what is aneurysm caused by
Overview. An aneurysm is a weak spot in the wall of a blood vessel that may cause an abnormal bulge. The bulge can rupture and cause internal bleeding. Although it can occur in any blood vessel, aneurysms are most common in the brain, the aorta, the legs, and spleen.n aneurysm is a weak spot in the wall of a blood vessel that may cause an abnormal bulge. The bulge can rupture and cause internal bleeding. Although it can occur in any blood vessel, aneurysms are most common in the brain, the aorta, the legs, and spleen.