臂丛神经根性撕脱伤后神经根回植的实验研究

目的探讨臂丛神经根性撕脱伤后，神经根回植脊髓对前角运动神经元的挽救效应及作用机制，观察回植后神经根的生长情况。方法成年Wistar大鼠30只，随机分两组，每组15只。取两组大鼠左侧为正常对照侧，不作任何处理；右侧进行模型制备。进行C4-6右侧椎板减压，于椎管内硬膜外撕脱C5、6神经根。实验组将C5神经前根回植入脊髓前角，用11—0无创缝线缝合2针，后根旷置，C5神经根埋入周围肌肉；对照组将撕脱的C5、6神经根埋入肌肉。术后2、4、6、8及12周取材，C6脊髓HE染色，观察脊髓前角运动神经元的形态和数量的变化；C6神经根作硝酸银染色，观察神经纤维的再生情况。结果两组大鼠术后均表现为右上肢上干瘫痪，余肢体活动正常。对照组撕脱的神经根与周围肌肉粘连；实验组神经根植入脊髓处有较多瘢痕组织粘连，未见神经根从脊髓上脱落。各时间点HE染色显示，实验组运动神经元胞体萎缩，部分运动神经元水肿，尼氏体减少或消失；对照组神经细胞胞体缩小。术后各时间点对照组脊髓前角运动神经元成活率分别为60．9％±5．8％、42．3％±3．5％、30．6％±6．1％、27．5％±7．9％及20．4％±6．8％，实验组为67．1％±7．4％、56．3％土4．6％、48．7％±8．8％、44．2％±5．5％及42．5％±8，3％，差异有统计学意义（P〈0．01）。硝酸银染色显示，实验组C6神经根硝酸银染色显示前角运动神经元能通过轴突再生进入回植的神经根内；对照组显示为神经纤维的退变，有髓神经纤维数目减少。结论臂丛神经根性撕脱伤后前根回植脊髓后，能够明显减少前角运动神经元的变性死亡。神经根回植后，运动神经元能通过轴突再生进入回植的神经根内，并有新生的有髓神经纤维生长。

EXPERIMENTAL STUDY ON REIMPLANTATION OF VENTRAL ROOT INTO SPINAL CORD AFTER BRACHIAL PLEXUS AVULSION

OBJECTIVE: To investigate the survival effect and reaction mechanisms of motor neurons after reimplantation of the avulsed root into the spinal cord, and to observe the survival and differentiation in the spinal cord after brachial plexus roots avulsion. METHODS: Thirty adult Wistar rats were randomly devided into the control group and the experimental group (n = 15). Laminectomy of C4-6 was performed via a posterior approach. The ventral and dorsal roots of C5,6 were both avulsed from the spinal cord outside the dura mater and within the vertebral canal. For the experimental group, the ventral root of C6 was reimplanted into the ventral horn under microscope. The dorsal root was left. The ventral and dorsal roots of C5 were placed inside the nearby muscles. For the control group, the ventral and dorsal roots of both C5 and C6 were placed inside the nearby muscles. At 2, 4, 6, 8, 12 weeks postoperatively, the C6 spinal cord was stained with HE. The changes of the number and morphology of motor neurons were observed on HE-stained sections. The C6 spinal nerve root was stained with silver nitrate, and the regeneration of nerve fiber was observed. RESULTS: All rats were recovered well and their wounds were healed at primary stage. The gross observation showed that the avulsed nerve roots in control group adhered to adjacent muscles, however the one in experimental groups which had been implanted into spinal cord adhered to scar tissues and were not separated from spinal cord. At each time point postoperatively, the HE-stained transverse sections showed that the number of motor neurons decreased significantly with soma swollen and atrophied, Nissle bodies decreased or disappeared. The survival rates of motor neurons in the control group were 60.9% +/- 5.8%, 42.3% +/- 3.5%, 30.6% +/- 6.1%, 27.5% +/- 7.9% and 20.4% +/- 6.8% respectively; in the experimental group, the survival rates were 67.1% +/- 7.4%, 56.35% +/- 4.6%, 48.7% +/- 8.8%, 44.2% +/- 5.5% and 42.5% +/- 8.3% respectively. The survival rates of motor neurons in the experimental group was higher than those in the control group at all time points, showing statistically significant difference (P < 0.01). At 12 weeks postoperatively, the silver nitrate stained specimen from the C6 nerve root showed regeneration of the motor neurons in the ventral horn into the reimplanted nerve root through axon in the experimental group, but the degeneration of the nerve fiber appeared and the number of the myelinated nerve fiber decreased in the control group. CONCLUSION: Through reimplantation of the avulsed ventral nerve root into the ventral horn, degeneration of the motor neurons in the ventral horn can be reduced. After reimplantation of avulsed nerve root, there is axonal regrowth of motor neurons into the spinal nerve root and regeneration of the myelinated nerve fiber also appears.