Efficacy of Intraoperative Neuromonitoring in Reoperation for Recurrent Thyroid Cancer Patients

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.

Predicting recurrent laryngeal nerve invasion by preoperative ultrasonography in patients with thyroid carcinoma

Background

For thyroid cancer staging, evaluation of extent of local invasion, including recurrent laryngeal nerve (RLN), may assist surgical decision-making.

Methods

This prospective study evaluated patients who underwent thyroidectomy at a single tertiary-level academic institution. Patients with complete clinical information and ultrasound imaging of thyroid carcinoma and RLN were enrolled. Those who had thyroidectomy before or did not fit the above conditions were excluded. Patients were assigned to either a development or validation cohort. Development of models was constructed in a primary cohort based on preoperative ultrasound features and clinicodemographic data from August 2020 to December 2021. Validation of the models was then performed on an independent cohort between January and March of 2022. Multivariate logistic regression and nomograms were mainly used for statistical analysis.

Results

Using data from 816 patients (80 RLN invasion), we built nomogram 1 based on age [95% confidence interval (CI): 1.315 to 145.933, P=0.029], body mass index (BMI; 95% CI: 1.228 to 10.874, P=0.020), tumor size (95% CI: 4.677 to 1,373.1, P=0.002), tumor adjacent to medial (95% CI: 1.816 to 26.713, P=0.005) and posterior thyroid capsules (95% CI: 5.567 to 756.583, P=0.001), and distance <1 mm between tumor and the RLN (95% CI: 10.389 to 826.746, P<0.001). Nomogram 2 was built based on tumor adjacent to the posterior thyroid capsule (95% CI: 2.922 to 53,074.51, P=0.017), distance <1 mm between tumor and the RLN (95% CI: 1.478 to 1,241.646, P=0.029), and loss of typical fascicular echotexture of the RLN along the long axis (95% CI: 35.11 to 53,272.81, P<0.001). In the validation cohort, nomogram 1 and 2 showed sensitivities of 94.74% and 57.89%, specificities of 74.12% and 95.29%, positive predictive values (PPV) of 45.00% and 73.26%, negative predictive values (NPV) of 98.43% and 91.03%, accuracies of 76.92% and 88.46%, and C-indices of 0.86 and 0.89.

Conclusions

Preoperative ultrasound is a feasible approach to evaluate RLN invasion in patients with thyroid carcinoma. Nomogram 1 may sensitively identify the risk of RLN invasion, and it may be checked using the more specific and accurate nomogram 2 to reduce false positives.

The learning curve for gasless transaxillary posterior endoscopic thyroidectomy for thyroid cancer: a cumulative sum analysis

Gasless transaxillary posterior endoscopic thyroidectomy (GTPET) is a new approach for thyroid cancer. It allows en bloc resection of the thyroid and central lymph nodes. Few studies have reported on the learning curve for GTPET.We examined the learning curve of GTPET for thyroid cancer by cumulative sum (CUSUM) analysis by retrospectively analyzing patients who underwent hemithyroidectomy with ipsilateral central neck dissection between December 2020 and September 2021 at a tertiary medical center, including the first patient. Moving average analysis and sequential time-block analysis were used for validation. Data on the clinical factors between the two periods were compared. In the overall cohort, the average time for GTPET for thyroid cancer was 113.25 min to harvest an average of 6.4 central lymph nodes. The CUSUM curve of the operative time indicated an inflection point after 38 patients. Moving average analysis and sequential time-block analysis validated the number of procedures needed for GTPET proficiency. (124.05 min vs. 107.63 min for the unproficient period vs. proficient period, respectively; P < 0.001) The number of retrieved lymph nodes was not associated with a certain level of proficiency per the learning curve. The main complication during the surgeon's unproficient period was transient hoarseness (3/38), which was similar to that in their proficient period (2/73, p = 0.336). Proficiency in GTPET is associated with performing more than 38 procedures. Standard course training and instruction on careful management are required prior to introducing the procedure.

Intraoperative neuromonitoring of the recurrent laryngeal nerve is indispensable during complete endoscopic radical resection of thyroid cancer: A retrospective study

Objective

Complete endoscopic radical resection of thyroid cancer, especially through the areolar approach, can achieve curative and acceptable cosmetic effects in patients with differentiated thyroid carcinoma. However, some inherent characteristics of endoscopic procedures hamper functional protection of the recurrent laryngeal nerve (RLN). Intraoperative neuromonitoring (IONM) is considered the most important accessory to protect the nerves during conventional radical thyroidectomy. This study aimed to evaluate the feasibility and necessity of IONM during complete endoscopic radical resection of thyroid cancer.

Methods

A total of 106 patients with differentiated thyroid carcinoma were enrolled in the study between February 2013 and April 2018. Based on the use of the IONM technique, all patients were divided into the IONM (n = 54) and non-IONM groups (n = 52). Overall, 66 RLNs were involved in the IONM group, and 61 RLNs were involved in the non-IONM group. The time and ratio of RLN identification and the number of transient and permanent RLN injuries between both groups were compared.

Results

Compared to the non-IONM group, the IONM group required less time for RLN identification (3.05 ± 1.58 vs. 9.36 ± 4.82 min, p < .01). The ratio of RLN identification in the IONM group was much higher than that in the non-IONM group (100.00% vs. 88.52%, p = .01). A significant difference was observed in RLN transient injury between the two groups (one case accounting for 1.51% in the IONM group vs. eight cases accounting for 13.11% in the non-IONM group; p = .03).

Conclusion

IONM significantly improved RLN identification and reduced transient RLN injuries during complete endoscopic radical resection.

Level of Evidence

3b.

The value of intraoperative nerve monitoring against recurrent laryngeal nerve injury in thyroid reoperations

Reoperative thyroidectomy is challenging for surgeons because of the higher incidence of recurrent laryngeal nerve (RLN) palsy. RLN identification is the gold standard during thyroidectomy; however, it is sometimes difficult to perform thyroid reoperations. In recent years, intraoperative nerve monitoring (IONM) has gained increased acceptance, and the use of IONM can be a valuable adjunct to visual identification. The aim of this study was to evaluate the value of IONM during thyroid reoperation.A total of 109 patients who met our criteria at the Affiliated Hospital of Hangzhou Normal University from January 2010 to June 2020 were retrospectively analyzed and divided into the IONM group and the visualization-alone group (VA group) according to whether neuromonitoring was used during the operation. The patients' characteristics, perioperative data, and intraoperative information including the RLN identification, time of RLNs confirmation, operative time, intraoperative blood loss, and the rate of RLN injury were collected.Sixty-five procedures (94 RLNs at risk) were performed in the IONM group, whereas 44 (65 RLNs at risk) were in the VA group. The rate of RLN identification was 96.8% in the IONM group and 75.4% in the VA group (P < .05). The incidence of RLN injury was 5.3% in the IONM group and 13.8% in the VA group (P > .05). The incidence of surgeon-related RLN injury rate was 0% in the IONM group compared to 7.7% in the VA group (P < .05), but the tumor-related or scar-related RLN injury rate between the 2 groups were not significantly different (4.3% vs 3.1%, 1.1% vs 3.1%, P > .05).IONM in thyroid reoperation was helpful in improving the RLN identification rate and reducing the surgeon-related RLN injury rate, but was ineffective in reducing the tumor-related and scar-related RLN injury rate. In the future, multicenter prospective studies with large sample sizes may be needed to further assess the role of IONM in thyroid reoperations.