经皮硬膜外置管法建立绵羊急性颈脊髓损伤模型

目的应用经皮穿刺技术向硬膜外置入可扩张球囊导管,建立绵羊急性颈脊髓压迫性损伤模型。方法成年雄性绵羊12只,随机分为对照组(A组)、0.6mL压迫组(B组)和1mL压迫组(C组),每组4只。所有动物均使用经皮穿刺鞘管,透视下自腰骶椎板间隙将3Fr球囊导管置入硬膜外,并输送至C6/7水平。1周后B、C组动物分别以0.6和1mL容量扩张导管球囊,持续压迫颈髓1h后撤除;A组动物不作处理。各组动物均在穿刺操作及球囊扩张前后接受CT和MRI检查,计算球囊导管的椎管侵占率,并采用改良Tarlov评分评估神经功能。分别于球囊扩张后24h及48h处死每组各2只动物,取压迫节段颈髓送病理检查。结果所有动物均顺利置管。CT检查测得置管后A、B、C组椎管侵占率(%)依次为9.1±0.2、9.1±0.2和8.9±0.2。扩张球囊后B、C组椎管侵占率(%)分别增加到45.5±2.5和78.3±2.3。MRI检查提示扩张的球囊对颈髓腹侧形成压迫。置管后各组动物神经功能正常,扩张球囊后B、C组出现后肢运动减退,且与扩张容量相关。病理结果提示B、C组在球囊扩张24h后,C6/7水平脊髓灰质前角神经元数量减少,胞体缩小,白质轻度脱髓鞘,部分轴突空泡样变;压迫48h后,病理改变进一步加重。结论经皮置管技术避免了对脊髓周围正常组织的破坏,是一种能够模拟临床实际致伤机制的急性颈脊髓损伤造模方法。

Percutaneous epidural balloon catheter insertion for establishing a sheep model of acute cervical spinal cord injury

Objective To develop a percutaneous technique with expandable balloon catheter for establishing a sheep model of acute cervical spinal cord compression injury. Methods Twelve adult male sheep were randomized into 3 groups: control (A, n=4), 0.6 mL compression (B, n=4) and 1 mL compression (C, n=4) groups. All animals received epidural balloon catheter (3Fr) insertion using a percutaneous trans-lumbosacral interlaminar space technique similar to the method used in vascular access for angiography. The balloon catheter was advanced under fluoroscopic guidance until its distal tip reached the C_6/7 level. One week later, the balloons of group B and C were inflated by 0.6 mL and 1 mL half-strength contrast material; the balloons were left inflated for 1-hour and then deflated. Animals in group A received no treatment. CT and MR images were taken before and after surgical procedures. Quantitative assessment of spine canal occupying rate was accomplished by using a software program based on CT results. Motor functions of animals were assessed by modified Tarlov scale. Two animals were sacrificed each time at 24 h and 48 h after inflation in each group. Spinal segments of the injured level were then obtained for pathologic examination. Results Balloon catheters were successfully inserted in all animals, and the spinal-canal-occupying rates were (9.1 ±0.2)% in group A, (9.1±0.2)% in group B, and (8.9±0.2)% in group C after insertion. After inflation, the rates increased to (45.5±2.5)% in group B and (78.3±2.3)% in group C, and MRI findings indicated ventral compression of the cervical spinal cord. Hind limb movement remained normal after catheter insertion in all groups. Animals in group B and C became paraplegic after inflation, and a positive correlation between injection volume and Tarlov score was observed. Pathological results demonstrated neuron atrophy, increased gap around the neurons, mild demyelinated and vacuolar degeneration in both group B and C at C_6/7 level 24 h after injury. Pathological changes deteriorated at 48 h after injury. Conclusion Percutaneous epidural balloon catheter insertion can avoid surgical exposure of normal tissues around the spinal cord, and it may serve as a method for establishing acute cervical spinal cord injury model simulating the clinical condition.