Endovascular Treatment of Ruptured Intracranial Brain Aneurysms,
Arteriovenous Malformations and Carotid Cavernous Fistulae
Chavdar Bachvarov, MD
Department of Radiology
St. Marina University Hospital, Varna
The subarachnoid haemorrhage after ruptured brain aneurysm is a state of
emergency. Approximately 15% of patients with aneurysmal subarachnoid
haemorrhage (SAH) die before reaching the hospital. Of those who survive,
66% can receive major neurological deficit. Most of the deaths from
subarachnoid haemorrhage are due to rapid and massive brain injury from the
initial bleeding which is not correctable by medical and surgical interventions.
Every 4 out of 7 people who recover from a ruptured brain aneurysm will have
disabilities. Brain aneurysms are most prevalent in people ages 35 – 60, but can
occur in children as well. The median age when aneurysmal haemorrhagic
stroke occurs is 50 years of age and there are typically no warning signs. Most
aneurysms develop after the age of 40. Most aneurysms are small, about 1/8
inch to nearly one inch, and an estimated 50 to 80 percent of all aneurysms do
not rupture during the course of a person’s lifetime. Aneurysms larger than one
inch are referred to as “giant” aneurysms and can pose a particularly high risk
and can be difficult to treat. Women, more often than men, suffer from brain
aneurysms at a ratio of 3:2. African-Americans suffer twice the rate of rupture
of whites (a 2.1:1 ratio). Hispanics experience nearly twice the rate of rupture of
whites (a 1.67:1 ratio). Ruptured brain aneurysms account for 3 – 5% of all new
strokes. Subarachnoid haemorrhage (SAH) is one of the most feared causes of
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acute headache upon presentation to the emergency department. Headache
accounts for 1 – 2% of the emergency room visits and up to 4% of visits to the
primary care offices. Among all the patients who present to the emergency room
with headaches, approximately 1% has subarachnoid haemorrhage. One study
raises the figure at 4%. Accurate early diagnosis is critical, as the initial
haemorrhage may be fatal, may result in devastating neurologic outcomes, or
may produce minor symptoms. Despite widespread neuroimaging availability,
misdiagnosis or delays in diagnosis occurs in up to 25% of patients with
subarachnoid haemorrhage (SAH) when initially presenting for medical
treatment. Failure to do a scan results in 73% of these misdiagnoses. This makes
SAH a low-frequency, high-risk disease. There are almost 500,000 deaths
worldwide each year caused by brain aneurysms and half the victims are
younger than 50. Based on a 2004 study, the combined lost wages of survivors
of brain aneurysm rupture and their caretaker for a year were $138,000,000 the
cost of a brain aneurysm treated by clipping via open brain surgery more than
doubles in cost after the aneurysm has ruptured. The cost of a brain aneurysm
treated by coiling, which is less invasive and is done through a catheter,
increases by about 70% after the aneurysm has ruptured. 10 – 15% of patients
diagnosed with a brain aneurysm will harbour more than one aneurysm.
What is endovascular coiling?
Endovascular coiling is a procedure performed to block blood flow into an
aneurysm (a weakened area in the wall of an artery). Endovascular coiling is a
more recent treatment for brain aneurysms; it has been used in patients since
1991. Endovascular coiling is a minimally invasive technique, which means an
incision in the skull is not required to treat the brain aneurysm. Rather, a
catheter is used to reach the aneurysm in the brain. During endovascular coiling,
a catheter is passed through the groin up into the artery containing the
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aneurysm. Platinum coils are then released. The coils induce clotting
(embolization) of the aneurysm and, in this way, prevent blood from getting into
it.
How is endovascular coiling performed?
A microcatheter is inserted through the initial catheter. The coil is attached to
the microcatheter. When the microcatheter has reached the aneurysm and has
been inserted into the aneurysm, an electrical current is used to separate the coil
from the catheter. The coil seals off the opening of the aneurysm. The coil is left
in place permanently in the aneurysm. Depending on the size of the aneurysm,
more than one coil may be needed to completely seal off the aneurysm. The
coils used in this procedure are made of soft platinum metal, and are shaped like
a spring. These coils are very small and thin, ranging in size from about twice
the width of a human hair (largest) to less than one hair's width (smallest).
Fluoroscopy (a special type of x-ray, similar to an x-ray "movie") aids in this
procedure. The catheter, which is inserted into an artery in the groin, is guided
by a small wire inside of the catheter along the length of the blood vessel to
reach the area of the aneurysm. The physician uses fluoroscopy to guide the
catheter to the aneurysm's location in the brain.
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3D mapping aneurysm taken, prior to coiling
Coiled aneurysm
Risk factors for development and rupture of an intracranial aneurysm
Cerebral aneurysms can be congenital, resulting from an inborn abnormality in
an artery wall. Cerebral aneurysms are also more common in people with
certain genetic diseases, such as connective tissue disorders and polycystic
kidney disease, and certain circulatory disorders, such as arteriovenous
malformations (snarled tangles of arteries and veins in the brain that disrupt
blood flow). Other causes include trauma or injury to the head, high blood
pressure, infection, tumours, atherosclerosis (a blood vessel disease in which
fats build up on the inside of artery walls) and other diseases of the vascular
system, cigarette smoking, and drug abuse. Some investigators have
speculated that oral contraceptives may increase the risk of developing
aneurysms. Aneurysms that result from an infection in the arterial wall are
called mycotic aneurysms. Cancer-related aneurysms are often associated with
tumours of the head and neck. Drug abuse, particularly the habitual use of
cocaine, can inflame blood vessels and lead to the development of brain
aneurysms. Brain aneurysms can occur at any age. They are more common in
adults than in children and slightly more common in women than in men.
People with certain inherited disorders are also at higher risk. All cerebral
aneurysms have the potential to rupture and cause bleeding within the brain. In
addition, the condition and size of the aneurysm affects the risk of rupture.
How are aneurysms classified?
There are three types of cerebral aneurysm. A saccular aneurysm is a rounded
or pouch-like sac of blood that is attached by a neck or stem to an artery or a
branch of a blood vessel. Also known as a berry aneurysm (because it
resembles a berry hanging from a vine), this most common form of cerebral
aneurysm is typically found on arteries at the base of the brain. Saccular
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aneurysms occur most often in adults. A lateral aneurysm appears as a bulge
on one wall of the blood vessel, while a fusiform aneurysm is formed by the
widening along all walls of the vessel. Aneurysms are also classified by size.
Small aneurysms are less than 11 millimetres in diameter (about the size of a
large pencil eraser), larger aneurysms are 11-25 millimetres (about the width
of a dime), and giant aneurysms are greater than 25 millimetres in diameter
(more than the width of a quarter).
Method
Most cerebral aneurysms go unnoticed until they rupture or are detected by
brain imaging that may have been obtained for another condition. Several
diagnostic methods are available to provide information about the aneurysm
and the best form of treatment. The tests are usually obtained after a
subarachnoid haemorrhage, to confirm the diagnosis of an aneurysm.
Angiography is a dye test used to analyze the arteries or veins. An
intracerebral angiogram can detect the degree of narrowing or obstruction of
an artery or blood vessel in the brain, head, or neck, and can identify changes
in an artery or vein such as a weak spot like an aneurysm. It is used to
diagnose stroke and to precisely determine the location, size, and shape of a
brain tumour, aneurysm, or blood vessel that has bled. This test is usually
performed in a hospital angiography suite. Following the injection of a local
anaesthetic, a flexible catheter is inserted into an artery and threaded through
the body to the affected artery. A small amount of contrast dye (one that is
highlighted on x-rays) is released into the bloodstream and allowed to travel
into the head and neck. A series of x-rays is taken and changes, if present, are
noted.
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Computed tomography (CT) of the head is a fast, painless, non-invasive
diagnostic tool that can reveal the presence of a cerebral aneurysm and
determine, for those aneurysms that have burst, if blood has leaked into the
brain. This is often the first diagnostic procedure ordered by a physician
following suspected rupture. X-rays of the head are processed by a computer
as two-dimensional cross-sectional images, or “slices,” of the brain and skull.
Occasionally a contrast dye is injected into the bloodstream prior to scanning.
This process, called CT angiography, produces sharper, more detailed images
of blood flow in the brain arteries. CT is usually conducted at a testing facility
or hospital outpatient setting.
Magnetic resonance imaging (MRI) uses computer-generated radio waves and
a powerful magnetic field to produce detailed images of the brain and other
body structures. Magnetic resonance angiography (MRA) produces more
detailed images of blood vessels. The images may be seen as either threedimensional pictures or two-dimensional cross-slices of the brain and vessels.
These painless, non-invasive procedures can show the size and shape of an
aneurysm and can detect bleeding in the brain.
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MATERIALS
Fig.1 Patients,divided by sex
Fig.2 Types of procedures
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Fig.3 Number of patients through the years.
Fig.4 Age groups - aneurysms /first row/ and AVM /second row/.
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RESULTS
Fig.5 Number and location of embolized aneurysms in anterior circulation
Разпределение руптуриралите аневризми според
размера на емболизирания аневризмален сак
Малки
Средни
7%
Големи
Гигантски
2%
29%
62%
Fig.6 Embolized aneurysms, divided by size
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Fig.7 Time of embolization and vasospasm
Fig.8 Grade of embolization of ruptured aneurysms
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Fig.9 Distribution of patients according to Glasgow outcome scale /GOS/
DISSCUSION
The general incidence of SAH in developed countries is 10 per 100,000
population per year. If the prevalence of UIAs is taken to be 1%, the risk of
SAH for an individual with a UIA may be calculated as 1% per year.
Recent studies have indicated that intracranial aneurysm size may be a primary
determinant of rupture probability and many earlier series have implicated size
as an important factor in aneurysm rupture. The more prevalent size of the
aneurysm to treat may differ in accordance with the location of the aneurysm.
The two most frequent complications of endovascular treatment of intracranial
aneurysms are thromboembolic events and intraoperative rupture. The rate of
thromboembolic events was significantly higher in smokers, in patients with
large aneurysms, and in patients with wide-neck aneurysms. Aneurysm rupture
was more frequent in MCA aneurysms. Smoking is associated with an
increased risk of aneurysmal subarachnoid haemorrhage and related delayed
neurologic deterioration. This is probably due to several factors, including the
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increased incidence of vasospasm and cerebrovascular dysfunction promoted
by tobacco, and may help explain the higher risk of thromboembolic
complications. Large aneurysms are also associated with a significantly higher
risk of thromboembolic events. This may be due to more frequent intraaneurysmal clotting before treatment and to the larger volume of clot induced
by coil occlusion of large aneurysms. Wide-neck aneurysms are also
associated with a higher risk of thromboembolic events. Several factors may
be associated with this increased risk. In wide-neck aneurysms, the surface of
coils at the level of the neck is more important than in small-neck aneurysms,
leading to an increased risk of thrombus formation. The fact that the neck is
wide can also facilitate the migration of an intraaneurysmal clot. Finally, the
risk of protrusion of coils into the parent vessel is likely higher in wide-neck
aneurysms and can also increase the risk of thromboembolic events. The risk
of intraoperative rupture is significantly higher in patients younger than 65
years, probably because the goal of treatment is different for younger patients
than for older patients. In young patients, treatment is mandatory to avoid the
risk of repeat bleeding. With advanced age, the need for emergent treatment of
the aneurysm is counterbalanced by the physiologic status of the patient and
the need for very dense packing of the aneurysm is less, leading to less
“aggressive” treatment and a lower risk of intraoperative rupture. Two factors
may help explain the reduction of intraoperative rupture in patients with
elevated blood pressure: better control of blood pressure during endovascular
treatment and modifications of the aneurysmal wall, arterial wall, or
intraaneurysmal flow in patients with elevated blood pressure. The risk of
intraoperative rupture is in MCA and vertebrobasilar system aneurysms than in
anterior cerebral artery/anterior communicating artery and internal carotid
artery aneurysms.
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CONCLUSION
Endovascular treatment of ruptured intracranial aneurysms has been accepted
as an alternative to surgical clipping. Selective embolization of ruptured
intracranial aneurysms in patients is effective. However, the morbidity and
mortality rates are higher with high HH grades. This finding suggests that
timing of treatment should be based on the patient’s initial clinical status.
Long-term clinical and angiographic follow-up after coiling of ruptured
aneurysms confirms its efficacy as a primary treatment technique. Rebleeding
rates after treatment are low, but recanalization remains an issue, even in
aneurysms that are initially completely occluded. Long-term imaging followup is advised. Initial angiographic appearance is not a good predictor of
haemorrhage, recanalization, and long-term outcome.
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