Untreated or unrecognized they can be fatal due to dissection or "popping" of the aneurysm leading to nearly instant death.

The principal causes of death due to thoracic aneurysmal disease are dissection and rupture.

[citation needed] There are a number of causes,[3] Aneurysms in patients younger than 40 usually involve the ascending aorta due to a weakening of the aortic wall associated with connective tissue disorders like the Marfan and Ehlers-Danlos syndromes or congenital bicuspid aortic valve.

[7] However, average values vary with age and size of the reference population, as well as different segments of the aorta.

[citation needed] Open surgical repair remains the gold standard for thoracoabdominal aortic aneurysm treatment, particularly in patients with connective tissues disease.

Rates of postoperative spinal cord ischaemia can be kept at low levels after open surgical repair with the adequate precautions and perioperative maneuvers.