脊髓挫伤速度对颈脊髓原发性损伤影响的实验研究

目的　确定脊髓挫伤速度是脊髓损伤的因素，探讨不同速度的脊髓挫伤对大鼠颈脊髓原发性损伤的影响。  方法    20只成年雄性Sprague-Dawley大鼠随机分为快速组（500 mm/s，n=8）、慢速组（5 mm/s,n=8）和对照组（n=4）。用直径为4 mm的平头圆锥打击头在C5水平产生1.5 mm的挫伤位移。损伤后即行心脏固定，切取以挫伤部位为中心长约1.5 cm的脊髓组织。行连续矢状位冰冻切片。HE染色观察脊髓大体形态，计算出血量。β-APP免疫组化后观察轴索损伤程度。  结果　挫伤后观察到脊髓表面有一带状出血，且快速组出血带颜色更深。快速组挫伤位移为(1.50±0.05) mm，最大力为(5.3±1.2) N；慢速组挫伤位移为(1.51±0.04) mm，最大力为(2.8±0.6) N，两组间最大力的差异有显著性（P=0.001）。HE染色显示脊髓出血大部分都集中在灰质，白质相对较少。快速组脊髓总出血量、灰质出血量和白质出血量分别为0.94、0.71和0.23 mm3，慢速组分别为0.55、0.43和0.12 mm3，其中两组间总出血量和灰质出血量的差异有显著性（P＜0.05）。β-APP免疫组化观察到快速组轴索断裂比慢速组更为严重。  结论　脊髓挫伤速度是影响脊髓原发性损伤的因素，快速的脊髓挫伤导致的原发性脊髓损伤更为严重，导致更多的脊髓出血和轴索断裂。

Effects of contusion velocity on the cervical primary spinal cord injury in rats

Objective　To verify the contusion velocity as a factor of spinal cord injury and determine cervical primary spinal cord injury in rats at different contusion speed.　Methods　Twenty adult and male Sprague-Dawley rats were divided randomly into the fast group (500 mm/s, n=8), the slow group (5 mm/s, n=8) and the sham control group (n=4). The contusion tip was a cone-shape flat head with a diameter of 4 mm, and driven by a servo-electromagnetic material testing machine to perform a 1.5 mm contusion at the dorsal cord of C5. All rats were perfused intracardially right after injury. The spinal cord sample with 15 mm in length and the epicenter in the middle was sectioned for histological test. Serial parasagittal sections of the spinal cord were cut and then stained with Hematoxylin and Eosin for inspection of the gross morphology and quantification of hemorrhage volume. The axonal injury was detected with β-amyloid precursor protein by immunohistochemistry.　Results　Hemorrhage was observed on all spinal cords after contusion. The hemorrhage looked darker in the fast group. The contusion displacement for the fast and slow contusion groups was (1.50±0.05) mm and (1.51±0.04) mm, and the maximal force (5.3±1.2) N and (2.8±0.6) N, respectively.  There was significant difference in the maximal force between the groups (P=0.001). The hemorrhage was mainly located in the gray matter and few in the white matter. Total hemorrhage, the hemorrhage in the gray and white matter were 0.94 mm3, 0.71 mm3 and 0.23 mm3 for the fast group, and 0.55 mm3, 0.43 mm3  and 0.12 mm3 in the slow group, respectively. There was significant difference in total hemorrhage and hemorrhage in the gray matter between two contusion groups (P＜0.05). Axonal disruption seemed more serious after contusion at higher speed. 　Conclusion　The present study suggested that the contusion velocity is a factor of primary spinal cord injury. Contusion at higher speed results in severer primary spinal cord injury, more hemorrhage and axonal disruption.