Intraoperative neural monitoring in thyroid cancer surgery

Central Compartment Lymph Nodes Have Distinct Metastatic Patterns in Different Age Groups

BACKGROUND AND PURPOSE

Central compartment lymph node metastasis (CLNM) is a manifestation of tumor aggressiveness and an indicator of tumor prognosis. The purpose of this study was to construct a nomogram for evaluating CLNM patterns in papillary thyroid carcinoma (PTC) in different age groups.

METHOD

A total of 907 patients diagnosed with PTC from August 2014 to December 2018 were enrolled. A nomogram illustrating CLNM was generated using the results of multivariate logistic regression analysis.

RESULTS

According to the best Youden index, we set the cut-off age at 45 years. Multivariate logistic regression analysis showed that in patients aged <45 years, large tumor size (P<0.05), extra-thyroid extension (P<0.05) and thyroglobulin level >40 ng/ml (OR=2.985, 95% CI 1.379-6.462; P<0.05) were independent risk factors; meanwhile, Hashimoto's thyroiditis (OR=0.532, 95% CI 0.324-0.874; P<0.05) was a protective factor of CLNM. In the subgroup with age ≥45 years, large tumor size (P<0.05), extra-thyroid extension (P<0.05), unclear margin (OR=1.604, 95% CI 1.065-2.416; P<0.05), male gender (OR=2.009, 95% CI 1.257-3.212; P<0.05) were independent risk factors for CLNM. In the subgroup with age <45 years, an area under the curve (AUC) of 0.729 (95% CI 0.680-0.777); P<0.05) was obtained. In the ≥45 years subgroup, the AUC was 0.668 (95% CI 0.619-0.716; P<0.05).

CONCLUSION

CLNM of PTC in different age groups may have distinct patterns. Based on the potential risk factors for CLNM in patients with different age stratification, a user-friendly predictive model was established.

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.

Meta-analysis on continuous nerve monitoring in thyroidectomies

In the last decade, the introduction of continuous intraoperative recurrent laryngeal nerve (RLN) monitoring (C-IONM) has enabled the operator to verify the functional integrity of the vagus nerve-recurrent laryngeal nerve (VN-RLN) axis in real-time. We aim to present the current evidence on C-IONM utility for thyroid surgery by conducting the first meta-analysis on this technique. A systematic review of literature was conducted by two independent reviewers via Ovid in the Medline, EMBASE, and Cochrane reviews databases. The search was limited to human subject research in peer-reviewed articles of all languages published between Jan 1946 and April 2020. Medical subject headings (MeSH) terms utilized were thyroid surgery, thyroidectomies, recurrent laryngeal nerve, vagal nerve, monitor, and stimulation. Thirty-eight papers were identified from Ovid, another six papers were identified by hand-search. A random effect meta-analysis was performed with assessment of heterogeneity using the I² value. A total of 23 papers that investigated the use of continuous vagal nerve monitoring during thyroid surgery were identified. The proportion of nerves at risk (NAR) with temporary RLN paralysis postoperation was 2.26% (95% CI: 1.6-2.9, I²  = 37). The proportion of NAR with permanent RLN palsy postoperation was 0.05% (95% CI: 0.08-0.2, I²  = 0). In this meta-analysis, there is one case of temporary vagal nerve paralysis secondary to VN electrode dislodgement, and a case of hemodynamic instability manifested in bradycardia and hypotension in the initial phase of surgery shortly after calibration. C-IONM is a safe and effective means by which RLN paralyses in thyroid surgery can be reduced.

A new anesthesia scheme for parathyroidectomy under neuromonitoring: a retrospective cohort study

Background

Parathyroidectomy under nerve monitoring has been carried out for nearly ten years in the China-Japan Union Hospital of Jilin University. We retrospectively evaluated patients' prognosis with secondary hyperparathyroidism (SH) under neuro- and non-neuro-monitored parathyroidectomy anesthesia. The purpose of this study is to summarize and introduce a new anesthesia scheme for parathyroidectomy under nerve monitoring.

Methods

From January 2000 to December 2019, 200 patients with SH in the China-Japan Union Hospital of Jilin University were retrospectively analyzed. Among them, 100 patients underwent parathyroidectomy under neurological monitoring (Group A), and 100 patients underwent parathyroidectomy without neurological monitoring (Group B). The dosage of muscle relaxant, parathyroid hormone (PTH), serum calcium, phosphorus, urea, creatinine, and alkaline phosphatase (ALP) was recorded before surgery (T0), after surgery (T1), at discharge (T2), during skin incision (Ta), at four parathyroidectomies (Tb), and 10 min after total removal. The levels of PTH were measured at four-time points (Tc) and 30 minutes (Td) after complete resection.

Results

After screening and propensity score match (PSM), the data of 92 patients were analyzed. Group A's muscle relaxant dose was significantly less than Group B; the length of hospital stay in Group A was significantly lower than in Group B (P<0.05). The serum calcium levels, phosphorus, urea, and creatinine at T2 in Group A were lower than those in Group B (P<0.05).

Conclusions

Parathyroid nerve monitoring technology combined with preoperative complete anesthesia scheme, anesthesia induction with one time ED95 (95% effective drug dose) cis-atracurium, end breath gas, and sevoflurane maintenance anesthesia under BIS monitoring can improve the prognosis of patients, shorten the length of hospital stay, and is effective and safe.

Efficacy of Intraoperative Neuromonitoring in Reoperation for Recurrent Thyroid Cancer Patients

BACKGROUND

The use of intraoperative neuromonitoring (IONM) in thyroid surgery to preserve recurrent laryngeal nerve (RLN) function has been widely accepted. We aimed to evaluate the usefulness of IONM in reoperation for recurrent thyroid cancer patients to help identify the RLN and prevent vocal cord palsy (VCP).

METHODS

We analyzed 121 consecutive patients (with IONM group, 48 patients; without IONM group, 73 patients) who underwent reoperation for recurrent thyroid cancer after total thyroidectomy from January 2009 to March 2019 in our institution without VCP due to previous operations. Data including age, sex, number of previous operations, histologic subtype of the malignancy at the initial operation, operation time, RLNs at risk, difficulty of RLN identification, surgical procedure, VCP, and other postoperative complications were reviewed. Vocal cord movement evaluations were performed preoperatively and at 2 weeks postoperatively to evaluate RLN function. In patients with VCP, additional evaluations were performed. VCP exceeding 12 months after surgery was considered permanent VCP.

RESULTS

VCP was observed in six (12.5%) and 16 (21.9%) patients with and without IONM (P=0.189). Transient and permanent VCP were found in three (6.3%) and three (6.3%) patients with IONM (P=0.098 and P=0.982, respectively) versus in 12 (16.4%) and four (5.5%) patients without IONM.

CONCLUSION

The incidence of transient VCP seems to be lower in reoperations with IONM; however, there was no statistical significances. Further study will be needed to ascertain the efficacy of IONM in reoperation for recurrent thyroid cancer patients.

Immediate Intraoperative Repair of the Recurrent Laryngeal Nerve in Thyroid Surgery

OBJECTIVES

Recurrent laryngeal nerve (RLN) injury is a recognized risk during thyroid and parathyroid surgery and can result in significant morbidity. The aim of this review paper is to consider the optimal approach to the immediate intraoperative repair of the RLN during thyroid surgery.

METHODS

A PubMed literature search was performed from inception to June 2020 using the following search strategy: immediate repair or repair recurrent laryngeal nerve, repair or reinnervation recurrent laryngeal nerve and immediate neurorraphy or neurorraphy recurrent laryngeal nerve.

RESULTS

Methods of immediate intraoperative repair of the RLN include direct end-to-end anastomosis, free nerve graft anastomosis, ansa cervicalis to RLN anastomosis, vagus to RLN anastomosis, and primary interposition graft. Techniques of nerve repair include micro-suturing, use of fibrin glue, and nerve grafting. Direct micro-suture is preferable when the defect can be repaired without tension. Fibrin glue has also been proposed for nerve repair but has been criticized for its toxicity, excessive slow reabsorption, and the risk of inflammatory reaction in the peripheral tissues. When the proximal stump of the RLN cannot be used, grafting could be done using transverse cervical nerve, supraclavicular nerve, vagus nerve, or ansa cervicalis.

CONCLUSIONS

Current evidence is low-level; however, it suggests that when the RLN has been severed, avulsed, or sacrificed during thyroid surgery it should be repaired intraoperatively. The immediate repair has on balance more advantages than disadvantages and should be considered whenever possible. This should enable the maintenance of vocal cord tone, better and prompter voice recovery and avoidance of aspiration. Laryngoscope, 131:1429-1435, 2021.

Intraoperative monitoring of the femoral and sciatic nerves in total hip arthroplasty with high-riding developmental dysplasia

AIMS

This study aimed to explore whether intraoperative nerve monitoring can identify risk factors and reduce the incidence of nerve injury in patients with high-riding developmental dysplasia.

PATIENTS AND METHODS

We conducted a historical controlled study of patients with unilateral Crowe IV developmental dysplasia of the hip (DDH). Between October 2016 and October 2017, intraoperative nerve monitoring of the femoral and sciatic nerves was applied in total hip arthroplasty (THA). A neuromonitoring technician was employed to monitor nerve function and inform the surgeon of ongoing changes in a timely manner. Patients who did not have intraoperative nerve monitoring between September 2015 and October 2016 were selected as the control group. All the surgeries were performed by one surgeon. Demographics and clinical data were analyzed. A total of 35 patients in the monitoring group (ten male, 25 female; mean age 37.1 years (20 to 46)) and 56 patients in the control group (13 male, 43 female; mean age 37.9 years (23 to 52)) were enrolled. The mean follow-up of all patients was 13.1 months (10 to 15).

RESULTS

The two groups had no significant differences in preoperative data. In the monitoring group, ten nerve alerts occurred intraoperatively, and no neural complications were detected postoperatively. In the control group, six patients had neural complications. The rate of nerve injury was lower in the monitoring group than in the control group, but this did not achieve statistical significance. The degree of leg lengthening was significantly greater in the monitoring group than in the control group. In further analyses, patients who had previous hip surgery were more likely to have intraoperative nerve alerts and postoperative nerve injury.

CONCLUSION

Nerve injury usually occurred during the processes of exposure and reduction. The use of intraoperative nerve monitoring showed a trend towards reduced nerve injury in THA for Crowe IV DDH patients. Hence, we recommend its routine use in patients undergoing leg lengthening, especially in those with previous hip surgery. Cite this article: Bone Joint J 2019;101-B:1438-1446.

Intraoperative Nerve Monitoring for Tarsal Tunnel Decompression: A Surgical Technique to Improve Outcomes

The aim of the current study was to evaluate the effectiveness of intraoperative neuromonitoring (INM) as an adjunct in performing tarsal tunnel decompression surgery. We reviewed 38 patients who met inclusion criteria. INM was used to measure the voltage of the abductor hallucis and digiti quinti muscles both before and after decompression. Observed changes intraoperatively were acute and within minutes of the decompression performed by the surgeon. Patient outcomes were ascertained from clinical findings and classified as excellent, fair, or poor. Patient outcomes and the voltage change were measured and assessed for association, and statistically significant differences were found between outcome groups. Of the 38 patients, 29 (76%) had excellent outcomes, with a mean change in microvolts of 2088.28 ± 1172.44 (684%) (p = .0004) and 2173.24 ± 1228.39 (742%) (p = .0014) for abductor hallucis and abductor digiti quinti, respectively. The study supports INM as a useful adjunct in performing tarsal tunnel decompression.

Intraoperative nerve monitoring reduces recurrent laryngeal nerve injury in geriatric patients undergoing thyroid surgery

OBJECTIVE

This research was aimed to investigate whether the intraoperative nerve monitoring (IONM) can reduce the incidence of recurrent laryngeal nerve (RLN) injury in geriatric patients undergoing thyroid surgery.

METHODS

This retrospective cohort study included 522 geriatric patients undergoing thyroid surgery between January 2013 and June 2016 in the Sun Yat-sen Memorial Hospital. Patients with IONM during the surgery (n = 340) were compared with patients without IONM (n = 212). RLN injury was verified by direct or indirect laryngoscope and relative factors for injury would be retrospectively analyzed.

RESULTS

The use of IONM group showed significant reduction in both total and transient RLN injury incidence, when compared with that in control group (1.76 versus 4.72%, p = .01 and 1.32 versus 3.67%, p = .03, respectively). However, the permanent RLN injury incidence did not show difference between the two groups (p = .3).

CONCLUSIONS

Our finding showed the use of IONM resulted in significantly reduction in RLN injury incidence. The technology of IONM is safe and convenient to detect, track and monitor the complete function of RLN and to provide the guidance for the surgeons during the thyroid surgery in geriatric patients, who are at high risk of RLN injury.

Comprehensive management of recurrent thyroid cancer: An American Head and Neck Society consensus statement: AHNS consensus statement

This American Head and Neck Society (AHNS) consensus statement focuses on the detection and management of recurrent thyroid cancer. This document describes the radiologic approach to defining structural recurrent disease and the operative and nonoperative rationale in addressing identified structural disease to create equipoise in the personalized treatment strategy for the patient. The recommendations of this AHNS multidisciplinary consensus panel of the American Head and Neck Society are intended to help guide all multidisciplinary clinicians who diagnose or manage adult patients with thyroid cancer. The consensus panel is comprised of members of the American Head and Neck Society and its Endocrine Surgical Committee, and there is representation from medical endocrinology and both national and international surgical representation drawn from general/endocrine surgery and otolaryngology/head and neck surgery. Authors provided expertise for their respective sections, and consensus recommendations were made regarding the evaluation and treatment of recurrent thyroid cancer. Evidence-based literature support is drawn from thyroid cancer studies, recurrent thyroid cancer studies, and American Thyroid Association (ATA) guidelines. The manuscript was then distributed to members of the American Head and Neck Society Endocrine Committee and governing counsel for further feedback. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1862-1869, 2016.

Management of Invasive Differentiated Thyroid Cancer

BACKGROUND

Invasive disease is a poor prognostic factor for patients with differentiated thyroid cancer (DTC). Uncontrolled central neck disease is a common cause of distressing death for patients presenting in this manner. Advances in assessment and management of such cases have led to significant improvements in outcome for this patient group. This article reviews the patterns of invasion and a contemporary approach to investigation and treatment of patients with invasive DTC.

SUMMARY

Aerodigestive tract invasion is reported in around 10% of case series of DTC. Assessment should include not only clinical history and physical examination with endoscopy as indicated, but ultrasound and contrast-enhanced cross-sectional imaging. Further studies including positron emission tomography should be considered, particularly in recurrent cases that are radioactive iodine (RAI) resistant. Both the patient and the extent of disease should be carefully assessed prior to embarking on surgery. The aim of surgery is to resect all gross disease. When minimal visceral invasion is encountered early, "shave" procedures are recommended. In the setting of transmural invasion of the airway or esophagus, however, full thickness excision is required. For intermediate cases in which invasion of the viscera has penetrated the superficial layers but is not evident in the submucosa, opinion is divided. Early reports recommended an aggressive approach. More recently authors have tended to recommend less aggressive resections with postoperative adjuvant therapies. The role of external beam radiotherapy continues to evolve in DTC with support for its use in patients considered to have RAI-resistant tumors.

CONCLUSIONS

Patients with invasive DTC require a multidisciplinary approach to investigation and treatment. With detailed assessment, appropriate surgery, and adjuvant therapy when indicated, this patient group can expect durable control of central neck disease, despite the aggressive nature of their primary tumors.

Identifying a Safe Range of Stimulation Current for Intraoperative Neuromonitoring of the Recurrent Laryngeal Nerve: Results from a Canine Model

Background:

Intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) has been widely applied during thyroid surgery. However, the safe range of stimulation intensity for IONM remains undetermined.

Methods:

Total thyroidectomies were performed on twenty dogs, and their RLNs were stimulated with a current of 5–20 mA (step-wise in 5 mA increments) for 1 min. The evoked electromyography (EMG) of vocal muscles before and after supramaximal stimulation were recorded and compared. Acute microstructural morphological changes in the RLNs were observed immediately postoperatively under an electron microscope.

Results:

The average stimulating threshold for RLNs stimulated with 15 mA and 20 mA showed no significant changes compared to the unstimulated RLNs (15 mA group: 0.320 ± 0.123 mA vs. 0.315 ± 0.097 mA, P = 0.847; 20 mA group: 0.305 ± 0.101 mA vs. 0.300 ± 0.103 mA, P = 0.758). Similar outcomes were shown in average evoked EMG amplitude (15 mA group: 1,026 ± 268 μV vs. 1,021 ± 273 μV, P = 0.834; 20 mA group: 1,162 ± 275 μV vs. 1,200 ± 258 μV, P = 0.148). However, obvious acute microstructural morphological changes were observed in the nerves that were stimulated with 20 mA.

Conclusions:

A stimulation intensity less than 15 mA might be safe for IONM of the RLN.

The weepy nerve-different sensitivity of left and right recurrent laryngeal nerves under tensile stress in a porcine model

PURPOSE

Recurrent laryngeal nerve palsy in thyroid surgery is still a threatening complication. Our aim was to analyze the impact of prolonged tensile stress on the recurrent laryngeal nerve (RLN) in an animal model using continuous intraoperative neuromonitoring (C-IONM).

METHODS

Constant tensile stress was applied to left and right RLNs in 20 pigs (40 RLN). In a pilot study, five animals were subjected to a tensile force of 0.34 ± 0.07 N for 10 min and changes in amplitude were documented using C-IONM. In the main study, a force of 1.2 N was applied until the signal amplitude was reduced by 85 %, in 15 pigs. Nerve conductivity was analyzed by threshold current measurements.

RESULTS

Good correlation was found between stress and amplitude decrease in the pilot study as well as between signal decrease and duration of trauma in the main study. Great variations were found inter- and intra-individually. These variations were most prominent at 85 % signal reduction (median 36 min, range 0.3-171 min). There was no side specificity (left 0.3-171 min, right 0.3-168 min, respectively, p = 0.19). However, in each individual animal, there was a sensitive (0.3-98.9 min) and less sensitive nerve (26.8-171 min). These differences became highly significant at 85 % of signal reduction (p = 0.008), where the vulnerability is 1.4 to 146.4 times higher on one side (mean 4.3).

CONCLUSIONS

Our study demonstrates the presence of a sensitive RLN that was 4.3 times more vulnerable than the contralateral nerve (range 1.4-146.4 times, p = 0.008). Thus, the right and the left nerves cannot be assumed to be of equal sensitivity to trauma. In our data, the more sensitive nerve does not occur predominantly on one side and was named the "weepy nerve."

The learning curve for intraoperative neuromonitoring of the recurrent laryngeal nerve in thyroid surgery

Purpose

Intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) is often used in thyroid surgery. However, this procedure is complex and requires a learning period to master the technique. The aim of the study was to evaluate the learning curve for IONM.

Methods

A 3-year period (2012–2014) of working with IONM (NIM3.0, Medtronic) was prospectively analyzed with a special emphasis on comparing the initial implementation phase in 2012 (101 patients, 190 RLNs at risk) with subsequent years of IONM use in 2013 (70 patients, 124 RLNs at risk) and 2014 (65 patients, 120 RLNs at risk).

Results

The rate of successful IONM-assisted RLN identification increased gradually over the 3-year study period (92.11 % in 2012 vs. 95.16 % in 2013 vs. 99.16 % in 2014; p = 0.022), with a corresponding decrease in the rate of technical problems (12.87, 4.3, and 4.6 %, respectively; p = 0.039). The rate of RLN injuries tended to decrease over time: 3.68, 1.55, and 0.83 %, respectively (p = 0.220). Between 2012 and 2014, increases in the sensitivity (71.4 vs. 100 %), specificity (98 vs. 99 %), positive predictive value (62.5 vs. 75 %), negative predictive value (98 vs. 100 %), and overall accuracy of IONM (97.4 vs. 99.6 %) were observed (p = 0.049). Increasing experience with IONM resulted in more frequent utilization of total thyroidectomy (92 % in 2012 vs. 100 % in 2013–2014; p = 0.004).

Conclusions

There was a sharp decrease in the number of technical problems involving equipment setup from 2012 to 2014.

Prognostic value of intraoperative neural monitoring of the recurrent laryngeal nerve in thyroid surgery

Purpose

The diagnostic accuracy of intraoperative recurrent laryngeal nerve (RLN) monitoring (IONM) remains controversial. The aim of this study was to evaluate IONM diagnostic accuracy in prognostication of postoperative nerve function in thyroid surgery.

Methods

This prospective study was conducted in 2011–2013. Five hundred consenting patients qualified for total thyroidectomy with IONM (1000 nerves at risk) using NIM 3.0 Response equipment were included. Laryngoscopy was used to evaluate and follow up RLN injury. The primary outcome was diagnostic accuracy of IONM. The receiver operating characteristics (ROC) were used for evaluation of IONM diagnostic accuracy.

Results

Loss of signal (LOS) occurred in 31 cases, including 25 patients with LOS and corresponding vocal fold paresis found in postoperative laryngoscopy (2.5 %), including 20 (2.0 %) temporary and 5 (0.5 %) permanent nerve lesions. The following diagnostic accuracy values were calculated for the criterion recommended by INMSG (V2 amplitude ≤ 100 μV): sensitivity 92.0 %, specificity 99.3 %, positive predictive value (PPV) 76.7 %, and negative predictive value (NPV) 99.8 %. The ROC curve analysis allowed for calculation of the most optimal criterion in prognostication of postoperative vocal fold paresis, namely, V2 amplitude ≤ 189 μV. For this criterion, PPV was 77.4 %, while NPV was 99.9 %.

Conclusions

Adherence to the standardized protocol recommended by the International Neural Monitoring Study Group allows for optimizing predictive values of IONM in prognostication of postoperative RLN function. Any changes in the cutoff values for the definition of LOS only marginally improve PPV and NPV of IONM and need to be carefully assessed in multicenter studies.

Intermittent intraoperative nerve monitoring in thyroid reoperations: Preliminary results of a randomized, single-surgeon study

BACKGROUND

The purpose of this study was to evaluate whether intermittent intraoperative nerve monitoring (IONM) could reduce the incidence of recurrent laryngeal nerve (RLN) paralysis in thyroid reoperations.

METHODS

Enrolled patients were randomly assigned into the nerve integrity monitor (NIM) group and the control group.

RESULTS

The incidence of temporary RLN paralysis and permanent RLN paralysis was 12.2% and 4.9% in the NIM group compared with 7.0% and 2.3% in the control group (p = .658 and p = .966, respectively). The incidence of surgeon-related paralysis, tumor-related paralysis, and scar-related paralysis was 4.9%, 7.3%, and 4.9% in the NIM group compared with 4.7%, 2.3%, and 2.3% in the control group, respectively (p = 1, p = .575, and p = .966, respectively).

CONCLUSION

Intermittent IONM could not provide additional benefits to reduce the incidence of temporary RLN paralysis and permanent RLN paralysis in thyroid reoperations. It could not reduce the incidence of paralysis caused by unintentional injuries. © 2016 Wiley Periodicals, Inc. Head Neck 38: E1993-E1997, 2016.

Central neck dissection in the treatment of well-differentiated thyroid cancer

Therapeutic central compartment neck dissection (CCND) is required for confirmed nodal metastasis in patients with differentiated thyroid cancer. The need for routine prophylactic CCND in patients with papillary thyroid cancer is controversial. This article presents the current evidence to inform the debate against the background of the recommendations of US and British thyroid cancer guidelines. Potential advantages of pCCND include reduced local recurrence, preventing the need for further central compartment surgery and improved staging. Opponents claim that there is no proven patient benefit and that there is increased risk of recurrent laryngeal nerve injury and hypocalcemia.

[Total thyroidectomy with lymph node dissection of the central compartment for node-positive, capsular invasive papillary thyroid cancer: video contribution]

The aim of radical oncological surgery for nodal metastasized papillary thyroid cancer is, as for other oncological interventions in visceral surgery, the anatomy-related implementation of the concept of en bloc (no touch) resection of the organ bearing the primary tumor together with the first lymph node station, while the structures of the aerodigestive tract, the recurrent laryngeal nerves and parathyroid glands are preserved. The surgical technique is demonstrated in detail with the help of a video of the operation and which is available on-line, the advantages and disadvantages of the technique are discussed.

The nonrecurrent laryngeal nerve: anatomic and electrophysiologic algorithm for reliable identification

OBJECTIVES/HYPOTHESIS

The recurrent laryngeal nerve (RLN) intraoperative monitoring (IONM) provides a new functional dynamic that adds to visual identification of the RLN to optimize its intraoperative management. Intraoperative monitoring has been applied to the initial identification of the RLN. We now apply IONM to the identification of the nonrecurrent laryngeal nerve (NRLN) and provide electrophysiologic and anatomic parameters to facilitate this technique of neural identification for the NRLN, which is at increased risk of injury during thyroid surgery.

STUDY DESIGN

Retrospective.

METHODS

A study of cases of the NRLN from consecutive thyroid surgeries with IONM was conducted. Preoperative and postoperative laryngoscopy was documented in all cases.

RESULTS

Ten right-sided nerves (0.6%) were identified as NRLN. One hundred percent of NRLNs had documented normal preoperative and postoperative laryngeal function. Distal and proximal vagal nerve stimulation points that allowed for the electrophysiologic prediction of a nonrecurrence in all patients were identified. Electrophysiological normative parameters of NRLN were compared to those of the normal right RLN and right vagus nerves.

CONCLUSION

Nonrecurrent laryngeal nerve is present in 0.6% of patients undergoing thyroid surgery. Intraoperative monitoring involving vagal stimulation at the defined distal and proximal points provides reliable electrophysiologic intraoperative verification of the presence of the NRLN. Three anatomical subtypes of right NRLN are noted that enable early identification of the NRLN. In conjunction with detailed knowledge of the NRLN anatomic pathways, they also may be helpful in preventing injury to the NRLN, which has been shown to be at higher risk during thyroid surgery. We provide an anatomic and electrophysiologic algorithm for reliable identification of the NRLN.

LEVEL OF EVIDENCE

4.

A new strategy for the surgical management of RLN infiltrated by well-differentiated thyroid carcinoma

Well-differentiated thyroid carcinoma (WDTC) represents the most common endocrine malignancy. Despite excellent prognoses exceeding 90% in 10-year follow-up, there are clinically controversial issues. One of these is extrathyroidal tumour extension invading recurrent laryngeal nerve (RLN). The spread outside of the thyroid parenchyma and invasion to the surrounding structures, classified as always T4a, are the most important negative prognostic factor for the WDTC. Conversely, resection of the RLN leads to vocal cord paralysis with hoarseness, possible swallowing problems, and finally decreased quality of life. We propose a new algorithm for intraoperative management based on the MACIS classification, which would allow swift status evaluation pre/intraoperatively and consider a possibility to preserve the infiltrated RLN without compromising an oncological radicality. In the case of a preoperative vocal cord paralysis (VCP) and confirmation of the invasive carcinoma, a resection of the RLN and the nerve graft reconstruction are indicated. Preoperatively, unaffected vocal cord movement and intraoperatively detected RLN infiltration by the invasive WDTC require an individual assessment of the oncological risk by the proposed algorithm. Preservation of the infiltrated RLN is oncologically acceptable only in specific groups of patients of a younger age with a minor size of primary tumour.