The effect of Spinal Cord Stimulation in mice with chronic neuropathic pain after partial ligation of the sciatic nerve.

The effect of Spinal Cord Stimulation (SCS) in chronic neuropathic pain is inversely related to the severity of mechanical allodynia and the underlying mechanisms are poorly understood. To understand these mechanisms further we aimed to develop a model of SCS in a neuropathic mouse. Further, the CatWalk analysis, which is claimed to be an improved test for mechanical allodynia and therapeutic intervention, was used to analyze the effect of SCS on mechanical allodynia. Male C57BL/6 mice (N=31) underwent partial ligation of the sciatic nerve. After 14days an electrode was implanted and the effect of SCS (N=22) on mechanical allodynia was tested. Unligated mice (N=8) also received SCS. Behavioral analysis was performed using von Frey filaments and the CatWalk system. The withdrawal threshold showed a significant decrease which remained over time. Changes in CatWalk parameters were observed after 2days, but tended to diminish during the next 14days. Thirty minutes of SCS resulted in a 100% response and return to pre-neuropathy levels of the withdrawal threshold. The effect of SCS on the withdrawal threshold was comparable for the most severe and milder allodynic animals. SCS did not affect any of the CatWalk parameters in all mice. In conclusion, we developed a model of SCS in a chronic neuropathic pain C57BL/6 mouse. The CatWalk gait analysis does not result in the detection of behavioral changes to SCS in mice with chronic neuropathic pain and control animals. This model allows future molecular-genetic studies on the mechanisms of SCS in chronic neuropathic pain.