An aneurysm is the enlargement of an artery caused by weakness in the arterial wall. Often there are no symptoms, but a ruptured aneurysm can lead to fatal complications. An aneurysm refers to a weakening of an artery wall that creates a bulge, or distention, of the artery. Aneurysms often occur in the aorta, brain, back of the knee, intestine or spleen. A ruptured aneurysm can result in internal bleeding and stroke. It can sometimes be fatal. Aneurysms often have no symptoms until they rupture. Treatment varies from watchful waiting to emergency surgery. The choice depends on the location, size and condition of the aneurysm. Aneurysms have a variety of causes including high blood pressure and atherosclerosis, trauma, heredity, and abnormal blood flow at the junction where arteries come together. Although the exact cause of an aneurysm is unclear, certain factors contribute to the condition. For example, damaged tissue in the arteries can play a role. The arteries can be harmed by blockages, such as fatty deposits. These deposits can trigger the heart to pump harder than necessary to push blood past the fatty buildup. This stress can damage the arteries because of the increased pressure. Mycotic aneurysms are caused by infections of the artery wall. Tumors and trauma can also cause aneurysms to form.