Good question @deanatay!
Welcome to Connect. Have you had any treatment?

Hi, @deanatay. I took your question to Dr. Freeman. His answer is below:
This depends on whether the aneurysm is ruptured or not. If ruptured, the treatment would be surgery. If unruptured, 3mm aneurysms are typically monitored or observed since the risk of surgery/intervention can outweigh the short-term/long-term benefits. Aneurysms of 5mm are more likely to be treated surgically, and it depends on the growth rate. Mayo Clinic conducted the ISUIA trial (International Study of Unruptured Intracranial Aneurysm in the New England Journal of Medicine http://www.nejm.org/doi/full/10.1056/NEJM199812103392401#t=article ).
A good rule of thumb for patients is that aneurysms 7mm or greater become greater risk for those carotid aneurysms (ie., ‘behind the eye’), whereas those 4mm or greater in the back of head region (called PCOM, PCA, etc) should be considered for treatment. Those less than 7mm of the carotid should be carefully discussed with their surgeon since this ISUIA should be carefully decided and on other indivualized risk factors, such as age, growth rate, comorbidities and other important factors.
Finally some aneurysms behind the eye are within the cavernous sinus, which is potentially less risky to fix with a newer ‘flow diversion technology’ but again, patients are encouraged to talk about the ‘risk vs. benefit and alternatives’ with their doctors. Mayo Clinic has experts in all these areas and were principle investigators of the ISUIA trial.
Also a recent study lead by Dr Robert D Brown at Mayo and other international investigators called PHASES can help decide in this matter (http://thelancet.com/journals/laneur/article/PIIS1474-4422(13)70263-1/fulltext).