Development of a Machine Learning Algorithm to Forecast the Likelihood of Postoperative Neurological Complications in Patients With Parotid Tumors

Objective: The objective of this study was to create and verify a machine learning-driven predictive model to forecast the likelihood of facial nerve impairment in patients with parotid tumors following surgery. Methods: We retrospectively collected data from patients with parotid tumors between 2013 and 2023 to develop a prediction model for postoperative facial nerve dysfunction using 5 ML techniques: Logistic Regression (Logit), Random Forest (RF), XGBoost (XGB), Artificial Neural Network (ANN), and Support Vector Machine (SVM). Predictor variables were screened using binomial-LASSO regression. Results: The study had a total of 403 participants, out of which 56 individuals encountered facial nerve damage after the surgery. By employing binomial-LASSO regression, we have successfully identified 8 crucial predictive variables: tumor kind, tumor pain, surgeon's experience, tumor volume, basophil percentage, red blood cell count, partial thromboplastin time, and prothrombin time. The models utilizing ANN and Logit achieved higher area under the curve (AUC) values, namely 0.829, which was significantly better than the SVM model that had an AUC of 0.724. There were no noticeable disparities in the AUC values between the ANN and Logit models, as well as between these models and other techniques like RF and XGB. Conclusion: Using machine learning, our prediction model accurately predicts the likelihood that patients with parotid tumors may experience facial nerve damage following surgery. By using this model, doctors can assess patients' risks more accurately before to surgery, and it may also help optimize postoperative treatment techniques. It is anticipated that this tool would enhance patients' quality of life and therapeutic outcomes.

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.

Intraoperative Facial Nerve Involvement in Parotid Tumours - A Retrospective Analysis in a Tertiary Care Centre

Purpose

The study aims to provide a comprehensive overview of the various malignant and benign parotid tumours and evaluate the predictive factors for intraoperative nerve involvement leading to facial palsy (FP).

Methods

It is a single-centre retrospective analysis for reviewing the involvement of facial nerve in post- parotidectomy patients. The clinical database from January 2012 to December 2020 was included in the study with a follow-up period of a minimum of 2 years. To maintain homogeneity, all squamous cell carcinomas of level 2 nodes involving parotid or residual/recurrent disease of the oral cavity requiring parotid dissection were excluded.

Results

A total of 248 patients (171 benign; 77 malignant) were evaluated with a mean age of 46.48 ± 10.76 years. The presence of malignancy increases the risk of FP (p = 0.027). 37 (14.92%) patients with FP were detected which included 34 with partial [32.35% in malignant; 62.16% in recurrent pleomorphic adenoma (RPA)] and 3 with total paralysis (66.67% in malignant; 33.33% in RPA). The recurrence of pleomorphic adenoma increases FP. While old age, larger size, hard fixed swelling with masseteric space (MS) infiltration appeared as risk factors for FP in malignant tumours (p = 0.047; p = 0.004; p < 0.00001 respectively).

Conclusion

Tumour size, malignancy, hard fixed mass, masseteric space infiltration, recurrence, and age > 45yrs have been statistically significant predictive factors for intraoperative facial nerve involvement leading to FP. The study also revealed that FP occurred more commonly when there was concurrent involvement of both superficial and deep lobes but was not statistically significant.

Surgical management of Warthin tumor: long-term follow-up of 224 patients from 2002 to 2018

PURPOSE

Warthin tumors (WT) are the second most common benign parotid gland neoplasms. They can occur as synchronous or metachronous lesions in 6-10% of cases. This study aims to compare the complication rate in 224 patients who underwent extracapsular dissection (ECD) or superficial parotidectomy (SP) for the treatment of a WT.

METHODS

This retrospective study was conducted at the Department of Maxillo-Facial Surgery at the University of Naples "Federico II" from February 2002 to December 2018 on a group of patients who underwent surgical treatment for WT. The type of surgical technique was chosen based on Quer's classification. The complications evaluated were facial nerve palsy, hematoma, Frey's syndrome, and bleeding.

RESULTS

A total of 224 patients treated from 2002 to 2018 for Warthin tumor were included in the study. Two hundred elven had solitary tumors (94.1%) and 13 had multicentric lesions (5.8%), of which 9 cases presented synchronous lesions and 4 cases presented metachronous lesions. Extracapsular dissection (ECD) was performed in 130 patients (58.3% of cases) and superficial parotidectomy (SP) in the other 94 (41.7% of cases).

CONCLUSIONS

We consider both surgical techniques as valid. In our opinion, it is essential to study each case based on Quer's Classification to obtain the best surgical outcome. Based on a lower observed rate of complications such as facial nerve palsy, Frey's syndrome, and bleeding, ECD seems to be the best option for the surgical treatment of Quer Class I lesions.

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.

Facial nerve monitoring in parotid gland surgery: Design and feasibility assessment of a potential standardized technique

Background

Even though the use of nerve monitoring during parotid gland surgery is not the gold standard to prevent damage to the nerve, it surely offers some advantages over the traditional approach. Different from thyroid surgery, where a series of steps in intraoperative nerve monitoring have been described to confirm not only the integrity but-most importantly-the function of the recurrent laryngeal nerve, in parotid gland surgery, a formal guideline to follow while dissecting the facial nerve has yet to be described.

Methods

A five-year retrospective study was done reviewing the intraoperative records of patients who underwent parotid gland surgery under neural monitoring. The operative findings regarding the neuromonitoring process, particularly in regard to the amplitude of two main branches, were revised. A literature search was done to search for guidelines to follow when a facial nerve loss of signal is encountered.

Results

Fifty-five patients were operated on using the Nim 3 Nerve Monitoring System (Medtronic); 31 were female patients, and 47 patients had benign lesions. Minimum changes were observed in the amplitude records after a comparison was made between the first and the last stimulation. There were only three articles discussing the term loss of signal during parotid gland surgery.

Conclusion

Today, no sufficient attention has been given to the facial nerve monitoring process during parotidectomy. This study proposes a formal guideline to follow during this procedure as well as an instruction to consider when a loss of signal is observed to develop a uniform technique of facial nerve stimulation.

Imaging of Facial Nerve With 3D-DESS-WE-MRI Before Parotidectomy: Impact on Surgical Outcomes

OBJECTIVE

The intra-parotid facial nerve (FN) can be visualized using three-dimensional double-echo steady-state water-excitation sequence magnetic resonance imaging (3D-DESS-WE-MRI). However, the clinical impact of FN imaging using 3D-DESS-WE-MRI before parotidectomy has not yet been explored. We compared the clinical outcomes of parotidectomy in patients with and without preoperative 3D-DESS-WE-MRI.

MATERIALS AND METHODS

This prospective, non-randomized, single-institution study included 296 adult patients who underwent parotidectomy for parotid tumors, excluding superficial and mobile tumors. Preoperative evaluation with 3D-DESS-WE-MRI was performed in 122 patients, and not performed in 174 patients. FN visibility and tumor location relative to FN on 3D-DESS-WE-MRI were evaluated in 120 patients. Rates of FN palsy (FNP) and operation times were compared between patients with and without 3D-DESS-WE-MRI; propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to adjust for surgical and tumor factors.

RESULTS

The main trunk, temporofacial branch, and cervicofacial branch of the intra-parotid FN were identified using 3D-DESS-WE-MRI in approximately 97.5% (117/120), 44.2% (53/120), and 25.0% (30/120) of cases, respectively. The tumor location relative to FN, as assessed on magnetic resonance imaging, concurred with surgical findings in 90.8% (109/120) of cases. Rates of temporary and permanent FNP did not vary between patients with and without 3D-DESS-WE-MRI according to PSM (odds ratio, 2.29 [95% confidence interval {CI} 0.64-8.25] and 2.02 [95% CI: 0.32-12.90], respectively) and IPTW (odds ratio, 1.76 [95% CI: 0.19-16.75] and 1.94 [95% CI: 0.20-18.49], respectively). Conversely, operation time for surgical identification of FN was significantly shorter with 3D-DESS-WE-MRI (median, 25 vs. 35 min for PSM and 25 vs. 30 min for IPTW, P < 0.001).

CONCLUSION

Preoperative FN imaging with 3D-DESS-WE-MRI facilitated anatomical identification of FN and its relationship to the tumor during parotidectomy. This modality reduced operation time for FN identification, but did not significantly affect postoperative FNP rates.

Predicting postoperative facial nerve paralysis by using intraoperative nerve monitoring during parotid surgery

OBJECTIVES

To investigate a method for predicting postoperative facial nerve paralysis (POFNP) during parotid surgery using intraoperative nerve monitoring (IONM).

METHODS

We assessed prediction for POFNP by using IONM, comparing between stimulation in the facial nerve trunk and each branch by using facial nerve monitoring. The amplitude response ratio (ARR) was calculated for the trunk/periphery. In addition, we then examined the correlation between ARR and time to recovery of paralyzed branches.

RESULTS

372 branches of 93 patients did not develop POFNP and were classified as group A. Among 20 patients who developed POFNP, 51 branches without POFNP were classified as group B, and 29 branches with POFNP were classified as group C. The ARR was approximately 1 in group A and B. but less than 0.5 in all branches in Group C. When the cut off value of ARR was set at 0.55, the sensitivity, specificity, and accuracy of POFNP diagnosis by ARR were 96.5%, 93.1%, and 96.8%, respectively.

CONCLUSION

Using IONM during parotid surgery enables easy prediction of POFNP.

Feasibility of facial nerve monitoring using adhesive surface electrodes during parotidectomy: a comparative study with needle electrodes

PURPOSE

Electrophysiological monitoring of the facial nerve during parotidectomy has been reported as an adjunctive method to prevent facial nerve injury. Classically, a needle electrode is used to obtain electromyographic (EMG) signals from facial muscles during facial nerve monitoring (FNM) of parotid surgery, likewise adhesive surface electrodes. This study aimed to investigate the feasibility of performing FNM with surface electrodes during parotid surgery and to compare EMG values with needle electrodes.

METHODS

Thirty patients who underwent parotidectomy under FNM using adhesive surface and needle electrodes were included. Two pairs of adhesive surface electrodes and needle electrodes were used for FNM during parotid surgery. Mean amplitudes were collected after electrical facial nerve stimulation at 1 mA after specimen removal.

RESULTS

The mean amplitude of the adhesive surface electrodes was 226.50 ± 118.44 μV (orbicularis oculi muscle) and 469.6 ± 306.06 μV (orbicularis oris muscle), respectively. The mean amplitude of the needle electrodes was 449.85 ± 248.10 μV (orbicularis oculi muscle) and 654.66 ± 395.71 μV (orbicularis oris muscle), respectively. The mean amplitude of the orbicularis oris muscle was significantly greater than that of the orbicularis oculi. The amplitude values measured in the orbicularis oculi muscle showed significant differences between the needle and skin electrodes.

CONCLUSIONS

Facial nerve monitoring (FNM) using adhesive surface electrodes is feasible in parotid surgery. Although the mean amplitude value of the surface electrode was relatively lower than that of the needle electrode, the surface electrode is considered a feasible and safe EMG recording device for FNM in parotid surgery.

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.

Posterior auricular artery as a novel anatomic landmark for identification of the facial nerve: A clinical study

BACKGROUND

In our previous cadaveric study, we highlighted the posterior auricular artery (PAA) as a potential landmark for early identification of facial nerve (FN) when performing parotidectomy. However, further clinical study is critically needed before this landmark could be applied in clinical practice.

METHODS

For 31 patients enrolled, we tried to identify the FN by the guide of the PAA during parotidectomy. Additionally, the FN function was evaluated during follow-up.

RESULTS

PAA could be exposed in 28 out of 31 (90.3%) patients during parotidectomy. Moreover, the FN trunk could be identified by the guide of the PAA in all these 28 patients with identifiable PAA. Furthermore, no iatrogenic FN damage happened in this study and the transient FN dysfunction rate was 5.7%.

CONCLUSION

The PAA is an ideal landmark for early identification of the FN trunk when performing parotidectomy.

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.

Simple Technique Using an Additional Landmark to Reliably Identify the Trunk of Facial Nerve During Parotidectomy: a Cadaveric and Clinical Correlation Study

The incidence of facial palsy in parotid surgeries is up to 50% transient and 17% complete facial palsy. Locating facial nerve trunk during parotid surgery can be tricky despite using the standard landmarks. During a cadaveric dissection, we came across a simple technique to identify the trunk of facial nerve which we have also tried to use it in clinical setting and found it to be useful. Parotidectomy was done in 12 cadaveric hemi-faces. The distance between the mastoid tip and the tympanic segment of facial nerve was measured. The distance of the facial nerve and mastoid tip and tympanomastoid suture and facial nerve was measured. The trunk of facial nerve was found to cross the tympanomastoid sulcus-mastoid tip at around 8-10 mm from the mastoid tip in 70% of the cases. We extrapolated this information in 5 cases of parotidectomy in operative setting. We were able to identify facial nerve trunk accurately in 4/5 cases. Imaginary line connecting the mastoid tip and tympanomastoid suture can be used to locate the probable position of the facial nerve trunk reliably during parotidectomy.

Outcome of Postoperative Facial Nerve Function Following Electromyographic Facial Nerve Monitoring During Parotidectomy for Benign Lesions: a Retrospective Study

Does use of Facial nerve monitors during parotidectomy decrease incidence of facial paralysis/paresis without use of facial paresis? This study was done to compare the incidence, grade and risk factors of facial palsy in patients undergoing parotidectomy for benign parotid lesions with and without use of facial nerve monitor. This is a retrospective study. Eighty parotid patients operated for benign parotid lesions from 2013 to 2020 were retrospectively analysed. Demography details, history of the patients, history of addictions, clinical examination findings, investigation findings like the biopsy report, FNAC report, imaging i.e., CT / MRI / USG, use of intraoperative facial nerve monitor, time taken to identify the facial nerve, postoperative facial nerve palsy, facial nerve stimulation test and recovery time were analysed. Fifty patients were operated without use of facial nerve monitor, and 30 patients were operated using facial nerve monitor. Postoperative facial nerve complications were seen in 28 out of 80 patients (35%). Postoperative facial nerve complications were observed in 5 out of 30 patients (20%) in whom facial nerve monitoring was used. Marginal mandibular nerve palsy was observed in 4 patients and 1 patient had weakness of both marginal mandibular and orbital branches. While in postoperative facial nerve complications were observed in 25 out of 50 patients (50%), marginal mandibular nerve palsy was observed in 15 patients (40%), grade 3 facial palsy was observed in 3 out of 50 patients (6%), and grade 4 facial palsy were observed in 2 out of 50 patients (4%). The use of intraoperative FNM significantly lowered the incidence of paralysis.

Comparison of various surgical incisions in parotidectomy: A systematic review and network meta-analysis

Background

This network meta-analysis aimed to comprehensively compare the operative and postoperative outcomes of different parotidectomy incisions.

Methods

Embase, PubMed, Web of Science, and Cochrane Central Register of Controlled Trials were searched up to April 2022. A complete Bayesian network meta-analysis was performed using the Markov Monte Carlo method in OpenBUGS.

Results

Seventeen studies with 1609 patients were included. Thirteen were retrospective cohort studies, three were prospective cohort studies, and one was a randomized controlled study. The quality of evidence was rated as very low in most comparisons. The incision satisfaction score of the modified facelift incision (MFI), retroauricular hairline incision (RAHI), V-shaped incision (VI) were higher than that of the modified Blair incision (MBI) (MBI vs. MFI: mean difference [MD] -1.39; 95% credible interval [CrI] -2.23, -0.57) (MBI vs. RAHI: MD -2.25; 95% CrI -3.40, -1.12) (MBI vs. VI: MD -2.58; 95% CrI -3.71, -1.46); the tumor size treated by VI was smaller than that by MBI (MD 5.15; 95% CrI 0.76, 9.38) and MFI (MD 5.16; 95% CrI 0.34, 9.86); and the risk of transient facial palsy in the MFI was lower than that in the MBI (OR 2.13; 95% CrI 1.28, 3.64). There were no differences in operation time, drainage volume, wound infection, hematoma, salivary complications, Frey syndrome, or permanent facial palsy between incision types.

Conclusion

The traditional MBI is frequently used for large tumor volumes, but the incision satisfaction score is low and postoperative complication control is poor. However, emerging incisions performed well in terms of incision satisfaction scores and control of complications. More randomized controlled trials are needed to compare the different parotidectomy incisions. Patients should be fully informed about the characteristics of each incision to make the most informed decision, along with the physician’s advice.

Systematic Review Registration

PROSPERO, identifier CRD42022331756

A retrospective study of parotid gland tumors at a single institution

The aim of the present study was to analyze the clinical characteristics, surgical treatments and clinical outcome of patients with parotid gland tumors and to compare the results with those cited in the literature. A retrospective study was conducted in 140 patients (male, n=77; female, n=63) with parotid gland tumors who underwent parotidectomy at Hokuto Hospital Department of Otolaryngology-Head and Neck Surgery (Obihiro, Japan) between April 2007 and December 2021. Of the 140 patients enrolled, 118 (84.3%) patients had benign tumors, including 63 (45%) patients with pleomorphic adenomas and 43 (30.7%) patients with Warthin tumors, and 22 patients (15.7%) had parotid carcinoma. Comparison of the three groups of patients with parotid gland tumors indicated that pack years as an indicator of smoking status were significantly higher in patients with Warthin tumors than in those with parotid carcinomas (P=0.011) or pleomorphic adenoma (P<0.001). Fine-needle aspiration cytology (FNAC) was non-diagnostic for only 6 (4.3%) of 140 patients. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNAC by both conventional smear and liquid-based cytology (LBC) for parotid carcinomas were 70, 99, 93.3, 94.4 and 82.9%, respectively. Among the 22 patients with parotid carcinoma, extended total/total and superficial parotidectomy were performed in 10 (45%) and 11 (50%) cases, respectively. Total and selective neck dissection of the area from level II to I, II and III were performed in 6 (24%) and 7 (32%) patients, respectively. Postoperative radiotherapy (50 Gy) was performed in 15 (68%) patients. The overall survival (OS) and disease-free survival (DFS) rates at 5 years were 51.5 and 76.4%, respectively. Univariate analysis revealed that age >65 years was significantly associated with poorer 5-year OS (P<0.001) and DFS (P<0.001). Multivariate analysis revealed that an age of more than 65 years combined with high-grade histologic malignancy was associated with worse DFS (P=0.02; hazard ratio, 3.628; 95% confidence interval, 1.283-9.514). In conclusion, the clinical characteristics and treatment outcomes of parotid gland tumors were consistent with the results of previous reports. Smoking may be closely related to the pathogenesis of Warthin tumors. LBC potentially provides improved accuracy in FNAC.

Pattern of facial nerve palsy during parotidectomy: a single-center experience

OBJECTIVE

This study was performed to report and analyze the prevalence of permanent facial nerve paralysis following parotidectomy for various benign and malignant lesions in a single center.

METHODS

This single-center retrospective study included all patients who underwent parotidectomy (total and superficial) for benign and malignant tumors and chronic inflammatory diseases during a 6-year period. Patients who had previously undergone an operation of the parotid gland and those with preoperative facial weakness were excluded.

RESULTS

The study included 127 patients ranging in age from 14 to 83 years (median, 45.89 years). Most patients were female (n = 83, 65.4%). The most prevalent procedure was superficial parotidectomy (n = 117, 92.1%), followed by total parotidectomy (n = 6, 4.7%). The average operative duration was 138 minutes (range, 80-400 minutes). Histopathology revealed that 109 (85.8%) patients had benign tumors, 14 (11.0%) had malignant tumors, and 4 (3.1%) had chronic sialadenitis. Only two patients sustained an injury to the cervical branch of the facial nerve.

CONCLUSION

In this single-center experience of parotid surgery, the rates of transient and permanent facial paralysis were acceptably low at 9.0% and 1.6%, respectively, for all pathologies.

Keyhole Endoscopic-Assisted Transcervical Approach to the Upper and Middle Retrostyloid Parapharyngeal Space: An Anatomic Feasibility Study

Objectives The aim of this study was to describe the anatomical nuances, feasibility, limitations, and surgical exposure of the parapharyngeal space (PPS) through a novel minimally invasive keyhole endoscopic-assisted transcervical approach (MIKET).

Design Descriptive cadaveric study.

Setting Microscopic and endoscopic high-quality images were taken comparing the MIKET approach with a conventional combined transmastoid infralabyrinthine transcervical approach.

Participants Five colored latex-injected specimens (10 sides).

Main Outcome Measures Qualitative anatomical descriptions in four surgical stages; quantitative and semiquantitative evaluation of relevant landmarks.

Results A 5 cm long inverted hockey stick incision was designed to access a corridor posterior to the parotid gland after independent mobilization of nuchal and cervical muscles to expose the retrostyloid PPS. The digastric branch of the facial nerve, which runs 16.5 mm over the anteromedial part of the posterior belly of the digastric muscle before piercing the parotid fascia, was used as a landmark to identify the main trunk of the facial nerve. MIKET corridor was superior to the crossing of the accessory nerve over the internal jugular vein within 17.3 mm from the jugular process. Further exposure of the occipital condyle, vertebral artery, and the jugular bulb was achieved.

Conclusion The novel MIKET approach provides in the cadaver straightforward access to the upper and middle retrostyloid PPS through a natural corridor without injuring important neurovascular structures. Our work sets the anatomical nuances and limitations that should guide future clinical studies to prove its efficacy and safety either as a stand-alone procedure or as an adjunct to other approaches, such as the endonasal endoscopic approach.

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.

Fine needle aspiration is a suitable diagnostic modality for parotid tumors but has important limitations.

Extracapsular dissection is safe and effective for small superficial tumors away from the facial nerve.

Nerve monitoring may reduce temporary facial weakness but does not replace robust surgical technique.

Outpatient parotidectomy is safe and feasible for appropriately selected patients.

Prospective Assessment of Intraoperative Facial Nerve Monitoring in Patients Undergoing Partial Parotidectomy

The most significant complication of parotid gland tumor surgery is facial weakness. This study compares the occurrence of transient facial palsy in patients with parotid gland tumors who underwent surgery without monitoring to those who underwent surgery with monitoring. The study’s aim was to investigate facial nerve function in patients undergoing parotidectomy as well as the effect of intraoperative facial nerve monitoring and the effect of certain risk factors on the surgery and onset of postoperative facial palsy. This prospective study included 100 patients who underwent parotidectomy. The study cohort was divided into two groups. Group I included 50 patients who underwent surgery without neuromonitoring and group II included 50 patients who underwent surgery with neuromonitoring. The neurological assessment was conducted using the House–Brackmann scale. Preoperatively and one month postoperatively, electroneuronography (ENoG) and blink reflex tests were done. The analyses showed a significant reduction of the compound muscle action potential (CMAP) amplitude of the orbicularis oculi and orbicularis oris muscles and prolonged R1 and R2 blink reflex latencies 1 month after surgery. On neurological and electrophysiological studies, the rate of postoperative transient facial nerve dysfunction was significantly different between the groups. Significantly more patients, operated with use of facial nerve monitoring, presented postoperatively normal nerve function (i.e., House–Brackmann grade I) compared to those who underwent surgery without monitoring (78% and 26%, respectively; $p<0.001$ ). Monitoring had a statistically significant impact on the prevalence of facial nerve conduction disorders in patients who underwent surgery, according to the blink reflex and ENoG studies. The duration of the surgical procedure was not affected by monitoring in any way. The clinical evaluation of facial nerve function (House–Brackmann scale) and some ENoG results 1 month after surgery were found to have a significant correlation. To summarize, using monitoring considerably reduced the negative impact of local factors and the prevalence of transient facial nerve palsy.

The potential applicability of facial nerve monitoring as a navigation tool in parotid gland surgery

OBJECTIVES

The aim of this study was to assess the relationship between the stimulation amplitude and the distance to the facial nerve.

METHODS

This study was designed as a prospective clinical study. A total of 20 patients (12 males, 8 females) were included. Partial superficial parotidectomy was performed in all patients with intraoperative facial monitoring. Measurements were made on the main trunk and major branches. Stimulation was started at 1 mA and incrementally increased to 2 and 3 mA's. The shortest distance creating a robust response (>100 mV) was recorded.

RESULTS

At 1 mA, 2 mA and 3 mA stimulation intensity, the average distance between the tip of the stimulation probe and the main trunk was 2.20 ± 0.76 mm (range 1-3 mm), 3.80 ± 0.95 mm (range 2-5 mm), 4.80 ± 1.05 mm (range 3-7 mm) respectively. The stimulus intensity was inversely proportional in respect to the distance between the nerve and the tip of the stimulus probe (P < .00). The same relation was present in the facial nerve major branch measurements (P < .00).

CONCLUSION

The proportional stimulation amplitude and distance to the facial nerve is thought to be a reliable auxillary method to assist the surgeon by facilitating the estimation of the distance to the facial nerve during extracapsular dissection and minimally invasive cases where the facial nerve isn't routinely dissected.

LEVEL OF EVIDENCE

Level 3.

An institutional review of recurrent pleomorphic adenoma of the parotid gland

OBJECTIVE

Surgical resection is standard treatment for pleomorphic adenoma (PA) of the parotid gland. A small number (2-5%) of these tumors recur. Recurrence usually necessitates reoperation, which is technically challenging and puts the facial nerve (FN) at risk. The aim of this study is to characterize the recurrent parotid PA population and compare outcomes after surgery for singly recurrent and multiply recurrent tumors.

METHODS

This study was a retrospective chart review of patients at a single tertiary care academic medical center who underwent operations for recurrent PA of the parotid gland between 2007 and 2020. Demographic data, details of surgical interventions, pre- and postoperative FN function, and recurrence rates were studied. These factors were compared between patients with singly and multiply recurrent tumors.

RESULTS

Thirty-eight patients met criteria: 4 patients presented for primary PA and subsequently recurred, 26 with a first recurrence, 7 with a second recurrence, and 1 with a fourth recurrence. Multiply recurrent PAs were more likely to require at least partial nerve sacrifice at the time of reoperation (P = 0.0092). Significantly worse long-term FN outcomes were seen following surgery for multiply recurrent PA (P = 0.008). There was no significant difference between the rate of re-recurrence following first revision surgery vs second-fourth revision surgery. Time to reoperation was significantly shorter between the first and second revision surgery than between the primary surgery and first revision (P = 0.0017).

CONCLUSION

Surgery for recurrent PA incurs high risk to the FN, and this risk appears to increase in the setting of multiple recurrences.

Endoscopic and Robotic Parotidectomy for the Treatment of Parotid Tumors: A Systematic Review and Meta-Analysis

Background

The goal of this review was to introduce endoscopic/robotic parotidectomy (EP/RP) and compare EP/RP against conventional parotidectomy (CP) regarding the intraoperative and postoperative parameters in the treatment of parotid tumors.

Methods

A systematic literature search of medical databases (PubMed, Embase, and Cochrane Central Register of Controlled Trials) was performed from inception to November 2020 to generate relevant studies.

Results

A total of 13 eligible studies (572 patients) were included for systematic review, and 7 out of 13 comparable studies for the quantitative synthesis of outcomes. Patients who underwent EP were characterized by less intraoperative bleeding volume, shorter incision length, and higher satisfaction postoperatively (WMD, 95% CI, -42.80; - 58.23 to -27.37; p < 0.01; WMD, 95% CI, -5.64; -7.88 to -3.39; p < 0.01; SMD, 95% CI, 1.88; 1.46 to 2.31; p < 0.01, respectively). However, operative time and risk of facial palsy exhibited no significant differences (WMD, 95% CI, -11.17; -26.71 to 4.34; p = 0.16; OR, 95% CI,0.71; 0.39 to 1.32; p = 0.28, respectively).

Conclusions

Our findings suggest that the current evidence does not adequately support EP is equally safe and effective as CP. In certain selected cases, endoscopic technology has its unique advantages. For patients with strong cosmetic needs, endoscopic or robotic techniques may be an alternative through adequate preoperative evaluations.

Systematic Review Registration

International Prospective Register of Systematic Reviews, identifier CRD42020210299.

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.

Ear, Nose, and Throat Surgery: Postoperative Complications After Selected Head and Neck Operations

Unanticipated complications of ENT surgeries may have profound functional and esthetic consequences for patients. Herein, we provide a broad overview of postoperative complications after ENT surgery, illustrating their unique nature, impact, and principles of management. The discussion is organized by subspecialty to highlight the great anatomic complexity of the head and neck and the importance of critical neurovascular and sensory structures that make ENT an impactful, yet challenging surgical specialty.

[Surgical Management of Salivary Gland Carcinoma]

Salivary gland carcinomas are very threatening diseases. The patient's survival depends to a large extent on planning and performing the resection. This article provides assistance with the most important surgical decisions. Using illustrative examples and practical tips the article shows how oncological salivary gland surgery can be successful.

Indications for Facial Nerve Monitoring During Parotidectomy

Facial nerve injury is the most feared complication during parotid surgery. Intraoperative electromyographic nerve monitoring can be used to identify the facial nerve, map its course, identify surgical maneuvers detrimental to the nerve, and provide prognostic information. Data regarding outcomes with facial nerve monitoring are heterogeneous. In contrast, the incidence of permanent weakness has not been shown to be significantly affected by use of nerve monitoring. For revision surgery, studies show that monitored patients had (1) weakness that was less severe with quicker recovery and (2) shorter operative times compared with unmonitored patients.

Assessment of Intraoperative Nerve Monitoring Parameters Associated With Facial Nerve Outcome in Parotidectomy for Benign Disease

Importance

Prior studies suggest that the use of facial nerve monitoring decreases the rate of immediate postoperative facial nerve weakness in parotid surgery, but published data are lacking on normative values for these parameters or cutoff values to prognosticate facial nerve outcomes.

Objective

To identify intraoperative facial nerve monitoring parameters associated with postoperative weakness and to evaluate cutoff values for these parameters under which normal nerve function is more likely.

Design, Setting, and Participants

This retrospective case series of 222 adult patients undergoing parotid surgery for benign disease performed with intraoperative nerve monitoring was conducted at an academic medical institution from September 13, 2004, to October 30, 2014. The data analysis was conducted from May 2018 to January 2019.

Main Outcomes and Measures

The main outcome measure was facial nerve weakness. Receiver operating characteristic curves were generated to define optimal cut point to maximize the sensitivity and specificity of the stimulation threshold, mechanical events, and spasm events associated with facial nerve weakness.

Results

Of 222 participants, 121 were women and 101 were men, with a mean (SD) age of 51 (16) years. The rate of temporary facial nerve paresis of any nerve branch was 45%, and the rate of permanent paralysis was 1.3%. The mean predissection threshold was 0.22 milliamperes (mA) (range, 0.1-0.6 mA) and the mean postdissection threshold was 0.24 mA (range, 0.08-1.0 mA). The average number of mechanical events was 9 (range, 0-66), and mean number of spontaneous spasm events was 1 (range, 0-12). Both the postdissection threshold (area under the curve [AUC], 0.69; 95% CI, 0.62-0.77) and the number of mechanical events (AUC, 0.58; 95% CI, 0.50-0.66) were associated with early postoperative facial nerve outcome. The number of spasm events was not associated with facial nerve outcome. The optimal cutoff value for the threshold was 0.25 mA, and the optimal cutoff for number of mechanical events was 8. If a threshold of greater than 0.25 mA was paired with more than 8 mechanical events, there was a 77% chance of postoperative nerve weakness. Conversely, if a threshold was 0.25 mA or less and there were 8 mechanical events or less, there was 69% chance of normal postoperative nerve function. No parameters were associated with permanent facial nerve injury.

Conclusions and Relevance

Postdissection threshold and the number of mechanical events are associated with immediate postoperative facial nerve function. Accurate prediction of facial nerve function may provide anticipatory guidance to patients and may provide surgeons with intraoperative feedback allowing adjustment in operative techniques and perioperative management.

Comparison of Parotidectomy With Observation for Treatment of Pleomorphic Adenoma in Adults

Importance

There is no consensus regarding optimal management of pleomorphic adenoma in adults.

Objectives

To compare parotidectomy with observation for the management of pleomorphic adenoma in patients 50 years or older by age.

Design and Setting

This decision analytical model was performed from November 21, 2019, to June 15, 2020, using a Markov model. Model variables and ranges were selected based on a literature review. A 1-way sensitivity analysis was performed to evaluate the age threshold at which each algorithm, either upfront elective parotidectomy or observation, would be favored. A Monte Carlo probabilistic sensitivity analysis using variable ranges was then performed 5 times with patients in the model assigned a starting age of 50, 60, 70, 80, and 90 years to assess how age at diagnosis would be associated with the model results.

Main Outcomes and Measures

Model outcomes were measured with quality-adjusted life-years (QALYs).

Results

In the study models, the age thresholds at which observation became more beneficial than parotidectomy were 88.5 years for patients with superficial lobe tumors (5.37 QALYs in favor of parotidectomy below this age, and 5.37 QALYs in favor of observation above this age) and 83.4 years for patients with deep lobe tumors (7.51 QALYs in favor of surgery below this age, and 7.51 QALYs in favor of observation above this age). There was no significant difference in outcomes between parotidectomy and observation among patients aged 70 to 80 years.

Conclusions and Relevance

This study suggests that the outcomes associated with parotidectomy and observation are similar at 70 years or older among patients with pleomorphic adenoma and that observation may be the favorable treatment in that age group.

Critical Review and Consensus Statement for Neural Monitoring in Otolaryngologic Head, Neck, and Endocrine Surgery

BACKGROUND

Enhancing patient outcomes in an array of surgical procedures in the head and neck requires the maintenance of complex regional functions through the protection of cranial nerve integrity. This review and consensus statement cover the scope of cranial nerve monitoring of all cranial nerves that are of practical importance in head, neck, and endocrine surgery except for cranial nerves VII and VIII within the temporal bone. Complete and applied understanding of neurophysiologic principles facilitates the surgeon's ability to monitor the at-risk nerve.

METHODS

The American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) identified the need for a consensus statement on cranial nerve monitoring. An AAO-HNS task force was created through soliciting experts on the subject. Relevant domains were identified, including residency education, neurophysiology, application, and various techniques for monitoring pertinent cranial nerves. A document was generated to incorporate and consolidate these domains. The panel used a modified Delphi method for consensus generation.

RESULTS

Consensus was achieved in the domains of education needs and anesthesia considerations, as well as setup, troubleshooting, and documentation. Specific cranial nerve monitoring was evaluated and reached consensus for all cranial nerves in statement 4 with the exception of the spinal accessory nerve. Although the spinal accessory nerve's value can never be marginalized, the task force did not feel that the existing literature was as robust to support a recommendation of routine monitoring of this nerve. In contrast, there is robust supporting literature cited and consensus for routine monitoring in certain procedures, such as thyroid surgery, to optimize patient outcomes.

CONCLUSIONS

The AAO-HNS Cranial Nerve Monitoring Task Force has provided a state-of-the-art review in neural monitoring in otolaryngologic head, neck, and endocrine surgery. The evidence-based review was complemented by consensus statements utilizing a modified Delphi method to prioritize key statements to enhance patient outcomes in an array of surgical procedures in the head and neck. A precise definition of what actually constitutes intraoperative nerve monitoring and its benefits have been provided.

Best Practices in Facial Nerve Monitoring

OBJECTIVES/HYPOTHESIS

Facial nerve monitoring (FNM) has evolved into a widely used adjunct for many surgical procedures along the course of the facial nerve. Even though majority opinion holds that FNM reduces the incidence of iatrogenic nerve injury, there are few if any studies yielding high-level evidence and no practice guidelines on which clinicians can rely. Instead, a review of the literature and medicolegal cases reveals significant variations in methodology, training, and clinical indications.

STUDY DESIGN

Literature review and expert opinion.

METHODS

Given the lack of standard references to serve as a resource for FNM, we assembled a multidisciplinary group of experts representing more than a century of combined monitoring experience to synthesize the literature and provide a rational basis to improve the quality of patient care during FNM.

RESULTS

Over the years, two models of monitoring have become well-established: 1) monitoring by the surgeon using a stand-alone device that provides auditory feedback of facial electromyography directly to the surgeon, and 2) a team, typically consisting of surgeon, technologist, and interpreting neurophysiologist. Regardless of the setting and the number of people involved, the reliability of monitoring depends on the integration of proper technical performance, accurate interpretation of responses, and their timely application to the surgical procedure. We describe critical steps in the technical set-up and provide a basis for context-appropriate interpretation and troubleshooting of recorded signals.

CONCLUSIONS

We trust this initial attempt to describe best practices will serve as a basis for improving the quality of patient care while reducing inappropriate variations.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:S1-S42, 2021.

Day case superficial parotidectomy-does it work?

PURPOSE

To establish if day case superficial parotidectomy is feasible, safe and does not result in excess readmissions.

METHOD

A retrospective review was carried out of all patients listed for superficial parotidectomy with day case intent by a single surgeon between January 2016 and December 2019 inclusively. The reasons for failure of same day discharge were established. Postoperative complications and readmissions were recorded. Our approach for a superficial parotidectomy typically includes the use of a 10Fr suction drain which is removed at 4 h postoperatively if the output is less than 30 ml.

RESULTS

Ninety-one consecutive superficial parotidectomies listed for day case surgery were eligible for inclusion. Seventeen patients failed to be discharged on the same day and were admitted giving a day case success rate of 81%. Most of these (n = 9) occurred in the first year of adopting day case surgery. The most common reason to admit patients was a late finish (n = 8, 47%). Six patients (25%) were admitted due to anaesthetic complications. One patient had a surgical complication requiring admission.

CONCLUSION

Our series demonstrates that day case superficial parotidectomy using a surgical drain is feasible, safe and does not result in an unacceptable readmission rate. In our experience, surgical complications are an uncommon cause for day case failure. The most common cause for day case failure was a late finish. Postoperative complications including bleeding, seroma/salivary collection and facial nerve palsy were in keeping with or better than those quoted in the literature.

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.

Intraoperative monitoring of the facial nerve during parotid gland surgery in Otolaryngology services - Head and Neck Surgery

INTRODUCTION

Facial nerve injury remains the most severe complication of parotid gland surgery. Due to the increasing evidence about the advantage of the use of intraoperative facial nerve monitoring, a survey was distributed among members of the Spanish Society of Otorhinolaryngology-Head and Neck Surgery with the objective of determining patterns of its use.

MATERIAL AND METHODS

A questionnaire which included 12 separate questions in 3 sections was distributed via email through the official email of the Spanish Society of Otorhinolaryngology-Head and Neck Surgery. The first section of questions was in relation to demographic characteristics, the second section was related to the pattern of monitoring use and the third section referred to litigation related to facial palsy.

RESULTS

1544 anonymous questionnaires were emailed. 255 surveys were returned, giving an overall response rate of 16.5%. From these, 233 (91.3%) respondents perform parotid gland surgery. Two-hundred nineteen (94%) respondents use intraoperative facial nerve monitoring. Of the respondents,94% used intraoperative facial nerve monitoring if in their current practice they performed fewer than 10 parotidectomies per year and 93.8% if they performed more than 10 (OR, 1.02; 95% CI, 0.68-1.45; p=.991). With regard to lawsuits, just 3 (1.2%) of the respondents had a history of a parotid gland surgery-associated lawsuit and in just one case the facial nerve monitor was not used.

CONCLUSION

Our data demonstrate that most otolaryngologists in Spain use intraoperative facial nerve monitoring during parotid gland surgery. Almost all of them use it to improve patient safety and consider that facial nerve monitoring should be helpful preventing inadvertent injury.

Clinicopathologic Features and Survival Trends for Acinic Cell Carcinoma of the Major Salivary Glands: A Surveillance, Epidemiology, and End Results Population Analysis

Background

We analyzed a population-based national registry to identify the most influential patient pretreatment and treatment factors affecting overall survival (OS) and cause-specific survival (CSS) in patients diagnosed with acinic cell carcinoma (ACC) of the major salivary glands.

Methods

Using the Surveillance, Epidemiology, and End Results (SEER) database of the US National Cancer Institute (NCI) related to survival, a total of 1,254 patients with diagnosed ACC of the major salivary glands from 1975 to 2016 met inclusion criteria. Factors significant for OS and CSS were determined using univariate and multivariate analysis with the Cox proportional hazards model.

Results

Univariate OS analysis demonstrated that surgery favorably influenced longer survival compared to no surgery (hazard ratio (HR) 2.35, P < 0.05). Patient age was found to be highly predictive of superior OS (divided into 10-year age bands, P < 0.0001, younger age better). In multivariate OS analysis, there were statistically significant worse outcomes for men (HR 1.54, P < 0.05), grades III/IV (HR 2.5, P < 0.05), and distant disease (HR 3.55, P < 0.05) or regional disease (HR 1.22, P < 0.05). Patients diagnosed during years 1996 - 2016 had better OS when compared to earlier decades 1975 - 1995 (HR 1.38, P < 0.05). In univariate analysis, the mean CSS for grades I, II, and III/IV were 429 months (95% confidence interval (CI), ± 38.39), 426 months (95% CI, ± 25.73) and 198 months (95% CI, ± 66.38). Multivariate analysis of CSS further demonstrated that there were statistically significant worse outcomes for men (HR 1.68, P < 0.05), grade III/IV (HR 3.2, P < 0.05), tumor size greater than 40 mm (P < 0.001), and distant disease (HR 4.48, P < 0.05) or regional disease (HR 1.84, P < 0.05).

Conclusions

To our knowledge, this is the largest population-based study of OS and CSS of major salivary gland ACC. We found that the patient pretreatment and treatment factors including younger age at diagnosis, female sex, early stage, lower grade, surgical excision, and recent year of diagnosis are associated with improved survival in patients diagnosed with ACC of the major salivary glands. We hope that this information will aid in construction of further research projects that better refine optimal treatment protocol of individualized patient care.

Effectiveness of intraoperative facial nerve monitoring and risk factors related to postoperative facial nerve paralysis in patients with benign parotid tumors: A 20-year study with 902 patients

OBJECTIVE

We examined the incidence, risk factors, and recovery time for postoperative facial nerve paralysis in patients with benign parotid tumors and also investigated the usefulness of intraoperative facial nerve monitoring (FNM).

METHODS

Subjects were 902 patients with benign parotid tumors. Univariate and multivariate analyses were conducted for risk factors of postoperative facial nerve paralysis. We investigated the relationship between intraoperative FNM and postoperative facial nerve paralysis, and the recovery time for postoperative facial nerve paralysis according to tumor site.

RESULTS

Postoperative facial nerve paralysis occurred in 179 (19.8%) of 902 patients. Among them, 15.1%, 15.8%, and 37.5% had tumors in the superficial lobe, lower pole, and deep lobe, respectively. Paralysis risk factors were deep tumors, large tumors, long operation times, extensive bleeding, and non-use of FNM. Multivariate analysis determined female patients, deep tumors, and long operation times as significant risk factors, and female patients and deep tumors had an odds ratio of nearly 2. Use of intraoperative FNM resulted in a significantly lower incidence of facial nerve paralysis and was particularly useful in patients with superficial lobe tumors. Time to recovery from facial nerve paralysis was 6 months in 88% of the patients.

CONCLUSION

The incidence of paralysis should be kept as low as possible to enhance the postoperative quality of life of patients. The use of intraoperative FNM significantly lowered the incidence of paralysis in female patients with superficial tumors.

Continuous intraoperative neuromonitoring (cIONM) in head and neck surgery-a review

Although the history of intraoperative neuromonitoring (IONM) dates back to the 19th century, the method did not evolve further than the mere differentiation of nerves until recently. Only the development of continuous IONM (cIONM) has allowed for non-stop analysis of excitation amplitude and latency during surgical procedures, which is nowadays integrated into the software of almost all commercially available neuromonitoring devices. The objective of cIONM is real-time monitoring of nerve status in order to recognize and prevent impending nerve injury and predict postoperative nerve function. Despite some drawbacks such as false-positive/negative alarms, technical artefacts, and rare adverse effects, cIONM remains a good instrument which is still under development. Active (acIONM) and passive (pcIONM) methods of cIONM are described in literature. The main fields of cIONM implementation are currently thyroid surgery (in which the vagal nerve is continuously stimulated) and surgery to the cerebellopontine angle (in which the facial nerve is either continuously stimulated or the discharge signal of the nerve is analyzed via pcIONM). In the latter surgery, continuous monitoring of the cochlear nerve is also established.

Factors associated with facial weakness following surgery for benign parotid disease: a retrospective multicenter study

BACKGROUND

Facial nerve weakness is the most common and most concerning complication after parotidectomy. Risk factors for this complication following surgery for benign diseases remain controversial.

OBJECTIVE

Review the frequency and prognosis of facial nerve weakness after parotidectomy and analyze potential risk factors.

DESIGN

Retrospective review of medical records.

SETTINGS

Two tertiary care centers.

PATIENTS AND METHODS

We included all parotidectomies performed for benign diseases from January 2006 to December 2018. Details about the development and recovery of postoperative facial weakness were recorded. Patient, disease and surgery-related variables were analyzed using bivariate and multivariate analyses to identify risk factors.

MAIN OUTCOME MEASURES

Frequency, recovery rates and risk factors for facial nerve weakness SAMPLE SIZE: 191 parotidectomies, 183 patients, 61 patients with facial weakness.

RESULTS

The frequency of postoperative facial weakness was 31.9% (61/191 parotidectomies). Among patients with temporary weakness, 90% regained normal facial movement within 6 months. Steroid therapy was not associated with a faster recovery. Postoperative weakness was not associated with age, diabetes, smoking, disease location, use of an intraoperative facial nerve monitor or direction of facial nerve dissection. Risk factors for temporary weakness were total parotidectomy and surgical specimens larger than 60 cubic centimeters. Revision surgery was the only identified risk factor for permanent weakness.

CONCLUSION

Larger parotid resections increase the risk of temporary facial nerve weakness while permanent weakness is mainly influenced by previous surgeries.

LIMITATIONS

Retrospective nature, underpowered sample size, selection bias associated with tertiary care cases.

CONFLICT OF INTEREST

None.

Minor Parotidectomy Complications: A Systematic Review

OBJECTIVES

To report descriptive statistics for minor parotidectomy complications.

METHODS

A systematic review was performed, selecting 235 studies for analysis. The incidence of complications was tabulated, and descriptive statistics calculated. Outlier studies, 1 standard deviation above the mean, were reexamined to determine potential causal factors for each complication. All studies were examined for statistically significant differences for any potential causal factor.

RESULTS

The pooled incidence of minor complications reported were hematoma 2.9% (95% confidence interval [CI]: 2.4-3.5), wound infection 2.3% (95% CI: 1.8-2.9), sialocele 4.5% (95% CI: 3.5-5.7), salivary fistula 3.1% (95% CI: 2.6-3.7), flap necrosis 1.7% (95% CI: 1.1-2.5), scar issues 3.6% (95% CI: 2.4-5.4), numbness 33.9% (95% CI: 25.6-43.4), and deformity 11.8 (95% CI: 6.9-19.5). Implants result in more wound complications, such as hematoma, sialocele, or salivary fistula. Sialocele and salivary fistula appear more frequently after less extensive parotid surgery, whereas hematoma, wound infections, flap necrosis, and aesthetic considerations are worse with more extensive resections.

CONCLUSIONS

Minor parotidectomy complications are more frequent than generally assumed and related to certain factors that should be investigated. Laryngoscope, 131:571-579, 2021.

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

INTRODUCTION

Facial nerve injury remains the most severe complication of parotid gland surgery. However, the use of intraoperative facial nerve monitoring (IFNM) during parotid gland surgery among Otolaryngologist-Head and Neck Surgeons continues to be a matter of debate.

MATERIALS AND METHODS

A systematic review and meta-analysis of the literature was conducted including articles from 1970 to 2019 to try to determine the effectiveness of intraoperative facial nerve monitoring in preventing immediate and permanent postoperative facial nerve weakness in patients undergoing primary parotidectomy. Acceptable studies included controlled series that evaluated facial nerve function following primary parotidectomy with or without intraoperative facial nerve monitoring.

RESULTS

Ten articles met inclusion criteria, with a total of 1069 patients included in the final meta-analysis. The incidence of immediate and permanent postoperative weakness following parotidectomy was significantly lower in the IFNM group compared to the unmonitored group (23.4% vs. 38.4%; p = 0.001) and (5.7% vs. 13.6%; p = 0.001) when all studies were included. However, when we analyze just prospective data, we are not able to find any significant difference.

CONCLUSION

Our study suggests that IFNM may decrease the risk of immediate post-operative and permanent facial nerve weakness in primary parotid gland surgery. However, due to the low evidence level, additional prospective-randomized trials are needed to determine if these results can be translated into improved surgical safety and improved patient satisfaction.

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.

Reducing the morbidity of parotidectomy for benign pathology

BACKGROUND

Conservative surgical approaches, reconstructive techniques and technology are increasingly used in parotid surgery. The aim of this study was to determine the surgeon-modifiable factors which impact the rates of post-operative complications following parotidectomy for benign pathology.

METHODS

A retrospective cohort study of patients undergoing parotidectomy for benign pathology by or under the supervision of the senior author between 2006 and 2019 was performed. Clinicopathological variables, operative techniques and post-operative complications were recorded using standardized templates. Multivariable logistic regression models were used to obtain odds ratios (ORs) whilst adjusting for the effect of other clinically relevant covariates.

RESULTS

In total, 357 parotidectomies were performed. Independent factors associated with post-operative facial paresis were re-operative surgery (OR 3.51, 95% CI 1.19-10.33, P = 0.023), nerve integrity monitoring (OR 0.50, 95% CI 0.26-0.99, P = 0.046) and operation type, with focused tumour dissection (FTD) having the lowest rate of paresis (OR 0.19, 95% CI 0.040-0.92, P = 0.038) compared to limited parotidectomy. Factors associated with reduced wound complications on adjusted analysis were dermofat grafting (OR 0.10, 95% CI 0.01-0.72, P = 0.023), lesion size (OR 0.68, 95% CI 0.50-0.92, P = 0.01) and FTD (OR 0.16, 95% CI 0.05-0.59, P = 0.005) compared to limited parotidectomy.

CONCLUSION

FTD, nerve integrity monitoring and dermofat grafting are surgeon-modifiable variables associated with lower rates of post-operative complications following parotidectomy for benign pathology. However, the benefit of these operative techniques relies on their appropriate utilization by performing surgeons.