Continuous neuromonitoring during radiofrequency ablation of benign thyroid nodules provides objective evidence of laryngeal nerve safety

General Principles for the Safe Performance, Training, and Adoption of Ablation Techniques for Benign Thyroid Nodules: An American Thyroid Association Statement

Background: The primary goal of this interdisciplinary consensus statement is to provide a framework for the safe adoption and implementation of ablation technologies for benign thyroid nodules. Summary: This consensus statement is organized around three key themes: (1) safety of ablation techniques and their implementation, (2) optimal skillset criteria for proceduralists performing ablative procedures, and (3) defining expectations of success for this treatment option given its unique risks and benefits. Ablation safety considerations in pre-procedural, peri-procedural, and post-procedural settings are discussed, including clinical factors related to patient selection and counseling, anesthetic and technical considerations to optimize patient safety, peri-procedural risk mitigation strategies, post-procedural complication management, and safe follow-up practices. Prior training, knowledge, and steps that should be considered by any physician who desires to incorporate thyroid nodule ablation into their practice are defined and discussed. Examples of successful clinical practice implementation models of this emerging technology are provided. Conclusions: Thyroid ablative procedures provide valid alternative treatment strategies to conventional surgical management for a subset of patients with symptomatic benign thyroid nodules. Careful patient and nodule selection are critical to the success of these procedures as is extensive pre-procedural patient counseling. Although these emerging technologies hold great promise, they are not without risk and require the development of a unique skillset and environment for optimal, safe performance and consistent outcomes.

Vocal Cord Monitoring by Flexible Fiberoptic Laryngoscopy During Thyroid Radiofrequency Ablation

Introduction: Thermal injury to recurrent laryngeal nerve (RLN) during radiofrequency ablation (RFA) can produce temporary or permanent vocal cord paralysis.1 Hydrodissection with cold 5% glucose of "danger triangle" protects RLN during RFA.2 When RFA is performed under local anesthesia, RLN function is monitored by patients producing vocal sounds.3 Large lesions requiring longer RFAs warrant general sedation where voice cannot be assessed, therefore, an additional technique for RLN protection is advisable. Observation of passive symmetrical vocal cord movements during breathing by laryngeal ultrasonography is useful in assessing vocal cord function4; however, flexible-fiberoptic fibrolaringoscopy (FFL) is gold standard for assessing vocal cord movements,5 anticipating potential RLN damage. We report FFL monitoring during RFA under general sedation on a large thyroid nodule. FFL during RFA may detect RLN irritation and dysfunction if asymmetry in passive vocal cord movements is noted. Should asymmetry appear, RFA operator stops delivering energy and repositions electrode needle. Materials and Methods: Thyroid function tests, blood glucose, creatinine, transaminase, International-Normalized-Ratio, and electrocardiogram were performed. Operating room (OR) layout created sufficient space for ear-nose-throat (ENT) and RFA operators. An examination with a fiberscope camera demonstrated normal vocal cord adduction during phonation and abduction during breathing. The procedure was assisted by an anesthetist administering fentanyl 50 mcg, midazolam 1.5 to 5.0 mg, and propofol infusion 2 mg/(kg·h). General sedation was conducted so that reflexes were attenuated but still observable. Incorporating in OR by an anesthetist who performs general sedation reduces side effects and complications.6 Ultrasonography showed a 34-mL right lobe nodule abutting on the RLN area. After sedation with propofol, the ENT specialist inserted an endoscope until the glottic plane. During calm breathing, vocal cords moved symmetrically. After obtaining anterior nodule hydrodissection from strap and sternocleidomastoid muscles with 10 mL of 2% lidocaine, posterior hydrodissection was achieved by ultrasound-guided administration of 30 mL of 5% cold glucose. Anterior and posterior hydrodissections merged, separating nodule from neck structures. The radiofrequency electrode needle was then inserted into the nodule, initially positioned in inferior nodule portion adjacent to danger triangle previously isolated by hydrodissection. Initial power was 30 watts. Moving-shot technique was used. Results: FFL was performed throughout thyroid RFA. Symmetric vocal cord movements during breathing demonstrated no RLN irritation. FFL monitoring allowed observation of natural reflexive phenomena, including swallowing. Complete nodule ablation was achieved. FFL performed post-RFA confirmed normal vocal cord motility. Conclusions: We report the first-time use of FFL for vocal cord monitoring during RFA. FFL was easily performed by the ENT specialist and well tolerated by the patient. Avoiding danger triangle and precise RFA needle positioning is key in preventing RLN injury. Benign nodules regrow if total ablation is not achieved7 and some authors propose additional procedures to complete ablation8 that obviously incurs costs. Total RFA nodule ablation-assisted FFL monitoring eliminates the need for repetitive RFAs, thus reducing overall treatment costs. Finally, FFL monitoring does not prolong procedure, as it is performed simultaneously with RFA. FFL is a valid technique when used in conjunction with hydrodissection to further prevent RLN thermal injury during RFA, especially indicated for large thyroid nodule ablation and professional voice users. Patient Consent and Permission: The patient provided written consent for FFL monitoring and permission to use his portrayals and ultrasonographic images during RFA. The study was completed in accordance with the Declaration of Helsinki as revised in 2013. Adherence to institutional review board protocols was granted. Disclaimer: Representation of any instrumentation within the video does not indicate any endorsement of the product and/or company by the publisher, the American Thyroid Association, or the authors. No competing financial interests exist. Runtime of video: 9 mins 39 secs.

EDB-FN targeted probes for the surgical navigation, radionuclide imaging, and therapy of thyroid cancer

PURPOSE

Extradomain B of fibronectin (EDB-FN) is a promising diagnostic and therapeutic biomarker for thyroid cancer (TC). Here, we identified a high-affinity EDB-FN targeted peptide named EDBp (AVRTSAD) and developed three EDBp-based probes, Cy5-PEG4-EDBp(Cy5-EDBp), [18F]-NOTA-PEG4-EDBp([18F]-EDBp), and [177Lu]-DOTA-PEG4-EDBp ([177Lu]-EDBp), for the surgical navigation, radionuclide imaging, and therapy of TC.

METHODS

Based on the previously identified EDB-FN targeted peptide ZD2, the optimized EDB-FN targeted peptide EDBp was identified by using the alanine scan strategy. Three EDBp-based probes, Cy5-EDBp, [18F]-EDBp, and [177Lu]-EDBp, were developed for fluorescence imaging, positron emission tomography (PET) imaging, and radiotherapy in TC tumor-bearing mice, respectively. Additionally, [18F]-EDBp was evaluated in two TC patients.

RESULTS

The binding affinity of EDBp to the EDB fragment protein (Kd = 14.4 ± 1.4 nM, n = 3) was approximately 336-fold greater than that of the ZD2 (Kd = 4839.7 ± 361.7 nM, n = 3). Fluorescence imaging with Cy5-EDBp facilitated the complete removal of TC tumors. [18F]-EDBp PET imaging clearly delineated TC tumors, with high tumor uptake (16.43 ± 1.008%ID/g, n = 6, at 1-h postinjection). Radiotherapy with [177Lu]-EDBp inhibited tumor growth and prolonged survival in TC tumor-bearing mice (survival time of different treatment groups: saline vs. EDBp vs. ABRAXANE vs. [177Lu]-EDBp = 8.00 d vs. 8.00 d vs. 11.67 d vs. 22.33 d, ***p < 0.001). Importantly, the first-in-human evaluation of [18F]-EDBp demonstrated that it had specific targeting properties (SUVmax value of 3.6) and safety.

CONCLUSION

Cy5-EDBp, [18F]-EDBp, and [177Lu]-EDBp are promising candidates for the surgical navigation, radionuclide imaging, and radionuclide therapy of TC, respectively.

Improving Voice Outcomes after Thyroid Surgery and Ultrasound-Guided Ablation Procedures

The field of endocrine surgery has expanded from the traditional open neck approach to include remote access techniques as well as minimally invasive approaches for benign and malignant thyroid nodules. In experienced hands and with careful patient selection, each approach is considered safe, however complications can and do exist. Post-operative dysphonia can have serious consequences to the patient by affecting quality of life and ability to function at work and in daily life. Given the significance of post-procedural dysphonia, we review the surgical and non-surgical techniques for minimizing and treating recurrent laryngeal nerve injury that can be utilized with the traditional open neck approach, remote access thyroidectomy, or minimally invasive thermal ablation.

Intraoperative Neuromonitoring: Evaluating the Role of Continuous IONM and IONM Techniques for Emerging Surgical and Percutaneous Procedures

Intraoperative nerve monitoring (IONM) is a tool used during thyroid surgery to assist in the identification of the recurrent laryngeal nerve (RLN). Multiple IONM systems that exist for thyroidectomy require intubation with an endotracheal tube. Given that one of the advantages of thermal ablation procedures, such as radiofrequency ablation, is that they can be done safely without the use of general anesthesia, nerve monitoring systems that utilize cutaneous surface electrodes have been developed, though are not widely available in the United States. This article will review the use of IONM for RFA including the cutaneous surface electrode system.

Intraoperative Neuromonitoring: Evaluating the Role of Continuous IONM and IONM Techniques for Emerging Surgical and Percutaneous Procedures

Continuous and intermittent intraoperative nerve monitoring (IONM) has become an important asset for endocrine surgeons over the past few decades. The ability to determine neurophysiologic integrity of the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) on top of identification and meticulous dissection of the nerve in the surgical field, has allowed for advances in technology and improved outcomes when it comes to prevention of vocal fold immobility. This article aims to compare in review continuous and intermittent nerve monitoring (CIONM, IIONM), as well as review the current paradigms of their use. This article will also discuss the future of intraoperative nerve monitoring technologies in scarless thyroid surgery and percutaneous approaches to thyroid pathology in form of radiofrequency ablation (RFA).

Clarifying optimal outcome measures in intermittent and continuous laryngeal neuromonitoring

BACKGROUND

Intraoperative neuromonitoring (IONM) techniques have evolved over the past decade into intermittent IONM (I-IONM) and continuous IONM (C-IONM) modes of application. Despite many prior publications on both types of IONM, there remains uncertainty about what outcomes should be measured for each form of IONM. The primary objective of this paper is to define categories of benefit for I-IONM/C-IONM and to clarify and standardize their reporting outcomes.

METHODS

Expert review consensus statement utilizing modified Delphi methodology.

RESULTS

I-IONM provides diagnosis, classification, and prevention of nerve injury through accurate and early nerve identification. C-IONM provides real-time information on nerve functional integrity and thus may prevent some types of nerve injury but cannot assist in nerve localization. Sudden mechanisms of nerve injury cannot be predicted or prevented by either technique.

CONCLUSIONS

I-IONM and C-IONM are complementary techniques. Future studies evaluating the utility of IONM should focus on outcomes that are appropriate to the type of IONM being utilized.