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 Hemorrhage.
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 of occlusion.
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.
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