Experimental Study On Spinal Pathologic Changes And Axonal Regeneration After Repair Of Brachial Plexus Root Avulsion

Objective: In order to evaluate the operative possibility of rootsreimplantation and extraforaminal roots suture, and observe the impacton the neuron survival and axonal regeneration related to differenttiming of operation, we design observe the spinal pathology andaxonal regeneration in different time point after roots reimplantationand extraforaminal suture in the rat model of the brachial plexus rootsavulsion (C5-7) and extraforaminal roots transection (C5-7). Methods: the experiment included two parts. Part 1 After establishing the rat model of brachial plexus rootavulsion, we performed the following experiments. Group A: the avulsed roots were reimplanted into the spinal cordimmediately. At the different time point (3w, 3m, 6m), throughpathological examination and immunohistological techniques andnerve tracing techniques, we examined the spinal cord and distal nervetrunk in order to observe the pathologic changes and axonalregeneration. Group B: The roots were reimplanted into the spinal cord indelayed 3 weeks after the roots were avulsed. The examinations werethe same as the above. Part 2: after establishing the rat model of extraforaminal roottransection, we performed the following experiments:Group C: The transected roots were sutured to the proximalstump immediately and examined according to the measures above.Group D: The suture was delayed 3 weeks and the examinationswere the same as the groups above.Results:1,in the rat model of brachial plexus root avulsion, the generalconditions were poor, the hair was not bright and presented depilation.The weight lost. 3 cases presented ulcer and limped.2,in the rat model of brachial plexus root avulsion, the numbersof neuron decreased, the residual cell bodies enlarged, and the Nisslbody and nucleus dissolved. The numbers of neuron, Nissl body andnucleus were fewer in 3 m than in 3 w, but there was no significantchanges in 6 m compared with in 3 m. in group A, the rate of neuronnecrosis in the anterior horn reached 40% in 6 m, and in group B, therate reached 80%. The residual neuron presented injured phenomena.In groups C and D, the necrosis rate reached 30-40%, and the residualneurons were pathologic.3,the nerve trunk presented no significant changes. In groups Aand B, the diameter of the distal trunk decreased. But in groups C andD, the diameter of the distal trunk decreased significantly. Throughhistological examination, wallerian degeneration was observed inevery group. The regenerated axon was thin. In group A and B, nervefibers of positive stain presented in 3 w, about 15%, but increased in 3m, about 30%, and in 6m, the fibers increased significantly, about 40%.In group C and D, no fibers of positive stain presented in 3 w, but 35%of positive stain presented in 3 m, and 45% presented in 6m.4,the results of nerve trace: fibers density of positive label ingroup A was higher than in group B. Confocal microscopy: thefluorescence accumulation in group A is higher than in group B。Closeto the near end, the more obviously the myelin is coloured, it is thickfor axle;carry far, it is the less obvious for myelin to colour and tinyfor axle, axle breaked down suddenly can be seen, the fluorescenceaccumulation distribution in Confocal microscopy appears thecharacteristic described above also together. The myocutaneous nerveat the places of entering muscle, two groups do not have obviousdifference by slice serially, and the marked neural myelin and axle canbe seen by accidental. the changes of group C, D appear similar togroup A, B, nerve fibre of mark count, fluorogenic material gatherintensity at the same neural level positive higher than group A, Bslightly just, the neural segment of the positive mark is slightly long ingroup A, B too in length. The positive mark neuraxis at themyocutaneous nerve at the places of entering muscle can be seen byaccidental, but not be seen myelin mark.1,there was no significant changes in muscle weight of brachiibiceps between 3w and 3min every group, but no significant changesin 6m. in 3m, the muscle weight of brachii biceps in groups A and Bwas different from it in groups C and D. HE stain: in 3w, the musclepresented degeneration and the cross area decreased. In 3m, thereexisted significant difference in every group, in 6m, the muscledegeneration disappeared.Conclusions:1,the neuron in the anterior horn can re-enter the reimplantednerve trunk, and the regenerated fibers reached 40%.2,the regenerated fibers presented incomplete regeneration andthe dynamic power of regeneration is insufficient.3,regeneration didn't exist in the myocutaneous nerve during 6min the rat model of brachial plexus root injury.4,early repair of the injured nerve had the advantage ofprotecting the injured nerve and the neuron in the anterior horn.5,the functional recovery of brachii biceps was not the basis ofevaluating the distance of the nerve regeneration in C5-7 injury.