombotic (Ischemic) Stroke,
Hemorrhagic Stroke, and Cerebral Aneurysm
A cerebral vascular event (stroke) is defined as a sudden neurological
deficit in the brain caused by either ischemia (a lack of blood supply
to the brain) or a hemorrhage: 80% of all strokes occur due to arterial
blockage (ischemia), and 20% occur due to bleeding (hemorrhage). Hemorrhagic
strokes are classified as either occurring within the brain tissue (intracerebral
or intraparenchymal) or around the brain tissue (subarachnoid).
Incidence and Epidemiology
Stroke is the leading cause of disability in the United States and the
third leading cause of death. While it was originally estimated that annual
stroke incidents were approximately 550,000 cases, a study in 1998, through
more rigorous counting in all racial and ethnic groups, increased the
yearly estimate to 731,000 cases (Broderick et al. 1998). This study showed
that African Americans have a higher stroke incidence and stroke mortality
than other racial groups.
Women have lower stroke rates than men at all age ranges except 75 years
and older, when stroke rates are at their highest. It is of concern that
the overall declining rate of stroke-related deaths slowed over the past
several decades and leveled off in the 1990s (Gillum 1999).
Individual approaches for the management of ischemic and hemorrhagic
stroke are discussed under Thrombotic Stroke and Hemorrhagic Stroke in
this protocol. Also, the terms thrombotic and ischemic stroke will be
used interchangably.
Prognosis and Recovery
In spite of conventional advancement in acute stroke care, the majority
of stroke survivors remain permanently partially disabled with neurological
symptoms and limitations. While most patients develop some improvement,
it is rarely complete. The more severe the initial stroke, the greater
the chance of long-term disability. Recovery also varies depending on
the size and location of the infarction or hemorrhage. Small infarctions,
especially multiple small stroke sites, may result in little disability,
whereas large infarctions may cause severe permanent disability.
It is interesting that other related conditions such as high blood pressure
do not appear to affect recovery. However, younger patients have a better
prognosis than older patients. Overall there is marked variability in
recovery, making early disability predictions difficult. In general, recovery
is greatest in the first 3 months and rarely occurs beyond 1 year after
the stroke. This makes it essential that speech therapy, physical therapy,
and occupational therapy be instituted as soon as possible after the stroke
occurs and continued three to five times weekly throughout the first year
of recovery. All too often, rehabilitative therapy is too infrequent and
is stopped prematurely preventing optimal recovery.
Recovery from strokes is relatively poorly understood. While infarcted
brain tissue is not able to repair itself, recovery has been theorized
to occur by recruiting neighboring neurons (nerve cells) to serve new
or additional functions. It is fascinating that electrical brain mapping
in monkeys has demonstrated that the cerebral cortex can be functionally
reorganized during recovery after an infarction (Nudo et al. 1996). In
fact, MRIs in humans have shown increased activity in both hemispheres
as patients improve after a stroke. This suggests recruitment of neighboring
neurons as well as the corresponding larger regions of the cortex (Cramer
et al. 1997).
If you or someone with you is possibly having a stroke, respond immediately!
The time it takes to receive treatment is as important to stroke victims
as it is for those who are having a heart attack. Not recognizing the
symptoms of a stroke, or believing that stroke is untreatable, causes
many people to fail to respond to the warning symptoms of stroke and to
not seek immediate medical attention.
Regardless of whether the stroke is thrombotic (caused by a clot) or
hemorrhagic, management at the onset is considered an acute medical emergency.
Stroke patients receiving medical care within 6 hours of the onset of
symptoms have a 32% greater chance for a reduced hospital stay (13 days
versus 19 days) than those treated after this period (Davalos et al. 1995).
Amazingly, 42% of stroke patients wait as long as 24 hours before presenting
for medical treatment. That is 21 hours too late! The delay in presenting
at the emergency room results in a missed opportunity to effectively treat,
and possibly reverse, the damage caused by thrombotic stroke. According
to one study, "patients with milder symptoms, for whom treatment
might be more effective, were less likely to arrive in time for therapy"
(Alberts et al. 1990).
From a preventive medicine and patient education perspective, it is therefore
crucial that healthcare providers educate at-risk patients and their families
about stroke-related symptoms and encourage them to call 911 if stroke
symptoms occur. It is equally crucial that optimal emergency room intervention
and treatment occur as soon as the patient arrives in the hospital emergency
room.
From the time the patient arrives at the emergency room (ER) triage desk,
a computerized tomography (CT) scan should be authorized as soon as possible
(within 5 minutes). Multiple timely interventions are crucial in the acute
emergency room. These vary based on a range of findings including the
patient's temperature, oxygen saturation, blood pressure, glucose levels,
complete blood count, electrocardiogram, airway and pulse, medical history,
and hydration status. Inclusion and exclusion criteria are reviewed for
the consideration of intravenous (IV) thrombolytic therapy if a thrombotic
CT scan pattern is identified. The CT scan is further reviewed distinguishing
a thrombotic stroke from an intracranial or a subarachnoid hemorrhage.
A neurosurgeon will be consulted if an aneurysm or blood pooling is present
due to an intracranial hemorrhage. Surgery may be necessary for the evacuation
of a hematoma (blood pooling from a hemorrhage). In the intensive care
department, blood perfusion (hemodynamics) is continually monitored and
assessed. Secondary stroke prevention is initiated based on National Institutes
of Health (NIH) guidelines. The treatment of stroke patients in dedicated
stroke units has been shown to reduce morbidity, mortality, and disability
as well as other post stroke complications (Indredavik et al. 1999).
Stroke-Related Symptoms
The sudden onset of neurological signs and symptoms developing over a
few minutes or few hours are indicative of a stroke event. Most of these
strokes will be ischemic, involving a thrombus (clot), rather than hemorrhagic.
However, any of the following symptoms can result from a clot or bleed,
depending upon the arteries in the brain involved in the stroke and their
location.
According to the National Stroke Association (1999), strokes more often
occur abruptly, with the following symptoms which often develop suddenly:
- Difficulty standing or walking, dizziness, loss of balance, loss of
coordination
- Numbness in the face, arm or leg weakness, particularly on one side
of the body
- Confusion, difficulty speaking or understanding
- Vision difficulty in one or both eyes
- Severe headaches that have no known cause
- Other important, but less common stroke symptoms include:
- Nausea, fever, and vomiting that is different from a viral illness
in the speed of onset (begins in minutes or hours instead of over several
days)
Normal Functional Areas of Brain
The brain has two sides: a right hemisphere that controls the left side
of the body and a left hemisphere that controls the right side of the
body. Each hemisphere has four lobes and a cerebellum that control our
daily functions. Depending on what part of the brain has been affected,
stroke victims experience a variety of neurological deficits. Rehabilitation
is crucial to the stroke patient's recovery. Physical therapists and speech
therapists help patients "relearn" their lost functions and
devise ways to cope with the loss of those they cannot regain. (Anatomical
Chart Company 2002®, Lippincott Williams & Wilkins)
A brief loss of consciousness or a period when there is a reduced level
of consciousness (sudden fainting, increased confusion, convulsion, or
coma)
Any of these signs may be only temporary and may last only a few minutes.
Hemorrhagic Stroke Symptoms
When a bleed occurs, causing a stroke, the symptoms are less abrupt over
one or several hours. The most commonly associated symptoms include headaches,
vomiting, and altered states of consciousness.
Cerebral Embolism Symptoms
Symptoms vary further depending upon the nature of the developing stroke.
If the stroke is caused by a thrombus (clot) suddenly passing into arteries
in the brain (cerebral embolism), the symptoms are of rapid onset, often
intensifying over a few seconds, causing headaches on the affected side,
seizures, or both. There is often a preexisting heart disease, such as
mitral stenosis or atrial fibrillation, endocarditis (an inflamed heart),
or a mitral valve prolapse, in which stagnant blood has had the chance
to clot and then pass from the heart suddenly into arteries of the brain,
blocking blood flow to the brain.
Cerebral Thrombotic Stroke Symptoms
When a cerebral artery becomes blocked from the progressive worsening
of a localized clot or a hardened artery in the brain, the symptoms develop
over minutes or hours and sometimes over days or weeks. Common causes
include gradual hardening and narrowing of cerebral arteries (atherosclerosis)
often associated with hypertension, diabetes, coronary artery disease,
peripheral vascular disease, or head trauma.
Transient Ischemic Attacks
Often patients can experience temporary symptoms that are associated with
a lack of adequate blood supply to the brain. These episodes are known
as transient ischemic attacks (TIAs). When TIA-related symptoms occur,
they occur suddenly and last from 5 minutes to several hours and then
resolve completely. These symptoms are often due to reduced circulation
and blood supply from the two main arteries leading into the brain--the
carotid arteries located in the neck supply the brain from the front,
and the vertebrobasilar arteries supply the brain from the back, passing
through holes in the vertebrae of the cervical spine.
The peak age of onset for TIAs is 60-70 years of age. It is interesting
that a third of the time, TIAs will lead to a subsequent stroke; a third
of the TIAs continue and do not lead to a stroke; and a third of the time
TIAs spontaneously remit and no longer occur.
It is commonly agreed that TIAs are due to microembolization (small clots
moving into the brain), excessive platelet aggregation, or from ulcerations
in the walls of atheromatous hardened arteries. Other causes include transient
episodes of low blood pressure due to dehydration or adrenal insufficiency,
mechanical kinking of arteries in the head and neck during head rotation,
cervical spine bone spurs compressing the vertebrobasilar artery, or heart
arrhythmias.
TIA symptoms are artery-location dependent. Here is a list of the arteries
and brain regions that may be temporarily restricted in blood supply and
the associated symptoms that develop.
| Location |
Related Symptoms |
| Carotid artery |
Effects retina, cerebral hemisphere, or
both. |
| Retinal |
Transient blackouts; the sense of a shade
pulled over the eyes. |
| Cerebral |
Contralateral (opposite sided) paralysis
of a single body part; paralysis of one side of the body; localized
tingling, numbness; hemianopic visual loss; aphasia (loss of speech);
rare loss of consciousness. |
| Vertebrobasilar |
Bilateral visual disturbance including
dim, gray, or blurred vision or temporary total blindness; diplopia
(double vision). |
| Labyrinth/medulla |
Vertigo; unsteadiness; nausea; vomiting.
|
| Brainstem |
Slurring dysarthria (tongue weakness causing
impaired speech); dysphagia (difficulty swallowing); numbness, weakness;
all four limb paresthesia; drop attacks from sudden loss of postural
tone are basilar in origin; a vertebrobasilar artery occlusion episode
causes symptoms to be induced by abrupt position changes. |
Subclavian Steal
syndrome |
Symptoms of claudication (lameness or limping)
of an exercised arm with symptoms of vertebrobasilar insufficiency
described above. |
Thrombotic Stroke
Ischemic, Thrombotic, Embolic, and Transient Ischemic Attack
In this section, we will discuss methods of preventing primary
and secondary thrombotic (ischemic) strokes, along with approaches to
restoring function to brain cells that are damaged by a thrombotic stroke
(i.e., inducing or accelerating rehabilitation, or both). Because some
people may refer to this protocol if they have symptoms of an acute stroke,
we will begin with the initial steps involved in diagnosis and immediate
treatment.
Aggressive Stroke Therapy
Healthcare providers still do not treat stroke as aggressively as they
do heart attack. Many therapies that are proven to work are not made available
to the acute stroke patient presenting in the emergency room.
Further contributing to stroke deaths is the belief by many healthcare
providers that stroke is untreatable, leading to an attitude of "watchful
waiting" with an onset of a stroke instead of being focused on treating
the stroke as a medical emergency. The National Stroke Association has
described this opinion as being an outdated attitude that serves as the
largest obstacle to effective prevention and emergency treatment of strokes.
The use of CT and Doppler ultrasonography has made radical changes in
early diagnosis of ischemic and hemorrhagic strokes (Wintermark et al.
2002). These advances have resulted in declines in stroke mortality. In
the 1980s, the development of magnetic resonance imaging (MRI) further
improved evaluation of persons with cerebrovascular disease (Hesselink
1986; Welch et al. 2000).
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