测力神经根拉钩的实验应用

Experimental application of auxometric nerve root retractor

背景:神经根拉钩是腰椎间盘突出症髓核摘除和腰椎融合术中必需的器械,传统的神经根拉钩无法量化神经根的拉力,容易引起神经根的过度牵拉。目的:为防止腰骶神经根的牵拉性损伤,根据腰椎管和腰骶神经根的解剖学特点,拟研制一种可以测量神经根牵拉力的新型神经根拉钩。设计、时间及地点:随机对照,电生理动物实验,于2004-04/2007-10在江苏南通大学第二附属医院完成。材料:清洁级健康12周龄雄性大白兔40只,随机分为对照组、轻度牵拉组、中度牵拉组、重度牵拉组,10只/组。方法:测力神经根拉钩由带压力感受器的拉钩、固定支架和显示器3部分组成。拉钩通过固定支架与手术床固定,牵拉神经根的拉力通过显示器显示。各组兔均全椎板切除显露双侧骶1神经根,轻、中、重度牵拉组分别用测力神经根拉钩给予0.4N,1N,1.8N拉力水平牵拉左侧骶1神经根,对照组不牵拉。记录神经根牵拉比率,以神经根水平牵拉距离占椎管横径的百分比表示。在牵拉1,5,10min及去除牵拉后1,5,10min记录体感诱发电位潜伏期。主要观察指标:牵拉力与神经根牵拉比率、体感诱发电位P1波潜伏期的关系。结果:与轻度牵拉组比较,中、重度牵拉组神经根牵拉比率均显著升高(t=3.54,P<0.01)。与对照组比较,轻度牵拉组体感诱发电位P1波潜伏期无明显变化(t=1.48,P>0.05);中、重度牵拉组体感诱发电位P1波潜伏期均明显延长(t=2.48,P<0.05;t=4.15,P<0.01),神经根去除牵拉10min后,前者体感诱发电位P1波潜伏期接近正常(t=2.36,P>0.05),后者体感诱发电位P1波潜伏期缩短(t=3.86,P<0.05),且此时重度牵拉组体感诱发电位P1波潜伏期延长超过对照组潜伏期10%。结论:牵拉力越大,神经根牵拉比率越高,体感诱发电位潜伏期越长。应用带压力感受器的测力神经根拉钩比传统神经根拉钩安全可靠,可以最大程度牵拉神经根。

BACKGROUND： Nerve root retractor is necessary apparatus in nucleus pulposus removal of lumbar intervertebral disc protrusion and lumbar spinal fusion. Traditional nerve root retractor cannot quantize the tensile force of nerve root, resulting in excessive tension. OBJECTIVE： Based on the anatomic characteristics of lumbar spinal canal and lumbar-sacral nerve root, to design auxometric nerve root retractor that can measure the force of dragging nerve root and can avoid tractive lumbar-sacral nerve root injury in surgery. DESIGN, TIME AND SETTING： Randomized control and electrophysiological animal trial was performed at Second Hospital of Nantong University between April 2004 and October 2007. MATERIALS： Forty clean-grade 12-week-old healthy male rabbits were randomly divided into control, mild, moderate and heavy traction groups （n=10）. METHODS： The auxometric nerve root retractor consisted of retractors with pressoreceptor, clamp stand and display unit. The retractor was fixed through the clamp and operation table. The force of dragging nerve root was showed on the display. The first left sacral nerve root was dragged in different degrees of dragging force （0.4, l and 1.8 N） with a auxometric nerve root retractor after exposing the spinal cord entirely via bilateral laminectomy, then the ratio of dragging nerve root were measured. The latency of somatosensory evoked potentials （SSEP） was recorded before, 1, 5 and 10 minutes during the traction and after the traction. The control group was not dragged. MAIN OUTCOME MEASURES： Ratio of dragging force and nerve root retractor force; SSEP P1 latency. RESULTS： Compared with mild traction group, the ratio of traction ratio in the other two traction groups was significantly greater （t=3.54, P 〈 0.01）. There were no statistically significances in the latency of SSEP P1 wave between mild traction group and control group （t=1.48, P 〉 0.05）, but for the moderate and heavy traction groups, the latencies of SSEP P1 wave were significantly longer （t=-2.48, P 〈 0.05; t=4.15, P 〈 0.01）. The latency of SSEP P1 wave in the moderate traction group returned to normal level after 10 minutes of traction （t=2.36, P 〉 0.05）, while shortened in the heavy traction group （t=3.86, P 〈 0.05）. and the prolonging of the latency of SSEP P1 wave in the heavy traction group was 10% longer than the control group. CONCLUSION： Traction ratio of nerve root is increased with dragging force, so is latency of SSEP P1 wave. Auxometric nerve root retractor with pressoreceptor is more safe and reliable than traditional retractor. It may drag the nerve root to the maximum degree.