Identification Of Recurrent Laryngeal Nerve Research Articles

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

PurposeIntraoperative 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.MethodsA 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).ResultsThe 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).ConclusionsThere was a sharp decrease in the number of technical problems involving equipment setup from 2012 to 2014.

Vocal Fold Paralysis after Esophagectomy for Carcinoma.

(1) To recognize factors that contribute to vocal fold paralysis (VFP) after esophagectomy. (2) To describe the morbidity associated with VFP after esophagectomy. Retrospective cohort study. Tertiary care academic medical center. The medical records of 91 patients undergoing esophagectomy for malignancy were reviewed (2008-2014). Twenty-two patients with postoperative VFP were compared with 69 patients without VFP with regard to preoperative variables, surgical approach (transcervical vs other), and postoperative outcomes. A subset analysis of cervical approaches was performed, including those where an otolaryngologist assisted. There were no significant differences in preoperative variables between patients with and without VFP. Cervical approaches were associated with increased VFP (P < .0001). Recurrent laryngeal nerve (RLN) identification was associated with increased VFP (P = .0001). RLN dissection by head and neck surgeons was associated with decreased VFP (P = .0223). Patients with VFP had longer lengths of stay (P = .0078), higher rates of tracheotomy (P = .0439), and required more outpatient swallow evaluations (P = .0017). Mean time to diagnosis of VFP was 45.6 days (median, 7.5 days). Cervical approaches are associated with increased VFP in patients undergoing esophagectomy for malignancy. When cervical approaches and mobilization are required, the inclusion of an experienced cervical surgeon to identify the RLN may improve the rate of postoperative VFP. Patients with VFP after esophagectomy experience significantly more morbidity. Due to the potential delay in diagnosis and treatment of postoperative VFP, routine assessment of inpatient vocal fold function may be beneficial.

Effect of laryngotracheal topical anesthesia on recurrent laryngeal nerve monitoring during thyroid Surgery

Study ObjectiveIntraoperative neuromonitoring of the recurrent laryngeal nerve (RLN) is often used as an adjunct for RLN identification and preservation during thyroidectomies. Laryngotracheal anesthesia (LTA) with topical lidocaine reduces coughing upon emergence from anesthesia and in the immediate postoperative period; however, its use is prohibited with concerns that it could decrease the sensitivity of the intraoperative neuromonitoring. We hypothesize that there is no difference in measurements of nerve conduction made before and after LTA administration. DesignAn observational study in which all patients were subjected to LTA administration was conducted. Recurrent laryngeal nerve threshold currents were measured before and after the intervention. SettingTertiary medical center operating room. PatientsEighteen patients (total of 25 nerves at risk) with American Society of Anesthesiologists classes 1 to 3 undergoing thyroid surgery. InterventionsAfter the thyroid was removed and threshold currents at the RLN were obtained, LTA with endotracheal lidocaine was applied on the left and right side of the in situ endotracheal tube (2 cc of 4% lidocaine per side). Threshold currents were reassessed at 5 and 10 minutes after LTA administration. MeasurementsThreshold currents (minimum stimulus current applied to the RLN required to generate a discernible electromyographic response at the vocal cords) were recorded along the RLN for a baseline at 5 and 10 mm from the insertion point of the RLN into the larynx. Threshold currents were reassessed at the same 2 positions on the RLN at 5 and 10 minutes after LTA administration. Differences in mean values, between threshold currents recorded at the 3 different times, at 2 positions on the RLN, were used to compare effects of LTA on nerve conduction. Main ResultsThere were no statistically significant differences when comparing threshold currents before and after LTA administration. ConclusionsLaryngotracheal anesthesia had no significant effect on RLN nerve conduction in the period assessed.

Voice Changes after Late Recurrent Laryngeal Nerve Identification Thyroidectomy

To assess voice changes in patients after thyroidectomy where the recurrent laryngeal nerve (RLN) was found late in the thyroid dissection and where the RLN was not injured (late RLN identification technique). This study was conducted on 64 patients who underwent thyroidectomy by late RLN identification technique. Voice was assessed preoperatively, 1 week, 3 months, and 6 months after surgery using the voice assessment protocol and Voice Problem Self-Assessment Scale. The study group was divided into two subgroups (hemithyroidectomy: N = 13 and total thyroidectomy: N = 51). Voice assessments of both subgroups were then compared with a control group (N = 20) of patients who recently underwent extracervical surgeries. All voice analysis differences between the control group and the individual study subgroup were nonsignificant. Dysphonia in the study group was significantly worse at 1 week and 3 months postoperatively but became nonsignificant at 6 months postoperatively. The deviations from the preoperative acoustic analysis were significant only in the first week postoperative comparison for fundamental frequency, noise-to-harmonic ratio, and maximal phonation time and thereafter became nonsignificant. Significant Voice Problem Self-Assessment Scale mean score increase (worsening) was also detected only at first week postoperatively. Minimal voice changes were reported early after late RLN identification thyroidectomy in absence of RLN injury and disappeared gradually in a few months. Those changes are comparable with that of other extracervical surgeries, making thyroidectomy with late RLN identification a relatively safe technique as regard voice.

Loss of neuromonitoring signal during bilateral thyroidectomy: no systematic change in operative strategy according to a survey of the French Association of Endocrine Surgeons (AFCE).

BackgroundTotal thyroidectomy presents a risk of bilateral vocal cord paralysis, which can lead to compromised airway. Visual Recurrent Laryngeal Nerve (RLN) identification significantly decreases this risk of RLN lesion. Yet, an anatomically intact nerve is not always functional. Intraoperative neuromonitoring (IONM) allows to test in real time the function of the RLN. In case of loss of signal (LOS) on the first operated side, some authors recommend to stop the intervention. The purpose of this study was to characterize the operative strategy of the French-speaking surgeons in case of LOS on the first side in planned bilateral thyroidectomies.MethodsAn online questionnaire was sent to the surgeons of the French Association of Endocrine Surgeons (AFCE).ResultsWe collected 69 responses (response rate: 42 %). Forty-six surgeons (66 %) used IONM. After a signal loss, 22 % (N = 10) stopped the operation in all cases, 24 % (N = 11) continued the operation in case of malignant disease and stopped in cases of benign disease, and 54 % (N = 25) continued the operation contralaterally.ConclusionsThe majority of surgeons continued the operation contralaterally as originally planned despite a loss of IONM signal at the end of the first side.

Minilaparoscopy-Assisted Hemithyroidectomy and Central Neck Dissection (Level VI) Using Bilateral Breast Approach

Introduction: Minilaparoscopy-assisted thyroidectomy using the bilateral breast approach is a technique for thyroidectomy in patients with thyroid disease. This technique can promote the effect of cosmetology in thyroid surgery. In this video, we outline the instrument, operating room setup, and trocar position, present a minilaparoscopy-assisted hemithyroidectomy and central neck dissection (level VI), and demonstrate recurrent laryngeal nerve and two parathyroids in operation. Materials and Methods: In August 2014, we operated on a 35-year-old female patient. The patient underwent fine-needle aspiration cytology, diagnosed as left papillary thyroid carcinoma. After CT scan and ultrasonic inspection preoperation, the clinical staging is cT1aN0M0 staging I. According to the Chinese thyroid nodule and thyroid cancer guideline,1 we decided to perform left hemithyroidectomy and central neck dissection (level VI) using a bilateral areolar approach. 0.2 mL carbon nanoparticle suspension was injected to the thyroid gland with ultrasonic guidance 2 weeks before operation. The approach starts with the thyroid isthmus liberation that is dissected free from the anterior part of the trachea and transected. Then, the superior pole vessels are divided. The superior pole is then mobilized laterally and the recurrent laryngeal nerve is searched for at the inferior pole. The dissection continues between the nerve and the posterior part of the thyroid progressively, from bottom to top. After the recurrent nerve dissection, the gland can usually be extracted without difficulty, dividing the last vessels in berry ligament holding the gland. While in central neck dissection, first, we confirmed the lateral boundaries of central compartment and identified the recurrent laryngeal nerve. Then completed the central neck dissection. Finally, we present the superior thyroid artery, recurrent laryngeal nerve, and parathyroids after dissection, cleaning up, and closure. Results: The patient who was operated with this technique had a duration of hospitalization of 3 days without any postoperative complication. Carbon nanoparticle suspension is an ideal lymphatic tracer for endoscopic thyroidectomy and central neck dissection, although there is some leakage of carbon nanoparticle suspension in this patient. It does not affect the identification and preservation of recurrent laryngeal nerve and parathyroids. Conclusions: We prefer to operate cN0 thyroid cancer using this technique because it allows us to better identify and preserve the recurrent laryngeal nerve and parathyroids and same boundaries in central neck dissection. Moreover, it brings better cosmetic results for young patients. No competing financial interests exist. Runtime of video: 9 mins 57 secs

A novel surgical management of hypopharyngeal branchial anomalies

ObjectiveTo review our experience treating hypopharyngeal branchial anomalies utilizing an open transcervical approach that: (1) includes recurrent laryngeal nerve (RLN) monitoring and identification if needed; (2) resection of tract if present; and (3) a superiorly based sternothyroid muscle flap for closure. MethodsA retrospective chart review was performed to identify all patients at a tertiary level children's hospital with branchial anomalies from 2005 to 2014. The clinical presentation, evaluation, treatment and outcome were analyzed for those patients with hypopharyngeal branchial anomalies. ResultsForty-seven patients who underwent excision of branchial anomalies with a known origin were identified. Thirteen patients had hypopharyngeal branchial anomalies. Six of these patients were treated by the authors of this study and are the focus of this analysis. All six underwent an open transcervical procedure with a sternothyroid muscle flap closure of a piriform sinus opening over a nine year period. Definitive surgery included a microlaryngoscopy and an open transcervical approach to close a fistula between the piriform sinus and neck with recurrent laryngeal nerve monitoring or dissection. A superiorly based sternothyroid muscle flap was used to close the sinus opening. There were no recurrences, recurrent laryngeal nerve injuries or other complications from these procedures. ConclusionsThis study supports complete surgical extirpation of the fistula tract using an open cervical approach, recurrent laryngeal nerve monitoring or identification, and rotational muscle flap closure to treat patients with hypopharyngeal branchial anomalies.

Recurrent Laryngeal Nerve Identification During Thyroidectomy

Recurrent Laryngeal Nerve Identification During Thyroidectomy

Usefulness of neuromonitoring in thyroid surgery.

One of the most important complications during thyroid surgery is injury to the recurrent laryngeal nerve (RLN) which leads to dysfunction and palsy of the vocal folds. Adequate knowledge about the location of the RLN supported by neuromonitoring can help the operating surgeon to prevent this complication. Visualization of the nerve alone seems not enough. An estimation of the function of the RLN is very important. Recently, the use of neuromonitoring has been increasingly employed to predict and document nerve function at the end of thyroidectomy. The aim of the study was to verify the usefulness of neuromonitoring in identifying the recurrent laryngeal nerve and to predict postoperative outcome in patients undergoing thyroid surgery for different indications. Between March 2009 and October 2010, 91 patients (26 men, 65 women; mean age 53 (range 26-83) underwent thyroidectomy. Intraoperative neuromonitoring (IONM) was registered for 91 patients. Eighty-four total thyroidectomies and seven lobectomies were performed with IONM. Eight unilateral postoperative transient paresis were identified without any permanent paralysis. Intraoperative neuromonitoring has an excellent specificity and negative predictive value in which an unchanged positive signal is highly predictive of intact nerve function. Intraoperative neuromonitoring during thyroid surgery is a reliable tool for early recurrent laryngeal nerve localization and identification, certainly in complicated thyroid operations. The probability is high for correctly predicting an intact postoperative nerve function by neuromonitoring.

A retrospective case-controlled study of video-assisted versus open minimally invasive parathyroidectomy.

IntroductionMinimally invasive parathyroidectomy (MIP) with intraoperative parathyroid hormone assay (IOPTH) has successfully replaced conventional neck exploration in most patients with primary hyperparathyroidism (pHPT) and preoperatively localized parathyroid adenoma.AimTo compare outcomes of video-assisted MIP (MIVAP) to open MIP (OMIP).Material and methodsA retrospective case-controlled study of 455 patients with sporadic pHPT undergoing MIP with IOPTH at our institution in 2003–2012 was undertaken. The primary outcome measure was postoperative pain. Secondary outcome measures were: duration of surgery, recurrent laryngeal nerve (RLN) identification rate, conversion rate, length of hospital stay, cure rate, patients’ satisfaction with cosmetic outcome, morbidity, costs, and diagnostic accuracy of IOPTH.ResultsOf 455 patients with pHPT and a solitary parathyroid adenoma on preoperative imaging, 151 underwent MIVAP and 304 had OMIP. The following outcomes were favourable for MIVAP vs. OMIP: lower pain intensity during 24 h postoperatively (p < 0.001), lower analgesia request rate (p < 0.001), lower analgesics consumption (p < 0.001), higher recurrent laryngeal nerve identification rate (p < 0.001), shorter scar length (p < 0.001), and better cosmetic satisfaction at 1 month (p = 0.013) and at 6 months (p = 0.024) after surgery. However, MIVAP vs. OMIP had longer duration of surgery (p < 0.001), and was more expensive (p < 0.001). No differences were noted in the conversion rate, length of hospital stay, and morbidity.ConclusionsBoth MIVAP and OMIP approaches were equally safe and effective. However, the outcomes of MIVAP operations were superior to OMIP in terms of lesser postoperative pain, lower analgesics consumption, and better cosmetic satisfaction resulting from a smaller scar.

Audit of Patients Undergoing Thyroid Surgery in an Attempt to Improve the Standard of Care

Objectives: Improve the standard of care for patients undergoing thyroid surgery. Recognized complications include hypocalcemia and recurrent laryngeal nerve (RLN) damage. We aimed to review our practice and improve it by adhering to the criteria set out by the National Institute of Clinical Excellence (NICE). Methods: Retrospective audit looking at patients undergoing thyroid surgery over a 6-month period (09/2012). Pro forma methods were used to establish the adequacy of documentation including the use of nerve monitoring equipment, identification and stimulation of the RLN, and the recording of pre- and postoperative vocal cord checks (n = 18). Retrospective re-audit after recommendations to complete the loop (n = 8) over a 4-month period. Results: The first part of the audit cycle identified haphazard management of calcium levels in the postoperative period, incomplete documentation of vocal cord checks, and RLN identification and testing during surgery. Recommendations and guidance to staff, as well as a revised protocol on calcium management, resulted in improved care overall following re-audit. In part 2 of the audit cycle; only 1 patient became hypocalcemic in the postoperative period and was managed successfully following the protocol. RLN detection, testing, and monitoring were documented in all patients. The 2nd loop showed that all patients were receiving documented RLN identification and stimulation intraoperatively; all patients had documented pre- and postoperative cord checks and use of a nerve monitor (n=10). Conclusions: The audit shows we were able to meet the criteria set out by NICE.

A rapid and accurate technique for the identification of the recurrent laryngeal nerve.

We studied the anatomic relationship between the recurrent laryngeal nerve (RLN) and the third tracheal ring, which was very important for rapid identification of RLN in our hands. This study was initially performed using 8 fresh cadavers (4 female and 4 male). The transverse nerve location from the third trachea and the depth from its anterior surface were measured. We further observed the topography of RLN in relation to the trachea in 60 patients, between November 2008 and January 2011, at the Tri-Service General Hospital and Buddhist Tzu Chi General Hospital, Taipei Branch, Taiwan, with 46 lobo-isthmectomies and 14 total thyroidectomies. The time spent in identifying the RLN was also recorded. Among cadaver groups, the transverse distance (width) and the vertical distance (depth) averaged 3.3 and 17.6 mm, respectively. Among the clinical cases, the width and depth averaged 4.4 and 14.6 mm, respectively. The depth measured in males was significantly deeper than that in females (22.3 vs 13.2 mm) (P < .05). The time spent in identifying the RLN after starting dissection in the RLN triangle was not statistically significantly different between the cadaver group and the clinical group (10.6 ± 5.7 seconds and 15.5 ± 17.7 seconds, respectively; P > .05). The median time was 9 and 10 seconds, respectively. There was no statistically significant side-to-side difference in terms of the time spent in searching for the RLN. Using the third ring as guidance, our inferior-superior technique offers an extra benefit in identifying the RLN safely and quickly, as compared to the conventional inferior approach.

The experience of access application to recurrent laryngeal nerve and parathyroid glands as the way of the postoperative complications prevention in case of video-assisted surgery

Aim. To justify the application of surgical access to thyroid and parathyroid glands by means of videoendoscopic equipment. Methods. 14 video-assisted surgeries on thyroid and parathyroid glands were performed during the period of 2011-2014 using low-invasive midline cervical access by means of videoendoscopic equipment. Results. The surgery was carried out with a skin access of less than 3 cm, the section was made 1.5-2 cm above than jugular notch. Tissue dissection was performed by means of «channel» formation with mobilization of tissues while looking for recurrent laryngeal nerve and parathyroid glands up to allocation of the superior pole of a thyroid gland lobe under the laparoscopic control. In case of parathyroidectomy due to adenoma special attention was paid to presurgical topical diagnostics which included neck organs ultrasound examination with the use of expert class equipment as well as thyroid and parathyroid glands scintigraphy. Intrasurgical ultrasound examination of the area of surgery to specify the pathologically changed parathyroid gland location was performed in some cases. Jugular notch of sternum, lower pole of thyroid gland, lateral surface of trachea, tracheo-oesophageal groove, and inferior thyroid artery were used as reference points for identification of recurrent laryngeal nerve and parathyroid glands while using video equipment. As a rule, the recurrent laryngeal nerve was located behind and below the parathyroid glands. The distance from a skin section to a recurrent laryngeal nerve and lower parathyroid glands was 3.6 and 3.1 cm respectively. Conclusion. Use of video endoscopic equipment allows to reduce traumatic surgeries on neck organs and promotes the better visualization of anatomical structures in an area of surgery.

Evaluation of the efficacy of recurrent laryngeal nerve identification utilizing the Zuckerkandl tubercle

Abstract Recurrent laryngeal nerve identification is an essential step in thyroid surgery for preserving the patients’ voice and thus their quality of life. Methods of dissection and identification are adopted according to the surgeon’s preference. The aim of the study was to demonstrate the efficacy of recurrent laryngeal nerve identification using the Zuckerkandl tubercle as an anatomical landmark in comparison with the usual inferosuperior dissection of the tracheoesophageal groove. Four-hundred patients undergoing thyroidectomy were enrolled in a prospective comparative study. They were divided into two equal groups, each group being subjected to a specific technique. There was a nonsignificant statistical difference between the two techniques, thus validating the efficacy of Zuckerkandl tubercle as an anatomical landmark for identification of the recurrent laryngeal nerve. Ib.

Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy

BackgroundThe role of intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) during thyroid surgery is still debatable. The aim of this meta-analysis was to evaluate the potential improvement of IONM versus RLN visualization alone (VA) in reducing the incidence of vocal cord palsy. MethodsA literature search for studies comparing IONM versus VA during thyroidectomy was performed. Studies were reviewed for primary outcome measures: overall, transient, and permanent RLN palsy per nerve and per patients at risk; and for secondary outcome measures: operative time; overall, transient and permanent RLN palsy per nerve at low and high risk; and the results regarding assistance in RLN identification before visualization. ResultsTwenty studies comparing thyroidectomy with and without IONM were reviewed: three prospective, randomized trials, seven prospective trials, and ten retrospective, observational studies. Overall, 23,512 patients were included, with thyroidectomy performed using IONM compared with thyroidectomy by VA. The total number of nerves at risk was 35,513, with 24,038 nerves (67.7%) in the IONM group, compared with 11,475 nerves (32.3%) in the VA group. The rates of overall RLN palsy per nerve at risk were 3.47% in the IONM group and 3.67% in the VA group. The rates of transient RLN palsy per nerve at risk were 2.62% in the IONM group and 2.72% in the VA group. The rates of permanent RLN palsy per nerve at risk were 0.79% in the IONM group and 0.92% and in the VA group. None of these differences were statistically significant, and no other differences were found. ConclusionsThe current review with meta-analysis showed no statistically significant difference in the incidence of RLN palsy when using IONM versus VA during thyroidectomy. However, these results must be approached with caution, as they were mainly based on data coming from non–randomized observational studies. Further studies including high-quality multicenter, prospective, randomized trials based on strict criteria of standardization and subsequent clustered meta-analysis are required to verify the outcomes of interest.

Results of Intraoperative Neuromonitoring in Thyroid Surgery and Preoperative Vocal Cord Paralysis

Systematic studies of intermittent intraoperative neuromonitoring (IONM) have shown that IONM enhances recurrent laryngeal nerve (RLN) identification via functional assessment, but does not significantly reduce rates of vocal cord (VC) paralysis (VCP). The reliability of functional nerve assessment depends on the preoperative integrity of VC mobility. The present study was therefore performed to analyze the validity of IONM in patients with pre-existing VC paralysis. Of 8,128 patients, 285 (3.5%) with preoperative VCP underwent thyroid surgery using standardized IONM of the RLN and vagus nerves (VNs). VC function was assessed by pre- and postoperative direct videolaryngoscopy. Quantitative parameters of IONM in patients with VCP were compared with IONM in patients with intact VC function. Clinical symptoms and surgical outcomes of patients with pre-existing VCP were analyzed. A total of 244 patients revealed negative, and 41 revealed positive IONM on the side of the VCP. VCP with positive IONM revealed significantly lower amplitudes of VN and RLN than intact VN (p=0.010) and RLN (p=0.011). Symptoms of patients with VCP included hoarseness (25%), dyspnea (29%), stridor (13%), and dysphagia (13%); 13% were asymptomatic. New VCP occurred in five patients, ten needed tracheostomy for various reasons, and one patient died. Patients with pre-existing VCP revealed significantly reduced amplitude of ipsilateral VN and RLN, indicating retained nerve conductivity despite VC immobility. Preoperative laryngoscopy is therefore indispensable for reliable IONM and risk assessment, even in patients without voice abnormalities.

The long-term impact of routine intraoperative nerve monitoring during thyroid and parathyroid surgery

Despite widespread use of intraoperative nerve monitoring (IONM) as an adjunct to visual identification of the recurrent laryngeal nerve (RLN), published studies have shown little or no benefit. No long-term studies exist detailing the effect of experience gained from IONM on the rate of RLN injury. The aim of this study was to evaluate the impact of IONM feedback on surgical outcomes over time at a single institution. We conducted retrospective analysis of prospectively gathered data for 1,936 patients including 3,435 nerves at risk between March 2004 and September 2011. Each RLN was analyzed for the specific, unilateral operative procedure that placed the nerve at risk of injury. The primary outcome measures included temporary vocal cord palsy and permanent vocal cord paralysis or paresis as determined by intraoperative loss of RLN function and postoperative laryngoscopy. Additional measures included instances where IONM assisted the surgeon's localization of the RLN. Of the 3,435 nerves at risk, 105 (3.06%) were injured, 4 had permanent paralysis (0.12%), and 7 had paresis (0.20%). Over time, a decrease in RLN injury was seen per successive operative year for thyroid lobectomy with paratracheal lymph node dissection with or without parathyroidectomy (odds ratio, 0.98; 95% confidence interval, 0.97-1.00; P = .04); the rate of nerve injury stabilized after 20 months of continued use of nerve monitoring. IONM particularly assisted the surgeon with identification of 108 nerves at risk (3.14%) with aberrant anatomy, and with identification of 236 nerves at risk (6.87%) during difficult dissections. With experience, routine use of IONM during thyroid and parathyroid operations significantly decreased the incidence of injury to the RLN for thyroid lobectomy with paratracheal lymph node dissection and provided useful assistance with RLN identification for 10% of nerves at risk.

Nerve monitoring in the hands of less experienced surgeons.

To the Editor, We read with interest the paper titled “Is Nerve Monitoring Required in Total Thyroidectomy? Cerrahpasa Experience” by Teksoz et al. in the Indian Journal of Surgery [1]. In their study, 322 recurrent laryngeal nerves (RLN) under risk were evaluated. Patients who underwent total thyroidectomy including visual identification of RLN combined with intraoperative neurophysiological monitoring (IONM) were identified as group 1(n = 162), whereas those who underwent total thyroidectomy without RLN identification were identified as group 2 (n = 160). As the results of their study, they clinically supposed that “nerve monitoring does not provide any contribution to an experienced surgeon; however, it might be used to assist less experienced surgeons with anatomical identification”. In our surgery clinic, IONM is a preferred and well-known procedure in the treatment of thyroid diseases. Based on our experience, this procedure has some limitations and should not be performed by less experienced surgeons. It may be dangerous in the hands of less experienced surgeons. We would like to express our opinion, based on some important questions: First, the neuromonitoring system has special pitfalls, which have to be described. The amplitude (number of oscillations) of the wave, which was evoked by stimulation of the RLN, is typically a biphasic waveform which represents the summated motor action. During the thyroid surgery, the amplitude may be affected negatively by several factors such as inadequate probe–nerve contact, fluid or blood in the place of stimulation, covering of the nerve by the fascia, the environmental temperature and endotracheal tube electrode surface position [2]. Second, intermittent RLN monitoring alone was shown to be not accurate enough in predicting RLN injury because lesions at the RLN can be proximal from the stimulation point. The adoption of the IONM technique is precluded by a steep learning curve. Device malfunction may result in unsuccessful monitoring, which could potentially give rise to misleading information and, hence, increase the risk of RLN injury [3]. A false result such as “not nerve” because of the above-mentioned reasons may be very frustrating and dangerous especially for a less experienced surgeon. The surgeon may cut the nerve by misleading information. The initial rule of neuromonitoring is visualisation of the nerve. How could a surgeon with less experience in anatomical identification be adept in neuromonitoring? Third, in group 2, the authors did not identify the RLN. Additionally, they did not find a statistically significant difference between groups for RLN paralysis. On the other hand, in the literature, routine visualisation of the RLN has been suggested in thyroid surgery. Regarding the identification of RLN and its preservation, it is now believed that the “nerve not seen is damaged” rather than “seen is damaged” as was earlier believed. In their daily surgical practice, do the authors really not identify RLN, or do they perform routine RLN dissection? Finally, we believe that the main factors influencing a reduction of RLN injury rates are meticulous dissection technique and respect of the gold standard that includes routine visualisation of the RLN.

Signalveränderungen des kontinuierlichen intraoperativen Neuromonitorings bei Schilddrüseneingriffen mit postoperativen Rekurrensparesen

Continuous intraoperative neuro-monitoring (kontIONM) and the provision of relevant information such as moment, origin and prognosis of nerve function impairment during thyroid resection have been tested. Between 2009 and 2011, 667 patients were operated for thyroid pathology by applying kontIONM (tube electrode, vagal probe V3, ISIS; Fa. Inomed, Emmendingen, Germany). Vocal cord function was examined laryngoscopically on the 2nd postoperative day. Palsies were diagnosed in 34 patients. Complete kontIONM signals were filed during the operation. Loss of signal (LOS), defined as amplitude reduction < 100 µV, and signal delay > 10% were attributed to thyroid dissection. A LOS of 17.6% (6/34) developed already at the moment of thyroid lobe luxation, that is, prior to a dissection for recurrent laryngeal nerve (NLR) identification. An LOS of 67.6% (23/34) appeared during NLR preparation in the vicinity of the Berry ligament. Thus, 85.3% of all vocal cord palsies were recognised intraoperatively. For four patients signal delay > 10% could be observed in the analysis of the postoperative signal but not during the operation. One case was not associated with any of these signal changes. In the majority of cases, signal loss and reduction of amplitude < 100 µV are reliable parameters of post-operative vocal cord palsy. Traction and distension of the nerve seems to be the most important cause of nerve damage. An immediate revision of the last step of the surgical procedure, if required, is the essential advantage of this method to avoid irreversible nerve damage. For a minor part of the cases, vocal cord palsies are characterised intraoperatively by an extended delay of the signal.

Outcomes of Visual Identification and Protection of the Recurrent Laryngeal Nerve during Thyroid Surgery

Routine Identification of Recurrent Laryngeal Nerve during Thyroid and Parathyroid Surgery | Prevention of Recurrent Laryngeal Nerve Injury in Thyroid Surgery | Recurrent Laryngeal Nerve Injury in Thyroid Surgery