正中神经损伤修复后大脑运动皮层可塑性变化的实验研究

目的 研究正中神经损伤修复后运动皮层可塑性的变化过程.方法 SD大鼠35只,分为对照组和手术组,手术组又分为术后1 d和1周、4周、8周、12周、16周,每组5只,左侧肢体为损伤修复侧,将正中神经在内侧束分支以远2.0 cm处切断后缝合.通过皮层内微电极刺激技术,定量评价正中神经损伤恢复过程中运动皮层的可塑性变化.结果 正中神经屈指屈腕区运动皮层面积[(0.85±0.1)mm2,-x±s,下同].术后1 d、1周,对侧皮层正中神经屈指屈腕区被桡神经、肌皮神经、腋神经位点占据,没有无反应位点出现;术后4周、8周和16周,运动皮层出现无反应位点;术后8周、12周,对侧皮层出现屈指屈腕位点,差异有统计学意义(P＜0.05);术后16周,与健康组相比,差异无统计学意义(P＞0.05),运动皮层内没有无反应位点出现.结论 成年大鼠正中神经损伤后其对侧运动皮层发生可塑性改变,是一个动态的过程,但其机制还需进一步的研究.

Experimental study on changes of the motor cortex plasticity following median nerve injury and repair

Objective To investigate changes of plasticity of the motor cortex at different intervals following median nerve injury and repair.Methods Thirty-five adult Sprague Dawley rats were randomly divided into 7 groups：normal group and 1 day，1，4，8，12，16 weeks group after median nerve repair，with 5 each.The median nerve of the left side was transected 2 cm distal to the medial cord and sutured immediately.Intracortical microstimulation technique was used to quantitatively evaluate the changes of plasticity of the corresponding left forelimb motor region. Results The area of finger and wrist flexion zone at the motor cortex was[(0.85±0.1)mm2，-x±s，下同].The zone of finger and wrist flexion was occupied by the sites of the radial nerve.musculocutaneous nerve and axillary nerve 1 day and l week postoperatively.There were no unresponsive sites.Unresponsive sites appeared at 4，8 and 16 weeks postoperatively in the motor cortex.The sites of finger and wrist flexion presented in the contralateral hemispheres 8 and 12 weeks postoperatively，and there was signifieant difference in area when compared to the normal group(P＜0.05).Sixteen weeks postoperatively there Was no significant difference compared to the normal group(P＞0.05).Condusion The motor cortex of the adult rat has plasticity following median nerve injury and repair.It is a dynamical procedure.Its meehanism need to be further studied.