Comparison of two methods for establishment of spared nerve injury model of chronic neuropathic pain

Objective To compare the pain threshold difference in spared nerve injury (SNI) model with or without amputating peroneal nerve after ligating it. Methods Thirty healthy male SD rats were randomly divided into three groups,ligation and amputation group (group A,n=10),ligation group (group L,n=10) and sham group (group C,n=10).In group A,the right peroneal nerve was amputaed after ligated by silk.In group L,the right peroneal nerve was simply ligated by silk.However,in group C,the right peroneal nerve was only exposed without any treatment.Mechanical withdrawal threshold (MWT) and thermal withdrawal threshold (TWT) of all rats were measured at different time points after modeling. Results The pain threshold of group A and group Ldecreased significantly over time (P<0.05) and tended to be stable from the seventh day after the operation.At the postoperative 7 day,compared with group C,MWT (2.33±0.36 g and 4.40±0.75 g vs 11.80±4.43 g) and TWT (33.50±1.29 ms and 36.75±1.26 ms vs 46.75±4.50 ms) of group A and group L were significantly lower (P<0.05,respectively),and the pain threshold of group A was significantly lower than that of group L. Conclusion Compared with the SNI model established only by ligating peroneal nerve,the pain threshold of the SNI model established by ligating and amputating peroneal nerve decreases significantly.