Study On Stability Of Response In Peripheral Nerve Electrical Stimulation

Spinal cord injury is a serious injury of the central nervous system.It is characterized by high morbidity,high disability,and high mortality,which has attracted widespread attention from the medical field and is also a global medical problem.In the past two decades,although there have been many advances in surgery,medicine,cell transplantation,and rehabilitation,the problems of loss of muscle function,sensation,and autonomic nerve function in the limbs have not been resolved.Therefore,engineering methods can effectively restore the normal function of patients’ limbs,but there are still some unresolved problems with these methods.This article focuses on the problem of poor stability that occurs when functional electrical stimulation of peripheral nerves is performed.This deterioration of stability will cause patients to often be unable to complete a stable action,such as raising their hands and taking objects.Therefore,revealing the reasons for the deterioration of the stability of peripheral nerve functional electrical stimulation has guiding significance for optimizing the design of electrical stimulation schemes and electrodes.The underlying mechanism and source of the decreased stability of functional electrical stimulation(FES)responses of peripheral nerves are still controversial.Currently,a commonly proposed hypothesis for this decreased stability phenomenon suggests that FES can cause disturbances to the membrane potential of neuronal cells locally,leading to fluctuations in the threshold voltage and resulting in an unstable intensity of mechanical response.In order to explore the alteration of the stability in electrical stimulation of peripheral nerves,preparations for functional electrical stimulation experiments of peripheral nerves were first carried out,including the construction of electrical stimulation platform,animal surgery preparation,and the design,manufacture and testing of implanted electrodes.During the electrical stimulation of the sciatic nerve bundle,it was found that repeated electrical stimulation under the same electrical stimulation parameters would lead to poor stability of the mechanical response.Therefore,the experimental instability was defined and calculated,and a "positive peak" of the instability curve was observed under varying stimulus current amplitudes,called the instability peak.Try to explain and avoid the instability peak,use the Circuit-Probability theory to explain the phenomenon of poor stability,and give a positive solution.This study found that,on the one hand,the results of electrical stimulation experiments can be well reproduced by simulation.This shows that the simulated model constructed can better explain the experimental phenomenon of electrical stimulation.Among them,the instability in electrical stimulation is indeed caused by threshold voltage fluctuations,and the source of unstable peaks is subthreshold oscillations generated by transmembrane electric fields under subthreshold stimulation.On the other hand,according to the simulation results of instability under different electrical stimulation parameters,a guiding scheme for dynamic adjustment of electrical stimulation parameters is proposed to improve the stability of peripheral neurofunctional electrical stimulation response.