| Objective:Use the posterior vertebral column resection(PVCR) to establish animal models of spinal shortening with the beagle dogs.Use the EMG detector and laser doppler flowmetry to observe the somatosensory evoked potential (SEP) and spinal cord blood flow change after segmental vessels ligatied and the spinal shortening to investigate the security numbers of ligated segmental vessels and the influence of the spinal cord conduction fuction after spinal shortening, in order to provide the reference about PVCR on surgery.Methods:The beagle dogs, which are provided by the Animal Department of Kunming Medical University,were used as test animals.Thirty beagle dogs (mean weight:10.36kg, numbered 1-30) were randomly divided into A, B, C, D, E five groups, with six beagles in each group.At the first step of the experiment, each beagle dog was ligated zero, two, three, four and two multiply four pairs segment vessels.which was L3 centric.in Group A(control group), B, C, D and E, respectivly. After induction of anesthesia, monitoring detectors of the SEP were connected to the experimental animal limbs, and posterior approach was used to exposure and resect vertebral posterior structure of L1-L5. Spinal cord exposure were attached in L3. The laser doppler flowmetry was used to measure spinal cord blood flow, according to the planing groups. At the same position, the measurment was repeated 3 times. At the second step of the experiment, PVCR was approched to resect the L3 vertebral, in group A and C. These experimental dogs in Group A and C were randomly divided into three sub-groups, in which there were two dogs, due to no spinal shortening, one third shortening or two third shortening. The value of SEP and PU change was detected at 5 and 30 minutes in each subgroup.Results:(1) There were no statistical significance differences among group A、B、C、 D、E about the body weight, body length, body temperature of the experimental animal (P> 0.05), also no statistical significance difference of RBC, Hb, PT, APTT before operation (P> 0.05);(2) There were no statistical significant differences of PU in five groups while lamina resection(P> 0.05), also no differences between ligate two multiply four of segmental vessels and ligate zero (P> 0.05), The PU value of ligated three pairs were significantly lower than ligated zero or two pairs (P< 0.01), while it is lower than two multiply four vessels (P< 0.05). The PU of ligate four pairs of vessels were significantly lower than ligate zero or two pairs (P< 0.01), and three pairs(P< 0.05); There were no statistical significant differences between ligate two pairs or two multiply four segments and lamina resection(P> 0.05), the PU value of ligate three or four pairs of segments were decreased than lamina resection (P< 0.01). In group A and C, the PU, after shortening a third, were higher than no shortening (P< 0.05), shortening two-thirds than no shortening was reduced too (P< 0.01), the PU was increased when shortening a third than ligate segments vessels (P> 0.05), but decreased when shortening two third (P< 0.05). There was no difference of PU value between shortening one third and five minutes later(P> 0.05), but further increased in thirty minutes (P< 0.05). and than it further reduced in 30 minutes (P< 0.05); The value of PU was decreased after five minutes of shortening two third (P> 0.05), and it further decreased in thirty minutes (P< 0.05).(3) There were no statistical significance among the five groups of SEP (LAT and AMP); There were no statistical significant differences among ligate two pairs or two multiply four and ligate zero vessel of SEP (P> 0.05); The sincubation period extend and amplitude significantly decreased while ligate three pairs of segmental vessels than ligate zero (P< 0.01). the incubation period extend the amplitude decreased than ligated two pairs and two multiply four (P< 0.05), when it ligated four pairs, the SEP’ sincubation period extend and amplitude decreased significantly than ligate two pairs and two multiply four. (P< 0.01). but it decreased than ligated three pairs. There were no differences of SEP between shortening a third and no shortening in group A. in preoperative (P< 0.05),but the incubation period extend 6.3%and amplitude decreased 50.3%was happened when shortening two-third (P< 0.01); The incubation period extend and amplitude increased both after five and thirty minutes (P< 0.05)in group A. In group C the latency were extend and amplitude were decreased than preoperative when no spinal shortening(P< 0.05), while shortening a third than preoperative (P> 0.05) and shortening two third (P< 0.01); There was a latency advance and amplitude increased after five minutes (P< 0.05) when spinal shortening one third and it was continued in thirty minutes (P< 0.05). The latency were extend and amplitude were decreased than no spinal shortening and it was still decreased in five (P< 0.05) and thirty minutes(P< 0.05).Conclusion:1. Ligated three or more segment vessels will significantly reduce the spinal cord blood flow, at the same time, damage the spinal cord conduction function.2.One third spinal shortening (the 1/3 height of a whole vertebral and two intervertebral discs near by) may help to increase the spinal cord blood flow and improve the spinal cord conduction function3.Two third spinal shortening (the 2/3 height of a whole vertebral and two intervertebral discs near by)) will significantly make the spinal cord blood flow decreased, at the same time, damage the spinal cord conduction function... |
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