Friday, July 11, 2003

By Byron Spice, Post-Gazette Science Editor
 

When a brain aneurysm bursts, the results are often catastrophic, so people who learn they have one of these weakened blood vessels may feel as if they're walking around with time bombs in their heads.

A lot of people -- an estimated one in 20 -- have brain aneurysms, whether they know it or not. But a new international study indicates most people are at little immediate risk and don't need to be rushed to the operating room, according to a report that will appear tomorrow in The Lancet, a British medical journal.

Blood pressure causes the weakened vessel wall to bulge or balloon out and, not surprisingly, the size of that balloon is a major indicator of risk. The researchers calculate that if the aneurysm is smaller than 7 millimeters -- about a quarter of an inch -- the annual risk of it rupturing is 0.1 percent.

The location of the aneurysm, the patient's age and the patient's history of bleeding also can affect risk. Most patients, however, do not require immediate treatment, the researchers said.

"Unruptured aneurysms are relatively common in the population and are discovered more and more frequently as incidental findings as our imaging technologies improve," said Dr. David Wiebers, a Mayo Clinic neurologist and the study's principal investigator. "The discovery of an unruptured brain aneurysm need not be the cause for panic or undue alarm. They are not necessarily ticking time bombs as some have suggested."

But one effect of the study may be that more patients will receive treatment, predicted Dr. Patrick Turski, a neuroradiologist at the University of Wisconsin and past president of the American Society of Neuroradiology.

Findings from the study, which enrolled more than 4,000 patients with unruptured aneurysms at more than 60 medical centers -- including UPMC Presbyterian -- in the United States, Europe and Canada, for the first time provide doctors with guidance about which aneurysms need to be treated, noted Turski, who was not involved in the study.

Until now, doctors and their patients often had to resort to educated guesses when weighing the risks of a ruptured aneurysm with the risk and expense of surgery or other treatment.

Large aneurysms have always been recognized as bad news, but clinicians have been less sure about those measuring 6 to 7 millimeters. Though the study indicates that aneurysms smaller than 7 millimeters are not an immediate danger, it likely will result in more aggressive treatment of aneurysms that are just slightly larger, Turski said.

Aneurysms are treated either by removing them surgically or by filling them in with tiny metal coils, which are fed into the aneurysm from a catheter that is threaded through the arteries to the site.

An estimated 117,000 people in the Pittsburgh metropolitan area have brain aneurysms. Turski said it's hard to say exactly what proportion of people have aneurysms that require treatment because most aneurysms cause no symptoms and thus go undetected.

Most are discovered either incidentally when a patient undergoes a CT or MRI scan because of some other neurologic complaint, or when the aneurysm ruptures.

When an aneurysm breaks, the patient suffers a hemorrhagic stroke and has a 30 to 50 percent chance of dying. Half of those who survive end up disabled, Weibers said.

Once an unruptured aneurysm is detected, new technologies, such as CT angiography, are making it easier for doctors to monitor them, Turski said. Even small aneurysms that don't require immediate attention may later be designated as high risk if they are seen to be changing size, he noted.

(Byron Spice can be reached at bspice@post-gazette.com or 412-263-1578.)