Brain Aneurysms: To Operate or Not to Operate?

Medically Reviewed by Jacqueline Brooks, MBBCH, MRCPsych
From the WebMD Archives

Oct. 30, 2000 -- For those with a brain aneurysm, it can be a bit like living with a tiny time bomb ticking in their head. What's worse, they might not know it's there, it doesn't bother them, and maybe it never will. In fact, the risk of the aneurysm exploding is only one in 100 each year. But if it does blow up, the chances of surviving are only one in two, and the odds of surviving without severe brain damage are only one in four.

Having a brain aneurysm -- a blood-filled pouch bulging out from a weak spot in the wall of a brain artery -- is just like that. Some people with aneurysms have headaches or vision problems, but most have no symptoms until the aneurysm ruptures or bursts open, bleeding into the brain tissue and causing stroke, brain damage, or even death. Between 1% and 5% of Americans may have unruptured brain aneurysms, and about 15,000 Americans each year have a stroke from a ruptured aneurysm.

Should screening be done to find unruptured brain aneurysms? And if found, should there be an operation? Tackling these issues head-on, the American Heart Association Stroke Council task force published guidelines for aneurysm screening and treatment in the Oct. 31 issue of Circulation: Journal of the American Heart Association.

"The consequences of aneurysm rupture are so severe that deciding which patients to treat is very important," task force chair Joshua B. Bederson, MD, tells WebMD. "All treatments carry some risk, which is why we need to individualize treatment.

"No one can tell if an aneurysm is going to rupture just by looking at it," says Bederson, an associate professor of neurosurgery and director of cerebrovascular surgery at the Mount Sinai Hospital in New York City. The task force studied features of the patients, the aneurysms, and the surgeons to try to decide when an operation should occur.

The largest international study to date showed that unruptured aneurysms smaller than 10 mm -- about the size of a raisin -- had a tiny risk of rupture, provided the patient had no earlier history of bleeding from a brain aneurysm, and higher risks associated with surgical treatment.

"This surprised many experts who were accustomed to treating nearly all identified unruptured aneurysms," says S. Claiborne Johnston, MD, MPH, an assistant professor of neurology at University of California at San Francisco who reviewed the guidelines for WebMD. As the task force could not rule out the possibility of bleeding even from small aneurysms, it recommended that patients with small aneurysms be considered for surgery, depending on their age and other factors.

"I'm very supportive of surgery in younger patients, but more conservative in the oldest patients with the smallest aneurysms," Bederson says. "It boils down to how old is the patient, and what is their life expectancy?"

Patients age 65 or older had four to five times as many complications from surgery -- including death -- as did patients younger than age 45. And as older patients have a shorter remaining life span than do younger patients, they have a shorter period of being at risk for aneurysm rupture.

Almost half of patients die within 30 days of aneurysm rupture, and about half of the survivors have irreversible brain damage. "So if your brain aneurysm ruptures, you have only a one in four chance of doing well," Bederson says.

Aneurysms that are large, growing, or causing symptoms are more likely to rupture. Other factors favoring surgery include history of rupture from another aneurysm or having a relative with an aneurysm. If unruptured aneurysms are not operated on, they should be followed periodically with brain scans to see if they are getting larger.

"It's important to seek out a center that has a good record of treating aneurysms," Bederson says. "But determining which centers have a good record can be difficult, even for a surgeon, let alone for a layperson."

Surgeons and hospitals have no central board accrediting them on their performance of aneurysm surgery, nor are they required to publish their own track record in this area. Studies in medical journals suggest that the death rate ranges from zero to 7%, and the complication rate from 4% to 15%.

Although "the treatment of an unruptured [brain] aneurysm is generally very safe, and the outcome is usually good," Bederson explains that centers performing more than 10 aneurysm surgeries per year had less than half the death rate of centers rarely performing aneurysm surgery (5% vs. 11%).

The task force did not recommend widespread screening with brain scans for people without symptoms, but felt it should be considered in individuals with two or more close relatives with aneurysms. Patients who already have had a ruptured aneurysm also should have brain scans periodically, as the rate of new aneurysm formation is 1% to 2% per year.

More information is available from the Brain Aneurysm Foundation Inc. by calling (617) 723-3870 or visiting the web site at