Intraoperative Facial Monitoring Research Articles

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 45.7yr (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.

A sampling survey of intraoperative facial nerve monitoring in China

Objective: This study aims to investigate the current application and the level of knowledge of intraoperative facial nerve monitoring among medical staff in China. Methods: A comprehensive online questionnaire was conducted among medical professionals across different regions in China from October 2022 to February 2023. The survey exclusively targeted departments specializing in otolaryngology, head and neck surgery, neurosurgery, and oral and maxillofacial surgery. The questionnaire covered various aspects including general information, intraoperative facial nerve monitoring practices, training history, indications for monitoring, parameters used during monitoring procedures, as well as factors influencing its implementation. Results: A total of 417 participants from 31 provincial, municipal, and autonomous regions were included. Intraoperative facial nerve monitoring was found to be implemented in 227 (54.4%,227/417) repondents of 53 institutions (24.9%, 53/213). The top three indications for implementing this technique were acoustic neuroma, parotid gland surgery, and modified middle ear surgery (mastoidectomy). Herein 81.1%(184/227) medical staff involved in intraoperative facial nerve monitoring had received relevant training, 57.3%(130/227)-92.1%(209/227) reported a lack of clear description regarding recording thresholds, stimulation currents/frequencies/wave widths. Conclusion: The majority of the institutions surveyed have not yet adopted intraoperative facial nerve monitoring. Furthermore, significant gaps concerning the procedure exist. It is imperative to establish standards or guidelines to promote its better development and application.

Expert consensus on intraoperative facial nerve monitoring

Expert consensus on intraoperative facial nerve monitoring

Iatrogenic Facial Nerve Injury in Head and Neck Surgery in the Presence of Intraoperative Facial Nerve Monitoring With Electromyography: A Systematic Review

Iatrogenic Facial Nerve Injury in Head and Neck Surgery in the Presence of Intraoperative Facial Nerve Monitoring With Electromyography: A Systematic Review

The Outcomes of Superficial Parotidectomy with Intraoperative Facial Nerve Monitoring: Experience in Sawanpracharak Hospital 2020 to 2022

Objective: To determine the outcomes of patients undergone parotidectomy with or without facial nerve monitoring. Materials and Methods: The present study was a retrospective study that included 35 patients underwent superficial parotidectomy with pathologic findings of benign parotid tumor. The patients were divided into two groups. Intraoperative facial nerve monitoring was performed in 15 patients and did not monitor in 20 patients. Data were compared between the surgical groups with intraoperative facial nerve monitoring and the groups without intraoperative facial nerve monitoring using the chi-square test and independent t-test. Results: Patients who underwent parotidectomy between January 1, 2020 and December 31, 2022, whose pathologic findings were benign, a total of 35 cases were divided into 15 patients underwent surgery with intraoperative facial nerve monitoring and 20 patients underwent surgery without intraoperative facial nerve monitoring. There was no statistical difference in operation time and saliva leakage. However, there was a statistical difference in intraoperative blood loss, postoperative facial nerve weakness rate, and postoperative earlobe numbness. Conclusion: The most common complication of parotidectomy is paralysis of the facial nerve. The present study showed that intraoperative facial nerve monitoring can reduce facial nerve paralysis, blood loss during surgery and postoperative earlobe numbness. Keywords: Intraoperative facial nerve monitoring; Parotidectomy; Parotid tumor

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

The aim of this study was to assess the relationship between the stimulation amplitude and the distance to the facial nerve. 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. 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). 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 3.

The role for cochlear implants in microtia and congenital aural atresia: A case report and a review of literature

Sensorineural hearing loss resulting from microtia and aural atresia is rare due to different embryologic origins of the external and inner ear. Consequently, cochlear implants are seldom performed in patients with microtia and/or aural atresia. Herein we discuss an 8 year-old boy with congenital aural atresia and microtia who underwent cochlear implant surgery for profound hearing loss with good results. A literature review was performed and discussed. Pre-operative planning with high resolution computed tomography and facial nerve monitoring are crucial in identification and preservation of the facial nerve due to the high rate of aberrant anatomy. Careful incision placement is required particularly if pinna reconstruction is considered. Literature review highlighted various surgical approaches as well as different modalities used for intra-operative facial nerve monitoring. Only one patient had intra-operative complications. Cochlear implant is a viable solution in patients with external ear malformations and severe-profound sensorineural hearing loss. Adequate planning and counselling are essential due to the challenges that may occur in microtia and aural atresia.

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

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. 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. There was a mean age of 54.2 ± 17.8years, 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 ± 2.53months. 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. In the present study, IFNM and the existence of a benign lesion have been shown to be associated with lower severity of FND.

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.

Case Report: Extensive Temporal Bone Invasion in a Giant Vestibular Schwannoma

BackgroundRare giant vestibular schwannomas (GVSs) invade the temporal bone extensively, which carries unique risks for surgery owing to their complicated relationship with adjacent structures, difficult dissection of the temporal bone, and high risk of complications. The underlying mechanism of this invasive behavior remains unknown.Case descriptionWe report on a 28-year-old woman who presented with typical hearing loss and facial paralysis (House-Brackmann II). Magnetic resonance imaging exhibited a giant mass (∼5.0 cm) in the right cerebellopontine angle (CPA), petrous apex, and middle cranial fossa. Her primary diagnosis was GVS with petrous apex invasion. With the aid of presurgical imaging reconstruction and intraoperative facial nerve monitoring, we adopted a sequential therapeutic strategy, which included microsurgery for the CPA lesion followed by gamma knife radiosurgery (GKRS) for the petrous mass. During follow-up, stable tumor control was achieved with functional preservation of the facial nerve and no other complications. The postoperative immunohistochemical examination demonstrated dramatic intratumoral inflammation, which suggested its potential role in bony erosion. We reviewed the literature of large vestibular schwannoma with a petrous invasion and further discussed its treatment.ConclusionMicrosurgery remains the top therapeutic strategy for GVS. However, gross total resection with functional preservation of cranial nerves is challenging to achieve once the temporal bone is involved. In this case, we applied a planned and sequential approach of microsurgery and GKRS with a promising outcome, which highlighted this combinational strategy in this rare situation. In addition, pathological examination suggested that intratumoral inflammation might play a role in the bony erosion of GVS. Longer observation and more cases are needed to further investigate its molecular mechanism and treatment plan.

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.

Vestibular Nerve Section via Middle Cranial Fossa Approach.

Vestibular nerve section (VNS) is a surgical intervention with hearing preservation used for the treatment of Menière's disease after conservative medical therapy has failed (1,2). With the recent rise in less invasive treatments such as intratympanic gentamicin, VNS has been performed less frequently (3). The middle cranial fossa (MCF) approach for VNS is an uncommon approach due to its technical difficulty. However, it can provide the best distinction of internal auditory canal contents compared with retrosigmoid and retrolabyrinthine approaches. Several advancements in the MCF approach have been described, including the use of intraoperative facial nerve monitoring with electromyography, early removal of the temporal lobe retractor, and the use of an ultrasonic bone aspirator for internal auditory canal decompression (4-6). We demonstrate a case study with a step-by-step approach to successfully sectioning the superior and inferior vestibular nerves while utilizing these advancements and avoiding facial and cochlear nerve injury via the MCF (7). SDC video link: http://links.lww.com/MAO/B409.

Clinical Benefits of Facial Nerve Monitoring during Cerebellopontine Angle Surgery

Background: The surgery of cerebellopontine angle tumours has remarkably progressed over the last 2 decades due to improved microsurgical techniques. The primary operative goals are microscopic total removal of the tumour while securing the adjacent cranial nerves. Facial Nerve plays a critical role in facial muscles function and one’s cosmetic appearance, and its weakness can have profound implications on a patient’s quality of life. Aim of the Study: To assess the impact of monitoring techniques on the preservation of facial nerve function during cerebellopontine angle tumours surgery. Patients and Methods: This is a prospective study. This study was conducted on 30 cases (2 groups, each had 15 patients) with CPA lesions that had undergone surgical excision of these lesions performed by retrosigmoid approach (Group A: the patients were operated under continuous intraoperative facial nerve monitoring (IOFNM) and Group B: the patients were operated without IOFNM). They were operated upon in neurosurgery departments at Al-Azhar university hospitals between August 2019 and August 2021. Results: This study showed that excellent facial nerve function (HB Grade I and II) was higher in group A than group B, immediately and at 6-month post op (80% and 93% VS 53.3% and 66.7%). Intermediate (HB Grade III and VI) and Poor (HB Grade V and VI) facial nerve function was higher in group B than group A; both immediately and 6-month postop (46.7% and 33.3% VS 20% and 6.6%). However, no statistically significant P-Value between both groups. Conclusion: We concluded that IOFNM can help, but cannot guarantee, the preservation of facial nerve. Furthermore, it is merely a technical adjunct and does not replace surgical skills, knowledge of anatomy and experience.

SBCCP course - Qualification for mapping of cranial nerves in head and neck surgery - intraoperative facial nerve monitoring

SBCCP course - Qualification for mapping of cranial nerves in head and neck surgery - intraoperative facial nerve monitoring

Intraoperative facial nerve monitoring in parotid surgery

Intraoperative facial nerve monitoring in parotid surgery

Preoperative Facial Nerve Palsy in Patients With Vestibular Schwannoma: Clinical Features and Postoperative Functional Prognosis in a Case Series of 34 Among 1228 Consecutive Patients.

Facial nerve palsy is a rare presenting symptom of vestibular schwannomas and has not been investigated in detail. To investigate the incidence, clinical features, and postoperative long-term outcomes of facial nerve function in patients with vestibular schwannomas causing preoperative facial nerve palsy. After excluding patients with neurofibromatosis type 2 and those with prior treatment, 1228 consecutive patients who underwent vestibular schwannoma surgery were retrospectively investigated. Patients with and without preoperative facial nerve palsy were compared statistically to clarify their clinical features. Preoperative tumoral facial nerve palsy was seen in 34 patients (2.8%). Their clinical features included older age, having large cystic tumors with significant meatal extension, and showing abnormal electrogustometric responses, compared with patients without preoperative facial nerve palsy. Owing to the frequent insufficient intraoperative responses on facial nerve electromyography, the tumor resection rate was lower in the group with preoperative facial nerve palsy (mean: 95.2%). Among the 33 patients with sufficient follow-up data (mean: 63.9 mo), additional treatment was required only in 1 patient and facial nerve function improved in 25 patients (75.8%) within 2 yr postoperatively. Facial nerve palsy is a rare preoperative symptom that occurs in less than 3% of patients with vestibular schwannoma. Tumor resection in such patients tends to be challenging owing to their advanced age, having large cystic tumors with significant meatal extension, and difficulties in intraoperative facial nerve monitoring, but surgical decompression of the facial nerve can assist in the improvement of their long-term functions.

English

BACKGROUND Salivary gland diseases are rare but an important group of disorders. Following surgeries involving the parotid gland, facial nerve paresis is a common postoperative complication. The reported worldwide incidence of facial nerve paresis following parotidectomy is approximately 20 - 60 %. We need to determine the incidence of facial nerve paresis in the post-operative period following superficial, adequate, or extra-capsular parotidectomy of benign parotid tumours with the use of intraoperative facial nerve monitoring. METHODS A non-randomised interventional trial was initiated once cleared by the institutional review board. With the calculated sample size of 44, the patients underwent nervemonitoring for the identification of the branches of the facial nerve. Clinical grading of the nerve function was done using the House-Brackmann score on the postoperative days 2, 7, and 60. The findings were compared with the historical controls (HC) of 53 patients who underwent similar procedures but with no intraoperative facial nerve monitoring. All patients were recruited in continuity for over two years. RESULTS The incidence of facial nerve paresis was 30 - 40 % and 10 - 20 % in the historical control and nerve monitoring group, respectively (P = 0.07). The duration of surgery in the nerve monitoring group was 83 ± 30 minutes and 95 ± 15 minutes in the HC group. The incidence of nerve paresis was similar among the trainees and consultants suggestive of adequate training. CONCLUSIONS Intraoperative facial nerve monitoring is a useful adjunct to reduce the incidence of early postoperative facial nerve paresis. The technique would not prolong the duration of the procedure. The technique may be utilized safely on a routine basis even during surgical training. KEYWORDS Facial Nerve Monitoring, Parotidectomy, Benign Parotid Tumour, HouseBrackmann Score

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

IntroductionFacial 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 methodsA 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. Results1544 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. ConclusionOur 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.

Optimizing Location of Subdermal Recording Electrodes for Intraoperative Facial Nerve Monitoring

The purpose of this study is to determine if different facial muscle groups demonstrate different responses to facial nerve stimulation, the results of which could potentially improve intraoperative facial nerve monitoring (IOFNM). IOFNM data were prospectively collected from patients undergoing cochlear implantation. At different stages of nerve exposure, three sites were stimulated using a monopolar pulse. Peak electromyography (EMG) amplitude (μV) in four muscle groups innervated by four different branches of the facial nerve (frontalis-temporal, inferior orbicularis oculi-zygomatic, superior oribularis oris-buccal, and mentalis-marginal mandibular) were recorded. A total of 279 peak EMG amplitudes were recorded in 93 patients. At all three stimulating sites, the zygomatic branch mean peak EMG amplitudes were statistically greater than those of the temporal, buccal, and marginal mandibular branches (P< .05). At stimulating Site C, the marginal mandibular branch mean peak EMG was stronger than the temporal or buccal branches (P< .05). Of the 279 stimulations, the zygomatic branch demonstrated the highest amplitude in 128 (45.9%) trials, followed by the marginal mandibular branch (22.2%). When utilized, IOFNM should be performed with at least two electrodes, one of which is placed in the orbicularis oculi muscles and the other in the mentalis muscle. However, there is wide variability between patients. As such, in cases of suspected variant nerve anatomy or increased risk of injury (intradural procedures), surgeons should consider using more than two recording electrodes, with at least one in the orbicularis oculi muscle. 3 Laryngoscope, 131:E2329-E2334, 2021.

Machine Learning Models for Predicting Facial Nerve Palsy in Parotid Gland Surgery for Benign Tumors

BackgroundDespite the increasing use of intraoperative facial nerve monitoring during parotid gland surgery (PGS) and the improvement in the preoperative radiological assessment, facial nerve injury (FNI) remains the most severe complication after PGS. Until now, no studies have been published regarding the application of machine learning (ML) for predicting FNI after PGS. We hypothesize that ML would improve the prediction of patients at risk. MethodsPatients who underwent PGS for benign tumors between June 2010 and June 2019 were included. ResultsRegarding prediction accuracy and performance of each ML algorithm, the K-nearest neighbor and the random forest achieved the highest sensitivity, specificity, positive predictive value, negative predictive value F-score, receiver operating characteristic (ROC)–area under the ROC curve, and accuracy globally. The K-nearest neighbor algorithm achieved performance values above 0.9 for specificity, negative predictive value, F-score and ROC–area under the ROC curve, and the highest sensitivity and positive predictive value. ConclusionsThis study demonstrates that ML prediction models can provide evidence-based predictions about the risk of FNI to otolaryngologists and patients. It is hoped that such algorithms, which use clinical, radiological, histological, and cytological information, can improve the information given to patients before surgery so that they can be better informed of any potential complications.