Chronic aortic aneurysms are permanent and localized dilations of the aorta that remain asymptomatic for long periods of time but continue to increase in diameter before they eventually rupture. Left untreated, the patients’ prognosis is dismal, since the internal bleeding of the rupture brings about sudden death. Although successful treatment cures the disease, the risky procedures can result in paraplegia from spinal cord ischaemia or even death, particularly for aneurysms extending from the thoracic to the abdominal aorta and thus involving many segmental arteries to the spinal cord, i.e. thoracoabdominal aortic aneurysms of Crawford type II. Although various strategies have achieved a remarkable decrease in the incidence of paraplegia, it is still no less than 10 to 20%. However, it has been found that the deliberate occlusion of the segmental arteries to the paraspinous collateral network finally supplying the spinal cord does not increase rates of permanent paraplegia. A therapeutic option, ‘minimally invasive segmental artery coil embolization’ has been devised which proceeds in a ‘staged’ way to occlude groups of arteries under highly controlled conditions after which time must be allowed for arteriogenesis to build a robust collateral blood supply. PAPA-ARTiS is a phase II trial to demonstrate that a staged treatment approach can reduce paraplegia and mortality dramatically. It can be expected to have both a dramatic impact on the individual patient's quality of life if saved from a wheelchair, and also upon financial systems through savings in; 1) lower costs in EU health care; 2) lower pay-outs in disability insurance (est. at 500k in Year 1), and; 3) loss of economic output from unemployment. Approx. 2500 patients a year in Europe undergo these high risk operations with a cumulative paraplegia rate of over 15%; therefore >100M per year in costs can be avoided and significantly more considering the expected elimination of type II endoleaks.