One-third of all brain aneurysms rupture: The size is not a significant risk factor

May 22, 2014, University of Helsinki
Approximately one-third of all aneurysms and up to one fourth of small aneurysms will rupture during a patient's lifetime. Credit: Miikka Korja, University of Helsinki

The lifetime risk for rupture of a brain aneurysm depends heavily on the patient's overall load of risk factors. However, a recent study by researchers from the University of Helsinki and Helsinki University Central Hospital demonstrated that the size of an aneurysm has no great significance on the risk of rupture.

This is a unique study in that it monitored patients over their entire lifetimes, whereas typical follow-up studies last only between one and five years in duration. The study is also exceptionally broad in scope; Dr. Seppo Juvela points out that the only other place where a study of similar scope has been conducted is Japan.

"It is unlikely that another similar, non-selected lifetime follow-up study on aneurysm will ever be conducted again," he states.

Current care practices are based largely on the results of previous, shorter studies. Such studies have shown that the size of the aneurysm is the most significant factor predicting its risk for rupture. Consequently, small (<7mm) aneurysms have often been left untreated, even though such aneurysms have also been known to rupture and cause brain haemorrhages.

The new study established that approximately one third of all aneurysms and up to one fourth of small aneurysms will rupture during a patient's lifetime. The risk of rupture is particularly high for female smokers with brain aneurysms of seven millimetres or more in diameter. What surprised the researchers most was that the size of an aneurysm had little impact on its risk for rupture, particularly for men, despite a previously presumed correlation. In addition, the risk of rupture among non-smoking men was exceptionally low.

This video depicts microneurosurgical clipping of an unruptured intracranial aneurysm, which is arising from the bifurcation i.e. branching point of two right middle cerebral arteries. In brief, the aneurysm locates in this case between the frontal and temporal brain lobes, and therefore it can be reached by sharply cutting normal membranes between the frontal and temporal lobes. This microneurosurgical dissection opens a natural corridor leading to the aneurysm. One aneurysm clip occludes the neck of the aneurysm and the aneurysm cannot rupture anymore. The normal brain arteries are left patent. Operated by neurosurgeon, Associate Professor Miikka Korja Credit: Miikka Korja, University of Helsinki

"This is not to say that aneurysms in non-smoking men never rupture, but that the risk is much lower than we previously thought. This means treating every unruptured aneurysm may be unnecessary if one is discovered in a non-smoking man with low blood pressure," Juvela clarifies.

But why have previous studies not reached these same results if they are so obvious?

"It is difficult to conduct reliable epidemiological research in brain aneurysms. The past 10 years have seen a distortion in the field due to a very limited group of researchers determining the direction for research. Now the situation is clearly changing, and clinically reasonable, population-based studies using non-selected data are on the rise again," states Docent Miikka Korja of the HUCS neurosurgery clinic.

Finland has a strong tradition of studying the prevalence, risk factors and care of brain aneurysms, and the Helsinki University Central Hospital is one of the world's leading units to provide treatment for brain aneurysms. Major studies in the field published by Finnish researchers include the world's most extensive twin study on the hereditability of subarachnoid haemorrhage, the largest follow-up study on subarachnoid haemorrhages among diabetics, the most extensive study on the life expectancy of subarachnoid haemorrhage survivors and a study on the for subarachnoid haemorrhages using the most extensive population data.

Explore further: Growth in cerebral aneurysms increases risk of rupture

More information: The article will be published in Stroke 22 May, online. Juvela & al. "Lifelong rupture risk of intracranial aneurysms depends on risk factors - a prospective Finnish cohort study"

Related Stories

Growth in cerebral aneurysms increases risk of rupture

July 2, 2013
Cerebral aneurysms of all sizes—even small ones below seven millimeters—are 12 times more likely to rupture if they are growing in size, according to a new study published online in the journal Radiology.

Most common genetic heart valve abnormality associated with risk of aneurysm

May 14, 2014
The most common heart valve abnormality has now been linked to an increased risk of aneurysms.

Gene variant raises risk for aortic tear and rupture

April 17, 2014
Researchers from Yale School of Medicine and Celera Diagnostics have confirmed the significance of a genetic variant that substantially increases the risk of a frequently fatal thoracic aortic dissection or full rupture. ...

No increase in brain aneurysm rupture risk during pregnancy and delivery

February 7, 2013
For women with aneurysms involving the brain blood vessels, pregnancy and delivery don't appear to increase the risk of aneurysm rupture, reports a paper in the February issue of Neurosurgery, official journal of the Congress ...

Study sheds light on genetic factors for intracranial aneurysm

February 14, 2014
(Medical Xpress)—A large collaborative study that included researchers from the University of Cincinnati (UC) College of Medicine is reporting a new chromosomal region associated with intracranial aneurysm susceptibility, ...

Risk of rupture increases with size of cerebral aneurysm

June 28, 2012
(HealthDay) -- The natural course of unruptured cerebral aneurysms varies according to their size, location, and shape, according to a study published in the June 28 issue of the New England Journal of Medicine.

Recommended for you

A nanoparticle inhalant for treating heart disease

January 18, 2018
A team of researchers from Italy and Germany has developed a nanoparticle inhalant for treating people suffering from heart disease. In their paper published in the journal Science Translational Medicine, the group describes ...

Starting periods before age of 12 linked to heightened risk of heart disease and stroke

January 15, 2018
Starting periods early—before the age of 12—is linked to a heightened risk of heart disease and stroke in later life, suggests an analysis of data from the UK Biobank study, published online in the journal Heart.

'Decorated' stem cells could offer targeted heart repair

January 10, 2018
Although cardiac stem cell therapy is a promising treatment for heart attack patients, directing the cells to the site of an injury - and getting them to stay there - remains challenging. In a new pilot study using an animal ...

Two simple tests could help to pinpoint cause of stroke

January 10, 2018
Detecting the cause of the deadliest form of stroke could be improved by a simple blood test added alongside a routine brain scan, research suggests.

Exercise is good for the heart, high blood pressure is bad—researchers find out why

January 10, 2018
When the heart is put under stress during exercise, it is considered healthy. Yet stress due to high blood pressure is bad for the heart. Why? And is this always the case? Researchers of the German Centre for Cardiovascular ...

Heart-muscle patches made with human cells improve heart attack recovery

January 10, 2018
Large, human cardiac-muscle patches created in the lab have been tested, for the first time, on large animals in a heart attack model. This clinically relevant approach showed that the patches significantly improved recovery ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet May 23, 2014
Being a female who had an aneurysm rupture when I was 42, just want to say that I never smoked. However I had headaches all of my life and tried to tell doctors that I had something wrong. No one would listen.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.