“Your scan shows that you have an aneurysm in your brain.” Those are words that would strike fear in the hearts of most people, conjuring up images of a life-threatening, “ticking time bomb” aneurysm.
Cerebral aneurysms are weak spots in a blood vessel inside the brain. They swell slowly over time to resemble a berry on a branch—hence the name “berry aneurysm” by which the condition is known. Berry aneurysms account for 90 percent of all brain aneurysms, but in a small number of people, the aneurysm may look more spindle-shaped (fusiform aneurysm) or blister-like (blister aneurysm).
Although all aneurysms should be taken seriously, the presence of an aneurysm in a patient does not mean that it ultimately will cause trouble. In fact, about 2-3 percent of people have an intracranial aneurysm discovered on imaging studies done for other reasons. Most of these aneurysms are tiny and carry an extremely low risk of bleeding over the person’s lifetime. For these patients, simply checking on the aneurysm periodically using noninvasive imaging, such as a special type of computed tomographic (CT) scan or magnetic resonance (MR) scan, is all that is necessary.
However, some aneurysms do grow large enough to rupture, causing bleeding around the brain, also known as subarachnoid hemorrhage. This type of bleeding, which affects about 1 in 10,000 persons each year in the United States, carries a significant risk of disability and/or death. Ruptured aneurysms require treatment, as do unruptured aneurysms that may be prone to rupture due to their size, shape, location in the brain, or patient factors such as an underlying disease that increases the risk of aneurysm formation.
Treating Brain Aneurysms
In the past, cerebral aneurysms were typically treated using an open surgical method known as clipping. During this procedure, a neurosurgeon would remove a piece of skull, gently pull back the brain to expose the aneurysm, and place a special surgical clip across the neck of the aneurysm to exclude it from the normal brain artery.
Surgical clipping was the mainstay of aneurysm treatment until 1995, when tiny platinum coils called Guglielmi Detachable Coils (GDC), which are used to close off aneurysms from inside the artery, were approved by the U.S. Food and Drug Administration (FDA). This new technique was made possible by rapid advances in the miniaturization of catheters (long, thin, plastic tubes) and guidewires that could be navigated through the arteries with the assistance of fluoroscopy, a type of real-time X-ray guidance.
The first step in aneurysm treatment is obtaining medical imaging, through a process known as angiography, to reveal the size, location and type of aneurysm in question. A common type of angiography is cardiac catheterization, which is used to study heart vessels. A similar technique, known as cerebral angiography, is used to study the vessels of the neck and brain.
Angiography involves the injection of X-ray contrast ("dye") through a catheter that has been pushed through a tiny incision made in an artery of the groin or wrist. The catheter is then navigated into the artery that needs to be investigated. During the contrast injection, multiple X-ray pictures are taken of the contrast as it flows through the arteries and into the veins, creating a “movie picture” of the person’s vessels.
If the coiling method is selected to treat the aneurysm, a specially trained neurointerventionalist uses an endovascular (”through the artery”) approach to enter the aneurysm and block it off from the inside with the GDC coils. Using catheters and guidewires designed specifically for this treatment, the neurointerventionalist carefully inserts a whole series of coils inside the aneurysm, adding smaller coils inside the larger ones to create a “coil ball” that is similar in concept to those Russian dolls that are nested one inside the other. Using this technique, the aneurysm is blocked off progressively; once no more coils can be placed, the catheters are removed and the tiny incision is closed.
Not all aneurysms are amenable to simple coiling, however. In an aneurysm with a wide neck, keeping the coil ball within the berry formation may require the assistance of a stent, which is a flexible, perforated metallic tube used to cover the neck of the aneurysm. The stent acts as a barrier to keep the coils from escaping into the parent artery, where they could potentially block blood flow and lead to a stroke.
Selecting the Appropriate Treatment
In some situations, open surgery is a better treatment option for the patient. When a ruptured aneurysm has caused significant bleeding into the brain tissue, open surgery allows the neurosurgeon to clip the aneurysm and remove the blood clot at the same time. In other situations, the aneurysm may not be accessible by endovascular means, or may involve important arterial branches that need to be reconstructed using clips instead of coils or stents. In these situations, the neurointerventionalist and neurosurgeon work together to decide on the best treatment approach for the patient.
In fusiform or blister aneurysms, the entire wall of the blood vessel is diseased and requires reconstruction. To treat this condition, modern devices called flow diverters, which are finely woven tubes made of metallic mesh, are placed in the affected part of the vessel. Then, over the course of several months, the inner lining of the blood vessel slowly grows over the device, incorporating the flow diverter into the wall itself. The lengthy healing process allows small arteries that arise from the diseased segment to remain open. However, due to the extended amount of time required to achieve aneurysmal healing in this way, these devices usually are not suitable for ruptured aneurysms.
Aneurysm Treatment Guidelines
I wish to reiterate that aneurysms need to be treated only if they are ruptured, are causing symptoms, or have dangerous features such as a large size or an irregular dome. Aneurysms also should be treated if they are associated with certain diseases or family traits that increase their risk of rupture.
When aneurysms are found incidentally, a person’s best course of action is to consult with a doctor who routinely sees aneurysm patients. If endovascular treatment is recommended, most patients can have surgery one day and be discharged the next. Follow-up appointments consist of MR angiography (MRA) and an office visit on a yearly basis for three years, or longer if necessary. Tiny aneurysms can be followed with MRA every two or three years, as needed.
While having a cerebral aneurysm may sound scary and is understandably a cause for concern, patients and their families can take heart in the fact that today we have powerful diagnostic and treatment options that enable us to provide safe, effective, life-saving care.
Working at the Frontiers of Aneurysm Treatment
In 1990, the world’s first patient to be treated with Guglielmi Detachable Coils (GDC) underwent the procedure at the University of California, Los Angeles (UCLA), where the device was developed by Guido Guglielmi, MD, and Fernando Vinuela, MD. Lee Jensen, MD, was a member of the team that treated the first four patients with GDC coils. In 1991, Dr. Jensen joined Jacques Dion, MD—another UCLA physician who was her mentor and part of the GDC team—at the University of Virginia (UVA).
“UVA was one of only 20 sites in the world that was asked to participate in the U.S. Food and Drug Administration (FDA) trial, which approved the GDC coil for use in patients with ruptured aneurysms who were too sick to have open surgery,” says Dr. Jensen.
Over the next 10 years, Dr. Jensen helped design and evaluate numerous “improved” coils, intended to make aneurysm treatment safer, faster and more durable. In addition, she trained physicians from all over the world on how to use the coil, as well as other devices that were developed later, such as intracranial stents used to assist in the coiling of wide-neck aneurysms.
Because of the effectiveness and safety profile of the endovascular approach to the treatment of cerebral aneurysms, the FDA ultimately approved the coil for use in all aneurysm patients who meet the criteria for having the coil procedure. Today, most patients are offered coiling—or in some cases, another technique called flow diversion—as the first-line treatment for their aneurysm.