How do you decide whether to treat a brain aneurysm or to use conservative management?

So what we tend to do is try to divide aneurysms into both size and location. Below a certain threshold, seven millimetres, we tend to be very conservative with aneurysms. That said, the location's important, so we tend to divide those aneurysms into either the anterior circulation or posterior circulation. The latter, the posterior circulation, carries a higher risk for size of future rupture.