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Journal ArticleDOI

Electrophysiological neural monitoring of the laryngeal nerves in thyroid surgery: review of the current literature.

05 Jun 2015-Gland surgery (AME Publications)-Vol. 4, Iss: 5, pp 368-375
TL;DR: The article will discuss the value of continuous IONM (C-IOMN) that may prevent nerve injury by detecting EMG waveform changes indicating impending nerve injury.
Abstract: Recurrent laryngeal nerve (RLN) injury is one of the most common complications of thyroid surgery. RLN injury can cause vocal cord paralysis, affecting the patient's voice and the quality of life. Injury of the external branch of the superior laryngeal nerve (EBSLN) can cause cricothyroid muscle denervation affecting high vocal tones. Thus, securing the laryngeal nerves in these surgeries is of utmost importance. Visual identification of the nerves has long been the standard method for this precaution. Intraoperative neuromonitoring (IONM) has been introduced as a novel technology to improve the protection of the laryngeal nerves and reduce the rate of RLN injury. The aim of this article is to provide a brief description of the technique and review the literature to illustrate the value of IONM. IONM can provide early identification of anatomical variations and unusual nerve routes, which carry a higher risk of injury if not detected. IONM helps in prognosticating postoperative nerve function. Moreover, by detecting nerve injury intraoperatively, it aids in staging bilateral surgeries to avoid bilateral vocal cord paralysis and tracheostomy. The article will discuss the value of continuous IONM (C-IOMN) that may prevent nerve injury by detecting EMG waveform changes indicating impending nerve injury. Herein, we are also discussing anatomy of laryngeal nerves and aspects of its injury.
Citations
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Journal ArticleDOI
TL;DR: There was no firm evidence of an advantage or disadvantage comparing IONM with visual nerve identification only for permanent RILN palsy, and the evidence reported in this review was mostly of very low certainty.
Abstract: Background Injuries to the recurrent inferior laryngeal nerve (RILN) remain one of the major post-operative complications after thyroid and parathyroid surgery. Damage to this nerve can result in a temporary or permanent palsy, which is associated with vocal cord paresis or paralysis. Visual identification of the RILN is a common procedure to prevent nerve injury during thyroid and parathyroid surgery. Recently, intraoperative neuromonitoring (IONM) has been introduced in order to facilitate the localisation of the nerves and to prevent their injury during surgery. IONM permits nerve identification using an electrode, where, in order to measure the nerve response, the electric field is converted to an acoustic signal. Objectives To assess the effects of IONM versus visual nerve identification for the prevention of RILN injury in adults undergoing thyroid surgery. Search methods We searched CENTRAL, MEDLINE, Embase, ICTRP Search Portal and ClinicalTrials.gov. The date of the last search of all databases was 21 August 2018. We did not apply any language restrictions. Selection criteria We included randomised controlled trials (RCTs) comparing IONM nerve identification plus visual nerve identification versus visual nerve identification alone for prevention of RILN injury in adults undergoing thyroid surgery DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts for relevance. One review author carried out screening for inclusion, data extraction and 'Risk of bias' assessment and a second review author checked them. For dichotomous outcomes, we calculated risk ratios (RRs) with 95% confidence intervals (CIs). For continuous outcomes, we calculated mean differences (MDs) with 95% CIs. We assessed trials for certainty of the evidence using the GRADE instrument. Main results Five RCTs with 1558 participants (781 participants were randomly assigned to IONM and 777 to visual nerve identification only) met the inclusion criteria; two trials were performed in Poland and one trial each was performed in China, Korea and Turkey. Inclusion and exclusion criteria differed among trials: previous thyroid or parathyroid surgery was an exclusion criterion in three trials. In contrast, this was a specific inclusion criterion in another trial. Three trials had central neck compartment dissection or lateral neck dissection and Graves' disease as exclusion criteria. The mean duration of follow-up ranged from 6 to 12 months. The mean age of participants ranged between 41.7 years and 51.9 years.There was no firm evidence of an advantage or disadvantage comparing IONM with visual nerve identification only for permanent RILN palsy (RR 0.77, 95% CI 0.33 to 1.77; P = 0.54; 4 trials; 2895 nerves at risk; very low-certainty evidence) or transient RILN palsy (RR 0.62, 95% CI 0.35 to 1.08; P = 0.09; 4 trials; 2895 nerves at risk; very low-certainty evidence). None of the trials reported health-related quality of life. Transient hypoparathyroidism as an adverse event was not substantially different between intervention and comparator groups (RR 1.25; 95% CI 0.45 to 3.47; P = 0.66; 2 trials; 286 participants; very low-certainty evidence). Operative time was comparable between IONM and visual nerve monitoring alone (MD 5.5 minutes, 95% CI -0.7 to 11.8; P = 0.08; 3 trials; 1251 participants; very low-certainty evidence). Three of five included trials provided data on all-cause mortality: no deaths were reported. None of the trials reported socioeconomic effects. The evidence reported in this review was mostly of very low certainty, particularly because of risk of bias, a high degree of imprecision due to wide confidence intervals and substantial between-study heterogeneity. Authors' conclusions Results from this systematic review and meta-analysis indicate that there is currently no conclusive evidence for the superiority or inferiority of IONM over visual nerve identification only on any of the outcomes measured. Well-designed, executed, analysed and reported RCTs with a larger number of participants and longer follow-up, employing the latest IONM technology and applying new surgical techniques are needed.

79 citations

Journal ArticleDOI
TL;DR: CIONM overcomes the key methodological limitation inherent in intermittent nerve monitoring (IINOM); which is allowing the nerve to be at risk in between the stimulations.
Abstract: The continuous intraoperative neural monitoring (CIONM) technique is increasingly acknowledged as a useful tool to recognize impending nerve injury and to abort the related manoeuvre to prevent nerve injury during thyroid surgery. CIONM provides valuable real-time information constantly, which is really useful during complex thyroid surgeries especially in the settings of unusual anatomy. Thus, CIONM overcomes the key methodological limitation inherent in intermittent nerve monitoring (IINOM); which is allowing the nerve to be at risk in between the stimulations. The clinically important combined electromyographic (EMG) event, indicative of impending recurrent laryngeal nerve (RLN) injury, prevents the majority of traction related injuries to the anatomically intact RLN enabling modification of the causative surgical manoeuvre in 80% of cases. These EMG changes can progress to loss of EMG signal with postoperative vocal cord palsy (VCP) if corrective action is not taken. As a further extension, CIONM also helps to identify intraoperative functional nerve recovery with restitution of amplitude to ≥50% of initial baseline; this allows continuing of resection of contralateral side. CIONM facilitates for early corrective action before permanent damage to the nerve has been done. CIONM is a recent but rapidly evolving technique, constantly being refined by various studies focusing on improvement in its implementation and interpretation, as well as on the elimination of the technical snags.

65 citations

Journal ArticleDOI
TL;DR: The results show that IONM has a very high sensitivity and negative predictive value, but also good specificity and positive predictive value and in selected patients with LOS, the surgical strategy should be reconsidered.

48 citations

Journal ArticleDOI
TL;DR: This review summarizes the current key achievements of IONM; outlines opportunities for improvement regarding clinical implementation; and suggests areas of future research in this rapidly evolving field of intraoperative neuromonitoring.
Abstract: The number of thyroid operations and there radically continues to rise in the western hemisphere, bringing prevention of recurrent laryngeal nerve (RLN) palsy to the fore. Overall, the incidence of RLN palsy is fairly low but continues to prompt litigation for malpractice. In an effort to diminish transient, and more importantly permanent, RLN palsy rates, intraoperative neuromonitoring (IONM) has been advocated as a risk minimization tool. Recent meta-analyses of studies, many of which were limited by poor study design and the sole use of intermittent nerve stimulation, were unable to demonstrate superiority of IONM over mere anatomic RLN dissection. This is where continuous IONM (CIONM) comes into play: this technology enables the surgeon to (I) identify impending nerve injury as it unfolds; (II) release distressed nerves by reversing causative surgical maneuvers; and (III) verify functional nerve recovery after intraoperative loss of the electromyographic signal. Despite this superiority, CIONM is not devoid of methodological limitations, which need to be accounted for. This review summarizes the current key achievements of IONM; outlines opportunities for improvement regarding clinical implementation; and suggests areas of future research in this rapidly evolving field.

44 citations

Journal ArticleDOI
TL;DR: The advent of continuous vagus stimulation (CVS), eliminating lag time between nerve preparation with potential trauma and stimulation, has transformed the intraoperative surgical strategy in thyroid surgery, delineating the extent to which CVS has changed the landscape.

15 citations

References
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Journal ArticleDOI
TL;DR: A review of the literature and cumulative experience of the multidisciplinary International Neural Monitoring Study Group with IONM spanning nearly 15 years confirms there is little uniformity in application of and results from nerve monitoring across different centers and helps identify areas where additional research is necessary.
Abstract: Intraoperative neural monitoring (IONM) during thyroid and parathyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual nerve identification. Despite the increasing use of IONM, review of the literature and clinical experience confirms there is little uniformity in application of and results from nerve monitoring across different centers. We provide a review of the literature and cumulative experience of the multidisciplinary International Neural Monitoring Study Group with IONM spanning nearly 15 years. The study group focused its initial work on formulation of standards in IONM as it relates to important areas: 1) standards of equipment setup/endotracheal tube placement and 2) standards of loss of signal evaluation/intraoperative problem-solving algorithm. The use of standardized methods and reporting will provide greater uniformity in application of IONM. In addition, this report clarifies the limitations of IONM and helps identify areas where additional research is necessary. This guideline is, at its forefront, quality driven; it is intended to improve the quality of neural monitoring, to translate the best available evidence into clinical practice to promote best practices. We hope this work will minimize inappropriate variations in monitoring rather than to dictate practice options.

815 citations


"Electrophysiological neural monitor..." refers background or methods in this paper

  • ...The German Association of Endocrine Surgeons practice guidelines and the International Neural Monitoring Study Group guidelines both support using IONM in all thyroid surgeries (23,34), while the American Head and Neck Society endorses its utilization in thyroid cancer cases, particularly patients with RLN palsy....

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  • ...The International Neural Monitoring Study Group classified nerve injury into two categories: segmental, which involves a lesion to a clear-cut segment of the RLN, and global, where all the RLN and vagus are nonconductive which may indicate an intralaryngeal focus of injury (23)....

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  • ...Prolonged latency time can be used in combination with decreased amplitude or complete LOS as an indicator of nerve injury (23,40)....

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  • ...Due to its safety and simplicity, it is superior to other modalities as glottic observation, laryngeal palpation, postcricoid surface electrodes and intramuscular electrodes (23)....

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  • ...Furthermore, it can detect the most proximal RLN or EBSLN injuries (23)....

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Journal ArticleDOI
01 Dec 2004-Surgery
TL;DR: Visual nerve identification was identified to be the gold standard of RLN treatment in thyroid surgery because of the overall low frequency of RLNP and no statistical difference compared with visual nerve identification only was reached in the setting of this study.

592 citations


"Electrophysiological neural monitor..." refers background in this paper

  • ...IONM can diagnose nonRLN which has shorter latency time compared to the recurrent nerve (11)....

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  • ...It was reported that IONM can reduce the rate of transient RLN injury in thyroid surgery (11,28,29)....

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  • ...Intraoperative visual identification has been the gold standard for securing the laryngeal nerves during thyroid surgery (10-12)....

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  • ...reported that running a statistically powerful study would require millions of patients (11)....

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Journal ArticleDOI
TL;DR: The aim of this study was to test the hypothesis that identification of the recurrent laryngeal nerve during thyroid surgery reduces injury and that intraoperative nerve monitoring may be of additional benefit.
Abstract: Background: The aim of this study was to test the hypothesis that identification of the recurrent laryngeal nerve (RLN) during thyroid surgery reduces injury, and that intraoperative nerve monitoring may be of additional benefit. Methods: One thousand consenting patients scheduled to have bilateral thyroid surgery were randomized to standard protection or additional nerve monitoring. The primary outcome measure was prevalence of RLN injury. Results: Of 1000 nerves at risk in each group, transient and permanent RLN injuries were found respectively in 38 and 12 nerves without RLN monitoring (P = 0·011) and 19 and eight nerves with RLN monitoring (P = 0·368). The prevalence of transient RLN paresis was lower in patients who had RLN monitoring by 2·9 per cent in high-risk patients (P = 0·011) and 0·9 per cent in low-risk patients (P = 0·249). The negative and positive predictive values of RLN monitoring in predicting postoperative vocal cord function were 98·9 and 37-8 per cent respectively. Conclusion: Nerve monitoring decreased the incidence of transient but not permanent RLN paresis compared with visualization alone, particularly in high-risk patients. Registration number: NCT00661024 (http://www.clinicaltrials.gov).

376 citations

Journal ArticleDOI
TL;DR: This clinical practice guideline provides evidence-based recommendations for management of the patient’s voice when undergoing thyroid surgery during the preoperative, intraoperative, and postoperative period.
Abstract: ObjectiveThyroidectomy may be performed for clinical indications that include malignancy, benign nodules or cysts, suspicious findings on fine needle aspiration biopsy, dysphagia from cervical esop...

322 citations

Journal ArticleDOI
27 Aug 2012-Thyroid
TL;DR: The increased rates of transient and permanent hypoparathyroidism in the series suggest a critical review of indications for the routine use of prophylactic CND for PTC and suggests that ipsilateral CND ipsilaterally to the tumor associated with total thyroidectomy may represent an effective strategy for reducing the rate of permanent Hypoparathiroidism.
Abstract: Background: Prophylactic central neck dissection (CND) has been proposed in the treatment of patients affected by papillary thyroid carcinoma (PTC) with clinically negative neck lymph nodes The procedure allows pathologic staging of lymph nodes of the central compartment and treatment of the micrometastases Nevertheless, the morbidity that its routine use adds to the total thyroidectomy must be taken into account The aim of this study was to characterize the morbidity that CND adds to the total thyroidectomy Methods: This was a retrospective study of 1087 patients with PTC and clinically negative neck lymph nodes Patients were divided into three study groups: Group A, total thyroidectomy; Group B, total thyroidectomy and ipsilateral CND; Group C, total thyroidectomy and bilateral CND Primary endpoints of the study were evaluated by comparing the rates of transient and permanent recurrent laryngeal nerve (RLN) injury and hypoparathyroidism in the three study groups Results: Analysis of data showed n

321 citations


Additional excerpts

  • ...In bilateral surgery, when nerve injury is detected by IONM on the initial side, the procedure could be staged by postponing operation on the other side until vocal cord function can be verified (41,42)....

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