Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve During Thyroidectomy with Adhesive Skin Electrodes.

BACKGROUND: Alternative methods to overcome limitations of electromyogram (EMG) tube applied for intraoperative neuromonitoring (IONM) of recurrent laryngeal nerve (RLN) during thyroidectomy have been introduced. In this study, we evaluated the feasibility of adhesive skin electrodes for IONM of RLN in patients who underwent thyroidectomy. METHODS: A total of 39 nerves at risk were prospectively enrolled in this study. Twenty-five patients with papillary thyroid carcinoma, 3 patients with follicular neoplasm, and 2 patients with Graves' disease underwent thyroidectomy. All patients were intubated with EMG tube, and two disposable pre-gelled surface electrodes were attached to skin at both upper margins of thyroid cartilage. We followed the standard procedure of IONM, and the latency (msec) and amplitude (µV) of each signal were recorded prospectively. RESULTS: Intraoperative neuromonitoring using skin adhesive electrodes was successful in all nerves at risk. Amplitudes of the signals in IONM were significantly lower compared to those from EMG tube at each step of IONM, while no significant difference was identified in latency between two methods. Four nerves at risk (10.3%) showed loss of signal (<100 µV) during the steps of IONM from EMG tube, while all nerves at risk from adhesive skin electrodes showed acceptable biphasic EMG signal. CONCLUSION: We verified the usefulness of adhesive skin electrodes for IONM of RLN during thyroidectomy. Although lower amplitude remains the major limitation of this technique, adhesive skin electrodes may be considered an alternative method for IONM during thyroidectomy.

Lenvatinib complementary with radioiodine therapy for patients with advanced differentiated thyroid carcinoma: case reports and literature review.

BACKGROUND: The prognosis for patients with advanced differentiated thyroid carcinoma (ADTC) with disseminated distant metastases is very poor. Tyrosine kinase inhibitors targeting tumor angiogenesis have been shown to improve progression-free survival in patients with advanced thyroid carcinoma and progressive radioiodine-refractory thyroid carcinoma. Tyrosine kinase inhibitor has been reported as a successful neoadjuvant for total thyroidectomy to reduce tumor burden. However, the special indications for prompt treatment with lenvatinib as a rescue therapy to reduce tumor burden and prolong a durable response to radioiodine therapy have not been explored. CASE PRESENTATION: Here, we present two ADTC cases with distant metastases who were effectively treated by total thyroidectomy combined with lenvatinib to prolong a durable response to radioiodine therapy. Case 1 was a 66-year-old male diagnosed with ADTC and disseminated brain, lung, and bone metastases. Lenvatinib was initiated via compassionate access because of rapidly progressive tumor growth even after second doses of radioiodine therapy and external beam radiation therapy for his brain metastases. The result was a durable response to lenvatinib, slowing progressive tumor growth for 3 years and allowing a third course of radioiodine therapy to treat the bone metastases. Case 2 was a 45-year-old male diagnosed with ADTC and diffuse disseminated lung metastases. Respiratory failure ensued after total thyroidectomy, requiring mandatory support by respirator. Lenvatinib was started as a rescue therapy to reduce tumor burden rapidly. The patient was successfully weaned off the respirator only 1 week after using lenvatinib. The patient was then maintained on a low dose of lenvatinib, allowing three subsequent courses of radioiodine therapy. Currently, his lung metastasis remains well controlled with decreased lung infiltrating nodules and the patient can tolerate exercise well. CONCLUSION: Our case experience indicated that lenvatinib has significant value as salvage therapy, reducing tumor burden, producing a durable response and maintaining quality of life. For ADTC patients with progressive life-threatening metastases, our experience suggests that lenvatinib treatment can be used as an urgent rescue therapy as well as a complement to radioiodine therapy to improve tumor eradication.

Gastric acid secretion and gastrin release during continuous vagal neuromonitoring in thyroid surgery.

PURPOSE: The vagus nerve (VN) has essential regulatory roles in the gastric acid secretion and gastrin release. Continuous intraoperative neuromonitoring (CIONM) via VN stimulation is a promising technique in thyroid surgery because it potentially avoids injury to the recurrent laryngeal nerve. However, no studies have investigated changes in gastric acid secretion and gastrin release during CIONM. METHOD: This prospective study of 58 thyroid surgery patients compared gastric acid and serum gastrin at five time points: (1) before skin incision, (2) after baseline calibration of CIONM probe, (3) +20 min from baseline, (4) before probe removal, and (5) after extubation. Patients were excluded if they had any history of using tobacco, acid suppression medications, or drugs that affect gastric motility. Patients were also excluded if they had any history of gastroesophageal reflux symptoms, gastroesophageal reflux disease, peptic ulcer disease, helicobacter pylori infection, or chronic kidney disease. RESULTS: Non significant differences in mean gastric pH values were observed at all time points, i.e., (1) before skin incision (2.2 ± 0.2; p = 0.50), (2) after baseline calibration of CIONM probe (2.0 ± 0.8; p = 0.62), (3) +20 min from baseline (2.5 ± 0.5; p = 0.24), (4) before probe removal (2.9 ± 0.9; p = 0.52), and (5) after extubation (2.6 ± 1.0; p = 0.60). Comparisons of pH monitoring parameters revealed no significant differences in age, gender, side of CIONM (left vs. right), sequence of CIONM, or duration of CIONM. Gastrin values were normal in sequential determinations and did not significantly differ at any time points. CONCLUSIONS: CIONM performed via VN stimulation during total thyroidectomy in healthy patients does not influence gastrin secretion and gastric pH.

Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy-evaluation and outcome.

PURPOSE: During monitored thyroidectomy, a partially or completely disrupted point of nerve conduction on the exposed recurrent laryngeal nerve (RLN) indicates true electrophysiologic nerve injury. Complete loss of signal (LOS; absolute threshold value <100 µV) at the end of operation often indicates a postoperative vocal cord (VC) palsy. However, the evaluation for the injured RLN with incomplete LOS and its functional outcome has not been well described. METHODS: Three hundred twenty-three patients with 522 RLNs at risk who underwent standardized monitored thyroidectomy were enrolled. The RLN was routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends of exposure after thyroid resection to determine if there was an injured point on the RLN. Pre- and postoperative VC function was routinely examined. RESULTS: Twenty-nine RLNs (5.6 %) were detected with an injury point. Five nerves had complete LOS and other 24 nerves had incomplete LOS where the R2p/R2d reduction (% of amplitude reduction compared with proximal to distal RLN stimulation) ranged from 22 to 79 %. Postoperative temporary VC palsy was noted in those five RLNs with complete LOS (final vagal signal, V2 < 100 µV) and four RLNs with incomplete LOS (R2p/R2d reduction 62-79 %; V2 181-490 µV). In the remaining 20 nerves with R2p/R2d reduction ≤53 % (V2 373-1623 µV), all showed normal VC mobility. Overall, false negative results were found in two RLNs (0.4 %) featuring unchanged V2 and R2p/R2d but developed VC palsy. CONCLUSIONS: Testing and comparing the R2p/R2d signal is a simple and useful procedure to evaluate RLN injury after its dissection and predict functional outcome. When the relative threshold value R2p/R2d reduction reaches over 60 %, surgeon should consider the possibility of postoperative VC palsy.

Severity of Recurrent Laryngeal Nerve Injuries in Thyroid Surgery.

BACKGROUND: Few studies in the literature have reported recovery data for different types of recurrent laryngeal nerve injuries (RLNIs). This study is the first attempt to classify RLNIs and rank them by severity. METHODS: This prospective clinical study analyzed 281 RLNIs in which a true loss of signal was identified by intraoperative neuromonitoring (IONM), and vocal cord palsy (VCP) was confirmed by a postoperative laryngoscope. For each injury type, the prevalence of VCP, the time of VCP recovery, and physical changes on nerves were analyzed. Additionally, different RLNI types were experimentally induced in a porcine model to compare morphological change. RESULTS: The overall VCP rate in at-risk patients/nerves was 8.9/4.6 %, respectively. The distribution of RLNI types, in order of frequency, was traction (71 %), thermal (17 %), compression (4.2 %), clamping (3.4 %), ligature entrapment (1.6 %), suction (1.4 %), and nerve transection (1.4 %). Complete recovery from VCP was documented in 91 % of RLNIs. Recovery time was significantly faster in the traction group compared to the other groups (p < 0.001). The rates of temporary and permanent VCP were 98.6 and 1.4 % for traction lesion, 72 and 28 % for thermal injury, 100 and 0 % for compression injury, 50 and 50 % for clamping injury, 100 and 0 % for ligature entrapment, 100 and 0 % for suction injury, and 0 and 100 % for nerve transection, respectively. Physical changes were noted in 14 % of RLNIs in which 56 % of VCP was permanent. However, among the remaining 86 % IONM-detectable RLNIs without physical changes, only 1.2 % of VCP was permanent. A porcine model of traction lesion showed only distorted outer nerve structure, whereas the thermal lesion showed severe damage in the inner endoneurium. CONCLUSIONS: Different RNLIs induce different morphological alterations and have different recovery outcomes. Permanent VCP is rare in lesions that are visually undetectable but detectable by IONM. By enabling early detection of RLNI and prediction of outcome, IONM can help clinicians plan intra- and postoperative treatment.

Prospective validation study of Cernea classification for predicting EMG alterations of the external branch of the superior laryngeal nerve.

PURPOSES: Cernea classification is applied to describe the external branch of the superior laryngeal nerve (EBSLN). Using intraoperative neural monitoring we evaluated whether or not this classification is useful for predicting which EBSLN subtype has an increased risk of injury. METHODS: An analysis of 400 EBSLN. The identification of EBSLN was achieved with both cricothyroid muscle twitch and the glottis evoked electromyography response. We defined S1 initial EBSLN stimulation at identification and S2 final nerve stimulation achieved in the most cranial aspect of the nerve exposed above the area of surgical dissection after superior artery ligation. RESULTS: The mean S1 amplitude acquired was 259+/67 (180-421), 321 +/79 (192-391), 371 +/38 (200-551) µV, respectively, for type 1, 2A, 2B (p = 0.08). The S1 and S2 amplitudes were similar in type 1 (p = 0.3). The S1 and S2 determinations changed significantly in type 2A and 2B (p = 0.04 and 0.03). EBSLN which demonstrated a >25 % decreased amplitude in S2 increased significantly from Type 1 (4.9 %) to Type 2A (11.2 %) and 2B (18 %) (p = 0.01). None of type 1, 2.8 % type 2A and 3 % type 2B showed a loss of EBSLN conductivity. The latency determinations did not vary significantly for any parameter compared. CONCLUSIONS: The Cernea classification was, therefore, found to predict the risk of EBSLN stress. We identified amplitude differences between S1 and S2 determinations in type 2A and 2B, thus confirming that surgical dissection in these subtypes is, therefore, extremely difficult to perform.

Continuous Intraoperative Neuromonitoring (C-IONM) Technique with the Automatic Periodic Stimulating (APS) Accessory for Conventional and Endoscopic Thyroid Surgery.

One of the most important trends in intraoperative neural monitoring (IONM) in thyroid surgery is currently the real-time monitoring of the vagus nerve (VN) in order to prevent recurrent laryngeal nerve (RLN) iatrogenic damages. Notably, continuous intraoperative neuromonitoring (C-IONM) seems to be superior to intermitted intraoperative neural monitoring (I-IONM) because it enhances standardization by permanent vagus nerve (VN) stimulation, and it provides entire and constant RLN function monitoring as the surgeon dissects and removes the thyroid gland. It also has to be highlighted that the surgical maneuvers for the automatic periodic stimulating (APS) placement must be accurate and standardized in order to avoid a potential iatrogenic morbidity on the VN function. We recommend the experienced surgeon be very careful in each step, with cautious dissection. With this review article we provide a comprehensive analyses of C-IONM technique with the APS accessory for conventional and endoscopic thyroid surgery.

Evidence-based Analysis on The Clinical Impact of Intraoperative Neuromonitoring in Thyroid Surgery: State of the Art and Future Perspectives.

Laryngeal nerve injuries are one the most critical complications during thyroid and parathyroid surgery. Iatrogenic damages to the recurrent laryngeal nerve (RLN) are relevant in terms of clinical implications, economic costs, and for malpractice litigation. In order to minimize potential neural damages, a standardized surgical technique is mandatory. Intraoperatory neuromonitoring (IONM) of the RLN is an important adjunct to the traditional approach and is a reliable tool for neural mapping and in dissection and prognostication of postoperative neural function 4. Because of this, most of the iatrogenic damages are not related to direct transection, but they are visually undetectable. Notwithstanding the increasing use of IONM at this stage, there is still the need for prospective, randomized, well-powered, and well-designed trials in order to further validate (via evidence-based data) the role of IONM in thyroid surgery. The aim of this review is to provide a critical analysis of the scientific evidences on the clinical impact of IONM in thyroid surgery showing the unsolved problems and the future challenges.

Apigenin induces apoptosis via tumor necrosis factor receptor- and Bcl-2-mediated pathway and enhances susceptibility of head and neck squamous cell carcinoma to 5-fluorouracil and cisplatin.

BACKGROUND: Apigenin, a natural plant flavone, may have chemopreventive and therapeutic potentials for anti-inflammatory, antioxidant, and anti-cancer. Nevertheless, the anti-tumor effect of apigenin on human head and neck squamous cell carcinoma (HNSCC) is not fully understood. METHODS: The antioxidant capacity and protective effects of apigenin against oxidative stress in murine normal embryonic liver BNLCL2 cells are examined. Cell viability, morphologic change, clonogenic survival, cell cycle distribution, reactive oxygen species (ROS) production, glutathione formation, and death receptors- and Bcl-2-mediated caspase pathways of HNSCC SCC25 cells and A431 cells with apigenin are investigated. RESULTS: Apigenin inhibits the growth of SCC25 and A431 cells and induces cell cycle arrest in the G2/M phase. Apigenin has an antioxidant capacity as well as the ability to inhibit lipid peroxidation. It protects BNLCL2 cells against oxidative damage, and is potentially able to prevent cancer. Apigenin increases intracellular ROS levels and reduces levels of glutathione; it also induces cell apoptosis via tumor necrosis factor receptor (TNF-R)-, TNF-related apoptosis-inducing ligand receptor (TRAIL-R)-, and Bcl-2-mediated caspase-dependent cell death pathways in SCC25 cells. The combination of apigenin with 5-fluorouracil (5-Fu) or cisplatin induces the dramatic death of SCC25 cells. CONCLUSIONS: Apigenin induces SCC25 cell apoptosis via the up-regulation of both TNF-R and TRAIL-R signaling pathways, and has a synergistic effect on the inhibition of cell proliferation in combination with 5-Fu or cisplatin. GENERAL SIGNIFICANCE: These analytical findings suggest that apigenin may be a good therapeutic agent against HNSCC cells.

Lingual leiomyomatous hamartoma with bifid tip and ankyloglossia in a patient without oral-facial-digital syndrome: a case report and literature review.

Here is a rare case of lingual leiomyomatous hamartoma (LLH) with bifid tongue tip and tongue-tie in a patient with non-oral-facial-digital syndrome (OFDS). A 29-year-old male consulted for a painless tumor over the midline of the tongue dorsum measuring 2 × 1.5 cm. The tumor was excised and the tongue-tie was corrected. Diagnosis of LLH was based on histo-pathologic and immuno-histochemical studies. The epidemiologic data and differential diagnosis of LLH, as well as related literature, are discussed. To date, only 14 cases of LLH have been reported in English literature. This may be the first reported case of LLH with bifid tip and ankyloglossia in a non-OFDS patient.

Antioxidant, anti-adipocyte differentiation, antitumor activity and anthelmintic activities against Anisakis simplex and Hymenolepis nana of yakuchinone A from Alpinia oxyphylla.

BACKGROUND: Alpinia oxyphylla is a common remedy in traditional Chinese medicine. Yakuchinone A is a major constituent of A. oxyphylla and exhibits anti-inflammatory, antitumor, antibacterial, and gastric protective activities. METHODS: Antioxidant and antitumor characteristics of yakuchinone A in skin cancer cells as well as novel mechanisms for the inhibition of adipocyte differentiation, cestocidal activities against Hymenolepis nana adults, and nematocidal activities against Anisakis simplex larvae are investigated. RESULTS: Yakuchinone A presents the ability of the removal of DPPH·and ABTS+ free radicals and inhibition of lipid peroxidation. Yakuchinone A suppresses intracellular lipid accumulation during adipocyte differentiation in 3 T3-L1 cells and the expressions of leptin and peroxisome proliferator-activated receptor γ (PPARγ). Yakuchinone A induces apoptosis and inhibits cell proliferation in skin cancer cells. The inhibition of cell growth by yakuchinone A is more significant for non-melanoma skin cancer (NMSC) cells than for melanoma (A375 and B16) and noncancerous (HaCaT and BNLCL2) cells. Treatment BCC cells with yakuchinone A shows down-regulation of Bcl-2, up-regulation of Bax, and an increase in cleavage poly (ADP-ribose) polymerase (PARP). This suggests that yakuchinone A induces BCC cells apoptosis through the Bcl-2-mediated signaling pathway. The anthelmintic activities of yakuchinone A for A. simplex are better than for H. nana. CONCLUSIONS: In this work, yakuchinone A exhibits antioxidative properties, anti-adipocyte differentiation, antitumor activity, and anthelmintic activities against A. simplex and H. nana.

Vagus nerve stimulation for standardized monitoring: technical notes for conventional and endoscopic thyroidectomy.

Standardization of the intraoperative neuromonitoring (IONM) technique is an essential aspect of modern monitored thyroid surgery. The standardized technique involves vagal nerve stimulation. VN stimulation is useful for technical problem solving, detecting non-recurrent laryngeal nerve (non-RLN), recognizing any recurrent laryngeal nerve (RLN) lesions, and precisely predicting RLN postoperative function. Herein, we present technical notes for the VN identification to achieve the critical view of safety of the VN stimulation with or without dissection.

Comparison of EMG amplitudes recorded by ipsilateral and contralateral electrodes placement during using trans-thyroid cartilage recording method in thyroid surgery.

Objectives: The feasibility and reliability of trans-thyroid cartilage EMG recording method (TCERM) during intraoperative monitoring (IONM) of the recurrent laryngeal nerve (RLN) in thyroid surgery have been established. This study compared two different recording electrode placements on the ipsi-lateral and contra-lateral lamina of the thyroid cartilage (TC). Methods: Fifty consecutive patients undergoing total thyroidectomy with 100 RLNs at risk were enrolled. Two paired subdermal needle electrodes were inserted into the subperichondrium of the bilateral TC lamina to record electromyography (EMG) signals. The channel leads from the TC electrodes were connected to the patient interface with two different modes. In A-mode, the electrode leads were placed ipsi-laterally, and channel 1 monitored the left RLN and channel 2 monitored the right RLN respectively. In B-mode, the electrode leads were placed contra-laterally, and channels 1 and 2 simultaneously monitored the same side of the RLN. The amplitudes of four EMG signals (V1-R1-R2-V2) recorded by A-mode and B-mode were compared. Results: All EMG amplitudes of V1-R1-R2-V2 signals recorded with B-mode were all above 500µV and significantly higher than those with A-mode (p<0.001). No false loss of signal, electrode dislodgement, or needle-related complications were noted during IONM. Postoperatively, all patients had symmetrical vocal cord movement. Lower EMG amplitudes were observed in older and male patients. Histopathology and laterality showed no significant differences in EMG amplitude. Conclusion: During using TCERM in thyroid surgery, the recording electrodes should be placed contra-laterally on the TC lamina. This approach ensures high and stable EMG signals, which are important for high-quality IONM of the RLN.

Surgical treatment for thyrotoxic hypokalemic periodic paralysis: case report.

Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare, potentially life-threatening endocrine emergency. It is characterized by recurrent muscle weakness and hypokalemia. Because many THPP patients do not have obvious symptoms and signs of hyperthyroidism, misdiagnosis may occur. The published studies revealed that definitive therapy for THPP is control of hyperthyroidism by medical therapy, radioactive iodine or surgery, but the long-term post-operative follow-up result was not observed. We reported two cases of medically refractory THPP with recurrent paralysis of extremities and hypokalemia, and both were combined with thyroid nodules. Both patients were treated with total thyroidectomy; the pathology revealed that one is Graves' disease with thyroid papillary carcinoma, and the other is adenomatous goiter with papillary hyperplasia. No episode of periodic paralysis was noted and laboratory evaluation revealed normal potassium level during the post-operative follow up. Our experience suggests that total thyroidectomy by experienced surgeon is an appropriate and definite treatment for medically refractory THPP, especially in cases combined with thyroid nodules.

Detecting and identifying nonrecurrent laryngeal nerve with the application of intraoperative neuromonitoring during thyroid and parathyroid operation.

PURPOSE: The nonrecurrent laryngeal nerve (NRLN) is a rare anatomical variant but associated with high risk of nerve injury during thyroid and parathyroid operations. Therefore, intraoperative detection and verification of NRLN are necessary. METHOD: A total of 390 consecutive patients who underwent thyroid and parathyroid operations (310 RLNs dissected on the right side and 293 nerves on the left side) were enrolled. Electrically evoked electromyography was recorded from the vocalis muscles via an endotracheal tube with glottis surface recording electrodes. At an early stage of operation, vagal nerve was routinely stimulated at the level of inferior thyroid pole to ensure normal path of RLN. If there is a negative response from lower position but positive response from upper vagal stimulation, it indicates the occurrence of a NRLN, and we localize its separation point and path. RESULTS: Four right NRLNs (1.3%) without preoperative recognition were successfully detected at an early stage of operation. Three patients were operated on for thyroid disease, one for parathyroid adenoma and all were associated with right aberrant subclavian artery. All NRLNs were localized and identified precisely with intraoperative neuromonitoring. Functional integrity of all nerves was confirmed by the intraoperative neuromonitoring and postoperative laryngeal examination. CONCLUSIONS: Vagal stimulation at the early stage of operation is a simple, useful, and reliable procedure to detect and identify the NRLN.

Necessity of Routinely Testing the Proximal and Distal Ends of Exposed Recurrent Laryngeal Nerve During Monitored Thyroidectomy.

Objectives: Intraoperative neuromonitoring (IONM) is a useful tool to evaluate the function of recurrent laryngeal nerve (RLN) in thyroid surgery. This study aimed to determine the necessity and value of routinely testing the proximal and distal ends of RLN. Methods: In total, 796 patients undergoing monitored thyroidectomies with standardized procedures were enrolled. All 1346 RLNs with visual integrity of anatomical continuity were routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends after complete RLN dissection. The EMG amplitudes between R2p and R2d signals were compared. If the amplitude of R2p/R2d ratio reduction (RPDR) was over 10% or loss of signal (LOS) occurred, the exposed RLN was mapped to identify the injured point. Pre- and post-operative vocal cord (VC) mobility was routinely examined with video-laryngofiberscope. Results: Nerve injuries were detected in 108 (8%) RLNs, including 94 nerves with incomplete LOS (RPDR between 13%-93%) and 14 nerves with complete LOS. The nerve injuries were caused by traction in 80 nerves, dissecting trauma in 23 nerves and lateral heat spread of energy-based devices in 5 nerves. Symmetric VC mobility was found in 72 nerves with RPDR ≤50%. The occurrence of abnormal VC mobility (weak or fixed) was 14%, 67%, 100%, and 100% among the different RPDR stratifications of 51%-60%, 61%-70%, 71%-80%, and 81-93%, respectively. Of the 14 nerves with complete LOS, all showed fixed VC mobility. Permanent VC palsy occurred in 2 nerves with thermal injury. Conclusion: Routinely testing the proximal and distal ends of exposed RLN helps detect unrecognized partial nerve injury, elucidate the injury mechanism and determine injury severity. The procedure provides accurate information for evaluating RLN function after nerve dissection and should be included in the standard IONM procedure.

A Surgeon-Centered Neuromuscular Block Protocol Improving Intraoperative Neuromonitoring Outcome of Thyroid Surgery.

Background: Neuromuscular blocking agents provide muscular relaxation for tracheal intubation and surgery. However, the degree of neuromuscular block may disturb neuromuscular transmission and lead to weak electromyography during intraoperative neuromonitoring. This study aimed to investigate a surgeon-friendly neuromuscular block degree titrated sugammadex protocol to maintain both intraoperative neuromonitoring quality and surgical relaxation during thyroid surgery. Methods: A total of 116 patients were enrolled into two groups and underwent elective thyroid surgery with intraoperative neuromonitoring. All patients followed a standardized intraoperative neuromonitoring protocol with continuous neuromuscular transmission monitoring and received 0.6 mg/kg rocuronium for tracheal intubation. Patients were allocated into two groups according to the degree of neuromuscular block when the anterior surface of the thyroid gland was exposed. The neuromuscular block degree was assessed by the train-of-four (TOF) count and ratio. Patients in group I received sugammadex 0.25 mg/kg for non-deep neuromuscular block degree (TOF count = 1~4). Patients in group II were administered sugammadex 0.5 mg/kg for deep neuromuscular block degree (TOF count = 0). The quality of the intraoperative neuromonitoring was measured using the V1 electromyography (EMG) amplitude. An amplitude less than 500 µV and greater than 500 µV was defined as weak and satisfactory, respectively. Results: The quality of the intraoperative neuromonitoring was not different between groups I and II (satisfactory/weak: 75/1 vs. 38/2, P = 0.14). The quality of surgical relaxation was acceptable after sugammadex injection and showed no difference between groups [55/76 (72.3%) in group I vs. 33/40 (82.5%) in group II, P = 0.23]. Conclusions: This surgeon-centered sugammadex protocol guided by neuromuscular block degree (0.5 mg/kg for deep block and 0.25 mg/kg for others) showed comparably high intraoperative neuromonitoring quality and adequate surgical relaxation. The results expanded the practicality of sugammadex for precise neuromuscular block management during monitored thyroidectomy.

Intraoperative EMG recovery patterns and outcomes after RLN traction-related amplitude decrease during monitored thyroidectomy.

Objectives: Traction injury is the most common type of recurrent laryngeal nerve (RLN) injury in thyroid surgery. Intraoperative neuromonitoring (IONM) facilitates early detection of adverse electromyography (EMG) effect, and this corrective maneuver can reduce severe and repeated nerve injury. This study aimed to evaluate intraoperative patterns and outcomes of EMG decrease and recovery by traction injury. Methods: 644 patients received nerve monitored thyroidectomy with 1142 RLNs at risk were enrolled. Intermittent IONM with stimulating dissecting instrument (real-time during surgical procedure) and trans-thyroid cartilage EMG recording method (without electrode malpositioning issue) were used for nerve stimulation and signal recording. When an EMG amplitude showed a decrease of >50% during RLN dissection, the surgical maneuver was paused immediately. Nerve dissection was restarted when the EMG amplitude was stable. Results: 44/1142 (3.9%) RLNs exhibited a >50% EMG amplitude decrease during RLN dissection and all (100%) showed gradual progressive amplitude recovery within a few minutes after releasing thyroid traction (10 recovered from LOS; 34 recovered from a 51-90% amplitude decrease). Three EMG recovery patterns were noted, A-complete EMG recovery (n=14, 32%); B-incomplete EMG recovery with an injury point (n=16, 36%); C-incomplete EMG recovery without an injury point (n=14, 32%). Patients with postoperative weak or fixed vocal cord mobility in A, B, and C were 0(0%), 7(44%), and 2(14%), respectively. Complete EMG recovery was found in 14 nerves, and incomplete recovery was found in another 30 nerves. Temporary vocal cord palsy was found in 6 nerves due to unavoidable repeated traction. Conclusion: Early detection of traction-related RLN amplitude decrease allows monitoring of intraoperative EMG signal recovery during thyroid surgery. Different recovery patterns show different vocal cord function outcomes. To elucidate the recovery patterns can assist surgeons in the intraoperative decision making and postoperative management.

Proposals for Standardization of Intraoperative Facial Nerve Monitoring during Parotid Surgery.

Intraoperative facial nerve monitoring (FNM) has been widely accepted as an adjunct during parotid surgery to facilitate identification of the facial nerve (FN) main trunk, dissection of FN branches, confirmation of FN function integrity, detection of FN injury and prognostication of facial expression after tumor resection. Although the use of FNM in parotidectomy is increasing, little uniformity exists in its application from the literature. Thus, not only are the results of many studies difficult to compare but the value of FNM technology is also limited. The article reviews the current literature and proposes our standardized FNM procedures during parotid surgery, such as standards in FNM setup, standards in general anesthesia, standards in FNM procedures and application of stimulus currents, interpretation of electrophysiologic signals and prediction of the facial expression outcome and pre-/post-operative assessment of facial expressions. We hope that the FNM standardized procedures will provide greater uniformity, improve the quality of applications and contribute to future research.

A comparison between cisatracurium and rocuronium-induced neuromuscular block on laryngeal electromyography recovery after neostigmine reversal in a porcine model.

Background: Inducing and reversing neuromuscular block is essential to a positive outcome of thyroid surgery, with intraoperative neuromonitoring (IONM) being used to decrease recurrent and superior laryngeal nerve injuries and improve vocal outcome. Neostigmine is a non-specific broad-spectrum and inexpensive reversal agent for neuromuscular blocking agents (NMBAs). The aim of this porcine study was to explore the effect of neostigmine on electromyography (EMG) signal recovery profile following the commonly used NMBAs, cisatracurium and rocuronium. Methods: Twelve piglets were allocated into two groups with six piglets in each group. When stable baseline EMG signals were obtained, a neuromuscular block was induced by intravenous cisatracurium 0.2 mg/kg (group C) or rocuronium 0.6 mg/kg (group R) for each piglet. We compared laryngeal EMG tracing with spontaneous recovery (control) and neostigmine (0.04 mg/kg) reversal for each group. The time course of real-time laryngeal EMG signals was observed for 30 min from NMBA injection. Effects of neostigmine on EMG signal were assessed at 50% EMG recovery and by the maximum neuromuscular block recovery degree from the baseline value. Results: Neostigmine shortened the recovery time to 50% EMG amplitude in both group C (16.5 [2.5] vs. 29.0 [2.0] min, P<0.01) and group R (16.5[2.5] vs. 26.5 [1.5] min, P<0.05) compared to spontaneous recovery, respectively. Neostigmine reversal also enhanced the maximum degree of EMG amplitude recovery in both group C (83.6 [5.1] vs. 47.2 [6.1] %, P<0.01) and group R (85.6 [18.2]vs. 57.1 [6.3] %, P<0.05) compared to spontaneous recovery, respectively. The reversal effect of neostigmine did not differ significantly between cisatracurium and rocuronium. Conclusions: This porcine model demonstrated that neostigmine provides an adequate and timely IONM signal suppressed by both cisatracurium and rocuronium. These results can potentially expand the options for precision neuromuscular block management during IONM to improve vocal outcomes in thyroid surgery patients.