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Aneurysms rare, but researchers search for what might trigger rupture

Only a small percentage of the population has a brain aneurysm, and most have no idea the blood vessel anomaly is lurking inside their skull.

In rare cases, aneurysms can rupture and cause bleeding around the brain — and one group of researchers suggests even some everyday activities could bring on that potentially fatal or neurologically debilitating event.

However, at least one leading Canadian neurologist has reservations about the findings and worries they could needlessly frighten patients with known aneurysms into changing their behaviour, even though their individual risk of rupture is tiny.

Writing in the Journal of the American Heart Association, researchers from the Netherlands determined a list of eight triggers of what’s called a subarachnoid hemorrhage, or bleeding at the base of the brain, arising from an aneurysm that has burst.

Topping their list of pre-rupture activities are coffee-drinking, followed by vigorous exercise and nose-blowing. Two more bodily functions round out the top five — having sex and straining to defecate.

“All of the triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture,” said Dr. Monique Vlak, lead author of the study and a neurologist at the University Medical Center in Utrecht, the Netherlands.

But Dr. Christopher Wallace, a neurologist at Toronto’s University Health Network who specializes in neurovascular conditions, said he’s concerned the findings will lead some people to believe that people with aneurysms “don’t have a life because no matter what they do they’ll die — and that’s just not true.”

To conduct the study, Vlak’s team had 250 patients fill out a questionnaire detailing their exposure to 30 potential trigger factors in the period shortly before their aneurysms burst, as well as the typical frequency and intensity of these activities. They then assessed which activities were likely precipitating events and their relative risk for causing a rupture.

“We wanted to know if those were actually trigger factors or just coincidental things that happened together,” Vlak said in an interview.

The researchers found that strenuous physical exercise, for instance, more than doubled the relative risk of aneurysmal rupture, while sexual intercourse raised that risk 11-fold.

While having enormous respect for research produced by the Netherlands group led by Dr. Gabriel Rinkel, Wallace believes results from this study — and the study’s design — have a number of weaknesses.

“There may be other completely unknown factors and probably are that are responsible for aneurysms ruptured, such as the structural integrity of the aneurysm or how thin the (artery) wall becomes or inflammation in the dome of the aneurysm.”

Purported triggers such as having sex or a difficult bowel movement could, in fact, be secondary or even entirely unrelated, he said.

“You could have hundreds of people with aneurysms and only two of them have had the inflammation or whatever it is, so only two of them out of a hundred need to watch their exercise or their coffee intake.”

Vlak said the findings aren’t meant to scare people away from normal activities or induce worry that they may have an aneurysm that could pop: only an estimated two to three per cent of people have a ballooned blood vessel in the brain; less than 10 in every 100,000 people in the population experience a hemorrhage from a ruptured aneurysm.

Some people find out they have an aneurysm incidentally, when it shows up on brain imaging performed for another neurological condition. Others may learn they have an aneurysm after seeking medical attention for severe pain, double vision and other symptoms caused by a large ballooned artery that is compressing nerves.

But most brain aneurysms are silent: the person has no idea there is a problem until it bursts, at which time they may experience some or all the following symptoms: a sudden, extremely severe headache; vomiting; neck stiffness; loss of consciousness; loss of function in one or more parts of the body; or a seizure.

And a ruptured aneurysm can be catastrophic if not treated quickly. An estimated 40 to 50 per cent of patients die from the bleeding into the brain, while roughly 20 per cent who survive are left with neurological deficits, some extremely severe.

“More than 40 per cent go home in good shape,” Wallace estimated.

Wallace said some people with known aneurysms do not need to have surgical repair. Some have malformations that are small and pose little risk of rupture, and for some older patients the procedure may pose a greater risk than the aneurysm itself.

“It’s important then not to drive fear into those individuals who have discovered an aneurysm and it may have been deemed not reasonable to treat them,” he said.

“I will not be changing my advice to patients based on this article. I don’t restrict (their activities) in any way shape or form.”

Vlak said the study was partly driven by patients with known aneurysms, some of them on waiting lists for surgical repair, and the researchers wanted to know what advice to give them about avoiding behaviours that might minimize their risk of rupture.