The Description of Neuromonitoring for Thyroid Surgery in Kids and Teenagers

Pedro Benyamin^*
*Correspondence: Pedro Benyamin, Department of Neurology, Bern University Hospital, Bern, Switzerland, Email:

Introduction

It is well established that identifying the recurrent laryngeal nerve (RLN) during thyroid surgery is critical. Intraoperative neuromonitoring (IONM) of the RLN has recently been shown to be superior to macroscopic RLN identification without IONM, particularly in high-risk operations such as those for Grave's disease, recurrent goitre, or thyroid carcinomas. There is little data in the literature on the use of IONM in children and adolescents. Concerning thyroid surgery, anatomical and physiological differences between children and adults, such as trachea, larynx, and RLN diameter, point to additional benefits of IONM. This retrospective study compared the utility and potential benefits of IONM in children and adolescents who underwent thyroid surgery in our department with and without it [1].

Description

Corticobulbar motor-evoked potentials (CoMEPs) and continuous electromyography were used to perform IONM (cEMG). CoMEPs were obtained with an electric stimulation (TES) that delivered a stimulus pulse train of 4-7 pulses with a 4 msec interstimulus interval (ISI). The stimulating electrodes were bipolarly positioned at C3, C4, and Cz according to the International 10-20 system. From baseline registration to the end of the surgery, CoMEPs were tested every 15 minutes.mThe RLN was used to collect CoMEPs and cEMG (32-channel system; Cadwell Elite, Kennewick, WA, USA). All patients were sedated and intubated using a Nerve Integrity Monitor (NIM) Standard Reinforced EMG Endotracheal Tube (Medtronic Xomed Inc., Dublin, Ireland; 6.0–8.0 mm I.D.). The impedance of the electrodes was routinely confirmed as 5 k prior to the surgical incision [2].

The gain on the EMG recordings was set to 50-200 mV, the filter to 30-5000 Hz, and the sweep length to 200 msec per division. We examined all children and adolescents who underwent thyroid surgery by the same surgical team between January 2016 and June 2022. Patients' or their parents' informed consent was obtained., The analysed population was divided into two groups: Group A, patients who had surgery between 2016 and 2020 and had the RLN identified without using IONM, and Group B, patients who had surgery during or after 2021, when we began using IONM. The number of RLN lesions in both groups was examined in relation to patient age, underlying thyroid disease, and resection. extent. The IONM was associated with complications such as bleeding into the vocal cords, orotracheal tube cuff damage, and postoperative cervical infections [3].

Despite the fact that bilateral RLNs were clearly identified and preserved in all patients, there was one case of temporary nerve palsy in Group A (8.3%) and one case of nerve dysfunction in Group B (7.7%). A 13.5-year-old boy underwent total thyroidectomy for papillary carcinoma and experienced temporary dysphonia and bitonal voice in the immediate post-operative period, which resolved spontaneously a few hours later. During the follow-up period, no nerve impairment was reported. Group B's patient was a 1.5-year-old boy (the study's youngest patient) with multiple endocrine neoplasia type 2B. In this case, a total thyroidectomy was performed, followed by cEMG activation of the laryngeal musculature and a decrease in CoMEP.

The difference between the beginning and end of the intervention was noted. A pathological examination revealed the presence of medullary microcarcinoma in both thyroid lobes, but no lymph node involvement. The patient developed dysphonia, hoarseness, and wheezing after the procedure; on postoperative day 5, laryngoscopy revealed a hypomobile left vocal cord with glottic insufficiency during phonation. The symptoms had significantly improved at the 1-year follow-up, but laryngoscopy revealed no significant difference.

Thyroid surgery can result in transient or permanent RLN lesions, hypoparathyroidism, postoperative infection, and bleeding. RLN lesions can occur during surgery as a result of transection, clamping, stretching, electro-thermal injury, ligature entrapment, or ischemia. This complication has a reported frequency of 0.5-10% for permanent lesions and 2-28% for temporary lesions in children and adolescents, depending on the underlying thyroid disease and resection extent. The consequences of RLN lesions, such as voice problems and dyspnea (which may necessitate tracheostomy), are feared, particularly in children.Many studies have shown that identifying the RLN during thyroid surgery in adults is critical, especially in cases of thyroid carcinomas, recurrent goitre, Graves' disease, or an abnormal RLN course.Non-identification, malignant pathologies, secondary operations and re-operations for haemorrhage Anatomic variability (e.g., extra-laryngeal branching) or anomaly (e.g., non-RLN), and anatomic distortion from goitre or tumour are risk factors for RLN injury.

Children are more vulnerable to surgically induced injuries than adults because they have a smaller trachea, larynx, vessels, and nerves, anatomical variations of the vascular and nervous course (especially in cases of RLN), the potential presence of the thymus in the caudal cervical compartment, and the pathological thyroid is larger than the normal thyroid.Several methods for detecting the RLN during thyroid surgery have been developed. IONM is a relatively new approach in general practise, particularly in paediatric surgery, with a reported high negative predictive value of 92-100% but a low positive predictive value. Positive predictive value of 10-90% is low and highly variable. Many IONM techniques have been developed for identifying and preserving the RLN during thyroid surgery, but only a few studies on the benefits of IONM in children and adolescents have been published. We used CoMEP from the laryngeal muscles in addition to free-run EMG in the current study.

CoMEP is not commonly used in thyroid surgery, but it has been widely used in cranial nerve IONM in posterior cranial fossa surgery. Our findings showed that the signals generated by these techniques were stable and repeatable, even in difficult anatomical and anaesthetic settings such as paediatrics. There were no IONM-related complications observed, such as postoperative infections, cuff injuries, or hematoma of the cuff. the vocal cords, demonstrating that this procedure is safe for even young patients. Despite the fact that the intergroup differences were not statistically significant, our findings suggest that IONM may aid in the reduction of nerve lesions. The benefit of IONM in children and adolescents was not statistically confirmed due to the small number of patients in our study (due to the rarity of thyroid disease in the paediatric population) and the overall low incidence of complications; however, the incidence of RLN palsy was slightly lower in Group B (7.7%), in which IONM was used, compared to Group A (8.3%).

Furthermore, the patient from Group B with RLN impairment had very unusual clinical characteristics: he was much younger (1.5 years old) than all of the other children in our study (median age: 13 years for Group A and 12.8 years for Group B). years for Group B) and cases reported to date, predisposing him to incidental lesions of microscopic vascular or nervous structures during surgical manoeuvres (by accidental touch or electrocautery). In this patient, there was cEMG activation of the laryngeal musculature and a decrease in CoMEP after the intervention compared to baseline. CoMEPs may serve as a useful predictive index in this patient's medium-term recovery of function. IONM, on the other hand, showed no significant variation during the procedure, implying the need for a new variation of this technique as well as tailor-made tools for younger patients, who are more sensitive to minor changes in pathways and have smaller anatomical features. Furthermore, while IONM is highly sensitive, it is not very specific [4].

This configuration. Various EMG activations from the muscles under investigation were recorded during the procedure, in response to both direct manipulations and indirect solicitation (at risk of injury). To correctly interpret the data in the latter scenarios, the operator should alert the neurophysiologist if he suspects that significant structures are directly involved (rather than waiting for the monitoring to give warning signals). As a result, correct and consistent communication between operators is required to properly use and analyse the signals produced by IONM [5].

Conclusion

Recent evidence from adult thyroid surgery has demonstrated the advantages of IONM in RLN identification and postoperative preservation. We conclude that IONM during thyroid surgery in children and adolescents is of additional benefit due to the low morbidity of IONM, even in the paediatric population. Because thyroid procedures in children and adolescents are uncommon, even in specialised surgical centres, a prospective multicenter study with a large number of patients is required to demonstrate a statistically significant advantage of IONM in this population.

References

1. Chiang, Feng-Yu, Ka-Wo Lee, Hui-Chun Chen and Hsiu-Ya Chen, et al.Standardization of intraoperative neuromonitoring of recurrent laryngeal nerve in thyroid operation. World J Surg 34 (2010): 223-229.

Google Scholar, Crossref, Indexed at

2. Moley, Jeffrey F, Terry C. Lairmore, Gerard M. Doherty and L. Michael Brunt, et al.Preservation of the recurrent laryngeal nerves in thyroid and parathyroid reoperations. Surg 126 (1999): 673-679.

Google Scholar, Crossref, Indexed at

3. Chan, Wai-Fan, Brian Hung-Hin Lang and Chung-Yau Lo.The role of intraoperative neuromonitoring of recurrent laryngeal nerve during thyroidectomy: A comparative study on 1000 nerves at risk. Surg 140 (2006): 866-873.

Google Scholar, Crossref, Indexed at

4. Choi, Sung Yong and Young-Ik Son.Intraoperative neuromonitoring for thyroid surgery: The proven benefits and limitations. Clin Exp Otorhinolaryngol 12 (2019): 335.

Google Scholar, Crossref, Indexed at

5. Kunath, M, J. Hussock, F. Marusch and P. Horschig, et al.Identifying the recurrent laryngeal nerve by intraoperative neuromonitoring. Zentralblatt fur Chir 124 (1999): 641-645.

Google Scholar, Crossref, Indexed at