Need Info: Which brain aneurysm locations are the most dangerous?

I’m wondering if some brain aneurysm locations are more vulnerable to rupture than others. Mine is 4.4 on the basilar artery. Is this artery particularly vulnerable? I read that somewhere that it is but don’t know if that’s really true. It’s got me worried.

I don’t know the answer to this, unfortunately, but I also would like to know :slight_smile:

Hey Msussman,
From my understanding there are many, many variables here. Vascular health (Health of the vessels), blood pressure, diet, stress, smoker/non smoker, family history, age, etc are just some of the variables that can go along with location. Size is also a very important consideration. Some medicos are of the opinion that if it is less than 10mm the risk is small BUT if the type of BA is saccular and the vessel wall is thin then the risk can be increased. So it often is not just a simple case of location that equates to an individuals vulnerability.
I have a family member that required an CT of their skull for a completely different diagnosis to unsuspectingly find a BA. They had no symptoms to suggest an issue. Some people can go their whole life having a BA without knowing, others can have symptoms from what is medically defined as insignificant in size but cause no end of issues (with symptoms often labelled psychosomatic). Some can have multiple BA’s where others can have a single one.
So, it really can be a whole list of contributing factors that can be used to assess an individuals vulnerability and not just location.

Hope it helps
Merl from the Moderator Support Team

Look up the International Subarachnoid Aneurysm Study I (ISAT I) completed and the ongoing ISAT II. The ISAT I had 2143 subjects in the study. It lists the numbers and placements of different aneurysms. The ISAT II papers just explain what they’re looking for as the study isn’t completed. Both are concerning ruptures

I had mine rupture back in 2011 and it was on the Basilar artery. I had it clipped and was out of the hospital and back to work about 2 weeks later. I did have some terrible headaches prior to the rupture but my GP passed it off as my allergy meds causing it at the time. I would tend to think any aneurysm is dangerous and should be looked at by your Dr. but as to the location and which is worse…that would have to come from him/her.

My first neurologist, around 60 years old, refused to perform a clipping because it was too deep inside my brains.
A year later a younger, around 30, neurologist was appointed to my case and the surgery went great.
Too deep inside potentially increase danger.
If I’m not mistaken, 4.4 is borderline.
PS. Check on line.

Peter, Where in your head were the headaches that were a warning about your basilar artery aneurysm? I have had a chronic head in the back of my skull and temples for almost two weeks. Only moderate pain, but ongoing and it doesn’t respond OTC meds. I contacted my neurologist, but I am wondering if this type of headache as anything to do with my aneurysm. Thoughts?

Merl, Thank you for the detailed reply! Everything alarms me, as my aneurysm was an “incidental” finding when I ended up in the ER a few months ago with a horrible headache that was later diagnosed as a migraine. Migraine or not, I now know there is aneurysm and I’m trying to sort through everything.

Hey Msussman,
“Everything alarms me…” And that is normal. Initially, every ache, every pain and I was ready to hit the panic button but over time I have been able to learn and identify a ‘normal’ pain from a ‘time to act’ pain, which usually for me involves a progression of symptoms. Now I say ‘normal’ because it’s far from what I would have previously considered normal, prior to surgery. But since my first neurosurgery my whole comprehension level of pain has changed. What I would now consider a 5 on a scale of 0-10 previously would have been in excess of 10, since surgery I have headaches daily, most being greater than 5, some days 8 or 9. But for me if I find that I’m having visual disturbances, nausea and often temperature fluctuations, in combination, it’s time to act.
That ‘sort through everything’ emotion can be a real trial but slowly we do learn our own signs, they are all very individual. Some people will come out with lines such as “Oh I get headaches like that too…” and although they are trying to be helpful, in reality, it’s not very helpful at all. But you will learn your own signs and how best to manage it all for yourself.

Merl from the Moderator Support Team



Oh boy do I agree with everything Merl has said. I laugh when they say rate your pain now. With it being personal, then they give you a look. My retort is I’m basing it on foot surgery, back surgery and SAH; what are you basing it on? For headaches, its all about symptoms progression, perspective and experience. Your doctor would be a great place to start on what they think is the worry now symptoms. Give them a call!

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I have to agree with Moltroub "…what are you basing it on? " He states “…I laugh when they say rate your pain now…” I do NOT laugh, in fact I find it very frustrating. When you hurt your arm it affects your arm, when it’s your head it affects EVERYTHING. Post surgery, I had a nurse ask for my pain rating and I said 15. Her response was “Ohh it can’t be that bad” I told her to lay on the floor and I’d kick her in the side of the head and she could tell me her pain rating. She was offended, but no where near as offended as I was by her statement.
Pain is very subjective. If the worst pain you have ever had is a sprained ankle then that is as far as your pain rating/experience would range and that is why I previously stated ‘What I would now consider a 5 on a scale of 0-10 previously would have been in excess of 10’, we can only use such a rating from past experience. So trying to express pain on a rating scale is near on impossible IMO.

Merl from the Moderator Support Team

Pain level really is subjective and the medical field needs to remember they are asking our perspective of pain, not theirs. That’s why I laugh. I should have said sarcastically laugh. I do on occasion ask what they think is my pain level just to remind them its my perspective not theirs that we are discussing, especially when they come up with the “Ohh it can’t be that bad”.

Everything I’ve read say the posterior communicating artery have the highest risk of rupture even at a smaller size annie, and then the anterior communicating artery is second most likely to rupture at a smaller size.

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You can’t really rely on which artery, but what your underlying health is. No smoking and no hypertension are considered protective. Weight lifting and constipation must be avoided, I was told. Big aneurysms are more likely to rupture. And, age is a factor in risk.
A single medical study isn’t seen as proof by anyone. But, A huge study reported in the medical journal, Lancet, looked at the 5-year cumulative rupture rates for patients who did not have a history of hemorrhage. Size was crucial. Rupture rates were reported and I’m quoting here from the abstract that is online. The risk rate was as low as 0% for small anterior aneurysms. The size was much more predictive than the location.
“4060 patients were assessed…5-year cumulative rupture rates for patients who did not have a history of subarachnoid hemorrhage with aneurysms located in internal carotid artery, anterior communicating or anterior cerebral artery or middle cerebral artery were 0%, 2·6%, 14·5%, and 40% for aneurysms less than 7 mm, 7–12 mm, 13–24 mm, and 25 mm or greater, respectively, compared with rates of 2·5%, 14·5%, 18·4%, and 50%, respectively, for the same size categories involving posterior circulation and posterior communicating artery.”
So, posterior aneurysms are slightly, very slightly, more likely to rupture than anterior arteries, but size was the most important factor for either anterior or posterior arteries.
My advice is to listen to your medical team about whether the risks of intervention are greater than the risks of monitoring.
Most people have signs of heart disease, kidney disease, liver disease, and other damaged organs as we age, but intervention is only needed when the risks are larger than not intervening. When it comes to brain care, I wish intervention had not been necessary, because you aren’t ever the same after your skull has been opened. Listen to your docs and get a second opinion if you have doubts.


Thanks for sharing.