Study By UB Neurosurgeons Finds That Cigarette Smoking Is Linked To Size Of Brain Aneurysms

BUFFALO, N.Y. -- Cigarette smoking appears to increase the risk for developing large brain aneurysms in patients who are predisposed to these life-threatening, blood-vessel malformations, a study headed by researchers in the University at Buffalo Department of Neurosurgery has shown.

Results published in a recent issue of the journal Neurosurgery show that in a multi-center study, 92 percent of patients with the aneurysms larger than 24 mm., and 78 percent with aneurysms ranging in size from 13 mm. to 24 mm were smokers. Sixty-six percent of patients with aneurysms smaller than 13 mm. were smokers.

"It is clear from our study that smoking leads to growth of larger aneurysms," said Lee R. Guterman, UB assistant professor of neurosurgery and senior author on the study. "This may be due to direct effects of the nicotine on the blood vessel wall or indirect effects like hypertension."

A brain aneurysm is a blood-filled, balloon-like structure that forms at a weak spot in the vessel caused by damage to the vessel lining. A ruptured aneurysm can kill instantaneously, and at the very least is a medical emergency. The larger the aneurysm, the greater the risk of rupture and the poorer the outcome.

Because aneurysm size is critical to survival and disability, and because little definitive information exists on what causes an aneurysm to be large or small, UB researchers set out to assess the relationship between aneurysm size and factors known to damage the brain's blood vessels.

The study group was composed of 298 patients in the placebo-treated group who took part in a 54-center clinical trial of a drug thought to decrease brain-cell damage in persons with bleeding aneurysms. The assesment of aneurysm size was conducted at UB and the University of Colorado in Denver.

Demographic, health and lifestyle data were collected from participants when they were admitted to the hospital. Of the 298 participants, 218 were women; 63 had large aneurysms.

Analysis of patient data with aneurysm size showed that smoking at any time was independently associated with large aneurysms. However, other known risk factors for cerebrovascular disease, including hypertension, diabetes and use of alcohol or illicit drugs, showed no relationship to aneurysm size.

In addition, patients with large aneurysms were:

• More likely to die within three months than those with small aneurysms

• More likely to have multiple aneurysms

• Lower functioning at admission

Guterman said cigarette smoking may contribute to large aneurysm size by promoting degradation of elastin in blood vessel walls. Elastin helps blood vessels retain their shape. If elastin has deteriorated, the vessel wall may be susceptible to expanding or ballooning at sites where blood flow is especially turbulent, such as the middle cerebral artery. Large aneurysms were found to be more prevalent at this location.

"These findings on the effect of cigarette smoking on aneurysm size, coupled with our earlier findings, suggest smoking predisposes individuals to multiple intracranial aneurysms," Guterman said. "The only way people may be able to prevent formation of large or giant aneurysms is to stop smoking. Patients with known unruptured small aneurysms should definitely stop smoking."

Also participating in the study from the UB Department of Neurosurgery were postdoctoral fellows Adan I. Quershi, M.D., and M. Fareed K. Suri, M.D., and L. Nelson Hopkins, M.D., department chair. University of Colorado researchers were Gene Y. Sung, M.D., and Robert Straw, Ph.D. The initial drug trial from which the study group was drawn was funded by Pharmacia & Upjohn.