Continuous Facial Nerve Monitoring during Pleomorphic Adenoma Recurrence Surgery

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.

Treatment of relapses of benign latero-cervical pathology: a narrative literature review

Benign laterocervical pathologies are not without pitfalls. Many may relapse after many years and, sometimes, they cannot be predicted. The purpose of this review is to describe the surgical measures necessary for the treatment of relapses of the most common benign laterocervical masses. We searched PubMed, Embase and Cochrane Central Register of Controlled Trials databases for articles describing the treatment of the most common benign cervical disease recurrences, and summarised available evidence in this narrative review. We overviewed observations about recurrent benign mixed tumour (pleomorphic adenoma), parapharyngeal space tumours and carotid body paragangliomas, thyroglossal duct anomalies and branchial cleft anomalies. Proper surgical technique is crucial for safely and effectively managing the relapses of benign latero-cervical diseases. Radiotherapy is indicated in several cases of recurrence such as pleomorphic adenoma and unresectable paraganglioma. Long-term follow-up is of utmost importance to promptly recognise and treat recurrencies.

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.

Microscopic Parotidectomy: A Prospective Study

To assess the parameters' setting of the microscope during parotidectomy and the impact of microscopic parotidectomy on facial nerve functional status. A prospective study was conducted on 28 patients in a tertiary care center, who underwent microscopic parotidectomy. Microscope's settings' like magnification, focal length, diameter of the visualized field, and clock position were recorded. Facial nerve functional status was also recorded. All surgeries were performed by right-handed surgeons using Leica F 20 M525 microscope. Clock position of microscope for right parotidectomy ranged between 7 and 10 o clock and for left, it ranged between 7 and 12 o clock. Magnification ranged between 1.3 × and 3.2 ×; magnifications of 1.3 × and 1.8 × were preferred from incision to separation of parotid from sternocleidomastoid muscle, 1.8 × and 2 × for dissection of the facial nerve trunk, and 2 × and 3.2 × for individual branches of the facial nerve. Focal length ranged between 251 and 410 mm and the diameter of the visualized field ranged between 7 and 14.7 cm. Out of 24 cases of benign lesions, 2 (8.3%) developed facial paresis which resolved in 3 months. Two out of four cases of malignancy developed permanent palsy as nerve branches were sacrificed to achieve tumor clearance. Using a microscope for parotidectomy is advantageous for facial nerve dissection, reducing chances of facial paralysis. The microscope was also found to be useful for teaching. The use of appropriate microscopic parameters avoids the glitch of transition from open to microscopic approach.

Patient safety and quality improvements in parotid surgery

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

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

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

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

Outpatient parotidectomy is safe and feasible for appropriately selected patients.

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.

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.

Three-dimensional double-echo steady-state with water excitation magnetic resonance imaging to localize the intraparotid facial nerve in patients with deep-seated parotid tumors

PURPOSE

To assess the utility of three-dimensional double-echo steady-state with water excitation (3D-DESS-WE) imaging for localizing deep-seated parotid tumors in relation to the facial nerve.

METHODS

A prospective study comparing the surgical outcomes of parotidectomy with or without 3D-DESS-WE sequence is currently enrolling the patients. Magnetic resonance imaging data from the first 25 patients with 3D-DESS-WE sequence were reviewed. Visibility of the intraparotid facial nerve was independently assessed by two neuroradiologists. The diagnostic performance of the 3D-DESS-WE sequence for prediction of deep lobe involvement was compared with that of two conventional methods based on the retromandibular vein line (RMVL) and facial nerve line (FNL). The relationship between the tumor and the main trunk of the facial nerve was also evaluated on the 3D-DESS-WE sequence.

RESULTS

On 3D-DESS-WE images, the main trunk, temporofacial division, and cervicofacial division of the intraparotid facial nerve were visualized in 100% (25/25), 48% (12/25), and 36% (9/25) of patients, respectively. The diagnostic accuracy of the 3D-DESS-WE sequence for prediction of deep lobe involvement was 92% (23/25), which was significantly superior to that of the RMVL (68% [17/25]; p = 0.008) and FNL (64% [16/25]; p = 0.004) methods. The relationship between the tumor and the main trunk of the facial nerve was correctly predicted in 92% (23/25) of 3D-DESS-WE images.

CONCLUSION

By direct visualization of the facial nerve, the 3D-DESS-WE sequence improved the preoperative localization of the intraparotid facial nerve in deep-seated parotid tumors. This information may help better surgical planning for deep-seated parotid tumors.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

Retrospective review of medical records.

SETTINGS

Two tertiary care centers.

PATIENTS AND METHODS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

LIMITATIONS

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

CONFLICT OF INTEREST

None.

Guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL), part II: Management of recurrent pleomorphic adenoma of the parotid gland

INTRODUCTION

The authors present the guidelines of the French Society of Otorhinolaryngology-Head and Neck Surgery (SFORL) for the management of recurrent pleomorphic adenoma (RPA) of the parotid gland.

METHOD

A review of the literature was performed by a multidisciplinary task force. Guidelines were drafted, based on the articles retrieved and the work group members' individual experience. There were then read and re-edited by an independent reading group. The proposed recommendations were graded A, B or C on decreasing levels of evidence.

RESULTS

Complete resection under neuromonitoring is recommended in case of RPA. The risks of progression and malignant transformation, which are higher the younger the patient, have to be taken into consideration. The risk of functional sequelae must be explained to the patient. MRI is recommended ahead of any surgery for parotid RPA, to determine extension and detect subclinical lesions. Radiotherapy should be considered in case of multi-recurrent pleomorphic adenoma after macroscopically complete revision surgery at high risk of new recurrence (microscopic residual disease), in case of RPA after incomplete resection, and in non-operable RPA.

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.

Natural history of recurrent pleomorphic adenoma: implications on management

BACKGROUND

Treating recurrent pleomorphic adenoma (RPA) aims to reduce risk of malignant transformation (MT) while avoiding facial nerve injury. Our objective was to systematically investigate this natural history of RPA and address the current rational for its treatment.

METHODS

The follow-up data of two nationwide series of PA was pooled with a focus on risk of MT and analyzed against the literature.

RESULTS

The combined nationwide data (n = 9003 PA patients) showed 3.1% with first recurrence of which 6.2% were malignant. In the literature first RPA rate was >7% at 20 years follow-up. MT occurred in 0% to 7%, and facial nerve damage increased from with each surgery 3% to 16% at first RPA to 18% to 30% at second RPA.

CONCLUSIONS

RPA showed a characteristic course with surgery being unreliable and damage to the facial nerve. The risk of MT was low. This might give flexibility towards a more conservative approach of management.

Surgical Anatomy of the Marginal Mandibular Nerve: A Systematic Review and Meta-Analysis

The high number of marginal mandibular nerve (MMN) anatomical variants have a well-known clinical significance due to the risk of nerve injury in several surgical procedures. The aim of this study was to find and systematize the available anatomical data concerning this nerve. The PubMed and Scopus databases were investigated in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. All studies reporting extractable data on the origin, course, splitting, anastomosis and relationship of the MMN with the mandible or the facial vessels were included. We included 28 studies analyzing 1861 halves. The MMN had one (PP = 35% 95% CI:18-54%), two (PP =35% 95% CI:18-54%), three (PP = 18% 95% CI:0-35%), or four branches (PP = 2% 95% CI:0-8%). Anastomosis with the great auricular nerve, transverse cervical nerve, mental nerve, and other branches of the facial nerve were defined. The origin of the MMN in relation to the parotid and the mandible was variable. The MMN nearly always crossed the anterior facial vein laterally (PP = 38% 95% CI:9-72% if single, PP = 57% 95% CI:22-90% when multiple); its relation with other vessels was less constant. At least one branch of the MMN was found below the inferior border of the mandible (IBM), with a PP of 39% (95% CI:30-50%). The MMN has high anatomical variability and it is more often represented by one or two branches; its origin is frequently described at the parotid apex and above the IBM, although in its course at least one branch often runs below the IBM. Its most frequent anastomosis is with the buccal branch of the facial nerve. Clin. Anat., 33:739-750, 2020. © 2019 Wiley Periodicals, Inc.

Recurrent benign pleomorphic adenoma of the parotid gland: Facial nerve identification and risk factors for facial nerve paralysis at re-operation

OBJECTIVE

Surgery for recurrent pleomorphic adenoma of the parotid gland is challenging since there is a considerable risk of facial nerve injury and a high re-recurrence rate. We investigated surgery for recurrent pleomorphic adenoma, focusing on management of the facial nerve.

METHODS

We reviewed 29 patients who underwent surgery for recurrent benign pleomorphic adenoma of the parotid gland at our department between 1999 and 2018. We examined clinicopathologic features and risk factors for facial nerve injury during reoperation.

RESULTS

Factors associated with difficulty in identifying the main trunk of the facial nerve during surgery were bilobar tumors, multiple tumors, and use of an S-shaped skin incision at the previous operation. When the facial nerve was identified intraoperatively, it could be preserved in 2/3 of patients, while the nerve was only preserved in 1/3 of patients when it was not identified. Factors related to permanent postoperative paralysis included recurrence in the deep lobe or both lobes and multiple tumors.

CONCLUSION

The probability of successfully preserving the facial nerve is relatively high if the nerve can be identified during surgery for recurrent pleomorphic adenoma, although intentional resection is necessary in some patients. Factors associated with difficulty in identifying the facial nerve are similar to those related to permanent postoperative paralysis, including bilobar tumors and multiple tumors. In patients with recurrent pleomorphic adenoma, preservation of the facial nerve is difficult, when they may have undergone previous extensive resection or have multiple tumors requiring subtotal or more extensive resection.

Intraoperative monitoring of marginal mandibular nerve during neck dissection

BACKGROUND

The purpose of this study was to assess the efficacy of intraoperative nerve integrity monitoring (NIM) to prevent marginal mandibular nerve injuries during neck dissection.

METHODS

This prospective study compared 36 patients undergoing NIM-assisted neck dissection from July 2014 to March 2015 to a cohort of 35 patients subjected to neck dissection over an identical period of time before the technique was introduced. We also assessed possible correlations between marginal mandibular nerve injuries and other factors, such as anthropometric measurements, presence of clinical neck metastases, type of neck dissection, and site of primary tumor.

RESULTS

The incidence of marginal mandibular nerve paralyses was significantly lower among the group of patients undergoing NIM-assisted neck dissection (P = .021). There was no significant difference in the duration of the procedure, and the technique resulted in a limited increase of cost. No other factor seemed to influence the onset of marginal mandibular nerve palsy.

CONCLUSION

In our opinion, NIM is a valuable aid for preventing marginal mandibular nerve injuries during neck dissection.

Recurrent Parotid Pleomorphic Adenomas: Our Clinical Experience

Objective

The aim of our study was to present our findings in a series of patients who were treated for recurrent parotid pleomorphic adenoma with their clinical, surgical, and follow-up information and to discuss them in light of the recent literature.

Methods

Eleven patients who had revision surgery for recurrent pleomorphic adenoma at our institution were retrospectively analyzed for the clinical and radiological features of their lesions, surgery type, facial nerve management, and follow-up period.

Results

Seven patients were females and four were males with an average age of 45 years. All patients underwent previous surgeries at other institutions. Revision surgery was performed with superficial parotidectomy in six patients and total conservative parotidectomy with preservation of the facial nerve in five patients. Two patients had lesions involving the facial nerve branches necessitating sacrifice of involved branches. One patient was given adjuvant radiotherapy because of adjacent lymphatic vessel involvement with tumor cells. During the mean follow-up period of 9.1 years, there were no recurrences in any of the patients.

Conclusion

Management of patients with recurrent parotid pleomorphic adenomas must be carefully planned according to the size, location, and multicentricity of the tumor and involvement of the facial nerve. Surgery should aim at reaching tumor-free surgical margins. Sacrifice of the facial nerve should be considered only in cases with direct involvement. In the postoperative period, patients must be followed up regularly for early diagnosis of recurrences.

Preoperative percutaneous nerve mapping of the mandibular marginal branch of the facial nerve

OBJECTIVE

In this study, we introduce a reliable method for mapping the location of the mandibular marginal branch of the facial nerve. The utility of preoperative percutaneous mandibular marginal branch mapping and continuous intraoperative nerve monitoring during operation with a submandibular approach is reported.

MATERIALS AND METHODS

The mapping technique was performed in 40 patients. Electromyography surface electrodes were placed on the orbicularis oris muscles. A modified bipolar probe with an adjustable distance between the 2 tips was used to apply surface stimulation at a frequency of 1 Hz to 2 Hz. The stimulating current most frequently used was 5.0 mA to 5.5 mA. By moving the electrode at right angles across the suspected path of the nerve around the marginal border of the mandible, 4 to 5 points were marked and connected, where the orbicularis oris contracted and the action potential was evoked. After general anesthesia, the mapping path was verified using needle electrodes with different needle-to-nerve distances.

RESULTS

The nerve could be mapped preoperatively in all patients and were protected in 39 patients. The thresholds of the needle electrode on the mapping path were at or below 0.5 mA, verifying the accuracy of mapping.

CONCLUSIONS

Preoperative percutaneous nerve mapping was a precise method of identifying the location of the nerve and could protect the nerve from accidental injury.

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.

Etiology and management of recurrent parotid pleomorphic adenoma

The objective of this review study was to encompass the relevant literature and current best practice options for this challenging, sometimes incurable problem. The source of the data was Ovid MEDLINE from 1946 to 2014. Review methods consisted of articles with clinical correlates. The most important cause of recurrence is enucleation with rupture and incomplete tumor excision at operation. Incomplete pseudocapsule, extracapsular extension, pseudopods of pleomorphic adenoma tissue, and satellite pleomorphic beyond the pseudocapsule are also likely linked to recurrent pleomorphic adenoma. Most recurrent pleomorphic adenoma are multinodular. Magnetic resonance imaging is the imaging study of choice for recurrent pleomorphic adenoma. Nerve integrity monitoring may reduce morbidity for recurrent pleomorphic adenoma. Treatment of recurrent pleomorphic adenoma must be individualized. Total parotidectomy, given the multicentricity of recurrent pleomorphic adenoma, is appropriate in many patients, but may be inadequate to control recurrent pleomorphic. There is accumulating evidence from retrospective series that postoperative radiation therapy results in significantly better local control.

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.

Supramaximal stimulation during intraoperative facial nerve monitoring as a simple parameter to predict early functional outcome after parotidectomy

CONCLUSION

A supramaximal stimulation at 2 mA during intraoperative electromyographic (EMG) facial nerve monitoring appears to be a simple and effective parameter to predict immediate postoperative injury.

OBJECTIVES

To assess the role of systematic intraoperative facial nerve monitoring in predicting the early functional outcomes obtained after parotidectomy.

METHODS

Data were collected from patients who underwent parotidectomy. Intraoperative EMG monitoring of the facial nerve was performed by registering two parameters, event intensity (>100 μV) and amplitude of response after a supramaximal stimulation at 2 mA, at the beginning and end of gland removal. Early postoperative clinical functional facial nerve disorder was assessed at day 2.

RESULTS

Overall, 50 patients were included and an early facial dysfunction was detected in 27 cases (54%). The maximal response amplitude after supramaximal stimulation at the trunk of the facial nerve was higher in patients with normal facial function compared with those with poor outcomes at the end of surgery (p < 0.01). The postdissection to predissection ratios of maximal response amplitude, but not the stimulation thresholds, were indicative of a nerve conduction block and were significantly lower in the patient group with a poor outcome compared with the group with a normal facial outcome (p < 0.02).

Is surgical excision of lipomas arising from the parotid gland systematically required?

Lipomas arising from the parotid gland are very rare. We report a 10-year experience in a single institution (La Timone University Hospital of Marseille, France). Among 614 parotidectomies for neoplasms performed from 1998 to 2008, 12 lipomas were identified. A retrospective analysis based on medical records was made. Evaluation, analysis and current management of lipomas of the parotid gland are described. Lipomas accounted for 2% of all parotid neoplasms and 2.6% of benign tumors in our series. The median age of patients was 60 years with a M/F sex ratio of 5-1. The main presentation was a soft asymptomatic, slow-growing, mobile mass although 30% had an indurated mass on palpation. Diagnosis of lipoma, based on the results of imaging, was made preoperatively in all cases. The mean tumor duration prior to excision was 11.5 months. The surgical decision was made regarding increased swelling with functional/esthetic discomfort in 83% of cases. Partial parotidectomy was performed in most cases. Postoperative complications occurred in 16% of cases although no permanent complication was observed. No recurrence was observed in our series. Histologically, 92% of tumors were classic lipomas. Lipomas can be clinically misleading since 30% of patients in our series showed an indurated mass on palpation. Preoperative imaging, especially MRI, is the cornerstone of their management as it allows very accurate lipoma diagnosis. Since in our series, diagnosis of lipoma had been made preoperatively in all cases, the surgical excision could be delayed and finally surgical decision has been made for esthetic and/or functional considerations in more than 80% of cases.

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.

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.

Histopathologic and functional effects of facial nerve following electrical stimulation

The aim of the study is to investigate the functional and histopathologic changes in facial nerve due to the application of various violent and numerous electrical stimuli to the facial nerve. The study was carried out with Wistar rats weighing between 200 and 300 g. The facial nerves of the subjects were located and stimulated with electrical stimulator. Then five groups were created with 18 subjects in each group: Group 1, 1 milliampere (mA) electrical stimulus applied; Group 2, 2 mA electrical stimulus applied; Group 3, 3 mA electrical stimulus applied; Group 4, 4 mA electrical stimulus applied; Group 5, 5 mA electrical stimulus applied. All groups were divided into three sub-groups, each consisting of six subjects. The facial nerves of the subjects in first sub-group were stimulated 10 times, in second sub-group were stimulated 20 times and those in third sub-group were stimulated 30 times. The functions of the facial nerves were evaluated on first day, first week and first month, respectively. The facial nerves with branches were dissected from the surrounding tissues carefully. These specimens were investigated by light microscope about axonal degeneration, macrovacuolization and vascular congestion. Loss of facial functions was not observed in the subjects during follow-up process. There was no significant difference between groups regarding axonal degeneration, macrovacuolization and vascular congestion (P > 0.05). While less axonal degeneration was observed in group which was stimulated 10 times, more axonal degeneration was observed in groups which were stimulated 20 and 30 times (P < 0.05). The axonal degeneration, macrovacuolization and vascular congestion were observed more in 1-day groups (P < 0.05). Consequently, lesser violence and lesser number of electrical stimulus application to the facial nerve appears to be an important criterion for not damaging the facial nerve in patients in whom stimulators have been used.

[Tumoral pathology of salivary glands. Our experience]

INTRODUCTION AND OBJECTIVES

We report a descriptive epidemiologic study of 63 patients with major and minor salivary gland tumours diagnosed at our centre over the last ten years.

METHODS

The data collected from all patients included gender, age, location, histopathology, diagnostic procedures, treatment and follow-up.

RESULTS

Among the 38 males and 25 females, we found 39 with benign tumours and 24 with malignant tumours. Most of these tumours (42; 67%) arose in the parotid gland, 12 (19%) in the submaxillary gland, 7 (11%) in the palate and 2 (3%) in external auditory canal. The mean age was 54 years for benign tumours and 80 years for malignant ones. The most common benign tumours found were pleomorphic adenomas (67%) whereas epidermoid carcinoma (54%) followed by lymphomas (25%) were the most frequent among malignant tumours.

CONCLUSIONS

We have found two main differences with previously reported studies: the elevated mean age of patients with malignant tumours and, probably as a result of this advanced age, the high incidence of squamous cell carcinoma due to metastatic dissemination of skin cancers.

[Surgery treatment of salivary gland tumors]

INTRODUCTION

Tumors of parotid gland represent a diverse group of neoplasms with varied clinical behaviors.

MATERIAL AND METHODS

The diagnostic methods and treatment of salivary gland tumors are presented in this paper. The authors describe the group of 44 patients with salivary gland tumors treated surgically in ENT Departament Laryngology of Medical University in Łódź. Enucleation, partial and total parotidectomy were performed. Neurosign 100 unit was used during parotidectomy to monitoring course of facial nerve.

RESULTS

Tumor mixtus was a dominate type of tumors. Only three patients with malignant tumor had facial nerve paralysis after surgery.

CONCLUSIONS

(1) The extent of the surgical procedure depends on histopathologic diagnosis. (2) Using of facial nerve monitoring during parotid surgery improves its outcomes.

Optical stimulation of the facial nerve: a new monitoring technique?

OBJECTIVES/ HYPOTHESIS

One sequela of skull base surgery is iatrogenic damage to cranial nerves, which can be prevented if the nerve is identified. Devices that stimulate nerves with electric current assist in nerve identification. Contemporary devices have two main limitations: 1) the physical contact of the stimulating electrode and (2) the spread of the current through the tissue. In contrast to electrical stimulation, pulsed infrared optical radiation can be used to safely and selectively stimulate neural tissue and might be valuable for screening.

METHODS

The gerbil facial nerve was exposed to 250 microsecond pulses of 2.12 microm radiation delivered via a 600-microm-diameter optical fiber at a repetition rate of 2 Hz. With use of 27 GA, 12-mm intradermal electrodes, muscle action potentials were recorded. Nerve samples were examined for possible tissue damage.

RESULTS

Eight facial nerves were stimulated with radiant exposures between 0.71 and 1.77 J/cm, resulting in compound muscle action potentials (CmAPs) that were simultaneously measured at the m. orbicularis oculi, m. levator nasolabialis, and m. orbicularis oris. Resulting CmAP amplitudes were 0.3 to 0.4 mV, 0.15 to 1.4 mV, and 0.3 to 2.3 mV, respectively, depending on the radial location of the optical fiber and the radiant exposure. Individual nerve branches were also stimulated, resulting in CmAP amplitudes between 0.2 and 1.6 mV. Histology revealed tissue damage at radiant exposures of 2.2 J/cm but no apparent damage at radiant exposures of 2.0 J/cm.

CONCLUSIONS

The experiments showed that selective muscle action potentials can be evoked optically in the gerbil facial nerve without direct physical contact.

Contemporary management of tumors of the salivary glands

Management of tumors of the salivary glands requires a detailed understanding of the anatomy and pathologic processes affecting these glands. Salivary glands give rise to benign and malignant neoplasms and are affected by a variety of systemic diseases. CT remains the most common primary imaging study; magnetic resonance imaging and ultrasound have also been explored. Fine-needle aspiration as part of the diagnostic evaluation remains controversial due to varying sensitivities and specificities. Surgical extirpation is the primary modality for management of tumors of the salivary glands. Parotid surgery carries a potentially high morbidity with possible unsightly scarring and facial nerve damage. Nontraditional surgical approaches and instrumentation, as well as facial nerve monitoring, can decrease the morbidity of a parotidectomy. In specific instances, malignant salivary gland tumors warrant cervical lymphadenectomy. Adjuvant therapy is primarily accomplished with radiation. Chemotherapy continues to play a palliative role in salivary gland malignancies; however, newer trials are investigating the therapeutic role of chemotherapy.

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.

Parotidectomy for benign parotid disease at a university teaching hospital: outcome of 963 operations

OBJECTIVE/HYPOTHESIS

The objective of this study was to analyze the perioperative and long-term complications after standardized lateral and total parotidectomy for benign parotid tumors and chronic parotitis with special regard on the training skill of the surgeons at a university teaching center. All teaching operations were performed under strict microscopic control and supervision of experienced surgeons.

STUDY DESIGN

The authors conducted a retrospective unicentric study in a tertiary university center.

METHODS

Medical records of 963 lateral and total parotidectomies treated from 1986 to 2004 were analyzed with regard to perioperative and long-term complications. The surgeons' expertise to perform a parotidectomy was classified as beginner (0-20 parotidectomies performed), advanced (21-50), experienced (51-100), or highly experienced (>100).

RESULTS

Eighty-five percent of the cases were primary operations (85%) and 15% revision operations. A lateral parotidectomy was necessary in 61% and total parotidectomy in 39%. The mean operation time was 192 minutes. The incidence of transient facial nerve dysfunction was 25%, and 6% for permanent weakness, respectively. Treatment for Frey's syndrome was performed in 5%. First recurrence for pleomorphic adenoma was observed in 2% and for Warthin's tumor in 3%. Significantly more complications were seen after total parotidectomy and in revision cases. Beginners and advanced surgeons (operated 41% of the cases) needed a longer operation time than experienced and highly experienced surgeon (59% of the cases). The surgeon's expertise had no influence on the incidence of complications.

CONCLUSIONS

Standardized education in lateral and total parotidectomy for treatment of benign parotid disease under precise microscopic control is safe, demonstrates good results, and has low perioperative and long-term morbidity.