Recurrent Laryngeal Nerve Monitoring and Rocuronium: A Selective Sugammadex Reversal Protocol

Feasibility of the enhanced neuromuscular blockade recovery protocol with selective use of sugammadex in thyroid surgery with intraoperative neuromonitoring

BACKGROUND

To investigate feasibility of utilizing enhanced neuromuscular blocking agents with selective recovery protocol during thyroid surgery with intraoperative neuromonitoring (IONM).

METHODS

Two-hundred and ninety patients were randomized into two groups: group A 0.3 mg/kg rocuronium and group B 0.6 mg/kg. Sugammadex 2 mg/kg was injected if needed followed initial vagal stimulation (V0). Electromyography signals from vagus and recurrent laryngeal nerves before and after resection were recorded as V1, V2, R1, and R2.

RESULTS

In group B, 30 patients (20.7%) had V0 signals <100 μV, compared to 9 (6.2%) in group A. After sugammadex administration, 144 patients (99.3%) in both groups achieved positive V1 signals. Group B demonstrated a shorter surgical time from rocuronium injection to V2 stimulation compared to group A, accompanied by a significantly lower incidence of intraoperative body movement (0 vs. 16 patients).

CONCLUSIONS

0.6 mg/kg rocuronium with selective use 2 mg/kg sugammadex for IONM in thyroid surgery can meet both anesthesia and surgery demands.

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.

The arousal effect of sugammadex reversal of neuromuscular blockade differs with anesthetic depth in propofol-remifentanil anesthesia: a randomized controlled trial

Sugammadex reverses neuromuscular blockade by encapsulating steroidal neuromuscular blockers; therefore, it does not pharmacologically affect sedation levels. However, some clinicians avoid using it because of sudden unwanted acting out or patient arousal. Previous studies suggested sugammadex-induced awakening, but frontal muscle contraction after sugammadex administration compromised reliability of results obtained from EEG-based anesthesia depth monitoring tools like bispectral index (BIS). We hypothesized that sugammadex would affect patients' arousal depending on their baseline levels of sedation. We evaluated arousal signs after sugammadex administration with BIS between 25 - 35 and 45 - 55 under steady-state propofol-remifentanil anesthesia at the end of a surgery (n = 33 in each group). After sugammadex administration, twelve patients with a BIS of 45 - 55 showed clinical signs of awakening but none with a BIS of 25 - 35 (36.4% vs. 0%, P = 0.001). The distribution of the modified observer's assessment of alertness/sedation scale scores was also significantly different between the two groups (P < 0.001). Changes in the BIS were significantly greater in the BIS 45 - 55 than in the 25 - 35 group (median difference, 7; 95% CI 2 - 19, P = 0.002). Arousal after sugammadex was affected by patient sedation levels, and clinical signs of awakening appeared only in those with BIS 45 - 55. Unwanted arousal of the patient should be considered when using sugammadex under shallow anesthesia.Clinical trial registry number: Clinical Trial Registry of Korea ( https://cris.nih.go.kr ; Principal investigator: Jieae Kim; Registration number: KCT0006248; Date of first registration: 11/06/2021).

Rocuronium with sugammadex as a rescue reversal agent to solve conflicting recommendations for thyroid or parathyroid surgery. A prospective study

INTRODUCTION

For thyroid or parathyroid surgery, there is a challenge to select a muscle relaxant agent allowing a good quality for tracheal intubation without any residual effect at the time of intraoperative neural monitoring.

PATIENTS AND METHODS

In this monocentric study, non-morbidly obese adult patients without risk factors for difficult tracheal intubation who underwent thyroid or parathyroid surgery with intraoperative neural monitoring were prospectively included. After rocuronium injection (0.5 mg.kg^-1) during propofol-sufentanil induction, intubation conditions were evaluated using the Copenhagen score. The surgeon positioned the electrodes NIM® and tested the vagal nerve before recurrent nerve dissection. The signal was considered positive when the wave amplitude exceeded 100 μV. If not, sugammadex (2 mg.kg^-1) was administered. The dissection began when the signal was positive.

RESULTS

From January 2022 to June 2022, 48 out of 50 patients, 39 (81%) female, met inclusion criteria and were prospectively recruited in the study (two patients had predictable difficult intubation criteria). Intubation conditions were clinically acceptable for 46/48 (96%) of patients. The time delay from rocuronium injection to vagal stimulation was 43 min (mean) +/- 11 (SD). The vagal stimulation was positive in 45 patients (94%). In the 3 remaining patients, sugammadex successfully reversed residual curarization and allowed positive vagal stimulation.

DISCUSSION

This prospective study shows that the use of 0.5 mg.kg^-1 rocuronium with sugammadex as a rescue reversal agent allows good quality and safety for intubation conditions and intraoperative neural monitoring in patients scheduled for thyroid or parathyroid surgery.

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.

Optimization of Intraoperative Neural Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery

The application of intraoperative neural monitoring (IONM) has been widely accepted to improve surgical outcomes after thyroid surgery. The malfunction of an IONM system might interfere with surgical procedures. Thus, the development of anesthesia modalities aimed at ensuring functional neuromonitoring is essential. Two key issues should be taken into consideration for anesthetic management. Firstly, most patients undergo recurrent laryngeal nerve monitoring via surface electrodes embedded in an endotracheal tube. Thus, advanced video-assisted devices might optimize surface electrode positioning for improved neuromonitoring signaling accuracy. Secondly, neuromuscular blocking agents are routinely used during thyroid surgery. The ideal neuromuscular block should be deep enough for surgical relaxation at excision and recovered enough for an adequate signal f nerve stimulation. Proper neuromuscular block management could be achieved by titration doses of muscle relaxants and reversal agents.

A Surgeon-Centered Neuromuscular Block Protocol Improving Intraoperative Neuromonitoring Outcome of Thyroid Surgery

BACKGROUND

Neuromuscular blocking agents provide muscular relaxation for tracheal intubation and surgery. However, the degree of neuromuscular block may disturb neuromuscular transmission and lead to weak electromyography during intraoperative neuromonitoring. This study aimed to investigate a surgeon-friendly neuromuscular block degree titrated sugammadex protocol to maintain both intraoperative neuromonitoring quality and surgical relaxation during thyroid surgery.

METHODS

A total of 116 patients were enrolled into two groups and underwent elective thyroid surgery with intraoperative neuromonitoring. All patients followed a standardized intraoperative neuromonitoring protocol with continuous neuromuscular transmission monitoring and received 0.6 mg/kg rocuronium for tracheal intubation. Patients were allocated into two groups according to the degree of neuromuscular block when the anterior surface of the thyroid gland was exposed. The neuromuscular block degree was assessed by the train-of-four (TOF) count and ratio. Patients in group I received sugammadex 0.25 mg/kg for non-deep neuromuscular block degree (TOF count = 1~4). Patients in group II were administered sugammadex 0.5 mg/kg for deep neuromuscular block degree (TOF count = 0). The quality of the intraoperative neuromonitoring was measured using the V₁ electromyography (EMG) amplitude. An amplitude less than 500 μV and greater than 500 μV was defined as weak and satisfactory, respectively.

RESULTS

The quality of the intraoperative neuromonitoring was not different between groups I and II (satisfactory/weak: 75/1 vs. 38/2, P = 0.14). The quality of surgical relaxation was acceptable after sugammadex injection and showed no difference between groups [55/76 (72.3%) in group I vs. 33/40 (82.5%) in group II, P = 0.23].

CONCLUSIONS

This surgeon-centered sugammadex protocol guided by neuromuscular block degree (0.5 mg/kg for deep block and 0.25 mg/kg for others) showed comparably high intraoperative neuromonitoring quality and adequate surgical relaxation. The results expanded the practicality of sugammadex for precise neuromuscular block management during monitored thyroidectomy.

A comparison between cisatracurium and rocuronium-induced neuromuscular block on laryngeal electromyography recovery after neostigmine reversal in a porcine model

BACKGROUND

Inducing and reversing neuromuscular block is essential to a positive outcome of thyroid surgery, with intraoperative neuromonitoring (IONM) being used to decrease recurrent and superior laryngeal nerve injuries and improve vocal outcome. Neostigmine is a non-specific broad-spectrum and inexpensive reversal agent for neuromuscular blocking agents (NMBAs). The aim of this porcine study was to explore the effect of neostigmine on electromyography (EMG) signal recovery profile following the commonly used NMBAs, cisatracurium and rocuronium.

METHODS

Twelve piglets were allocated into two groups with six piglets in each group. When stable baseline EMG signals were obtained, a neuromuscular block was induced by intravenous cisatracurium 0.2 mg/kg (group C) or rocuronium 0.6 mg/kg (group R) for each piglet. We compared laryngeal EMG tracing with spontaneous recovery (control) and neostigmine (0.04 mg/kg) reversal for each group. The time course of real-time laryngeal EMG signals was observed for 30 min from NMBA injection. Effects of neostigmine on EMG signal were assessed at 50% EMG recovery and by the maximum neuromuscular block recovery degree from the baseline value.

RESULTS

Neostigmine shortened the recovery time to 50% EMG amplitude in both group C (16.5 [2.5] vs. 29.0 [2.0] min, P<0.01) and group R (16.5[2.5] vs. 26.5 [1.5] min, P<0.05) compared to spontaneous recovery, respectively. Neostigmine reversal also enhanced the maximum degree of EMG amplitude recovery in both group C (83.6 [5.1] vs. 47.2 [6.1] %, P<0.01) and group R (85.6 [18.2]vs. 57.1 [6.3] %, P<0.05) compared to spontaneous recovery, respectively. The reversal effect of neostigmine did not differ significantly between cisatracurium and rocuronium.

CONCLUSIONS

This porcine model demonstrated that neostigmine provides an adequate and timely IONM signal suppressed by both cisatracurium and rocuronium. These results can potentially expand the options for precision neuromuscular block management during IONM to improve vocal outcomes in thyroid surgery patients.

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.

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.

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

OBJECTIVES/HYPOTHESIS

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.

STUDY DESIGN

Randomized controlled trial.

METHODS

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.

RESULTS

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).

CONCLUSION

A dose of 1 mg/kg sugammadex induced less bucking than 2 m/kg while providing comparable IONM quality during thyroid surgery.

LEVEL OF EVIDENCE

2 Laryngoscope, 131:2154-2159, 2021.

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

BACKGROUND

In 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.

METHODS

Included 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%.

RESULTS

The 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).

CONCLUSION

It 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.

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.

Advantages and pitfalls of clinical application of sugammadex

Sugammadex, a modified γ-cyclodextrin, is one of the drugs focused on in the anesthetic field because it provides rapid and complete reversal from neuromuscular blockade (NMB) by encapsulating rocuronium. Its introduction has revolutionized anesthesia practice because it is a safe, predictable, and reliable neuromuscular antagonist. Hence, its use has increased worldwide. Further, it has been in the spotlight for recovering from deep NMB in laparoscopic surgery and improving the surgical condition. Recently, studies have been conducted on the postoperative outcome after deep NMB and use of sugammadex in various clinical conditions. However, with increase in sugammadex use, reports regarding its complications are increasing. Appropriate dosing of sugammadex with quantitative neuromuscular monitoring is emphasized because under-dosing or over-dosing of sugammadex might be associated with unexperienced complications. Sugammadex is now leaping into an ideal reversal agent, changing the anesthesia practice.

Application of an Intraoperative Neuromonitoring System Using a Surface Pressure Sensor in Parotid Surgery: A Rabbit Model Study

Objectives

Facial nerve monitoring (FNM) can be used to identify the facial nerve, to obtain information regarding its course, and to evaluate its status during parotidectomy. However, there has been disagreement regarding the efficacy of FNM in reducing the incidence of facial nerve palsy during parotid surgery. Therefore, instead of using electromyography (EMG) to identify the location and state of the facial nerve, we applied an intraoperative neuromonitoring (IONM) system using a surface pressure sensor to detect facial muscle twitching. The objective of this study was to investigate the feasibility of using the IONM system with a surface pressure sensor to detect facial muscle twitching during parotidectomy.

Methods

We evaluated the stimulus thresholds for the detection of muscle twitching in the orbicularis oris and orbicularis oculi, as well as the amplitude and latency of EMG and the surface pressure sensor in 13 facial nerves of seven rabbits, using the same stimulus intensity.

Results

The surface pressure sensor detected muscle twitching in the orbicularis oris and orbicularis oculi in response to a stimulation of 0.1 mA in all 13 facial nerves. The stimulus threshold did not differ between the surface pressure sensor and EMG.

Conclusion

The application of IONM using a surface pressure sensor during parotidectomy is noninvasive, reliable, and feasible. Therefore, the IONM system with a surface pressure sensor to measure facial muscle twitching may be an alternative to EMG for verifying the status of the facial nerve.

What is the impact of continuous neuromonitoring on the incidence of injury to the recurrent laryngeal nerve during total thyroidectomy?

BACKGROUND

Continuous intraoperative neuromonitoring may facilitate reversal of intraoperative injurious operative maneuvers in comparison with intermittent intraoperative neuromonitoring. The aim of this study was to evaluate the impact of the routine use of continuous intraoperative neuromonitoring on intraoperative injuries to the recurrent laryngeal nerve.

METHOD

This study was a prospective case series with retrospective analysis of consecutive patients undergoing total thyroidectomy from August 2013 to August 2019. During this period, intermittent intraoperative neuromonitoring (before Mar 2016) and continuous intraoperative neuromonitoring (after Mar 2016) were used in all patients.

RESULTS

We reviewed the outcomes of 603 patients (466 female patients) comprising 236 who underwent intermittent intraoperative neuromonitoring and 367 who underwent continuous intraoperative neuromonitoring. Intraoperative adverse electromyography events (>50% decrease in amplitude between VN1 and VN2) were observed in 87 patients (14.5%) and were less frequent in the continuous intraoperative neuromonitoring group (10.6 vs 20.3%, P = .001). Intraoperative loss of signal (electromyography events with VN2 ≤100μV) were observed in 35 patients (5.8%) without any difference between the 2 groups of patients (5.2 vs 6.8%, P = .415). Postoperative recurrent laryngeal nerve palsies were observed in 36 patients (5.9%) without any difference between the 2 groups of patients (4.9 vs 7.6%, P = .168).

CONCLUSION

The routine use of continuous intraoperative neuromonitoring improves the rate of intraoperative adverse electromyography events but does not impact significantly the rates of loss of signal and recurrent laryngeal nerve palsy.

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

Purpose

The use of nondepolarizing neuromuscular blocking agents (NMBAs) may affect intraoperative neuromonitoring (IONM) during anesthesia used during thyroid and parathyroid surgery.

Methods

The 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.

Results

In 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.

Conclusion

Our 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.

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.

Development of a Novel Intraoperative Neuromonitoring System Using a Surface Pressure Sensor to Detect Muscle Movement: A Rabbit Model Study

OBJECTIVES

False-negative or false-positive responses in intraoperative neuromonitoring (IONM) using electromyography (EMG) in thyroid surgery pose a challenge. Therefore, we developed a novel IONM system that uses a surface pressure sensor instead of EMG to detect muscle twitching. This study aimed to investigate the feasibility and safety of a new IONM system using a piezo-electric surface pressure sensor in an experimental animal model.

METHODS

We developed the surface pressure sensor by modifying a commercial piezo-electric sensor. We evaluated the stimulus thresholds to detect muscle movement, as well as the amplitude and latency of the EMG and surface pressure sensor in six sciatic nerves of three rabbits, according to the stimulus intensity.

RESULTS

The surface pressure sensor detected the muscle movements in response to a 0.1 mA stimulation of all six sciatic nerves. There were no differences in the thresholds of stimulus intensity between the surface pressure sensor and EMG recordings to detect muscle movements.

CONCLUSION

It is possible to measure the change in surface pressure by using a piezo-electric surface pressure sensor instead of EMG to detect muscle movement induced by nerve stimulation. The application of IONM using a piezo-electric surface pressure sensor during surgery is noninvasive, safe, and feasible. Measuring muscle twitching to identify the state of the nerves using the novel IONM system can be an alternative to recording of EMG responses.