Patterns of Use of Facial Nerve Monitoring During Parotid Gland Surgery

Head and Neck Vascular Anomalies in Children

Craniomaxillofacial vascular anomalies encompass a diverse and complex set of pathologies that may have a profound impact on pediatric patients. They are subdivided into vascular tumors and vascular malformations depending on biological properties, clinical course, and distribution patterns. Given the complexity and potential for leading to significant functional morbidity and esthetic concerns, a multidisciplinary approach is generally necessary to optimize patient outcomes. This article reviews the etiology, clinical course, diagnosis, and current management practices related to vascular anomalies in the head and neck.

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

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

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.

Applying Tumescent solution for preserving the facial nerve in parotidectomy

BACKGROUND

Facial nerve palsy is one of the most common complications in parotid gland surgery. This report evaluates the effectiveness of applying Tumescent solution for preserving the facial nerve in parotidectomy.

MATERIAL AND METHODS

Prospective and descriptive clinical study on 34 patients undergoing parotidectomy with facial nerve preservation. Before skin incision, 5-10 min, we injected 100-200 ml of the Tumescent solution into the surgical area. We recorded the surgical method, tumor size, length of surgery, pathological results and facial nerve dysfunction. All patients were followed for a period ranging from 6 to 24 months.

RESULTS

There were 14 patients with malignant tumors and 20 patients with benign tumors. The length of surgery lasted from 90 to 180 min, with an average of 126.8 min. The number of patients having temporary facial paralysis was 22 cases (64.7%), recovery time ranged from 1 week to 6 months, and no permanent facial paralysis cases were recorded. The clinical occurrence of Frey's syndrome was five cases (14.7%).

CONCLUSIONS

The application of Tumescent solution for preserving facial nerves in parotidectomy could minimize nerve injury and shorten the length of surgery.

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.

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.

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.

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.

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.

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.

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.

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.

Feasibility of Brachial Plexus Schwannoma Enucleation With Intraoperative Neuromonitoring

Objectives

To evaluate the feasibility of brachial plexus schwannoma enucleation under intraoperative neuromonitoring.

Methods

Five patients who were treated for brachial plexus schwannoma under intraoperative neuromonitoring from 2008 to 2018 were included in this retrospective review. Neuromonitoring was performed with a 100-μV event threshold of the neuromonitoring system (NIM-2 or 3) at the deltoid, biceps brachii, triceps brachii, and brachioradialis muscles. Patient characteristics, tumor size and location, intraoperative neuromonitoring findings, and postoperative function were evaluated.

Results

The intraoperative neuromonitoring findings were in accordance with the preoperative assessment of the included nerve root. Three patients had no postoperative morbidity, one patient had temporary paresthesia of the forearm for 2 months, and one patient mild loss of grip strength for 1 month.

Conclusion

Intraoperative neuromonitoring of the arm and forearm muscles during enucleation of brachial plexus schwannoma promoted confident and successful surgery with minimal postoperative morbidity.

[Continuous intraoperative neuromonitoring (cIONM) in head and neck surgery-a review. German version]

Obwohl die Geschichte des intraoperativen Neuromonitorings (IONM) bereits in das 19. Jahrhundert zurückdatiert werden kann, hat sich diese Methode bis vor Kurzem nicht von der reinen Differenzierung des Nervs weiterentwickelt. Erst das kontinuierliche IONM (cIONM) ermöglichte die durchgehende Analyse der Reizamplituden und -latenzen, welche mittlerweile ebenfalls in die Software gängiger Monitoringsysteme integriert wurde. Zielsetzung des cIONM ist ein Real-Time-Monitoring des Nervenstatus während des Eingriffs, um so drohende Nervenverletzung erkennen und verhindern zu können und die postoperative Funktion des Nervs vorhersehbar zu erhalten. Trotz einiger Nachteile wie falsch-positiver oder -negativer Alarme, technischer Artefakte und seltener Nebenwirkungen bleibt das cIONM ein gutes Hilfsmittel, das noch weiterentwickelt wird. In der Literatur sind sowohl aktive (acIONM) als auch passive (pcIONM) Reiz- und Ableitmethoden des cIONM beschrieben. Derzeit gängige Anwendungsgebiete des cIONM umfassen die Schilddrüsenchirurgie mit der kontinuierlichen Stimulation des N. vagus sowie die Chirurgie des Kleinhirnbrückenwinkels (KHBW) mit dem Monitoring des N. facialis; hierbei werden neben kontinuierlicher Stimulation auch die Entladungsmuster des Nervs analysiert. Des Weiteren ist in die Chirurgie des KHBW das kontinuierliche Monitoring des Hörnervs etabliert.

Facial Nerve Branching Patterns Vary With Vascular Anomalies

OBJECTIVES

At our institution, in vivo facial nerve mapping (FNM) is used during vascular anomaly (VAN) surgeries involving the facial nerve (FN) to create an FN map and prevent injury. During mapping, FN anatomy seemed to vary with VAN type. This study aimed to characterize FN branching patterns compared to published FN anatomy and VAN type.

STUDY DESIGN

Retrospective study of surgically relevant facial nerve anatomy.

METHODS

VAN patients (n = 67) with FN mapping between 2005 and 2018 were identified. Results included VAN type, FN relationship to VAN, FNM image with branch pattern, and surgical approach. A Fisher exact test compared FN relationships and surgical approach between VAN pathology, and FN branching types to published anatomical studies. MATLAB quantified FN branching with Euclidean distances and angles. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) analyzed quantitative FN patterns amongst VAN types.

RESULTS

VANs included were hemangioma, venous malformation, lymphatic malformation, and arteriovenous malformation (n = 17, 13, 25, and 3, respectively). VAN FN patterns differed from described FN anatomy (P < .001). PCA and HCA in MATLAB-quantified FN branching demonstrated no patterns associated with VAN pathology (P = .80 and P = .91, one-way analysis of variance for principle component 1 (PC1) and priniciple component 2 (PC2), respectively). FN branches were usually adherent to hemangioma or venous malformation as compared to coursing through lymphatic malformation (both P = .01, Fisher exact).

CONCLUSIONS

FN branching patterns identified through electrical stimulation differ from cadaveric dissection determined FN anatomy. This reflects the high sensitivity of neurophysiologic testing in detecting small distal FN branches. Elongated FN branches traveling through lymphatic malformation may be related to abnormal nerve patterning in these malformations.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:2708-2713, 2020.

Preoperative Facial Nerve Mapping to Plan and Guide Pediatric Facial Vascular Anomaly Resection

Importance

Facial vascular anomalies are surgical challenges due to their vascularity and facial nerve distortion. To assist facial vascular anomaly surgical treatment, presurgical percutaneous facial nerve stimulation and recording of compound motor action potentials can be used to map the facial nerve branches. During surgery, the nerve map and continuous intraoperative motor end plate potential monitoring can be used to reduce nerve injury.

Objective

To investigate if preoperative facial nerve mapping (FNM) is associated with intraoperative facial nerve injury risk and safe surgical approach options compared with standard nerve integrity monitoring (NIM).

Design, Setting, and Participants

This investigation was a historically controlled study at a tertiary vascular anomaly center in Seattle, Washington. Participants were 92 pediatric patients with facial vascular anomalies undergoing definitive anomaly surgery (from January 1, 1999, through January 1, 2015), with 2 years' follow-up. In retrospective review, a consecutive FNM patient cohort after 2005 (FNM group) was compared with a consecutive historical cohort (1999-2005) (NIM group).

Main Outcomes and Measures

Postoperative facial nerve function and selected surgical approach. For NIM and FNM comparisons, statistical analysis calculated odds ratios of nerve injury and operative approach, and time-to-event methods analyzed operative time.

Results

The NIM group had 31 patients (median age, 3.3 years [interquartile range, 2.2-11.4 years]; 20 [65%] male), and the FNM group had 61 patients (median age, 4.4 years [interquartile range, 1.5-11.0 years]; 26 [43%] male). In both groups, lymphatic malformation resection was most common (19 of 31 [61%] in the NIM group and 32 of 61 [52%] in the FNM group), and the median anomaly volumes were similar (52.4 mL; interquartile range, 12.8-183.3 mL in the NIM group and 65.4 mL; interquartile range, 18.8-180.2 mL in the FNM group). Weakness in the facial nerve branches at 2 years after surgery was more common in the NIM group (6 of 31 [19%]) compared with the FNM group (1 of 61 [2%]) (percentage difference, 17%; 95% CI, 3%-32%). Anterograde facial nerve dissection was used more in the NIM group (27 of 31 [87%]) compared with the FNM group (28 of 61 [46%]) (percentage difference, 41%; 95% CI, 24%-58%). Treatment with retrograde dissection without identification of the main trunk of the facial nerve was performed in 21 of 61 (34%) in the FNM group compared with 0 of 31 (0%) in the NIM group. Operative time was significantly shorter in the FNM group, and patients in the FNM group were more likely to complete surgery sooner (adjusted hazard ratio, 5.36; 95% CI, 2.00-14.36).

Conclusions and Relevance

Facial nerve mapping before facial vascular anomaly surgery was associated with less intraoperative facial nerve injury and shorter operative time. Mapping enabled direct identification of individual intralesional and perilesional nerve branches, reducing the need for traditional anterograde facial nerve dissection, and allowed for safe removal of some lesions after partial nerve dissection through transoral or direct excision.

Learning from Anaesthetists: A Technique for Safe and Effective Facial Nerve Monitoring

To develop a technique to reliably secure facial nerve monitoring electrodes, NeurosignTM facial nerve monitor electrodes were attached as per the manufacturer’s instructions. The electrodes were secured with ½ inch steristripsTM before connecting leads were brought to the contralateral side of the face and a single torque loop was created and secured with either more Steri-StripsTM, Micropore tapeTM, or a TegedermTM. By creating a single torque loop, a buffer between the electrode and its anchor point to the contralateral face was formed. This allowed for the secure attachment of leads from the electrodes by removing tension, thereby reducing the likelihood of displacement. We have used this technique successfully for the last three years in over 50 parotid procedures and 50 middle ear explorations. Facial nerve monitoring is an important surgical tool used in otology and head and neck surgery. Using torque loops when preparing a patient for surgery prevents the dislodgement of electrodes during operation, thereby ensuring the safety of the patient in a sometimes perilous environment.

Parotid tumours: clinical and oncologic outcomes after microscope-assisted parotidectomy with intraoperative nerve monitoring

Temporary and permanent facial nerve dysfunctions can be observed after parotidectomy for benign and malignant lesions. Intraoperative nerve monitoring is a recognised tool for the preservation of the nerve, while the efficacy of the operative microscope has been rarely stated. The authors report their experience on 198 consecutive parotidectomies performed on 196 patients with the aid of the operative microscope and intraoperative nerve monitoring. 145 parotidectomies were performed for benign lesions and 53 for malignancies. Thirteen patients treated for benign tumours experienced temporary (11 cases) or permanent facial palsy (2 cases, both of House-Brackmann grade II). Ten patients with malignant tumour presented with preoperative facial nerve weakness that did not improve after treatment. Five and 6 patients with malignant lesion without preoperative facial nerve deficit experienced postoperative temporary and permanent weakness respectively (the sacrifice of a branch of the nerve was decided intraoperatively in 2 cases). Long-term facial nerve weakness after parotidectomy for lesions not directly involving or originating from the facial nerve (n = 185) was 2.7%. Patients treated for benign tumours of the extra facial portion of the gland without inflammatory behaviour (n = 91) had 4.4% facial nerve temporary weakness rate and no permanent palsy. The combined use of the operative microscope and intraoperative nerve monitoring seems to guarantee facial nerve preservation during parotidectomy.

Phrenic nerve stimulation during neck dissection for advanced thyroid cancer involving level IV: is it worth doing it?

During thyroidectomy and neck dissection surgery for advanced or recurrent metastatic thyroid cancer under intraoperative monitoring, we used the available technology to assess the feasibility of such an intervention to monitor those patients with phrenic nerves at risk. A retrospective review of patients operated on from January 2009 to December 2015 by a single surgeon (CSD) was conducted. Patients who had neck and mediastinal dissection, with or without total thyroidectomy, due to advanced or recurrent metastatic disease to the neck were selected. The procedures were done under intraoperative nerve monitoring using nerve monitoring systems (NIM 2.0 or 3.0; Medtronic, Jacksonville, FL, USA). A total of 19 patients were included in the study, with a mean age of 57.6 years ± 16.3 and a male/female ratio of 10:9. Overall, all patients had an intact phrenic nerve at the conclusion of the surgery. One patient had an aggressive tumor that precluded sacrifice of the left recurrent laryngeal nerve and ipsilateral thoracic duct. The procedure was complicated by a temporary impairment of the diaphragm contraction with intraoperative nerve monitoring as well as a chyle fistula. This was due to the manipulation of the tissue surrounding the phrenic nerve. Intraoperative nerve monitoring of the phrenic nerve offers the surgeon a "potential" method of ensuring phrenic nerve integrity in cases of advanced thyroid cancers with gross level IV metastatic disease. Further prospective studies are needed to assess the risks of this intervention and evaluate the method of recording diaphragm contraction movement.

Facial Nerve Preservation During Giant Mandibular Tumor Surgery

Marginal mandibular branch of facial nerve is easy to be ignored and injured in patients undergoing giant mandibular tumor resections. In this article, a 30-year-old patient with a giant tumor in the left mandible, an operation of segmental mandibulectomy and reconstruction was given, and the surgery was assisted by intraoperative facial nerve monitoring. During surgery, the marginal mandibular branch of the facial nerve was detected and well preserved. The patient showed no facial function injury postoperation. In patients of giant mandibular tumor resection, the anatomic location of the facial nerve may have great changes. Preservation of marginal mandibular branch should be taken seriously. Intraoperative facial nerve monitoring is an effective method for preventing nerve weakness during such mandibular surgeries.

Improved facial nerve identification during parotidectomy with fluorescently labeled peptide

OBJECTIVES/HYPOTHESIS

Additional intraoperative guidance could reduce the risk of iatrogenic injury during parotid gland cancer surgery. We evaluated the intraoperative use of fluorescently labeled nerve binding peptide NP41 to aid facial nerve identification and preservation during parotidectomy in an orthotopic model of murine parotid gland cancer. We also quantified the accuracy of intraoperative nerve detection for surface and buried nerves in the head and neck with NP41 versus white light (WL) alone.

STUDY DESIGN

Twenty-eight mice underwent parotid gland cancer surgeries with additional fluorescence (FL) guidance versus WL reflectance (WLR) alone. Eight mice were used for additional nerve-imaging experiments.

METHODS

Twenty-eight parotid tumor-bearing mice underwent parotidectomy. Eight mice underwent imaging of both sides of the face after skin removal. Postoperative assessment of facial nerve function measured by automated whisker tracking were compared between FL guidance (n = 13) versus WL alone (n=15). In eight mice, nerve to surrounding tissue contrast was measured under FL versus WLR for all nerve branches detectable in the field of view.

RESULTS

Postoperative facial nerve function after parotid gland cancer surgery tended to be better with additional FL guidance. Fluorescent labeling significantly improved nerve to surrounding tissue contrast for both large and smaller buried nerve branches compared to WLR visualization and improved detection sensitivity and specificity.

CONCLUSIONS

NP41 FL imaging significantly aids the intraoperative identification of nerve braches otherwise nearly invisible to the naked eye. Its application in a murine model of parotid gland cancer surgery tended to improve functional preservation of the facial nerve.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:2711-2717, 2016.

Prevalence and patterns of intraoperative nerve monitoring for thyroidectomy

Objective

To estimate the patterns of use of intraoperative recurrent laryngeal nerve (RLN)-monitoring devices during thyroid surgery by otolaryngologists in the United States.

Methods

A questionnaire was mailed to 1685 randomly selected otolaryngologists, representing approximately half of all otolaryngologists currently practicing in the United States. Topics covered included training history and current practice setting, use and characteristics of use of RLN monitoring during thyroid surgery, as well as history of RLN injury and/or subsequent lawsuits. X 2 test was used to examine associations between monitor usage and dependent variables, and odds ratios calculated by logistic regression were used to refine the magnitude of these associations. RESULTS: A total of 685 (40.7%) of questionnaires were returned, and 81 percent (555) of respondents reported performing thyroidectomy. Of those, only 28.6 percent (159) reported using intraoperative monitoring for all cases. Respondents were 3.14 times more likely to currently use intraoperative monitoring if they used it during their training. Surgeons currently using intraoperative RLN monitoring during thyroidectomy were 41 percent less likely to report a history of permanent RLN injury. Further information about surgeon background and rationale for decisions regarding RLN monitor usage are discussed.

Conclusions

Presently, the majority of otolaryngologists in the United States do not report regular usage of RLN monitoring in their practices. Surgeon background and training, more so than surgical volume, significantly influenced the use of intraoperative RLN monitoring.

The Utility of Recurrent Laryngeal Nerve Monitoring During Open Pharyngeal Diverticula Procedures

OBJECTIVES

The recurrent laryngeal nerve is at risk of injury during open pharyngeal diverticula operations. The utility of recurrent laryngeal nerve (RLN) monitoring during these procedures was investigated.

METHODS

A retrospective chart review was performed of 8 open pharyngeal diverticulectomies completed between 2009 and 2014. Intraoperative RLN monitoring took place during all operations.

RESULTS

Open pharyngectomy and myotomy was successfully performed in all cases. In two cases the RLN was encountered outside of its normal course. The identity of the nerve was confirmed with electrical stimulation and normal EMG response. Vocal fold motion was preserved in all cases.

CONCLUSIONS

Use of intraoperative nerve monitoring in pharyngeal diverticula procedures may be beneficial, especially during open operations for Killian-Jamieson diverticulum (KJD) and large Zenker diverticulum (ZD), where the RLN is typically encountered outside of its normal course.

Facial Nerve Monitoring during Parotidectomy

Objectives

To determine the effectiveness of intraoperative facial nerve monitoring (FNM) in preventing immediate and permanent postoperative facial nerve weakness in patients undergoing primary parotidectomy.

Data Sources

PubMed-NCBI database from 1970 to 2014.

Review Methods

A systematic review and meta-analysis of the literature was conducted. Acceptable studies included controlled series that evaluated facial nerve function following primary parotidectomy with or without FNM (intraoperative nerve monitor vs control). Primary and secondary end points were defined as immediate postoperative and permanent facial nerve weakness (House-Brackmann score, ≥2), respectively.

Results

After a review of 1414 potential publications, 7 articles met inclusion criteria, with a total of 546 patients included in the final meta-analysis. The incidence of immediate postoperative weakness following parotidectomy was significantly lower in the FNM group compared to the unmonitored group (22.5% vs 34.9%; P = .001). The incidence of permanent weakness was not statistically different in the long term (3.9% vs 7.1%; P = .18). The number of monitored cases needed to prevent 1 incidence of immediate postoperative facial nerve weakness was 9, given an absolute risk reduction of 11.7% This corresponded to a 47% decrease in the incidence of immediate facial nerve dysfunction (odds ratio, 0.53; 95% CI, 0.35 to 0.79; P = .002).

Conclusion

In primary cases of parotidectomy, intraoperative FNM decreases the risk of immediate postoperative facial nerve weakness but does not appear to influence the final outcome of permanent facial nerve weakness.

Contemporary Changes with the Use of Facial Nerve Monitoring in Chronic Ear Surgery

Objective

There is a growing trend for the routine use of the facial nerve monitor (FNM) in chronic ear surgery. We aimed to examine current patterns in the use of FNMs in chronic ear surgery.

Study Design

Descriptive design (survey).

Setting

Academic health center.

Methods

A 10-question survey was designed to identify level of training, scope of practice, specific otologic surgeries where monitoring was most used, and the opinion of respondents regarding the use of FNMs as standard of care for chronic and/or middle ear surgery. A randomized list of 2000 board-certified members of the American Academy of Otolaryngology—Head and Neck Surgery was generated. One thousand subjects received a mailed survey with a self-addressed return envelope and 1000 subjects received an emailed survey through Surveymonkey.com .

Results

There were 359 (36%) surveys returned by mail and 258 (26%) surveys returned electronically. Forty-three percent of respondents were in private practice, and 31% were fellowship trained in otology/neurotology. Sixty-five percent used a FNM in their training and 95% had regular access to a FNM. Revision mastoid surgery, cholesteatoma, canal wall down mastoidectomy, and facial recess approach were the settings where a FNM was most used. Forty-nine percent of respondents felt that a FNM should be used as the standard of care in chronic ear surgery; this represents an increase from 32% in a similar study done approximately 10 years ago.

Conclusion

There is a growing trend for routine facial nerve monitoring in the setting of chronic ear surgery.

Recurrent Pleomorphic Adenoma of the Parotid Gland

Objective

To determine the benefit to postoperative facial function of intraoperative facial nerve monitoring (IFNM) during recurrent pleomorphic adenoma (RPA) parotid surgery.

Study Design

Cohort study with planned data collection.

Setting

Chinese PLA General Hospital.

Subjects and Methods

Fifty-eight RPA parotidectomies were performed between 2004 and 2012. Recurrence was confirmed by histopathologic examination. None of the patients had preoperative facial palsy. Electromyography-based IFNM was used in 28 patients; 30 patients were unmonitored. The durations of surgery and the severity of postoperative facial nerve palsy were compared between the 2 groups.

Results

There were no significant differences between the 2 groups in the incidence of immediate or permanent facial paralysis after RPA parotidectomy ( P = .95 and P = .36, respectively). However, the differences in the average duration of surgery and the severity of postoperative facial nerve palsy after total parotidectomy or wide resection were significant ( P < .01 and P = .01, respectively). In contrast, these differences were not significant after superficial parotidectomies ( P = .43 and P = .49, respectively). The average recovery time of temporary facial nerve paralysis was significantly shorter in the monitored group compared with the unmonitored group, independent of surgical technique ( P < .01).

Conclusion

The use of IFNM during total or wide resection RPA parotidectomy reduced the duration of surgery and the incidence of postoperative facial paralysis and enhanced recovery. However, there was little impact on facial nerve outcomes when IFNM was used during superficial RPA parotidectomy.

Prognostic factors for secondary recurrence of pleomorphic adenoma: a 20-year, retrospective study

Purpose:

To evaluate the results of treatment of parotid pleomorphic adenoma, and the risk factors for secondary recurrence.

Materials and methods:

Single-centre, retrospective study of 32 patients with pleomorphic adenoma recurrence managed between 1988 and 2008.

Results:

The mean age at diagnosis of primary pleomorphic adenoma recurrence was 43.4 years. Twenty-eight per cent of patients had secondary recurrence; 32 per cent had undergone two or more surgical resections and external adjuvant radiotherapy. An age of less than 25 years was significantly associated with an earlier primary recurrence (p = 0.008). The most significant histopathological risk factor for secondary recurrence was the presence of a multifocal tumour (p = 0.019). Other histopathological criteria (i.e. cellularity and capsule rupture) were not significant. Radiotherapy was not associated with a decrease in recurrence. Nine per cent of patients progressed to malignancy. The main surgical complication was definitive facial palsy (14 per cent).

Conclusion:

Pleomorphic adenoma recurrence requires surgery, with greatly increased risk to the facial nerve. Resection with clear surgical margins is required, especially in young patients with multifocal tumours. Radiotherapy may delay second recurrence in cases of multifocal tumour.

Salivary Gland Surgery and Medical Malpractice

Objective

To better understand the causes and outcomes of lawsuits involving salivary gland surgery by analyzing malpractice litigation trends to prevent future litigation and improve physician education.

Study Design

Analysis of a national database.

Setting

All US civil trials.

Subjects and Methods

The WESTLAW database was reviewed from January 1987 to March 2011. Data were compiled on the demographics of the defendant, anatomic site of injury, initial pathology, nature of injury, legal allegations, verdicts, and indemnities.

Results

Twenty-six cases met inclusion criteria and were selected for review. Verdicts/settlements for the plaintiffs predominated (58%), and the average sum of the plaintiff’s monetary award was $933,235. Sixteen cases (62%) involved injury to the parotid gland/duct, with 10 cases involving injury to the facial nerve. No cases were filed on the grounds of failure to use facial nerve monitoring. Nine cases (35%) involved injury to the submandibular gland/duct. The most common legal allegations listed were improper performance followed by unnecessary procedures. If failure or inadequate consent was a component of the legal allegations, the verdict outcome significantly favored the defendants.

Conclusion

Our study reveals that the plaintiffs in litigations involving salivary gland surgery have a slight advantage in outcomes with a fairly substantial award. Our litigation review reiterates the importance of detailed anatomic knowledge of the lingual and facial nerve to avoid the pitfalls of surgical error and consequent litigation. In addition, thorough preoperative evaluation of salivary gland pathology, including radiographic studies and needle biopsy, may help avoid errors in diagnosis and subsequent litigations.

Differences in sensitivity to rocuronium among orbicularis oris muscles innervated by normal or damaged facial nerves and gastrocnemius muscle innervated by somatic nerve in rats: combined morphological and functional analyses

OBJECTIVES/HYPOTHESIS

To evaluate mechanisms of discrepant responses to the nondepolarizing muscle relaxant rocuronium among normal and injured facial nerve-innervated orbicularis oris and tibial nerve-innervated gastrocnemius, and to provide information for the proper use of muscle relaxants to balance evoked electromyography (EEMG) monitoring and immobility in general anesthesia.

STUDY DESIGN

Randomized controlled study.

METHODS

Right-sided facial nerve injury was induced by crush axotomy in 18 Sprague-Dawley rats. At different rocuronium concentrations, muscular tension amplitude (MTA) was determined in vitro for normal and injured facial nerve-innervated orbicularis oris and gastrocnemius; the number of unsaturated acetylcholine receptors (AChRs) at end plates was determined by (125) I-α-bungarotoxin staining followed with gamma spectroscopy. The morphological composition of muscle fibers was determined by histological examination.

RESULTS

Following rocuronium incubation, the percentage of MTA inhibition (MTAI%) of gastrocnemius was significantly higher than the corresponding values of orbicularis oris (P < .05), and the degree of saturation of AChR in gastrocnemius was significantly greater than that in orbicularis oris (P < .05). The baseline MTA and AChR density of injured-side orbicularis oris was significantly smaller than those of the normal side, whereas no significant difference was found regarding MTAI% and the degree of AChR saturation between the normal and injured side.

CONCLUSIONS

The affinity of AChR at end plates and different number of AChR per unit fiber cross-sectional area may be the mechanisms for differential sensitivities to neuromuscular blockers between facial nerve-innervated muscles and somatic nerve-innervated muscles. The lower EEMG responses in the impaired facial nerve-innervated muscles may result from the lower AChR density at end plates compared with the normal facial nerve-innervated muscles.

[Intraoperative facial nerve monitoring for parotid gland surgery]

INTRODUCTION

The route of the facial nerve in its extracranial part determines the technique of parotid gland surgery. Permanent facial nerve paralysis after parotidectomy is not rare. It is the most devastating complication for the patient and surgeon. Facial nerve monitoring by observing or palpating the face during the surgery is a long-standing practice. Using an EMG device is a standard procedure at present.

AIM OF THE STUDY

Evaluation of the effectiveness of intraoperative facial nerve monitoring for parotid gland surgery.

MATERIAL AND METHODS

Fifty three patients operated on due to parotid gland tumour in the Head and Neck Surgery and Laryngological Oncology Department of the Greater Poland Cancer Center in 2007-2008. All patients had been provided with EMG and ENG examinations of the facial nerve before the surgery and continuous facial nerve monitoring during the operation. Facial nerve function after surgery was assessed according to the House-Brackmann grading system.

RESULTS

Six (12%) patients presented facial nerve dysfunction after surgery. Three (6%) patients had temporary paralysis grade III H-B with complete recovery in 6 weeks. Three (6%) patients with deep lobe tumour had grade V H-B with complete recovery in one patient after 3 months, and two (4%) patients had grade III H-B after one year since the surgery.

CONCLUSIONS

Intraoperative facial nerve monitoring should be a standard procedure during parotid gland surgery in most clinical situations.

Electrophysiologic facial nerve monitoring during parotidectomy

Facial nerve monitoring is an adjunctive method available to a surgeon during parotid surgery to assist with the functional preservation of the facial nerve. This review describes the goals, applications, technique, and benefits of electrophysiologic facial nerve monitoring during parotid surgery. A review and analysis of the relevant medical literature related to electrophysiologic facial nerve monitoring during parotid surgery are included.

[Management of the surgical pathology of the parotid gland: A review of 54 cases]

INTRODUCTION AND AIM OF THE STUDY

The management of the surgical pathology of the parotid gland and its results are relatively uniform. However, both in the diagnostic and the therapeutic aspects, there are some controversial issues which we discuss from the point of view of recent experience at our department.

METHODS

A descriptive and retrospective study was conducted on patients who underwent parotidectomy for any indication between July 2004 and June 2009 (5 years).

RESULTS

Fifty four parotidectomies were performed in 52 patients. CT was the most commonly used preoperative diagnostic imaging study. The accuracy of FNAB was 93.3%. 76% were benign processes; among them 7.3% with inflammatory causes. All of the surgical procedures from April 2005 onwards were performed with electrophysiological monitoring of the facial nerve. Superficial parotidectomy was performed in 75.6% of benign cases. The incidence of transient facial paresis in benign pathologies was of 14.6% (all of them of grades II and III). Two cases (both with total parotidectomy) had permanent facial mobility sequelae. The rhytidectomy incision was used preferentially in young women.

CONCLUSIONS

The controversial issues identified, due either to discrepancies or lack of enough evidence, were: the diagnostic role of MRI, the validity and usefulness of FNAB, the indications of surgical treatment, the need for facial nerve monitoring and the consideration of cosmetic aspects, in particular the indications of rhytidectomy incision.

The precision of four commonly used surgical landmarks for locating the facial nerve in anterograde parotidectomy in humans

In addition to using intra-operative facial nerve monitoring in helping to locate the position of the facial nerve in anterograde parotidectomy, numerous soft tissue and bony landmarks have been proposed to assist the surgeon in the early identification of this nerve. There is still dispute within the literature as to the most effective method, if any, of locating the nerve. The purpose of this study was to measure the distance (in twenty-six embalmed cadavers) from four of the most commonly used surgical landmarks to the main trunk of the facial nerve-the posterior belly of digastric muscle (PBDM), the tragal pointer (TP), the junction between the bony and cartilaginous ear canal (EAM) and the tympanomastoid suture (TMS). The main trunk of the facial nerve was found 5.5+/-2.1mm from the PBDM, 6.9+/-1.8 mm from the TP, 10.9+/-1.7 mm from the EAM and 2.5+/-0.4 mm from the TMS. From this, the TMS can be used as a reliable indicator for locating the main trunk of the facial nerve. In addition, this study also demonstrated a statistically significant difference between the sexes in relation to the two bony landmarks used here, the EAM and the TMS, with the facial nerve found further away from those landmarks in females compared to males. With the advent of 3D construction and reformatting of images, these values may come to the forefront in pre-operative planning for locating the facial nerve in anterograde parotidectomy.

Facial nerve mapping and monitoring in lymphatic malformation surgery

OBJECTIVE

Establish the efficacy of preoperative facial nerve mapping and continuous intraoperative EMG monitoring in protecting the facial nerve during resection of cervicofacial lymphatic malformations.

METHODS

Retrospective study in which patients were clinically followed for at least 6 months postoperatively, and long-term outcome was evaluated. Patient demographics, lesion characteristics (i.e., size, stage, location) were recorded. Operative notes revealed surgical techniques, findings, and complications. Preoperative, short-/long-term postoperative facial nerve function was standardized using the House-Brackmann Classification. Mapping was done prior to incision by percutaneously stimulating the facial nerve and its branches and recording the motor responses. Intraoperative monitoring and mapping were accomplished using a four-channel, free-running EMG. Neurophysiologists continuously monitored EMG responses and blindly analyzed intraoperative findings and final EMG interpretations for abnormalities.

RESULTS

Seven patients collectively underwent 8 lymphatic malformation surgeries. Median age was 30 months (2-105 months). Lymphatic malformation diagnosis was recorded in 6/8 surgeries. Facial nerve function was House-Brackmann grade I in 8/8 cases preoperatively. Facial nerve was abnormally elongated in 1/8 cases. EMG monitoring recorded abnormal activity in 4/8 cases--two suggesting facial nerve irritation, and two with possible facial nerve damage. Transient or long-term facial nerve paresis occurred in 1/8 cases (House-Brackmann grade II).

CONCLUSIONS

Preoperative facial nerve mapping combined with continuous intraoperative EMG and mapping is a successful method of identifying the facial nerve course and protecting it from injury during resection of cervicofacial lymphatic malformations involving the facial nerve.

Analysis of complications following surgical treatment of benign parotid disease

BACKGROUND

The objective of the study was to study the incidence of, and risk factors for developing complications following parotidectomy for benign disease, to improve preoperative patient counselling and better inform future surgical management.

METHODS

An 11-year retrospective review of 162 parotidectomies for benign disease, collecting and analysing data about presentation, investigations, surgical treatment, postoperative facial nerve function, Frey's syndrome and other surgical complications.

RESULTS

The mean age at presentation was 58 years. The commonest pathology was benign pleomorphic adenoma (43%), followed by Warthin's tumour (30%) and chronic sialadenitis (22%). Sialadenitis was a significant risk factor for facial nerve palsy and increased the incidence of salivary fistulas. Parotid duct ligation increased the risk of nerve palsy in the distribution of zygomatic and buccal branches. Operations for Warthin's tumour were associated with an increased risk of dysfunction of the cervical branch of the nerve. Half the patients had intraoperative facial nerve stimulation and this did not influence the likelihood of facial paresis. The recovery of facial nerve function showed a biphasic distribution, with 90% of patients having normal function within 12 months, followed by a slower recovery rate for up to 2 years.

CONCLUSION

The incidence of postoperative complications was influenced by the pathology, with inflammatory lesions significantly increasing the risk of facial nerve dysfunction and other complications, but also by variations in surgical practice, such as parotid duct ligation. Overall, the incidence of permanent facial paralysis was less than 2%, but temporary nerve palsy was common at 40%, with most patients regaining normal function within 1 year of the operation.

Continuous intraoperative facial nerve monitoring in predicting postoperative injury during parotidectomy

OBJECTIVES/HYPOTHESIS

To assess whether the use of continuous intraoperative facial nerve monitoring correlates to postoperative facial nerve injury during parotidectomy.

STUDY DESIGN

A retrospective analysis.

METHODS

Forty-five consecutive parotidectomies were performed using an electromyograph (EMG)-based intraoperative facial nerve monitor. Of those, 37 had complete data for analysis. Intraoperative findings and final interpretation of the EMGs were analyzed by a senior neurologist and neurophysiologist. All patients were analyzed, including those with preoperative weakness and facial nerve sacrifice.

RESULTS

The overall incidence of facial paralysis (House-Brackmann scale > 1) was 43% for temporary and 22% for permanent deficits. This includes an 11% incidence of preoperative weakness and 14% with intraoperative sacrifice. An abnormal EMG occurred in only 16% of cases and was not significantly associated with permanent or temporary facial nerve paralysis (chi, P < 1.0; Fisher's exact P < .68). Of the eight patients with permanent paralysis, only two had abnormalities on the facial nerve monitor. Also, only one of five patients with intraoperative sacrifice of the facial nerve had an abnormal EMG. Factors significantly associated with the incidence of facial paralysis include malignancy, advanced age, extent of parotidectomy, and dissection beyond the parotid gland (chi and Fisher's, P < .05).

CONCLUSIONS

The results suggest that abnormalities on the intraoperative continuous facial nerve monitor during parotidectomy do not predict facial nerve injury. The incidence of permanent and temporary facial nerve paralysis compare favorably with the literature given that this study includes patients with revision surgery, intraoperative sacrifice, and preoperative paralysis. Standard of care implications will be discussed.