NEWS BRIEFS: Brain Aneurysm Symptoms Depends on Size and Site of Aneurysm

Friday, September 07, 2001

Mayo Clinic researchers have provided the first data on aneurysm characteristics, clinical symptoms and survival rates among people with intracranial aneurysms in a defined population.

Published in the August 2001 issue of Neurosurgery, the Mayo Clinic researchers found that most aneurysms were detected in the study group — patients in Olmsted (Minn.) County from 1965 to 1995 — by a symptom, such as an intracranial hemorrhage.

Bleeding into the brain tissue was the most common symptom (60 percent of the 270 patients and 86 percent of the patients who exhibited symptoms). Other symptoms included lack of function in a nerve supplying the head or neck, transient ischemic attacks and seizures. The nature of the symptoms depended on the size of the aneurysm, and its location in the brain. About one in five people with an aneurysm had more than one aneurysm.

"Brain aneurysms are present in at least 1 percent of the population, so over 3 million Americans have a brain aneurysm," says Robert Brown, M.D., a Mayo Clinic neurologist and senior author for the study. "Studies performed in a population such as this provide clarify our understanding of how frequent aneurysms cause symptoms, the nature of the aneurysms that occur, and also provide information that can be compared to other multiple-medical center type studies."

Twenty-three percent of the patients who had bleeding into the brain caused by the aneurysm died within one day after aneurysm diagnosis, compared with five percent of those who did not exhibit symptoms or exhibited symptoms but without intracranial hemorrage. At five years, 44.7 percent of patients with hemorrhage had died compared with 29.4 percent of patients with symptoms other than hemorrhage.

After the first 24 hours after detection of the aneurysm, survival rates did not differ significantly for those presenting with or without hemorrhage. Predictors of better survival also included younger age and later calendar year of presentation, implying that survival after brain aneurysm hemorrhage was improving over time.

Contact: Lisa Copeland at 507-538-0844 (days) Mayo Clinic External Relations 507-284-5005 (days) 507-284-2511 (evenings) email: newsbureau@mayo.edu

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