Dosage Effect of Rocuronium on Intraoperative Neuromonitoring in Patients Undergoing Thyroid Surgery

Intraoperative Neurophysiological Monitoring in Neurosurgery

Intraoperative neurophysiological monitoring (IONM) is a crucial advancement in neurosurgery, enhancing procedural safety and precision. This technique involves continuous real-time assessment of neurophysiological signals, aiding surgeons in timely interventions to protect neural structures. In addition to inherent limitations, IONM necessitates a detailed anesthetic plan for accurate signal recording. Given the growing importance of IONM in neurosurgery, we conducted a narrative review including the most relevant studies about the modalities and their application in different fields of neurosurgery. In particular, this review provides insights for all physicians and healthcare professionals unfamiliar with IONM, elucidating commonly used techniques in neurosurgery. In particular, it discusses the roles of IONM in various neurosurgical settings such as tumoral brain resection, neurovascular surgery, epilepsy surgery, spinal surgery, and peripheral nerve surgery. Furthermore, it offers an overview of the anesthesiologic strategies and limitations of techniques essential for the effective implementation of IONM.

A study on the appropriate dose of rocuronium for intraoperative neuromonitoring in Da Vinci robot thyroid surgery: a randomized, double-blind, controlled trial

Background

This study was to explore the effect of different doses of rocuronium bromide on neuromonitoring during Da Vinci robot thyroid surgery.

Methods

This was a prospective, randomized, double-blind, controlled trial that included 189 patients who underwent Da Vinci robot thyroidectomy with intraoperative neuromonitoring(IONM). Patients were randomly divided into three groups and given three different doses of rocuronium (0.3mg/kg, 0.6mg/kg, 0.9mg/kg). Outcome measurements included IONM evoked potential, postoperative Voice Handicap Index-30(VHI-30), intraoperative body movement incidence rate, Cooper score, and hemodynamic changes during anesthesia induction.Results: The difference in IONM evoked potentials at various time points between the three groups was not statistically significant (P>0.05). The difference in Cooper scores and intraoperative body movement incidence rate between 0.6 and 0.9mg/kg groups was statistically significant compared with the 0.3mg/kg group (both P<0.001). There was no statistically significant difference in VHI-30 score and hemodynamic changes during anesthesia induction among the three groups (both P>0.05).

Conclusions

For patients undergoing Da Vinci robot thyroidectomy, a single dose of rocuronium at 0.6 and 0.9mg/kg during anesthesia induction can provide stable IONM evoked potential. Additionally, compared to 0.3 mg/kg, it can offer better tracheal intubation conditions and lower incidence of body movements during surgery. It is worth noting that the use of higher doses of rocuronium should be adjusted based on the duration of IONM and local practices.

Administration of neostigmine after tracheal intubation shortens time to successful intraoperative neuromonitoring during thyroid surgery: a randomized controlled trial

This prospective, randomized controlled trial evaluated the effect of neostigmine for intraoperative neuromonitoring (IONM) during thyroid surgery. Forty subjects undergoing thyroidectomy with IONM, randomized into neostigmine administration after tracheal intubation (Group N, n = 20) or control treatment with normal saline (Group C, n = 20), completed the trial. Electromyography amplitudes of the vagus nerve (V1) were recorded before thyroid dissection. The time from the initial V1 signal check to successful V1 stimulation was recorded. In Group N, all the patients had a successful V1 signal at the first check, whereas ten (50%) patients in Group C had a time delay between the initial V1 check and successful V1 (p < 0.001). The mean delay time among the delayed patients in Group C was 11.2 ± 1.4 min. The mean time from skin incision to successful V1 stimulation was significantly shorter in Group N than in Group C (15.4 ± 2.4 min vs. 19.9 ± 5.7 min, p = 0.003). In Groups N and C, the mean V1 amplitudes were 962.2 ± 434.5 μV vs. 802.3 ± 382.7 μV (p = 0.225), respectively, and the mean R1 amplitudes were 1240.0 ± 836.5 μV vs. 1023.4 ± 455.8 μV (p = 0.316), respectively. There was one bucking event in Group N. In conclusion, neostigmine administration immediately after tracheal intubation can be useful to reverse neuromuscular blockade for successful IONM in thyroid surgeries.

Investigation of potential neuropharmacological activity of neostigmine-glycopyrrolate for intraoperative neural monitoring in thyroid surgery

Intraoperative neuromonitoring (IONM) is frequently used in thyroid surgery to reduce recurrent laryngeal nerve injury. The use of neuromuscular blockade agent to facilitate tracheal intubation, is a common cause of IONM failure. We performed a retrospective analysis to assess the efficacy of neostigmine-glycopyrrolate as a neuromuscular blockade reversal agent for IONM during thyroid surgery. Rocuronium (0.6 mg/kg) was administered for muscle relaxation. Neostigmine (2 mg) and glycopyrrolate (0.4 mg) were administered immediately after intubation. Cricothyroid muscle-twitch response upon external branch of superior laryngeal nerve stimulation and electromyography amplitudes of vagal and recurrent laryngeal nerves before (V1, R1) and after thyroid resection (V2, R2) were recorded. Fifty patients (23 males, 27 females) were included in the analysis. The diagnoses comprised 43 papillary thyroid carcinomas and seven benign diseases. The mean time between rocuronium injection and neostigmine-glycopyrrolate injection was 5.1 ± 1.2 min, and the mean time from neostigmine-glycopyrrolate injection to successful cricothyroid muscle twitching upon external branch of superior laryngeal nerve stimulation was 21.0 ± 4.5 min. All patients had V1 and R1 amplitudes of more than 500 μV each, with mean V1 and R1 amplitudes of 985.3 ± 471.6 μV and 1177.2 ± 572.7 μV, respectively. Neostigmine-glycopyrrolate was effectively used as a neuromuscular blockade reversal agent for IONM in thyroid surgeries without a significant increase in bucking events. Administration of neostigmine-glycopyrrolate immediately after intubation can be recommended for successful NMB reversal to facilitate IONM during thyroid surgery.

Dosage effect of cisatracurium on intubation and intraoperative neuromonitoring during thyroidectomy: a randomized controlled trial

Background

Intraoperative neuromonitoring (IONM) reduces the risk of recurrent laryngeal nerve (RLN) injury during thyroid surgery. However, the use of neuromuscular blocking agents (NMBAs), which are essential to improve intubation conditions, may hinder the electromyographic response during IONM. The aim of this prospective, double-blind, randomized controlled trial was to explore the optimal dosage of cisatracurium to produce adequate muscle relaxation for tracheal intubation without significantly affecting evoked potentials of IONM during thyroidectomy.

Methods

Patients undergoing thyroidectomy with IONM in our institution, with an American Society of Anesthesiologists grade of I-II, aged 18-75 years, and with a body mass index below 32 kg/m² were enrolled and randomly assigned (by random numbers) to receive 1× (group C1) or 2× (group C2) the effective dose (ED₉₅) of cisatracurium for tracheal intubation. The patients, surgeons, and anesthesiologists in charge were blinded to group assignment. Anesthesia was induced with sufentanil, propofol, and cisatracurium (0.05 mg/kgin group C1, 0.1 mg/kg in group C2). Ease of intubation was evaluated with the intubation condition score (Cooper score) and the intubation difficulty scale (IDS). Amplitudes of evoked potentials during intermittent IONM were compared between groups. The primary outcomes were the Cooper score, the IDS score, and the evoked potentials of IONM.

Results

Fifty-three patients were randomized from October 2019 to November 2020, and 52 were analyzed (with 26 patients in each group). The Cooper score was significantly lower in group C1 [median, 8.0 (interquartile range, 7.0-8.3)] than in group C2 [9.0 (9.0-9.0), P<0.001]. The rate of difficult laryngoscopy without external laryngeal pressure was significantly higher in group C1 than in group C2 (61.5% vs. 11.5%, P<0.001). More patients in group C1 required assistance to complete tracheal intubation (16 vs. 4, P=0.001). The IDS score was significantly higher in group C1 [3.0 (0.0-4.0) vs. 1.0 (0.0-1.0), P=0.045]. There were no significant differences between groups in amplitudes of evoked potentials. No serious adverse events were observed.

Conclusions

A dose of 2× ED₉₅ of cisatracurium provided better intubation conditions and easier tracheal intubation than 1× ED₉₅, without disturbing IONM.

Trial Protocol

Chinese Clinical Trial Registry (No. ChiCTR1900022884).

Impact of rocuronium on intraoperative neuromonitoring vagal amplitudes during thyroidectomy

PURPOSE

Neuromuscular blocking agents (NMBA) facilitate endotracheal intubation and reduce related laryngeal morbidity. However, NMBA interfere with intraoperative neuromonitoring amplitudes during thyroidectomy. The goal of this study was to evaluate the impact of rocuronium used for tracheal intubation on early intraoperative neuromonitoring vagal amplitudes observed during first thyroid lobe dissection.

METHODS

This is an observational pharmacoepidemiological study with prospective data collection and retrospective analysis. During the study period, all consecutive patients who underwent thyroid surgery with neuromonitoring were included. Patients underwent endotracheal intubation either using a single dose of rocuronium (NMBA group) or without NMBA (NMBA-free group) according to the anesthesiologist's preference.

RESULTS

Six hundred six patients were included (213 NMBA and 393 NMBA-free group patients). At V1, 39 patients (18%) in the NMBA group had an amplitude < 100 µV (need for curarization reversal in 30 patients) and 13 patients (3.3%) in the NMBA-free group (p < 0.001). In the remaining 554 patients, the mean V1 amplitude was significantly decreased in the NMBA group (544 versus 685 µV; p < 0.001). After exclusion of 25 patients with loss of signal types 1 and 2 during dissection, the difference between mean V1 and mean V2 was significantly lower in NMBA group patients (- 22 versus - 86 µV; p = 0.016).

CONCLUSION

This study provides new data showing how NMBA used for tracheal intubation significantly decrease V1 amplitude baseline and modify amplitude variations from V1 to V2 values during the first thyroid lobe dissection.

LEVEL OF EVIDENCE

Pharmacoepidemiological study.

Low-Dose of Rocuronium During Thyroid Surgery: Effects on Intraoperative Nerve-Monitoring and Intubation

BACKGROUND

Intraoperative Neurophysiological Monitoring (IONM) reduces the incidence of Recurrent Laryngeal Nerve (RLN) injuries during thyroid surgery. To preserve nerve function, long acting neuromuscular blocking agents (NMBA) should be avoided. However, NMBA are necessary for laryngoscopy and endotracheal intubation. We designed this double-blinded, randomized, placebo-controlled trial to assess if a low-dose of rocuronium given at intubation would affect the IONM data recorded before the thyroid dissection.

METHODS

Hundred patients undergoing elective thyroid surgery were randomized to receive either 0.3 mg kg^-1 of low dose rocuronium (intervention) or no-NMBA (control). Intubation was performed with video-laryngoscopy. IONM was placed on RLN and nerve stimulation was performed before and after thyroid dissection. The presence of a valid amplitude prior to dissection was defined when the IONM signal was >100 μV. Occurrence of difficult laryngoscopy was reported together with intubation details including time, difficulty and failure. The lowest peripheral saturation (SpO₂) and the number of desaturation episodes during the intubation were also registered.

RESULTS

No patients showed impaired IONM signal before dissection in both groups. Cormack-Lehane grade was higher in the intervention group (1^1;2) compared to control one (1^1;1; P = 0.046). No-NMBA patients had increased number of difficult laryngoscopies (21% versus 6%, P = 0.041) and intubations (34% versus 8%; P = 0.003) as well as a longer time to intubation (78 [55; 175] versus 55 [31; 110] sec; P = 0.006). Lower values of peripheral SpO₂ during intubation attempt were registered in the no NMBA group (99 [97; 100] versus 99 [99; 100] %; P = 0.020). However, the number of intubation failure was similar between groups (p=0.495).

CONCLUSIONS

Low-dose of rocuronium does not compromise pre-dissection IONM signal and improves intubation condition when compared to a relaxant free strategy.

Randomized Prospective Comparison of Glidescope Video Laryngoscope with Macintosh Laryngoscope in Adult who Underwent Thyroid or Parathyroid Surgery Using Neuromonitorization

Objectives

The present study aims to compare the effects of Glidescope Video Laryngoscope (GVL) and Machintosh Laryngoscope (ML) on the hemodynamic response, intubation time and mucosal damage in adult patients who underwent thyroid or parathyroid surgery using neuromonitorization.

Methods

In this study, 180 patients, aged between 22 and 65 classified as Class I-II in ASA (American Society of Anesthesiologists) and operated under elective conditions were included. Patients were assigned into two groups: Patients intubated with GVL Group G (n=90) and patients intubated with ML Group M (n=90). In both groups, intubation time and the number of trials were recorded. HR (Heart Rate), SpO2 (Peripheral Capillary Oxygen Saturation), SBP (Systolic Blood Pressure), DBP (Diastolic Blood Pressure) and MBP (Mean Blood Pressure) scores were recorded at preinduction, post-induction, post-intubation and three minutes after intubation. Post-operative intubation-associated complications were recorded.

Results

Post intubation HR, DBP and MBP scores were found to be significantly higher in Group M than Group G (p=0,006, p=0.013, p=0.011). Intubation time was found to be significantly higher in Group G than in group M (35.3±10.3, 22.1±7.7 sec). There was no significant difference between the groups' number of trials and intubation-associated complications.

Conclusion

Despite its long intubation time, we believe that GVL may be the first choice laryngoscopy method in the thyroid or parathyroid cases that intubated with a low dose muscle relaxant for neuromonitoring since it has a slight effect than ML on hemodynamism it does not increase mucosal damage and has improved visibility.

Precision Neuromuscular Block Management for Neural Monitoring During Thyroid Surgery

INTRODUCTION

Titration of neuromuscular block (NMB) plays a key role in intraoperative recurrent laryngeal nerve monitoring during thyroid surgery. The combination of neuromuscular blocking agent and timely partial reversal of NMB was investigated in both animal experiments and clinical neuro-monitored thyroidectomy.

METHODS

In animal experiments, 8 piglets received sugammadex to assess the laryngeal EMG recovery after rocuronium-induced NMB. In clinical monitored thyroidectomy, 40 patients each were allocated to conventional group and sugammadex group. Conventional group received rocuronium 0.3 mg/kg at anesthesia induction, while sugammadex group received partial NMB recovery protocol- 0.6 mg/kg of rocuronium at anesthesia induction and 0.5 mg/kg of sugammadex. Main outcome was assessed by first (V1) and final (V2) EMG signal induced by vagal stimulation.

RESULTS

In the porcine model, 50% recovery of laryngeal EMG amplitude was achieved at 16.8 ± 1.9 and 6 ± 2.7 minutes respectively after 0.5 and 1 mg/kg of sugammadex (p < 0.01). In monitored thyroidectomy, EMG amplitudes at V1 in group S and group C were 1214 ± 623 and 915 ± 476 μV, respectively (p = 0.02). Positive and adequately high EMG amplitudes were observed at the early surgical stage for all patients. Sugammadex groups were superior to conventional group in EMG tube placement (p < 0.001).

CONCLUSION

Both porcine model and clinical application showed that precise NMB management by low-dose sugammadex was effective for intraoperative neural monitoring (IONM). The regimen ensured optimal conditions for tracheal intubation and timely neuromuscular function restoration for high-quality EMG signal.

Influence of Sevoflurane-Based Anesthesia versus Total Intravenous Anesthesia on Intraoperative Neuromonitoring during Thyroidectomy

OBJECTIVE

To examine the influence of sevoflurane-based combined intravenous and inhaled anesthesia versus propofol-based total intravenous anesthesia (TIVA) on intraoperative neuromonitoring (IONM) during thyroidectomy.

STUDY DESIGN

A randomized controlled trial.

SETTING

The present study was conducted in a tertiary hospital.

SUBJECTS AND METHODS

Forty patients were randomly assigned to a sevoflurane-based combined intravenous and inhalation group (group S) or a propofol-based total intravenous group (group P). Anesthesia was induced with midazolam, sufentanil, propofol, and cisatracurium in both groups and was maintained with sevoflurane and remifentanil in group S and with TIVA with propofol and remifentanil in group P. IONM was performed intermittently according to the IONM formula standard.

RESULTS

The time until detection of the first positive electromyographic (EMG) signal was significantly longer in group S (median, 41.0 minutes [interquartile range, 37.5-49.3]) than in group P (37.0 minutes [33.3-41.5], P = .028). All patients in group P had a positive EMG signal at initial monitoring, whereas 8 patients (40.0%) in group S did not. The rate of positive EMG signal at initial monitoring was significantly higher in group P than in group S (P = .006). The amplitude of the evoked potentials at V1, R1, R2, and V2 were similar between the groups.

CONCLUSION

Combined intravenous and inhaled anesthesia based on sevoflurane-remifentanil prolonged the time until detection of a positive EMG signal during IONM as compared with TIVA with propofol-remifentanil in patients undergoing thyroidectomy.

Neuromuscular blockade management for intraoperative neural monitoring

This article reviews the literature on development of neuromuscular blockade management in thyroid surgery with intraoperative neural monitoring (IONM) in the past decade. Neuromuscular blockade management includes the choice of neuromuscular blocking agents (NMBAs) and reversal of neuromuscular blockade by sugammadex. A series of animal study and clinical trials showed NMBAs effect on IONM in thyroid surgery. We summarized five NMBA regimens for IONM: (a) relaxant-free regimen, (b) depolarizing NMBA-succinylcholine, (c) titration of nondepolarizing NMBA, and (d) rocuronium combined with sugammadex. The proper management of neuromuscular blockade during IONM has greatly developed over the past decade. The misuse of NMBAs is associated with false IONM interpretations to surgeons. A detailed understanding of NMBAs and neuromuscular blockade management by sugammadex may optimize IONM quality in patients receiving monitored thyroid surgery.

The functional role of the pharyngeal plexus in vocal cord innervation in humans

Classical understanding of the function of the pharyngeal plexus in humans is that it relies on both motor branches for innervation of the majority of pharyngeal muscles and sensory branches for the pharyngeal wall sensation. To date there has been no reported data on the role of the pharyngeal plexus in vocal cord innervation. The aim of this study is to evaluate whether or not the plexus pharyngeus contributes to the innervation of the vocal cords. One hundred twenty-five sides from 79 patients (59 female, 20 male) undergoing thyroid surgery with intraoperative neuromonitoring were prospectively evaluated. While vocal cord function was evaluated with endotracheal tube surface electrodes, cricothyroid and cricopharyngeal muscle electromyographic recordings were obtained with a pair of needle electrodes. The ipsilateral pharyngeal plexus, external branch of the superior laryngeal nerve, and recurrent laryngeal nerve were stimulated with a monopolar probe at 1 mA. With stimulation of the plexus pharyngeus on 125 operated sides, positive electromyographic waveforms were detected from five ipsilateral vocal cords (accounting for 3.2% of all vocal cords monitored and 6.3% of patients). The mean EMG amplitude of the vocal cords with stimulation of the plexus pharyngeus was 147 ± 35.5 μV (range 110-203). In one case, the long latency time of 19.8 ms correlated with innervation by the glottic closure reflex pathway. The short latencies seen in the other four cases [3.9 ± 1.1 ms (range 3.2-5.5)] correlated with direct innervation. In some cases, the plexus pharyngeus may contribute to vocal cord innervation by reflex or direct innervation patterns in humans.

Intraoperative nerve monitoring during thyroid surgery

PURPOSE OF REVIEW

Laryngeal nerve injury, resulting in speech and swallowing dysfunction, is a feared complication of thyroid operations. Routine visualization of the recurrent laryngeal nerve (RLN) has decreased the likelihood of nerve injury, and intraoperative nerve monitoring has been applied in the hope of further enhancing safety.

RECENT FINDINGS

There is conflicting evidence about the value of nerve monitoring during thyroid operations, despite ample research. The data favor nerve monitoring in certain situations, such as neck re-explorations, contralateral RLN injury, extensive or challenging dissections, invasive tumors or large goiters, and nonrecurrent or branching recurrent laryngeal nerves. Continuous intraoperative nerve monitoring may reduce the chances of excessive traction, which is the most common mechanism of injury. Nerve monitoring may also identify and protect the external branches of the superior laryngeal nerve.

SUMMARY

Surgeons should routinely identify recurrent laryngeal nerves during thyroid operations, and intraoperative nerve monitoring might be a useful adjunct to prevent injury. As a result of the relatively low probability of permanent recurrent laryngeal nerve injury, it is difficult to establish the absolute value of nerve monitoring. Further research may focus on continuous nerve monitoring and intraoperative monitoring of the external branches of the superior laryngeal nerves.