A saccular aneurysm is the most common type of aneurysm and account for 80% to 90% of all intracranial aneurysms and is the most common cause of no traumatic subarachnoid hemorrhage (SAH). It is also known as a "berry" aneurysm because of its shape. The berry aneurysm looks like a sac or berry forming at the bifurcation or the "Y" segment of arteries. It has a neck and stem. These small, berry-like projections occur at arterial bifurcations and branches of the large arteries at the base of the brain, known as the Circle of Willis.
Fusiform aneurysm is a less common type of aneurysm. It looks like an outpouching of an arterial wall on both sides of the artery or like a blood vessel that is expanded in all directions. The fusiform aneurysm does have a stem and it seldom ruptures.
