|
Strokes
Strokes affect 700,000 people each year, and are the third leading
cause of death in the United States, accounting for about 1 in every
14 deaths. Someone in the US has a stroke, on average, every 45
seconds, and someone dies from stroke every 3.1 seconds. It is
estimated that 40,000 more women have strokes each year than men.
More money is spent on the care of strokes than any other condition.
More than 1 million Americans suffer from difficulty in daily
functioning due to stroke.
Strokes typically occur when an artery
that supplies blood to the brain is blocked. This is known as an
“ischemic” stroke, and it is believed to account for over 80% of all
strokes. As a result of an ischemic stroke, the brain will not
receive enough blood in the area of the blockage and neurons start
to die of starvation from lack oxygen and energy sources. If the
blocked blood vessel is not reopened, loss of brain function may
quickly occur in areas controlled by the affected part of the brain.
Strokes may also occur when a blocked artery bursts, causing
bleeding around the brain. This is referred to as a “hemorrhagic”
transformation of an ischemic stroke and represents a serious risk
to the stroke victim with or without medical intervention.
Risk factors
A number of medical conditions are risk factors for stroke. These
include diabetes mellitus, hypertension, atrial fibrillation (one
type of irregular heartbeat), and atherosclerosis, commonly known as
hardening of the arteries. Diseases that cause blood to form clot
too quickly or easily and are affiliated with blockages in blood
vessels in other parts of the body also can contribute to strokes.
Family history of stroke and prior personal history of stroke also
put one at greater risk. Certain ethnic groups, including African
Americans, Latinos, and Asian Americans are also more likely to get
strokes than other populations.
Several symptoms can be warning signs of stroke and are cause for
immediate medical treatment. For example, rapid onset of weakness or
numbness, confusion, visual difficulties, and speech problems may be
evidence of stroke. Additional warning signs include dizziness, loss
of balance, or difficulty with coordination. Unfortunately,
sometimes strokes also cause neglect or the inability on the part of
the stroke victim to recognize that the stroke has occurred. For
example, the stroke victim may be paralyzed on one side of their
body but also fail to recognize that the affected body part even
exists.
Diagnosis of stroke
In order to accurately diagnose a stroke, physicians may utilize one
of several different types of diagnostic procedures. Computed
tomography, or CT scan, of the brain is a type of x-ray imaging
study that allows physicians to evaluate the brain for evidence of
stroke and other conditions that may mimick stroke, such as tumors
and infections. CT scanning may also show if normal brain tissue has
suffered any damage. CTangiography or CTA, is an enhanced form of CT
scanning in which a special iodinated contrast isinjected through a
vein at the time the CT scan is performed. Blood vessels can then be
examined for blockages, aneurysms or other causes of stroke and
hemorrhage. A conventional cerebral angiogram also involves the
injection of an iodinated contrast material, but this is through a
tiny catheter or tube measuring approximately 1.5 mm in diameter
into the arterial blood vessels to examine the flow of blood at the
most detailed level. Catheter angiography also forms the basis for
endovascular surgery now used to treat many forms of stroke and
other cerebral vascular abnormalities.
Magnetic resonance imaging, or MRI, is another type of study that
allows blood vessels and brain tissue and function to be examined.
MRI is very sensitive to the identification of early brain ischemia
or bleeding. MRI scanning often requires more time to perform. In an
emergency, CT brain scanning remains much faster and more easily
obtained in most hospitals. CT scanning is able to identify most
acute hemorrhages that occur in and around the brain. In fact, most
major studies evaluating patients with forms of stroke or hemorrhage
have been based upon CT scan findings. If a CT is normal or
“negative” but the physician remains suspicious that hemorrhage has
occurred, then a lumbar puncture to may be necessary to evaluate for
very subtle bleeding that could be indicative of a life-threatening
condition. A lumbar puncture or “spinal tap” is performed to obtain
a small sample of spinal fluid for evaluation. This involves the
insertion of a needle into the lumbar (lower back) spinal canal
below the level of the spinal cord to withdraw cerebrospinal fluid –
the fluid that is produced deep in the brain and bathes brain and
spinal cord. Spinal fluid analysis is another very sensitive
indicator of hemorrhagic stroke and some other causes of
neurological dysfunction.
Treatment of Ischemic Stroke
There are a number of procedures to treat acute stroke. There is
still a tremendous amount that remains unknown about brain function,
the response of brain tissue to ischemia, and mechanisms to prevent
cell death and dysfunction before medical care can be administered.
Blockages in brain blood vessels can sometimes be cleared or
dissolved and the effects of the stroke on brain function reversed.
In some cases, drugs that dissolve blood clot can be administered to
restore blood flow to the brain. Injection of tissue plasminogen
activator, or TPA, can be administered by vein to patients with
ischemic stroke but no bleeding if the drug can be administered
within three hours of stroke onset. Intravenous thrombolysis is
currently the only therapy approved by the U.S. Food and Drug
Administration based upon the findings of a single multi-center
trial. However, the vast majority of stroke victims do not present
for medical attention within this three hour window. Moreover, large
vessel occlusions that threaten large areas of the brain do not
respond well to intravenous thrombolysis For these reasons and
others, physicians are working to develop more effective, safer, and
faster methods to treat acute stroke.
Interventional stroke treatment from start to finish
Prior to undergoing endovascular stroke treatment which is
effectively a form of surgery, patients or their legal guardian or
representative must sign a consent form and will have the
opportunity to have questions answered. In certain very specific
cases, this type of emergency treatment can be performed in an
effort to help the stroke victim with waiver of informed consent.
But waiver of informed consent requires adherence to strict
guidelines and must usually be performed with prior approval of the
institution’s investigational review board (IRB).
An anesthesiologist will administer medications and fluids
through the use of an intravenous line (IV) into a vein in the hand
or arm. In some cases, general anesthesia with the patient
completely asleep on a respirator is required for stroke victims who
are unable to cooperate for the catheter arteriogram and
endovascular stroke treatment.In many cases, the stroke patient can
be treated under light sedation and can remain in constrant
communication with the treating physicians. Blood pressure may be
monitored through an A-Line, a thin flexible tube or catheter placed
in an artery in the wrist. An electrocardiogram (EKG) will monitor
heart rate and rhythm. And an oxymeter provides a non-invasive
method to monitor the patient’s respiration and bloodoxygen levels.
A specific type of catheter known as a Foley may be placed through
the urethra, into the bladder to allow urine to drain.
Anesthesiologists often monitor urine output as a simple indicator
that the body’s major systems are functioning well.
The arteriogram to diagnose the location of the blockage and the
pathway for endovascular treatment most often involves the insertion
of a small catheter or tube into the common femoral artery, the
major artery to the leg. The treating physician, usually a
specialist in interventional neuroradiology or endovascular surgical
neuroradiology, guides the catheter using advanced x-ray imaging
technology called fluoroscopy into the site of the blocked artery.
Through these catheter systems, medicine such as TPA or other agents
to dissolve clot, relieve spasms, or protect the brain can be
administered. Direct disruption of the blockage using balloon
angioplasty or passage of the catheter through the center of the
blood clot promote more rapid restoration of blood flow. Moreover,
new and inventive treatments to mechanically remove the blockage are
now under development that may offer even greater safety and
efficacy than thrombolysis.
Once the procedure is complete, the patient will be transferred
from the neuro-interventional operating room to either the
Neurological Intensive Care Unit (NICU) or the Post-Anesthesia Care
Unit (PACU). Following successful stroke treatment, patients must be
carefully monitored for any evidence of hemorrhage into the injured
brain tissue that would require emergency surgery. Their blood
pressure must be carefully controlled, and heart monitoring to
detect early signs of heart attack is continuously performed. Here,
a heart monitor will closely monitor vital signs. This machine is
very sensitive and often sounds inadvertently; this is not cause for
alarm. The nursing staff will assist in changing positions, but bed
rest is required. In some centers, additional medical interventions
are under investigation to restore normal brain function.
Eventually, the patient can look forward to a normal diet and
transfer to a room on a neurological care floor. The Foley catheter
and any invasive vascular monitors will also be removed prior to
leaving the bed for the first time.
Patients are expected to keep the leg that underwent surgery
straight for several hours. In most cases, the arterial treatment
catheter is removed at the end of the procedure and a special
percutaneous suture device is used to seal the hole in the artery
without open surgery. A short tube may remain in place at the
arterial access site for up to 24 hours after administration of TPA
or other clot-busting medicine until the drug effect has worn off.
Thereafter the tube can be safely removed.
The length of stay in the hospital will depend on the severity of
the stroke, the need for rehabilitative therapy, and other medical
conditions that may require treatment. Once at home, certain
activities such as heavy lifting and driving must be avoided until
the physician provides approval. Many patients, however, can resume
normal activity after a relatively brief period.
All treatments for acute stroke require immediate action. When a
brain blood vessel becomes blocked depriving the brain of oxygen and
energy, “Time is brain” as irreversible brain damage can occur
within minutes of stroke onset. Therefore, one must not hesitate
seek emergency medical care whenever a stroke is suspected. Delays
in seeking medical attention and treatment until it is too late are
the most common way in which stroke patients present to their
doctors. The importance of recognizing the symptoms and the need for
urgent medical care cannot be overstated. |
