A cerebral (brain or intracranial) aneurysm is an area where a
blood vessel in the brain weakens, resulting in a bulging or ballooning
out of part of the vessel wall. Usually, aneurysms develop at the point
where a blood vessel branches, because the “fork” is structurally more
vulnerable. The disorder may result from congenital defects or from
other conditions such as high blood pressure, atherosclerosis (the
build-up of fatty deposits in the arteries), and less commonly, head
trauma or infection.
Aneurysms are usually found at the base of the brain just inside
the skull, in an area called the subarachnoid space. In fact, 90 percent
of subarachnoid hemorrhages (SAHs) are attributed to ruptured cerebral
aneurysms and the two terms are often used synonymously.
in size, from quite small – about 1/8 inch – to nearly one inch.
Aneurysms larger than one inch are called giant aneurysms, pose a
particularly high risk, and are difficult to treat.
or "berry" aneurysms, which are shaped like a small sac, are the most
common type and often require intervention.
- Fusiform aneurysms
are diffuse bulges of the vessel wall involving most of the entire
circumference of the blood vessel itself. They may rupture or cause
stroke-like symptoms when they compress the surrounding brain.
aneurysms are rare and result from an infection. The infection damages
and weakens the blood vessel, thereby increasing the associated risk of
rupture. This infection occurs most commonly as a complication of
subacute bacterial endocarditis (a heart infection). Traumatic
aneurysms occur when a cerebral blood vessel incurs trauma from a head
injury. The damaged blood vessel weakens at the site of injury which may
cause it to rupture.
Prevalence and Incidence
year, an estimated 30,000 people in the United States experience a
ruptured cerebral aneurysm, and up to 6 percent of the population may be
living with an unruptured aneurysm.
- Worldwide statistics vary
greatly depending on the country and demographics, ranging from as low
as 5.1 cases per 100,000 persons to as high as 19.6 cases per 100,000
persons, based on age-adjusted incidence studies.
- About 40 to
50 percent of patients with ruptured aneurysms survive; 20 percent of
these patients will have no permanent physical deficits.
occurs in about 20 percent of cases within the first 14 days after the
- Aneurysms occur in all age groups, but the
incidence increases steadily for individuals ages 25 and older.
are most prevalent in people ages 50 to 60.
- Aneurysms are
about three times more prevalent in women.
- The presence of
multiple aneurysms or a family history of aneurysms increases risk.
Aneurysms — Celebrities
62, Actress (1985)
Laura Branigan, 47, Rock singer (2004)
Niekro, 61, Baseball player (2006)
Mike Royko, 65, Journalist (1997)
Sagapolutele, 39, Retired NFL player (2009)
Guy Williams, 65, Actor
Joseph Biden, U.S. Vice
Quincy Jones, Music Producer (in the 1970s)
Stone, Actress (2001)
Neil Young, Rock singer (April 2005)
- Hypertension (high blood pressure)
- Excessive alcohol
- Congenital (genetic) predisposition
or trauma to blood vessels
- Complication from some types of
who suffer a ruptured brain aneurysm may have warning signs, including:
- Nausea and vomiting
- Stiff neck
- Blurred or double vision
- Sensitivity to light
- Loss of sensation
Many people with
unruptured brain aneurysms have no symptoms. Others might experience
some or all of the following symptoms, which may be possible signs of an
- Cranial nerve palsy
- Dilated pupils
- Pain above and behind eye
- Localized headache
weakness or numbness
outcome for patients treated before a ruptured aneurysm is much better
than for those treated after, so the need for adequate evaluation of
patients suspected of having a cerebral aneurysm is very important.
Angiography (also called cerebral angiogram, carotid/vertebral
An angiogram provides accurate information that
cannot be obtained from other tests. It can help detect the location and
size of aneurysms and vascular malformations.
Arteries are not
normally seen in an x-ray, so contrast dye is utilized. The femoral
artery of the leg is usually used. A local anesthetic is administered,
the artery is punctured, and a needle is inserted into the artery. A
catheter (a long, narrow, flexible tube) is inserted through the needle
and into the artery. It is then threaded through the main vessels of the
abdomen and chest until it is properly positioned in the arteries of
the neck. This procedure is monitored by a fluoroscope (a special x-ray
that projects the images on a computer monitor). Contrast dye is then
injected into the neck area through the catheter, from where it flows to
the brain, and x-ray pictures of the head are taken. This procedure is
usually completed in less than an hour. Because the test is invasive,
cerebral angiography carries a measurable though small (0.5 percent)
risk of stroke. Cerebral angiography is considered the gold standard
test for evaluation of the blood vessels of the central nervous system.
Tomographic Angiography (CTA)
CTA is a radiological test that
combines the technology of a conventional CT scan with that of
traditional angiography to create detailed images of the blood vessels
in the brain in a noninvasive manner. This is performed by injecting a
volume of contrast agent, similar to that used in the conventional
angiogram, through a vein in the patient’s arm. Advantages of CTA
- Provides accurate identification of the exact
size, location and configuration of the lesion within minutes of SAH
- Patients do not need to be transferred to an
- No additional personnel are required
is no risk of ischemic stroke
The only risks from
undergoing this procedure are also associated with conventional
angiography: an allergic reaction to the dye and potential damage to the
kidneys caused by the dye. Although in most cases CTA will provide
important and accurate diagnostic information, it is less accurate and
less sensitive than cerebral angiography. This fact is particularly
important for small, blister-like aneurysms, or dissections (tears) of
blood vessels causing SAH.
Computed Tomography (CT or CAT
scan): A diagnostic image created after a computer reads x-rays. In
some cases, a medication will be injected through a vein to help
highlight brain structures. Bone, blood and brain tissue have very
different densities and can easily be distinguished on a CT scan. A CT
scan is a useful diagnostic test for hemorrhagic strokes because blood
can easily be seen. However, damage from an ischemic stroke may not be
revealed on a CT scan for several hours or days and the individual
arteries in the brain cannot be seen. CT perfusion (CTP) is augmented CT
that gives physiologic information about brain tissue that has been
injured, or may be suffering from insufficient blood flow, before the
stroke has ended. It is performed with CTA, and provides high-quality
diagnostic information about stroke and ischemia in about seven minutes.
CTA is the preferred diagnostic method if an aneurysm is suspected.
Ultrasound: A water-soluble gel is placed on the transducer (a
handheld device that directs the high-frequency sound waves to the
artery or vein being tested) and the skin over the veins of the
extremity being tested. There is a "swishing" sound on the Doppler if
the venous system is normal. Both the superficial and deep venous
systems are evaluated. This test may be used to monitor for vasospasm
after aneurysm surgery.
Magnetic Resonance Angiogram (MRA):
This is a noninvasive study which is conducted in a magnetic resonance
imager. The magnetic images are assembled by a computer to provide an
image of the arteries in the head and neck. The MRA shows the actual
blood vessels and can help detect blockage and aneurysms. MRA does not
provide more information about a cerebral aneurysm than a CTA of good
quality, and takes much longer to perform (about 35 minutes). It is also
contraindicated in patients with certain types of metallic implants.
Its advantages over CTA are that 1) patients with iodine allergy are not
excluded; 2) there is no exposure to ionizing radiation.
intracranial pressure, direct brain destruction
leak into the cerebrospinal fluid (CSF) or areas surrounding the brain
and cause an intracranial hematoma (a blood clot). Blood can irritate,
damage, or destroy nearby brain cells. This may cause problems with
bodily functions or mental skills. In more serious cases, the bleeding
may cause brain damage, paralysis or coma. The immediate effect of
aneurysm rupture is increased intracranial pressure, with immediate
death occurring in 20 to 30 percent of cases.
Brain Swelling (Edema)
like other areas of the body, has an angry response to injury. This
inflammatory response may greatly increase the mass effect of a
hemorrhage, and create severe conditions of brain swelling and
distortion in a delayed fashion (2 to 5 days). Because the skull is
closed, even small degrees of swelling may lead to significant increases
in intracranial pressure.
Delayed Cerebral Vasoconstriction
Blood leaking around the brain may cause
vasospasm, a narrowing of the blood vessels, which decreases the amount
of blood supplied to the brain, and may result in a stroke. Vasospasm
usually develops 5 to 8 days after the initial rupture, but the patient
is at risk for up to 21 days (most often 3 to 14 days after SAH, with
peak vasospasm occurring between days 7 to 10). To treat vasospasm,
blood pressure is often purposely elevated with medications. Another
procedure requires the use of tiny balloon catheters that are inserted
in a microcatheter through an artery, and then threaded into the
affected blood vessels. Once in place, a balloon is inflated to widen
the affected blood vessels and increase blood flow. Catheters can also
be used to administer medication directly, to help increase the flow of
blood. These procedures carry very high risk and are preferably used
after the aneurysm has been secured by either coiling or clipping.
vasospasm is not completely understood. It is the leading cause of
delayed death and neurological disability in patients initially
surviving the rupture of a cerebral aneurysm.
from a ruptured aneurysm can block CSF circulation, leading to
hydrocephalus, a condition in which excess CSF builds up within the
ventricles (fluid-containing cavities) of the brain. This may increase
pressure within the head. Fluid may also build up in the brain after
surgery to repair the aneurysm. To stop fluid from building up, a drain
may be placed in the ventricles, to remove excess CSF and blood that has
leaked. In cases where normal CSF circulation is not restored, a
permanent diversion called a shunt is surgically implemented. This is
necessary in about 50 percent of patients sustaining a high-grade SAH.
combined effect of these complications creates a 30-day mortality of 50
percent for this disease, regardless of the treatment used to eliminate
the aneurysm. Thus, the successful obliteration of the aneurysm is the
first key consideration in the patient’s treatment.
The treatment of an aneurysm, like all medical
decisions, should be agreed upon by both the physician and the patient.
If the case is a medical emergency, in which the ruptured aneurysm has
caused the patient to lose consciousness, this discussion may take place
with the patient’s nearest relative or medical decision maker. The
treating physician will discuss the risks and benefits of each available
treatment option. He or she will usually recommend one treatment over
another, based on the patient’s individual circumstances.
the best method of securing the aneurysm should be made on an individual
basis, in general, patients with a ruptured cerebral aneurysm should be
treated as soon as possible. Surgical risks and outcomes depend on
whether or not the aneurysm has ruptured, the size and location of the
aneurysm, and the patient's age and overall health.
factors should be considered:
- Risk of hemorrhage — what
is the chance of the aneurysm rupturing?
- Size, shape and
- Age and health of patient
- Family history
is considered a reasonable option if the aneurysm is very small or in a
location which is felt to present a low risk of growth or rupture.
Repeated testing over time may be recommended and the risks of
aneurysmal hemorrhage remain. In such cases, the risks are often
considered to be lower than the risks associated with treatment. Because
aneurysm rupture is fundamentally unpredictable, however, and because
rupture of the very smallest aneurysms is well documented, the role of
serial imaging remains undefined, and may provide a false sense of
Medical therapy is an option reserved for the treatment
of unruptured aneurysms in patients with significant risk factors for
surgery and general anesthesia. Patients with unruptured aneurysms who
have high blood pressure may be prescribed an antihypertensive (blood
pressure lowering) medication, and encouraged to follow a diet and
exercise program in addition to smoking cessation. These are important
factors that have been shown to have a significant effect on aneurysm
formation, growth, and/or rupture.
method is used for both ruptured and unruptured aneurysms. Surgical
repair of cerebral aneurysms is not advisable if they are located in
areas of the brain that are difficult to reach surgically, or if the
surgical corridor puts vital brain tissue at excessive risk. Prior to
surgery, the exact location of the aneurysm is identified through
cerebral angiography images. An operation to "clip" the aneurysm is
performed by doing a craniotomy (opening the skull surgically), and
isolating the aneurysm from the normal bloodstream. In addition, a
craniectomy, a surgical procedure in which part of the skull is removed
and left off temporarily, may be done to help relieve increased
One or more tiny titanium clips with spring
mechanisms are applied to the base of the aneurysm, allowing it to
deflate. The size and shape of the clips is selected based on the size
and location of the aneurysm. Clips are permanent, remain in place, and
generally provide a durable cure for the patient. Angiography is used to
confirm exclusion of the aneurysm from the cerebral circulation and the
preservation of normal flow of blood in the brain.
- Direct visualization of the aneurysm (which may have very
- Ability to decompress or deflate the
aneurysm after clipping
- Ability to inspect other blood vessels
in the area for smaller aneurysms
- In cases of SAH, the
advantage of enabling evacuation of some of the clotted blood
surrounding the aneurysm and the base of the brain
option for convoluted arterial systems
- Better option for
wide-neck aneurysms or those without defined openings
- Potential complications associated
with opening the cranium
- Possible damage to other structures
while clipping the aneurysm
Endovascular Surgery/Coil Embolization
The mass of the|
aneurysm, and its blood flow,
has been replaced with
In endovascular microcoil embolization, a needle is placed into the
femoral artery of the leg, and a small catheter is inserted. Utilizing
x-ray guidance, the catheter is advanced through the body’s arterial
system to one of the four blood vessels that feed the brain. A smaller
micro catheter is fed into the aneurysm, and once properly positioned, a
thin wire filament or "coil" is advanced into the aneurysm. The
flexible, platinum coil is designed to conform to the shape of the
aneurysm. Additional coils are advanced into the aneurysm to close the
aneurysm from the inside. This prevents flow of blood into the aneurysm
by causing a clot to form on the inside.
uses a tiny balloon catheter to help hold the coil in place. Although
this has been shown in several studies to increase risks, ongoing
innovations in this relatively new technology has helped improve its
efficacy. Combination stent and coiling utilizes a small flexible
cylindrical mesh tube that provides a scaffold for the coiling.
Intracranial stenting and other innovations are quite new, and
endovascular technology is in a constant state of development. These
adjuncts allow coiling to be considered for cerebral aneurysms that may
not have an ideal shape for conventional coiling.
invasive approach does not require opening the cranium
a better outcome in older and sicker patients
- Safer option for aneurysms that are difficult
- Shorter hospital stay for unruptured aneurysms –
generally one-two days
- Quicker return to work – generally one
to two weeks (unruptured aneurysms)
chance of immediate and complete aneurysm occlusion
anatomy may preclude, or negate the safety of coiling because of
convoluted vascular system
- Aneurysm shape should ideally
consist of a relatively narrow neck and wider dome (dome to neck ratio
- Higher chance of aneurysm recurrence
bruising/discomfort at the catheter leg site
- Longer follow-up
required to ensure treatment is durable
a patient with a ruptured cerebral aneurysm, surgical elimination of
the aneurysm is only the beginning. Intensive care recovery for the next
10 to 14 days is the rule, during which time a multitude of
complications related to SAH can and do occur. At some time during that
period (often immediately upon completion of surgery), cerebral
angiography or a substitute study is done to document that the aneurysm
has been eliminated. The first 2 to 5 days after SAH represent the
greatest threat of brain swelling; at which time special measures (both
medical and surgical) are used to diminish the effect of swelling on
intracranial pressure. Near the end of this initial period, the risk
period for delayed cerebral vasospasm begins, and lasts the better part
of the next 14 days. Intercurrent infections such as pneumonia are
common, and hydrocephalus may develop.
Patients who have been
treated for an unruptured aneurysm usually have no complications related
to vasospasm, swelling or hydrocephalus, and stay in intensive care for
1 to 2 days. Patients treated by coiling are often discharged from the
hospital after 1 day, and those undergoing clipping, 3 to 5 days.
and recovery after aneurysm rupture is variable. In general, those
patients who presented in good neurological condition tend to have
better recoveries. Complete cure after aneurysmal SAH is achievable, and
should be sought whenever possible, but recovery is often measured in
months to years, rather than days to weeks. Prolonged rehabilitation,
which includes physical therapy, occupational and cognitive therapy, and
speech therapy, is a very important part of recovery from hemorrhagic
stroke (aneurysm), just as it is for patients surviving ischemic stroke.
The brain has excellent capabilities for recovery, but a long timeline.
A ruptured cerebral aneurysm (aneurysmal SAH) remains among the
deadliest of afflictions and carries serious, if treatable consequences.
Some of these are:
- Behavioral changes
difficulties and short-term memory
- Decreased concentration
- Drowsiness and fatigue
- Fine motor control impairments
- Loss of balance or coordination
- Visual disturbances
- Delayed hydrocephalus
patients with unruptured aneurysm and uncomplicated surgery, recovery
is usually complete, and relatively rapid. This does not negate the
seriousness of the surgery, whether it is microsurgical or endovascular,
and the recovery period for patients to return to work is often 4 to 6
weeks, despite excellent immediate outcomes and the absence of
Cerebral Aneurysm Resources
The Brain Aneurysm Foundation