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June 2009 Issue

Joseph Broderick, MD
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Genetic Variations May Give Clues to Intracranial Aneurysms

Published June 2009

Small unruptured intracranial aneurysms rarely require surgical or endovascular interventions, with doctors preferring instead to manage them medically by urging patients to quit smoking or to control their blood pressure.

New information from a team that includes UC researchers, however, indicates that patients with a family history of intracranial aneurysm (an abnormal bulging outward of one of the arteries in the brain) have a 17 times greater rate of rupture than those without such a history and that their aneurysms may therefore need to be managed more aggressively through surgery or endovascular intervention.

The study, led by Joseph Broderick, MD, chair of the neurology department at UC, was presented at the American Stroke Association International Stroke Conference in San Diego this past spring and published online in the journal Stroke. It appears in this month’s print edition.

Researchers examined magnetic resonance angiographies (MRA) of 548 subjects from the international Familial Intracranial Aneurysm study with a strong family history of intracranial aneurysm who also had a history of smoking or hypertension but no known intracranial aneurysm.

(Because of MRA’s high cost, screening was limited to those subjects who were smokers or who had hypertension because they were considered to have the highest likelihood of an unruptured intracranial aneurysm.)

Of those 548, 113 (20.6 percent) were found to have an unruptured intracranial aneurysm—all but five were smaller than 7 millimeters. From those 113, the annual rupture rate was determined to be 1.2 percent.

That’s approximately 17 times higher than the annual rupture rate for subjects with an unruptured intracranial aneurysm of similar size and no family history of intracranial aneurysm in the International Study of Unruptured Intracranial Aneurysm (0.069 percent).

“This changes the equation that physicians use to make decisions about whether or not they should clip or coil aneurysms,” says Broderick, research director of the UC Neuroscience Institute.

Both clipping (isolating an aneurysm from normal circulation via a surgical procedure) and coiling (a minimally invasive procedure that accesses the aneurysm from within the bloodstream) carry potential risks, particularly in older patients, so physicians have historically managed small aneurysms medically by controlling hypertensions and/or counseling the patient to quit smoking.

With this new information, Broderick says, “We should be thinking more strongly about clipping or coiling small aneurysms in patients with a family history of intracranial aneurysm, because their aneurysms are more likely to rupture if left untreated.”

Broderick recommends some type of brain imaging for patients with a family history of intracranial aneurysm, particularly if they smoke or have hypertension. And if they do smoke, they should quit as soon as possible.

“That’s one thing people can do right away,” Broderick says. “Otherwise, it’s like putting a gun to your head and clicking the trigger until it goes off.”

The study was funded by a grant from the National Institute of Neurological Disorders and Stroke.
UC co-authors include Matthew Flaherty, MD, Richard Hornung, DrPH, Dawn Kleindorfer, MD, Charles Moomaw, PhD, Laura Sauerbeck and Daniel Woo, MD.

Other co-authors include Robert Brown Jr., MD, John Huston III, MD, and Irene Meissner, MD, of the Mayo Clinic; Craig Anderson, MD, of the George Institute for International Health, University of Sydney; Guy Rouleau, MD, PhD, Notre Dame Hospital, Montreal; Tatiana Foroud, PhD, Indiana University School of Medicine; and E. Sander Connolly, MD, Columbia University. 

For more information about UC research on aneurysms, visit

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