Spinal cord perfusion after extensive segmental artery sacrifice: can paraplegia be prevented?

OBJECTIVE: Understanding the ability of the paraspinal anastomotic network to provide adequate spinal cord perfusion pressure (SCPP) critical for both surgical and endovascular repair of thoracoabdominal aortic aneurysms (TAAA). METHODS: To monitor pressure in the collateral circulation, a catheter was inserted into the distal end of the divided first lumbar segmental artery (SA) of 10 juvenile Yorkshire pigs (28.9+/-3.8kg). SA pairs from T3 through L5 were serially sacrificed at 32 degrees C; SCPP and function - using motor-evoked potentials (MEPs) - were continuously monitored until 1h after clamping the last SA. Intermittent aortic and SCPP monitoring was continued for 5 days postoperatively, along with evaluation of motor function. RESULTS: A mean of 14.4+/-0.7 SAs were sacrificed without loss of MEP. SCPP (mmHg) dropped from 68+/-7 before SA clamping (77% of aortic pressure) to 22+/-6 at end clamping, and 21+/-4 after 1h, reaching its lowest point - 19+/-4 - after 5h. Postoperatively, SCPP recovered to 33+/-6 at 24h; 42+/-10 at 48h; 56+/-14 at 72h; 62+/-15 at 96h, returning to baseline (63+/-20) at 120h. Despite comparable SCPP patterns, four pigs did not fully regain the ability to stand. Six animals recovered: two could stand and four could walk. CONCLUSIONS: Interruption of all SAs at 32 degrees C in this pig model results in a spectrum of cord injury, with normal function in a majority of pigs postoperatively. The short duration of low SCPP suggests that hemodynamic manipulation lasting only 24-48h may allow routine complete preservation of normal cord function despite sacrifice of all SAs.