A Review of Facial Nerve Outcome in 100 Consecutive Cases of Acoustic Tumor Surgery

Objective To determine the facial nerve outcomes at a tertiary neurotological referral center specializing in acoustic neuroma and skull base surgery. Study Design Retrospective review of 100 consecutive patients in whom acoustic neuromas were removed using all of the standard surgical approaches. Methods Functional facial nerve outcomes were independently assessed using the House‐Brackmann facial nerve grading system. Results The tumors were categorized as small, medium, large, and giant. If one excludes the three patients with preoperative facial palsies, 100% of the small tumors, 98.6% of the medium tumors, 100% of the large tumors, and 71% of the giant tumors had facial nerve function grade I‐II/VI after surgery. Conclusion Facial nerve results from alternative nonsurgical treatments must be compared with facial nerve outcomes from experienced surgical centers. Based on the facial nerve outcomes from our 100 consecutive patients, microsurgical resection remains the preferred treatment modality for acoustic tumors.     

Facial reanimation after acoustic neuroma excision: the patient's perspective

Facial reanimation after acoustic neuroma excision is currently accomplished using a variety of surgical techniques. A multi-institutional survey of patient perceptions of facial reanimation success was accomplished by mailing a questionnaire to 809 randomly selected members of the Acoustic Neuroma Association. Four hundred sixty patients who underwent 296 reanimation procedures responded. Facial to hypoglossal nerve anastomosis, tarsorrhaphy, and upper eyelid implants were most frequently performed. The patient's estimations of initial deficit, spontaneous recovery, and overall satisfaction with the reanimation procedures are discussed.     

Endoscope-Assisted Cerebellopontine Angle Surgery

Objective To report experiences with use of otoendoscopy in cerebellopontine angle (CPA) surgeries. Methods Twenty five cases of CPA surgeries performed between November 2002 and December 2008 in which microscope enabled otoendoscopy was used were reviewed.The 25 cases included 19 cases of acoustic neuroma, 3 cases of CPA facial nerve tumors, 1 case of trigeminal neurinoma, a case of glossopharyngeal neuralgia and 1 case of hemifacial spasm. Endoscopy was used in all cases together with monitoring of brainstem auditory responses and facial electromyography. Postoperative hearing and facial nerve function were evaluated and compared to pre-op-erative levels. Results Endoscopy provided improved visualization of local anatomy, revealed hidden lesions and reduced unnecessary anatomical distortions. Total resection was achieved in 18 of the 19 acoustic neuroma cases, Facial nerve anatomical integrity was preserved in all 19 cases. One week postoperative House-Brackmann grading was Ⅰ in 3 cases, Ⅱ in 10 cases and Ⅲ in 6 cases. Facial nerve function continued to improve in some cases at 3 months. Total tumor resection was achieved in all 3 patients with facial neurinoma. The facial nerve was sacrificed in 2 of the 3 cases with primary faciohypoglossal nerve anastomosis. Facial nerve function was Grade Ⅱ and Grade Ⅲ one year after surgery, respectively. In the case with anatomically preserved facial nerve, postoperative facial nerve function was initially Grade Ⅲ and improved to Ⅱ at 3 months. The tumor was completely resected in the trigeminal neurinoma patient with a Grade Ⅲ postoperative facial nerve function which improved Grade Ⅱ three months later. Seventeen of the 19 patients with acoustic neuroma retained hearing postoperatively, of these 12 maintained preoperative levels of hearing. Preoperative hearing capacity was preserved in 2 of the 3 patients with facial nerve tumors, but lost in patients with other tumor types. Glossopharyngeal neurotomy (n=1) and mi-crovascular deeompression(n=1) resulted in satisfactory symptom relief and no recurrence at 5- and 3-year follow up, respectively. Conclusions Otoendos aope-aided technique greatly helps surgical management of CPA and in-ternal auditory canal lesions and other disorders. This minimally invasive technique overcomes many shortcomings inherent to the traditional retrosigmoid approach.     

大型听神经瘤的显微手术技巧及面神经保护

目的探讨大型听神经瘤的显微手术技巧、效果及术中面神经的保护。方法回顾性分析解放军总医院耳鼻咽喉头颈外科2010年1月~2010年12月收治的采用显微外科手术治疗30例大型听神经瘤患者的临床资料。其中男性18例,女性12例;年龄19～71岁,平均39.6±4.2岁;病程3个月～2年。主要临床表现为桥小脑角综合征和颅内压增高征,首发症状表现为耳鸣、听力下降12例,头痛、恶心、呕吐10例,行走不稳4例,面部麻木7例,三叉神经痛2例,面瘫6例。30例术中均行面神经监测,显微镜下切除肿瘤,术毕刺激面神经的脑干端对术后面神经功能进行预测。结果本组30例大型听神经瘤全切除28例,次全切除1例,部分切除1例。术中面神经完整保留29例(96.67%),无死亡病例。肿瘤切除后,面神经刺激阈值的大小与术后面神经功能存在明显的相关性。刺激阈值越小,术后面神经功能越好。结论熟练地采用显微外科技术选择合适的手术入路可明显提高肿瘤的全切除率和面神经的解剖及功能保留率。手术入路的正确选择,娴熟的显微外科操作技术,术中应用面神经监测技术,能有效地保护桥小脑角周围的重要结构及面神经功能,并可预测术后面神经功能。     

The facial nerve in acoustic tumor surgery

The results of facial nerve function in twenty-four cases of acoustic neuroma removal using translabyrinthine approach from 1982 to 1987 were reported. Facial nerve had been paralysed in one case preoperatively. The facial nerve function were preserved in 21 out of 23 cases (91.3%). The appearance of facial nerve during surgery was as follows: normally located in 9 cases, displaced and deformed in 12 cases and invaded by the tumor in 3 cases. The size and location of the tumor determine the chance of preservation of facial nerve function. The procedures of manipulating the facial nerve and preventing the injury to the facial nerve during surgery were discussed in detail.     

Facial nerve recovery after acoustic neuroma removal

A retrospective analysis of 76 patients who underwent acoustic neuroma removal is reported. Facial nerve function prior to surgery and tumour size are assessed with respect to final facial nerve recovery and the need for surgical rehabilitation. Both pre-operative facial weakness and tumour size greater than 2.5 cm. are shown to be predictive factors of poor facial nerve recovery. Multiple surgical rehabilitative procedures are often required when inadequate function and/or cosmetic results are obtained. Primary nerve repair and facial-hypoglossal anastomosis give better rehabilitative results than dynamic and static procedures. The association of tumour size greater than 2.5 cm. with increased risk of poor facial recovery re-emphasizes the need to detect and remove acoustic neuromas at an early stage.     

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.     

Magnetic resonance imaging of facial nerve neuromas

Facial nerve neuromas are uncommon tumors often confused with other tumors of the temporal bone and cerebellopontine angle. Radiologically, it may be impossible to differentiate an intracanalicu-lar facial nerve neuroma from an acoustic neuroma. We present three case reports of facial nerve neuromas arising within the internal auditory canal to show the important magnetic resonance imaging features of these tumors. One tumor extended into the cerebellopontine angle, middle cranial fossa, and middle ear. Another filled the internal auditory canal and extended through the cerebellopontine angle to the brain stem. The third occurred in a patient who had neurofibromatosis as well as numerous other intracranial tumors. We feel that gadolinium-enhanced magnetic resonance imaging provides the most useful information in the preoperative assessment of this disorder.     

神经电生理监测下听神经瘤显微手术中面神经的保护

目的总结分析术中神经电生理监测结合显微手术操作技巧在听神经瘤手术中预防面神经损伤的作用。方法选取我科2011～2012年施行乙状窦后入路显微手术的大型及中型听神经瘤（肿瘤直径≥2.4 cm）患者62例,术中应用神经电生理监测技术对手术进行综合监护,同时密切留意骨性解剖、蛛网膜解剖、神经与血管解剖关系。术后随访6个月,评估肿瘤切除程度并根据House-Brack-mann面神经功能分级对患者面神经功能进行评估。结果肿瘤全切除58例（93.5%）,次全切除4例（6.5%）;无围手术期死亡患者。面神经功能评定：Ⅰ级57例（91.9%）,Ⅱ级5例（8.1%）。结论对于大型和中型听神经瘤患者,术中进行综合电生理监护,同时操作时注意典型的解剖位置与熟练的显微手术技术,可达到较高的肿瘤全切除率,并尽可能地保全面神经功能。     

Electrical evaluation of the facial nerve in acoustic neuroma patients: preliminary comparison between transcranial magnetic coil stimulation and electroneurography.

Subclinical involvement of the facial nerve by acoustic neuromas may be identified preoperatively using conventional electroneurography (ENoG). The clinical application of extratemporal stimulation distal to the stylomastoid foramen is limited in these cases by the more proximal site of the lesion. Transcranial magnetic coil stimulation (MCS) is a noninvasive means by which the facial nerve is stimulated at the level of the motor cortex or the brain stem, before it enters the internal auditory canal. Topographically such an assessment may have more diagnostic relevance than other forms of electrical stimulation in acoustic neuroma patients. To test this theory the facial nerves of 20 patients with acoustic neuromas were stimulated using ENoG and MCS preoperatively and 1 week postoperatively. Stimulation parameters were comparable and included threshold and suprathreshold levels of stimulation while compound action potential amplitudes and early and late response latencies were monitored. Facial nerve function was assessed clinically using the Stennert grading system. All the patients had clinically normal facial nerve function preoperatively. Normative data suggested a close correlation between threshold and suprathreshold amplitudes generated by both ENoG and MCS. To the contrary, in the pathologic ears there was a higher incidence of stimulus response abnormality determined by MCS than by ENoG. A comparison of these data, tumor size, and postoperative results promotes further evaluation of MCS as a prognostic index in acoustic neuroma patients.     

Facial reanimation by cross-facial nerve grafting: report of five cases

Facial nerve repair is a dynamic reanimation technique. Direct nerve repair by suturing or grafting can provide good results within a specific time frame. Immediate nerve repair has been successful in cases of laceration injuries, but nerve grafting techniques are typically delayed when it is clear that direct suturing to the nerve trunk cannot be achieved without tension. Delayed nerve grafting is also employed following ablative procedures and in cases of trauma that cause segmental nerve deficits. Cross-facial nerve grafting is particularly useful when the peripheral branches are intact and the main trunk of the facial nerve is inaccessible. This method is also typically performed in a delayed fashion. Rehabilitation of the facial nerve and subsequent reinnervation of the mimetic motor endplates are achieved through axonal growth. In this article, we describe a consecutive series of five patients who developed facial paralysis following cranial surgery for acoustic neuroma. Each underwent successful cross-facial nerve grafting during the first week following their initial surgery. Each received a sural nerve graft to at least two main divisions of the VIIth cranial nerve. We discuss our operative technique and the degree of restored nerve function.     

听神经瘤患者术前面神经及耳蜗神经显影技术

听神经瘤是最常见的桥小脑角良性肿瘤,手术可引起面瘫、听力下降等并发症,术前定位面神经、耳蜗神经可降低其发生率。本文对近年来发展的颅内神经显影技术做一综述,主要集中于听神经瘤患者的面神经、耳蜗神经定位手段。     

Facial nerve neuroma Report of two cases including histological and radiological imaging studies

Unlike the acoustic neuroma, a facial nerve neuroma is an uncommon finding, even in referral clinical centers. Two cases of facial nerve neuromas are presented, with special focus on the importance of adequate radiological imaging techniques and histological characteristics of tumor specimens. Surgical modalities regarding tumor removal as well as facial nerve repair are discussed and the current world literature reviewed.Presented at the February meeting of the Belgian Society of Otorhinolaryngology and Cervicofacial Surgery, 20 February 1993, Brussels, Belgium     

Distance from acoustic neuroma to fundus and a postoperative facial palsy.

OBJECTIVE/HYPOTHESIS: Generally, patients with small acoustic neuroma have less facial palsy after its removal. The middle cranial fossa approach is mainly applied to the small acoustic neuroma and tumor size does not influence the prognosis of facial palsy. The internal auditory canal cannot be fully opened in the middle cranial fossa approach, and the facial nerve is tightly attached in the fundus. According to these anatomical factors, we hypothesized that acoustic neuromas located away from the fundus might be removed with less facial nerve damage. We investigated the distance between the acoustic neuroma and fundus and its clinical relationship. STUDY DESIGN: Retrospective study of 45 patients with acoustic neuroma who underwent a middle cranial fossa approach. METHODS: The distance between the acoustic neuroma and fundus and the tumor diameter were measured on T2-weighted and contrast-enhanced magnetic resonance images, respectively. These data were compared with the postoperative facial nerve function. RESULTS: The mean distance was 3.0 +/- 1.8 mm (range, 0-10 mm), and the mean diameter was 11.3 +/- 3.7 mm (means +/- standard deviation; range, 4-20 mm). Neither the distance nor the diameter had any correlation to the degrees of postoperative facial palsy either immediately or at 3 months after surgery. CONCLUSIONS: As far as the nerve was anatomically preserved, postoperative facial nerve function seemed to be influenced by factors other than surgical manipulation among small acoustic neuromas. Although the tumor fills in the fundus, it may not influence postoperative facial nerve function and also may not interfere with indication of the middle cranial fossa approach for removal of the acoustic neuroma.     

Neurophysiologic intraoperative monitoring: II. Facial nerve function

Intraoperative facial nerve monitoring provides a potentially useful adjunct to recent surgical advances in neurotology and neurosurgery. These measures further aid the surgeon in preserving facial nerve function by enhancing visual identification with electrical monitoring of mechanically evoked facial muscle activation. Facial nerve monitoring in neurotologic surgery may achieve the following goals: (1) early recognition of surgical trauma to the facial nerve, with immediate feedback made available to the surgeon through monitoring of mechanical activation; (2) assistance in distinguishing the facial nerve from regional cranial nerves and from adjacent soft tissue and tumor with selective electrical stimulation; (3) facilitation of tumor excision by electrical mapping of portions of tumor that are remote from the facial nerve; (4) confirmation of nerve stimulability at the completion of surgery; and (5) identification of the site and degree of neural dysfunction in patients undergoing nerve exploration for suspected facial nerve neoplasm or undergoing decompression in acute facial palsy. This paper provides an overview of intraoperative facial nerve monitoring principles and methodology and reports a recent clinical investigation that demonstrates the utility of facial nerve monitoring in translabyrinthine acoustic neuroma surgery.     

Facial nerve neuroma: diagnosis and management

Facial neuroma is a condition of insidious onset. Prior to the introduction of modern imaging techniques (computerised tomography, magnetic resonance imaging) delays between presentation and diagnosis were common place. Atypical facial paralysis and hearing loss are the most common presenting features. This combination is very suggestive of a facial neuroma and is an indication to proceed to computed tomography. This investigation can reveal expansion of the Fallopian canal at any point through the temporal bone. A few facial neuromas occur in the cerebello-pontine angle alone or in the parotid. Resection and grafting are always worthwhile as facial neurones seem to persist in the tumour mass keeping muscle alive until the facial nerve graft becomes functional. The presentation, management and results of treatment of 15 such cases is presented.     

Primary tumor of the facial nerve: Diagnosis and management

Benign primary tumors of facial nerve are rare, difficult to diagnose due to their subtle and variable clinical manifestations and these are usually misdiagnosed as idiopathic facial nerve paralysis. A case of facial nerve sehwannoma in internal auditory meatus presenting as a tumor indistinguishable from acoustic neuroma clinically is presented here. Difficalties in patient assessment, inadequacy of diagnostic techniques presently available and surgical technique of the removal of the tumor will be discussed.     

Intraoperative monitoring of the facial nerve

Anatomic preservation of the facial nerve, with maximal facial function, is one of the goals of acoustic neuroma surgery. Application of electrophysiologic monitoring techniques is useful in achieving this goal. Preoperative electromyography and nerve conduction studies provide important prognostic information for preservation of the nerve and postoperative function. Intraoperative electromyography alerts the surgeon to facial nerve proximity and potential injury. Direct nerve stimulation is utilized to confirm the location and integrity of the nerve. Matched-pair analysis of two groups of patients demonstrated an increased ability to preserve the facial nerve with less postoperative facial deformity.     

Electrophysiologic evaluation of the facial nerve in patients with acoustic neuromas. Preliminary results of a comparative study between conventional electroneurography and transcranial magnetic pulse stimulation]

Subclinical invasion of the facial nerve by acoustic neuromas may be identified preoperatively using conventional electroneurography (ENOG). The clinical application of extratemporal stimulation distal to the stylomastoid foramen is limited in these cases because of the more proximal site of the lesion. Transcranial magnetic coil stimulation (MCS) is a non-invasive means by which the facial nerve is stimulated at the level of the motor cortex or the brain stem before it enters the internal auditory canal. Topographically such an assessment may have more diagnostic relevance than other forms of electrical stimulation in acoustic neuroma patients. To test this theory the facial nerves of 20 patients with an acoustic neuroma were stimulated using ENOG and MCS before and 1 week after operation. Stimulation parameters were comparable and included threshold, double-threshold and supra-threshold levels of stimulation while compound action potential amplitudes and early and late response latencies were monitored. All the patients had clinically normal facial nerve function preoperatively. Using ENOG 65% of the patients showed amplitude reduction on the tumour side, whereas 70% of these patients had a reduction of amplitude to MCS. Combining both techniques, 88% of the patients had a significant amplitude reduction on the neuroma side. Comparison of the preoperative threshold measurements of both techniques showed that there was a significantly higher incidence of detection of lesions on the diseased side in neuromas larger than 2 cm by the use of MCS.     

Surgical exposure of the facial nerve indications and techniques.

Lesions producing facial nerve palsy may occur within the temporal bone anywhere between the internal auditory canal and the stylomastoid foramen. Surgical exposure of this nerve may be necessary for decompression, grafting, rerouting, or removal of such lesions as acoustic tumour, meningioma, facial nerve neuroma, and cholesteatoma. Contemporary surgical exposure of the facial nerve has as its aim adequate exposure of the facial nerve at any point in its course, with preservation of hearing and vestibular function, without further injury to the facial nerve and the necessity for producing a mastoid cavity. When hearing and balance function are present, the transcanal-transtympanic approach to the horizontal segment of the facial nerve offers limited access to the facial nerve in its tympanic course. Wider exposure is obtained by postauricular transmastoid exposure of the tympanic and mastoid portions of the facial nerve. The middle fossa approach to the facial nerve offers access to the internal auditory canal and labyrinthine portions of the nerve, whereas the retrolabyrinthine approach offers access to the facial nerve in the posterior fossa. Total facial nerve exposure with preservation of hearing and balance function is obtained by the combined transmastoid and middle cranial fossa approach. In individuals who have lost all function of hearing and balance, the postauricular translabyrinthine approach offers total exposure of the facial nerve within the temporal bone and posterior fossa. The aim of this discussion was to present in succinct fashion a systematized approach to surgical exposure of the facial nerve within the temporal bone and posterior fossa.