Methodological Quality of Systematic Reviews of Intraoperative Neuromonitoring in Thyroidectomy: A Systematic Review.

Importance: Systematic reviews and meta-analyses are considered the best evidence for clinical decision making. Many reviews of intraoperative neuromonitoring (IONM) in thyroidectomy have conflicting results, owing in large part to methodological quality. Objective: To assess the methodological quality and the causes of heterogeneous results of systematic reviews that compare routine IONM vs visual identification of the recurrent laryngeal nerve (RLN) in patients undergoing thyroidectomy. Data Sources: A systematic search was performed of MEDLINE (PubMed), Embase, the Cochrane Library, LILACS (Literatura Latino Americana e do Caribe em Ciências da Saúde), Web of Science, and Google from January 1, 1968, through June 30, 2018. Data were analyzed from July 17 to November 30, 2018. Study Selection: Studies that mentioned performance of a systematic review/meta-analysis during the search period. Data Extraction and Synthesis: Data including study characteristics, type of patients, numbers of nerves at risk, and temporary and definitive RLN paralysis by group were extracted. Data about methodological characteristics, type of statistical analysis and summary estimator, endorsement of systematic review/meta-analysis guidelines, heterogeneity, publication bias, funding, conflict of interest, and statistical analysis were also recorded. The methodological quality was measured with the AMSTAR2 (A Measurement Tool to Assess Systematic Reviews) tool by 2 independent evaluators. Main Outcomes and Measures: Methodological quality. Results: The search identified 13 systematic reviews that included patients who underwent open or minimally invasive thyroidectomy, second operations, and a mixture of low- and high-risk procedures. The mean compliance with the AMSTAR2 overall criteria was 53% (range, 11%-83%); with critical criteria, 71% (range, 50%-94%). The percentage of nerves at risk from RCTs was 4.8%. The mean (SD) crude rate of definitive RLN paralysis was 0.81% (0.22%; median, 0.75% [range, 0.53%-1.30%]) in the monitoring group and 1.14% (0.56%; median, 0.96% [range, 0.57%-2.56%]) in the control group. Conclusions and Relevance: A substantial number of systematic reviews of IONM in thyroidectomy have conflicting results, but their mean methodological quality is critically low. Design of a systematic review should comply with methodological standards and recommendations to offer relevant and practical information for decision making.

[Intraoperative neuromonitoring in thyroid surgery]. / Neuromonitorización intraoperatoria en cirugía tiroidea.

BACKGROUND: Intraoperative neuromonitoring of the recurrent laryngeal nerve in thyroid surgery facilitates the identification of anatomical structures in cervical endocrine surgery reducing the frequency of vocal cord paralysis. OBJECTIVE: To study the normal electrophysiological values of the vague and recurrent laryngeal nerves before and after thyroid surgery. To compare rates of injury of recurrent nerve before and after the introduction of the intraoperative neuromonitoring in thyroid surgery. MATERIAL AND METHODS: An observational, descriptive and prospective study in which a total of 490 patients were included. Between 2003-2010, surgery was performed on 411 patients (703 nerves at risk) with systematic identification of recurrent laryngeal nerves. Between 2010-2011 neuromonitorization was also systematically performed on 79 patients. RESULTS: Before the introduction of intraoperative neuromonitoring of 704 nerves at risk, there were 14 recurrent laryngeal nerve injuries. Since 2010, after the introduction of the intraoperative neuromonitoring in thyroid surgery, there has been no nerve injury in 135 nerves at risk. CONCLUSIONS: We consider the systematic identification of the recurrent laryngeal nerve is the 'gold standard' in thyroid surgery and the intraoperative neuromonitoring of nerves can never replace surgery but can complement it.

Economic analysis of routine neuromonitoring of recurrent laryngeal nerve in total thyroidectomy / Análisis económico de la monitorización neurológica rutinaria del nervio laríngeo recurrente en la tiroidectomía total

Introduction: Thyroidectomy is a common surgery. Routine searching of the recurrent laryngeal nerve is the most important strategy to avoid palsy. Neuromonitoring has been recommended to decrease recurrent laryngeal nerve palsy. Objective: To assess if neuromonitoring of recurrent laryngeal nerve during thyroidectomy is cost-effective in a developing country. Materials and methods: We designed a decision analysis to assess the cost-effectiveness of recurrent laryngeal nerve neuromonitoring. For probabilities, we used data from a meta-analysis. Utility was measured using preference values. We considered direct costs. We conducted a deterministic and a probabilistic analysis. Results: We did not find differences in utility between arms. The frequency of recurrent laryngeal nerve injury was 1% in the neuromonitor group and 1.6% for the standard group. Thyroidectomy without monitoring was the less expensive alternative. The incremental cost-effectiveness ratio was COP$ 9,112,065. Conclusion: Routine neuromonitoring in total thyroidectomy with low risk of recurrent laryngeal nerve injury is neither cost-useful nor cost-effective in the Colombian health system.

Introducción. La tiroidectomía es una cirugía común. La búsqueda rutinaria del nervio laríngeo inferior es la estrategia más importante para evitar la parálisis. Objetivo. Evaluar el costo-efectividad en un país en desarrollo de la monitorización neurológica del nervio laríngeo inferior durante la tiroidectomía. Materiales y métodos. Se diseñó un análisis de decisiones para evaluar el costo-efectividad de la monitorización neurológica del nervio laríngeo inferior. Para las probabilidades se usaron datos de un meta-análisis. La utilidad se determinó con medidas de preferencia. Se incluyeron los costos directos. Se hizo un análisis determinístico y probabilístico. Resultados. No se encontraron diferencias en la utilidad entre las estrategias. La frecuencia de la lesión de este nervio fue de 1 % en el grupo bajo monitorización neurológica y de 1,6 % en el grupo de control. La tiroidectomía sin monitorización fue la alternativa menos costosa. La razón de costo-efectividad incremental fue de COP$ 9.112.065 Conclusión. La monitorización neurológica rutinaria en la tiroidectomía total con bajo riesgo de lesión del nervio laríngeo inferior, no es útil con relación a su costo ni costo-efectiva en el sistema de salud colombiano.

Economic analysis of routine neuromonitoring of recurrent laryngeal nerve in total thyroidectomy.

INTRODUCTION: Thyroidectomy is a common surgery. Routine searching of the recurrent laryngeal nerve is the most important strategy to avoid palsy. Neuromonitoring has been recommended to decrease recurrent laryngeal nerve palsy. OBJECTIVE: To assess if neuromonitoring of recurrent laryngeal nerve during thyroidectomy is cost-effective in a developing country. MATERIALS AND METHODS: We designed a decision analysis to assess the cost-effectiveness of recurrent laryngeal nerve neuromonitoring. For probabilities, we used data from a meta-analysis. Utility was measured using preference values. We considered direct costs. We conducted a deterministic and a probabilistic analysis. RESULTS: We did not find differences in utility between arms. The frequency of recurrent laryngeal nerve injury was 1% in the neuromonitor group and 1.6% for the standard group. Thyroidectomy without monitoring was the less expensive alternative. The incremental cost-effectiveness ratio was COP$ 9,112,065. CONCLUSION: Routine neuromonitoring in total thyroidectomy with low risk of recurrent laryngeal nerve injury is neither cost-useful nor cost-effective in the Colombian health system.

Sexual dimorphism in the human vocal fold innervation.

This study investigated the sexual dimorphism in the recurrent laryngeal nerve (RLN) and thyroarytenoid (TA) muscle, which control the vocal fold. The RLN and TA were bilaterally studied in human specimens obtained from necropsies (seven men and seven women). Analysis of the morphometric parameters showed that the RLN of the men were significantly larger, as shown by the intraperineural area (42.5%) (P=0.006), total number of fibers (38.0%) (P=0.0002), axonal area (34.3%) (P=0.0001), axonal diameter (19.0%) (P=0.0001), and the area of the nerve occupied by myelinated fibers (34.9%) (P=0.001). By contrast, in women, our results showed that the area of the RLN occupied by endoneurial connective tissue was larger (5.7%) (P=0.001). Estimation of the fiber area and shape coefficient showed that the histologic organization of TA is similar in men and women. These results may contribute toward enhancing our understanding about the voice neurobiology.

Recurrent laryngeal nerve: a plexus rather than a nerve?

OBJECTIVES: To analyze the frequency of extralaryngeal branching (ELB) of the recurrent laryngeal nerve (RLN) in a consecutive series of patients undergoing thyroidectomy by the same group of surgeons during an extended period and to compare our findings with the data available in the literature. DESIGN: Retrospective medical record study. SETTING: Academic research. PATIENTS: From March 1, 1983, to September 30, 2008, 2677 patients underwent thyroidectomy. Of these, 1638 patients had surgical information about at least 1 RLN. A total of 1081 patients underwent bilateral operations. During the last 5 years of the study, intraoperative laryngeal nerve monitoring was performed in selected patients using a commercially available system. MAIN OUTCOME MEASURES: Information was obtained regarding 2154 RLNs. RESULTS: A total of 1390 RLNs (64.53%) had ELB. Among 447 patients in whom intraoperative laryngeal nerve monitoring was used, the anterior branches usually exhibited more electrophysiologic activity. CONCLUSIONS: Extralaryngeal branching was found in 64.53% of RLNs in this case series. In recent patients with intraoperative laryngeal nerve monitoring, electrophysiologic activity was observed in the branches, particularly the anteriorly situated ones. Recognition of this frequent anatomical configuration and meticulous preservation of all branches are of paramount importance to decrease postoperative morbidity associated with thyroidectomy.

Vocal fold immobility after thyroidectomy with intraoperative recurrent laryngeal nerve monitoring.

CONTEXT AND OBJECTIVE: Intraoperative nerve monitoring has emerged as a valuable tool to facilitate recurrent laryngeal nerve identification during thyroid surgery, thereby avoiding its injury. The aim was to evaluate vocal fold mobility in patients who underwent thyroidectomy with intraoperative nerve monitoring. DESIGN AND SETTING: Cohort formed by a consecutive series of patients, at a tertiary cancer hospital. METHODS: The subjects were patients who underwent thyroidectomy using intraoperative laryngeal nerve monitoring, between November 2003 and January 2006. Descriptive analysis of the results and comparison with a similar group of patients who did not undergo nerve monitoring were performed. RESULTS: A total of 104 patients were studied. Total thyroidectomy was performed on 65 patients. Vocal fold immobility (total or partial) was detected in 12 patients (6.8% of the nerves at risk) at the first postoperative evaluation. Only six (3.4% of the nerves at risk) continued to present vocal fold immobility three months after surgery. Our previous series with 100 similar patients without intraoperative nerve monitoring revealed that 12 patients (7.5%) presented vocal fold immobility at the early examination, and just 5 (3.1%) maintained this immobility three months after surgery, without significant difference between the two series. CONCLUSION: In this series, the use of intraoperative nerve monitoring did not decrease the rate of vocal fold immobility.

Vocal fold immobility after thyroidectomy with intraoperative recurrent laryngeal nerve monitoring

CONTEXT AND OBJECTIVE: Intraoperative nerve monitoring has emerged as a valuable tool to facilitate recurrent laryngeal nerve identification during thyroid surgery, thereby avoiding its injury. The aim was to evaluate vocal fold mobility in patients who underwent thyroidectomy with intraoperative nerve monitoring. DESIGN AND SETTING: Cohort formed by a consecutive series of patients, at a tertiary cancer hospital. METHODS: The subjects were patients who underwent thyroidectomy using intraoperative laryngeal nerve monitoring, between November 2003 and January 2006. Descriptive analysis of the results and comparison with a similar group of patients who did not undergo nerve monitoring were performed. RESULTS: A total of 104 patients were studied. Total thyroidectomy was performed on 65 patients. Vocal fold immobility (total or partial) was detected in 12 patients (6.8 percent of the nerves at risk) at the first postoperative evaluation. Only six (3.4 percent of the nerves at risk) continued to present vocal fold immobility three months after surgery. Our previous series with 100 similar patients without intraoperative nerve monitoring revealed that 12 patients (7.5 percent) presented vocal fold immobility at the early examination, and just 5 (3.1 percent) maintained this immobility three months after surgery, without significant difference between the two series. CONCLUSION: In this series, the use of intraoperative nerve monitoring did not decrease the rate of vocal fold immobility.

CONTEXTO E OBJETIVO: A monitorização intra-operatória de nervos surgiu como uma ferramenta valiosa para facilitar a identificação do nervo laríngeo recorrente durante a cirurgia de tireóide, evitando a sua lesão. O objetivo foi avaliar a mobilidade das pregas vocais em pacientes submetidos a tireoidectomia com monitorização intra-operatória do nervo laríngeo recorrente. TIPO E LOCAL DO ESTUDO: Coorte de uma série consecutiva de pacientes em um hospital terciário de tratamento de câncer. MÉTODOS: Pacientes foram submetidos à cirurgia de tireóide usando a monitorização intra-operatória do nervo laríngeo recorrente, entre novembro de 2003 e janeiro de 2006. Uma análise descritiva dos resultados e uma comparação com um grupo similar de pacientes que não foram submetidos a monitorização dos nervos foram realizadas. RESULTADOS: Um total de 104 pacientes foi estudado. Tireoidectomia total realizada em 65 pacientes. Imobilidade de pregas vocais (parcial ou total) foi detectada em 12 pacientes (6.8 por cento dos nervos sob risco) na primeira avaliação pós-operatória. Apenas 6 (3.4 por cento dos nervos sob risco) permaneceram com imobilidade de prega vocal três meses após a cirurgia. Nossa série prévia com 100 pacientes similares sem a monitorização intra-operatória revelou que 12 pacientes (7.5 por cento) apresentaram imobilidade de prega vocal na avaliação precoce, e apenas 5 (3.1 por cento) mantiveram a imobilidade três meses após a cirurgia, sem diferença significativa entre as séries. CONCLUSÃO: Nesta série, o uso da monitorização intra-operatória do nervo laríngeo recorrente não diminuiu a taxa de imobilidade de prega vocal.