Jets of blood beat against the cigar-shaped aneurysm pressing on Ursula Spear’s brain stem. The bulging artery was inoperable, one set of doctors pronounced — and likely to eventually burst and kill her.
Then Dr. Michael Lawton offered hope, thanks to a novel technology that produces 3-D images of the blood pounding through brain arteries almost like engineers visualize wind currents around airplanes.
Guided by those models, Lawton cut into Spear’s brain and rerouted part of the blood flowing through the critical artery, easing stress on this rare but particularly dangerous type of aneurysm until it essentially healed over.
“There are a lot of people probably being told, ‘My god, this is a horrible aneurysm, we have nothing to offer you, you’ll probably be dead in two to five years,”’ says Lawton, a neurosurgeon at the University of California, San Francisco. “We think we have something to offer that may stop this downward spiral.”
The modeling is an experiment funded by the National Institutes of Health. If it pans out, it could help doctors better predict which aneurysms are likely to burst and whether to attempt treatment, says Dr. John Marler of NIH’s National Institute of Neurological Disorders and Stroke.
“That’s just the judgment of the surgeon until now,” says Marler, calling the research “pretty unique. ... This gives you more data to base your best (treatment) guess on.”
Brain aneurysms are bulges, or weak spots, in artery walls. Some never cause problems. Others can burst, causing dangerous bleeding into the brain. About half of patients with ruptured brain aneurysms die. The only way to predict whether an aneurysm is likely to burst is by its size, and whether it’s growing.
About 3 percent of the population is thought to have some type of brain aneurysm. Most are saccular aneurysms, sacs that look like berries hanging from an artery’s side. Treatment can be straightforward: Put a clip around the opening, or thread a miniature wire coil through arteries until it reaches and fills up the sac — both ways of blocking blood flow into the aneurysm.
More rare, and much more difficult to treat, are fusiform aneurysms like Spear’s. They encircle arteries — usually the major basilar artery by the brain stem, where the brain and spinal cord meet — and can’t simply be blocked off. The bleeding risk aside, a large basilar aneurysm can press on the brain stem, causing serious nerve-related symptoms.
Indeed, excruciating pain and arms and legs suddenly too weak for gardening sent Spear, 57, to her doctor last summer. A brain scan three years ago had detected an aneurysm so small that the physician had never mentioned it. A new MRI showed that aneurysm now was a giant. Neurologists she consulted in her hometown of Sacramento said there was no treatment. But one had heard about the San Francisco research, and sent her to Lawton.
Describing these aneurysms, Lawton uses terms more commonly associated with aircraft: jets, velocity, shear stress.
Blood flow and air flow are governed by the same physics, he explains — it’s a matter of measuring how unusually harsh blood currents erode normally elastic artery walls.
A colleague, Dr. William Young, had created a way to model blood flow during a different ailment, a snarling of brain blood vessels called arterio-venous malformations. So Lawton turned to Young to adapt the technology for aneurysms.
First, dye is injected into patient arteries to track blood flow. A computer superimposes that information over brain scans, to compose a 3-D model of the aneurysm. Then, on the computer, Lawton tests whether different surgical techniques would alter blood flow enough to ease “hot spots” of pressure inside the aneurysm.
About 20 patients have had fusiform aneurysms modeled since the project began in 2002, and Lawton operates on about four a year — up from the one operation a year he’d gamble on before the modeling.
Spear’s aneurysm was so big that Lawton used an artery from her arm to reroute some blood to flow around it, and closed off another blood vessel feeding it. Her pain and other symptoms quickly disappeared, and brain scans last month show the aneurysm shrank from a round ball to a tube.
“He was being a daredevil to tackle it,” Spear says with a laugh. “I am so glad he gave me a second chance at life.”