The Impact Of Epidural Electrical Stimulation On Spinal Cord Motoneuron And Axon Regeneration After Sciatic Nerve Transection

Objective To observe the effect of epidural electrical stimulation on spinal cord motoneuron and axon regeneration after sciatic nerve transection and the results will be helpful to guide the clinical application of epidural stimulation on peripheral nerve injury.Methods 30 normal male SD rats at the age of 8 weeks,which weight 200-230 gram,were randomly divided into2 groups.The right sciatic nerve of each was cut off and the two ends of the nerve were coincided inversion.The group A was experimental group,which was inserted epidural stimulator on the correspond segments of spinal cord.The group B was control group,which was inserted the same stimulator but no output current.Injected antibiotics prevently for 5 days and observed the acras,hairs,gaits,unfold claw reflect,et al.Calculated the sciatic nerve function index(SFI) by measuring the podogram length(PL),width between the first and fifth toes(TW),inter-toesdistance(IT) of the normal and the experimental claws,at2w,4w,6w and 8 w after operation.Measured the nerve conduction velocity(NCV) of the right sciatic nerve in the electromyogram room at 2w,4w and 8 w after operation;and then executed the rats and detectioned the following indexs:(1) the humid weight of the triceps surae Scraped the triceps surae tightly,rejected surface connective tissue,blotted surface blood and weight ultimately.(2)the thickness of the myelin sheat of the regenerated sciatic nerve fiber Made the ultrathin sections by embedded and dyed with lead citrate,and then observed the regenerated sciatic nerve fiber and measured the myelin sheat by transmission electron microscope(JEM 21200E).(3)counted the number of neurons of anterior horn of spinal cord and observed it' s ultrastructure Sliced the spinal cord which was fixed by 4% paraformaldehyde to 5μm,dyed with HE,and then counted the number of neurons of anterior horn of spinal cord by light microscope at 400 times. Observed ultrastructure of the motoneuron by transmission electron microscope(JEM 21200E) ultimately.In the end,we compared and analyzed the experimental results between each group with t test by SPSS statistics software(P＜0.05).Results(1) General state of health All the rats survived after operation,no infection and distance limbs ulcer,the hairs had no significant differences,but show tug toes or jumped gait situation.The gait and unfold claw reflect began to recovery at 4w and 5w after operation in the experimental group,and in the control group at 6w and 7w after operation.(2) Calculated the sciatic nerve function index(SFI):Compared group A,the SFI was lower in the group B,and the results was significant difference(P＜0.05),at 2w,4w,6w and 8w after operation.(3) Nerve conduction velocity(NCV):The nerve conduction velocity(NCV) was increased significantly in both group A and group B,and the NCV was faster in the group of A than that in the group of B(P＜0.01),at 2w,4w and 8w after operation.(4) The humid weight of the triceps surae:The humid weight of the triceps surae was decreased in both group A and group B.Compare group A,the humid weight of the triceps surae was lower in the group B,and the results was significant difference(P＜0.05),at2w,4w and 8w after operation.(5) The thickness of the myelin sheat of the regenerated sciatic nerve fibers:Both of the groups had the regenerated sciatic nerve fibers.Compared group B,group A had more myelinated nerve fiber,thicker and well-distributed myelin shear,and no layers split or vacuolization. The thickness of myelin sheath of regenerated nerve fibers in sciatic nerve was increased significantly in group A than that in group B and was thicker in the group A than that in the group B(P＜0.01) at 4w and 8w after operation..(6) Counted the number of neurons of anterior horn of spinal cord and observed it's ultrastructure:In the group A,the organelles in cytoplasm of the neurons of anterior horn of spinal cord arranged regularly, mitochondria had normal structure,nuclear membrane was clear and the chromatin was well-distributed.And only a few,the nuclear membrane was concave in some area and chromatin agglutination.Some neuronal cell bodies shrunk obviously,and vacuoles emerged obviously in the cytoplasm, mitochondria lost their cristea,and nucleus shrunk and sunk in the control group.The number of neurons of anterior horn of spinal cord in group A was more than that in group B(P＜0.05).Conclusions:(1) Epidural pulse-electrical stimulation could prevent the apoptosis of perikaryon and protect the normal structure of the motoneurons of anterior horn of spinal cord.(2) Epidural pulse-electrical stimulation could promote the axon regeneration of the nervus peripheralis effectively.(3) Epidural pulse-electrical stimulation could prevent neuratrophia of the muscle after peripheral nerve injury.