| Objective: 1. Established Beagles approach by L3 vertebral height the whole spinal surgery posterior vertebral column resection (PVCR) model to monitor different intervention stage somatosensory evoked potential (SEP) change. To analyze the effect of function of spinal conduction on ligation segmental vessels variable in number, dura mater spinalis superficial rete vasculosum occlusion, spinal cord circumferential decompression, shortening different spinal cord distance and so on.2. Myeloid tissue pathological changes observation in different experimental stages by light and electron microscopic. The relationship of spinal conduction function change and the spinal nerve cyto-architectonics change.Methods: 42 beagle dogs random divided into A, B, C, D, E, F, G seven groups. Each group divided into (A1?B1?C1?D1?E1?F1?G1) (shortening one-thirds) and(A2?B2?C2?D2?E2?F2?G2)(shortening two-thirds) two subgroups by shortening distance, 3 beagle dogs in each group. Spinal conduction function by limbs SEP monitoring. Each experimental stage at least 30 minutes. The spinal injury alarm actuation value was defined as the decline of wave amplitude over 10% and/or the elongation of latent period over 50%. In the process of Beagles approach by L3 vertebral height the whole spinal surgery posterior vertebral column resection(PVCR)model establishment, implement intervene on the experimental animals groups with the following conditions: spinal segment vascular ligation( group A :0 × 0, group B: 1 X 1,group C: 2 X 2, group D:3 X 3, group E: 2 X 4, group F:4 X 4, group G: 5 X 5),endorachis superficial rete vasculosum occlusion, spinal cord circumferential decompression and spinal cord distance shortening. After the intervention condition was completed, incision lumbar 3 spinal cord, spinal cord slices to observe the myeloid tissue pathological change. Compare with the beagle dogs limbs SEP amplitude, latent period data on different experimental group and different intervention stage to analyze the spinal conduction function change of each subgroup on each intervening stages, and the spinal nerve cyto-architectonics change as the spinal conduction function change.Results: (1) Ligation of segmental vessels: preoperative both lower extremities(BLE)comparation of seven groups, SEP latent period and wave amplitude change between seven groups was no significant difference(P > 0.05). Compare with preoperative,prolonged latency and decreased amplitude has been showed after group B and group C ligated one and two pair segmental vessels. It is not up to the spinal injury alarm actuation value and no significant difference(P > 0.05), compare with group B and group C, prolonged latency and decreased amplitude of group D has been significantly changed,it is not up to the spinal injury alarm actuation value. It was significant difference(P < 0.05); The latent period and wave amplitude of group E,group F and group G has been significantly changed and up to the spinal injury alarm actuation value. Compare with the preoperative latent period and wave amplitude, the group E, group F and group G was significant difference(P<0.05).(2) Endorachis superficial rete vasculosum occlusion: Compare with the preoperative,prolonged latency and decreased amplitude of group A. It was no significant difference(P>0.05); After dura mater spinalis superficial rete vasculosum occlusion,the SEP latent period and wave amplitude of group B, group C and group D has been changed,it was significant difference(P< 0.05), but it's not up to the spinal injury alarm actuation value. After dura mater spinalis superficial rete vasculosum occlusion,the SEP latent period and wave amplitude of group E, group F and group G has been further changed. It was significant difference(P<0.05); compare with the SEP latent period and wave amplitude of each group after segmental vessels ligation, it was significant difference(P < 0.05). It shows that the latent period and wave amplitude has effect on spinal cord function when ligate ? 3 segmental vessels and occlude endorachis superficial rete vasculosu, but it doesn't lead to the spinal cord disturbance.(3) Spinal cord circumferential decompression: compare with the SEP latent period and wave amplitude of seven groups was recovered after endorachis superficial rete vasculosum occlusion. The latent period has been moved up and wave amplitude has been increased. Compare with the SEP latent period and wave amplitude of four groups(group A, group B, group C and group D) after endorachis superficial rete vasculosum occlusion, the latent period and wave amplitude was significant difference(P<0.05), compare the subtotal vertebrectomy of the cervical spine with preoperative, the latent period and wave amplitude of three groups(group A, group B and group C) was no significant difference(P > 0.05), the SEP was normalized.Compare with group D, the wave amplitude relatively has been decreased, it was significant difference(P < 0.05), but the latent period change was no significant difference(P > 0.05). After the vertebroplasty excision, the circumferential decompression has protective effects on spinal conduction function to recover the lesions of spinal cord when ligate ? 3 segmental vessels. The SEP latent period and wave amplitude of three groups(group E, group F and group G) with varying degrees recovery after endorachis superficial rete vasculosum occlusion, it was significant difference(P< 0.05). But it was not recovery to the below of spinal cord lesions value,it shows that the spinal cord has been injured.(4) Shortening clearance of spine 1/3 : after seven groups(group A1?group B1?group C1?group D1?group E1?group F1?group G1) shortening clearance of spine 1/3,compare with circumferential decompression, the SEP latent period was advanced, the wave amplitude has been leveled up. It was significant difference(P<0.05); The SEP signal of four groups (group A1,group B1,group C1 and group D1) has been restore to the level of preoperative. The SEP signal of four groups (group E, group F and group G) has been recover,but it still restore to under the level of spinal cord lesions value. It shows that shortening 1/3 has meaning for spinal nerve conduction function.(5) Shortening clearance of spine 2/3: after seven groups(group A2?group B2?group C2?ggroup D2?group E2?group F2?group G2) shortening clearance of spine 2/3,compare with circumferential decompression, the SEP latent period was delayed, the wave amplitude has been decreased. Both up to the spinal injury alarm actuation value,it was significant difference(P < 0.05); after shortening clearance of spine 2/3(group E2?group F2 and group G2) and the SEP circumferential decompression, the wave amplitude was decreased and latent period was prolonged. It was significant difference(P<0.05), it was up to spinal injury alarm actuation value.(6) Isolate spinal cord of seven groups (group A, group B, group C, group D, group E,group F and group G). Observe the spinal cord nerve cells histopathological chang by light microscope and transmission electron microscope (TEM). It can be observed the spinal cord central canal hemorrhagic necrosis, the central canal was ruptured and deformation. The mitochondria obviously swollen, the number of rough surfaced endoplasmic reticulum (RER) obviously decreased, the chromatin margination was integrated and apoptosis and cell death by the transmission electron microscope (TEM) observation. The spinal cord central large hemorrhagic and necrosis, certain tissues was liquefied by light microscope observation. The apoptosis and necrotic lesion was significantly increased by observation TEM.Conclusions: 1. As the ligation of segmental vessels numbers increased,the spinal cord conduction became poorer when established 3 vertebral height the whole spinal surgery posterior vertebral column resection(PVCR) model and ligation of ?3 segmental vessels. But the SEP was not show the alarm value, the spinal nerve conduction function normal. It shows the alarm value when the ligation of ? 4 segmental vessels, it leads to the spinal cord conduction dysfunction to spinal injury.2. Endorachis superficial rete vasculosu occlusion has effect on the spinal cord conduction, it further effect on the spinal cord conduction by endorachis superficial rete vasculosu occlusion in the segmental of ?4 vascular model.3. After v3 vertebral height the whole spinal surgery posterior vertebral column resection (PVCR) and circumferential decompression, the spinal cord conduction has been improved. It has the protective function on the spinal cord conduction.4. The clearance shortening spinal after vertebral column resection. The spinal cord conduction has been improved when shortening the shortening ?1/3 clearance; it lead to the spinal cord conduction dysfunction to spinal injury when shortening the shortening ?2/3 clearance.5. There is obvious relativity between relativity spinal nerve conduction function and pathological changes of spinal cord. It's sensitive for SPE to spinal injury,the SEP wave amplitude was decreased, the latent period was prolonged and the spinal cord neurons injured. The SEP objective reflect the conduction function of spinal cord. |
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