If you poke around looking for trouble, eventually you're going to find something.

May 20, 2010 6:30 PM

Short and sweet: Can anyone help me find statistics on the chances of a brain aneurysm rupturing, given it's size?

I recently had another cerebral MRI done. In the good news department, it seems like the giant blockage in my left size of my brain hasn't changed, and my neuro has given me a clean bill of health, at least on this particular failing of my cerebral arteries. Yay! As long as I don't do anything stupid, it shouldn't be affecting my life anymore. Except, you know, for these damn headaches. But we're dealing with those.

But... they found an itsy bitsy teeny weeny aneurysm. 1.6 mm, to be exact. We'd normally have no clue it was there, except for the fact that they're poking around looking checking up on my other issues and it happened to be seen. Apparently in the aneurysm-classification world, anything <10mm is considered small, and my neuro considers anything <2mm "tiny". They just want me to come in for another MRI in the next 3-4 years, to make sure it's not getting any bigger. They don't consider surgery for anything <10mm, because the chances of rupture are so significantly less than the surgery risks.

My question is -- what are those chances of rupture? I've been googling, and perhaps my google-fu is failing me today, but I can't find any exact numbers.

I'm merely curious -- it's not like the numbers I find are going to freak me out or anything. I asked my neuro, he didn't know off hand, except to say "tiny". I'm pretty sure the chances of me getting run over by a bus during any particular year, for example, are significantly higher. And I have faith in my brain's arteries - they may be flawed, but they've showed remarkable resiliency and the ability to fix problems themselves. I just like numbers.

Can anyone help me find those numbers?

posted by cgg to Health & Fitness (3 answers total)

Best answer: A 2003 article in the Lancet that studied 4060 patients found that "5-year cumulative rupture rates for patients who did not have a history of subarachnoid haemorrhage with aneurysms located in internal carotid artery, anterior communicating or anterior cerebral artery, or middle cerebral artery were 0% for aneurysms less than 7 mm." They also found that the rate was 2.5% for aneurysms in the"posterior circulation and posterior communicating artery."

Wiebers DO, Whisnant JP, Huston J III, Meissner I, Brown RD Jr, Piepgras DG, Forbes GS, Thielen K, Nichols D, O'Fallon WM, Peacock J, Jaeger L, Kassell NF, Kongable-Beckman GL, Torner JC. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. 2003;362:103–110.

A very recent article, cited below, claims that more important than absolute size is the ratio between the size of the aneurysm and the size of the artery where it is located.

Ma D, Tremmel M, Paluch RA, Levy EI, Meng H, Mocco J. Size ratio for clinical assessment of intracranial aneurysm rupture risk. Neurol Res. 2010 Jan 21. [Epub ahead of print]

My search of PubMed found a bunch of articles that commented on the difficulty of predicting aneurysm ruptures and the need for further research. Let me know if you want pdfs of any of these and I'll email them to you.
posted by vytae at 7:08 PM on May 20, 2010 [1 favorite]

Best answer: The Lancet article referenced by vytae is the most definitive study on this subject. MeMail me if you would like to read the original and can't access it.
posted by drpynchon at 7:56 PM on May 20, 2010

Publicly-funded research should be public. Here is a copy of the referenced Lancet article. Be well.
posted by killdevil at 10:07 PM on May 20, 2010