Research Of Perioperative Neuroprotection Strategy And Innovative Optimization Of Neuromonitoring System During Thyroid Surgery

Recurrent laryngeal nerve（RLN）and intraoperative neurological impairment involving the external branch of superior laryngeal nerve（EBSLN）are recognized as one of the major complications of thyroid surgery in the world.Neuroprotection has undergone a hundred years of evolution,and our surgical predecessors have accumulated rich experience for us,which has greatly reduced the rate of nerve injury during thyroid surgery.Nevertheless,the review of foreign reports in the past ten years shows that the intraoperative injury rate of the recurrent laryngeal nerve can still reach 2.8%-12.3%,and the intraoperative injury rate of the external branch of superior laryngeal nerve can reach 0.45%-58%.In China,some scholars have reviewed and analysed this.In recent ten years,the rate of intraoperative recurrent laryngeal nerve injury in China is 2.23%-7.40%,and that of the external branch of superior laryngeal nerve is 1.2%-10%.The current situation of neurological protection in thyroid surgery is not optimistic.The neuroprotective methods under the guidance of empirical medicine can no longer cope with the increasing number of cases and the increasingly complex thyroid surgery.The emergence of intraoperative neuromonitoring（IONM）technology in thyroid surgery has brought neurological protection methods into the electrophysiological era.However,as far as its current use is concerned,IONM is still insufficient for extrathyroidal surgery.Receiver end has poor contact,indwelling difficulty,easy interference during operation,high false positive rate,and cannot adapt to unexpected operation;stimulus end indwelling process is cumbersome,demolition process is complex,and signal stability is poor,easy to fall off during operation,and is not suitable for endoscopic surgery;software aspect,the current system cannot exclude false positive results,can produce false negative results for early nerve injury,cannot monitor.Many problems,such as measuring the lower amplitude of EBSLN and neurological function,need to be solved urgently.In addition,there is no precise evidence-based guidance for the establishment of a complete neuroprotective system in the clinic,and the application methods and procedures vary from place to place in different institutions around the world and cannot be unified yet.In addition,in modern thyroid surgery,the high frequency application of energy instruments,rapid cutting,accurate haemostasis,improve surgeon confidence,make the scope of surgery expanded,and improve the accuracy of surgery.At the same time,the degree of negative impairment of neurological function by surgical intensity and thermal energy instruments is unknown,and intraoperative nerve injury is often"unexpected”.The intraoperative operation affecting neurological function is still uncertain;how to use energy devices safely and regularly in the operation to achieve complete tumour clearance and preserve neurological function is currently one of the focus of thyroid surgery research.Therefore,the mechanism of nerve thermal injury caused by energy devices and safe operation distance still need to be clarified,the software and hardware of the nerve monitoring system still need to be optimized,and the evaluation methods of vocal cord function in perioperative period need to be verified.This series of studies intends to simulate clinical surgery by animal nerve injury model,explore the temperature data of energy devices and the safe range of thermal injury by using IONM technology;carry out hardware optimization and improvement and software upgrade research and development of existing nerve monitoring equipment to make it more suitable for current surgical practice;verify the effectiveness of perioperative vocal cord function assessment means;establish a complete,accurate and instructive significance.To provide evidence for laryngeal nerve protection and evaluation in thyroid surgery in the future,and to guide clinical work.For the above content,this paper is mainly divided into seven parts:1.IntroductionTo introduces the research background and design ideas of this paper.2.Animal experiments:temperature of energy devices and safe distance of recurrent laryngeal nerve injuryConclusion:The application of EBD around the recurrent laryngeal nerve（RLN）during thyroid surgery increases the risk of RLN injury.Valley Ambipolar coagulation forceps,LigaSure^TMM coagulation clamp LF1212,Sonicision^TM cordless Ultrasound Knife and PEAK Unipolar Low Temperature Electrotome PlasmaBlade^TMM Excitation within 3 mm from RLNs significantly increased the nerve surface temperature and decreased the amplitude of EBMG,leading to decreased neurological function.Safe distance from RLN function protection in thyroid surgery for 4 EBDs with RLN 3 mm or more.3.Animal experiment:feasibility,stability and accuracy of thyroid cartilage needle electrodes in intraoperative neuromonitoring of thyroidConclusion:TC needle electrodes can obtain higher monitoring amplitude than ET surface electrodes,and the obtained EMG signal is more stable,less susceptible to intraoperative operation interference,and earlier identification of RLN injury.The ability of TC needle electrodes to obtain EMG signals was related to the location of insertion into the TC,with the optimal location located within 1 cm of the lower edge of the unilateral TC（area 4）.The ability of TC needle electrodes to obtain EMG signals was independent of the depth,angle and direction of TC insertion.4.Animal experiment:Feasibility and stability study of non-invasive receiving electrode in intraoperative nerve monitoringConclusion:The monitoring ability of NATCE on neurological function during thyroidectomy is consistent with that of ET surface electrode,and the obtained EMG signal is more stable and has stronger anti-interference ability.5.Animal experiments:performance study and superiority analysis of percutaneous stimulation electrode in intraoperative neuromonitoring of thyroid glandConclusion:The EMG signal generated by TSE electrode is caused by the percutaneous diffusion of current to the laryngeal muscle,which cannot be used in clinical work at present.6.Application of thyroid cartilage single needle receiving electrode in intraoperative nerve monitoringConclusion:TC needle-stick electrode is suitable for clinical work,can make up for the shortage of ET electrode,obtain more stable EMG signal and obtain more significant amplitude.7.Quantitative monitoring parameters of external branch of laryngeal nerve:area under EMG waveform and perioperative neurological function evaluationConclusion:In the functional monitoring of RLN and EBSLN in IONM,AUW is consistent with the ability of amplitude to respond to neurological function.Intraoperative assessment of EBSLN injury by AUW is more suitable for clinical work than amplitude parameters.