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 ± 3.8 kg). SA pairs from T3 through L5 were serially sacrificed at 32 °C; SCPP and function - using motor-evoked potentials (MEPs) -were continuously monitored until 1 h 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 1 h, reaching its lowest point -19 ± 4 - after 5 h. Postoperatively, SCPP recovered to 33 ± 6 at 24 h; 42 ± 10 at 48 h; 56 ± 14 at 72 h; 62 ± 15 at 96 h, returning to baseline (63 ± 20) at 120 h. 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 °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 24-48 h may allow routine complete preservation of normal cord function despite sacrifice of all SAs.