A 78-year-old woman who had previously undergone prosthetic graft replacement of the total aortic arch was admitted to repair a chronic expanding type IIIb dissecting aneurysm. Firstly the patient's abdominal aorta was replaced with a prosthetic graft without any complications, then the thoracicdescending aorta was repaired five months later. Surgery for the thoracic descending aorta was performed with distal perfusion, cerebrospinal fluid drainage, somatosensory evoked potential (SEP) monitoring and reimplantation of three pairs of intercostal arteries. During surgery, SEP showed no significant changes, and the patient awoke without paraplegia three hours after the surgery. However, she developed bilateral complete paraplegia eight hours after the surgery. Reexploration demonstrated thrombo-occlusion of the sidearm graft for reimplantation of the Th10 intercostal artery. After thrombectomy of the sidearm graft, there was gradual neurological recovery and the patient was ambulatory when discharged. Quick treatment to restore the spinal cord blood supply promoted recovery from paraplegia.