Preoperative Identification of Facial Nerve in Vestibular Schwannomas Surgery Using Diffusion Tensor Tractography

Objective

Facial nerve palsy is a common complication of treatment for vestibular schwannoma (VS), so preserving facial nerve function is important. The preoperative visualization of the course of facial nerve in relation to VS could help prevent injury to the nerve during the surgery. In this study, we evaluate the accuracy of diffusion tensor tractography (DTT) for preoperative identification of facial nerve.

Methods

We prospectively collected data from 11 patients with VS, who underwent preoperative DTT for facial nerve. Imaging results were correlated with intraoperative findings. Postoperative DTT was performed at postoperative 3 month. Facial nerve function was clinically evaluated according to the House-Brackmann (HB) facial nerve grading system.

Results

Facial nerve courses on preoperative tractography were entirely correlated with intraoperative findings in all patients. Facial nerve was located on the anterior of the tumor surface in 5 cases, on anteroinferior in 3 cases, on anterosuperior in 2 cases, and on posteroinferior in 1 case. In postoperative facial nerve tractography, preservation of facial nerve was confirmed in all patients. No patient had severe facial paralysis at postoperative one year.

Conclusion

This study shows that DTT for preoperative identification of facial nerve in VS surgery could be a very accurate and useful radiological method and could help to improve facial nerve preservation.     

Preservation of Facial Nerve Function Repaired by Using Fibrin Glue-Coated Collagen Fleece for a Totally Transected Facial Nerve during Vestibular Schwannoma Surgery

Recently, the increasing rates of facial nerve preservation after vestibular schwannoma (VS) surgery have been achieved. However, the management of a partially or completely damaged facial nerve remains an important issue. The authors report a patient who was had a good recovery after a facial nerve reconstruction using fibrin glue-coated collagen fleece for a totally transected facial nerve during VS surgery. And, we verifed the anatomical preservation and functional outcome of the facial nerve with postoperative diffusion tensor (DT) imaging facial nerve tractography, electroneurography (ENoG) and House-Brackmann (HB) grade. DT imaging tractography at the 3rd postoperative day revealed preservation of facial nerve. And facial nerve degeneration ratio was 94.1% at 7th postoperative day ENoG. At postoperative 3 months and 1 year follow-up examination with DT imaging facial nerve tractography and ENoG, good results for facial nerve function were observed.     

Staging in Vestibular Schwannoma Surgery: A Modified Technique

The authors herein propose the staged excision as a novel strategy to preserve facial nerve and minimize complication during microsurgery of large vestibular schwannoma (VS). At the first stage, for reducing mass effect on the brain stem and cerebellum, subtotal tumor resection was performed via a retrosigmoid craniotomy without intervention of meatal portion of tumor. With total resection of the remaining tumor, the facial nerve was decompressed and delineated during the second stage translabyrinthine approach at a later date. A 38-year-old female who underwent the staging operation for resection of her huge VS is illustrated.     

面神经在大型听神经瘤中的分布变化规律

目的 探讨大型听神经瘤术中面神经与听神经瘤的相对解剖位置及规律.方法 通过同顾性分析133例大型听神经瘤的手术录像,分析面神经在听神经瘤的中的分布变化规律.结果 面神经在脑干端和内听道基底部的位置相对固定,在可识别面神经的病例中,在内听道口前上部有35例(26%),前下部的89例(67%),后下部6例(5%).在小脑脑桥角池中段位于肿瘤前上方11例(8%),前中部49例(37%),前下部63例(47%),后下部6例(5%).结论 掌握面神经在大型听神经瘤中的分布规律可以提高面神经的保护.     

Facial nerve palsy after vestibular schwannoma surgery: Dynamic risk-stratification based on continuous EMG-monitoring

ObjectiveA-trains are a pathological pattern in intraoperative EMG-monitoring. Traintime, a parameter calculated by automated EMG-analysis, quantifies A-train activity. Its extent is associated with the degree of postoperative facial nerve palsy. However, false positive results have been observed. A systematic flaw in automated analysis was hypothesized.MethodsFacial nerve EMG-data from 79 patients undergoing vestibular schwannoma surgery were analyzed visually. Automated traintime was compared with these results. The progressive risk for postoperative paresis was calculated with respect to traintime (visual and automated).ResultsAutomated analysis identified a small (1.46%), but highly representative fraction of overall A-train activity: Pearson’s correlation coefficient between both values was 0.944 (p < 0.001). Both were correlated with clinical outcome in a highly significant way (p < 0.001) with Spearman’s Rho 0.592 (automated) and 0.563 (visual). Progressive risk development was visualized as an inverse sigmoid curve with traintime on a logarithmic scale.ConclusionsAutomated traintime is a representative and reliable expression for overall A-train activity. As risk-development is complex, rigid thresholds are problematic.SignificanceIndividual risk for postoperative palsy can be estimated on the basis of the calculated curve presented. This approach is of higher practical value than a rigid (and low) threshold.     

Recurrence rate,time to progression and facial nerve function in microsurgery of vestibular schwannoma

Abstract

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Objective: Recurrence rate, time to progression, and facial nerve function were analysed by comparing patients with complete and near total tumor removal after suboccipital craniotomy for vestibular schwannoma surgery.

Methods: From 1996 to 2004, 118 patients with vestibular schwannoma were operated with an interdisciplinary approach. Fifty patients fulfilled the inclusion criteria and were included in the study. Progression was defined as an increase of 2 mm in the largest diameter in the magnetic resonance imaging. Preoperative tumor size, facial nerve function estimated using the House-Brackmann score (HBS), time to progression, and recurrence rate were analysed and related to the extent of resection.

Results: In 28 cases (group I), a capsular remnant was left. In 22 cases (group II), tumor removal was complete. In group I, nine patients (32·1%) showed progression. In group II, two patients (9·1%) developed a recurrent tumor, no significance (P = 0·085). In groups I and II, 53·6 and 59·6% had a good function of the facial nerve (HBS I+II), 28·6% in group I and 13·5% in group II had a moderate disturbance (HBS III+IV), and 17·9% in group I and 27·7% in group II had a poor function (HBS V+VI). There was no significant difference between median preoperative tumor size and facial nerve function within patients with HBS III and IV.

Conclusion: Complete tumor removal may be associated with a risk of functional loss, whereas near total tumor removal may be associated with a higher risk of progression.     

神经导航下内听道及面神经管的解剖研究

目的探讨神经导航系统在内听道及面神经管解剖研究中的作用;为经乙状窦后入路手术中安全打开内听道及经岩骨入路手术中保护面神经管提供解剖依据。方法用8具16侧成人汉族尸头标本在神经导航指引下完成经乙状窦后入路手术中到达内听道及经岩骨入路的手术操作,测量导航误差;观测内听道及面神经管的解剖及其与重要结构的关系。结果①所有内听道及面神经管均成功导航,成功率100%,总体误差<0.9mm。②内耳门后下缘到乙状窦后缘中点的距离左侧为(32.15±1.76)mm,右侧为(33.34±1.57)mm;到后半规管后缘中点的距离左侧为(12.51±2.15)mm,右侧为(13.26±2.44)mm。③面神经管岩骨段可划分为三段:前庭段最短,长径(3.6±1.2)mm,管径平均为(1.2±0.3)mm;鼓室段居中,长径(11.2±2.5)mm,平均管径(1.4±0.1)mm;乳突段最长,长径(16.1±3.6)mm,平均管径为(1.7±0.2)mm。结论神经导航辅助对打开内听道及保护面神经管有肯定的价值;熟悉内耳门、面神经管及周围结构的显微解剖有助于手术中保护重要结构。     

大型听神经瘤的手术治疗方法

目的探讨在术中神经电生理监测下经枕下-乙状窦后入路显微手术切除大型听神经瘤的方法及效果。方法回顾性分析2013年1月至2015年10月收治的85例大型听神经瘤的临床资料,均在术中神经电生理监测下,采取直切口乙状窦后入路小骨窗显微手术切除肿瘤。结果肿瘤全切除76例(89.4%),次全切除9例(10.6%);术中面神经解剖保留80例(94.1%)。术后即刻、7 d、3个月、6个月、9个月、1年面神经功能分级优良率(H-B分级Ⅰ~Ⅱ级)分别为88.2%、56.0%、41.9%、50.9%、68.6%、86.7%。结论在术中神经电生理监测下显微手术治疗大型听神经瘤,可更好保护面神经功能,提高术后生活质量。     

内听道后壁磨除在前庭神经鞘瘤显微手术治疗中的作用

目的评价内听道后壁磨除对于处理前庭神经鞘瘤内听道内肿瘤的效果。方法回顾性分析自2003年1月至2006年12月,经内听道入路连续显微手术治疗的103例前庭神经鞘瘤。结果术后CT显示部分内听道后壁磨除组从内听道底平均内听道后壁缩短至4.6mm±1.0mm（n=48）;55例内听道后壁广泛磨除组,内听道后壁平均残留1.9mm±0.5mm（从内听道底起）。迷路的解剖位置位于S-F线外侧者52例,位于S-F线上者23例,位于S-F线内侧者28例。术后没有出现与手术有关的永久性并发症,死亡率为0%。结论显微内听道（IAM）后壁磨除在前庭神经鞘瘤切除过程中可提供更好的外科手术入路。     

Microanatomy and Histological Features of Central Myelin in the Root Exit Zone of Facial Nerve

Objective

The aim of this study was to evaluate the microanatomy and histological features of the central myelin in the root exit zone of facial nerve.

Methods

Forty facial nerves with brain stem were obtained from 20 formalin fixed cadavers. Among them 17 facial nerves were ruined during preparation and 23 root entry zone (REZ) of facial nerves could be examined. The length of medial REZ, from detach point of facial nerve at the brain stem to transitional area, and the thickness of glial membrane of central myelin was measured. We cut brain stem along the facial nerve and made a tissue block of facial nerve REZ. Each tissue block was embedded with paraffin and serially sectioned. Slices were stained with hematoxylin and eosin (H&E), periodic acid-Schiff, and glial fibrillary acid protein. Microscopy was used to measure the extent of central myelin and thickness of outer glial membrane of central myelin. Thickness of glial membrane was examined at two different points, the thickest area of proximal and distal REZ.

Results

Special stain with PAS and GFAP could be differentiated the central and peripheral myelin of facial nerve. The length of medial REZ was mean 2.6 mm (1.6-3.5 mm). The glial limiting membrane of brain stem is continued to the end of central myelin. We called it glial sheath of REZ. The thickness of glial sheath was mean 66.5 µm (40-110 µm) at proximal REZ and 7.4 µm (5-10 µm) at distal REZ.

Conclusion

Medial REZ of facial nerve is mean 2.6 mm in length and covered by glial sheath continued from glial limiting membrane of brain stem. Glial sheath of central myelin tends to become thin toward transitional zone.     

Management of vestibular schwannomas in young patients—comparison of clinical features and outcome with adult patients

Objects Vestibular schwannomas (VS) in young patients are rare. They are regarded to have different biological characteristics. Our objective is to analyze a series of such patients, with respect to their clinical presentation, treatment, and outcome and to compare the results to a matched series of adult patients. Materials and methods Retrospective analysis of 20 patients under 21 years of age. All patients underwent surgery via the retrosigmoid approach. The analysis included: age, gender, tumor size, clinical, and neurological pre- and postoperative status including cochlear and facial nerve function, and complications. Statistical comparison of the young patient’s data with a series of 200 adult patients previously published by the authors. Conclusions The current study demonstrates that the outcome after surgical management in patients harboring VS does not show any significant difference between young and adult patients.     

面神经瘤5例报告并文献复习

目的探讨面神经瘤手术方法、面神经保留及重建方法的选择与面神经功能恢复的关系。方法5例面神经瘤均行肿瘤切除术,2例神经纤维瘤和1例神经鞘瘤术后复发再次手术;1例面神经保留,3例面神经重建,1例面神经成形术。结果5例面神经瘤中神经鞘瘤3例和神经纤维瘤2例,均手术全切除。5例面神经功能按House分级法评估:Ⅰ级1例,Ⅱ-Ⅲ级2例,Ⅲ级1例,V级1例。结论面神经重建应取积极态度,争取一期手术,延期手术应在面肌萎缩前6～8个月内进行。     

低水平神经肌肉阻滞状态下听神经瘤切除术中面神经的保护

目的在低水平神经肌肉阻滞状态下进行听神经瘤切除术中面神经的保护。方法28例大、中型听神经瘤患者行听神经瘤切除术,术中应用AXONEpochXP神经电生理工作站,根据4个成串刺激(train of four stim-ulation,TOF)和脑电图(EEG)分别监测肌松程度和麻醉深度,在肿瘤切除过程中通过调节肌松药物和麻醉药物剂量使T4/T1维持在25%～50%,术中监测眼轮匝肌、口轮匝肌、咬肌和斜方肌自由描记肌电图和诱发肌电图,分别反应面神经、三叉神经和副神经功能。于术后1周和术后第6个月分别评估面神经功能。结果28例患者术中均成功探测到面神经走行,电刺激强度为0.1～0.3mA,术中无患者发生体动情况。术后面神经功能保留率良好,术后1周面神经House-Brackmann(H-B)功能分级为Ⅰ级者5例、Ⅱ级者13例,Ⅲ级者8例,Ⅳ级者2例;至术后6个月面神经H-B功能分级Ⅰ级者10例,Ⅱ级者12例,Ⅲ级者5例,Ⅳ级者1例。结论在听神经瘤手术过程中通过电生理监测对面神经进行保护,需要电生理、麻醉和手术医生的配合。在低水平神经肌肉接头阻滞状态下,完全可以达到确保手术安全进行及保护面神经功能的目的。     

面神经颞支的体表定位与走行层次研究

目的通过体表标志区对面神经颞支走行进行平面区域定位与穿行层次分析,为相关手术预防颞支损伤提供解剖学标记范围。方法对12具经福尔马林防腐处理后成人尸头标本进行大体和显微解剖,观测并记录跨经耳屏水平线、耳屏点-外眦连线、耳上基点-眉外端连线的面神经颞支数和位置,记录穿行于颞浅筋膜上脂肪垫、筋膜间脂肪层、颞肌深筋膜下脂肪层的颞支支数。保存拍摄的数码照片并进行图片分析。结果颞支在三条标志线上的分支数及最后支至最前支的位置分别为:跨经耳屏水平线(2.6±0.7)支,耳屏前(21.46±2.34)～(30.18±5.88)mm;跨经耳屏点-外眦连线(6.5±2.2)支,耳屏点前(24.26±5.64)～(37.98±8.90)mm;跨经耳上基点-眉外端连线(5.3±1.5)支,耳上基点前(35.68±10.46)mm。面神经颞支在筋膜间脂肪垫层有相当数量的穿行支(16/62支)。结论面神经颞支的颞部行程可通过体表标志线进行平面区域定位,并可针对手术解剖划分为“危险区”和“相对危险区”。翼点手术行颞肌筋膜下分离可最大程度地防止面神经颞支的损伤。     

大型听神经瘤显微手术保存面神经功能的治疗体会

目的总结53例大型听神经瘤患者显微切除术后近、远期疗效，探讨手术中、术后如何最大可能的保存面神经功能。方法我们对1995-2005年收治的53例大型听神经瘤患者从切口设计、分离方法、术后管理等多方面采取改进措施，提高治疗质量，术后患者进行6个月至10年以上随访．观察面神经功能恢复的情况。结果53例全部解剖保存了面神经：术后除部分患者不同程度面瘫外无明显其它手术直接并发症；经6个月至10年以上随访，48例患者面神经功能有不同程度的恢复，18例恢复至基本正常。结论即使是大型听神经瘤。只要手术方法适合．术后管理得当，面神经功能保存也是可能的。     

Quality of life in patients of unilateral vestibular schwannoma treated with microsurgery: A South-Asian tertiary care Hospital experience

Majority of the published literature on the impact of microsurgery over quality-of-life (QOL) in vestibular schwannoma (VS) patients is retrospective in nature, with variable results, and there has been very little contribution from South-Asia. The authors designed this study to investigate the role of microsurgery in QOL alterations in VS patients, and to compare obtained QOL scores with that of control population. Between February 2017 and March 2018, a prospective/retrospective study was done at our institute. Prospective and retrospective cohorts included, 30 and 34 consecutive patients, respectively, of unilateral VS undergoing microsurgery. QOL assessment was done using Short Form-36 (SF–36), and the Penn Acoustic Neuroma Quality-Of-Life (PANQOL) questionnaires. Prospective cohort underwent QOL assessment at 3 junctures – pre-surgery, 3-months & 1-year post-surgery; while retrospective cohort was assessed only once, at 1-year post-surgery. Age- & sex- matched normal population and diabetic patients were used as controls. In the prospective cohort, patients showed drop in all PANQOL domain/ SF-36 dimension scores at 3-month post-surgery, exception being vitality and general health in SF-36; showed improvement at 1-year follow-up, with majority either levelling or improving their respective pre-surgery scores. Gross total resection, tumors ≤ 3 cm, and age ≤ 45 years had better PANQOL scores at 1-year post-surgery across all the domains. Patients in both the cohorts showed worse QOL compared to normal population, but the gap got narrower at 1-year post-surgery. Our study adds a South-Asian perspective to the pool of prospective knowledge available on QOL following microsurgery in VS patients.