脊髓损伤大鼠运动及神经功能自然恢复规律的探讨

Natural recovery of locomotor and neurological function in rats after spinal cord injury

目的观察不完全脊髓损伤（SCI）大鼠运动及神经功能自然恢复情况，为SCI后运动训练时机选择提供依据。方法共选取45只成年SD大鼠，分为实验组（40只）和假手术组（5只）。实验组手术切除T10椎板暴露脊髓，采用改良Allen＇s撞击法致SCI；假手术组仅手术切除T10椎板暴露脊髓。实验组分别于损伤前及损伤后1，3，5．7，14d，21d和28d，假手术组分别于术前及术后1，3，5，7d时采用斜板试验、改良Tarlov评分、Basso-Beattie-Bresnahan（BBB）评分进行运动功能评定，采用脊髓诱发电位评定神经功能。实验组于上述各时间点分别取5只大鼠处死，假手术组于术后7d时处死，取2组大鼠T10节段脊髓进行形态学检测。结果①实验组大鼠在损伤后1～3d斜板角度、改良Tarlov评分和BBB评分均较损伤前显著降低，自损伤后5d时开始增加，至14d时达到平台期，显著高于术后1，3，5d及7d时水平（P〈0.05），与21，28d时结果比较，差异无统计学意义（P〉0.05），但仍低于损伤前水平（P〈0．05）。假手术组术后与术前比较，差异均无统计学意义（P〉0．05）。②实验组大鼠在损伤后1d时脊髓体感诱发电位（SCEP）潜伏期较损伤前明显延长（P〈0．05）；随时间进展该潜伏期呈逐渐缩短趋势，至术后21d时达到平台期，但仍显著长于损伤前水平（P〉0．05）；波幅在损伤后1d时明显降低，随时间进展呈逐渐增加趋势；假手术组术后各时间点潜伏期和波幅与术前比较，差异均无统计学意义（P〉0.05）。③2组大鼠术前脊髓结构完整，实验组术后1～3d脊髓灰白质可见片状出血、细胞肿胀及变性；术后5～7d炎性细胞减少，可见细胞内嗜碱性颗粒沉积、胶质细胞及少量神经纤维增生等；术后14～28d可见胶质细胞、神经纤维增生明显，细胞内有空泡结构形成；假手术组大鼠脊髓形态学方面手术前后无明显改变。结论SCI大鼠运动功能、神经功能及脊髓病理形态学变化均与损伤时程密切相关，其运动功能改善一般于损伤后14d时达到平台期，而神经功能改善一般于损伤后21d时达到平台期。

Objective To observe the natural recovery of locomotor and neurological functioning in rats after incomplete spinal cord injury. Methods Forty-five Sprague-Dawley rats were divided into two groups： an experimental group and a sham-operation group. In the experimental group, the spinal cord was exposed at the T10 level by laminectomy, and an animal model of spinal cord injury （SCI） was created using a modification of Allen＇s method. The sham-operation group received only laminectomy without spinal cord injury. Locomotor and neurological functioning were evaluated using inclined plane tests, modified Tarlov scores, Basso-Beattie-Bresnahan （BBB） scales and spinal cord evoked potential （SCEP） before the operation and on the 1st, 3rd, 5th, 7th, 14th, 21st and 28th day post surgery. Histomorphological changes were observed by light microscopy. Results （ 1 ） In the experimental group, the angles of the inclined plane test and the Tarlov and BBB scores had decreased significantly 1 and 3 days post-injury compared with those before the injury, and then increased gradually from the 5th day onwards, and peaking at the 14th day after injury. In the sham-operation group no significant changes in the inclined plane test results, modified Tarlov scores or BBB scores were observed 1 , 3, 5 or 7 days post surgery. （2） In experimental group, SCEP latency had increased significantly on the 1st day after SCI, but it then decreased gradually until reaching a plateau at the 21st day after the operation. The SCEP amplitude also decreased significantly at the 1st day after SCI,then increased gradually from the 3rd to the 21st day. In the sham-operation group, no significant changes in SCEP latency or amplitude were observed. （3） One and 3 days after the operation, hemorrhage and edema in the spinal cord as well as nerve fiber degeneration was observed in the experimental group. From day 5 to day 7, empty cavities formed gradually and astrocytes increased, a few nerve fibers grew. By days 14 and 28, more nerve fibers and astrocytes were found. Conclusion The recovery of locomotor and neurologic function correlated closely with the natural course of spinal cord recovery, and becomes stable 14 to 21 days after injury.