Normative electromyography data and influencing factors in intraoperative neuromonitoring using adhesive skin electrodes during thyroid surgery.

Background: Skin electrodes have been reported to be a useful alternative recording method for intraoperative neuromonitoring (IONM) and show typical electromyography (EMG) waveforms while overcoming the shortcomings of the EMG endotracheal tube. However, the skin electrodes showed relatively lower evoked amplitudes than other recording methods. In this study, we analyzed normative EMG data using skin electrodes and factors that affect the evoked amplitude of thyroid IONM. Methods: In total, 167 patients [242 nerves at risk (NAR)] who underwent thyroidectomy under IONM with adhesive skin electrodes were analyzed. A pair of skin electrodes was attached to the lateral border of the lamina of the thyroid cartilage. Evoked EMG data, including mean amplitude and latency, obtained after stimulation of the recurrent laryngeal nerve (RLN) and vagus nerve (VN), were collected and analyzed. Results: The mean amplitudes of RLN and VN recorded via skin electrodes were 255.48±96.53 and 236.15±69.72 µV, respectively. The mean latency of the right and left RLN was 3.22±0.03 and 3.49±0.08 mS, respectively. The mean latency of the right and left VN was 5.37±0.80 and 7.57±0.10 mS, respectively. The mean amplitude was significantly lower in the obesity, male, and total thyroidectomy (TT) groups. As body mass index (BMI) and age increased, the amplitude of EMG tended to decrease significantly. Conclusions: The evoked amplitude recorded with the skin electrodes was relatively low. A larger surgical extent, obesity, male sex, and age >55 years showed significantly lower evoked amplitudes.

Evaluation of Vertical Level Differences Between Left and Right Vocal Folds Using Artificial Intelligence System in Excised Canine Larynx.

OBJECTIVES: This study aimed to establish an artificial intelligence (AI) system to classify vertical level differences between vocal folds during vocalization and to evaluate the accuracy of the classification. METHODS: We designed models with different depths between the right and left vocal folds using an excised canine larynx. Video files for the data set were obtained using a high-speed camera system and a color complementary metal oxide semiconductor camera with global shutter. The data sets were divided into training, validation, and testing. We used 20,000 images for building the model and 8000 images for testing. To perform deep learning multiclass classification and to estimate the vertical level difference, we introduced DenseNet121-ConvLSTM. RESULTS: The model was trained several times using different numbers of epochs. We achieved the most optimal results at 100 epochs, and the batch size used during training was 16. The proposed DenseNet121-ConvLSTM model achieved classification accuracies of 99.5% and 88.0% for training and testing, respectively. After verification using an external data set, the overall accuracy, precision, recall, and f1-score were 90.8%, 91.6%, 90.9%, and 91.2%, respectively. CONCLUSIONS: The newly developed AI system may be an easy and accurate method for classifying superior and inferior vertical level differences between vocal folds. Thus, this AI system can be applied and may help in the assessment of vertical level differences in patients with unilateral vocal fold paralysis.

Discovering Potential Anti-Oral Squamous Cell Carcinoma Mechanisms from Kochiae Fructus Using Network-Based Pharmacology Analysis and Experimental Validation.

The natural product Kochiae Fructus (KF) is the ripe fruit of Kochia scoparia (L.) Schrad and is renowned for its anti-inflammatory, anticancer, anti-fungal, and anti-pruritic effects. This study examined the anticancer effect of components of KF to assess its potential as an adjuvant for cancer treatment. Network-based pharmacological and docking analyses of KF found associations with oral squamous cell carcinoma. The molecular docking of oleanolic acid (OA) with LC3 and SQSTM1 had high binding scores, and hydrogen binding with amino acids of the receptors suggests that OA is involved in autophagy, rather than the apoptosis pathway. For experimental validation, we exposed SCC-15 squamous carcinoma cells derived from a human tongue lesion to KF extract (KFE), OA, and cisplatin. The KFE caused SCC-15 cell death, and induced an accumulation of the autophagy marker proteins LC3 and p62/SQSTM1. The novelty of this study lies in the discovery that the change in autophagy protein levels can be related to the regulatory death of SCC-15 cells. These findings suggest that KF is a promising candidate for future studies to provide insight into the role of autophagy in cancer cells and advance our understanding of cancer prevention and treatment.

Effect of deferoxamine and ferrostatin-1 on salivary gland dysfunction in ovariectomized rats.

The mechanism underlying xerostomia after menopause has not yet been fully elucidated. This study aimed to investigate the mechanism of xerostomia and the effect of the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (FER) on salivary gland dysfunction in a postmenopausal animal model. Twenty-four female Sprague-Dawley rats were randomly divided into four groups: a SHAM group (n = 6, sham-operated rats), an OVX group (n = 6, ovariectomized rats), an FER group (n = 6, ovariectomized rats injected intraperitoneally with FER), and a DFO group (n = 6, ovariectomized rats injected intraperitoneally with DFO). GPX4 activity, iron accumulation, lipid peroxidation, inflammation, fibrosis, and salivary gland function were analyzed. Recovery of GPX4 activity and a decrease in iron accumulation and cytosolic MDA + HAE were observed in the DFO group. In addition, collagen I, collagen III, TGF-ß, IL-6, TNF-α, and TGF-ß levels were decreased in the DFO group compared to the OVX group. Recovery of GPX4 activity and the morphology of mitochondria, and reduction of cytosolic MDA + HAE were also observed in the FER group. In addition, decreased expression of inflammatory cytokines and fibrosis markers and increased expression of AQP5 were observed in both the DFO and FER groups. Postmenopausal salivary gland dysfunction is associated with ferroptosis, and DFO and FER may reverse the postmenopausal salivary gland dysfunction after menopause. DFO and FER are hence considered promising treatments for postmenopausal xerostomia.

Survey of Korean head and neck surgeons and endocrinologists for the surgical extent of 1.5 and 2.5 cm papillary thyroid carcinoma.

Background: The surgical extent of 1-4 cm papillary thyroid carcinoma (PTC) is controversial. We aimed to determine the current trend in the extent of thyroidectomy and prophylactic central neck dissection (pCND) for 1.5 and 2.5 cm PTC, which are the most clinically controversial sizes. Methods: The questionnaire was sent to 342 Korean Society of Head and Neck Surgery and 160 one branch of Korean Endocrine Society members from June to July 2021 by e-mail. A questionnaire included extent of thyroidectomy [hemithyroidectomy (Hemi) vs. total thyroidectomy (TT)] and pCND according to the tumor location and degree of extrathyroidal extension (ETE) at 1.5 or 2.5 cm PTC. We compared the proportion of respondents' preference for each scenario. Results: Fifty-seven of 342 surgeons and twenty-seven of 160 endocrinologists responded to the questionnaire. At 1.5 and 2.5 cm PTC without ETE, both groups preferred Hemi, and there was no difference between the groups. When 1.5 or 2.5 cm PTC with anterior minimal ETE was suspected, the preference for Hemi by endocrinologists was significantly lower than that by surgeons (P<0.05). When anterior and posterior gross ETE were suspected, TT was preferred in both groups. When anterior gross ETE was suspected, the preference for Hemi by endocrinologists was significantly lower than that by surgeons (P<0.05). There was no difference between the groups in the posterior gross ETE. Surgeons preferred Hemi and endocrinologists preferred TT for a 1.5 cm PTC located in the isthmus. The pCND showed a similar pattern in both groups according to the size and location of the tumor and the degree of ETE. The proportion of Hemi did not differ between high-experience and low-experience endocrinologists. Also, there was no significant difference in preference for surgical extent between low-volume and high-volume surgeons. Conclusions: TT was frequently preferred in tumors with a large size or gross ETE, and pCND was frequently preferred in cases of suspected gross ETE. This study shows as the extent of thyroid surgery may differ between endocrinologists and surgeons and this could be confusing to patient and affect the patient outcomes. Therefore, multidisciplinary approach considering the extent of surgery for thyroid cancer is recommended.

Diagnosis of Early Glottic Cancer Using Laryngeal Image and Voice Based on Ensemble Learning of Convolutional Neural Network Classifiers.

OBJECTIVES: The purpose of study is to improve the classification accuracy by comparing the results obtained by applying decision tree ensemble learning, which is one of the methods to increase the classification accuracy for a relatively small dataset, with the results obtained by the convolutional neural network (CNN) algorithm for the diagnosis of glottal cancer. METHODS: Pusan National University Hospital (PNUH) dataset were used to establish classifiers and Pusan National University Yangsan Hospital (PNUYH) dataset were used to verify the classifier's performance in the generated model. For the diagnosis of glottic cancer, deep learning-based CNN models were established and classified using laryngeal image and voice data. Classification accuracy was obtained by performing decision tree ensemble learning using probability through CNN classification algorithm. In this process, the classification and regression tree (CART) method was used. Then, we compared the classification accuracy of decision tree ensemble learning with CNN individual classifiers by fusing the laryngeal image with the voice decision tree classifier. RESULTS: We obtained classification accuracy of 81.03 % and 99.18 % in the established laryngeal image and voice classification models using PNUH training dataset, respectively. However, the classification accuracy of CNN classifiers decreased to 73.88 % in voice and 68.92 % in laryngeal image when using an external dataset of PNUYH. To solve this problem, decision tree ensemble learning of laryngeal image and voice was used, and the classification accuracy was improved by integrating data of laryngeal image and voice of the same person. The classification accuracy was 87.88 % and 89.06 % for the individualized laryngeal image and voice decision tree model respectively, and the fusion of the laryngeal image and voice decision tree results represented a classification accuracy of 95.31 %. CONCLUSION: The results of our study suggest that decision tree ensemble learning aimed at training multiple classifiers is useful to obtain an increased classification accuracy despite a small dataset. Although a large data amount is essential for AI analysis, when an integrated approach is taken by combining various input data high diagnostic classification accuracy can be expected.

Tensin Regulates Fundamental Biological Processes by Interacting with Integrins of Tonsil-Derived Mesenchymal Stem Cells.

Human tonsil-derived mesenchymal stem cells (TMSCs) have a superior proliferation rate and differentiation potential compared to adipose-tissue-derived MSCs (AMSCs) or bone-marrow-derived MSCs (BMSCs). TMSCs exhibit a significantly higher expression of the tensin3 gene (TNS3) than AMSCs or BMSCs. TNS is involved in cell adhesion and migration by binding to integrin beta-1 (ITG ß1) in focal adhesion. Here, we investigated the roles of four TNS isoforms, including TNS3 and their relationship with integrin in various biological processes of TMSCs. Suppressing TNS1 and TNS3 significantly decreased the cell count. The knockdown of TNS1 and TNS3 increased the gene and protein expression levels of p16, p19, and p21. TNS1 and TNS3 also have a significant effect on cell migration. Transfecting with siRNA TNS3 significantly reduced Oct4, Nanog, and Sox-2 levels. Conversely, when TNS4 was silenced, Oct4 and Sox-2 levels significantly increase. TNS1 and TNS3 promote osteogenic and adipogenic differentiation, whereas TNS4 inhibits adipogenic differentiation of TMSCs. TNS3 is involved in the control of focal adhesions by regulating integrin. Thus, TNS enables TMSCs to possess a higher proliferative capacity and differentiation potential than other MSCs. Notably, TNS3 plays a vital role in TMSC biology by regulating ITGß1 activity.

ACE2 and TMPRSS2 Immunolocalization and COVID-19-Related Thyroid Disorder.

Thyroid dysfunction has been reported to be an extrapulmonary symptom of COVID-19. It is important to identify the tissue subset that expresses angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2), which are essential for host infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in order to understand the viral pathogenesis of COVID-19-related thyroid dysfunction. We investigated the expression and distribution of ACE2- and TMPRSS2-expressing cells in the thyroid gland. RT-PCR and Western blotting were performed on human thyroid follicular cells (Nthy-ori3-1) and rat thyroid tissues to detect the expression levels of ACE and TMPRSS2 mRNA and proteins. We also analyzed the expression patterns of ACE2 and TMPRSS2 in 9 Sprague-Dawley rats and 15 human thyroid tissues, including 5 normal, 5 with Hashimoto's thyroiditis, and 5 with Graves' disease, by immunohistochemistry (IHC) and immunofluorescence. Both ACE2 and TMPRSS2 mRNAs and proteins were detected in the thyroid tissue. However, ACE2 and TMPRSS2 proteins were not expressed in thyroid follicular cells. In IHC, ACE2 and TMPRSS2 were not stained in the follicular cells. No cells co-expressed ACE2 and TMPRSS2. ACE2 was expressed in pericytes between follicles, and TMPRSS2 was mainly stained in the colloid inside the follicle. There was no difference in expression between the normal thyroid, Hashimoto's thyroiditis, and Graves' disease. SARS-CoV-2 does not directly invade the thyroid follicular cells. Whether SARS-CoV-2 infection of pericytes can affect COVID-19-related thyroid dysfunction warrants further study.

Tonsil mesenchymal stem cells-derived extracellular vesicles prevent submandibular gland dysfunction in ovariectomized rats.

Dry mouth that occurs after menopause significantly reduces the quality of life of the elderly. The extracellular vesicles derived from mesenchymal stem cells are being studied for application in various pathological conditions in the field of tissue regenerative medicine. This study is to investigate the therapeutic effect on salivary gland dysfunction occurring after ovariectomy using tonsil mesenchymal stem cells (T-MSCs)-derived extracellular vesicles. The rats were divided into the following groups: sham-operated rats (SHAM), rats that underwent ovariectomy (OVX), and rats that underwent OVX surgery and were simultaneously injected with T-MSC-derived extracellular vesicles (OVX+EV). The rats were sacrificed 6 weeks after ovariectomy. Estradiol levels decreased in the OVX group compared with those in the SHAM group. Extracellular vesicles had no effect on estradiol levels or estrogen receptor ß expression. The evaluation of pro-inflammatory cytokines, TNF-α and IL-6, increased in the OVX group and decreased in the OVX+EV group. The expressions of collagen I and TGFßI increased in the OVX group but decreased in the OVX+EV group. Moreover, to examine submandibular gland function, AQP5 and α-amylase expressions were downregulated in the OVX group, but improved upon exosome injection. In conclusion, T-MSC-derived extracellular vesicles are useful for the prevented submandibular gland dysfunction that occurs after menopause.

ACE2 and TMPRSS2 immunolocalization and oral manifestations of COVID-19.

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the host cells depends on the expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). We investigated the distribution of ACE2- and TMPRSS2-expressing cells in various oral tissues to identify the underlying mechanism of oral manifestations in patients with coronavirus disease 2019. SUBJECTS: We analyzed the expression patterns of ACE2 and TMPRSS2 in the oral mucosa (tongue, palate, and buccal mucosa), trigeminal ganglion, vessels, and salivary glands of 9 Sprague-Dawley rats using immunohistochemistry and immunofluorescence. RESULTS: ACE2 and TMPRSS2 were strongly expressed in the intermediate layer of the squamous epithelia of tongue papillae and buccal mucosa. ACE2- and TMPRSS2-positive cells were observed in the taste buds of the tongue. Additionally, ACE2 and TMPRSS2 were co-expressed in the ductal epithelium and acinar cells of salivary glands. Furthermore, both ACE2 and TMPRSS2 were stained in the neuronal cell body of trigeminal ganglia, but not in Schwann cells. Moreover, ACE2 and TMPRSS2 were expressed in capillaries, but not in venules/arterioles. CONCLUSIONS: SARS-CoV-2 can spread the suprabasal area of squamous epithelia of the oral mucosa, invades taste bud, trigeminal nerve, parotid gland, and microvessel, resulting in oral manifestations.

Clinical Significance of the Preoperative Thyroidectomy-Related Voice Questionnaire Score in Thyroid Surgery.

BACKGROUND: The thyroidectomy-related voice questionnaire (TVQ) is an efficient screening tool for detecting postoperative vocal dysfunction. The aim of this study was to confirm the significance of the preoperative TVQ score in thyroid surgery. METHODS: We examined 180 women who underwent total thyroidectomy with central lymph node dissection from March 2014 to May 2016. Based on the preoperative TVQ score, participants were categorized under "normal" (TVQ score <5) and "abnormal" (TVQ score ≥5) groups. The laryngoscopic examination and acoustic analysis were performed and the TVQ score assessed before and after surgery (2 weeks, 2 months, and 8 months). RESULTS: In the normal group, the TVQ score increased up to 2 months postoperatively and had decreased at 8 months postoperatively but was significantly higher than the preoperative TVQ score. In the abnormal group, the TVQ score increased up to 2 months postoperatively but had recovered similar to the preoperative TVQ score 8 months postoperatively. The preoperative TVQ score in the abnormal group moderately correlated with the final TVQ score; however, the preoperative TVQ score in the normal group did not correlate with the TVQ score 8 months postoperatively. CONCLUSION: During preoperative patient counseling, it is important to explain that voice changes without vocal cord palsy may occur postoperatively and that it may take a long time to resolve, particularly in patients with a normal preoperative TVQ score.

Investigation of attachment location of adhesive skin electrodes for intraoperative neuromonitoring in thyroid surgery: Preclinical and clinical studies.

BACKGROUND: Recently, adhesive skin electrodes have been reported to be useful for recording electromyographic signals from intrinsic laryngeal muscles for intraoperative neuromonitoring in thyroid surgery and have shown good results compared to existing recording methods. In this study, we investigated the optimal attachment location of adhesive skin electrodes for intraoperative neuromonitoring in both porcine models and human cases. METHODS: Attachment locations were divided vertically into upper, middle, and lower locations and horizontally into medial and lateral locations to determine the optimal location of placing adhesive skin electrodes preclinically in four porcine models. This study included a total of 78 patients who underwent thyroidectomy under intraoperative neuromonitoring with adhesive skin electrodes. Sixteen patients were monitored using both adhesive skin electrodes and an electromyographic endotracheal tube. Two pairs of skin electrodes were attached to the level of the thyroid cartilage lamina. Evoked electromyographic data, including data on mean amplitude and latency, obtained by stimulating the recurrent laryngeal nerve and vagus nerve, were collected. RESULTS: Lateral attachment of adhesive skin electrodes showed significantly higher evoked amplitudes than medial attachment in both animal models and human patients. In cases where skin electrodes and an electromyographic endotracheal tube were used together, the electromyographic endotracheal tube showed a significantly higher amplitude than skin electrodes, and laterally attached skin electrodes showed a significantly higher amplitude than medially attached skin electrodes. CONCLUSION: Intraoperative neuromonitoring using adhesive skin electrodes was feasible in both animal models and human patients. We suggest that it would be better to attach adhesive skin electrodes to the lateral side of the thyroid cartilage lamina. Lateral attachment closer to the cricoarytenoid joint may be better for measuring muscle movement around the cricoarytenoid joint.

Iatrogenic Cervical Epidermoid Cyst Following Tracheostomy.

Epidermoid cysts are generally benign lesions surrounded by squamous epithelium with cystic contents. The lining of the cysts produce keratin, which resemble a cheese-like material. They typically occur in the skin and mucous membranes and are congenital in origin; iatrogenic epidermoid cysts are rare. Epidermoid cysts are usually painless and asymptomatic, and their diagnosis is based on histological examination. This paper aims to present the case report of a 23-year-old patient with an iatrogenic epidermoid cyst that occurred following tracheostomy. The importance of preoperative radiological imaging in the diagnosis of epidermoid cysts is also highlighted.

Ultrasound Echogenicity of Papillary Thyroid Cancer Is Affected by Tumor Growth Patterns and Tumor Fibrosis.

BACKGROUND/AIM: The association between preoperative ultrasound (US) echogenicity and histopathological characteristics of papillary thyroid cancer (PTC) has been rarely investigated is not well characterized. This study evaluated a relationship between the clinical characteristics of PTC, histopathological phenomena including tumor growth patterns (TGPs) and tumor fibrosis (TF), and US echogenicity. PATIENTS AND METHODS: In total, 170 patients with PTC (<2 cm) underwent total thyroidectomy with central neck dissection. Demographics, US echogenicity, tumor size, extra-thyroidal extension (ETE), lymph node metastasis (LNM) within the central and lateral neck, TGPs, and TF percentage were reviewed. RESULTS: Patients with TGP II (encapsulated growth with partial pericapsular extension) and III (infiltrative growth) were more frequently burdened by ETE and lateral neck LNM compared to patients with TGP I (encapsulated growth with a well-defined cystic or solid characteristic). Older age was significantly deterministic of TGP III, and male gender and higher TF percentage were independent risk factors for lateral neck LNM. TGP III and TF were independent determining factors for marked hypoechogenicity on US. CONCLUSION: PTC with TGP II and III and higher tumor fibrosis exhibited more aggressive clinicopathologic behaviors. TGP III and TF were determinants for marked hypoechogenicity.

Clinical outcomes of T4a papillary thyroid cancer with recurrent laryngeal nerve involvement: a retrospective analysis.

Preoperative vocal cord palsy (VCP) may indicate locally invasive papillary thyroid cancer (PTC); using this relationship, we evaluated the clinical outcomes and risk factors for recurrence in post-thyroidectomy T4a PTC patients with recurrent laryngeal nerve (RLN) involvement. We retrospectively investigated thyroidectomy patients, recorded their clinical factors, recurrence rate, and pathological findings, and analysed the relationship between recurrence rate and clinical factors. Of 72 patients, 37 (51%) had preoperative VCP and 35 (49%) had normal preoperative vocal cord movement with confirmed intraoperative RLN invasion. Tracheal and esophageal invasion was observed in 13 (18%) and 15 (21%) patients, respectively. Thyroid cancer recurred in 18 (25%) patients over 58 months, resulting in 2 (3%) deaths. Recurrence was not associated with surgical extent, organ invasion, enlarged tumour size, or lymph node infiltration (p > 0.05). The recurrence rate was significantly higher in patients with positive resection margins (p < 0.05). T4a PTC patients with RLN involvement showed a poor prognosis. The recurrence rate was not affected by preoperative VCP, intraoperative detection of RLN invasion, nerve resection, nerve preservation by shaving, lymph node metastasis, or tracheal or esophageal invasion. The most important prognostic factor for recurrence was a positive resection margin.

Risk factors of suprasternal lymph node metastasis in papillary thyroid carcinoma with clinical lateral cervical lymph node metastasis.

BACKGROUND: Metastatic lymph nodes are occasionally found in suprasternal lymph nodes in patients with papillary thyroid cancer (PTC). However, limited studies have examined these lymph nodes thus far. Therefore, we investigated the frequency and risk factors of suprasternal lymph node metastasis in patients with PTC and lateral cervical lymph node metastasis. METHODS: A total of 85 patients with cN1b PTC underwent total thyroidectomy, central neck dissection, and ipsilateral selective neck dissection including suprasternal lymph node dissection. We analyzed the correlation between suprasternal lymph node metastasis and sex, age, tumor characteristics, and cervical lymph node metastasis status. RESULTS: Eleven (12.9%) patients had pathological suprasternal lymph node metastasis. Suprasternal lymph node metastasis was associated with tumors located in the inferior pole of the thyroid gland and level IV lymph node metastasis (P=0.005 and 0.014, respectively). Receiver operating characteristic curve analysis indicated that two or more level IV metastatic lymph nodes had the best predictive value for suprasternal lymph node metastasis (P<0.001). CONCLUSIONS: In patients with cN1b PTC, especially those with tumors in the inferior pole of the thyroid gland or level IV lymph node metastasis, greater attention should be paid to the suprasternal lymph nodes and suprasternal lymph node dissection should be routinely included as part of selective neck dissection.

The incidence of myocardial infarction and stroke in head and neck cancer patients.

Various treatment modalities are used for head and neck cancer (HNC). This study analyzed the incidence and risks of myocardial infarction (MI) and stroke by cancer site and treatment modality in 22,737 patients newly diagnosed with HNC registered in the Korean National Health Insurance Service database in 2007-2013. An additional 68,211 patients without HNC, stroke, or MI were identified as the control group. The risks for MI (hazard ratio [HR] = 1.38, 95% confidence interval [CI] 1.24-1.53), stroke (HR = 1.48, 95% CI 1.37-1.60), and mortality (HR = 5.30, 95% CI 5.14-5.47) were significantly higher in the HNC group. Analysis by cancer site showed the risk of MI and mortality was highest in hypopharynx cancer, while the risk of stroke was highest in nasopharynx and paranasal sinus cancer. Analysis by treatment modality showed the highest risks for MI (HR = 1.88, 95% CI 1.31-2.69) and mortality (HR = 2.95, 95% CI 2.75-3.17) in HNC patients receiving chemotherapy (CT) alone, while HNC patients receiving CT with surgery had the highest risk for stroke (HR = 1.81, 95% CI 1.14-2.88). Careful attention to MI and stroke risks in HNC patients is suggested, especially those who received both CT and radiotherapy.

Application of an Intraoperative Neuromonitoring System Using a Surface Pressure Sensor in Parotid Surgery: A Rabbit Model Study.

OBJECTIVES: Facial nerve monitoring (FNM) can be used to identify the facial nerve, to obtain information regarding its course, and to evaluate its status during parotidectomy. However, there has been disagreement regarding the efficacy of FNM in reducing the incidence of facial nerve palsy during parotid surgery. Therefore, instead of using electromyography (EMG) to identify the location and state of the facial nerve, we applied an intraoperative neuromonitoring (IONM) system using a surface pressure sensor to detect facial muscle twitching. The objective of this study was to investigate the feasibility of using the IONM system with a surface pressure sensor to detect facial muscle twitching during parotidectomy. METHODS: We evaluated the stimulus thresholds for the detection of muscle twitching in the orbicularis oris and orbicularis oculi, as well as the amplitude and latency of EMG and the surface pressure sensor in 13 facial nerves of seven rabbits, using the same stimulus intensity. RESULTS: The surface pressure sensor detected muscle twitching in the orbicularis oris and orbicularis oculi in response to a stimulation of 0.1 mA in all 13 facial nerves. The stimulus threshold did not differ between the surface pressure sensor and EMG. CONCLUSION: The application of IONM using a surface pressure sensor during parotidectomy is noninvasive, reliable, and feasible. Therefore, the IONM system with a surface pressure sensor to measure facial muscle twitching may be an alternative to EMG for verifying the status of the facial nerve.

Simple technique to preserve the external branch of the superior laryngeal nerve during thyroidectomy: Clinical practicability of an attachable nerve stimulator.

OBJECTIVE: This study aimed to demonstrate the usefulness of an attachable magnetic nerve stimulator for preservation of the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy. METHODS: We retrospectively analyzed 120 female patients, of which 60 underwent thyroidectomy with an attachable magnetic nerve stimulator (magnetic group) and the remaining 60 underwent thyroidectomy with a conventional method without EBSLN identification (control group). For both groups, objective and subjective voice parameters were investigated on the day before surgery and at 2 weeks and 2 months after surgery. RESULTS: In the magnetic group, a magnetic nerve stimulator was used to ligate only the site without cricothyroid muscle (CTM) twitching, and thyroid surgery was successfully performed without damage to the EBSLN. In the control group, objective voice parameters, including fundamental frequency, voice range profile (VRP), highest VRP (VRP-H), and maximal phonation time, and the subjective thyroidectomy-related voice questionnaire score were significantly decreased at 2 months after surgery compared to preoperative values. Compared to the control group, the magnetic group did not show a significant decrease in the objective VRP and VRP-H at 2 months after surgery. CONCLUSION: The use of metallic surgical instruments with an attachable magnetic nerve stimulator may provide surgeons with real-time feedback on CTM twitching feedback and EBSLN status. Compared to direct EBSLN identification during thyroidectomy, this is a simple, easy, and noninvasive method for EBSLN preservation that is useful, especially for less-experienced surgeons.