A cerebral aneurysm is a bulging abnormality of a brain artery that often
resembles a sac or a balloon. It is associated with a focal weakness of
the arterial wall; the cause is unknown, although a family history may
be present in some cases.
Cerebral aneurysms are dangerous. Bleeding, or rupture, of a cerebral aneurysm
causes death or neurological disability in a high percentage of cases.
The type of bleeding caused by cerebral aneurysm rupture is called Subarachnoid
For this reason, aneurysms cannot be considered benign entities, even when
they cause no symptoms. Most aneurysms cause no symptoms until they rupture.
Since rupture is unpredictable, neurosurgical intervention is often recommended
when aneurysms are discovered incidentally (without bleeding). This is
true of both larger and smaller aneurysms, since size alone does not predict
which aneurysms will bleed.
Cerebral aneurysms are not infrequently multiple, and may sometimes be
associated with a family history.
Types of Neurosurgical Intervention
These are broadly divided into microsurgery (via craniotomy, or opening
of the skull) and endovascular (catheter-based techniques that are performed
through a tiny incision in the leg, instead of opening the skull).
Microsurgical clipping is performed using an operating microscope at the
base of the brain, after a craniotomy is performed. Once the aneurysm
is isolated after tracing its parent blood vessel, a titanium clip is
applied in such a way as to exclude the aneurysm from the normal circulation,
which is preserved.
Endovascular neurosurgery is also known as Interventional Neuroradiology.
Endovascular techniques for cerebral aneurysm include platinum microcoils
(deposited within the aneurysm), stents (used to bridge the bottom of
some aneurysms), and balloons (used to widen constricted blood vessels,
or sometimes in conjunction with coils).
In coil embolization for aneurysm, the aneurysm is excluded from the normal
circulation by the deposition of platinum microcoils delivered through
a microcatheter entering the body from the leg. No incision is made on
the head. Once an aneurysm is coiled, it is recommended to undergo cerebral
angiography at half-year intervals for 2 years, to monitor the permanence
Procedures performed by Dr. Thomas, whether microsurgical or endovascular,
are under general anesthesia and are usually attended by neurophysiologic
monitoring, which is the monitoring of the brain’s electrical activity,
to maximize the safety of these procedures.
Endovascular and microsurgical techniques can be combined effectively for
optimal treatment of complex conditions.
Which form of intervention is safest for the patient is a complex medical
decision based on the shape and size of the aneurysm, the experience of
the physician in the different procedures, and on the health and preferences
of the patient. Both techniques are forms of brain surgery, and require
the highest levels of experience and clinical judgment.
Because of the dangerous nature and complexity of cerebral aneurysms, it
is advantageous for the neurosurgeon to have access to all current treatment
modalities. This makes for balanced, thoughtful treatment decisions. Sometimes
multiple modalities may be used for a single patient.
Most cerebral aneurysms can be eliminated successfully using a measured
and well-planned approach to treatment.
aans.org for more information.