Reappraisal of surgical treatment of traumatic transection of the thoracic aorta. Since Crawford's report in 1973, repair of traumatic transection of the thoracic aorta without shunt or bypass has emerged as a popular technique which simplifies the operation and avoids use of heparin. Growing evidence, however, indicates that the incidence of paraplegia is higher with this method and may outweigh its advantages. With this in mind, we have examined our experience with 40 patients who underwent repair of aortic transection from 1975-1988. The operated patients in our series all survived. Fourteen were repaired using some type of bypass or shunt, none of whom developed paraplegia. The remaining 26 patients were repaired without a shunt and 9 (34.6%) developed paraplegia or paraparesis (p less than 0.02). Paraplegia was related to aortic occlusion time (p less than 0.002). It did not occur in 11 patients with times less than 27 minutes, but happened in 2 of 8 patients with times between 28 and 35 minutes and in all 7 patients with clamp times over 35 minutes. These data suggest that shunt or bypass should be used in most cases of aortic transection. 