建立人工膀胱反射弧治疗脊髓损伤后弛缓性膀胱的实验研究

目的探讨利用脊髓损伤平面以上健存的体反射重建人工膀胱反射弧,恢复脊髓损伤(spinalcordinjury,SCI)后膀胱排尿功能。方法1岁龄雄性Beegle犬8只,体重9.5±2.0kg。取后正中切口暴露L4～S3的棘突和椎板,全椎板切除后暴露硬膜和脊神经根,在硬膜外初步分离和确认L6和S2前根。确定犬左侧为实验侧,将左侧L6与S2前根分别在穿神经根管处切断,切开硬膜囊,从硬膜外L6和S2前根追溯硬膜内神经根,在显微镜下将L6和S2前根在硬膜内吻合。经一段时间轴突再生后,建立“膝腱-脊髓中枢-膀胱”人工反射弧。神经缝合术后8个月,在破坏S1～S4脊髓节段前后,分别进行神经电生理、膀胱肌电图及尿流动力学等远期功能观察。结果术后8个月,3只犬死亡,3只犬未能分离出吻合的神经,无实验结果。余2只犬均获得满意结果,定为1号和2号犬,进行观察。刺激(连续刺激强度200μV,刺激间隔为5ms)截瘫前和截瘫后2只犬左侧L6后根、神经吻合口,均可在吻合口远端记录到运动诱发电位,其波形和波幅相似;尿流动力学检查可见,当刺激开始时膀胱内压迅速上升,而腹内压增加幅度较小,刺激中止后膀胱内压迅速下降,证实膀胱内压升高主要是由逼尿肌收缩产生,电刺激左侧L6后根和吻合口膀胱内压升高值均可达到正常的60%左右。结论利用脊髓损伤平面以上健存的体反射重建膀胱反射通路是成功和有效的,体神经的运动支通过轴突再生能够长入自主神经的副交感神经纤维,并具有良好的传导运动兴奋的功能。

EXPERIMENTAL STUDY ON THE ARTIFICIAL BLADDER REFLEX ARC ESTABLISHED IN THERAPY OF FLACCID BLADDER AFTER SPINAL CORED INJURY

OBJECTIVE: To establish the artificial bladder reflex arc by the normal body reflex pathway above the horizon of spinal cord injury to reinnervate the flaccid bladder and restore bladder micturition function. METHODS: An intradural microanastomosis was performed on the L6 ventral root to the S2 ventral root. After axonal regeneration,the "patellar ligament-spinal cord center-bladder" reflex pathway was reestablished. A long-term function of the reflex arc was observed in the nerve electrophysiological experiment, detrusor electromyography experiment, and urodynamic testing 8 months after anastomosis. RESULTS: Trains of the stimuli (200 microV, 5 ms) in the left L6 dorsal root and the nerve at the anastomosized site resulted in motor evoked potential from the disal to the anastomosized site before and after the spinal cord was destroyed horizontally between S1 and S4 segment levels in 2 Beegle dogs. The figure and amplitude of the evoked potential were similar to those of the control and general stability which showed a noninterventional wave. The urodynamic test revealed a rapid increase of the bladder pressure and a minor increase in the abdominal pressure. This showed that the bladder detrusor mainly resulted in the pressure increase. The bladder pressure increased to 60% of the normal on average compared with the controls when resulted in the left L6 dorsal root and the nerve anastomosized site were stinulated. CONCLUSION: The long-term observation by the nerve electrophysiological experiment, detrusor electromyography experiment, and urodynamic test indicate that the new artificial reflex arc can be established successfully. The somatic motor axons can regenerate into the parasympathetic endoneurial tubes of the autonomic nerve.