Modified Spared Nerve Injury Surgery Model of Neuropathic Pain in Mice

Summary

The modified surgery is a simplified method for mouse or rat spared nerve injury model that requires only one ligation and one cut to injure both common peroneal and sural nerves.

Abstract

Spared nerve injury (SNI) is an animal model that mimics the cardinal symptoms of peripheral nerve injury for studying the molecular and cellular mechanism of neuropathic pain in mice and rats. Currently, there are two types of SNI model, one to cut and ligate the common peroneal and the tibial nerves with intact sural nerve, which is defined as SNIs in this study, and another to cut and ligate the common peroneal and the sural nerves with intact tibial nerve, which is defined as SNIt in this study. Because the sural nerve is purely sensory whereas the tibial nerve contains both motor and sensory fibers, the SNIt model has much less motor deficit than the SNIs model. In the traditional SNIt mouse model, the common peroneal and the sural nerves are cut and ligated separately. Here a modified SNIt surgery method is described to damage both common peroneal and sural nerves with only one ligation and one cut with a shorter procedure time, which is easier to perform and reduces the potential risk of stretching the sciatic or tibial nerves, and produces similar mechanical hypersensitivity as the traditional SNIt model.

Introduction

Nerve injury-induced neuropathic pain following surgery or trauma has a significant economic burden that impairs quality of life. A host of nerve injury models, including spinal nerve ligation (SNL)¹, chronic constriction injury (CCI)² to the sciatic nerve, partial sciatic nerve ligation (pSNL)³, sciatic nerve transaction (SNT)⁴ and spared nerve injury (SNI)^5,6,7,8, were successfully developed to mimic the cardinal symptoms of peripheral nerve inj....

Protocol

Animal experiments were approved by UCSF Institutional Animal Care and Use Committee and were conducted in accordance with the NIH Guide for the Care and Use of Laboratory animals. Adult C57BL/6 mice weighing 20-30 g was used in this study. The von Frey assessment was performed between 1:00 pm and 3:00 pm.

1. Anesthesia and mouse preparation

1. Place a mouse in a plastic chamber filled with 2% isoflurane in O₂ at a flow rate of 1.0 L/min until it is fully a.......

Discussion

Compared to the traditional mouse SNIt method that ligates the common peroneal nerve and the sural nerve separately^6,7,8,9, the modified SNIt model has three advantages: (1) it has less risk of contracting or stretching sciatic or tibial nerves; (2) there is no need to remove the distal nerve stumps after nerve-cutting because by ligating the common peroneal nerve and the sural nerve together, .......

Materials

Name	Company	Catalog Number	Comments
6-0 suture	Henry Schein	9007482	Nerve ligation and close the muscular layer
Iris Scissors	Integra Miltex	12460598	Cut muscle and fascia
Mayo dissecting scissors	Fisherbrand	895120	Cut skin incision
Micro forcep	Fisherbrand	16100110	Blunt dissection biceps femoris muscle
Micro Scissors	Excelta	17467496	Cut nerve
Microdissection Forceps	Fisherbrand	16100123	Separate the common peroneal and the sural nerves from the neighboring tissues
Needle Holder	Fisherbrand	8966	Hold 6-0 needle
Prism software	Graph Pad	version 8.0	Statistical analysis software
Wound clips	Roboz Surgical	NC1878744	Close skin incision