Spinal cord blood flow in response to focal compression

Anesthetized sheep were subjected to spinal cord compression to 200 mm Hg at T13 by means of a distensible epidural balloon. Eight animals were subjected to compression for 20 min, 10 animals for 40 min, and 12 animals for 80 min. Spinal cord blood flow (SCBF) and spinal evoked potentials (SEPs) from L7 to C7 and vice versa were measured prior to, during, and 1/2, 1 1/2, 2 1/2, and 3 1/2 h following compression. The traumatized zone manifested a hyperemic response subsequent to balloon withdrawal in the 20-min and 40-min groups. In the 80-min group, SCBF returned to baseline. With compression, SEPs were obliterated in all animals and failed to recover after 3 1/2 h following injury, irrespective of the duration of compression. These results show that reperfusion of the cord following a compressive insult is not accompanied with recovery of SEPs.