Trauma. Lefort / orbital fractures. SAH
Do u see anything other than the aneurysm?
Note spasm of the supraclinoid ICA as well as A1 (dashed arrow) Note another anatomical point — in contrast to nontraumatic saccular aneursyms, which usually arise at branch points, the traumatic ones do not have any predilection for or against branches. They happen to be where they happen to be. In this case, the Superior Hypophyseal Artery (arrow) is below the aneurysm. See Superior Hypophyseal Artery page for a lot of info on this interesting artery.
Again, notice anything other than aneurysm?