Monitoring of motoneuron activity for spinal cord ischemia

电刺激胫神经后在足底区域记录的F波/多突触反应复合体（FPC）是反映脊髓L-5水平前角细胞兴奋的一组电位。我们在实验和临床上评价了FPC在胸主动脉手术中对脊髓缺血监测的实用性。24只狗在戊巴比妥麻醉下接受了远端胸主动脉和左乳内动脉的球囊导管闭塞。一半的狗没有肌肉松弛剂，另一半是与非去极化肌肉松弛剂，泮库溴铵。即使使用肌松剂，也能很好地监测FPC，并且在所有犬中完成球囊动脉闭塞后3分钟内FPC均丢失。根据FPCs丢失后动脉闭塞时间分为A、B、C、D四组，分别为20、30、40、50 min。截瘫发生率A组为0%（0/6），B组为33%（2/6），C组为83%（5/6）（A vs C：P<0.01），D组为100%（6/6）。手术采用临时转流或部分体外循环。7例主动脉阻断或肋间动脉结扎后FPCs丢失。3例主动脉重建术后超过20 min的患者中有2例发生截瘫或下肢轻瘫，结论：FPC监测是检测脊髓缺血的有效方法，FPC丢失后20 min内重建脊髓血流可预防术后几乎完全截瘫。

The F-wave/polysynaptic responses complex (FPC) which is recorded on a plantar region after electric stimulation of the tibial nerve is a group of potentials reflecting the excitement of the anterior horn cells at the L-5 level of spinal cord. We evaluated the utility of FPC monitoring for spinal cord ischemia in the context of thoracic aortic surgery, experimentally and clinically.Twenty four dogs were subjected to the balloon catheter occlusion of both the distal thoracic aorta and the left internal mammary artery under pentobarbital anesth esia. Half of the dogs were treated with no muscle relaxants and the other half were with a non-depolarizing muscle relaxant, pancuronium. The FPCs were well monitored even if the muscle relaxant was used and were lost within 3 minutes after the completion of the balloon arterial occlusion in all dogs. They were divided into four groups, A,B,C, and D, according to arterial occlusion time after the loss of the FPCs, 20,30,40, and 50 minutes, respectively. Incidence of paraplegia was 0% (0/6) in Group A, 33% (2/6) in Group B, 83% (5/6) in Group C (A vs C : P<0.01), and 100% (6/6) in Group D.The FPCs were monitored in 13 patients who underwent graft replacement for thoracic or thoracoabdominal aortic aneurysms. The operations were performed with temporary bypass or partial cardiopulmonary bypass. The FPCs were lost in 7 patients after aortic clamping or intercostal artery ligation. Paraplegia or paraparesis occurred in two of three patients that aortic reconstruction was completed in beyond twenty minutes after the loss of the FPCs.In conclusion, FPC monitoring is a usefull method for detection of spinal cord ischemia and reconstruction of the spinal cord blood flow within 20 minutes after the loss of the FPC may prevent postoperative paraplegia nearly completely.