Facial Nerve Schwannomas

A study of 26 patients with facial nerve schwannomas treated at the University Hospital of Zurich was done. The general clinical features are described, but particular emphasis is placed on tumor histologic findings, recovery of facial function after grafting, and the nature of intracranial facial nerve schwannomas Presenting symptoms are stratified by tumor location, with facial dysfunction being commonest with intracranial tumors, neurotologic symptoms being associated with intracranial tumors, and parotid masses being a feature of extratemporal tumors. We found no differences in tumor histology regardless of site of origin. Clinical, histologic, and radiologic evidence is reviewed, and from this evidence we conclude that intracranial facial nerve schwannomas may be particularly invasive acoustic schwannomas. Recovery of facial movement after grafting the facial nerve is not influenced by graft length or graft type. Prolonged preoperative facial dysfunction has a negative influence on recovery after grafting.     

Facial Nerve Neuroma Management

Three facial nerve neuromas were identified in the academic year 1994-1995. Each case illustrates different management dilemmas. One patient with a grade III facial nerve palsy had a small geniculate ganglion neuroma with the dilemma of decompression versus resection clear nerve section margins. The second patient underwent facial neuroma resection with cable graft reconstruction, but the permanent sections were positive. The last patient had a massive neuroma in which grafting versus other facial reconstructive options were considered. These three cases illustrate some of the major controversies in facial nerve neuroma management. We discuss our decision-making plan and report our results.     

周围神经纵向牵拉延长的实验研究

为研究周围神经牵拉延长的可能性及有可效性，进行了以下实验：（１）建立周围神经纵向牵拉延长的动物模型。选用２０只家兔，切断双侧正中神经。右侧为实验组，左侧为对照组。右侧正中神经的远端与邻近被切断肌腱的近端在同一平面牢固缝合，用银丝分别在缝接部及肱骨髁上作标记。实验侧术后每周摄片观察神经牵长的动态过程。３周后，根据Ｘ线片、神经外膜血供变化及组织学检查加以评估。结果显示：神经牵长率≥３０％，会明显增加神     

Intraoperative Facial Nerve Monitoring (IFNM) Predicts Facial Nerve Outcome after Resection of Vestibular Schwannoma

Summary Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB°I and °II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 μV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB°III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB°IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 μV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB°IV, respectively. Two patients with initial mHB°IV improved to mHB°III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.     

周围性面瘫面神经减压术病人的护理

总结25例周围性面瘫病人施行不同径路的面神经减压术前后的护理。结果除1例面瘫无明显变化外，其余手术效果良好。无严重并发症发生。提示护士根据痰病及手术特点。于手术前后与医生密切配合。进行针对性护理。是手术获得满意效果的重要保证。     

Facial Nerve Monitoring under Neuromuscular Blockade

The characteristics of facial nerve electromyography at various levels of neuromuscular blockade are unclear. Partial blockade is well known to facilitate anesthetic safety and management. However, the use of neuromuscular blockage in many skull base procedures is avoided to allow intraoperative facial nerve monitoring.We studied the influence of various levels of neuromuscular blockade on facial nerve stimulation in the New Zealand white rabbit. The facial nerve was exposed in the middle ear of six rabbits. Using electromyographic-type facial nerve monitor, we recorded the facial electromyography signals in these rabbits at increasing levels of vecuronium-induced neuromuscular blockade. All animals demonstrated reliable facial electromyography response at all levels of partial neuromuscular blockade (P < .02). Five of the six animals could be monitored throughout complete blockade. These results clearly demonstrate that rabbit facial electromyography monitoring is possible under neuromuscular blockade. The effect of neuromuscular blockers on facial electromyography monitoring deserves further study, as partial blockade would greatly facilitate the management of anesthesia in otologic, neurotologic, and skull base surgery.     

Facial Nerve Monitoring under Neuromuscular Blockade

The characteristics of facial nerve electromyography at various levels of neuromuscular blockade are unclear. Partial blockade is well known to facilitate anesthetic safety and management. However, the use of neuromuscular blockage in many skull base procedures is avoided to allow intraoperative facial nerve monitoring.

We studied the influence of various levels of neuromuscular blockade on facial nerve stimulation in the New Zealand white rabbit. The facial nerve was exposed in the middle ear of six rabbits. Using electromyographic-type facial nerve monitor, we recorded the facial electromyography signals in these rabbits at increasing levels of vecuronium-induced neuromuscular blockade. All animals demonstrated reliable facial electromyography response at all levels of partial neuromuscular blockade (P < .02). Five of the six animals could be monitored throughout complete blockade. These results clearly demonstrate that rabbit facial electromyography monitoring is possible under neuromuscular blockade. The effect of neuromuscular blockers on facial electromyography monitoring deserves further study, as partial blockade would greatly facilitate the management of anesthesia in otologic, neurotologic, and skull base surgery.

     

双神经转位恢复面部功能

不可逆的永久性面瘫会导致严重的后遗症,例如角膜溃疡、视力减退、口腔功能不全和面部不对称,给患者带来严重的社会心理压力。传统上可通过舌下神经或咬肌神经转位来修复不可逆性面瘫,这两种术式各有其优点和缺点:舌下神经转位能有效的恢复瘫痪侧面部的静息张力,然而在微笑时提供的口角偏移却是有限的;咬肌神经转位可以有效的恢复面部微笑,但提供给脸部的静息张力却很小。最近,美国斯坦福大学医学中心的Pepper博士介绍了将上述两种术式合二为一的双神经转位技术,通过将咬肌神经转位至面神经颊支来恢复面部的微笑表情,舌下神经转位至面神经第二膝区(介于面神经鼓室段与乳突段之间)来恢复面部张力。     

Facial Nerve Function after the Extended Translabyrinthine Approach

Objective To evaluate facial nerve function after excision of petroclival/anterior cerebellopontine angle (CPA) meningiomas by the extended translabyrinthine (EXTL) approach and compare these with outcomes after the transcochlear and transotic approaches. Design Retrospective chart review. Setting/Participants A search of archived surgical cases at a single institution between January 1, 1995, and January 1, 2012. Main Outcome Measures Facial function measured on the House-Brackmann (HB) scale. Results A total of 16 patients underwent the EXTL approach for primary excision of petroclival meningiomas. Average tumor size was 4.6 cm, and six patients had gross total resection. Average length of follow-up was 36.4 months. Two patients required reoperation for tumor regrowth. Preoperative facial function was HB I or II in all patients with available examinations. Immediate postoperative facial nerve function ranged from HB I to HB VI. In patients with an intact facial nerve at surgery, all but one had long-term facial function of HB I or II. A robust response on intraoperative facial nerve monitoring was prognostic of favorable long-term facial function. Facial function declined in some patients after postoperative radiation or revision surgery. Conclusions The EXTL approach allows excellent exposure of petroclival/anterior CPA lesions and should be favored to improve facial outcomes.     

Intracanalicular and Intratemporal Facial Nerve Schwannomas

Facial nerve schwannomas can mimic acoustic neuromas. We report herein two cases: a purely intracanalicular and an intratemporal facial nerve tumor extending into the internal auditory canal and the cerebellopontine angle. These tumors have to be suspected in patient with small-size tumors presenting with facial paralysis. We advocate translabyrinthine or middle fossa approach to facilitate nerve anastomosis. The establishment of the correct properative diagnosis is difficult, but the patient must be warned about the impossibility of preserving the facial nerve in these tumors.     

Intratemporal Grafting of the Facial Nerve following Lateral Skull Base Tumor Resection.

Intratemporal skull base tumors may invade the facial nerve in the horizontal (tympanic) or descending (vertical) segments, while parotid malignancies typically infiltrate the facial nerve at the stylomastoid foramen. This article will describe our results following intratemporal facial nerve grafting in 44 patients. Methods: This was a retrospective analysis of 44 patients requiring intratemporal facial nerve repair following lateral skull base tumor resection at our tertiary care, academic medical center. Results: Tumor histology included 17 parotid cancers, 13 temporal bone malignancies, 9 glomus tumors, 3 facial neuromas, and 2 endolymphatic sac tumors. The greater auricular nerve was used in 25 patients and the sural nerve was used in 19 cases. Forty patients were available for facial function assessment at 2 years. Using the House-Brackmann (H-B) recovery scale, the breakdown of patients by facial function was as follows: Grade I, 0 patients; Grade II, 4 patients; Grade III, 29 patients; Grade IV, 4 patients; Grade V, 3 patients; and Grade VI, 0 patients. Conclusions: Facial paralysis may occur from intrinsic or external lateral skull base invasion of the facial nerve. Intratemporal interposition grafting resulted in favorable facial function (H-B II or III) in 33 of the 40 (82.5%) patients at the 2-year assessment.