Intraoperative Neuromonitoring In Thyroid Surgery Research Articles

Alternative Techniques for Intraoperative Neuromonitoring in Thyroid Surgery

Intraoperative Neuromonitoring (IONM) using endotracheal tube with surface electrodes has gain acceptance as an adjunct tool to preserve the recurrent laryngeal nerve in thyroid surgery. The electromyographic (EMG) tube based IONM has many advantages and is well validated, but it also has some disadvantages. This article is written to review alternative techniques for IONM in thyroid surgery except EMG tube.

Investigation of attachment location of adhesive skin electrodes for intraoperative neuromonitoring in thyroid surgery: Preclinical and clinical studies

BackgroundRecently, adhesive skin electrodes have been reported to be useful for recording electromyographic signals from intrinsic laryngeal muscles for intraoperative neuromonitoring in thyroid surgery and have shown good results compared to existing recording methods. In this study, we investigated the optimal attachment location of adhesive skin electrodes for intraoperative neuromonitoring in both porcine models and human cases. MethodsAttachment locations were divided vertically into upper, middle, and lower locations and horizontally into medial and lateral locations to determine the optimal location of placing adhesive skin electrodes preclinically in four porcine models. This study included a total of 78 patients who underwent thyroidectomy under intraoperative neuromonitoring with adhesive skin electrodes. Sixteen patients were monitored using both adhesive skin electrodes and an electromyographic endotracheal tube. Two pairs of skin electrodes were attached to the level of the thyroid cartilage lamina. Evoked electromyographic data, including data on mean amplitude and latency, obtained by stimulating the recurrent laryngeal nerve and vagus nerve, were collected. ResultsLateral attachment of adhesive skin electrodes showed significantly higher evoked amplitudes than medial attachment in both animal models and human patients. In cases where skin electrodes and an electromyographic endotracheal tube were used together, the electromyographic endotracheal tube showed a significantly higher amplitude than skin electrodes, and laterally attached skin electrodes showed a significantly higher amplitude than medially attached skin electrodes. ConclusionIntraoperative neuromonitoring using adhesive skin electrodes was feasible in both animal models and human patients. We suggest that it would be better to attach adhesive skin electrodes to the lateral side of the thyroid cartilage lamina. Lateral attachment closer to the cricoarytenoid joint may be better for measuring muscle movement around the cricoarytenoid joint.

Comparison of Monopolar and Bipolar Stimulator Probes for Intraoperative Nerve Mapping During Thyroidectomy: A Prospective Study.

During intraoperative neuromonitoring in thyroid surgery, two different kinds of stimulator probes, monopolar and bipolar, are commonly used to stimulate the laryngeal nerves. We explore the unique characteristics of both of these probes as they relate to intraoperative laryngeal nerve mapping. Twenty-one patients undergoing neuromonitored thyroidectomy by a single surgeon were enrolled. Electromyography (EMG) amplitude and latency measurements were prospectively recorded concurrently from 1 mA stimulation of vagus nerve (VN) and inferior/superior recurrent laryngeal nerve before (with and without fascia) and after thyroid resection using bipolar and monopolar stimulator probes. Significantly higher amplitudes were obtained with monopolar stimulator probes as compared to bipolar probes, in several stimulation scenarios such as at right VN pre-resection (carotid sheath intact), right VN pre-resection (carotid sheath dissected), right VN post-resection and left VN (carotid sheath dissected). No significant differences were found between amplitudes and latency values in all other stimulation scenarios. According to this study, both probes are reliable and safe for neural mapping. The kind of probe used during neural monitoring is based on surgical situations and surgeon preference. 3 (According to Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence) Laryngoscope, 131:E2718-E2726, 2021.

Comparison of Sugammadex Dose for Intraoperative Neuromonitoring in Thyroid Surgery: A Randomized Controlled Trial

To compare effect of 1 and 2 mg/kg of sugammadex on the incidence of intraoperative bucking and intraoperative neuromonitoring (IONM) quality in thyroid surgery. Randomized controlled trial. Patients qualified for thyroid surgery with IONM were eligible for this double-blind, randomized, controlled trial. After tracheal intubation with 0.6 mg/kg rocuronium, 1 or 2 mg/kg of sugammadex was administered to patients in group I or II, respectively. The quality of the IONM for the external branch of the superior laryngeal nerve (EBSLN) was evaluated (strong/intermediate/weak). The initial amplitude of electromyography for the vagus nerve (V1) and the recurrent laryngeal nerve (R1) were recorded. Intraoperative bucking movements was recorded. A total of 102 patients (51 in each group) completed the study. Time from sugammadex administration to initial checking for the EBSLN was not different between group I and II (25.0 ± 7.9 vs. 25.5 ± 9.0 minutes, P=.788). There was no difference in the neuromonitoring quality for the EBSLN between group I and II (strong/intermediate/weak: 46/5/0 vs. 50/1/0, P=.205). The amplitudes of V1 (1,086.3 ± 673.3 μV vs. 1,161.8 ± 727.5 μV, P=.588) and R1 (1,328.2 ± 934.1 μV vs. 1,410.5 ± 919.6 μV, P=.655) were comparable between the groups. Patients who experienced bucking were significantly fewer in the group I than the group II (13.7% vs. 35.3%, P=.020). A dose of 1 mg/kg sugammadex induced less bucking than 2 m/kg while providing comparable IONM quality during thyroid surgery. 2 Laryngoscope, 131:2154-2159, 2021.

Influence of rocuronium on achieving optimal vagal stimulation during intraoperative nerve monitoring in thyroid surgery

BackgroundIn the present study we determine the feasibility of intraoperative neuromonitoring following the administration of a nondepolarizing neuromuscular blocking agent during thyroid operations, as well as the influence of rocuronium on the achievement of optimal vagal stimulation during intraoperative neuromonitoring in thyroid surgery. We further investigate whether accelerometry is a reliable approach to obtaining an ipsilateral vagus signal prior to recurrent laryngeal nerve dissection. MethodsIncluded in the study were 61 thyroidectomized patients whose demographic data, indications, type of surgery, vagus, and recurrent nerve values before and after resection were obtained. We created five groups of patients based on the twitch values recorded during ipsilateral vagus stimulation prior to the recurrent laryngeal nerve dissection: (1) <10%, (2) 11–25%, (3) 26–50%, (4) 51–75% and (5) >75%. ResultsThe average electromyography amplitudes of the vagus nerve prior to the determination of the recurrent laryngeal nerve for each group were 552 μV, 463 μV, 543 μV, 513 μV and 551 μV, respectively. No difference between the groups was observed in this regard (p > 0.05). ConclusionIt can be expected that as soon as the effects of neuromuscular blockers on the peripheral muscles begin to abate, it will be possible to obtain the ipsilateral vagus signal prior to recurrent laryngeal nerve dissection at the desired levels. It can be concluded from this study that accelerometry using the pollicis muscle is an unreliable tool for the interpretation of the proper electromyography signals of the vagus nerve prior to the determination of the recurrent laryngeal nerve.

Ultrasound visualization of the vagus nerve for intraoperative neuromonitoring in thyroid surgery.

Localization of the vagus nerve is required during intraoperative neuromonitoring (IONM) for thyroid surgery in order to electromyographically verify the functional integrity of inferior laryngeal nerve and aim to reduce the risk of postoperative vocal fold paralysis. Classically, the vagus nerve courses within the carotid sheath between the common carotid artery and internal jugular vein, but anatomic variations have been described. Our aim was to compare preoperative ultrasound (US) and intraoperative localization of vagus nerve and to document anatomic variations. Retrospective study of patients undergoing thyroidectomy. The vagus nerve was identified 2 cm below the inferior border of the cricoid cartilage, on US performed 6 weeks prior to surgery; then, vagus nerve was identified surgically. For 82 patients, on preoperative US, the right vagus nerve was in between, superficial, or deep to the vessels in 94%, 2.4%, and 3.6%, and on the left in 72%, 24.4%, and 3.6%. Intraoperatively, the right vagus was in between, superficial, or deep in 90%, 4%, and 6%, and on the left in 67%, 27%, and 6%. US correlated with surgery on the right in 79/82 (96%) and on the left in 78/82 (95%). To our knowledge, this is the first study directly comparing US and intraoperative findings. The US and surgical findings were identical in 95% on the left and 96% on the right The vagus nerve was superficial in 27% of cases on the left and 4% on the right. Identifying this anatomic variation preoperatively may facilitate IONM. • Localization of the vagus nerve is necessary during thyroid surgery when using neuromonitoring for electromyographic testing of the inferior laryngeal nerve to reduce the risk of postoperative vocal fold paralysis. • The vagus nerve in the neck can be routinely visualized using ultrasound, and is generally in between the common carotid artery and the internal jugular vein. Its location on ultrasound corresponds very closely to that observed in vivo during surgery (95%). • At the level of the thyroid lobe, there is an anatomic variant with the vagus nerve superficial to the common carotid artery which is seen more often on the left than on the right.

Intraoperative Neuromonitoring in Thyroid Surgery: An Efficient Tool to Avoid Bilateral Vocal Cord Palsy.

This study aimed to analyze the effects of intraoperative neuromonitoring (IONM) on the prevalence of vocal cord palsy (VCP) in thyroid surgery. Data from 493 patients (839 nerves at risk [NAR]) who underwent thyroid surgery between July 2014 and May 2016 were retrospectively evaluated. The patients were divided into 2 groups: Group 1 (G1) consisted of patients who underwent surgery without IONM, whereas group 2 (G2) consisted of patients who underwent surgery with IONM. The surgical techniques were identical, and experienced surgeons performed the procedures in both groups. Intraoperative neuromonitoring was performed in compliance with the International Neural Monitoring Guidelines. In total, 211 patients (170 female, 41 male) with 360 NAR were included in G1, and 282 patients (220 female, 62 male) with 479 NAR were included in G2. The number of VCP per NAR in G1 and G2 was 33 (9.2%) and 27 (5.6%), respectively (P = .005). The number of transient VCP per NAR in G1 and G2 was 27 (7.5%) and 23 (4.8%; P = .230), respectively. The number of permanent VCP per NAR in G1 and G2 was 6 (1.7%) and 4 (0.8%; P = .341), respectively. Bilateral VCP was detected in 4 (2.7%) patients in G1, whereas there was no patient with bilateral VCP in G2 (P = .033). Intraoperative neuromonitoring may decrease the incidence of total VCP and prevent the development of bilateral VCP, which has unfavorable results for both patients and health-care professionals.

Neural monitoring in thyroid surgery is here to stay.

The iatrogenic injury of the recurrent laryngeal nerve (RLN), more clinically significant than those affecting the external branch of the superior laryngeal nerve (EBSLN), constitute one of the most feared perioperative complications of thyroid surgery and parathyroid glands, in terms of impact in clinical and economic-social costs. Moreover, these events rank among the leading reasons for medicolegal litigation of surgeons because of its attendant reduction in quality of life. The average incidence of RLN paralysis, permanent and temporary, after thyroidectomy is high and stands between 2.3% and 9.8% respectively. Given the elements described above, it is essential for the surgeon to adhere to a carefully standardized intraoperative technique that minimizes the possibility of RLN injuries. Intraoperative neuromonitoring (IONM) was introduced to reduce RLN injuries and for this reason, it achieved considerable success among endocrine surgeons. However, even today it is considered an adjunct device to the direct identification of the RLN. In this perspective, IONM of RLN constitutes an important aid, since it represents a reliable tool for the evaluation of functional neural integrity. Despite the ever-increasing diffusion of the IONM, prospective randomized studies are needed for further validation. The purpose of this work is to analyze scientific evidence to show that IONM in thyroid surgery is here to stay.

Poor Man&amp;#39;s Intraoperative Neuromonitoring in Thyroid Surgery

Poor Man&amp;#39;s Intraoperative Neuromonitoring in Thyroid Surgery

Effect of intraoperative neuromonitoring on efficacy and safety using sugammadex in thyroid surgery: randomized clinical trial.

PurposeThe use of nondepolarizing neuromuscular blocking agents (NMBAs) may affect intraoperative neuromonitoring (IONM) during anesthesia used during thyroid and parathyroid surgery.MethodsThe use of sugammadex was evaluated in a prospective clinical study during thyroid surgery. Between July 2018 and January 2019, 129 patients were prospectively randomized to either the sugammadex group (group B) or the control group (group A). Group A patients underwent standardized IONM during thyroidectomy, while group B patients used an NMBA-reversal protocol comprised of rocuronium (0.6 mg/kg) in anesthesia induction and sugammadex (2 mg/kg) after first vagal stimulation (V0). A peripheral nerve stimulator was used to monitor the neuromuscular transmission.ResultsIn our clinical study, it took 26.07 ± 3.26 and 50.0 ± 8.46 minutes to reach 100% recovery of laryngeal electromyography at injection of the sugammadex group (2 mg/kg) and the control group, respectively (P < 0.001). The train-of-four ratio recovered from 0 to >0.9 within 4 minutes after administering 2 mg/kg of sugammadex at the beginning of resection. Surgery time was significantly shorter in group B than in group A (P < 0.001). Transient recurrent laryngeal nerve (RLN) paralysis was detected in 4 patients from group A and in 3 patients from group B (P = 0.681). There was no permanent RLN paralysis in the 2 groups.ConclusionOur clinical study showed that sugammadex effectively and rapidly improved the inhibition of neuromuscular function induced by rocuronium. The implementation of the nondepolarizing neuromuscular block recovery protocol may lead to tracheal intubation as well as favorable conditions for IONM in thyroid surgery.

Sequential method for determining the maximum dose of mivacurium continuously infused for intraoperative neuromonitoring in thyroid surgery

To determine the maximum dose of continuously infused mivacurium for intraoperative neuromonitoring and observe its adverse effects in thyroid surgery. Twenty-eight patients undergoing thyroid surgery with intraoperative neuromonitoring received continuous infusion of mivacurium at the initial rate of 5.43 μg?kg-1?min-1, and the infusion rate for the next patient was adjusted based on the response of the previous patient according to the results of neurological monitoring. The depth of anesthesia was maintained with sevoflurane and remifentanil during the surgery. The LD50 and 95% CI of mivacurium were calculated using Brownlee's up-and-down sequential method. The LD50 of continuously infused mivacurium was 8.94 μg?kg-1?min-1 (95% CI: 8.89- 8.99 μg?kg-1?min-1) during thyroid surgery, which did not affect neurological function monitoring. Transient chest skin redness occurred after induction in 9 patients (32.1%). None of the patients experienced intubation difficulties or showed intraoperative body motions during the surgery. In patients undergoing thyroid surgery under anesthesia maintained by inhalation and intravenous infusion, the LD50 of mivacurium was 8.94 μg?kg-1?min-1 (95% CI: 8.89-8.99 μg?kg-1?min-1) for continuous infusion, which does not cause serious adverse effects during the operation.

갑상선수술에서 수술 중 신경 감시의 유용성

갑상선수술에서 수술 중 신경 감시의 유용성

갑상선 수술을 위한 실시간 지속적 신경생리검사

갑상선 수술에서 반회후두신경(recurrent laryngeal nerve) 손상을 예방하기 위해서는 반회후두신경를 직접 확인하는 것이 최선의 방법이다. 이와 더불어서 수술 중 신경감시(intraoperative neuromonitoring, IONM)가 소개되어 갑상선 수술에서 간헐적인 수술 중 신경감시 (intermittent IONM, I-IONM) 기술이 많이 사용되고 있다. 미주신경(vagus nerve) 혹은 반회후두신경에 전 기적 자극을 가하여 성대 근육(vocalis muscle) 가까이 위치한 전기 탐침(electrode)를 통해 성대 근육의 근전 도(electromyography) 측정한다. 근전도 신호의 변화를 음향학적 신호 혹은 모니터를 통해 시각화하여 수술 중 신경의 완전성(integrity)와 기능에 대한 정보를 수술자 에게 제공한다. 최근 사용되고 수술 중 신경감시 장치 는 전기 탐침을 기관 튜브에 일체화 시킨 제품으로 기 존 신경감치 장치에 비하여 사용하기 쉽고 편리하다.

Transcutaneous Recording During Intraoperative Neuromonitoring in Thyroid Surgery.

Recurrent laryngeal nerve (RLN) palsy remains a major source of morbidity after thyroid surgeries. Intraoperative neural monitoring (IONM) has gained increasing acceptance as an adjunct to standard practice of visual RLN identification. Endotracheal tube (ETT) surface recording electrodes systems are now widely used for IONM; however, a malpositioned ETT can cause false IONM results and requires time-consuming intraoperative verification of the ETT position and readjustment by the anesthesiologist. The aim of this experimental study was to evaluate the feasibility of the transcutaneous approach for recording evoked laryngeal electromyography (EMG) signals during IONM. A porcine model with well-established applicability in IONM research was used. Twelve piglets (24 nerve sides) were enrolled. Electrically evoked EMGs were recorded from surface electrodes on the ETT and from the adhesive pre-gelled surface electrodes on the anterior neck skin. The evoked EMG waveforms were measured and analyzed. The real-time signal stability of the electrodes during tracheal displacement and their accuracy in reflecting adverse EMG changes during RLN stress were evaluated during continuous IONM performed with automatic periodic vagus nerve (VN) stimulation. In all nerves, both the ETT and neck adhesive skin electrodes successfully recorded typical evoked laryngeal EMG waveforms from the RLNs and VNs under stimulation with 1 mA. The transcutaneous electrodes recorded mean EMG amplitudes of 264 μV (±79) under RLN stimulation and 202 μV (±55) under VN stimulation. The electrodes recorded mean EMG latencies of 2.98 ms (±0.20) under RLN stimulation, 4.51 ms (±0.50) under right VN stimulation, and 8.13 ms (±0.94) under left VN stimulation, respectively. When tracheal displacement was experimentally induced, the EMG signals obtained by ETT electrodes varied significantly, but those obtained by transcutaneous electrodes did not. When RLN traction stress was experimentally induced, both ETT and transcutaneous electrodes recorded the same pattern of progressively degrading EMG amplitude with gradual recovery after release of traction. This study confirms the feasibility of transcutaneous recording of evoked laryngeal EMG during IONM. Although this study confirms the stability and accuracy of the transcutaneous approach, it also revealed the need for new electrode designs to improve EMG amplitudes before practical clinical application of this approach.

Intraoperative Neuromonitoring in Thyroid Surgery

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Intraoperative neuromonitoring in thyroid surgery

Abstract Background Intraoperative neuromonitoring of the recurrent laryngeal nerve in thyroid surgery facilitates the identification of anatomical structures in cervical endocrine surgery reducing the frequency of vocal cord paralysis. Objective To study the normal electrophysiological values of the vague and recurrent laryngeal nerves before and after thyroid surgery. To compare rates of injury of recurrent nerve before and after the introduction of the intraoperative neuromonitoring in thyroid surgery. Material and methods An observational, descriptive and prospective study in which a total of 490 patients were included. Between 2003 and 2010, surgery was performed on 411 patients (703 nerves at risk) with systematic identification of recurrent laryngeal nerves. Between 2010 and 2011 neuromonitorisation was also systematically performed on 79 patients. Results Before the introduction of intraoperative neuromonitoring of 704 nerves at risk, there were 14 recurrent laryngeal nerve injuries. Since 2010, after the introduction of the intraoperative neuromonitoring in thyroid surgery, there has been no nerve injury in 135 nerves at risk. Conclusions We consider the systematic identification of the recurrent laryngeal nerve is the ‘gold standard’ in thyroid surgery and the intraoperative neuromonitoring of nerves can never replace surgery but can complement it.

Intraoperative neuromonitoring in thyroid surgery: Is the two-staged thyroidectomy justified?

BackgroundThe aim of this study was to evaluate the diagnostic accuracy of intraoperative neuromonitoring (IONM) in predicting postoperative nerve function during thyroid surgery and its consequent ability to assist the surgeon in intraoperative decision making. Materials and methodsA total of 2365 consecutive patients were submitted to thyroidectomy by the same surgical team. Group A included 1356 patients (2712 nerves at risk) in whom IONM was utilized, and Group B included 1009 patients (2018 nerves at risk) in whom IONM was not utilized. ResultsIn Group A, loss of signal (LOS) was observed in 37 patients; there were 29 true positive, 1317 true negative, 8 false positive, and 2 false negative cases. Accuracy was 99.3%, positive predictive value was 78.4%, negative predictive value was 99.8%, sensitivity was 93.6%, and specificity was 99.4%. A total of 29 (2.1%) cases of unilateral paralysis were observed, 23 (1.7%) of which were transient and 6 (0.4%) of which were permanent. Bilateral palsy was observed in two (0.1%) cases requiring a tracheostomy. In Group A, 31 (2.3%) injuries were observed, 25 (1.8%) of which were transient and 6 (0.4%) of which were permanent. In Group B, 26 (2.6%) unilateral paralysis cases were observed, 20 (2%) of which were transient and 6 (0.6%) of which were permanent; bilateral palsy was observed in 2 (0.2%) cases. In Group B, 28 (2.8%) injuries were observed, 21 (2.1%) of which were transient and 7 (0.7%) of which were permanent. Differences between the two groups were not statistically significant. ConclusionsOur results show that IONM has a very high sensitivity and negative predictive value, but also good specificity and positive predictive value. For these reasons, in selected patients with LOS, the surgical strategy should be reconsidered. However, patients need to be informed preoperatively about potential strategy changes during the planned bilateral surgery. Future larger and multicenter studies are needed to confirm the benefits of this therapeutic strategy.

Medico-Legal Issues of Intraoperative Neuromonitoring in Thyroid Surgery

Medico-Legal Issues of Intraoperative Neuromonitoring in Thyroid Surgery

Neuromonitorización intraoperatoria en cirugía tiroidea

BackgroundIntraoperative neuromonitoring of the recurrent laryngeal nerve in thyroid surgery facilitates the identification of anatomical structures in cervical endocrine surgery reducing the frequency of vocal cord paralysis. ObjectiveTo study the normal electrophysiological values of the vague and recurrent laryngeal nerves before and after thyroid surgery. To compare rates of injury of recurrent nerve before and after the introduction of the intraoperative neuromonitoring in thyroid surgery. Material and methodsAn observational, descriptive and prospective study in which a total of 490 patients were included. Between 2003-2010, surgery was performed on 411 patients (703 nerves at risk) with systematic identification of recurrent laryngeal nerves. Between 2010-2011 neuromonitorization was also systematically performed on 79 patients. ResultsBefore the introduction of intraoperative neuromonitoring of 704 nerves at risk, there were 14 recurrent laryngeal nerve injuries. Since 2010, after the introduction of the intraoperative neuromonitoring in thyroid surgery, there has been no nerve injury in 135 nerves at risk. ConclusionsWe consider the systematic identification of the recurrent laryngeal nerve is the ‘gold standard’ in thyroid surgery and the intraoperative neuromonitoring of nerves can never replace surgery but can complement it.

Reversal of rocuronium-induced neuromuscular blockade by sugammadex allows for optimization of neural monitoring of the recurrent laryngeal nerve.

The use of neuromuscular blocking agent may effect intraoperative neuromonitoring (IONM) during thyroid surgery. An enhanced neuromuscular-blockade (NMB) recovery protocol was investigated in a porcine model and subsequently clinically applied during human thyroid neural monitoring surgery. Prospective animal and retrospective clinical study. In the animal experiment, 12 piglets were injected with rocuronium 0.6 mg/kg and randomly allocated to receive normal saline, sugammadex 2 mg/kg, or sugammadex 4 mg/kg to compare the recovery of laryngeal electromyography (EMG). In a subsequent clinical application study, 50 patients who underwent thyroidectomy with IONM followed an enhanced NMB recovery protocol-rocuronium 0.6 mg/kg at anesthesia induction and sugammadex 2 mg/kg at the operation start. The train-of-four (TOF) ratio was used for continuous quantitative monitoring of neuromuscular transmission. In our porcine model, it took 49 ± 15, 13.2 ± 5.6, and 4.2 ± 1.5 minutes for the 80% recovery of laryngeal EMG after injection of saline, sugammadex 2 mg/kg, and sugammadex 4 mg/kg, respectively. In subsequent clinical human application, the TOF ratio recovered from 0 to >0.9 within 5 minutes after administration of sugammadex 2 mg/kg at the operation start. All patients had positive and high EMG amplitude at the early stage of the operation, and intubation was without difficulty in 96% of patients. Both porcine modeling and clinical human application demonstrated that sugammadex 2 mg/kg allows effective and rapid restoration of neuromuscular function suppressed by rocuronium. Implementation of this enhanced NMB recovery protocol assures optimal conditions for tracheal intubation as well as IONM in thyroid surgery. NA.