水下冲击波致兔脊髓损伤的神经机能变化及其病理特点

Neuro-electrophysiological changes and pathological features of spinal cord injury caused by underwater shock waves in rabbits

目的探讨水下冲击波致兔脊髓损伤的神经机能变化及其病理特点。方法选取48只新西兰大白兔随机分为A、B、C、D组各12只,通过手术将大白兔脊髓暴露后将其固定于封水仓内,仅椎板切除段脊髓外露于冲击波作用之下,用铵松蜡炸药2 g为水下爆源,其中A、B、C组分别按冲击波到达脊髓表面的超压峰值2.6 MPa、2.8 MPa、3.0 MPa致伤,检测冲击波的超压峰值及作用时间。D组不致伤,作为对照组。通过BBB法运动学评分、体感诱发电位检测、脊髓组织苏木精-伊红(HE)染色及透射电镜观察,评估各组水下冲击波致脊髓损伤后的神经机能变化及病理特点。结果水下冲击波致伤后,实验组动物均瘫痪,D组没有瘫痪。致伤12 h及24 h后A组、B组、C组的BBB评分依次减低(P<0.05),且均低于D组(P<0.05);致伤24 h后A、B、C各组大白兔BBB评分低于致伤12 h后(P<0.05)。致伤12 h及24 h后A组、B组、C组的体感诱发电位潜伏期依次延长(P<0.05),且均高于D组(P<0.05);波幅依次下降(P<0.05),且均低于D组(P<0.05)。与致伤12 h后比较,A组、B组、C组致伤24 h后的潜伏期均延长(P<0.05),A组及B组波幅均下降(P<0.05)。致伤48 h时组织形态学和电镜下示A组、B组、C组脊髓出血坏死,结构破坏,髓鞘板层分层,轴索变形水肿,A组、B组、C组动物脊髓HE染色阳性率依次降低(P<0.05),且均低于D组(P<0.05)。结论水下冲击波可造成水下动物脊髓损伤,其致伤程度与动物接受的爆炸冲量有关,且在一定时间内存在继发性损伤。

Objective To explore the neuro-electrophysiological changes and pathological features of spinal cord injury caused by underwater shock waves in rabbits. Methods Forty-eight New Zealand rabbits were randomly divided into Group A, Group B, Group C and Group D, with 12 rabbits in each group. After surgical exposure of spinal cord, the rabbits were fixed in the sealing water storehouse, and only the spinal cords with laminectomy were exposed to shock waves. Ammonium nitraterosin paraffin explosive with the dose of 2 g was taken as underwater blasting source. The rabbits of Group A,Group B and Group C were vulnerated by the overpressure peaks of 2.6 MPa,2.8 MPa, 3.0 MPa from shock waves to spinal cord surfaces, respectively. The overpressure peak and actuation duration were measured. Group D was not vulnerated and was taken as control. The neuro-eleetruphysiological changes and pathological features of spinal cord injury in each group were evaluated using BBB Kinematics score, somatosensory evoked potential, hematoxylin-eosin （HE） staining of spinal cord tissues and transmission electron microscopy after spinal cord injury caused by underwater shock waves. Results After 12 hotrrs of injury caused by underwater shock waves, paralysis was observed in all rabbits in the experimental groups, but not in Group D. After 12 and 24 hours of injury, the BBB scores decreased in the order of Group A, Group B and Group C （ P 〈 0.05 ）, and the scores of these three groups were lower than the score of Group D（P 〈0.05）. The BBB score after 24 hours of injury was lower than that after 12 hours of injury in Group A, Group B or Group C （ P 〈 0.05 ）. After 12 and 24 hours of injury, the latent period of somatosensory evoked potential prolonged in the order of Group A, Group B and Group C （ P 〈 0.05 ）, and the potential of these three groups were higher than that of Group D （ P 〈 0.05 ）. And the amplitude of somatosensory evoked potential decreased in the order of Group A, Group B and Group C （ P 〈 0.05 ）, and the amplitude of these three groups were lower than that of Group D（ P 〈 0.05 ）. The latent period was longer in Group A, Group B or Group C, and the amplitude decreased after 24 hours of injury in Group A or Group B compare to those after 12 hours of injury （ P 〈 0.05 ）. After 48 hours of injury, the results ot histomorphology and electron microscopy showed that hemorrhage and necrosis structure damage,myelin layered plate layer,axonal deformation edema were observed in the spinal cords of Group A,Group B and Group C. The positive rate of HE staining of spinal cord tissues decreased iv the order of Group A, Group B and Group C （ P 〈 0. 05 ）, and the rates of these three groups were lower than that of Group D （P 〈 0. 05 ）. Conclusion Underwater shock wave can cause underwater spinal cord injury in animals, and the severity of injury is associated with the explosion impulse accepted,and the secondary injury exists during a certain period.