Predictive value of facial motor-evoked potential and electromyography for facial motor function in vestibular schwannoma surgery.

PURPOSE: Intraoperative neuromonitoring (IONM) aims to preserve facial nerve (FN) function during vestibular schwannoma (VS) surgery. However, current techniques such as facial nerve motor evoked potentials (FNMEP) or electromyography (fEMG) alone are limited in predicting postoperative facial palsy (FP). The objective of this study was to analyze a compound fEMG/FNMEP approach. METHODS: Intraoperative FNMEP amplitude and the occurrence of fEMG-based A-trains were prospectively determined for the orbicularis oris (ORI) and oculi (OCU) muscle in 322 VS patients. Sensitivity and specificity of techniques to predict postoperative FN function were calculated. Confounding factors as tumor size, volume of intracranial air, or IONM duration were analyzed. RESULTS: A relevant immediate postoperative FP was captured in 105/322 patients with a significant higher risk in large VS. While fEMG demonstrated a high sensitivity (77% and 86% immediately and 15 month postoperative, respectively) for identifying relevant FP, specificity was low. In contrast, FNMEP have a significantly higher specificity of 80.8% for predicting postoperative FP, whereas the sensitivity is low. A retrospective combination of techniques demonstrated still an incorrect prediction of FP in ~ 1/3 of patients. CONCLUSIONS: FNMEP and fEMG differ in sensitivity and specificity to predict postoperative FP. Although a combination of IONM techniques during VS surgery may improve prediction of FN function, current techniques are still inaccurate. Further development is necessary to improve IONM approaches for FP prediction.

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

PURPOSE: Facial palsy (FP) is the most significant complication of parotidectomy. Currently, the use of intermittent intraoperative neuromonitoring (iIONM) in parotid surgery facilitates nerve detection, which is paramount to nerve protection. Continuous IONM (cIONM), as applied in thyroid surgery, enables real-time information on electrophysiological nerve status through continuous nerve stimulation, thereby allowing consequent amplitude analysis. To date, the application of cIONM in parotid surgery has not been noted in literature. METHODS: We performed parotidectomies with anterograde facial nerve visualization using cIONM in 32 consecutive patients in a prospective study (German Register of clinical studies-DRKS 00011051) during the period October 2016 to January 2020. After the facial trunk had been exposed, an atraumatic stimulation electrode was placed and the nerve was stimulated at 3 Hz, at a low threshold (0.62 ± 0.06 mA), for the entire duration of the preparation. Selected electrophysiological parameters were collected and compared to postoperative facial nerve function, measured by the House-Brackmann grading system. RESULTS: In the post hoc analysis, a significant correlation between a drop in amplitude (< 50% of the "baseline" amplitude) and postoperative FP was recorded (p = 0.001). True positive prediction of FP was noted in 14 out of 16 patients and true negative in 10 out of 16. The sensitivity was 87.5% (AUC 0.75), with a high negative predictive value of 83.3%. CONCLUSION: cIONM has significant value in predicting postoperative FP in parotidectomy. Future development of an acoustic/optic warning system in IONM devices could prevent nerve injury in real time.

Evaluation of the effectiveness of superficial parotidectomy and partial superficial parotidectomy for benign parotid tumours: a meta-analysis.

OBJECTIVE: To quantify the results of superficial parotidectomy (SP) and partial SP (PSP) for benign parotid tumours using a systematic evaluation method. METHODS: A systematic search of English and Chinese databases (PubMed, Web of Science, Cochrane Library, China Knowledge Network, Wanfang and Vipshop) was conducted to include studies comparing the treatment outcomes of SP with PSP. RESULTS: Twenty-three qualified, high-quality studies involving 2844 patients were included in this study. The results of this study showed that compared to the SP surgical approach, the PSP surgical approach reduced the occurrence of temporary facial palsy (OR = 0.33; 95% confidence interval [CI] 0.26-0.41), permanent facial palsy (OR = 0.28; 95% CI 0.16-0.52) and Frey syndrome (OR = 0.36; 95% CI 0.23-0.56) in patients after surgery, and the surgery operative time was reduced by approximately 27.35 min (95% CI - 39.66, - 15.04). However, the effects of PSP versus SP on salivary fistula (OR = 0.70; 95% CI 0.40-1.24), sialocele (OR = 1.48; 95% CI 0.78-2.83), haematoma (OR = 0.34; 95% CI 0.11-1.01) and tumour recurrence rate (OR = 1.41; 95% CI 0.48-4.20) were not statistically significant. CONCLUSION: Compared with SP, PSP has a lower postoperative complication rate and significantly shorter operative time, suggesting that it could be used as an alternative to SP in the treatment of benign parotid tumours with the right indications.

[Preservation, reconstruction, and rehabilitation of the facial nerve]. / Erhalt, Rekonstruktion und Rehabilitation des N. facialis.

Handling of the facial nerve during surgery for parotid cancer is relevant for the patient's long-term quality of life. In about two thirds of cases, the facial nerve is not affected by the tumor. In these cases, in addition to complete tumor resection, identification and preservation of the facial nerve are important components of a successful operation. If the nerve is infiltrated by the tumor, the affected part must be resected during radical parotidectomy. When possible, primary nerve reconstruction leads to the best long-term cosmetic and functional outcomes. Individual selection of the optimal treatment concept is based on clinical examination of facial muscle mobility, preoperative imaging to understand the positional relationship between tumor and nerve, and on the basis of an electrophysiological examination of nerve function. Intraoperatively, standardized dissection helps to identify and preserve the facial nerve. If radical parotidectomy is indicated, in addition to one-step reconstruction, preoperative diagnostic tests can help to plan postoperative adjuvant therapy. The aim of rehabilitation is restoration of facial tone, facial symmetry, and movement of the paralyzed face. Restoration of eye closure is of high importance. The surgical treatment of facial paralysis has seen many improvements in recent years. The present work provides an overview of the most recent advances in diagnostics, surgical techniques, and further possibilities for preventing damage to the normal facial nerve during parotid cancer treatment. Furthermore, the options for rehabilitation of the tumor-infiltrated facial nerve in the context of treatment of salivary gland malignancies are described.

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.

[Complications in the surgery of the parotid salivary glands. Causes, mechanisms of development, methods of prevention]. / Oslozhneniya v khirurgii okoloushnykh slyunnykh zhelez. Prichiny, mekhanizmy razvitiya, sposoby profilaktiki.

Operations for neoplasms of the parotid salivary gland require from the surgeon a deep knowledge of the anatomical and topographic features of this area and technical skill, which puts it in a number of «jewelry¼ operations that require patience and concentration. The review is devoted to the topic of specific postoperative complications after parotidectomy or subtotal resection of the gland. These include relapses of tumors, paralysis or paresis of facial muscles, Frey syndrome, salivary fistulas or sialocele, violation of skin sensitivity, soft tissue deformity. The review presents the frequency and causes of complications, mechanisms of their development, methods of prevention and elimination.

A modified method for minimizing damage to the marginal mandibular branch (MMB) during partial superficial parotidectomy(PSP): A retrospective study.

The aim of this study was to compare modified partial superficial parotidectomy (MPSP) with conventional partial superficial parotidectomy (CPSP) in a retrograde approach, and to determine whether MPSP can reduce the risk of injury to the MMB of the facial nerve and the rate of postoperative facial palsy. Patients with benign parotid gland tumors of the superficial lobe were included retrospectively in two groups: one group was treated with CPSP; the other group was treated with MPSP, in which the MMB was dissected in an anterograde direction or not dissected. The patients' sex and age, location of tumor, size of tumor (maximum tumor diameter), histopathological distribution, operative time, and incidence of postoperative facial nerve weakness were compared. There was no significant difference in operative time between the two groups (p = 0.913). There was a significant difference (p = 0.008) in postoperative facial nerve weakness, with temporary facial nerve weakness observed in 19 and five patients in the CPSP and MPSP groups, respectively. Furthermore, there was a significant difference (p = 0.009) in MMB weakness, with temporary MMB weakness observed in 15 and three patients in the CPSP and MPSP groups, respectively. There was no significant difference (p = 0.564) in the weakness of other branches between the two groups. All cases of paresis scored ≤3 on the House-Brackmann scale, and all cases of temporary facial nerve weakness resolved within 6 months of surgery. No patient developed permanent paralysis. Within the limitations of the study, it seems that modified partial superficial parotidectomy (MPSP) should be preferred over conventional partial superficial parotidectomy (CPSP) whenever appropriate.

Superficial Parotidectomy: Impact of Postoperative Drainage.

BACKGROUND: Use of suction drain after superficial parotidectomy (SP) is based on national consensus considered best practice, but there is no evidence on the effect of the treatment. The aim of the present study is to evaluate the effectiveness of drainage after SP by evaluating the rate of complications after SP in relation to the (ie, duration) of drainage and tumor size. METHODS: Retrospective analysis was performed involving data from all consecutive patients undergoing SP at the Ear, Nose, and Throat department, Regional Hospital West Jutland, Denmark, between January 1, 2011, and December 31, 2017. Demographics including comorbidity, medication, tumor size, postoperative secretion through the drainage, as well as complications (hematoma, seroma, infection, fistulas, Frey syndrome, facial nerve palsy) were registered. Patients with secretion below 25 mL were compared to patients with secretion above 25 mL, that is, drainage less than 24 hours versus longer than 24 hours. Results: Two hundred five consecutive patients undergoing SP were enrolled. The overall risk of postoperative infection was 16.2%. Ten of 33 patients with infection were also diagnosed with an hematoma or seroma. The risk of infection increased with secretion above 25 mL (27.2%) compared to patients with less than 25 mL (13.1%; P = .0318). The same accounts for the risk of seromas/hematomas (P = .0055). We found no evidence that demographics or comorbidity correlated to the secretion in the drainage, but there is a tendency toward male gender having a higher risk off secretion above 25 mL (odds ratio 1.39). CONCLUSION: Overall, the risk of complications after SP increased with secretion beyond 25 mL (ie, drainage for more than 24 hours). This applied in particular to infections and seromas/hematomas demanding treatment. The use of routine drainage after SP is questionable, and a randomized trial is warranted to unravel the necessity of postoperative drainage.

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.

Facial Nerve EMG: Low-Tech Monitoring with a Stopwatch.

OBJECTIVE: The quantity of A-trains, a high-frequency pattern of free-running facial nerve electromyography, is correlated with the risk for postoperative high-grade facial nerve paresis. This correlation has been confirmed by automated analysis with dedicated algorithms and by visual offline analysis but not by audiovisual real-time analysis. METHODS: An investigator was presented with 29 complete data sets measured during actual surgeries in real time and without breaks in a random order. Data were presented either strictly via loudspeaker (audio) or simultaneously by loudspeaker and computer screen (audiovisual). Visible and/or audible A-train activity was then quantified by the investigator with the computerized equivalent of a stopwatch. The same data were also analyzed with quantification of A-trains by automated algorithms. RESULTS: Automated (auto) traintime (TT), known to be a small, yet highly representative fraction of overall A-train activity, ranged from 0.01 to 10.86 s (median: 0.58 s). In contrast, audio-TT ranged from 0 to 1,357.44 s (median: 29.69 s), and audiovisual-TT ranged from 0 to 786.57 s (median: 46.19 s). All three modalities were correlated to each other in a highly significant way. Likewise, all three modalities correlated significantly with the extent of postoperative facial paresis. As a rule of thumb, patients with visible/audible A-train activity < 1 minute presented with a more favorable clinical outcome than patients with > 1 minute of A-train activity. CONCLUSION: Detection and even quantification of A-trains is technically possible not only with intraoperative automated real-time calculation or postoperative visual offline analysis, but also with very basic monitoring equipment and real-time good quality audiovisual analysis. However, the investigator found audiovisual real-time-analysis to be very demanding; thus tools for automated quantification can be very helpful in this respect.

Controversies in the Workup and Surgical Management of Parotid Neoplasms.

OBJECTIVE: Parotid neoplasms are a rare heterogeneous group of tumors with varied clinical presentation and behavior. Here we provide an evidence-based review of the contemporary approach to evaluation and surgical management of parotid tumors. DATA SOURCE: PubMed and Web of Science Databases. REVIEW METHODS: Searches of the PubMed and Web of Science databases were performed on subjects related to the diagnosis and surgical management of parotid neoplasms. Particular emphasis was placed on the following areas: evaluation of parotid tumors, including imaging workup and the utility of fine-needle aspiration; extent of surgery of the primary lesion, including the extent of parotidectomy as well as oncologic management of the facial nerve; the extent of surgery of involved and at-risk cervical lymphatics; and parotid bed reconstruction. Articles published from 2014 to the present were prioritized, supplementing with information from prior studies in areas where data are lacking. CONCLUSION: A summary of the literature in these areas is outlined to provide an evidence-based approach to evaluation and management of parotid neoplasms. IMPLICATIONS FOR PRACTICE: While data are available to help guide many aspects of workup and management of parotid neoplasms, further research is needed to refine protocols for this heterogeneous group of diseases.

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.

Continuous dynamic mapping to avoid accidental injury of the facial nerve during surgery for large vestibular schwannomas.

In vestibular schwannoma (VS) surgery postoperative facial nerve (CN VII) palsy is reducing quality of life. Recently, we have introduced a surgical suction device for continuous dynamic mapping to provide feedback during tumor resection without switching to a separate stimulation probe. The objective was to evaluate the reliability of this method to avoid CN VII injury. Continuous mapping for CN VII was performed in large VS (08/2014 to 11/2017) additionally to standard neurophysiological techniques. A surgical suction-and-mapping probe was used for surgical dissection and continuous monopolar stimulation. Stimulation was performed with 0.05-2 mA intensities (0.3 msec pulse duration, 2.0 Hz). Postoperative CNVII outcome was assessed by the House-Brackmann-Score (HBS) after 1 week and 3 months following surgery. Twenty patients with Koos III (n = 2; 10%) and Koos IV (n = 18; 90%) VS were included. Preoperative HBS was 1 in 19 patients and 2 in 1 patient. Dynamic mapping reliably indicated the facial nerve when resection was close to 5-10 mm. One week after surgery, 7 patients presented with worsening in HBS. At 3 months, 4 patients' facial weakness had resolved and 3 patients (15%) had an impairment of CN VII (HBS 3 and 4). Of the 3 patients, near-total removal was attempted in 2. The continuous dynamic mapping method using an electrified surgical suction device might be a valuable additional tool in surgery of large VS. It provides real-time feedback indicating the presence of the facial nerve within 5-10 mm depending on stimulation intensity and may help in avoiding accidental injury to the nerve.

Impact of Motor-Evoked Potential Monitoring on Facial Nerve Outcomes after Vestibular Schwannoma Resection.

OBJECTIVES:: Assess the utility of intraoperative transcranial facial motor-evoked potential (FMEP) monitoring in predicting and improving facial function after vestibular schwannoma (VS) resection. STUDY DESIGN:: Retrospective chart review. METHODS:: Data were obtained from 82 consecutive VS resections meeting inclusion criteria. Sixty-two cases were performed without FMEP and 20 with FMEP. Degradation of FMEP response was defined as a final-to-baseline amplitude ratio of 0.5 or less. House-Brackmann (HB) grade was assessed preoperatively, postoperatively, at follow-up assessments, and it was compared between pre- and post-FMEP cohorts. Positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity of FMEP degradation in predicting facial weakness were calculated. RESULTS:: In the pre-FMEP group, at length of follow-up (LOF) ⩾9 months, 83.9% (52/62) of patients exhibited HB 1-2 outcome. In the post-FMEP cohort, 75.0% (15/20) exhibited HB 1-2 function at LOF ⩾9 months. There was no difference in rates of HB 1-2 outcomes between groups in the immediate postoperative period ( P = .35) or at long-term follow-up ( P = 1.0). With respect to predicting immediate postoperative facial function, FMEP demonstrated high specificity (88.9%) and moderate sensitivity (54.5%). The PPV and NPV for immediate postoperative facial function were 85.7% and 61.5%, respectively. With respect to long-term (⩾9 months LOF) facial function, intraoperative FMEP was moderately sensitive (71.4%) and highly specific (84.6%); PPV was moderate (71.4%), and NPV was high (84.6%). CONCLUSIONS:: Intraoperative FMEP is highly specific and moderately sensitive in predicting postoperative facial function for patients undergoing VS resection, but its use may not be associated with improved facial nerve outcomes. LEVEL OF EVIDENCE:: 4.

Strategy for facial nerve management during surgical removal of benign jugular foramen tumors: Outcomes and indications.

OBJECTIVE: Classical surgical management of jugular foramen (JF) tumors usually requires facial nerve rerouting which results in permanent facial palsy in most patients. The purpose of the article is to study the outcomes of different rerouting techniques, and to discuss their indications. MATERIAL AND METHODS: We retrospectively reviewed 98 patients with JF tumors operated at our center between January 2008 and December 2016 using different surgical approaches with the following procedures for facial nerve management: total anterior rerouting (TR), partial anterior rerouting (PR), and fallopian bridge (FB) technique. The data for facial nerve management, surgical outcome and postoperative facial nerve function were collected from the medical records. RESULTS: In the study, there were 48 males and 50 females. Of them, 61 (62.2%) were jugular paragangliomas, 22 (22.4%) schwannomas, and 15 (15.3%) meningiomas. Total tumor removal was achieved in 95 (96.9%) patients, while near-total removal was achieved in 3 (3.1%) paragangliomas. TR was applied in 31 (31.6%) patients with PR in 26 (26.5%) patients, and FB in 41 (41.8%) patients. The mean follow-up duration was 39.4±22.6 months, and 2 recurrences of paragangliomas were observed. Seventy-five patients (76.5%) had good facial function (HB I-II) at 1 year after surgery, the patients who received a TR approach presented significantly less HB I-II FN function (48.4%) than those with PR (82.6%, P<0.05) or those with FB technique (95.1%, P<0.001). 21 patients (21.4%) presented new-onset lower cranial nerve dysfunction of which 13 recovered at 1 year after surgery. CONCLUSION: Facial nerve management in JF tumors should be tailored individually. No-rerouting methods, such as the fallopian bridge technique, bring significantly better results in terms of facial nerve function, which might be performed first during surgery; its indication is based mainly on the tumor type and extent.

Electrical stimulation-based nerve location prediction for cranial nerve VII localization in acoustic neuroma surgery.

INTRODUCTION: Cranial nerve (CN) VII localization is a critical step during acoustic neuroma surgery because the nerve is generally hidden due to the tumor mass. The patient can suffer from Bell's palsy if the nerve is accidentally damaged during tumor removal. Surgeons localize CN VII by exploring the target area with a stimulus probe. Compound muscle action potentials (CMAPs) are elicited when the probe locates the nerve. However, false positives and false negatives are possible due to unpredictable tissue impedance in the operative area. Moreover, a single CMAP amplitude is not correlated with probe-to-nerve distance. OBJECTIVES: This paper presents a new modality for nerve localization. The probe-to-nerve distance is predicted by the proposed nerve location prediction model. METHODS: Input features are extracted from CMAP responses, tissue impedance, and stimulus current. The tissue impedance is calculated from the estimated resistance and capacitance of the tissue equivalent circuit. In this study, experiments were conducted in animals. A frog's sciatic nerve and gastrocnemius were used to represent CN VII and facial muscle in humans, respectively. Gelatin (2.8%) was used as a mock material to mimic an acoustic neuroma. The %NaCl applied to the mock material was used to emulate uncontrollable impedance of tissue in the operative area. RESULTS: The 10-fold cross-validation results revealed an average prediction accuracy of 86.71% and an average predicted error of 0.76 mm compared with the measurement data. CONCLUSION: The proposed nerve location prediction model could predict the probe-to-nerve distance across various impedances of the mock material.

[Current trends in surgery for benign parotid lesions]. / Gutartige Parotistumore: moderne Therapiekonzepte.

Parotidectomy is the standard procedure for treatment of benign parotid tumors. Nowadays, one of the main objectives of surgery is to minimize morbidity. However, the debate about the appropriate surgical technique in parotid surgery is still ongoing. There is a high level of evidence, that limited parotidectomy techniques are associated with fewer complications and especially with lower prevalence of permanent facial nerve palsy and Frey´s syndrome. However, limited parotidectomy requires an accurate pre-selection of patients and a precise preoperative diagnostic work-up. This manuscript describes the current trends in surgery for benign parotid lesions and illustrates the treatment options for major post-parotidectomy complications.

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.

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

BACKGROUND: Despite preservation techniques, performing a parotidectomy carries a transient facial nerve dysfunction rate in up to 65% of cases and a permanent facial nerve weakness rate of 4%-7%. METHODS: The lateral aspect of the face and neck was exposed in 5 cadaveric heads (10 sides). The relationship of the posterior auricular artery (PAA) and the facial nerve was studied and recorded and descriptive measurements were taken. RESULTS: In all specimens, the facial nerve trunk crossed the PAA inferior to the stylomastoid foramen and could be identified precisely by tracing the PAA proximally. The distance from the cross point of the PAA and the facial nerve to the external meatal cartilage was 5.2 ± 0.2 mm. CONCLUSION: The PAA represents a potential new anatomic landmark for facial nerve identification at the main trunk.