The size of a brain aneurysm does not significantly affect the risk for rupture, according to a new Finnish study. About one-third of all brain aneurysms rupture during a patient’s lifetime, resulting in a brain hemorrhage. The risk tends to depend on the individual’s overall set of risk factors, with smoking playing a major role, particularly in women.
The study, conducted by researchers from the University of Helsinki and Helsinki University Central Hospital, monitored aneurysm patients their entire lives, compared to typical follow-up studies that last only between one and five years. The research is also particularly broad in scope.
“It is unlikely that another similar, non-selected lifetime follow-up study on aneurysm patients will ever be conducted again,” said neurosurgeon Seppo Juvela, M.D.
Currently, treatment is based largely on the findings of previous, shorter studies, which have claimed that the size of the aneurysm is the greatest factor in predicting risk for rupture. As a result, smaller aneurysms have gone untreated, even though these aneurysms have also been known to rupture and cause brain hemorrhages.
The new study confirmed that approximately one-third of all aneurysms and up to one-fourth of small aneurysms will rupture during a patient’s lifetime. The risk is especially great for female smokers with brain aneurysms of seven millimeters or more in diameter.
The biggest surprise in the study was that the size of an aneurysm had minimal impact on its risk for rupture, particularly for men, despite previous findings. Furthermore, the risk for rupture among non-smoking men was very low.
“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 said.
But why have previous studies come up with different conclusions?
“It is difficult to conduct reliable epidemiological research in brain aneurysms,” said Dr. Miikka Korja of the Helsinki University Central Hospital neurosurgery clinic. “The past 10-15 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.”
Source: University of Helsinki