Ischemic preconditioning does not improve neurological recovery after spinal cord compression injury in the rat

Ischemic preconditioning (IPC) has been defined as the endogenous cellular protective mechanism evoked by brief ischemic periods. IPC renders the tissue of the central nervous system more resistant to subsequent lethal ischemic insults, and similar protective effect of IPC has been observed after experimental traumatic brain injury. Spinal cord trauma differs from cerebral trauma in that the secondary processes are damaging mostly the white matter. In the present study, we have tested the hypothesis that a transient non-lethal ischemic insult would improve outcomes after subsequent traumatic spinal cord injury (SCI). In the IPC group, 5-min spinal cord ischemia has been induced by aortic occlusion combined with hypotension. Forty-eight hours after IPC, moderate spinal cord injury has been induced by epidural balloon inflation at T8 level. Control group underwent identical surgical procedures without ischemia followed by SCI after 48 h. During the 4-week survival, locomotor performance of all rats was repeatedly tested and evaluated according to BBB scale. After 4 weeks, the animals were perfusion-fixed for histopathology, and morphometric analyses were performed in order to quantify the extent of the spinal cord lesion. All animals were completely paraplegic after SCI, and showed partial neurological recovery during their survival period. No significant differences were detected either in neurological scores or in morphometric measurements after 4 weeks' survival. These results indicate that in contrary to cerebral trauma, IPC does not improve the outcome after SCI.