Reliability of Disposable Intraoperative Facial Nerve Stimulators

Facial nerve injury is one major morbidity of surgery performed along the course of this nerve. Surgeons frequently employ stimulators to identify and protect the nerve. Both disposable devices as well as larger, reusable stimulators are available. Despite their common use, relatively little documentation exists regarding the safety and reliability of these devices. We tested the electrical output of the four disposable, single-use motor nerve stimulators that are marketed in the United States. We found that each produced consistent stimulus output over time. One stimulator slightly exceeded the manufacturer's listed output while three devices produced significantly less voltage and current than specified by the manufacturer.     

Postparotidectomy facial nerve paralysis: possible etiologic factors and results with routine facial nerve monitoring.

OBJECTIVE: Analyze the incidence and factors responsible for postparotidectomy facial nerve paralysis when the surgery is performed with the routine use of facial nerve monitoring. STUDY DESIGN: A prospective, nonrandomized study. METHODS: Seventy consecutive patients underwent parotidectomy with intraoperative facial nerve monitoring. Two devices were used: a custom mechanical transducer and a commercial electromyograph-based apparatus. All patients were analyzed, including those with cancer and those with deliberate or accidental sectioning of facial nerve branches. The outcome variables were the motor facial nerve function according to the House-Brackmann grading scale (HB) at 1 week (temporary paralysis) and 6 to 12 months (definitive paralysis). Facial nerve grading was performed blindly from reviewing videotapes. RESULTS: The overall incidence of facial paralysis (HB>1) was 27% for temporary and 4% for permanent deficits. Most of the deficits were partial, most often concerning the marginal mandibular branch. Temporary deficits with HB scores of greater than 2 were only present in patients with parotid cancer or infection. Permanent deficits were present in three patients, including one patient with facial nerve sacrifice. Factors significantly associated with an increased incidence of temporary facial paralysis include the extent of parotidectomy, the intraoperative sectioning of facial nerve branches, the histopathology and the size of the lesion, and the duration of the operation. CONCLUSIONS: Despite a stringent accounting of postoperative facial nerve deficits, these data compare favorably to the literature with or without the use of monitoring. An overall incidence of 27% for temporary facial paralysis and 4% for permanent facial paralysis was found. Although the lack of a control group precludes definitive conclusions on the role of electromyograph-based facial nerve monitoring in routine parotidectomy, the authors found its use very helpful.     

Facial nerve dysfunction after parotidectomy: the role of local factors

OBJECTIVES/HYPOTHESIS: The objective was to analyze the incidence and factors associated with facial nerve dysfunction after conservative parotidectomy with facial nerve dissection. STUDY DESIGN: A retrospective unicentric study in a tertiary care center with prospective record of studied factors. METHODS: Over a 10-year period, 131 patients with normal facial nerve function underwent a superficial or total conservative parotidectomy with nerve dissection performed by one surgeon for primary benign or malignant tumors. Facial nerve function was assessed on the first postoperative day and at 1 month and 6 months after the parotidectomy. Extent of surgery, histopathological findings, tumor size, close contact of tumor with facial nerve, and sex and age of the patient were reviewed. These variables were studied in a chi2 statistical univariate and stratified analysis to determine their association with postoperative facial nerve dysfunction. RESULTS: Incidence of postoperative facial nerve dysfunction was 42.7% on the first postoperative day, 30.7% at 1 month after the parotidectomy, and 0% at 6 months after the parotidectomy. The most common dysfunction was paresis in a single nerve branch (48.2%), in particular, the marginal mandibular branch. Total parotidectomy was associated with a significantly higher incidence of facial nerve dysfunction during the first postoperative period (60.5% at day 1 and 44.7% at month 1) than superficial parotidectomy (18.2% at day 1 and 10.9% at month 1) (P < .001). In patients with total parotidectomy, close contact of the tumor with the facial nerve was found to have statistical causal relation with facial nerve weakness. In patients with superficial parotidectomy, inflammatory conditions were found as factors that increased postoperative facial nerve dysfunction. CONCLUSION: In the study series of conservative parotidectomies with facial nerve dissection, only extent of surgery and particular local conditions of nerve dissection, especially the close contact of tumor with facial nerve and inflammatory conditions, were found to be associated with postoperative facial nerve dysfunction.     

Operative technique for benign submandibular gland mass without identifying the mandibular branch of the facial nerve

Objective

The marginal mandibular branch of the facial nerve must be protected during surgery for benign diseases of submandibular gland. Methods for protecting the marginal mandibular branch include the nerve identification method and the non-identification method.

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

ObjectiveSurgery 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.MethodsWe 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.ResultsFactors 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.ConclusionThe 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.     

Facial nerve anatomy, dissection and preservation in lymphatic malformation management

OBJECTIVE: To describe facial nerve anatomy and surgical techniques used for safe lymphatic malformation resection of malformation involving the facial nerve. METHODS DESIGN: retrospective case series. Setting: tertiary pediatric hospital. Subjects: record review of lymphatic malformation patients after facial nerve dissection, from 1996 to 2005. Data collected included: facial nerve function, relationship of lymphatic malformation to facial nerve, facial nerve anatomy, dissection extent and clinical outcome. RESULTS: Sixteen patients who met inclusion criteria underwent a total of 21 facial nerve dissections. Mean age at dissection was 48 months (range 1-72 months). Mean follow-up was 38 months (range 8-144 months). Pre-operative lymphatic malformation stage by patient: II=7/16, III=4/16, IV=2/16 and V=3/16. Higher stage lymphatic malformations required more extensive dissections (p=0.026). Pre-operative facial nerve function was House-Brackmann grade (HBG)-1 in 20, and HBG-6 in 1. Eight months postoperatively, facial nerve function was HBG-1 in 18, HBG-2 in 1, and HBG-6 in 2. The facial nerve was surrounded by lymphatic malformation in 10/21, deep to the lymphatic malformation in 5/21, superficial to the lymphatic malformation in 4/21, and not identified in 2/21. Imaging studies predicted facial nerve position in 15/21 procedures. Antegrade nerve dissection was performed in 10/21, retrograde in 7/21 and not done in 2/21. Abnormally elongated facial nerve was identified in 11/21 cases and required more extensive dissection (p=0.040). Facial nerve monitoring was used in 15/21 dissections. Clinical outcomes were felt to be good in 19/21 dissections. CONCLUSIONS: In lymphatic malformation surgery, the facial nerve is often abnormally elongated and encompassed by malformation. Pre-operative imaging, facial nerve identification and dissection allow excellent postoperative facial nerve function.     

两种手术径路对颌下腺良性疾病面神经下颌缘支保护的效果分析

目的 对比分析两种不同手术途径对颌下腺良性疾病面神经下颌缘支的保护效果.方法 选择2014年12月-2018年6月在四川省肿瘤医院初次手术的134例颌下腺良性疾病患者,分别采用不同手术入路进行颌下腺全切术,术式1:颈阔肌下翻瓣显露面神经下颌缘支;术式2:不显露面神经下颌缘支,仅在颌下腺表面分离;术后均随访6个月以上,统...     

手术治疗面神经瘫痪病人27例

目的；探讨影响面神经瘫痪手术治疗效果的因素。方法：对２７例手术后病例进行疗效分析。结果：年龄小，手术早，进路合理，损伤轻及位置低的病例疗效满意；２１例术后疗效达Ｈｏｕｓｅ Ⅰ￣Ⅱ级（２１／２７），余６例为≥Ⅲ级，结论：认为根据不同病因及损伤范围选择合适的径路，充分探量，避免遗漏，是提高疗效的关键。     

Facial nerve monitoring in middle ear and mastoid surgery

HYPOTHESIS: Intraoperative electromyographic facial nerve monitoring, long accepted as the standard of care in surgery for acoustic neuroma and other cerebellopontine angle tumors, may be of aid in middle ear and mastoid surgery. STUDY DESIGN: Retrospective series of 262 cases of middle ear/mastoid surgery in which monitoring was performed by a neurophysiologist. METHODS: Neurophysiological monitoring events were classified as mechanical or electrical. The voltages producing facial nerve stimulation were compiled and compared with observed facial nerve dehiscence. RESULTS: The most common use of monitoring was localization of the facial nerve by electrical stimulation (60%) or identification of mechanically evoked activity (39%). In 57 cases (36%), the first electrical stimulation event evoked a facial nerve response at less than 1 V threshold, indicating little or no bony covering. The minimum stimulation threshold throughout each of these cases was less than 1 V in 88 of the 159 cases (55%) in which stimulation was attempted. In contrast, the facial nerve was visibly dehiscent in only 35 cases (13%). Neurophysiological monitoring confirmed aberrant facial nerve course through the temporal bone in four cases resulting in cancellation of surgical treatment in two cases. Postoperative facial nerve function was preserved in all cases when present preoperatively. CONCLUSIONS: An electrical stimulation threshold of less than 1 V is a more useful criterion of dehiscence than observation under the operating microscope. The absence of monitoring events allows safe dissection. Monitoring can help locate the facial nerve, guide the dissection and drilling, and confirm its integrity, thereby allowing more definitive surgical treatment while preserving neural function.     

Anastomoses between the cervical branch of the facial nerve and the transverse cervical cutaneous nerve

Head and neck surgeons must possess a thorough knowledge of facial nerve anatomy to avoid inducing iatrogenic injury during surgery. Anastomoses of the cervical branch (CB) of the facial nerve and the transverse cervical cutaneous nerve (TCCN) are poorly documented in our field. Knowledge of these anastomoses and their positions allows for (1) preservation of high CBs that contribute to lower lip depressor function, and (2) identification of the facial nerve in retrograde dissections. Our objective was to improve understanding of facial nerve anatomy by describing these anastomoses. The communicating branch between the TCCN and the CB was evaluated in 22 adult neck halves (11 cadavers). The facial nerve was exposed, and the CB was traced anteriorly. The TCCN was identified and traced superiorly to its anastomosis(es) with the CB. The distance from each anastomosis to the selected landmarks was recorded. Between the CB and the TCCN, 33 anastomoses were identified, with at least 1 anastomosis per hemineck and 2 anastomoses in 11 heminecks. Anastomoses were identified along the inferior border of the submandibular gland (SMG; 20 specimens) or posterior to the SMG (12 specimens). Five specimens had both anastomoses near the inferior border of the SMG, and 6 specimens had 1 anastomosis near the inferior border and 1 posterior to the SMG. Communication between the TCCN and the CB is regularly present. Its anatomic locations are either posterior to the SMG, often within the parenchyma of the parotid gland, or near the inferior border of the SMG. Awareness of these anastomoses allows a method for identification and preservation of the CB of the facial nerve as well as a starting point for retrograde facial nerve dissections.     

耳大神经移植修复面神经缺损的临床研究

目的:探讨采用耳大神经移植修复面神经缺损的可行性。方法:采用耳大神经移植修复面神经缺损14例,手术方式为经乳突进路面神经移植术。以House-Brackmann(HB)分级法评估手术前和手术后面神经功能。结果:在8例颞骨骨折所致面神经麻痹的患者中,颞骨骨折的类型均为纵形骨折,面神经受累及的部位主要在第2膝及其附近,术前面神经功能均为Ⅵ级。3例面神经肿瘤中面神经呈多节段受累,病理结果均为神经鞘膜瘤,术前面神经功能Ⅲ级1例、Ⅴ级2例。医源性损伤2例患者原发病均为胆脂瘤中耳炎,损伤部位分别为面神经乳突段和第2膝。1例钢水烧伤面神经损伤部位在面神经鼓室段,术前面神经功能Ⅵ级。除3例患者失访外,其余患者术后面神经功能恢复Ⅲ级4例、Ⅳ级3例、Ⅴ级2例、Ⅵ级2例。结论:颞骨骨折是导致面神经离断的最常见原因,以耳大神经移植修复面神经缺损是一种实用有效的方法,面神经移植后神经功能恢复最佳可达HBⅢ级。     

Intraparotid facial nerve schwannoma: management options

Intraparotid facial nerve schwannoma (FNS) is a very rare, benign tumour mimicking pleomorphic adenoma. Resection of this slow growing tumour may result in unnecessary facial nerve paralysis. The aim of this study is to present results of facial nerve schwannoma treatment at our institution and proposes a management plan. This is a retrospective case series of four patients, three male and one female with a mean age of 47.7 years who presented with a long-standing, asymptomatic parotid swelling. Two patients had facial weakness and underwent superficial parotidectomy, resection of tumour and facial nerve repair with a free graft from the greater auricular nerve. Two patients underwent biopsy without tumour resection. All tumours were confirmed histologically as facial nerve schwannomas. The mean follow up period was 3.5 years. Patients with resection of facial nerve schwannoma had a postoperative House Brackmann grade III and IV. Patients with biopsy had normal postoperative facial nerve function and the tumour did not grow significantly. No adverse effects or recurrence were reported. There is no preoperative diagnostic modality that can identify facial nerve schwannoma with certainty. Difficulty in locating the facial nerve intraoperatively raises suspicion of a neurogenous tumour of the facial nerve and this may prevent unnecessary damage to the nerve. Not every facial nerve schwannoma should be resected. This decision is based on (a) the extent of tumour (b) preoperative facial nerve function (c) best results achieved with nerve repair and (d) patient’s preferences. Large tumours with extension into the mastoid cavity or encroachment of sensitive structures and preoperative facial weakness are indications for surgical intervention. In most other cases, biopsy and observation suffices.     

面神经周围微血管丛分布的临床研究

目的为尽可能避免医源性面神经麻痹，评估面神经水平段周围微血管丛是否可以作为耳显微或耳神经外科术中面神经的定位标志。方法从2002年7月至2005年7月，共311例因慢性中耳炎、周围性面神经麻痹以及外耳道闭锁合并中耳畸形者，分别行开放式鼓室成形术（291例）、面神经减压术（10例）和先天性耳道闭锁和中耳畸形手术（10例）。观察和评估水平段面神经周围的微血管丛作为术中定位面神经的手术标志的有效性。结果在全部病例中，有95．8％的病例（298例）手术中可满意地观察到水平段面神经周围微血管丛，位于面神经鼓室段表面，仅4．2％的病例（13例）难以在水平段面神经周围发现该微血管丛。用面神经微血管判断水平段面神经管阳性率的95％可信区间为93．6％～98．0％。结论围绕在水平段面神经周围或表面的微血管丛，可作为术中及早且直接定位面神经的手术标志，用它来迅速确定面神经水平段是可靠的。     

Facial nerve paralysis following cochlear implant surgery

OBJECTIVES: Facial nerve paralysis is a rare but devastating complication of cochlear implant surgery. The aims of the study were to define the incidence of facial nerve paralysis in our series and understand possible mechanisms of injury. STUDY DESIGN: Retrospective chart review and case reports. METHODS: Charts were reviewed of all 705 patients implanted between 1980 and 2002 at the authors' institutions to identify those with postoperative facial nerve weakness and determine incidence. For patients with facial nerve weakness, onset, degree, and timing of paralysis were noted; clinical findings were correlated to operative report findings. The method of treatment was noted, and the final facial nerve function outcome was recorded. RESULTS: Five patients (one child and four adults) were found to have postoperative facial nerve weakness, for an incidence of 0.71%. This complication was delayed in all cases, ranging from 18 hours to 19 days postoperatively. All patients were treated with steroids or steroids combined with antiviral medication, and all ultimately recovered normal facial function. CONCLUSIONS: In the study series, the incidence of facial nerve paralysis following cochlear implant surgery was 0.71%. Possible mechanisms of injury included heating injury and viral reactivation. All patients presented with a delayed facial nerve paralysis and did recover normal facial nerve function.     

Facial nerve in parotidectomy: a topographical analysis

OBJECTIVE: Establish normative data concerning parotidectomy and facial nerve dissection and determine the relationship between the length of the facial nerve dissected during parotidectomy and subsequent facial nerve paresis. STUDY DESIGN: Prospective mapping of facial nerve during parotidectomy and comparison with postoperative facial nerve function. METHODS: A prospective observational study of 78 patients who underwent 79 parotidectomy procedures. During each procedure, various topographical measurements were recorded. These measurements included the distance from the tragal pointer to the main trunk of the facial nerve, the distance to the pes anserinus, and length of each segmental branch dissected. In addition, a designation of the patient's tumor location was made by drawing a line from the ear canal to the nasal spine. Tumors above this line were designated anatomic zone A and those below the line were designated anatomic zone B. Finally, facial nerve function was quantified at a 1-week follow-up visit using the House-Brackmann Scale. RESULTS: The distance from the main trunk of the facial nerve to the tragal pointer was significantly (P < .000) less than the previously accepted standard of 1 cm. The cervical and marginal mandibular branches had more nerve dissected, whereas the eye and forehead branches were the least dissected. Results of an independent t test and logistic regression (P = .01, both) indicated that patients with temporary facial nerve paresis had a significantly greater amount of nerve dissected than patients without temporary facial nerve paresis. Patients with short-term facial nerve dysfunction had significantly (P < .01) more total nerve dissected (136.73 mm vs. 94.73 mm) than patients without short-term facial nerve dysfunction. Patients with nerve dissection lengths at the third quartile (130.0 mm) were 3.8 times more likely to experience temporary facial nerve paresis than patients with nerve dissection lengths at the first quartile (64.5 mm). CONCLUSIONS: The axiom that the main trunk of the facial nerve is located 1 cm from the tragal pointer may need to be modified to less than 1 cm. The cervical and marginal mandibular branches had more nerve dissected, whereas the eye and forehead branches were the least dissected. Facial nerve paresis after parotidectomy is associated with the length of the facial nerve dissected during the procedure. The greater the length of facial nerve dissected, the higher the chance of facial nerve paresis, albeit temporarily, in this particular series of patients.     

术中面神经监测的动物实验与临床研究

目的：探讨术中面神经监测的参数与面神经减压术后面瘫的预后之间的关系。方法：对15只健康新西兰家兔30侧面神经及21例周围性面瘫患者进行术中面神经监测，术后随访6个月以上，使用χ^2检验评估术中监测的情况与减压术后面瘫的预后之间的关系。结果：15只家兔30侧面神经监测中不同个体的面神经阈值几乎均为0．05mA，在面神经的水平段、垂直段、颞骨外段其阈值也几乎均为0．05mA。21例面瘫患者，术中肌电图(EMG)引出者14例，其中13例减压术后面瘫的预后好，1例测舌差；EMG未引出者7例，其中1例减压术后面瘫的预后好，6例预后差。结论：术中面肌EMG的阈值能够较客观、稳定地评估面神经的功能。术中面肌EMG能否引出可以辅助预测面神经减压术后面瘫的预后情况，EMG能引出者预后好，反之则差。     

颞骨面神经鞘瘤显微手术预后因素分析

目的探讨影响颞骨面神经鞘瘤显微手术疗效的因素。方法回顾分析13例颞骨面神经鞘瘤患者的临床及随访资料，并运用统计软件SPSS10．0进行Spearman等级相关分析和非参数两独立样本Mann—WhitneyU检验。结果13例患者均接受显微外科手术治疗，11例同时接受了面神经重建，1例失访，接受随访者皆无肿瘤残留或复发，术后面神经功能达House-Brackman（HB）分级Ⅱ～Ⅴ。Spearman相关分析表明术后面神经功能分级与术前面神经麻痹持续时间（r=0．925，P〈0．01）和术前面神经功能分级（r=0．712，P〈0．05）相关。经非参数两独立样本Mann—Whitney U检验，发现面神经受累部位对面神经重建功能的影响无统计学意义（P〉0．05）。结论术前面神经麻痹持续时问越长和术前面神经功能越差，术后面神经功能越差；对于面肌已失神经支配，但仍存在面肌电图纤颤电位者，或高位面神经鞘瘤者，仍应考虑面神经重建。     

Sialoscintimetry in disorders of the facial nerve]

The comparative study of submandibular gland function before and after unilateral section of the chorda tympani, is used to verify the validity of sequential scintigraphy as a method of appraising the function of the salivary glands. Sequential scintigraphy of the submandibular glands was evaluated as a new, simple, and dependable test of the function of the submandibular glands, in topographical and prognostic assessment of 10 patients with unilateral idiopathic facial paralysis. The results of this neurodiagnostic test were compared and were found to be in close agreement with the results obtained by submandibular salivary flow measurement. The use of sequential scintigraphy of the submandibular glands constitutes a valuable tool in the clinical evaluation of patients with peripheral facial nerve disorders.     

Comparison of postoperative facial nerve outcomes between translabyrinthine and retrosigmoid approaches in matched-pair patients

OBJECTIVES/HYPOTHESIS: The objective was to assess whether the translabyrinthine approach for acoustic tumor removal offers better postoperative facial nerve function compared with the retrosigmoid approach. STUDY DESIGN: Retrospective case review from a tertiary otology referral center. METHODS: Patients who had undergone either retrosigmoid or translabyrinthine approach for removal of acoustic neuroma from January 1, 1980, to December 31, 1999, were included in the study. Two groups of patients were created, one containing retrosigmoid cases and the other, translabyrinthine. Attempts were made to match each retrosigmoid case to a translabyrinthine case with regard to tumor size, patient age, and date of operation. This matching served to eliminate these variables from influencing postoperative facial nerve outcomes. From an initial pool of 450 patients, 35 pairs of patients were matched for the study. Facial nerve functions were reported at immediate, 3-month, and 1-year postoperative periods. RESULTS: Patient demographics demonstrated that matched patients had almost identical tumor size, patient age, and date of operation. Comparisons of postoperative facial nerve functions between the matched groups revealed that retrosigmoid approach carried 2.86 times higher risk of facial nerve dysfunction during the immediate postoperative period. However, by 1 year, the facial nerve outcomes were similar between the two groups. CONCLUSION: Compared with the translabyrinthine approach, retrosigmoid approach carries a higher risk of postoperative facial nerve dysfunction during the immediate postoperative period. However, long-term facial nerve outcomes are identical between the two approaches.     

Management of facial nerve schwannoma in patients with favorable facial function

OBJECTIVE: We report six cases of facial nerve schwannomas in which surgical management allowed the preservation of facial nerve function. Specifically, this paper reports that a stripping surgery may provide favorable functional outcomes. STUDY DESIGN: A retrospective review of preoperative and postoperative data for six patients with facial nerve schwannoma that had normal facial nerve function or a House-Brackmann grade II facial palsy before the surgery. METHODS: Stripping surgery, which removed the schwannoma from the remaining nerve fascicle, was attempted on the six patients. Postoperative facial nerve function and imaging (magnetic resonance imaging) were evaluated. RESULTS: Stripping surgery with gross total tumor removal of the mass was performed in four cases. In the two remaining cases, the stripping surgery was not possible, and decompression alone was performed. Favorable preservation of facial function was achieved in all six cases. CONCLUSION: It was possible to preserve facial function after surgery to remove facial nerve schwannoma. We suggest that stripping surgery, focused on the preservation of continuity of the facial nerve, may be attempted for facial nerve schwannoma in which favorable facial function has been preserved.