Effect of Post-Ischemic Hypothermia on Spinal Cord Damage induced by Transient Ischemic Insult in Rabbits

Objective: The effect of post-ischemic mild hypothermia applied immediately after induced transient ischemia on the extent of neuronal damage to the spinal cord was investigated in rabbit. Subjects and Methods: A 15-minute period of transient abdominal aortic occlusion for spinal cord ischemia at a rectal temperature of 37.3 ± 0.3°C was performed just below the left renal vein via median laparotomy. Three groups of rabbits were investigated; Group 1 (n = 8) subjected to ischemia and reperfused at the same temperature for 7 hours, Group 2 (n = 8) also subjected to ischemia and then to 6 hours of systemic hypothermia (32.5 ± 0.5°C), and Group 3 (n = 8) non-ischemic controls. All the rabbits in Group 1 and Group 2 were sacrificed at 1 week after ischemic injury. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage. Results: The mean modified Tarlov's score at 1 week after ischemic injury was 0.5 ± 0.8 in Group 1, whereas it was 4.4 ± 1.4 (p <.001) in Group 2. The mean total number of surviving neurons within examined sections of the spinal cord was significantly greater in Group 2 than in Group 1 (Group 1: 8 ± 66.1 vs Group 2: 300.9 ± 154.1, p <.001). Conclusions: Post-ischemic hypothermia induced immediately after reperfusion significantly reduced ischemia-induced neuronal damage in rabbit.