The utility of intraoperative nerve monitoring during thyroid surgery

Frequency of side effects experienced in two different NIM-EMG tubes used in thyroid and parathyroid surgery; a prospective observational study

BACKGROUND

In this study, we observed the frequency of side effects encountered when the neural integrity monitor electromyogram endotracheal tube (NIM-EMG-ETT) was used in thyroidectomy and parathyroidectomy surgeries.

METHODS

After obtaining hospital ethics committee approval, 239 cases affiliated with the American Society of Anesthesiologists (ASA II-IV) who used NIM EMG tubes in thyroid and parathyroid surgery were included in the prospective observational study. Tube and patient-related complications encountered with two different NIM EMG-ETT (silicone and polyvinyl chloride-PVC) were recorded.

RESULTS

The average age of the patients is 49.50 ± 13.44 years, the average BMI is 28.25 ± 4.91 kg/m2, the median surgery time is 115 (32-475) minutes, 75.7% are women, 97.5% are ASA II. Additional diseases other than thyroid and parathyroid problems were present in 77.3%. Thyroidectomy was performed in 73.2% of the patients. In our study, only 0.8% of patients with transient recurrent laryngeal nerve RLN paralysis were observed in thyroid and parathyroid surgeries performed using NIM-EMG tubes, 3 patient already had nerve involvement in the preoperative period. The most common complication was loss of stimulation response related to tubes and patient-related ventilation failure. There was no difference between the complications of silicone and PVC tubes except for irregular EMG response.

CONCLUSIONS

There was no significant difference in side effects other than irregular EMG response in the two different tubes we used in our study. It was observed that prolonging the surgical time increased the risk of irregular EMG response. It should not be forgotten that no matter which NIM-EMG tube is used, additional risks are encountered during the intubation and extubation process. In order to avoid negative consequences, it is necessary to follow the usage rules recommended by the manufacturer when using NIM-EMG tubes.

Effects on Voice Quality of Thyroidectomy: A Qualitative and Quantitative Study Using Voice Maps

OBJECTIVES

This study aims to explore the effects of thyroidectomy-a surgical intervention involving the removal of the thyroid gland-on voice quality, as represented by acoustic and electroglottographic measures. Given the thyroid gland's proximity to the inferior and superior laryngeal nerves, thyroidectomy carries a potential risk of affecting vocal function. While earlier studies have documented effects on the voice range, few studies have looked at voice quality after thyroidectomy. Since voice quality effects could manifest in many ways, that a priori are unknown, we wish to apply an exploratory approach that collects many data points from several metrics.

METHODS

A voice-mapping analysis paradigm was applied retrospectively on a corpus of spoken and sung sentences produced by patients who had thyroid surgery. Voice quality changes were assessed objectively for 57 patients prior to surgery and 2months after surgery, by making comparative voice maps, pre- and post-intervention, of six acoustic and electroglottographic (EGG) metrics.

RESULTS

After thyroidectomy, statistically significant changes consistent with a worsening of voice quality were observed in most metrics. For all individual metrics, however, the effect sizes were too small to be clinically relevant. Statistical clustering of the metrics helped to clarify the nature of these changes. While partial thyroidectomy demonstrated greater uniformity than did total thyroidectomy, the type of perioperative damage had no discernible impact on voice quality.

CONCLUSIONS

Changes in voice quality after thyroidectomy were related mostly to increased phonatory instability in both the acoustic and EGG metrics. Clustered voice metrics exhibited a higher correlation to voice complaints than did individual voice metrics.

Does the Use of Intraoperative Neuromonitoring during Thyroid and Parathyroid Surgery Reduce the Incidence of Recurrent Laryngeal Nerve Injuries? A Systematic Review and Meta-Analysis

Injury to the recurrent laryngeal nerve (RLN) can be a devastating complication of thyroid and parathyroid surgery. Intraoperative neuromonitoring (IONM) has been proposed as a method to reduce the number of RLN injuries but the data are inconsistent. We performed a meta-analysis to critically assess the data. After applying inclusion and exclusion criteria, 60 studies, including five randomized trials and eight non-randomized prospective trials, were included. A meta-analysis of all studies demonstrated an odds ratio (OR) of 0.66 (95% CI [0.56, 0.79], p < 0.00001) favoring IONM compared to the visual identification of the RLN in limiting permanent RLN injuries. A meta-analysis of studies employing contemporaneous controls and routine postoperative laryngoscopy to diagnose RLN injuries (considered to be the most reliable design) demonstrated an OR of 0.69 (95% CI [0.56, 0.84], p = 0.0003), favoring IONM. Strong consideration should be given to employing IONM when performing thyroid and parathyroid surgery.

Comparing Thyroidectomy Techniques, Surgical Loupe and Neuromonitoring Between ENT and Endocrine Surgeons-an Observational Study

Thyroid surgery is performed by ENT head and neck (ENT-HNS), endocrine (ES) and general surgeons (GS). Each modality adopts different surgical techniques causing difference in outcome, operative time and postoperative complication. A retrospective chart review of thyroid surgeries performed by two ENT-HNS, three ES of a single tertiary center was conducted. We compared the use of neuromonitoring and surgical loupe and subsequent patient outcomes between surgeries performed by ENT-HNS versus ES, focusing on parathyroid gland identification, operative duration, vocal cord paralysis and length of hospital stay. A total of 167 patients underwent thyroid surgery. Surgical loupes were used in all the surgeries performed by ENT-HNS vs. 85% by the ES. Parathyroid glands were identified in all the surgeries performed by ENT-HNS versus 95% by ES. Neuromonitoring was used in all the surgeries performed by ENT-HNS, and none by the ES. Vocal cord paralysis developed in two patients of ES versus none in the ENT-HNS. Mean operative duration for total thyroidectomy in ENT-HN surgeries, 183.7 min vs. 151 min in the ES. The mean hospital stay of patients was 3.6 ± 1.6 days for ENT-HNS, and 5.45 ± 3 days for ES. Identification of parathyroid gland and recurrent laryngeal nerve by neuromonitoring and surgical loupes may increase operative time but decrease the rate of vocal cord paralysis and increases the chance of parathyroid gland identification.

Surgical Management of Carotid Body Tumor and Risk Factors of Postoperative Cranial Nerve Injury

BACKGROUND

To identify risk factors of postoperative cranial nerve injury (CNI) following surgical treatment of a carotid body tumor (CBT) by retrospective analysis of the data during the past decade in our center.

METHODS

From May 2008 to September 2018, patients who underwent CBT resections at the Department of Vascular Surgery, Zhongshan Hospital, Fudan University, were included in the study. Demographic, preoperative, intraoperative, and postoperative data of patients were collected and analyzed. Univariate and multivariate logistic regression analyses were performed to identify the independent risk factors of CNI.

RESULTS

A total of 203 CBTs were excised in 196 patients; 17.7% was classified as Shamblin I, 59.1% as Shamblin II, and 23.2% as Shamblin III. CNI after surgery occurred in 57 (28.1%) patients. Postoperative CNI, external carotid artery (ECA) ligation, internal carotid artery (ICA) reconstruction, tumor volume, and established blood loss (EBL) were significantly correlated with Shamblin classification. On univariate analysis, there were statistically significant differences in Shamblin classification (p = 0.002), tumor volume (p = 0.014), number of lymph nodes removed (NOLNR) (p < 0.001), and EBL (p = 0.019) between two groups (with and without CNI after surgery). Multivariate logistic regression analysis revealed a significant positive correlation between CNI and Shamblin III (AOR, 4.744; 95% CI, 1.21-18.56; p = 0.025) and NOLNR (AOR, 0.25; 95% CI, 1.23-1.46 for each three-interval increase, p < 0.001).

CONCLUSIONS

Shamblin III and NOLNR are independent risk factors of CNI for patients who undergo CBT resections.

Early detection of recurrent laryngeal nerve damage using intraoperative nerve monitoring during thyroidectomy

Objective

This study aimed to investigate risk factors for early recurrent laryngeal nerve (RLN) damage during thyroid surgery with intraoperative nerve monitoring (IONM) technology to avoid RLN damage during surgery.

Methods

Data were retrospectively collected from 93 patients who underwent thyroidectomy at Beijing Hospital. All operations were performed by the same surgeon. A four-step procedure of IONM was used during the operation to determine the amplitude and latency of the RLN.

Results

The majority (51.6%) of patients who underwent surgery had thyroid carcinoma. Lymphadenectomy was carried out in 55 (59.1%) patients. A strong association was observed between temporary injury of the RLN and the extent of resection. The risk of temporary injury of the RLN during total thyroidectomy was three times that during right thyroid lobectomy (odds ratio = 3.13). The results of left lobectomy were also different from those of right lobectomy because the RLN was more likely to be damaged during left lobectomy.

Conclusions

Assessment of the amplitude and latency of the RLN can help to assess the integrity of the RLN. The extent of resection affects the functional integrity of the RLN.

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.

Transcranial motor-evoked potentials of laryngeal muscles for intraoperative neuromonitoring of the vagus nerve during thyroid surgery

PURPOSE

The aim of this study was to elucidate normative features of vagal motor-evoked potentials (MEPs) induced by transcranial electrical stimulation (TES) and to determine the influence of functional decline of the recurrent laryngeal nerve (RLN) on vagal MEPs during thyroid surgery.

METHODS

A total of 54 patients undergoing elective thyroid surgery under general anesthesia were enrolled in this study. Vagal MEPs induced by TES were measured from the vocal cord using one of two types of electrodes (wire type or wide and flat type) mounted on an endotracheal tube. We investigated the effects of stimulation intensity and train pulse number on vagal MEP amplitude, the time course of vagal MEP amplitude during surgery, and the effects of functional decline of the RLN on vagal MEPs.

RESULTS

The success rate of vagal MEP monitoring with wide- and flat-type electrodes was significantly higher than that with wire-type electrodes. Reliable vagal MEPs were obtained at a stimulation intensity of approximately 300 V with 3 or more pulses in 91% of the patients without preoperative RLN palsy (RLNP), and the amplitude was augmented with increasing stimulation intensity and train pulse number. Vagal MEP amplitude decreased during thyroid surgery and then partially recovered at the end of surgery. Vagal MEP amplitude recorded from the electrode ipsilateral to preoperative RLNP was significantly lower than that on the contralateral intact side.

CONCLUSION

Vagal MEPs induced by TES can be obtained with a high success rate during thyroid surgery and would reflect functional status of the RLN.

Thyroid surgery for differentiated thyroid cancer - recent advances and future directions

Population-based studies have demonstrated that an increasing number of incidental thyroid nodules are being identified. The corresponding increase in thyroid-based diagnostic procedures, such as fine-needle aspiration biopsy, has in part led to an increase in the diagnoses of thyroid cancers and to more thyroid surgeries being performed. Small papillary thyroid cancers account for most of this increase in diagnoses. These cancers are considered to be low risk because of the excellent patient outcomes, with a 5-year disease-specific survival of >98%. As a result, controversy remains regarding the optimal management of newly diagnosed differentiated thyroid cancer, as the complications related to thyroidectomy (primarily recurrent laryngeal nerve injury and hypoparathyroidism) have considerable effects on patient quality of life. This Review highlights current debates, including undertaking active surveillance versus thyroid surgery for papillary thyroid microcarcinoma, the extent of thyroid surgery and lymphadenectomy for low-risk differentiated thyroid cancer, and the use of molecular testing to guide decision-making about whether surgery is required and the extent of the initial operation. This Review includes a discussion of current consensus guideline recommendations regarding these topics in patients with differentiated thyroid cancer. Additionally, innovative thyroidectomy techniques (including robotic and transoral approaches) are discussed, with an emphasis on patient preferences around decision-making and outcomes following thyroidectomy.

Intraoperative Neuromonitoring During Thyroid Surgery: The Effect of Surgical Positioning

Intraoperative neuromonitoring during thyroid surgery has been used to successfully prevent permanent neurological injury by early identification of anatomical variants. Proper interpretation of neuromonitoring data requires knowledge of what factors might affect the data. In this study, we examined the effect of surgical positioning on the latency and amplitude of neural recordings made from the vocalis muscle during thyroid surgery. A retrospective review was performed of 145 patients who underwent thyroid surgery. Eighty-three had open cervical procedures, and 62 had robotic-assisted transaxillary procedures. Intraoperative neuromonitoring recordings were made by stimulation of the vagus and recurrent laryngeal nerves for both groups. Ultrasound measurements were made of a subset of the transaxillary patients immediately before and after arm positioning. Groups differed only on right-sided recordings. Patients with transaxillary surgeries had significantly shorter latencies evoked from the vagus nerve. We found that vagus nerve-evoked latencies were also correlated to ultrasound measurements of the nerves. Surgical positioning during thyroid surgery is a factor that may affect intraoperative neuromonitoring data and should be taken into account by the surgeon during interpretation.

Protective Effects of Intraoperative Nerve Monitoring (IONM) for Recurrent Laryngeal Nerve Injury in Thyroidectomy: Meta-analysis

Recurrent laryngeal nerve (RLN) injury is an intractable complication of thyroidectomy. Intraoperative nerve monitoring (IONM) was designed to prevent RLN injury. However, the results concerning the protective effect of IONM on RLN injury are still controversial. We searched all eligible databases from 1980 to 2017. Meta-analysis was performed to evaluate the effect of IONM on RLN injury. Sensitivity analysis was also conducted to check the stability of our results. There were 34 studies included in the analysis. Overall analysis found a significant decrease in total injury (RR = 0.68, 95%CI: 0.55 to 0.83), transient injury (RR = 0.71, 95%CI: 0.57 to 0.88), and permanent injury (RD = −0.0026, 95%CI: −0.0039 to −0.0012) with IONM. Subgroup analysis found IONM played a preventive role of total, transient and permanent injury in patients undergoing bilateral thyroidectomy. IONM also reduced the incidence of total and transient injury for malignancy cases. Operations with IONM were associated with fewer total and transient RLN injuries in operation volume < 300 NARs per year and fewer total and permanent RLN injuries in operation volume ≥ 300 NARs per year. The application of IONM could reduce the RLN injury of thyroidectomy. Particularly, we recommend routine IONM for use in bilateral operations and malignancy operations.

Effect of nerve monitoring on complications of thyroid surgery

OBJECTIVE:

The most frequent and critical complications of thyroid surgery are recurrent laryngeal nerve palsy and hypocalcemia. In first years of the 21st century, intraoperative neuromonitoring (IONM) was introduced as a new technique to avoid the recurrent laryngeal nerve (RLN) injury. However, the role and the benefits of IONM are still controversial. In this study, we aimed to compare the postoperative complication rates during thyroid surgery with IONM usage (Group 1) and conventional direct visual technique without IONM usage (Group 2).

METHODS:

We conducted retrospective review of all patients undergoing thyroid surgery in Lütfiye Nuri Burat State Hospital General Surgery Department between 2014 and 2016 years. Patients have been classified in to two groups: Group 1 and 2.

RESULTS:

Overall, 191 patients were included in the study; Group 1 comprised 79 patients and Group 2 comprised 112 patients. Unilateral RLN paralysis was observed in 7 patients in Group 1 (8.9%) and 15 patients in Group 2 (13.4%) without any significant difference between the groups (p=0.368). Hypocalcemia was encountered in 5 patients (6.3%) in Group 1 and 18 patients (16.1%) in Group 2; this difference was statistically significant (p=0.045). Other complications (such as hematoma and suture reaction) were not significantly different. Operation time was found to be significantly shorter in Group 1 (Mean time, 93.08 min) than in Group 2 (116.54 min) (p=0.03).

CONCLUSION:

Proven effect of IONM on RLN paralysis is still controversial. However, easy identification of RLN, which gives more confidence to surgeon, and shorter operation time may be factors to lower hypocalcemia rates.

Utility of intraoperative nerve monitoring in thyroid surgery: 20-year experience with 1418 cases

PURPOSE

The efficacy of intraoperative nerve monitoring is controversial in the literature. This study of a single surgeon's experience seeks to determine if the use of intraoperative nerve monitoring influences recurrent laryngeal nerve injury during thyroid surgery.

METHODS

Six hundred fifty-seven patients with normal pre-operative vocal fold function underwent thyroid surgery without the use of intraoperative nerve monitoring from September 1997 to January 2007, while 761 patients underwent thyroid surgery from February 2007 to February 2016 with routine use of nerve monitoring. Patients were followed for a minimum of 6 months after surgery, and postoperative nerve function was determined by fiberoptic laryngoscopy. A Fisher test was used to determine if nerve injury was statistically different between both groups.

RESULTS

In patients operated on without nerve monitoring, 21 patients were found to have postoperative vocal fold paralysis with nine regaining functioning. In patients operated on with nerve monitoring, 27 were found to have vocal fold dysfunction with 17 regaining function. Fisher test analysis, both with and without patients regaining function, showed no difference in nerve injury between groups (p > 0.05, p > 0.05).

CONCLUSION

Intraoperative monitoring during thyroidectomy may not prevent injury to the recurrent laryngeal nerve.