大型听神经瘤的显微手术治疗及面神经保护探讨

目的：总结经枕下乙状窦后入路显微外科手术切除听神经瘤及面神经保护的经验和技巧,以提高肿瘤的全切率和面神经的保留率。方法31例听神经瘤患者采用经枕下乙状窦后入路显微手术治疗,术中均行面神经电生理监测及面神经保护。结果肿瘤全切29例（93．6％）,大部分切除2例（6．4％）。术中面神经解剖保留28例（90．3％）,面神经功能状态 H-B 分级：Ⅰ～Ⅱ级22例（70．9％）,Ⅲ～Ⅳ级7例（22．6％）,Ⅴ～Ⅵ级2例（6．5％）。无长期昏迷及死亡病例。结论娴熟的显微操作技巧和术中面神经电生理监测有助于提高肿瘤切除率及保护面神经。     

Long-term facial nerve function evaluation following surgery for large acoustic neuromas via retrosigmoid transmeatal approach

Purpose  

By evaluating the postoperative facial nerve function of large acoustic neuromas, the purpose of this study was to analyze the factors that influence the facial nerve function outcome and to explore the surgical strategy for large acoustic neuromas.     

Facial paralysis: traumatic neuromas vs. facial nerve neoplasms

Traumatic neuromas (TN) are benign proliferations of neural tissue that may occur without disruption of the facial nerve. The clinical presentation, as well as the radiographic appearance, may suggest neoplastic involvement of the facial nerve. Histologically, they may closely resemble neurilemomas (Schwannomas) or neurofibromas. Three cases of TN of the facial nerve associated with facial paralysis are presented here. Unlike previously reported cases, these tumors were not associated with chronic inflammatory middle ear disease. TN must be considered in the differential diagnosis and treatment of facial paralysis.     

听神经瘤显微手术治疗和面听神经功能保护的探讨

目的探讨听神经瘤显做于术治疗和面听神经功能保护的疗效。方法分析1999年10月至2002年10月收治经枕下乙状窦后内听道入路手术切除30例听神经瘤的资料，全部病例采用保留面听神经功能的显做外科技术。结果听神经瘤手术全切除29例（96．7％），次全切除1例；面神经解剖保留25例（83．3％），手术后12周面神经功能保留21例（70％）；耳蜗神经解剖保留25例83．3％），手术后2周有效听力保留2例（占术前存在有效听力患者的28．6％），有效听力丧失但可测听力保留15例。结论枕下乙状窦后经内听道入路的听神经显微手术，能够取得较好的肿瘤全切除率和面听神经功能保留率.     

显微外科手术治疗听神经瘤的价值

目的 评价听神经瘤显微外科手术切除术的临床价值。 方法 由枕下-乙状窦后入路施行显微手术切除的听神经瘤63例。采用先囊内后包膜的分块切除方法,磨开内耳道,切除内耳道内肿瘤。术中应用电生理监测定位面神经。 结果 肿瘤全切除52例,次全切除l1例。面神经解剖保留58例,前庭蜗神经保留29例。63例中获得随访58例,平均随访7.2年,复发2例,无手术死亡病例,远期面神经效果：Ⅰ级23例,Ⅱ级29例,Ⅲ级5例,Ⅳ级l例。听力好转9例,同术前8例。 结论 显微外科手术是治疗听神经瘤的主要治疗手段,在控制肿瘤和保留面、听神经功能方面可以取得满意的效果。     

The transcranial translabyrinthine approach to acoustic neuromas

We originally described the transcranial translabyrinthine approach (TCTL) to acoustic neuroma. The approach is a labyrinthine dissection that is performed via the suboccipital exposure. It allows a complete and direct visualization of the internal auditory canal and the identification of the facial nerve at "Bill's bar." The TCTL enhances the suboccipital approach and adapts to its concepts of the classical transmastoid translabyrinthine approach. We hereby report our initial experience with the TCTL and present the surgical results in six additional cases. We also discuss the indications of this approach and compare it to alternative approaches that are used for the removal of large acoustic neuromas that extend laterally in the internal auditory canal.     

Surgical management of acoustic neuromas during the last five years. Part II: Results for facial and cochlear nerve function

Postoperative facial and cochlear nerve function in 83 consecutive patients with acoustic neuromas, who were undergoing their initial surgical procedure during 1980-1984, have been examined. The facial nerve was preserved in anatomic continuity in 71% of cases. Various nerve grafting procedures were used when the facial nerve was divided; the most common of these was a faciohypoglossal anastomosis, which was performed in 20 cases. The facial and cochlear nerves were anatomically preserved in 30.1% of all patients having their initial surgical procedure. Good speech discrimination was preserved in four patients, whereas more crude hearing was preserved in six other patients.     

听神经瘤显微手术面神经损伤的预防

目的总结与分析听神经瘤显微手术中预防面神经损伤的方法。方法经MRI和（或）CT检查确诊的大型听神经瘤（≥4．0cm）180例（72％）及中型听神经瘤（2．4～4．0cm）70例（28％）。均采用经患侧枕下乙状窦后入路保留面神经的显微手术。注意三大解剖关系：骨性解剖、蛛网膜解剖、神经与血管的解剖。肿瘤囊内减压后,确认面神经的起始位置、面神经与肿瘤的关系、面神经变形与扭曲、面神经分离的方法、面神经的断裂端-端吻合。随访6个月～1年。结果肿瘤全切除240例（96．0％）;次全切除10例（4．0％）,其中死亡1例（0．4％）。面神经功能评定：Ⅰ级214例（85．6％）;Ⅱ级25例（10．0％）;Ⅲ级5例（2．1％）;Ⅳ级5例（2．1％）。结论术中注意典型的解剖位置,正确的手术入路和显微手术技术可达到较高的肿瘤全切除率,提高面神经的功能保全率。     

大型听神经瘤术中面神经功能监测及其预后评估——110例临床研究

目的 探讨面神经功能监测的方法学、准确性、实用性以及术中监测和面神经预后的关系。实现解剖保留面神经,改善面神经的预后。方法 术中使用Viking-Ⅳ型多导术中监测仪,对110例听神经瘤自发和诱发面肌肌电图进行监测。结果自发肌电图结合单极恒压诱发肌电图可以准确定位面神经。肿瘤全切后在面神经出脑干端刺激时,若刺激量在lV(0．1ms)可诱发EMG,则术后两周面肌功能在H—B分级的I级。面神经解剖率为95．5％。结论 术中面神经监测可以精确判断面神经的位置,提高面神经的解剖和功能保留率。长期随访提示面神经功能恢复理想。     

Chemotherapy of bilateral acoustic neuromas

In patients with bilateral acoustic neuromas, it is not unusual for the tumors to be of unequal size. At the time of the first examination, the smaller tumor may have already destroyed the hearing, while the ear with residual hearing may harbor a large acoustic neuroma. The remaining hearing is then at great risk if surgical removal of the tumor is attempted. Chemotherapy of bilateral acoustic neuromas is here presented as a possible alternative to surgery in those patients whose prognosis for conservation of hearing is poor.     

Postoperative MR findings in acoustic neuromas: nerve edema within the internal auditory canal

Postoperative MR findings of eleven acoustic neuromas were analyzed. MRI's were able to clearly visualize residual tumor around the 7th and 8th cranial nerves that were left to preserve cranial nerve function, although conventional X ray CT scans often failed to detect it due to artifacts in the parapetrous area. The facial nerves preserved during operations were also visualized from their brainstem portion to the internal auditory meatus. These findings indicate that MRI is excellent in delineating soft tissue in the CP angle that would be overlooked by conventional X ray CT scan. It was also found that the nerve bundles within the internal auditory canal gained increased signal intensity on the T1 and proton weighted images after surgical interventions and that this effect extended into the most distal end of the nerve bundles and even into the intracochlear portion of the cochlear nerve. The nerve bundles with increased signal intensity were conspicuously enhanced after intravenous administration of Gd-DTPA. This indicated that the blood nerve barrier of the nerves within the internal auditory canal were disrupted due to the surgical manipulations in excising tumors. Following such surgical manipulations, nerve edema ensued, although manipulations in the cerebello-pontine angle were done carefully and protectively under a surgical microscope. The clinical significance of disruption of the blood nerve barrier and following nerve edema were discussed from the standpoint of preservation of the 7th and 8th cranial nerve functions.     

The suboccipital approach to removal of acoustic neuromas

This article reviews the author's technique for removing acoustic neuromas by the suboccipital approach. Also discussed are various considerations regarding the selection and use of instruments for this operation. The anatomy of the internal acoustic meatus and the principles involved in facial- and cochlear-nerve preservation are described. A guide is provided for stepwise dissection of the internal acoustic meatus in the laboratory.     

显微手术切除大型听神经瘤

目的 探讨应用显微外科技术切除大型听神经瘤（直径≥３１ｍｍ）的治疗效果。方法 大型听神经瘤经ＣＴ或ＭＲＩ扫描检查确诊,应用显微率枕下－乙状窦后入路行肿瘤切除术２２８例,结果 全切除１８４例（８０．７％）,次全切除３３例（１４．５％）,部分切除１１例（４．８％）,术中面神经解剖保留率为８２．９％（１８９例）,术后死亡３例（１．３％）。长期随访观察２０１例（平均３．８年）,其中恢复良好者１８９例（９４     

Incidental discovery of acoustic neuromas

Our objective is to report 4 cases of incidentally discovered acoustic neuromas (ANs) and to determine the incidence of asymptomatic ANs. A prospective study of 161 consecutive patients undergoing gadolinium-enhanced MRI (Gd-MRI) at a tertiary-care university-affiliated medical center was carried out from September 1994 to April 1995. The Gd-MRI scans were performed for tentative diagnoses other than AN or sensorineural hearing loss. In 161 consecutive patients examined, no ANs were found incidentally on Gd-MRI scans. Previous studies have suggested that the incidence of occult ANs is as high as 1%. On the basis of our results, we suggest that the actual incidence may be lower. However, our study is limited by its small size and the low incidence of ANs in the general population. Also reported are the clinical and MRI characteristics of 4 patients with incidentally diagnosed ANs.     

Natural history of acoustic neuromas

The growth rate of acoustic neuromas was studied in a series of 50 patients who underwent follow-up imaging studies, since surgery was not performed after the initial diagnostic study or only performed after the follow-up studies. In 50% of the cases the tumor did not grow during the length of the follow-up. In the other patients the growth was less than 50% of the original tumor size in all but four. No correlation was observed between tumor growth, length of the follow-up, and age of the patient. Our results suggest a change in the management of this benign tumor.