<prompt> After doing a graft repair of a thoracoabdominal aneurysm, the patient developed weaknesss in both legs. Most probable cause for this is:Decreased blood supply to the lower limbsThoracosplanchnic injuryDiscontinuation of aeria radicularis magnaLumbosacral nerve injury  <response>: Ans is c i.e. Discontinuation of aeria radicularis magna The Aeria Radicularis Magna aery of Adamkiewicz is the main source of blood supply to the anterior spinal aery in the thoracolumbar segment of the spinal cord. It arises from either one of the lower posterior intercostal aeries T9-11, or of the subcostal aery T12, or less frequently of the upper lumbar aeries L1 and L2. Its occlusion or interruption is one of the major reasons for spinal cord ischemia leading to paraparesisparaplegia during surgery for thoracoabdominal aneurysm. Clamping the descending thoracic aoa causes ischemia of the spinal cord and abdominal viscera. Clinically significant manifestations of hepatic, pancreatic, and bowel ischemia are relatively uncommon. However, both acute renal failure and spinal cord injury resulting in paraplegia or paraparesis remain major causes of morbidity and moality after these operations.- Schwaz 9e p678 Surgery to repair thoracic and thoracoabdominal aoic aneurysms is the most common cause of spinal cord infarction. Rates of spinal cord ischemia following thoracic aoic surgery have been repoed to be as high as 29 percent, but are more usually repoed as 10 to 11 percent. Both open surgery and endovascular repair are associated with spinal cord ischemia... Many factors may play a role in this complication. These include systemic hypotension, before, during, or after the procedure; aoic cross clamping causing decreased aerial perfusion and increased spinal canal pressure; and occlusion of impoant feeding aeries such as the aery of Adamkiewicz or other intercostal aeries either by ligation, resection, or embolization. - Spinal cord infarction: Vascular anatomy and etiologies Authors Michael Mullen, MD at uptodate.com Kieffer et al. 20 performed preoperative spinal cord aeriography in patients with thoracic and thoracoabdominal aneurysms, and identified the aeria radicularis magna ARM in 85. They repoed that the risk of paraplegia was 5 if the ARM was identified preoperatively and reimplanted, whereas it was 50 if the ARM was not reattached. - Spinal Cord Protection During Thoracoabdominal Aneurysm Repair Koichi Tabayashi at uptodate.com Occlusion of the aeria radicularis magna can cause spinal-cord ischemia with subsequent paraplegia. - Ischemic transverse myelopathy after endovascular repair of a thoracic aoic aneurysm. Reicha M, Balm R, J Endovasc Ther. 2001 Jun:83:321-7. 