This information material has been designed to introduce you to the
category of brain problems called "aneurysms." Although some of this
subject matter may appear to be detailed and technical, we have made
every effort to explain (in parentheses, like this) what the terms
mean. In addition, your first review of this may be a little
frightening, particularly when you begin to recognize how very
serious and dangerous these problems are. However, it has been our
experience that patients and their families much prefer to have as
much factual information as possible in order for them to make an
intelligent decision about their choice of treatment. There is
nothing quite as terrifying as the "unknown." Our imaginations can
conjure many frightening things which usually are not at all
reflective of the situation. How many times have we thought or heard
the statement, "The problem must be terrible. The doctor hasn't
told me anything."
Our experiences with patients and their families have taught us many
things. An important lesson has been that their anxiety diminishes
considerably once they are armed with enough knowledge about the
particular problem, no matter how serious it is. They are also more
at ease knowing that the physician will take time to explain the
details to THEIR satisfaction and to answer their questions in terms
they can understand.
There have been major advances in neurosciences in the past 10 years.
Many of these advances have significantly contributed to a brighter
outlook for the patient with an intracranial aneurysm. The newer
microvascular neurosurgical techniques as well as the minimally
invasive endovascular treatments have played an important role in
these advances. The role of neuro-radiology in identifying, more
precisely, the anatomy of the brain circulation, together with
advanced intensive care unit medical management techniques for the
very ill, pre-treatment aneurysm patient (or post-treatment patient),
have been very helpful to improve the outcome for these patients'
recovery. Advances in anesthetic techniques for the delicate
micro-neurosurgical treatments have also contributed a great deal to
the better results.
In this paper I will try to explain the natural history of aneurysms.
That is to say: what they are, why they occur, where they occur,
and what you can expect if they are left alone. I will try to
review what it takes to evaluate these problems and why a combination
of medical and interventional (endovascular and surgical) methods
is usually recommended. I will review the treatment alternatives
together with their risks and limitations. There are always choices
in treatment. I grant to you that some of the treatments are poor
choices and most people with any common sense will not suggest or
request them; nevertheless, there are also some legitimate
alternatives in some cases.
Undoubtedly this printed material will not answer every question
for every patient or family member. I hope that you will accept
it as general background information on the subject. Please feel
free to take notes and ask whatever questions you wish. No two
patients or their problems are exactly alike. It is important that
you understand as much as you can. Our staff will be pleased to
help you in any way that we can.
Aneurysms that occur inside the head (intracranial) are among the very
serious neurological conditions which can cause severe brain injury
or death as a result of hemorrhage. Aneurysms are usually described
as weak places on the arteries, which supply blood to the brain.
They form in a manner that looks like a blister. They are similar,
in concept, to the weak spot on an inner tube of a car tire or a
child's balloon that is over-inflated.
Aneurysms are present in approximately five percent (5%) of the general
population. Although they can occur in children, they are more likely
to make their presence known in adults between 40 and 60 years.
Aneurysms form in particular areas of the cerebral (brain) arteries.
These are mostly where the arteries branch. Some of us are born with
a very small defect in an elastic membrane which is part of the thick,
middle layer of our brain arteries. As a result of the blood pounding
on the inside of the artery with each heartbeat, a small internal
hernia occurs through the weak and defective elastic membrane. Over
the years this internal hernia slowly enlarges to extend outside the
wall of the artery and takes on the appearance of a thin-walled
blister. (See Figures 1 and 2.)
The arteries of our brain have three layers. The outer layer is very
thin (called the adventitia). The inner layer is also very thin
(called the endothelium). The middle layer (media) is relatively
thick and is made mostly of muscle. Near the center of the media is
the elastic membrane (internal elastic membrane). Defects in the
internal elastic membrane are more likely to occur where arteries
branch. It is through this defect that the hernia of the inner wall
of the artery may occur. When the hernia extends through the entire
wall of the artery and forms a blister, a true aneurysm has formed.
Unfortunately the aneurysm wall is made up almost entirely of the
thin, inner and outer layers of the arterial wall and does not have
the protection of the thick muscle or its elastic membrane to keep
the blood from bursting out of the inside of the blood vessel.
Aneurysms represent one of the most serious causes of stroke.
Hemorrhage from a rupture of the aneurysm is the occurrence, which
we fear the most. The hemorrhage may be a small leak or a more
catastrophic bleed, which severely damages or destroys brain tissue.
Once a hemorrhage from an aneurysm occurs, 35% of these patients will
die no matter what treatment is given. This is in addition to those
patients who survive the initial hemorrhage but who have permanent
brain injury as a result of the hemorrhage.
It is very important to recognize that not all patients with one or
more aneurysms will have problems from the aneurysm. Aneurysms are
very unpredictable peculiarities. It is generally agreed that, in
any population of 100,000 patients who already have aneurysms, only
about 20 of these patients will experience a hemorrhage each year.
Of these 20 people, thirty-five percent will die as a consequence.
In those patients who suffer a hemorrhage and survive that experience,
there are certain statistical factors, which are recognized and are
important to know. Although subarachnoid hemorrhage (SAH) comprises
only 1% to 7% of all "strokes" (intracranial vascular accidents),
the loss of years of productive life for these patients is comparable
to "cerebral infarction" (death of brain tissue as a result of an
obstructed blood supply, as often occurs in older people) because
of the relatively younger age of the aneurysm patinet and the
generally poor neurological outcome for many of these patients.
Once an aneurysm has hemorrhaged, it is likely to do so again. The
patient who suffers an initial hemorrhage is at serious risk to
suffer another hemorrhage within 48 hours and again at approximately
two weeks after the first hemorrhage. The risk to life (mortality)
is greater with each subsequent hemorrhage, as is the risk to more
brain injury. In the event that the patient survives one month from
the first hemorrhage without a recurrence, there is about an 80%
chance they will survive to one year without treating the aneurysm.
Long-term survival of patients who have recovered from a ruptured
aneurysm (that is not permanently treated) is significantly lower
than that of the general population. It appears that there is a
little greater than 2% risk per year that the aneurysm will re-bleed
in the first 10 years after the initial hemorrhage. (Approximately
11.5% will have re-bled at five years, 21% will have re-bled at
10 years and 30% will have re-bled at 20 years after the initial
hemorrhage.) There is approximately a 3 1/2% risk to death per
year for those patients who survive the first hemorrhage and do
not undergo surgical treatment. The bleeding episodes are reported
to be fatal in 78% of patients. The overall mortality rates for
patients surviving the initial hemorrhage are 18% at five years,
31% at 10 years, and 45% at 20 years. (That is to say, 18% will
have died at a point five years after the initial hemorrhage; 31%
will have died at 10 years and 45% at 20 years.) These deaths
would be related to a recurrent hemorrhage.
Approximately 15% of aneurysm patients have two or more aneurysms
inside their head. There are certain factors, which help the
experienced physician determine which of the aneurysms has been
the one that hemorrhaged. Sometimes this is a difficult determination
to make. In any patient who has more than one aneurysm, the
unruptured one still represents a significant potential threat.
There is about a 10% risk to death within 10 years from the unruptured
aneurysm. There are some factors, which increase the likelihood to
have more than one aneurysm. Patients who are under 55 years of age
and also suffer with hypertension are twice as likely to have
multiple aneurysms compared to patients who have normal blood pressure.
Females are more likely to have multiple aneurysms than males.
Women who are over age 60 and have one aneurysm are twice as likely
to have multiple aneurysms compared to men of similar age.
Increasing age and hypertension are two factors in women that
correlate with multiple aneurysms. There are certain locations of
aneurysms, which seem to have a predilection to having a similar
aneurysm on the opposite side. This is almost a mirror-like
distribution. These aneurysms are relatively uncommon.
One question that is frequently asked about intracranial (inside
the head) aneurysms concerns factors of heredity. The neurological
and neurosurgical literature on this subject suggests that, "There
are some families which have an inherited weakness of the cerebral
blood vessel wall which may predispose these individuals to
aneurysm formation." The occurrence has been suggested to be a
strongly inherited (autosomal dominant) pattern; however, only a
few families have been reported. It is suspected that the familial
incidence is higher than has been reported; nevertheless, the
actual likelihood of this problem occurring in your children is
extremely small. Where there appears to be a family history of
aneurysms screening methods are available for these other
There are certain unusual medical problems, which are closely related
to the formation of an intracranial aneurysm. Fortunately these
conditions are very uncommon. They are listed here only for the
sake of completeness and to illustrate the rarity. For those who
are interested in learning more about these conditions, further
information is available. These unusual conditions are:
Another question that is frequently asked relates to how a patient
would know if they had an aneurysm and if there are any warning signs
prior to a hemorrhage.
- Coarctation (narrowing) of the aorta associated with
intracranial aneurysms in younger individuals including children.
- Polycystic disease of kidneys When this is associated
with the adult form (bilateral disease), 16% of these patients will
have an intracranial aneurysm.
- Fibromuscular disease of the renal and carotid arteries,
Marfan's syndrome, pseudoxanthoma elasticum, Ehlers-Danlos syndrome,
and Moya Moya disease are all diseases of connective tissue or
blood vessels and are associated with increased risks for intracranial
Almost 60% of patients will have warning signs preceding a major
hemorrhage. The interval between the last warning sign and a
hemorrhage averages between 6 and 17 days depending on the location
of the aneurysm. The likelihood of having a warning sign varies with
the location of the aneurysm in the cerebral circulation. A serious
change in the pattern of headaches or the onset of persistent
headaches in someone who rarely is bothered by headaches can be
important. The development of any of the following problems could
be warning signs of an aneurysm: drooping eyelid; double vision;
unilateral (one-sided) dilated pupil; blurred or absent vision;
temporary weakness (decreased motor power); impairment of peripheral
vision; speech disturbance; temporary deafness; and ringing in an ear.
All of these conditions could be due to the growth in size of the
aneurysm, which then compresses and injures an adjacent cranial
nerve or brain area. The onset of seizures (epilepsy) in someone
who has not had seizures previously is very important and should
be evaluated by someone knowledgeable in these matters.
There is another way that aneurysms are now coming to our attention.
There is an increasing frequency of "incidental aneurysms." This
term refers to the fact that the aneurysm has not yet either
hemorrhaged or caused any other difficulties. The presence of the
aneurysm is usually identified on one of the newer "brain scan"
techniques. For example, your physician may request a CAT
(computerized axial tomogram) or MRI (magnetic resonance imaging)
scan either to investigate a possible blood clot after a head
injury or for some other problem. These scans may "incidentally"
identify an aneurysm. Scans that are being done to investigate
the complaint of headaches may uncover an aneurysm, which may or
may not have anything to do with the cause of headaches.
Aneurysms can only be fully evaluated by a radiological (X-ray)
investigation called an angiogram or arteriogram. This test allows
us to evaluate all of the arteries of the brain (as well as the
blood circulation pattern of the brain including the veins). The
neurosurgeon will want to see several different views of the
aneurysm and its relationship to the nearby and directly adjacent
vessels. This test will also help to identify if any other
aneurysms or other cerebral blood vessel problems are also present.
Angiograms are usually performed by a neuroradiologist. This
physician has special training and competence to conduct these
investigations. Although these tests carry with them some risks,
they are small compared to the benefits gained for the patient. In
the hands of a competent neuroradiologist, the actual risk rates
are very small. The neuroradiologist will discuss these tests in
considerable detail with you and answer your questions.
(See Figure 6.)
A relatively new technique has emerged using Magnetic Resonance
Imaging (MRI) technology called Magnetic Resonance Angiography (MRA).
At the present time it may be used as a primary method for
"screening" patients who are suspected of having some intracranial
(inside the head) problem with the blood vessels to or of the brain.
MRA is still not sufficiently accurate in clear anatomical detail
for most patients to avoid cerebral angiography in those patients
who are surgical candidates. The same can be said about an even
newer method called "CT Angiography".
In actuality there is a team of physicians (neurosurgeons,
neurologists, neuro-radiologists, neuro-ophthalmologists, intensive
care specialists, etc.), surgeons and nursing staff as well as
other health care professionals (such as speech therapists, physical
and occupational therapists, neurophysiologists, etc.) who are
involved to varying degrees in the care of aneurysm patients.
Depending on the individual needs of the particular patient, these
neuroscience staff personnel will contribute to that patient's
The blood supply to the brain is mainly from four (4) major arteries.
The two CAROTID ARTERIES supply the front (anterior) circulation
to the right and left cerebral hemispheres. (See Figures 3, 4, and 5.)
The circulation to the back (posterior) of the brain is from the
two VERTEBRAL ARTERIES. After the carotid artery enters the head,
it branches into two (2) major divisions to supply the bulk of
the arterial blood to each cerebral hemisphere. These branches
are the ANTERIOR CEREBRAL (front brain) ARTERY and the MIDDLE
CEREBRAL (middle brain) ARTERY. Each of these arteries begins to
send off branch arteries immediately and continue to subdivide to
progressively smaller arteries in order to deliver the blood to
every area of the surface and interior of the brain. Each half
of the brain (each hemisphere) has its own Carotid, Anterior
Cerebral, and Middle Cerebral Arteries. Therefore, there are LEFT
and RIGHT CAROTID, MIDDLE CEREBRAL, and ANTERIOR CEREBRAL arteries.
The back (posterior) brain circulation comes from the two VERTEBRAL
arteries which join each other inside the head to form the very
important BASILAR ARTERY. This vessel, in turn, sends numerous small
and several important large vessels to the brain stem (medulla, pons,
and midbrain) and cerebellum (the balance and motor coordination
center of the brain). The BASILAR Artery ends where it forms the
two (2) large POSTERIOR CEREBRAL (back of the brain) Arteries which
go to the back of the left and right cerebral hemispheres. These
posterior cerebral vessels supply the occipital lobes of the brain
which are responsible for our sense of SIGHT. (See Figure 10 for
the functional areas of the brain.)
At the base of the brain there is a remarkable interconnecting system
of these major arteries which allows communication between the
anterior (front) and posterior (back) circulation systems as well
as the right and left hemispheres' systems. This circular
interconnection of arteries is called the CIRCLE OF WILLIS. (It is
named for the anatomist who described it.) The Circle of Willis
is very important for a number of reasons. It allows the brain an
alternative way to keep blood flowing to every area even if one or
more of the major blood vessels (supplying blood to the brain) were
to shut down (such as may occur in atherosclerosis hardening
of the arteries).
The Circle of Willis may be very important in planning surgery for some
aneurysms since we may have to rely on it to provide a detour route for
an adequate blood supply in order to eradicate some aneurysms.
Unfortunately a "complete" Circle of Willis is present in only 40% of
patients. In the other 60%, there is some deficiency in part of the
"Circle." That does not mean that it is "BAD"; however, when the
surgeon is planning the approach to "clip" the aneurysm, it is often
important to know if an alternative route (detour) of blood supply
is available or not. Surgery can usually be done successfully in
spite of a deficiency in the "Circle"; nevertheless, it is best to
have as accurate a "road map" of the cerebral circulation as possible.
This information is only part of what is learned during the ANGIOGRAM
Intracranial aneurysms can occur on any of the arteries of the brain.
(See Figure 7.) However, there is a strong predilection to certain
locations. Most aneurysms occur in association with the larger
cerebral arteries and are in the region of the base (underneath)
portion of the brain. Ninety percent (90%) of all intracranial
aneurysms occur in the front circulation (Carotid, Anterior and
Middle Cerebral Arteries) while ten percent (10%) involve the back
circulation (Vertebral, Basilar, and Posterior Cerebral Arteries).
In the anterior (front) circulation approximately 25% of aneurysms
involve the Internal Carotid Artery while 30% involve the Anterior
Cerebral Artery and another 30% involve the Middle Cerebral Artery.
The remaining 10-15% of anterior circulation aneurysms involve some
of the smaller branches of each of these major vessels.
In the posterior circulation system most of the aneurysms involve
the BASILAR ARTERY, usually near the area where the left and right
Posterior Cerebral Arteries originate. However, aneurysms can occur
anywhere along the Basilar Artery and may involve or incorporate (in
the aneurysm) vital blood vessels which nourish the brain stem. (In
the event that this unusual problem is encountered, it will be
discussed in more detail with you.)
We hope that the foregoing gives you a little better understanding
and appreciation for the requirement of a detailed "road map" which
a high-quality angiogram will hopefully provide. Each aneurysm
(in each patient) is unique to that patient. Each aneurysm in each
location has its own particular risks and technical problems relating
to surgery. High-quality, high-resolution angiography plays a vital
role in identifying important anatomy so that the surgeon is given
as much information as possible. While it is very uncommon for us
to be surprised, it could happen. We make every effort to obtain
the appropriate information so as to reduce the risks to the patient.
In medicine, there are usually some reasonable choices in the care
of most diseases. Sometimes the treatments carry with them more
risk than the disease itself. In diseases which themselves are
very serious, the treatments are frequently also quite serious.
That does not mean that the treatments cannot be or are not successful,
but it does clearly mean that there are certain risks to not achieving
a "perfect" result or to failure of the treatment. One must weigh
all the factors involved in the particular patient such as the
neurological condition, medical conditions that might interfere with
successful treatment, as well as the actual disease and its risks
together with the risks of the treatment, in deciding what the
best treatment method is for that patient. The experience and
capabilities of the physicians and surgeons in the treatment
methods are also important factors. The "ideal" treatment result
is the COMPLETE OBLITERATION OF THE ANEURYSM so as to prevent
another haemorrhage. There are some options; however, all of these
require some form of "invasive" intervention.
The "medical" management of aneurysms is an important treatment method
(even for the surgical candidate) in the initial phases of therapy
for the patient who has suffered a hemorrhage. Once an aneurysm
ruptures, it usually causes an intense brain reaction. The brain
becomes swollen, softer, and is reddened. A softened, swollen brain
is at more risk to injury if it is touched than under its more normal,
non-inflamed state. Many surgeons prefer to wait until the softening,
swelling, and inflammation subside before operating. During this
waiting period, there is a risk that the aneurysm will rupture again.
It is, therefore, very important to try to reduce the risks of another
hemorrhage (whether or not the patient is an operative candidate).
This initial phase of treatment requires the control of blood pressure
(with appropriate medication including sedation), control of headache
(which can be quite severe after the hemorrhage) together with
maintaining adequate nutrition and dealing with any other medical
problems that might exist are important factors with early stages of
treatment. In order to prevent sudden changes (particularly elevation)
in blood pressure, it is important to reduce the patient's anxiety
level, pain, and sudden straining. Depending on the psychological
make-up of the patient and their level of agitation (sometimes
caused by the intense pain), higher levels of sedation and analgesics
(pain relievers) may be necessary.
In order to reduce the chances of the patient becoming concerned
with other events, we usually avoid their access to television,
newspapers or the internet. (They don't need any other bad news
or shocks in response to world or regional events). Patients who
suffer intracranial hemorrhages are often bothered by light. We
usually place them in a darkened room for this initial part of
treatment (which may last up to two weeks and, under rare
circumstances, as long as one month). While they are not kept
entirely asleep, we strive to keep them moderately tranquil and
comfortable. We ask family and friends to restrict their visits
to a short time and provide loving support and encouragement while
avoiding issues that may be upsetting to the patient.
There are no medications that can cure aneurysms. Additionally,
there are no medications that can prevent bleeding from the aneurysm
on a long-term basis. However; we have long used an anti-fibrinolytic
agent, delivered intravenously, from early on once we identify
that the cause of the haemorrhage has been from an aneurysm. This
medication acts to prevent the clot that has formed on the outside
of the aneurysm from breaking up. It is this clot that is acting
to prevent another haemorrhage. Unfortunately, this medication
cannot be used for extended periods of time. (Please see the last
paragraph on this page for additional information about this.)
If, for some reason (which would certainly constitute a very rare
circumstance), interventional therapies are not going to be done,
then it is probably best to remain at bed rest with blood pressure
well controlled for one month. This will allow some time for scar
tissue to form over the part of the aneurysm where the leak occurred.
After that, the treatment consists mostly of controlling blood
pressure and avoiding sudden, severe changes in intracranial
pressure (as can happen with sustained straining in a constipated
individual). There are no other therapies, medications, or
non-surgical procedures which are available (except as discussed
in the following sections). That does not mean that all patients
who have aneurysms or all patients who have had a hemorrhage from
an aneurysm are doomed. We ask you to review the preceding section
on the "Natural History." The discussion of the risks involved
permits us to use the information as a guideline in helping to
make medical management decisions. There is no way to predict
with certainty what will happen to each individual patient. There
is also no doubt that, once an aneurysm has hemorrhaged, the patient
is under an increased risk for another hemorrhage and that the life
expectancy is shortened by virtue of the definite increased death
rates associated with untreated aneurysms. However, there are
patients who do survive without having surgery.
A recent medical literature review regarding this aspect of
treatment (ADVANCES IN SUBARACHNOID HAEMORRHAGE, Feigin, V.L.
and Findlay, M.) appeared in STROKE 37: 305-308, 2006
emphasizes that : "Medical treatment of patients with aneurysmal SAH
[subarachnoid haemorrhage] is directed toward the prevention and
management of neurological (e.g., aneurysm rebleeding,
hydrocephalus, cerebral vasospasm and ischemia [decreased blood
supply] and seizures) and systemic complications (e.g.,
hyponatremia [low sodium], cardiac arrhythmia and myocardial
damage and neurogenic pulmonary edema [lung problems].)"
One factor that seems important is the early use of an agent that
prevents a clot ("antifibrinolytic" agent) from breaking up. This
article emphasizes that "A recent randomized trial showed that
immediate administration of antifibrinolytic agent tranexamic
acid (1 gram IV, followed by 1 gram every 6 hours until aneurysm
repair carried out as soon as possible) reduced the rate of
devastating early aneurysm rebleeding from 11% to 2.4%. Short-term
antifibrinolytic treatment may protect from acute aneurysm
rebleeding, but long-term antifibrinolytic treatment in patients
in whom late aneurysm repair is planned does not improve overall
outcome because the reduction in the rate of rebleeding before
delayed surgery is offset by an increase in poor outcome
secondary to cerebral ischemia."
There are some very important newer Minimally Invasive
techniques for treating patients with aneurysms. These are
techniques conducted by specially trained Interventional
Neuroradiologists. The procedures consist of inserting a length
of platinum, copper-beryllium (or other specially designed) wire
via angiography into the aneurysm to try to induce clot formation.
Another Endovascular angiographic technique involves the
placement of a permanent balloon inside the aneurysm or the mouth
of the aneurysm to try to stop blood from flowing to the aneurysm.
As these endovascular angiographic interventional methods have evolved,
it has become safer and more appropriate to utilize these techniques in
select circumstances. This methodology has become the most appropriate
treatment for many aneurysms in recent years. Unfortunately, some
aneurysms do not lend themselves to this treatment for any of
several reasons but mostly related to size and configuration. Oftentimes,
once an aneurysm is determined to be amenable to endovascular
interventional techniques, this treatment may be done at the time of
or shortly after the diagnostic angiographic procedure is done.
A recent review by the respected Cochrane Project and reported
in the "Cochrane Corner" (published in STROKE 2006; 37:572-573)
concludes that "for patients in good clinical condition with ruptured
aneurysms of either the anterior or posterior circulation, we have
firm evidence that if the aneurysm is considered suitable for surgical
clipping and endovascular treatment, coiling is associated with a
better outcome." Furthermore the report states: "For patients in poor
clinical grades, there is no reliable randomized evidence comparing
the risks and benefits of coiling versus clipping. Because coiling
is less invasive than surgery, also in patients with poor clinical
condition, coiling seems the preferred option. A disadvantage of
coiling is that aneurysms are more often incompletely treated (90%-100%)
obliteration) and carry a risk for reopening. The long-term follow-up
(>1 year after SAH) of coiled patients, with regard to renewed filling
of the aneurysm, is an unknown but important issue that needs further
study." (Note: SAH=Subarachnoid Haemorrhage)
The technologies underlying these endovascular procedures are still
evolving. Among the problematic issues for any form of aneurysm
treatment are the concerns for re-bleeding. In the case of endovascular
treatment, rebleeding can occur despite the apparent excellent
placement of the "coils". A recent Editorial in STROKE
(Gary J. Redekop, MD; 2006; 37:1252-1353) summarized an important
scientific investigation regarding aneurysm treatments. "The
International Subarachnoid Aneurysm Trial (ISAT) compared
microsurgical clipping and endovascular coil occlusion in patients
with ruptured aneurysms felt to be suitable for either technique.
This study showed that the risk of late re-bleeding was low but
more common after endovascular coiling than after clipping. There
are concerns about the long term durability of coil occlusion as
well as the need for follow-up imaging and further treatment if
aneurysm recurrence is detected."
Furthermore, this editorial commented that: "The Cerebral Artery
Rerupture After Treatment (CARAT) study compared rates of recurrent
haemorrhage in patients with ruptured aneurysms treated initially
with coil embolization or surgical clipping. Significantly more
patients treated with coiling required repeat treatment during
the first year and continued to require additional treatment,
although infrequently, as long as 5 years after the initial
procedure." This is a matter of considerable importance since
"serious morbidity occurred in 11% of patients undergoing repeat
coil embolization and 17% of those undergoing repeat surgery."
The durability of aneurysm coil embolization is thought to depend
on the "packing density" of the coils within the aneurysm. Part
of the reason for the apparent "failure" of coiling to maintain
complete obliteration of an aneurysm is the entity of "compaction"
of the coils over time. As the coils are pressed closer together,
they no longer completely fill the aneurysm. One of the newer
advances in coil technology involves the use of coils that are
coated with a hydrophilic polymer causing the coil to swell when
they come in contact with blood resulting in a more densely
packed aneurysm. (This technology was reported in STROKE:
2006; 37:1443-1450.) The point in sharing this information
with you is to demonstrate that, clearly, there are significant
advances that are being made in this field to improve the safety
of the procedures as well as ensure a better long term outcome
for these patients.
Specific treatment strategies must be individualized, taking
into account the patient’s age, neurological status and other
medical conditions as well as the specific anatomical
characteristics of the aneurysm. These characteristics of an
aneurysm that help to determine the most efficacious interventional
technique include its size, location, geometry, relationship to
the parent artery or other adjacent arteries, the size of the dome
and shape of the aneurysm neck, presence of calcification within
the wall of the aneurysm and the presence of clot (thrombus)
within the aneurysm. A multi-disciplinary team that emphasizes
an honest and unbiased collaboration between the surgeons and the
interventionalists is critical in the decision making process for
the successful treatment of these patients.
There are some circumstances that occur which will result in a
recommendation for early surgical treatment. In these cases, the
operation is usually carried out within the first forty-eight (48)
hours after the initial hemorrhage. We are trying, in these
situations, to reduce the risks to life related to repeat
hemorrhage by obliterating the aneurysm before it can do harm
again. However, there are some additional risks to this "early
surgery". There is a significant likelihood that "vasospasm"
(spasm or narrowing of the blood vessels of the brain) will occur
in the "early" operations. (See Page 15, Part 2, for further
discussion of vasospasm.) However, one additional major advantage
to the early clipping of the aneurysm is that, in the event that
vasospasm occurs, we can "artificially" raise the blood pressure
with medications and try to "drive" blood through the narrowed
arteries. Obviously this technique of raising blood pressure
could not be used to treat vasospasm unless the aneurysm
was already clipped since raised blood pressure would be expected
to cause a hemorrhage from an unclipped aneurysm. Another possible
technique to overcome "focal" spasm is through another
angiographic maneuver called "balloon angioplasty". In this
instance, a balloon catheter is used to "dilate" the segment of
a vessel that is in spasm. (This can ONLY be done AFTER the
aneurysm has been surgically "clipped".) This is another example
of the advances available using interventional neuroradiology
For most patients with an intracranial aneurysm (most particularly
those who have already suffered a hemorrhage), the treatment of
choice is to obliterate or occlude the aneurysm. The goal of these
interventions is to stop blood from going into the aneurysm
while preserving the blood supply to the brain. The endovascular
interventional techniques were described previously. The surgical
method to accomplish this results in applying a specially
designed metallic "aneurysm clip" in such a way that isolates
the aneurysm from the artery. When blood can no longer get into
the aneurysm (the weak spot), then it can no longer hemorrhage.
The clip is permanent (See Figure 8). The remainder of the
aneurysm wall beyond the clip shrivels up and usually scars.
Occasionally we must use more than one clip to successfully
occlude the aneurysm. There are some aneurysms which actually
have to be cut out and the blood vessel sewn up. This is more
hazardous and is rarely required. Other unusual aneurysms cannot
be completely clipped (usually because to clip them entirely would
result in the sacrifice or injury to another important artery and
thus produce a stroke). In the event that only part of the aneurysm
can be clipped, the surgeon will attempt to reinforce the remaining
segment of aneurysm in some fashion (usually with a rapidly setting
Although the ideal method (to permanently stop all blood flow to
the entire aneurysm) is usually accomplished, it is not always
possible to achieve the ideal. In these cases, we strive to
reinforce the wall to provide a stronger wall for the part of
the aneurysm that remains. In some unusual cases, surgery cannot
be completely or even partially accomplished. Sometimes we find
that the clipping of the aneurysm (or coating it with glue to
reinforce the weak blood vessel wall) would have a high risk to
produce a profound neurological injury or death. In these rare
cases (and those where surgery is not being done), the patient
assumes the risks of the natural history of the disease.
Regrettably, physicians cannot cure everyone and even modern
treatments are not always completely successful.
In some even more unusual circumstances, the only way to deal
with the aneurysm is by stopping the blood flow in the major
artery or arteries. Obviously this could also stop the blood
supply to part of the brain. It is in these cases that the
presence of the "Circle of Willis" collateral blood supply may
be particularly important. These patients may require an
additional operation which brings a new "bypass" artery to try
to ensure and adequate blood supply. These situations are
uncommon and will be discussed in more detail when the
particular situation arises. There are additional medical
literature references relating to this technique such as
Microsurgical Cerebral Revascularization: Concepts and Practice.
Surgical Neurology 1:355-359, 1973 (Lazar, M.L. and Clark, W.K.)
and Selective Cerebral Revascularization as an Adjunct in the
Treatment of Giant Anterior Circulation Aneurysms Neurosurgical
Focus 14(3): Article 4, 2003 (Brian A. O. Shaughnessy, M.D.,
Sean A. Salehi, M.D., Stefan A. Mindea, M.D., H. Hunt Batjer,
M.D.) among others that are more recent, all attesting to the
potential usefulness of this approach.
All of the operations directed towards aneurysms require making an
opening or window in the bony skull. The medical term for this
operation is a "craniotomy". In most cases, the bone will be
replaced, and it is held in place so that it will not move. These
are almost invariably quite acceptable from a cosmetic standpoint
as well. Each operation directed towards a specific aneurysm has
specific risks depending upon the precise location of the aneurysm
as well as the age and medical, as well as neurological, condition
of the patient. In general, all operations carry with them a
certain element of risk to life. These operations are conducted
under general anesthesia. The anesthesiologists are experienced
in these neuro-anesthetic techniques and will discuss the anesthetic
aspects with you. The risk to life from the general anesthetic,
is fortunately, very small. In the case of a previous hemorrhage
from the aneurysm, the risk to life is generally considered to be
higher compared to the surgical risk to a patient whose aneurysm
has not ruptured.
The projected mortality rate for craniotomy for unruptured aneurysms
is 1% or less. The mortality rates for patients with ruptured
aneurysms depend on several factors which include the presence or
absence of lung and heart problems (or any other major medical
conditions) as well as the neurological condition of the patient.
As a general rule, mortality rates are higher for patients whose
neurological condition is worse. Nevertheless, the overall
mortality rate for patients who have had ruptured aneurysms is
still relatively small compared to the natural history of the
disease. The projected mortality for many patients who have had
ruptured aneurysms is between 3 and 5%. Certain aneurysms in
certain locations carry with them higher risks than other
locations. These will be discussed on an individual basis
relating to the specific aneurysm involved in each patient.
Advances in microvascular neurosurgical technique have been of
particular benefit for aneurysm patients. The risks to life and to
neurological injury have significantly decreased in recent years.
Nevertheless, there are some risks to injury to adjacent anatomical
structures. If the aneurysm is adjacent to, pressing on, or
involving any of the visual sensory apparatus (such as the optic
nerve, optic chiasm, or optic tract), then there is risk to
impairment or loss of vision. In the event that the aneurysm is
pressing on the nerves that supply the muscles, which work the
eyelid or move the eyeball, then there is a risk to injury to
these nerves with the resulting drooping eyelid and/or double
Aneurysms which are underneath the front portion of the brain
(such as anterior communicating or anterior cerebral artery
aneurysms) are directly adjacent to and frequently involve the
area of brain, which controls some aspects of personality.
Personality alteration can occur as a consequence of the initial
rupture of these aneurysms or of the surgical procedures aimed
at their repair. Fortunately, this has been uncommon in our
We are confident that you are aware that the right side of the
brain controls the left side of the body and that the left
side of the brain controls the right side of the body. Surgery
upon an intracranial aneurysm carries with it a risk to injury
to the blood vessels from which they arise and to which they
have an intimate relationship. Blood vessel injury could result
in decreased blood flow to the brain potentially resulting in
paralysis of the face, arm and leg of the opposite side. For
surgical problems involving the left hemisphere (particularly
for left middle cerebral artery aneurysms and less commonly left
internal carotid artery aneurysms), there is the additional risk
to impairment of communication skills. The left hemisphere is
the dominant (by virtue of the fact that it contains the
communication control centers) hemisphere in almost all
right-handed people and in some left-handed people. In a similar
fashion, other aneurysms in other locations have risks to injury
to those particular areas of the brain. These will be discussed
on an individual basis.
One of the most serious complications of a ruptured aneurysm and
aneurysm surgery is the occurrence of VASOSPASM. This is a
condition resulting in the contraction of the wall of the blood
vessel producing a much narrower blood vessel. As a consequence,
the diameter of the blood vessel, through which the blood flows
to the brain, is much reduced. In some cases, it becomes so
severe that the blood supply to the brain is shut down.
Vasospasm is usually self-limiting and reversible; however,
severe neurological injury or death can occur as a consequence
of this terrible problem. Despite vigorous therapy, it is very
difficult, if not impossible, to treat in some patients. (Please
see the discussion of some therapeutic maneuvers for the treatment
of vasospasm on Page 12 & 13.)
Brain swelling is another potential risk of brain surgery.
Fortunately, this is much less common than in previous years.
Hemorrhage or blood clots very rarely are encountered as
complications of surgery in our experience. Infection is also
a very rare occurrence.
Modern aneurysm clips are very highly refined from a metallurgical
standpoint. Clip failures are exceptionally rare. In the past,
there have been reports of clips slipping from the aneurysm, and
at some later date postoperatively the patient is found to
have reformed the aneurysm. This has been an exceptionally
rare occurrence in our experience (having seen this in two
patients who were referred after another surgeon had operated
upon them previously). We have not had any aneurysms reform
that we are aware of. Although we have had the clip progressively
dislodge in some cases of very large aneurysms while the
operative procedure was being carried out, we are only aware
of a single instance where a clip has even slipped slightly
after surgery was completed. Nevertheless, a "slipped clip"
is a risk of this surgery. It is equally rare for us to carry
out an operative procedure and not be able to clip the
aneurysm; however, this is another serious, although fortunately
rare, risk of aneurysm surgery.
Most patients who have suffered a hemorrhage from an aneurysm
will already be in the Intensive Care Unit. All patients who
undergo craniotomy for aneurysm repair will be in the Intensive
Care Unit postoperatively for at least several days. Most patients
are awake and responding immediately after surgery. Most
patients are able to take some nourishment by mouth within 12
to 24 hours postoperative. Angiography is not routinely carried
out on every aneurysm patient postoperatively. Nevertheless,
there are some aneurysms or neurological conditions associated
with their repair for which we will request postoperative
The long-term follow-up for postoperative patients falls into
two main categories. Most patients who have undergone surgery
for anterior circulation (internal carotid, anterior cerebral
and middle cerebral arteries or their branches) aneurysms will
be taking medication to try to prevent seizures (epilepsy).
This is usually taken for the first two (2) postoperative years
provided there have not been any seizures. After two years,
the medication is progressively discontinued. In the event that
seizures occur after this then the medication will probably be
required on a permanent basis. Sometimes the seizures (either
pre-operatively or postoperatively) are difficult to control
and may require several medications.
In the weeks following discharge from hospital, the patients
are homebound. Their level of activity is, to a certain extent,
governed by their medical and neurological capabilities. All
postoperative patients are required to avoid bending, lifting,
pushing, pulling, or straining for at least three (3) months.
They are to avoid the use of aspirin-containing medications
(since the aspirin interferes with platelet function of the
blood and could result in bleeding) unless specifically
directed to do otherwise. The same is true for most
"anti-inflammatory" drugs (such as ibuprofen), which are also
used by many people as a "pain reliever". Walking around the
house or in the garden is all the exercise that is permitted
in the first pot-operative weeks. Most patients will be seen
in the office two (2) weeks after leaving the hospital. At
that time further instructions for activities (based on the
individual's condition) will be reviewed.
The majority of patients are required to begin walking outside
the house (with an accompanying adult) on a "progressively
increasing distance" schedule. As a general rule, (taking into
consideration any neurological or medical conditions) patients
should expect to increase the distance they walk each day or
every other day. We ask most of them to set a schedule that
will progressively lead them to walk a distance of one (1) mile
at a point 4 to 6 weeks postoperatively and two (2) miles when
they are 8 to 12 weeks postoperative. The patients should
avoid becoming overheated as well as over-tired.
Headache is rarely a long-term problem. Tylenol or a similar
non-narcotic agent is usually all that is required. If headaches
become a problem subsequently, further tests may be required.
One of the potential long-term complications of hemorrhages from
aneurysms or aneurysm-repair surgery is the development of
HYDROCEPHALUS. This complication is relatively uncommon, but
it is serious and may require further surgery (called a SHUNT
PROCEDURE). In this condition the cerebrospinal fluid (CSF),
which bathes and cushions the brain inside the skull, has
developed a problem. The cerebrospinal fluid is manufactured
in the interior brain cavities (called ventricles). The fluid
helps to nourish the brain and makes its way through the brain
in a series of channels and ventricles. Ultimately, the fluid
escapes the interior of the brain and surrounds the base and
then courses over the cerebral hemispheres. It is re-absorbed
into the blood stream through a special vein mechanism. Blood
from a ruptured aneurysm can obliterate the fluid's pathways
at the base of the brain or over the surface of the brain and
cause an obstruction to the flow of fluid and its absorption.
However, the brain keeps manufacturing the fluid in the ventricles.
Since it can no longer be absorbed at the rate it is being produced,
the pressure inside the ventricles progressively increases and
the ventricles become larger. (This is HYDROCEPHALUS: Hydro = water;
cephalus = brain.) The ventricles become like inflated balloons
inside the brain and can injure brain function. The condition
can occur acutely (soon after a hemorrhage from the aneurysm)
or years later as a result of a slowly progressive scarring in
the fluid absorption pathway (subarachnoid space) initiated by
the presence of blood from a hemorrhage years before or from
surgery. (See Figure 9.)
If hydrocephalus becomes a problem, a SHUNT PROCEDURE may be
required. This operation involves placing a silicon tube (with
a valve system) into the ventricle (through a small hole drilled
in the skull) and diverting the cerebrospinal fluid to another
area (the heart or abdominal cavity) to allow it to be absorbed.
This relieves the pressure from the interior of the brain.
Hydrocephalus is an INFREQUENT complication. However, it can
take many years to occur. This is only one of the reasons for
which patients are followed on a yearly basis after their
In the first year, routine follow-up evaluations are usually at
2 weeks postoperatively and then monthly for the first three (3)
months. After this, the visits are at six (6) months and twelve
(12) months postoperative. In the event that problems arise,
the patient will be seen whenever necessary.
The return to daily and work activities depends on the condition
of the patient and the work requirement. For most patients who
have sedentary jobs, they can anticipate returning on a
progressive basis (each week increasing the number of hours
worked) after 1 to 3 months postoperative. For patients who do
heavy work or have some neurological impairment, return to work
will be delayed.
As a general rule, the brain has the capability to recover from
injury. However, if brain cells have died, their functions can
NEVER recover. Whatever neurological injury is present at
a point one year after corrective aneurysm surgery can usually
be regarded as permanent. This means, of course, that RECOVERY is
possible (to some degree, if not completely) within the first year.
Where necessary and appropriate, Rehabilitation and Physical
Medicine Specialists will strive to achieve the maximum
recovery possible for those patients who need their services.
In those patients where endovascular coiling has been utilized,
follow-up cerebral angiography becomes an important part of their
ongoing management. Aneurysm "reformation" is a risk that is
well documented in patients having undergone endovascular coiling.
The only accurate way to determine this event is through formal
angiography. In those cases where the aneurysm has "reformed",
additionally coiling may become appropriate. (Please review
the discussion on Pages 11 & 12 of this section for more
information about this.)
Follow-up cerebral angiography is rarely required in patients
who have undergone successful surgical clipping of an aneurysm
since most surgeons definitively "prove" that the aneurysm has
been obliterated by either draining the aneurysm or removing
it once it has been clipped. This is done at the time of the
definitive clipping procedure in order to satisfy the surgeon
that the task has been completed without any doubt. There are
unusual cases where this cannot or should not be done. In those
instances, follow up angiography may be important.
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