Neurointerventional Radiology Procedures
brain aneurysm, also called a cerebral or intracranial aneurysm, is an
abnormal bulging outward of one of the arteries in the brain. It is
estimated that up to one in 15 people in the United States will develop a
brain aneurysm during their lifetime.
Brain aneurysms are often discovered when
they rupture, causing a subarachnoid hemorrhage, or bleeding into
the brain and the space closely surrounding the brain called the
subarachnoid space. Subarachnoid hemorrhage from a ruptured brain
aneurysm can lead to a hemorrhagic stroke, brain damage, and death.
The main goals of treatment once an
aneurysm has ruptured are to stop the bleeding, to prevent potential
permanent damage to the brain, and to reduce the risk of recurrence.
Unruptured brain aneurysms are sometimes treated to prevent rupture.
Surgery or minimally-invasive endovascular
coiling techniques can be used in the treatment of brain aneurysms. It
is important to note, however, that not all aneurysms are treated at the
time of diagnosis or are amendable by either forms of treatment.
Patients need to consult a neurovascular specialist to determine if they
are candidates for either treatment.
Diagnosis of Brain Aneurysms
Diagnosis of a ruptured cerebral aneurysm is commonly made by
finding signs of subarachnoid hemorrhage on a CT scan. The CT scan is a
computerized test that rapidly X-rays the body in cross-sections as the
body is moved through a large, circular machine. If the CT scan is
negative but a ruptured aneurysm is still suspected, a lumbar puncture
is performed to detect blood in the cerebrospinal fluid that surrounds
the brain and the spinal cord.
To determine the exact size and shape of an aneurysm (ruptured or unruptured), neuroradiologists use either cerebral angiography or tomographic angiography.
Cerebral angiography, the traditional method, involves introducing a
catheter (small plastic tube) into an artery, usually in the leg, and
steering it through the blood vessels of the body to the artery involved
with the aneurysm. A special dye, called a contrast agent, is injected
into the patient's artery, and its distribution is shown on X-ray
projections. This method may not detect some aneurysms due to
overlapping structures or spasm.
Computed Tomographic Angiography (CTA) is an alternative to the
traditional method and can be performed without the need for arterial
catheterization. This test combines a regular CT scan with a contrast
dye injected into a vein. Once the dye is injected into a vein, it
travels to the brain arteries, and images are created using a CT scan.
These images show exactly how blood flows into the brain arteries.
Coil Embolization or Endovascular Coiling
Endovascular therapy is a minimally
invasive procedure that accesses the treatment area from within the
blood vessel. In the case of aneurysms, this treatment is called coil
embolization, or "coiling". In contrast to surgery, endovascular
coiling does not require open surgery. Instead, physicians use real-time
X-ray technology, called fluoroscopic imaging, to visualize the
patient's vascular system and treat the disease from inside the blood
Endovascular treatment of brain aneurysms involves
insertion of a catheter (small plastic tube) into the femoral artery in
the patient's leg and navigating it through the vascular system, into
the head and then into the aneurysm. Tiny platinum coils
are threaded through the catheter and deployed into the aneurysm,
blocking blood flow into the aneurysm and preventing rupture. The coils
are made of platinum so that they are visible via X-ray and
flexible enough to conform to the aneurysm shape. This
endovascular coiling, or filling, of the aneurysm is called embolization
and can be performed under general anesthesia or light sedation. More
than 125,000 patients worldwide have been treated with detachable
To get to the aneurysm, surgeons must
first remove a section of the skull, a procedure commonly known as a
craniotomy. The surgeon then spreads the brain tissue apart and places a
tiny metal clip across the neck of the vessel to stop blood flow into
the aneurysm. After clipping the aneurysm, the bone is secured in its
original place, and the wound is closed.
Endovascular Coiling v. Surgical Clipping
Treatment of Ruptured Aneurysms
Until recently, most of the studies
regarding surgical clipping and endovascular treatment of brain
aneurysms were either small-scale studies or were retrospective studies
that relied on analyzing historical case records. The only multi-center
prospective randomized clinical trial - considered the gold-standard in
study design - comparing surgical clipping and endovascular coiling of
ruptured aneurysm is the International Subarachnoid Aneurysm Trial
The study found that, in patients equally suited for both
treatment options, endovascular coiling treatment produces
substantially better patient outcomes than surgery in terms of survival
free of disability at one year. The relative risk of death or
significant disability at one year for patients treated with coils was
22.6 percent lower than in surgically-treated patients.
results were so compelling that the trial was halted early after
enrolling 2,143 of the planned 2,500 patients because the trial steering
committee determined it was no longer ethical to randomize patients to
be treated with neurosurgical clipping. However, long-term follow-up
will be essential to assess the durability of the substantial early
advantage of endovascular coiling over conventional neurosurgical
clipping for the treatment of brain aneurysms.
It is important to
note that patients enrolled in the ISAT were evaluated by both a
neurosurgeon as well as an endovascular coiling specialist, and both
physicians had to collaborate and agree that the aneurysm was treatable
by either technique. This study provides compelling evidence that, if
medically possible, all patients with ruptured brain aneurysms should
receive an endovascular consultation as part of the protocol for the
treatment of brain aneurysms.
Treatment of Unruptured Aneurysms
Although no multi-center randomized
clinical trial comparing endovascular coiling and surgical treatment of
unruptured aneurysms has yet been conducted, retrospective analysis has
found that endovascular coiling is associated with less risk of negative
outcomes, shorter hospital stays and shorter recovery times compared
Studies have shown that:
- Average hospital stays are more than twice as long with surgery as compared to endovascular coiling treatment
- Four times as many surgical patients report new symptoms or disability after treatment as compared to coiled patients
- There can be a dramatic difference in recovery times. One study
showed that surgically-treated patients had an average recovery time of
one year compared to coiled patients who recovered in 27 days