Intraoperative neuromonitoring during thyroidectomy does not decrease vocal cord palsy risk, but the cumulative experience of the surgeon may.

PURPOSE: To evaluate the influence of intraoperative neuromonitoring (IONM) on vocal cord palsy (VCP) rates and assess the temporal trends in VCP rates. METHODS: The subjects of this retrospective study were patients who underwent thyroidectomy for thyroid cancer between March, 2014 and June, 2022, at a university hospital in Korea. We compared VCP rates between the non-IONM and IONM groups and analyzed the risk factors for VCP and VCP rates over time. RESULTS: A total of 712 patients were included in the analysis. The rates of transient and permanent VCP did not differ significantly between the non-IONM and IONM groups. Transient VCP occurred in 4.6% and 4.3% patients (p = 0.878) and VCP was permanent in 0.7% and 0.4% patients (p = 0.607) in the non-IONM and IONM groups, respectively. Among the nerves at risk, transient damage occurred in 2.8% and 3.0% patients (p = 0.901), and permanent damage occurred in 0.4% and 0.3% (p = 0.688), respectively. Multivariate analysis revealed no significant risk factors for VCP. There was a significant decreasing trend in VCP rates over time as the cumulative number of cases increased (p = 0.017). CONCLUSIONS: IONM did not reduce the risk of VCP significantly. However, the declining trend of VCP rates suggests that the surgeon's experience may mitigate VCP risk.

Use of Indocyanine Green Fluorescence During Total Thyroidectomy to Identify Parathyroid Glands and Prevent Hypoparathyroidism.

INTRODUCTION: Total thyroidectomy is associated with a high rate of transient or permanent hypoparathyroidism. During surgery, indocyanine green (ICG) fluorescein angiography can be used to detect and preserve well-vascularized parathyroid glands. This technique has been introduced as an intraoperative support to prevent postoperative hypoparathyroidism. MATERIAL AND METHODS: One-hundred consecutive patients who had undergone total thyroidectomy were included in this study. Autofluoroscopy was used on the first dominant side of thyroidectomy and to identify the contralateral parathyroid glands. An intravenous bolus of 5 mg ICG (VERDYE, Diagnostic Green GmbH, Aschheim-Dornacht, Germany) was administered once. ICG fluorescein angiography was used as a "bridge" at the end of the first dominant hemithyroidectomy and after exposure of the parathyroid glands on the second side. This allowed us to (i) determine the vascularization of the first two parathyroid glands and (ii) define the blood vessels and thus the line of dissection of the parathyroid glands of the second resection side. Finally, autofluoroscopy was then applied outside the surgical area on the surgical specimen to assess forgotten parathyroid glands, which should therefore be re-implanted. Autofluoroscopy and ICG fluorescein angiography were evaluated in real time using the same technology, i.e., FLUOBEAM® LX (EUROPE - Fluoptics Grenoble, France; USA - Fluoptics Imaging Inc., Cambridge, MA, USA). The study was approved by the local ethics committee. RESULTS: Autofluorescence and ICG fluorescein angiography were performed without any problems in all cases. A total of 370 parathyroid glands were detected in this series. ICG changed the surgical strategy for the first-side parathyroid glands in 5% of cases, i.e,. they were not well-vascularized and were re-implanted. The rate of transient hypoparathyroidism was 19%. The percentage of parathyroids in the surgical specimen was 3.5% and all were re-implanted during the same surgery. There was no case of postoperative definitive hypoparathyroidism when at least one parathyroid gland with a high fluorescence intensity was preserved on the first side of resection. CONCLUSION: Use of ICG fluorescein angiography may contribute to predicting and thus preventing postoperative definitive hypoparathyroidism after total thyroidectomy. The results of this case series confirm recent studies. Caution is advised when weakly perfused parathyroid glands are discovered.

3D Transoral Endoscopic Thyroid.

Transoral endoscopic thyroidectomy with vestibular approach (TOETVA) is a feasible new surgical procedure that does not require visible incisions. We describe our experience with three-dimensional (3D) TOETVA. We recruited 98 patients who were willing to undergo 3D TOETVA. Inclusion criteria were: (a) patients with a neck ultrasound (US) with an estimated thyroid diameter of 10cm or less; (b) estimated US gland volume ≤45ml; (c) nodule size ≤50mm; (d) benign tumor, such as thyroid cyst, goiter with one nodule, or goiter with multiple nodules; (e) follicular neoplasia; and (f) papillary microcarcinoma without evidence of metastases. The procedure is performed using a three-port technique at the oral vestibule, a 10mm port for the 30° endoscope, and two additional 5mm ports for dissecting and coagulation instruments. The CO2 insufflation pressure is set at 6mmHg. An anterior cervical subplatysmal space is created from the oral vestibule to the sternal notch and laterally to the sternocleidomastoid muscle. Thyroidectomy is performed entirely 3D endoscopically with conventional endoscopic instruments and intraoperative neuromonitoring. There were 34% total thyroidectomies and 66% hemithyroidectomies. Ninety-eight 3D TOETVA procedures were successfully performed without any conversions. The mean operative time was 87.6 minutes (59-118 minutes) for lobectomy and 107.6 minutes (99-135 minutes) for bilateral surgery. We observed one case of transient postoperative hypocalcemia. Paralysis of the recurrent laryngeal nerve did not occur. The cosmetic outcome was excellent in all patients. This is the first case series of 3D TOETVA.

Exosomes Derived from Hypoxia-Cultured Human Adipose Stem Cells Alleviate Articular Chondrocyte Inflammaging and Post-Traumatic Osteoarthritis Progression.

Osteoarthritis (OA) is the most common age-related degenerative joint disease. Inflammaging, linking inflammation and aging, is found in senescent cells with the secretions of matrix-degrading proteins and proinflammatory cytokines. The senescence-associated secretory phenotype (SASP) plays a very important role in OA progression. However, there remains no effective way to suppress OA progression, especially by suppressing inflammaging and/or the chondrocyte SASP. Recent studies have shown that exosomes derived from hypoxia-cultured BMSCs can regenerate cartilage in OA animal models. Some reports have further indicated that exosomes secreted from MSCs contribute to the efficacy of MSC therapy in OA. However, whether hypoxia-cultured ADSC-secreted exosomes (hypoxia-ADSC-Exos) can alleviate the chondrocyte SASP or OA progression remains unclear. Accordingly, we hypothesized that hypoxia-ADSC-Exos have a beneficial effect on the normal functions of human articular chondrocytes (HACs), can attenuate the SASP of OA-like HACs in vitro, and further suppress OA progression in rats. Hypoxia-ADSC-Exos were derived from ADSCs cultured in 1% O2 and 10% de-Exo-FBS for 48 h. The molecular and cell biological effects of hypoxia-ADSC-Exos were tested on IL1-ß-induced HACs as OA-like HACs in vitro, and the efficacy of OA treatment was tested in ACLT-induced OA rats. The results showed that hypoxia-ADSC-Exos had the best effect on GAG formation in normal HACs rather than those cultured in normoxia or hypoxia plus 2% de-Exo-FBS. We further found that hypoxia-ADSC-Exos alleviated the harmful effect in OA-like HACs by decreasing markers of normal cartilage (GAG and type II collagen) and increasing markers of fibrous or degenerative cartilage (type I or X collagen), matrix degradation enzymes (MMP13 and ADAMT5), and inflammatory cytokines (TNFα and IL-6). More importantly, intra-articular treatment with hypoxia-ADSC-Exos suppressed OA progression, as evidenced by the weight-bearing function test and cartilage GAG quantification in ACLT rats. Moreover, through NGS and bioinformatic analysis, seven potential miRNAs were found in hypoxia-ADSC-Exos, which may contribute to regulating cellular oxidative stress and attenuating cell senescence. In summary, we demonstrated that hypoxia-ADSC-Exos, carrying potent miRNAs, not only improve normal HAC function but also alleviate HAC inflammaging and OA progression. The results suggest that hypoxia-ADSC-Exo treatment may offer another strategy for future OA therapy.

Multimodal Analgesia with Local Wound Infiltration and Intravenous Parecoxib for Thyroidectomy.

Background and objective: Adequate postoperative pain control is an important component to enhance recovery. Multimodal analgesia with various pain control techniques has been widely used to alleviate postoperative pain. The use of either wound infiltration or a superficial cervical plexus block has been reported to be effective for pain management after thyroid surgery. The present study evaluated the effect of multimodal analgesia using lidocaine wound infiltration combined with intravenous parecoxib for patients monitored after thyroidectomy. Materials and Methods: A total of 101 patients with a multimodal analgesia protocol being monitored after thyroidectomy were enrolled. After the induction of anesthesia, multimodal analgesia was performed through wound infiltration of 1% lidocaine and epinephrine at a ratio of 1:200,000 (5 µg/mL) combined 40 mg intravenous parecoxib before skin excision. Patients were divided into two groups for this retrospective analysis based on the injection dose of lidocaine they received. Patients in Group I (the control, n = 52) received a 5 mL injection solution, while those in Group II (the study, n = 49) received a 10 mL dosage in a time-sequential manner, in accordance with a previous clinical trial. The primary outcome was measuring postoperative pain intensity at rest, as well as during motion and coughing, which was measured at the postoperative anesthetic care unit (PACU) and on the first day after the operation (POD 1) in the ward. Pain intensity was assessed using a numerical rating scale (NRS). The secondary outcomes were postoperative adverse events including anesthetic-related side effects, as well as airway and pulmonary complications. Results: Most of the patients reported no pain or mild pain during the observation period. The patients in Group II had a lower pain intensity during motion than Group I (NRS 1.47 ± 0.89 vs. 1.85 ± 0.96, p = 0.043) when measured at the postoperative anesthetic care unit. Pain intensity during coughing was also significantly lower in the study group than in the control group (NRS 1.61 ± 0.95 vs. 1.96 ± 0.79, p = 0.049) when measured at the postoperative anesthetic care unit. There were no severe adverse events in either of the groups. Only one patient (1.9%) in Group I experienced temporary vocal palsy. Conclusions: The use of lidocaine with an equal volume of intravenous parecoxib provided comparable analgesia with minimal adverse events when monitoring thyroidectomy.

Conventional Total Thyroidectomy Using a Novel Single Retractor: Technical Note for Apollo®.

Despite the increasingly innovative techniques developed in thyroid surgery to offer patients minimally invasive and scarless interventions, conventional open procedures still account for most of the interventions performed in this field. The surgical incision length has been significantly reduced, from 6-9 cm to 3 cm, and therefore patients perceive the scar to be highly acceptable. In this technical note, we present the use of a new single retractor (APOLLO®; AFS MEDICAL GmbH, Teesdorf, Austria) for conventional open thyroidectomies with intraoperative neuromonitoring. This device offers several advantages: a) better exposure of the surgical field; b) less traction on skin flaps and neck muscles; and c) protection of the skin edges from the heat generated by energy-based devices/coagulating instruments, with consequent better healing.

Optimization of Intraoperative Neural Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery.

The application of intraoperative neural monitoring (IONM) has been widely accepted to improve surgical outcomes after thyroid surgery. The malfunction of an IONM system might interfere with surgical procedures. Thus, the development of anesthesia modalities aimed at ensuring functional neuromonitoring is essential. Two key issues should be taken into consideration for anesthetic management. Firstly, most patients undergo recurrent laryngeal nerve monitoring via surface electrodes embedded in an endotracheal tube. Thus, advanced video-assisted devices might optimize surface electrode positioning for improved neuromonitoring signaling accuracy. Secondly, neuromuscular blocking agents are routinely used during thyroid surgery. The ideal neuromuscular block should be deep enough for surgical relaxation at excision and recovered enough for an adequate signal f nerve stimulation. Proper neuromuscular block management could be achieved by titration doses of muscle relaxants and reversal agents.

Drawbacks of neural monitoring troubleshooting algorithms in transoral endoscopic thyroidectomy.

INTRODUCTION: The application of intraoperative neural monitoring (IONM) trouble-shooting algorithms procedures in transoral endoscopic thyroidectomy vestibular approach (TOETVA) was investigated. METHODS: Loss of signal (LOS) is defined as a loss of the primary electromyographic (EMG) normal biphasic waveform with reduced amplitude response to less than 100µV with a stimulation level intensity of 1-2mA. A systematic review of the IONM system at LOS was covered methodically: (i) correct endotracheal tube verification, (ii) stimulation of the recurrent laryngeal nerve (RLN) at entry point, (iii) ipsilateral or contralateral vagal nerve (VN) stimulation, and (iv) laryngeal twitch (LT). RESULTS: The function of 223 nerves at risk (NAR) was recorded with IONM. Twenty-seven (12%) NAR experienced a suspected LOS. LT could not be appreciated. In 15/27 (55%) cases, the application of the IONM trouble-shooting algorithm revealed upward displacement of the EMG tube (all orotracheal intubations). In 9 (4%) NAR, VN stimulation was not accomplished. In detail, there were n.5 left and n. 4 right VNs. Two VNs were ipsilateral, and 7 VNs contralateral. For EMG tube displacement, because the oral/nasal area is included in the aseptic field, it is less possible to re-check by the laryngoscope or fiberscope. CONCLUSIONS: A limit for applying the IONM trouble-shooting algorithm to TOETVA is determined by (a) inability to appreciate the LT, (b) difficulty in stimulating the ipsilateral and contralateral VN, and (c) remodeling EMG endotracheal tube position. A modified IONM trouble-shooting algorithm for TOETVA is proposed.

Use of Vivostat® Autologous Fibrin Sealant in Thyroid Surgery.

INTRODUCTION: Post-thyroidectomy hemorrhage is a rare but potentially life-threatening and unpredictable complication of thyroid surgery. Therefore, intraoperative bleeding control and hemostasis are crucial. However, the most efficient, cost-effective, and standardized way to achieve this is not clear. This study aimed to evaluate the outcome of total thyroidectomy (TT) and partial thyroidectomy (PT) performed using the Vivostat® hemostatic system (Vivostat A/S, Lillerød, Denmark). METHODS: Patients underwent TT and PT for benign and malignant diseases (multinodular goiter, Graves' disease, differentiated thyroid carcinoma). The primary endpoint was 1st-day postoperative drain output and bleeding that required reintervention. Secondary endpoints included surgery duration and postsurgical complications (vocal fold palsy, hypocalcemia, seroma, wound infection). RESULTS: Between October 2020 and December 2020, 56 patients were enrolled; 69.6% female; mean age 49.5 years. The mean 24-h drain output was 40 ml. No redo surgery was needed. Seroma was present in 5.3% of cases; no permanent vocal palsy or hypocalcemia was observed. CONCLUSION: This study shows that the Vivostat® system is both safe and effective for hemostasis during thyroid surgery.

C2 Xplore® for Intermittent and Continuous Laryngeal Nerve Monitoring: Technical Note.

Due to the direct anatomical relationship between the recurrent laryngeal nerve (RLN) and the thyroid gland, the function and anatomical integrity of the RLN is fundamentally at risk in every thyroid operation. While a RLN morbidity rate of less than 5% is achieved in specialized clinics, the morbidity rates are significantly higher in non-specialized centers. Thus, the aim is to reduce the complication rate by establishing standardized interventions. Exact knowledge of the anatomical course of the RLN, the nerve-sparing dissection technique and the supportive use of intraoperative neuro-monitoring (IONM) to identify anatomical variations are the basis for nerve-sparing surgery. We tested the new C2 Xplore® system (inomed Medizintechnik GmbH, Emmendingen, Germany) as a tool for performing intermittent and continuous laryngeal nerve monitoring during thyroid surgery. The C2 Xplore® helps to enhance surgeon-IONM interaction, and provides comprehensive digital EMG documentation with EMG quantification. EMG artifacts are removed. Image quality and EMG feedback are highly acceptable for intraoperative monitoring. The C2 Xplore® system does not have a deleterious impact on the proper function of other surgical instruments. C2 Xplore® is effective for intraoperative monitoring, optimizing RLN dissection, and supporting surgical deliberations, and for forensic use and research. A step-by-step C2 Xplore® procedure is described.

Status of Alternative Approaches for Thyroidectomy: Is There Any Evidence to Substitute in Place of Conventional Surgery?

Over the past 20 years, various alternative cervical minimally invasive (partly endoscopically assisted) and extracervical endoscopic (partly robot-assisted) approaches have been developed. All of these alternative access methods aim at optimizing the cosmetic results. In principle, the indication for the use of alternative access procedures does not differ from that for conventional surgery. Nonetheless, appropriate experience in traditional thyroid surgery and suitable patient selection, taking into account thyroid volumes and the underlying pathology, are important prerequisites. General contraindications for an alternative approach are large goiter with symptoms of compression, advanced thyroid carcinoma, recurrent interventions or previous radiotherapy in the operating area. The alternative surgical approaches to the thyroid can be divided into cervical minimally invasive, extracervical endoscopic (robot-assisted) and transoral procedures. This article gives an overview of the clinically used alternative approaches in thyroid surgery. The desire for an optimal cosmetic result should not be prioritized over patient safety. Only a few alternative procedures (minimally invasive video-assisted thyroidectomy, transaxillary robot-assisted thyroidectomy) can currently be viewed as a useful addition to conventional thyroid surgery, even when in responsible, experienced hands for a selected group of patients.

An Improved Recurrent Laryngeal Nerve-Monitoring Device: Technical Note for Nim Vital™.

A new device for monitoring the laryngeal nerves during thyroid surgery has been developed. NIM Vital™ (Medtronic Xomed, Inc., Jacksonville, FL, USA) incorporates (a) a new wireless design, (b) NIM NerveTrendTM (Medtronic Xomed) EMG reporting, (c) intelligent noise-reduction technology that suppresses artifacts, (d) smart troubleshooting pop-up alerts, and (e) NIM Nervassure ™ (Medtronic Xomed) for continuous monitoring. This device offers enhanced stability and flexibility for both intermittent and continuous laryngeal nerve monitoring. The new NIM NerveTrend ™ EMG reporting makes it possible to track the recurrent laryngeal nerve condition throughout a procedure, even when using intermittent nerve monitoring. During both continuous and intermittent monitoring, green, yellow and red status bars provide visual information and associated tones provide audible cues, making it easy to monitor nerve function and interpret EMG trends. This new tool for laryngeal nerve monitoring has the potential to augment nerve dissection during surgery. Measurements of long-term outcome are needed to establish their efficacy.

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.

New Paradigms for Neural Monitoring in Thyroid Surgery.

Intraoperative neuromonitoring (IONM) in thyroid gland surgery provides real-time feedback to the endocrine surgeon regarding the electrophysiological consequences of surgical manipulation of the laryngeal nerves. The goal of monitoring modalities is to detect surgical or physiological insults to the recurrent laryngeal nerve (RLN) while they are still reversible or, in cases where prevention is not an option, to minimize the damage done to these structures during thyroidectomy. In recent decades, monitoring of the RLN has become a fundamental part of endocrine surgery. IONM is a feasible procedure in both open and endoscopic, robotic thyroidectomy. Experts in IONM have organized a working group of general, endocrine, head and neck ENT surgeons and endocrinologists (International Neural Monitoring Study Group; INMSG) to develop standards for practicing this technique in endoscopic and robotic thyroidectomy. This paper presents recent clinical and research experience with intraoperative neural monitoring for thyroid gland surgery.

Endoscopic screening for synchronous esophageal neoplasia among patients with incident head and neck cancer: Prevalence, risk factors, and outcomes.

Esophageal squamous-cell neoplasia (ESCN) is a common second primary neoplasia found in patients with head-and-neck squamous-cell carcinoma (HNSCC). This study sought to identify the risk factors for synchronous ESCN and how they influence survival in HNSCC patient. Eight hundred and fifteen incident HNSCC patients were prospectively recruited for endoscopy screening for ESCN using white-light imaging, narrow-band imaging, Lugol chromoendoscopy, and pathological confirmation. Associated lifestyle and clinicopathological data were collected. The interquartile follow-up period cutoffs were 11.3, 20.5 and 34.9 months. 124 patients (15.2%) were diagnosed as having synchronous ESCN (66 low-grade dysplasia, 29 high-grade dysplasia, and 29 esophageal squamous-cell carcinoma). Consumption of alcohol, but not betel nut or cigarette, was significantly associated with the presence of synchronous ESCN (adjusted odds ratio [aOR] = 7.1 and 10.9 for former and current drinkers, respectively). There was an interaction between cumulative dose of alcohol consumption and alcohol flushing response on the development of ESCN. High-dose drinkers with flush response were 16.9 times more likely to have esophageal high-grade dysplasia/SCC than non-drinkers. Compared with oral cavity cancer patients, those with hypopharyngeal, laryngeal and oropharyngeal cancer were 6.8, 4.6 and 2.8 times more likely to have esophageal high-grade dysplasia/SCC. HNSCC patients with synchronous ESCN had lower overall survival than those without (p < 0.0001). In conclusion, surveillance of ESCN is strongly recommended for the high-risk subpopulation of HNSCC patients, especially drinkers who have a flush response to alcohol, and those with distant metastasis of index cancer and cancers in hypopharynx, oropharynx and larynx.

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.