The circulatory system is one of the body’s most essential components, delivering important nutrients to your organs. Arteries work especially hard, carrying oxygenated blood away from the heart and to the rest of your body.
Sometimes—perhaps because of all their hard work—a spot in an artery wall will become weak and balloon out, filling with blood. This is called an aneurysm. When an aneurysm in the brain ruptures, or tears, it is called a hemorrhagic stroke, according to Donald Larsen, M.D., interventional neuroradiologist and associate professor in the Keck School of Medicine of USC.
“Of all the strokes that occur, 15 percent are from a ruptured blood vessel and the other 85 percent are due to an occlusion—or blockage—of a blood vessel,” says Larsen. “So it’s not the most common cause of stroke.”
Nonetheless, ruptured brain aneurysms are extremely dangerous. In fact, 50 percent of people with a ruptured brain aneurysm die immediately, according to Larsen. Of those that survive, half have a stroke as a result and endure significant neurological distress.
He says that it is unclear exactly why brain aneurysms occur. But it is known that they have a higher rupture rate when they occur with high blood pressure and smoking, and when there’s a history of ruptured aneurysms in the family.
Luckily, a procedure honed over the past decade called coiling has made significant improvements in survival outcomes. According to one long-term study, called the International Subarachnoid Aneurysm Trial (ISAT), coiling is more likely to result in independent survival at one year than neurosurgical clipping, and the survival benefit continues for at least seven years.
“The goal of coiling is to fill the aneurysm, whether it’s ruptured or unruptured, from the inside and get it to clot off without the need for open surgery,” says Larsen. “In traditional treatment, a neurosurgeon would open up the skull, carefully expose the aneurysm and put a clip across the neck of the aneurysm.”
Coiling is a minimally invasive procedure developed in the early 1990s and FDA-approved in 1995. It uses specially designed soft coils of a platinum alloy to pack the aneurysm full. At the end of the packing process, approximately 30 percent of the aneurysm is filled with coil, the rest of it is trapped blood, says Larsen.
“The trapped blood forms a clot among the loops of the coils, preventing future rupture,” explains Larsen. “The coils stay in there for life.”
Coiling employs endovascular surgery techniques, a form of surgery that uses major blood vessels to access other regions of the body.
“Like a cardiologist, we enter the body through the femoral artery in the leg,” explains Larsen. “Then, we selectively catheterize the arteries in the neck, either carotid or vertebral arteries. Through that catheter, we insert a smaller catheter—about the size of angel hair pasta—which goes directly into the brain.”
He says that both catheters are delivered over a guide wire, the traditional way of advancing catheters through the arteries.
Because the entire surgery is done through a tiny hole in the femoral artery, the recovery time for this type of treatment is typically short.
“There is no outside intervention on the head or skull,” says Larsen. “For an unruptured aneurysm, patients are home the next day and almost always make a full recovery.”
Follow-up also tends to be minimal, he says. Less than 10 percent of the time, there’s some compaction of coils that requires an additional coil or two. For that reason, Larsen says patients are required to do follow-up angiograms at six months after the coiling procedure, and at one year.
“We do some follow-up angiography a few times after coiling, but after coiling, the aneurysm is protected from future rupture,” says Larsen.
He points out that not everybody is a candidate for coiling. At USC, an entire team takes into consideration various factors to decide whether an endovascular approach or a traditional neurosurgical approach would be most effective. Location is a large factor, says Larsen, as some aneurysms are easier for the neurosurgeon to put a clip on and some are harder and vice versa for coiling.
“We also look at the shape of the aneurysm and are looking for one that has a well-formed neck on it—like a light bulb or a cherry on a stalk,” says Larsen. “For aneurysms with a wider neck, we do have other mechanisms—we sometimes can put a stent across the neck and then fill it up with coils.”
Together, the team looks at all those factors and others, including whether the aneurysm is ruptured or not, and the age of the patient, to make the best treatment decision possible.
For more information on brain aneurysms, including possible symptoms and diagnostic procedures, Larsen recommends the Brain Aneurysm Resources website.