Establishment of an animal model of sacral nerve root avulsion in rats

Objective To establish an animal model of sacral nerve root avulsion in rats and e-valuate its efficiency. Methods A total of 20 adult SD rats (either sex) were chosen at random to es-tablish the sacral nerve root avulsion model by avulsing the fight L4-6 nerve roots out of intervertebral fo-ramina without laminectomy. The left side was set as control group. The models were evaluated in aspects of survival rate, Basso-Beattie-Bresnahan (BBB) scores, somatosensory evoked potential (SEP), horse radish peroxidase (HRP) tracing, bilateral weight and cross section area (CSA) of muscle biceps femo-ris, fiber of triceps surae and anterior tibial muscle. Results Of all, 19 rats were survived but one died, with survival rate of 95.0%. The BBB score was (10.78+3.15) points in experimental group and 21 points in control group. The success rate of establishing animal model was 89.5% ,for there detected no SEP in bilateral cerebral cortex of the wounded extremity of 17 rats. HRP showed positive reaction in the spinal segment of L4-6 in two rats but negative in 17, with success rate of 89.5%. There was statistical difference in aspects of weight and muscle fiber CSA of double biceps femoris, triceps surae and anterior fibial muscle between experimental group and control group. Electron microscope found denervation chan-ges including muscle fiber atrophy, nucleus shifting to (center and muscle satellite cell. Conclusion A-vulsion of L4-6 sacral nerve root out of vertebral canal is a feasible and ideal method to establish the avui-sion model of sacral nerve root injury in rats. Key words: Lumbosacral plexus;  Rats;  Avulsion