Regional lidocaine infusion reduces postischemic spinal cord injury in rabbits

Paraplegia secondary to spinal cord ischemia is a devastating complication in operations on the descending and thoracoabdominal aorta. We hypothesized that the tolerance of the spinal cord to an ischemic insult could be impro ved by means of regional administration of lidocaine. Thirty-one New Zealan d white rabbits were anesthetized and spinal cord ischemia was induced by t he placement of clamps both below the left renal vein and above the aortic bifurcation. The animals were divided into 5 groups. Aortic occlusion time was 20 minutes in Group 1 and 30 minutes in all other groups. Groups 1 and 2 functioned as controls. Lidocaine (Group 5) or normal saline solution (Gr oup 3) was infused into the isolated aortic segment after cross-clamping. G roup 4 animals received 20% mannitol regionally, before and after reperfusi on. Postoperatively. rabbits were classified as either neurologically norma l or injured (paralyzed or paretic). Among controls, 20 minutes of aortic o cclusion did not produce any neurologic deficit (Group 1: 0/4 injured), whi le 30 minutes of occlusion resulted in more consistent injury (Group 2: 6/8 injured). Animals that received normal saline (Group 3) or mannitol (Group 4) regionally showed 80% neurologic injury (4/5), Animals treated with the regional lidocaine infusion (Group 5) showed much better neurologic outcom es (7/9 normal: 78%). This superiority of Group 5 over Groups 2, 3, and 4 w as significant (P <0.02). We conclude that regional administration of lidoc aine reduced neurologic injury secondary to spinal cord ischemia and reperf usion after aortic occlusion in the rabbit model.