Brain aneurysm:

A 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.

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 vessel.
They insert   a catheter  into the
femoral artery in the patient's leg and
navigating it through the vascular
system, into the head and 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 can be visible
via X-ray and be 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.

Until recently, most studies on the
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 (ISAT)1 .

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

The study 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
neurosurgical clipping.

A brain bypass is the brain's
equivalent of a heart  bypass. It
involves rerouting blood flow around a
blocked or damaged or abnormal
blood vessel so that the region of brain
involved can continue to get blood
Brain bypass operations are carried
out by a relatively few neurosurgeons
with experience in this area of
neurovascular surgery.
Brain bypass is done  for two main  

  • Symptomatic blockage  or
    traumatic injury of a major brain
    artery such as the internal
    carotid artery.
  • A brain aneurysm that cannot be
    successfully obliterated using a
    clip or coil, but instead its parent
    artery requires to be sacrificed
    for the aneurysm to be
    effectively treated.