The Analysis And Application Of Quantitative Parameters Of Intraoperative Neuromonitoring (IONM) In Thyroid Surgery

Objective:The quantitative parameters of a series of intraoperativeneuromonitoring (IONM) cases were analyzed for distinguishingnonrecurrent laryngeal nerve (NRLN) and a normal recurrent laryngealnerve (RLN).Backgroud:The anatomical structures of NRLNs are shorter thanRLNs,this diversity should result in differential latencies whenstimulating vagus nerve,which could be used as a method fordistinguishing an NRLN from an RLN at the early stage ofoperation.Dissecting of thyroid without early identification of NRLNseverely increases the risk of nerve injury.Methods:5cases of NRLN were detected after vagus stimulationbefore dissection by spotting significantly shortened latencies comparedto93controls (p<0.001).The electromyographic (EMG) signal wererecorded and the anatomical structures of NRLN were photographed byhigh-resolution camera.Results:All5NRLNs were detected only in the right neckregion.NRLN cases had significantly shortened latencies thancontrols(2.23ms vs.3.78ms,medians;p<0.001).All NRLNs were totallydissected and completely exposed to identify a visual integrity of the nerve,and EMG signals were identified again at the end of operation toensure final nerve function,and postoperative laryngoscope indicated novocal cord palsy occured.Conclusions:When implementing nerve stimulation before dissection anda significantly shortened readings of evoked EMG latency may imply anNRLN,which means the surgeon should pay special attention to theanatomical structures of current case by dissecting and exposing NRLNto avoid nerve injury.