Facial nerve monitoring during parotid gland surgery: a systematic review and meta-analysis

Update on the Treatment of Salivary Gland Carcinomas

Salivary gland carcinoma is a rare form of head and neck carcinoma, but it comprises a variety of subsites and histologic subtypes that each present with unique clinical courses and management challenges. Preoperative work-up generally consists of fine-needle aspiration cytology and MRI. However, because of the large variety of subtypes, there are often challenges obtaining a histologic diagnosis before surgery. Upfront surgery at the primary site leads to the greatest improvement in survival. Posttreatment surveillance of these patients is important. This article discusses some of the current controversies in the management of salivary gland carcinomas.

An analysis of health-related quality of life in children and adolescents after parotidectomy based on patient-reported outcomes

PURPOSE

To assess health-related quality of life (HRQoL) and its influencing factors in these pediatric patients undergoing parotidectomy.

METHODS

This was a cross-sectional study that included 37 children and adolescents (≤ 19 years) with parotid gland tumors who were treated in Sichuan Cancer Hospital between January 2006 and November 2021. HRQoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30). The Wilcoxon rank sum test was used to analyze the factors influencing patients' HRQoL.

RESULTS

37 children and adolescents were included in the study, including 22 cases of benign tumors and 15 cases of malignant tumors. All patients underwent surgery, and some patients with malignant tumors received radiotherapy or chemotherapy. Malignancy, permanent facial palsy, and Frey syndrome were associated with worse HRQoL in children and adolescents with parotid gland tumors. Radiotherapy and no cervical lymph node dissection were associated with worse HRQoL in pediatric patients with malignancy. The surgical approach of parotid is not a factor influencing HRQoL.

CONCLUSION

Factors associated with HRQoL in children and adolescents with parotid gland tumors include pathological types, permanent facial palsy, and Frey syndrome. In addition, factors affecting patients with malignancy include lateral lymph node dissection and radiotherapy.

Comprehensive Mapping and Dynamic Monitoring of the Temporal Branch of the Facial Nerve in Complex Cranial Reconstruction Surgery and Revision Cranioplasty

Facial nerve (FN) injury is a significant risk during complex cranial reconstruction surgeries, especially in revision cases where normal anatomy is distorted. The authors introduce a technique to mitigate FN injury, including preoperative FN mapping, intraoperative FN mapping, and continuous FN monitoring. Preoperative mapping uses a handheld ball-tip stimulator to elicit compound muscle action potentials (CMAP) in the frontalis muscle. Needle electrodes are placed above the orbital margin to record responses, starting at the stylomastoid foramen and extending until the entire temporal branch is mapped. Intraoperatively, continuous mapping is achieved using an electrified insulated suction device, allowing dynamic mapping during soft tissue dissection. Continuous monitoring involves placing stimulation electrodes near the stylomastoid foramen and recording CMAP responses from the frontalis and orbicularis oculi/orbicularis oris muscles. The authors tested this technique in 5 patients. The authors successfully mapped the temporal branch of the FN with isolated frontalis CMAP recordings in all patients. Intraoperative FN mapping and continuous monitoring were successfully performed in all cases. Two patients experienced complete cessation of FN CMAPs, which resumed upon loosening the tension on the myocutaneous flap held by fishhooks. One patient showed a 39% decrement in frontalis CMAP that did not recover. Despite these issues, all patients had intact FN function postoperatively and at follow-up. Our technique shows promise in mitigating FN injury during complex cranial reconstruction and cranioplasty revision surgery. Further research with a larger cohort is needed to confirm efficacy and statistical significance.

Intraparotid Sentinel Lymph Node Dissection for Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Surgical management of head and neck cutaneous melanoma (HNCM) has evolved tremendously since sentinel lymph node biopsy (SLNB) has become the prominent tool of prognosis and staging. This meta-analysis aimed to evaluate the safety and efficiency of intraparotid SLNB compared with a more extensive surgery of superficial parotidectomy (SP).

METHODS

The electronic database of PubMed and Scopus were searched for publications until 10 March 2022. In addition, the study included data of patients from our institution who underwent cherry-picking procedures. Pooled estimates were calculated using the random-effects model. Heterogeneity was calculated using the I2 test.

RESULTS

The pooled result regarding the rate of SLNB excision success was 97 % (95 % confidence interval [CI], 0.95-0.99; p < 0.0001), and the pooled probability of a positive SLNB result was 16 % (95 % CI 0.12-0.20; p < 0.0001). Failure of SLNB had pooled results of 4 % (95 % CI 0.02-0.06; p < 0.0009). For SP, no study examining N0 HNCM patients has met the authors' inclusion criteria. Cherry-picking SLNB had temporary and permanent facial nerve paralysis relative risks (RRs) of 0.12 (95 % CI 0.06-0.27; p < 0.0001) and 0.46 (95 % CI 0.17-1.22; p < 0.0001), respectively, compared with historical data from four weighted meta-analyses of SP.

CONCLUSIONS

The data from this study suggest that intraparotid SLNB performed for N0 HNCM patients is a safe and reliable procedure, with very low complication rates. Failure of the procedure did not exceed 4 %. Therefore, intraparotid SLNB may be superior to an extensive surgery such as SP and should be examined in future prospective trials.

Impact of Surgeon's Experience and Tumor's Nature in the Use of Intraoperative Facial Nerve Monitoring in Superficial Parotidectomy. Preliminary Results from a Single-Center Retrospective Analysis

To assess the effectiveness of intraoperative facial nerve monitoring (IFNM) compared to non-monitoring in the prevention of post-operative facial nerve palsy during superficial parotidectomy. Patients treated with curative intent for parotid gland tumors between January 2020 and January 2022 were included. The study population has been divided in 2 groups, based on IFNM: the group A included patients operated with IFNM, whilst group B was the non-monitoring group. A further classification focused on the pathologies and the surgeons' experience. The study group included 58 patients, 27 female and 31 male. The mean age was 45.7 yr (range 36-78). No statistical difference has been found in post-operative HB grade between group A and B. The analysis of patients affected by pleomorphic surface lobe adenomas of the parotid did not show a statistical difference in HB outcome (p > 0.05). The analysis of the effect of surgeons' experience in IFNM advantage did not show statistical difference for superficial parotid tumors. The results of the present study suggest that the use of IFNM during parotid surgery is not mandatory to preserve the VII nerve function, both in case of primary tumor and in case of recurrence, and even when surgery is performed by less experienced surgeon compared to those cases treated by a more experienced surgeon.

Identification of critical mitochondrial hub gene for facial nerve regeneration

Mitochondria play a critical role in nerve regeneration, yet the impact of gene expression changes related to mitochondria in facial nerve regeneration remains unknown. To address this knowledge gap, we analyzed the expression profile of the facial motor nucleus (FMN) using data obtained from the Gene Expression Omnibus (GEO) database (GSE162977). By comparing different time points in the data, we identified differentially expressed genes (DEGs). Additionally, we collected mitochondria-related genes from the Gene Ontology (GO) database and intersected them with the DEGs, resulting in the identification of mitochondria-related DEGs (MIT-DEGs). To gain further insights, we performed functional enrichment and pathway analysis of the MIT-DEGs. To explore the interactions among these MIT-DEGs, we constructed a protein-protein interaction (PPI) network using the STRING database and identified hub genes using the Degree algorithm of Cytoscape software. To validate the relevance of these genes to nerve regeneration, we established a rat facial nerve injury (FNI) model and conducted a series of experiments. Through these experiments, we confirmed three MIT-DEGs (Myc, Lyn, and Cdk1) associated with facial nerve regeneration. Our findings provide valuable insights into the transcriptional changes of mitochondria-related genes in the FMN following FNI, which can contribute to the development of new treatment strategies for FNI.

Continuous intraoperative neuromonitoring of the facial nerve predicts postoperative facial palsy in parotid surgery: a prospective study

PURPOSE

Facial palsy (FP) is the most significant complication of parotidectomy. Currently, the use of intermittent intraoperative neuromonitoring (iIONM) in parotid surgery facilitates nerve detection, which is paramount to nerve protection. Continuous IONM (cIONM), as applied in thyroid surgery, enables real-time information on electrophysiological nerve status through continuous nerve stimulation, thereby allowing consequent amplitude analysis. To date, the application of cIONM in parotid surgery has not been noted in literature.

METHODS

We performed parotidectomies with anterograde facial nerve visualization using cIONM in 32 consecutive patients in a prospective study (German Register of clinical studies-DRKS 00011051) during the period October 2016 to January 2020. After the facial trunk had been exposed, an atraumatic stimulation electrode was placed and the nerve was stimulated at 3 Hz, at a low threshold (0.62 ± 0.06 mA), for the entire duration of the preparation. Selected electrophysiological parameters were collected and compared to postoperative facial nerve function, measured by the House-Brackmann grading system.

RESULTS

In the post hoc analysis, a significant correlation between a drop in amplitude (< 50% of the "baseline" amplitude) and postoperative FP was recorded (p = 0.001). True positive prediction of FP was noted in 14 out of 16 patients and true negative in 10 out of 16. The sensitivity was 87.5% (AUC 0.75), with a high negative predictive value of 83.3%.

CONCLUSION

cIONM has significant value in predicting postoperative FP in parotidectomy. Future development of an acoustic/optic warning system in IONM devices could prevent nerve injury in real time.

The risk of facial nerve palsy after benign parotidectomy. A quality project

BACKGROUND

Facial nerve palsy is a potential complication of parotidectomy for benign salivary gland tumours, necessitating a comprehensive understanding of its incidence and associated risk factors for improved patient counselling and preoperative planning.

AIM/OBJECTIVES

This single-centre retrospective study aimed to assess the rate of facial nerve palsy following benign parotidectomy at a University Teaching Hospital.

MATERIAL AND METHODS

Over a 3-year period, 160 patients undergoing parotid surgery for benign tumours were included. Data, encompassing sex, age, operation technique, tumour pathology, facial nerve function, and follow-up duration, were collected from medical records. Exclusion criteria comprised patients with prior parotid gland surgery or preoperative facial nerve palsy.

RESULTS

The study revealed a 3.75% incidence of facial nerve palsy with no total paralysis post-parotidectomy for benign disease. Pleomorphic adenoma (50.6%) and Warthin's tumour (44.4%) were the predominant tumour types. No significant differences were noted between groups with and without postoperative facial palsy based on obtained covariates.

CONCLUSION AND SIGNIFICANCE

Our findings endorse partial superficial parotidectomy and extracapsular dissection as low-risk treatments for benign parotid tumours. However, prospective studies are warranted to elucidate recovery rates and long-term consequences of facial nerve palsy, contributing to refined surgical approaches and patient care in parotid surgery.

The Utility of Intraoperative Neuromonitoring in Pediatric Surgical Oncology

BACKGROUND

Intraoperative nerve monitoring (IONM) is a technique used to decrease the possibility of nerve-associated morbidity and damage to nearby neural structures during complex surgical procedures. The use and potential benefits of IONM in pediatric surgical oncology are not well-described.

METHODS

An overview of the current literature was performed to elucidate the various techniques that may be useful to pediatric surgeons for resection of solid tumors in children.

RESULTS

The physiology and common types of IONM relevant to the pediatric surgeon are described. Important anesthetic considerations are reviewed. Specific applications for IONM that may be useful in pediatric surgical oncology are then summarized, including its use for monitoring the recurrent laryngeal nerve, the facial nerve, the brachial plexus, spinal nerves, and lower extremity nerves. Troubleshooting techniques regarding common pitfalls are then proposed.

CONCLUSION

IONM is a technique that may be beneficial in pediatric surgical oncology to minimize nerve injury during extensive tumor resections. This review aimed to elucidate the various techniques available. IONM should be considered as an adjunct for the safe resection of solid tumors in children in the proper setting with the appropriate level of expertise. A multidisciplinary approach is advised. Additional studies are necessary to further clarify the optimal use and outcomes in this patient population.

LEVELS OF EVIDENCE

Level III.

Amide proton transfer-weighted magnetic resonance imaging for the differentiation of parotid gland tumors

Purpose

To assess the usefulness of amide proton transfer-weighted (APTw) imaging in the differentiation of parotid gland tumors.

Materials and methods

Patients with parotid gland tumors who underwent APTw imaging were retrospectively enrolled and divided into groups according to pathology. Two radiologists evaluated the APTw image quality independently, and APTw images with quality score ≥3 were enrolled. The maximum and average values of APTw imaging for tumor lesions (APTmax and APTmean) were measured. The differences in APTmax and APTmean were compared between malignant tumors (MTs) and benign tumors (BTs), as well as between MTs and pleomorphic adenomas (PAs) and between MTs and Warthin tumors (WTs). Independent-samples t-test, Kruskal-Wallis H test, and receiver operating characteristic (ROC) curve analyses were used for statistical analysis.

Results

Seventy-three patients were included for image quality evaluation. In this study, 32/73 and 29/73 parotid tumors were scored as 4 and 3, respectively. After excluding lesions with quality score ≤2 (12/73), the APTmean and APTmax of MTs were 4.15% ± 1.33% and 7.43% ± 1.61%, higher than those of BTs 2.74% ± 1.04% and 5.25% ± 1.54%, respectively (p < 0.05). The areas under the ROC curve (AUCs) of the APTmean and APTmax for differentiation between MTs and BTs were 0.819 and 0.821, respectively. MTs indicated significantly higher APTmean and APTmax values than those of PAs (p < 0.05) and WTs (p < 0.05). The AUCs of the APTmean and APTmax for differentiation between MTs and PAs were 0.830 and 0.815 and between MTs and WTs were 0.847 and 0.920, respectively.

Conclusion

Most APTw images for parotid tumors had acceptable image quality for APTw value evaluation. Both APTmax and APTmean can be used to differentiate MTs from BTs and to differentiate MTs from subtype parotid gland tumors.

[Results of a nationwide survey on the treatment of salivary gland diseases in German hospitals]

BACKGROUND

Salivary gland diseases are an important part of the work of ENT physicians in hospitals. The treatment strategies depend, among other things, on the doctrine at the respective location.

OBJECTIVE

The aim of this questionnaire-based study was to assess the current diagnostic workup and therapeutic strategies for salivary gland diseases in German otorhinolaryngology departments.

MATERIALS AND METHODS

A survey was performed using a 25-question online questionnaire sent to all German otorhinolaryngology department directors.

RESULTS

The questionnaire was answered by 92 of 175 otorhinolaryngology departments (52.6%). In the diagnosis of salivary gland tumors, a dominance of sonography and MRI was shown. Fine- and core-needle aspiration were not performed by more than 50% of the clinics. The dominant technique for parotidectomy was under microscopic control (82%). In 99% of clinics, EMG was used during resection of the parotid gland for intraoperative monitoring of the facial nerve. There was a trend towards performing partial parotidectomies (85%), lateral parotidectomies (70%), and extracapsular dissections (57%) for benign tumors of the parotid gland. The treatment concepts for malignant tumors were inconsistent.

CONCLUSION

In particular, the treatment strategy and extent of surgery for benign and malignant salivary gland tumors differed depending on location. The choice of palliative (drug) therapy was also diverse. Prospective multicenter studies could help to develop evidence-based treatment strategies.

Facial nerve dysfunction following parotidectomy: role of intraoperative facial nerve monitoring

PURPOSE

Facial nerve dysfunction (FND) is a frequent and serious parotidectomy outcome. Intraoperative facial nerve monitoring (IFNM) is an increasingly used technique to identify the facial nerve (FN) and minimize its injury. This study aimed to evaluate the determinant factors in the presence and severity of FND after parotidectomy, including IFNM.

STUDY DESIGN, SETTING AND METHODS

A total of 48 patients consecutively submitted to parotidectomy between 2005 and 2020 in a tertiary hospital were retrospectively analyzed. The House-Brackmann Scale (HBS) was used to assess the severity of FND.

RESULTS

There was a mean age of 54.2 ± 17.8 years, 50% were male. Pleomorphic adenoma (41.7%) and Warthin's tumor (25.0%) were most common. From the 23 patients (47.9%) who developed some degree of FND (HBS score of 3.41 ± 1.53), 19 (82.6%) showed facial movement recovery, with a mean recovery time of 4.78 ± 2.53 months. IFNM was performed in 39.6% of the surgeries. The use of IFNM (p = 0.514), the type of surgery-partial or total parotidectomy-(p = 0.853) and the type of histology-benign or malignant lesion-(p = 0.852) did not significantly influence the presence of FND in the postoperative period. However, in the subgroup of patients who developed FND, the HBS value was significantly lower in cases of benign pathology (p = 0.002) and in patients who underwent IFNM (p = 0.017), denoting a significantly lower severity.

CONCLUSION

In the present study, IFNM and the existence of a benign lesion have been shown to be associated with lower severity of FND.

[Posttherapeutic quality of life after treatment of salivary gland cancer]

BACKGROUND

In addition to overall survival and recurrence-free interval, posttherapeutic quality of life has been established as an independent criterion for treatment evaluation. Thereby, both the specific changes in the head and neck region and their objectification represent a particular challenge for the assessment of quality of life. There are different validated questionnaires available.

OBJECTIVE

Based on the literature, an overview of the relevant questionnaire instruments is given and the specific aspects in patients with salivary gland cancer are presented.

MATERIALS AND METHODS

A selective literature search was conducted to collect publications dealing with the assessment of health-related quality of life in head and neck tumor patients. The papers were critically appraised and summarized.

RESULTS

There are some validated questionnaires available to measure quality of life in patients with head and neck tumors as well as a few specific questionnaires for patients after parotidectomy.

CONCLUSION

By assessing quality of life using standardized questionnaire instruments, disease and treatment consequences can be objectified. Thus, the need for supportive measures, e.g., for rehabilitation in facial nerve palsy, can be identified more reliably.

Partial Parotidectomy under Local Anaesthesia without Regional Block Assisted by Electromyographic Facial Nerve Monitoring - A Case Report

The Rationale

This study describes a partial parotidectomy (PP) under local anaesthesia (LA) without regional block (LAwRB) assisted by electromyographic monitoring of the facial nerve, to consolidate the feasibility, efficacy and safety of these procedures without general anaesthesia (GA).

Patient Concerns

An 82-year-old with a lump in the left parotid gland suspected for non-Hodgkin lymphoma (NHL) needed a histological examination to start chemotherapy.

Diagnosis and Treatments

Because of multiple comorbidities, the authors performed a PP under LAwRB electromyographically guided by the NIM Vital (Medtronic)™.

Outcomes

The procedure was quick and did not require conversion to GA. The histopathological examination confirmed the NHL. No haematoma, sialocoele, earlobe numbness and transient or permanent facial palsy were observed.

Take-Away Lessons

The electrophysiologic monitoring of the facial nerve improves the efficacy, safety and feasibility of parotid surgery under LA, avoiding adverse effects of GA, need of regional block and reducing hospital stay.

Tratamiento quirúrgico de la patología tumoral de la glándula parótida. Estudio descriptivo de 263 parotidectomías

Introducción y objetivo: Los tumores salivales representan el 3-10% de los tumores de cabeza y cuello, siendo el 75-80% de origen parotídeo y en su mayoría benignos. La parotidectomía es una técnica quirúrgica que consiste en la exéresis de la glándula parótida. Existen diversos tipos; parotidectomía superficial (PS), parotidectomía superficial parcial (PSP) y parotidectomía total (PT). En esta última, al no respetarse el nervio facial (NF), las complicaciones son más frecuentes. Nuestro objetivo es analizar el resultado (tasa de recidiva y complicaciones) de la parotidectomía como técnica quirúrgica empleada en el manejo de la patología parotídea, así como evaluar qué prueba complementaria es la más eficaz en el diagnostico prequirúrgico de la patología parotídea tumoral. Material y método: Se realiza un estudio retrospectivo incluyendo 263 pacientes tratados mediante PS o PT entre enero de 2004 y diciembre de 2020 en el Hospital Universitario de Fuenlabrada. Se registraron datos demográficos, tiempo de evolución de la lesión, pruebas complementarias, protocolo quirúrgico y complicaciones postoperatorias. Se analiza principalmente la correlación positiva entre las pruebas realizadas prequirúrgicas (PAAF, ecografía, TC y RMN), con el diagnóstico definitivo anatomopatológico obtenido tras examinar la pieza quirúrgica. También se describe la tasa de paresia y parálisis facial y otras complicaciones habidas. Resultados: Se incluyeron 263 pacientes tratados mediante parotidectomía. El tiempo de evolución medio de las lesiones parotídeas fue de 15 meses (DE 19.88). La sensibilidad de la PAAF en nuestro estudio fue de 68.7%. Se realizó ecografía en un 44.10% de los pacientes, TC en un 77.94% y RMN en un 15.20%, mostrando una sensibilidad de 18.05%, 31.21% y 45%, respectivamente. La cirugía más frecuente fue la PS (43.3%, 114/263), seguida por la PSP (41.1%, 108/263) y, por último, la menos habitual fue la PT (15.58%, 41/263). Los tumores benignos fueron más frecuentes (84.79%, 223/263), siendo el adenoma pleomorfo el más frecuente, 45.73% (102/223). Dentro del grupo de tumores malignos (15.20%, 40/263), el más habitual fue el carcinoma mucoepidermoide (17.5%, 7/40) y las metástasis (17.5%, 7/40). La paresia facial, según la escala de House-Brackmann, fue leve (grado I y II) y transitoria en la mayoría de los casos, apareciendo en un 31.55%. Tras un periodo medio de seguimiento de 6 años no se han encontrado recidivas post parotidectomía por ningún tipo tumoral en nuestro estudio. Conclusión: En nuestra muestra, los tumores benignos representaron la gran mayoría de la patología parotídea. Dentro de este grupo, el adenoma pleomorfo fue el más frecuente. La PAAF fue la prueba complementaria con mejor correlación con el diagnostico anatomopatológico definitivo, seguida por la RMN. La paresia facial leve (grados I y II) y transitoria fue la complicación postquirúrgica mas habitual.

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.

Apparent Diffusion Coefficient (ADC) Histogram Analysis in Parotid Gland Tumors: Evaluating a Novel Approach for Differentiation between Benign and Malignant Parotid Lesions Based on Full Histogram Distributions

The aim of this study was to assess the diagnostic value of ADC distribution curves for differentiation between benign and malignant parotid gland tumors and to compare with mean ADC values. 73 patients with parotid gland tumors underwent head-and-neck MRI on a 1.5 Tesla scanner prior to surgery and histograms of ADC values were extracted. Histopathological results served as a reference standard for further analysis. ADC histograms were evaluated by comparing their similarity to a reference distribution using Chi2-test-statistics. The assumed reference distribution for benign and malignant parotid gland lesions was calculated after pooling the entire ADC data. In addition, mean ADC values were determined. For both methods, we calculated and compared the sensitivity and specificity between benign and malignant parotid gland tumors and three subgroups (pleomorphic adenoma, Warthin tumor, and malignant lesions), respectively. Moreover, we performed cross-validation (CV) techniques to estimate the predictive performance between ADC distributions and mean values. Histopathological results revealed 30 pleomorphic adenomas, 22 Warthin tumors, and 21 malignant tumors. ADC histogram distribution yielded a better specificity for detection of benign parotid gland lesions (ADChistogram: 75.0% vs. ADCmean: 71.2%), but mean ADC values provided a higher sensitivity (ADCmean: 71.4% vs. ADChistogram: 61.9%). The discrepancies are most pronounced in the differentiation between malignant and Warthin tumors (sensitivity ADCmean: 76.2% vs. ADChistogram: 61.9%; specificity ADChistogram: 81.8% vs. ADCmean: 68.2%). Using CV techniques, ADC distribution revealed consistently better accuracy to differentiate benign from malignant lesions (“leave-one-out CV” accuracy ADChistogram: 71.2% vs. ADCmean: 67.1%). ADC histogram analysis using full distribution curves is a promising new approach for differentiation between primary benign and malignant parotid gland tumors, especially with respect to the advantage in predictive performance based on CV techniques.

Patient safety and quality improvements in parotid surgery

Parotidectomy is the mainstay treatment for tumors of the parotid gland. In an effort to improve clinical outcomes, several modern surgical techniques and perioperative interventions have been evaluated and refined. This review discusses current and actively debated perioperative interventions aimed at improving patient safety and the quality of parotidectomy. Relevant high-impact literature pertaining to preoperative diagnostic modalities, intraoperative surgical techniques, and postoperative care will be described.

Management of Malignant Salivary Gland Conditions

Salivary cancers are rare tumors that arise in major and minor salivary glands. Workup almost always includes fine-needle aspiration or core needle biopsy in select cases. Imaging with ultrasound, computed tomography, or MRI is also helpful, particularly with MRI to assess facial nerve involvement or skull base involvement. Preserving function of the facial nerve is of paramount importance, and the standard of care is to not sacrifice facial nerve except in instances of gross encasement and inability to dissect tumor off of the nerve. Adjuvant radiation and chemotherapy offer survival advantages for select patients.

Systematic review and meta-analysis of modified facelift incision versus modified Blair incision in parotidectomy

Surgical removal is the treatment of choice for many neoplasms of the parotid gland. This meta-analysis aimed to evaluate the differences between parotidectomy using a modified facelift incision (MFI) and parotidectomy using a modified Blair incision (MBI). A systematic search of the available literature in PubMed, Embase and the Cochrane Library was performed. Studies of adult patients who underwent open parotidectomy with presumed benign parotid neoplasms based on preoperative examinations were reviewed. The surgical outcomes of the MFI and MBI groups were collected. Intraoperative and postoperative parameters, including operative time, tumor size, cosmetic satisfaction, and incidences of facial palsy, Frey's syndrome and salivary complications, were compared. Dichotomous data and continuous data were analyzed by calculating the risk difference (RD) and the mean difference (MD) with the 95% confidence interval (CI), respectively. Seven studies were included in the final analysis. The pooled analysis demonstrated that the cosmetic satisfaction score was significantly higher in the MFI group (MD = 1.66; 95% CI 0.87-2.46). The operative duration in the MFI group was significantly longer than that in the MBI group (MD = 0.07; 95% CI 0.00-0.14). The MFI group exhibited a smaller tumor size (MD = - 2.27; 95% CI - 4.25 to - 0.30) and a lower incidence of Frey's syndrome (RD = - 0.18; 95% CI - 0.27 to - 0.10). The incidence of postoperative temporary facial palsy (RD = - 0.05; 95% CI - 0.12 to 0.03), permanent facial palsy (RD = - 0.01; 95% CI - 0.06 to 0.03) and salivary complications (RD = - 0.00; 95% CI - 0.05 to 0.05) was comparable between the two groups. Based on these results, MFI may be a feasible technique for improving the cosmetic results of patients who need parotidectomy when oncological safety can be ensured.

Correlation between Electrophysiological Change and Facial Function in Parotid Surgery Patients

This observational study investigated intraoperative electrophysiological changes and their correlation with postoperative facial expressions in parotidectomy patients with visual confirmation of facial nerve (FN) continuity. Maximal electromyography(EMG) amplitudes of the facial muscles corresponding to temporal, zygomatic, buccal and mandibular branches were compared before/after FN dissection, and facial function at four facial regions were evaluated before/after parotidectomy in 112 patients. Comparisons of 448 pairs of EMG signals revealed at least one signal decrease after FN dissection in 75 (67%) patients. Regional facial weakness was only found in 13 of 16 signals with >50% amplitude decreases. All facial dysfunctions completely recovered within 6 months. EMG amplitude decreases often occur after FN dissection. An amplitude decrease >50% in an FN branch is associated with a high incidence of dysfunction in the corresponding facial region. This study tries to establish a standard facial nerve monitoring (FNM) procedure and a proper facial function grading system for parotid surgery that will be useful for the future study of FNM in parotid surgery.

An update on extracapsular dissection for the management of parotid gland pleomorphic adenoma

Superficial parotidectomy has been the gold standard for surgical removal of benign mobile parotid gland tumours. The comparatively newer technique of extracapsular dissection, which involves careful dissection of the tumour itself without the need for formal gland excision, has gained popularity in recent years. Tumours can be removed via smaller incision, and the technique reduces the risk of Frey's syndrome (gustatory sweating) and hollowing at the site of surgery. The risk of facial nerve damage can also be lower with extracapsular dissection. If done carefully, the incidence of tumour recurrence, particularly for pleomorphic adenomas, is comparable with formal parotidectomy. We provide a brief update overview of the current evidence for extracapsular dissection in the treatment of benign parotid tumours and include several meta-analyses which provide evidence for the safety of the technique. We have also included our audited results of over 100 recent extracapsular dissections, with 0% incidence of permanent facial nerve weakness, reported Frey's syndrome and recurrence rates over the last 5 years.

Facial Nerve Monitoring under Different Levels of Neuromuscular Blockade with Cisatracurium Besilate in Parotid Tumour Surgery

Background

Anaesthesia can alter neuronal excitability and vascular reactivity and ultimately lead to neurovascular coupling. Precise control of the skeletal muscle relaxant doses is the key in reducing anaesthetic damage.

Methods

A total of 102 patients with the normal functioning preoperative facial nerve who required parotid tumour resection were included in this study. Facial nerve monitoring was conducted intraoperatively. The surgeon stimulated the facial nerve at different myorelaxation intervals at TOF% (T4/T1) and T1% (T1/T0) and recorded the responses and the amplitude of electromyogram (EMG). Body movements (BM) or patient-ventilator asynchrony (PVA) was recorded intraoperatively.

Results

In parotid tumour resection, T1% should be maintained at a range of 30 to 60% while TOF% should be maintained at a range of 20 to 30%. Analysis of the decision tree model for facial nerve monitoring suggests a partial muscle relaxation level of 30% < T1% ≤ 50% and TOF ≤ 60%. A nomogram prediction model, while incorporating factors such as sex, age, BMI, TOF%, and T1%, was constructed to predict the risk of BM/PVA during surgery, showing good predictive performance.

Conclusions

This study revealed an adequate level of neuromuscular blockade in intraoperative parotid tumour resection while conducting facial nerve monitoring. A visual nomogram prediction model was constructed to guide anaesthetists in improving the anaesthetic plan.

Single-surgeon parotidectomy outcomes in an academic center experience during a 15-year period

OBJECTIVE

As large single-surgeon series in the literature are lacking, we sought to review a single-surgeon's experience with parotidectomy in an academic center, with a focused analysis of pathology, technique, and facial nerve (FN) weakness. Benchmark values for complications and operative times with routine trainee involvement and without continuous FN monitoring are offered.

MATERIALS AND METHODS

All patients who underwent parotidectomy, performed by D. G. D., for benign and malignant disease between January 2004 and December 2018 at an academic center were reviewed.

RESULTS

A total of 924 parotidectomies, with adequate evaluatable data were identified. The majority of patients had benign tumors (70.9%). Partial/superficial parotidectomy was the most common approach (65.7%). Selective FN branch sacrifice was rare (12.3%), but significantly more common among patients with malignant pathology (33.8% vs 3.5% for benign, P < .0001). Among patients with intact FN, post-operative short- and long-term FN weaknesses were rare (6.5% and 1.7%, respectively). These rates were lower among patients with benign tumors (5.4% and 1.3%). Partial/superficial parotidectomy for benign tumors was associated with a low rate of short- and long-term FN weaknesses (2.7% and 0.9%). Mean OR time was 185 minutes.

CONCLUSION

This is the largest single-surgeon series on parotidectomy, spanning 15 years. We demonstrate excellent long- and short-term FN paresis rates with acceptable operative times without regular use of continuous FN monitoring and with routine trainee involvement. These findings may provide valuable insight into parotid tumor pathology, FN outcomes, and feasibility and expectations of performing parotidectomy in an academic setting.

LEVEL OF EVIDENCE

4.