Aneurysm treatment; schematics

An intracranial aneurysm is a weak spot in a wall of an intracranial artery (usually occurring at an arterial branch point) that causes a small outpouching of the arterial wall and lacks the normal structural layers found in most arteries.

An aneurysm often has the appearance of a small berry or sac, thus may be referred to as a berry or a saccular aneurysm. Because the wall of an aneurysm is extremely thin relative to the artery from which is has developed (parent artery), it has the propensity to rupture, causing hemorrhage into and around the base of the brain. One of the most important causes of complications or death after aneurysm rupture is recurrent rupture; therefore, it is very important to attempt to seal off a ruptured aneurysm from its parent artery and prevent a second, often fatal, rupture.

To prevent the second rupture, neurosurgeons have traditionally performed open cranial surgery by removing a piece of the skull and directly approaching the aneurysm to place a small clip across the base of the aneurysm (craniotomy with clipping). Although the surgical procedure has been extremely effective at sealing the aneurysm, the surgery itself is associated with a significant incidence of death and complications.

Approximately 15 years ago, surgeons began implanting tiny helical-shaped platinum coils in aneurysms that had recently ruptured. To perform this endovascular procedure, the coils are inserted within a tiny microcatheter that is placed inside the patient's arterial system through a small incision in the femoral artery in the groin. The microcatheter is advanced through the arterial system all the way up to and inside the aneurysm; the platinum coils pass then through the microcatheter and into the aneurysm to fill and effectively seal off (occlude) the aneurysm. Large, international studies have recently proven that the coiling of intracranial aneurysms appears to have the same effectiveness as open cranial surgery, but coiling appears to be considerably safer for patients than open surgery. Additional studies are underway to ascertain whether the long-term durability of endovascular coiling is as effective as surgical clipping. Because of the safety issues, however, many patients prefer the minimally invasive endovascular coiling procedure.

The coiling procedure was initially found to be most effective for aneurysms with small openings or necks. Recently, newer techniques have been developed that facilitate the treatment of larger and more complex aneurysms using an endovascular approach. Neurosurgeons at the State University of New York at Buffalo and Kaleida Health System have been leaders in the performance of minimally invasive endovascular treatment of intracranial aneurysms for more than 15 years.

Our group was among the first to use the newer coiling techniques and has led the way in the treatment of more complex aneurysms using adjunctive devices, such as intravascular stents (small flexible mesh cylinders made of stainless steel or alloys), to prevent aneurysm rupture by reconstructing or rebuilding the intracranial artery from within.

The ideal time to treat an intracranial aneurysm is before it ruptures. Once an aneurysm reaches a certain size or demonstrates other characteristics suggestive of impending rupture, treatment should be instituted. Many aneurysms are discovered incidentally and some cause symptoms other than rupture, which facilitates diagnosis and treatment. Recent studies have proven that the risk of open cranial surgery for unruptured aneurysms is much higher than we previously thought. Again, newer minimally invasive endovascular approaches are proving much safer than open surgical approaches.

Risk factors

:	Smoking
:	Obesity
:	Hypertension

Warning signs

The majority of people with aneurysms do not experience warning signs that they are at risk of hemorrhage. About 40% of patients with aneurysms, however, may experience the following symptoms:

:	Nausea or vomiting
:	Pain above and behind the eye
:	Numbness or weakness in extremities
:	Neck pain
:	Headache confined to a specific area
:	Visual difficulties
:	Speech difficulties
:	Memory problems
:	Seizures

When these symptoms are present, assessment procedures should include a CT scan or magnetic resonance imaging (MRI). These techniques can help to identify aneurysms before they rupture. A more accurate diagnosis is typically made via cerebral angiography. This involves the injection of dye into the blood vessels through a catheter or tube. These images define the anatomy and location of an aneurysm with great detail and form the basis on which treatment planning using either can be performed. Treatment using either open surgery with craniotomy and surgical clipping of the aneurysm or endovascular surgery with internal occlusion of the aneurysm can then be undertaken. There are benefits and risks to either approach and the treatment team must comprise of neurosurgeons with expertise in both types of procedures in order to achieve optimal outcomes.

There are 3 different types of aneurysms:

Berry- the most common type of aneurysm, these are small and shaped like a blister, balloon, sac or even a little red "berry" appearance at the time of craniotomy and direct surgical exposure. These aneurysms most often arise at a blood vessel branch point or bifurcation where a relatively weak point is subject to high stress factors from the flowing blood.

Fusiform - this type of aneurysm is elongated and shaped like a spindle. Rather than a balloon or bulge from one side of the blood vessel wall, the entire circumference of the blood vessel has become involved in the formation of a fusiform aneurysm.

Dissecting - this type of aneurysm occurs when blood passes through a tear in the inner layer of the blood vessel wall that causes the wall to split weakening its ability to contain the flow of blood. The result can be aneurysmal dilatation of the blood vessel, narrowing of the main flow channel for blood to reach the brain causing stroke, or even rupture through the weakened blood vessel wall causing subarachnoid hemorrhage.