大鼠脊髓损伤后膀胱生理反射弧重建的实验研究

目的 探讨利用截瘫平面以上健存的神经根,与硬脊膜内骶神经前后根分别吻合,建立人工膀胱反射通路,重建膀胱生理反射弧的有效性.方法 取3月龄雄性SD大鼠20只,体重250～300 g;右侧为实验侧,左侧为对照侧.将大鼠右侧L5前根近端与右侧S2前根远端,L5后根近端与S2后根远端在硬脊膜囊内分别行显微缝合,同时修复重建膀胱的感觉与运动功能,建立人工膀胱生理反射弧.左侧不作任何处理.于术后5个月,在破坏L6～S4节段脊髓制备完全性截瘫前后,分别进行电生理检查及膀胱内压测定.结果 18只大鼠存活至术后5个月,9只大鼠成功分离出吻合的神经根,获得实验结果.实验侧截瘫前后,单相方波(3mA、0.3ms)刺激S2后根吻合口远端,均可记录到膀胱神经丛动作电位,波幅分别为(0.10±0.02)mV和(0.11±0.03)mV,差异无统计学意义(P>0.05);串刺激(3mA、20Hz、5 s)S2后根,均可记录到膀胱平滑肌复合肌肉动作电位,其波幅分别为(0.11±0.02)mV和(0.11±0.03)mV,差异无统计学意义(P>0.05).刺激S2后根吻合口远端,经新建的人工膀胱反射弧引出的膀胱内压分别为(6.55±1.33)cmH2O和(6.11±2.01)cmH2O,差异无统计学意义(P>0.05).对照侧截瘫前刺激S2后根,引出的膀胱神经丛动作电位波幅为(0.144±0.02)mV,膀胱平滑肌复合肌肉动作电位波幅为(0.17±0.02)mV,膀胱内压为(10.77±1.78)cmH2O,均大于实验侧截瘫前后(P<0.01).而电刺激对照侧截瘫后S2后根,不能引出膀胱神经丛动作电位、平滑肌复合肌肉动作电位,膀胱内压无变化.结论 利用截瘫平面以上健存的神经根,通过与硬脊膜内骶神经前后根分别吻合,可建立完整的人工膀胱反射弧,有望实现截瘫患者自主性排尿.

AN EXPERIMENTAL STUDY OF ESTABLISHMENT OF PHYSIOLOGICAL REFLEX ARC AFTER CONUS MEDULLARY INJURY IN RATS

OBJECTIVE: To establish an artificial physiological reflex arc with reconstruction of the sensory and the motorial functions of atonic bladder simultaneously after the conus medullary injury in rats. METHODS: Twenty 3-month-old male SD rats, with the weight of 250 to 300 g, were included. The right side was the experimental side, while the left side served as a control. Intradural microanastomosis of the right L5 ventral root to S2 ventral root and L5 dorsal root to S2 dorsal root was performed to reconstruct the sensory and the motorial functions of atonic bladder. After axonal regeneration, the new motor-to-motor and sensory-to-sensory artificial bladder reflex pathway was established. At 5 months postoperatively, the early function of the reflex arc was observed by electrophysiological examinations, and the bladder pressure was tested. RESULTS: Eighteen rats survived for 5 months after the operation. Single stimuli (3 mA, 0.3 ms) of the S2 dorsal root of the experimental side resulted in evoked potentials recorded from the right vesical plexus before and after the spinal cord was destroyed horizontally between L6 and S4 segmental levels. The amplitudes of the evoked potentials were (0.10 +/- 0.02) mV and (0.11 +/- 0.03) mV, respectively, before and after paraplegia, and there was no statistically significant difference (P > 0.05). The figures of the evoked potentials were similar to those of the control side. Bladder contraction was initiated by trains of stimuli (3 mA, 20 Hz, 5 s) of the S2 dorsal root of the experimental side. The bladder pressures were (6.55 +/- 1.33) cmH2O and (6.11 +/- 2.01) cmH2O, respectively, and the amplitudes of bladder smooth muscle complex action potential were (0.11 +/- 0.02) mV and (0.11 +/- 0.03) mV, respectively, before and after paraplegia. There was no significant difference (P > 0.05). These figures were similar to those of the control side before paraplegia. Before paraplegia, when the S2 dorsal root of the control side was stimulated, the amplitude of the evoked potential was (0.14 +/- 0.02) mV, the bladder pressures was (10.77 +/- 1.78) cmH2O and the amplitude of bladder smooth muscle complex action potential was (0.17 +/- 0.02) mV. There was statistically significant difference bewteen the experimental side and the control side (P < 0.01). All the results of electrophysiological examinations and bladder pressure were negative when the left S2 dorsal root was stimulated after paraplegia. CONCLUSION: Suprasacral nerve motor-to-motor and sensory-to-sensory transfers after the spinal cord injury to reconstruct the bladder autonomic reflex arc by intradural microanastomosis of ventral root and the dorsal root between L5 and S2 simultaneously is practical in a rat model and may have potential in clinical application.