Aneurysm
What is an
Aneurysm? An aneurysm is an
abnormal outgrowth in an artery or blood vessel that expands the
artery walls to form a miniature balloon filled with blood.
Progressive weakening of the aneurysm wall allows it to grow in
size.Further enlargement may result in pressure on the brain
structures producing neurological symptoms. If the aneurysm ruptures
sudden bleeding and potential brain damage may occur.
There are three
types of aneurysms may form --- saccular, saccular with a broad
base, or fusiform shaped structures that look like a diffuse bulging
of the vessel wall. The saccular aneurysm is a balloon-like
expansion or “sac” with a long thin stem that connects it to the
artery (Fig.1) that is eliminated by placing an aneurysm clip across
the neck (Fig.2). The “saccular with a broad base” shaped aneurysm
is similar in appearance to the saccular aneurysm, but has a thick
arm connecting it to the main artery. A fusiform aneurysm is more of
a misshapen bulge that distends the circumference of the
artery.
Figure 1
Figure 2
Other causes of
cerebral aneurysms are trauma (Fig.3) and infection --- both weaken
the blood vessel and allow the formation of an aneurysm.
Figure 3
What are the symptoms of a
cerebral aneurysm? Once the
aneurysm bursts or ruptures, the blood enters the brain and can
cause:
- Severe headache
- Nausea/vomiting
- Double vision or
sensitivity to light
- Neck pain or
stiffness
- Weakness
- Memory loss
- Paralysis
- Coma
- Death
What Complications are
associated with cerebral aneurysm? An aneurysm may produce different problems:
1. Subarachnoid Hemorrhage- Bleeding from ruptured blood vessels that occurs within the subarachnoid space.
The subarachnoid space is used to conduct cerebral spinal fluid (CSF) to all of the areas of the brain that need the essential
nutrients found in CSF. Once blood enters the subarachnoid space it prevents the CSF from circulating normally and can cause Hydrocephalus.
(See Hydrocephalus)Brain
tissue damaged by the bleeding may cause coma, paralysis of an arm
and/or leg on the side opposite the bleeding aneurysm, and
death.
2. Vasospasm- Chemicals and other active
substances released in a subarachnoid hemorrhage may cause blood
vessels to narrow producing a reduction in blood flow and oxygen to
the brain. This condition, known as vasospasm can make neurologic
symptoms worse and even precipitate a “stroke”.
3. Ischemia- Reduced blood flow. This can
cause brain damage to areas of the brain that do not receive enough
blood to function normally. Associated with vasospasm.
4. Rebleeding- Bleeding caused by the initial
rupture of the aneurysm is often stopped by the formation of a blood
clot that seals off the ruptured area. Rebleeding occurs when the
seal in the wall of the aneurysm, the blood clot, is broken free by
hypertension or the blood clot is reabsorbed.
5. Hematomas – The released blood from the
aneurysm can collect and form a hematoma. Hematomas may be without
symptoms or cause intracranial pressure increases that result in
further brain damage. Cerebral aneurysm is the leading cause of
non-traumatic intracranial hematoma. The two types of hematomas that
may form in response to a ruptured aneurysm are:
1. Subdural hematoma - Develops when aneurysm bleeding occurs in the arachnoid space (below the dura) and collects as a blood clot.(See Subdural Hematoma).
2.
Intracerebral hematoma - Develops when aneurysm bleeding occurs within the brain tissue.(See Intracerebral Hematoma)
Medical
Management Medical measures are
used in conjunction with surgical treatment when necessary, to
stabilize the patient before, during, and after surgery. One common
treatment associated with cerebral aneurysm is hypervolemia
(altering blood pressure) to reduce risk of vasospasm by
administering phenylephrine, dopamine or dolbutamine infusions which
elevate blood pressure to increase blood flow and oxygen to the
brain. One disadvantage to this strategy is the increased risk of
rebleeding. Anticonvulsants may be given to prevent epileptic
seizures. Osmotic agents and/or diuretics may be given in an effort
to treat increased brain pressures. Mechanical respirators are often
used to assist respiration and control both carbon dioxide and
oxygen.
Surgical
Treatment It is recognized that
if a patient is diagnosed with cerebral aneurysm, surgery is the
necessary course of action as soon as the patient is stable. The
stability or “grade” of a patient is based on his/her level of
consciousness. Early treatment is typically recommended, (preferably
within 72 hours of when the rupture occurs) if the patient is in
good condition and there is not significant evidence of vasospasm
shown in the angiogram (a test that measures blood flow in the
arteries). Early treatment cuts down the risk of vasospasm and
rebleeding. Late treatment is recommended when the patient needs
more time to recover and stabilize before surgery, or if there is
evidence of vasospasm in the arteries.
The most crucial
determining factor in the operation is the individual patient’s
health. A variety of tests are used to examine the patient’s overall
condition and identify any special considerations that would inhibit
the success of surgery. The pre-operative testing also allows the
surgeon to pin-point the size, location and shape of the aneurysm to
prepare the operating team for which technique will be most
effective. The characteristics of the aneurysm dictate how it is
treated.
Most often, a metal
clip is used to close the aneurysm off from the main artery by
clamping it around the stem or base of the aneurysm. If the aneurysm
is fusiform, it may be necessary to close off the entire artery to
prevent bleeding.
A newer method of
treatment involves placing a small catheter in the inguinal area,
moving it up into the arteries of the brain, and then eliminating
the aneurysm by using a stent (small tube to block blood flow to the
aneurysm) or small balloon to fill and eliminate the aneurysm
sac.
The Recovery Process is a combination of
the patient’s positive attitude, support of family, friends and a
regimented rehabilitation program. Depending on the extent of damage
caused by the aneurysm, the recovery process will vary. Some will
need extensive therapy to rebuild reasoning and motor skills, while
others will be able to return to daily activities shortly after
surgery.
It is a common
post-operative occurrence for the patient to experience a dull
headache. Nutrition is always very important to the recovery
process, and in the early stages of recovery, an all-liquid diet may
be administered. As the patient shows improvement the amount of
liquids will increase and eventually progress to a normal diet.
Immediately following surgery it is normal for the patient to
experience a period of depression and tiredness.
Upon discharge from
the hospital it is decided what course of action the patient should
take to maximize recovery. The recovery process can be a long one
and it is not always easy. It is common for the patient to
experience fluctuating emotions as he/she readjusts to daily life.
Cognative therapy and speech therapy may be combined with physical
therapy for those patients who sustain major brain injury from the
aneurysmal rupture. During this period it is essential that the
patient focus on incremental goals and recognize when progress is
being
made.
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