Seeing Is Not Believing: Intraoperative Nerve Monitoring (IONM) in the Thyroid Surgery

Effect of remimazolam besylate versus propofol on haemodynamic profiles in patients undergoing thyroid surgery with recurrent laryngeal nerve monitoring: a protocol for a randomised controlled trial

INTRODUCTION

Thyroid surgery with intraoperative nerve monitoring under total intravenous anaesthesia often requires deeper sedation due to limitations or lack of neuromuscular blocking agents, usually resulting in haemodynamic instability. Remimazolam, a newly developed sedative, is being studied for its effect on the haemodynamic profile of patients undergoing this procedure and compared with propofol.

METHODS AND ANALYSIS

This will be a single-centre, single-blind, randomised, controlled trial in American Society of Anesthesiologists I-III patients between the ages of 18 and 65 who require recurrent laryngeal nerve monitoring for thyroid surgery. Patients will be randomised 1:1 to either remimazolam besylate or propofol, with 142 cases in each group according to a randomised, computer-generated cohort. The primary outcome is the occurrence of hypotension from induction of anaesthesia to full recovery. Secondary outcomes include the administration of vasoactive agents, the number of hypotension or hypertension episodes, the cumulative duration of hypotension or hypertension, the dose of intraoperative rescue sedation and analgesia, the time to extubation and awakening and the incidence of adverse events.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained from the Medical Ethics Committee of the Affiliated Cancer Hospital and Institute of Guangzhou Medical University (2023-2024). The study protocol was modified according to the reviewers' comments, and the revised version was approved by the Ethics Committee (2024 Research Ethics Amendment No. 3). On completion of the study, we will commit to ensuring that the results are made available to the public, regardless of the outcome. This will include either publication in an appropriate journal or oral presentation at academic conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2300076583.

Impact of Intermittent Intraoperative Neuromonitoring (IONM) on the Learning Curve for Total Thyroidectomy by Residents in General Surgery

INTRODUCTION

Recurrent laryngeal nerve (RNL) identification constitutes the standard in thyroidectomy. Intraoperative nerve monitoring (IONM) has been introduced as a complementary tool for RLN functionality evaluation. The aim of this study is to establish how routine use of IONM can affect the learning curve (LC) in thyroidectomy.

METHODS

Patients undergoing total thyroidectomy performed by surgery residents in their learning curve course in 2 academic hospitals, were divided into 2 groups: Group A, including 150 thyroidectomies performed without IONM by 3 different residents, and Group B, including 150 procedures with routine use of intermittent IONM, by other 3 different residents. LC was measured by comparing operative time (OT), its stabilization during the development of the LC, perioperative complication rate.

RESULTS

As previously demonstrated, the LC was achieved after 30 procedures, in both groups, with no differences due to the use of IONM. Similarly, there were no significant differences among the 2 groups, and between subgroups independently matched, for both OT and complications, even when comparing RLN palsy. Direct nerve visualization and IONM assessment rates were comparable in all groups, and no bilateral RLN palsy (transient or permanent) were reported. No case of interrupted procedure to unilateral lobectomy, due to evidence of RLN injury, was reported.

CONCLUSIONS

The study demonstrates that the use of IONM thyroid surgery, despite requiring a specific training with experienced surgeons, does not particularly affect the learning curve of residents approaching this kind of surgery, and for this reason its routine use should be encouraged even for trainees.

Variant anatomy of non-recurrent laryngeal nerve: when and how should it be taught in surgical residency?

INTRODUCTION

While the performance of a thyroidectomy is generally associated with a low risk of injury to the recurrent laryngeal nerve (RLN), the presence of a non-recurrent nerve (NRLN) increases the risk of this complication. Generally, the intraoperative detection via visual appreciation of variant anatomy of the RLN has been regarded as poor, possibly due to a lack of knowledge of both the normal and aberrant anatomy of the RLN.

MATERIALS AND METHODS

Articles for the review were searched through PubMed using the search terms and their combinations: "non-recurrent laryngeal nerve," "thyroidectomy," "injury," "palsy," "variant anatomy," and "residency," from January 1, 2000, to December 2022. Papers considered for the review were the articles published in English, with additional classic and articles of surgical importance retrieved from the reference list of papers. Only papers relevant to the scope of the review were considered for this review.

FINDINGS

The NRLN has been found to be associated with concurrent vascular abnormalities, such as the presence of an aberrant right subclavian artery (ARSA) or an arteria lusoria originating from the aortic arch. However, it seems that both the normal as well as aberrant anatomy of the RLN is currently not emphasized enough during postgraduate surgical training. With the increased use of intraoperative neuromonitoring (IONM), detection of NRLN has become possible through appropriate neural mapping during thyroid surgery, besides other pointers such as visualization during surgery, computerised tomography, and duplex ultrasound scans to visualize the variant vascular anatomy. There is also a possible role for cadaveric courses, either during medical school or in a post-graduate setting-adapted to the student's level to teach the variant anatomy. With the development of newer techniques such as artificial intelligence, there are potential new options for teaching and training anatomy in the near future.

CONCLUSIONS AND RELEVANCE

Adequate knowledge of the normal and aberrant anatomy of the RLN remains essential for the best outcomes in thyroid surgery, even in the era of the IONM. Moving forward, the knowledge of (aberrant) anatomy should be made an integral part of the core competencies of both medical students and surgical trainees. It is imperative that leaders of the different field work closely together to combine their knowledge towards providing their trainees with the best possible training options.