Studies On The Role Of Nucleus Pulposus In The Pathomechanism Of Sciatica

Sicatica is commonly and frequently encounered diseases, any lesion on the fullrange of sciatic nerve can result in sciatic4 such as periformis muscle syndrome,fractUre and dislocation of hip joint, injecting into buttocks l sicatic nerve injuries,nucleus pulposus protrUsion, canai stenosis, lurnbar spine instability yellow ligamentthickening, intracanal tUInor and so on. AInong these, nucleus pulposusprotrUsion is the most important and conunon reason, the tyPic syndrome of thispatients is low back pain combined with sicatica. The mechanical comPression wasconsidered the only reason of sicatica for a long time, but recent researches suggeStthat the biochemical factors of nucleus pulposus may play an driportant role on thepathomechanisms of sciatica. In order to elucidate the role of biochemical factors ofnucleus pulposus in the pathogensis of sciatica, the present research have potfOllowing four parts work on rats into operation.l.Considering limited condition, we refered to Kawakdri's method and bullt uPsciatica animal model by transplamed autologous nucleus pulposus of coccygealvertebral into rat's cavum epidUrale on the level comparing to L... On this model, wemeasured their pain-related behavior and observed pathologic changes of spinal nerveroots under light and electronic microscopy view2.Using electrophysiological teclmique, MEP, SEP F-WaVe, H-refiex changes weresurveyed on this model.3.Based on the anirnal model showed above, immunohistochemistry were used todetermine the change and distribution of SP and CGRP-positive neurons structUres indorsal root ganglia and dorsal hom of spinal cord.4.In order to find the role of PLA2 in the pathogensis of sciatica, we injected PLA2into rats' cavurn epidurale and mepacrine, the inhibitor of PLA2, into the cavurnepidurale of rats transplanted with aotologous nucleus pulposus, then changes of pain-related behavior and electrophysiology were observed.The results were discribed as follows:1The sensitivity to mechanical stimuli observed in the nucleus pulposus grouP issignificantly hypersensitive from third day to tWenty fourth day postoperatively, ascompared to control grouP and muscle grouP, but there was no significant change ofmechancal stimuli threshold in the control grouP and muscle grOuP postOpertivelyThe thermal withdrawl latency has no significant change in all three group afteroperation. Under ligh microscopic view the myelinated fibers in the control grouPdisplay normal morphology, the sPinal nerve roots in muscle group disPlay slighedema, but the morphology of nerve flbers is normal, no significan sheathdisintegration and necrosis aPpeared. The degeneration of spinal nerve roots innucleus pulposus grouP initiated on first week after transplanaion of aotologousnucleus pulposus; On second week, the degeneration become more seriously, mostsheaths disintegrated, ouly necrotic outline remains, the axons utterly disaPpeared andregeneration of nerve fibers emerged, On fourth week, sheath disintegration andnecortic contOur still exist; The regeneration of nerve fibers increased. Undere1ectronic microscopic vieW concentric circle structUre of sheaths in the nucleuspulposus obscured first week postopratively, layers become relaxed, distorted andirregUlar layer gaps broadened; On second week, wide demyelination of myelinatedflbers aPpeared, the axons become thickening, distorting, subsequently with axonsbreak and disappearance of intracellular organs, phagocytes infiltrating andregeneration of nerve fibers can be seen; On fodri week, significant deformation ofsheaths emerged, sheath layers decreased or obliterated, substituted with meshwork orsponge structUre, neogenesis of axon increased numerously2. The SEP and MEP axnplitUde of nucleus pulposus grouP decreased significanlyon the first,second and foUIth week postoperatively, as comPared tO muscle grouP andcontrol grouP, SEP amplitUde decreased significanly (P<0.05) on...