Magnetic resonance imaging of acoustic neuromas: pitfalls and differential diagnosis

Summary A total of 162 patients with suspected acoustic neuromas underwent MR imaging at 1.5 T. All patients were injected with Gd DTPA or DOTA. In 72 patients, uni- or bilateral acoustic neuromas were detected. 18 cases were equivocal: In 9 cases, contrast enhancement was due to other tumors (5 meningiomas, 2 metastases, 1 hemangioma). In 1 case, misinterpretation resulted from partial volume effects with the petrous bone marrow. In one patient, previously operated on, increased signal was due to postoperative fat graft. Four hypersignals were due to intracanalicular venous or meningeal enhancement. Three cases are still equivocal. Most of the diagnostic problems may be obviated by precontrast MR imaging, multidimensional 3-mm sections, and fast imaging.     

带蒂骨骼肌桥接近端周围神经防治残端痛性神经瘤的实验与临床应用研究

目的：探讨神经瘤的形成机制和致痛机制及周围神经与带蒂骨骼肌桥接吻合后神经的生长情况。方法：Wistar大白鼠40只随机分为实验组与对照组，两组均将左侧坐骨神经在适当水平切断，远端神经切除，实验组近端神经分为2束，用带蒂骨骼肌桥接2个神经断端，对照组近端神经置于原位。饲养16周进行组织学检测。临床应用此方法治疗残端痛性神经瘤24例。结果：实验组再生的神经纤维顺利通过吻合口长入骨骼肌桥内，并在肌桥的肌束内生长，分布于肌纤维之间，未见有神经瘤形成。对照组均有典型的神经瘤形成。临床24例病人总计36个神经瘤，随访6～20个月按中日联谊医院评定标准优良率为92％。结论：带蒂骨骼肌桥接近端周围神经是防治残端痛性神经瘤的一种简单、实用、有效的方法。     

听神经瘤涉及的面神经段显微解剖学研究

目的探讨听神经瘤涉及的面神经段的显微解剖，为听神经瘤手术提供解剖学数据。方法利用福尔马林充分同定的15例成人尸头标本，对面神经的脑干端、桥小脑角段、内耳道段及其毗邻结构进行测量和拍照。结果面神经脑干端与周围解剖结构有恒定距离。桥小脑角段由面神经运动根、中间神经两个根组成，与前庭蜗神经走行关系恒定。内耳道段处面神经运动根在前庭蜗神经前上方，中间神经和面神经运动根在内耳道中部合成一干，近内耳道底处面神经在内耳道底的横嵴上．垂直嵴前走行。结论研究听神经瘤涉及的面神经段显微解剖，有助于听神经瘤的切除．保护面神经。     

经迷路－小脑幕入路切除大型听神经瘤

作者采用经迷路－内听道－小脑幕联合入路切除３０例大型听神经瘤。肿瘤全切除率达９６．７％，无手术死亡。面神经解剖保留率为５３．３％，功能保留率为３６．７％。该入路的主要优点是：（１）进路直接，显露良好；（２）充分打开内听道；（３）手术后反应轻；（４）入路可灵活变通或改良。对于手术技术、手术后并发症的防治和面神经保留等进行简要讨论。     

听神经瘤术中面神经电生理监测的问题与对策

Objective To explore the solutions to some problems of intraoperative facial nerve monitoring during operation for acoustic neuroma and evaluate the function of anatomically preserved facial nerve. Methods The tumors were resected with suboccipital retrosigmoid approaches under microscope in 25 cases. Intraoperative monitoring was used to protect facial nerve and evaluated its function. Results Total removal was achieved in 25 patients( 100% ). The facial nerve was preserved anatomically in 23 cases(92% ),H - B Grade Ⅰ～Ⅱ in 19 cases, Grade Ⅲ～Ⅳ in 5, Grade Ⅴ～Ⅵ in 1. Stimulative intensity at the end of tumor resection was related to the function of facial nerve, and the lower was the better. The function of facial nerve might be Ⅰ～Ⅱ grade when stimulative intensity was lower than 0. 5 mA, and facial electromyograph response amplitudes was greater than 100 μV. The function of facial nerve was not ideal when stimilative intensity was above 2 mA and response amplitude was not clear. Conclusions Skilled technique of intraoperative facial nerve electrophysiologic monitoring can obviously increase the rate of anatomical and functional preservation of facial nerve, and quantitative analysis of electromyogram may help to evaluate its postoperative function.     

MRI in acoustic neuroma: a review of 35 patients

Summary This retrospective study is aimed to assess the diagnostic efficacy of MRI in relation to contrast enhanced CT and air-CT-cisternography. MRI examinations were performed in 35 patients with suspected neurosensorial damage and suggestive of acoustic neuroma: 27 presented on MRI with unilateral tumors, 3 patients had a bilateral tumor and 5 patients were negative on all imaging modalities. The total number of acoustic neuromas detected was therefore 33. To date microscopic analysis has been performed on 12 tumors and histological data based on type Antoni A and Antoni B classification is available. Contrast enhanced CT detected 19 tumors, yielding an overall sensitivity rate of 58%. Air-CT cisternography identified an additional 5 tumors with a sensitivity rate of 100%. MRI identified 33 acoustic neuromas in 30 patients and was negative in 5 patients (sensitivity and accuracy 100%). Considering sensitivity in relation to location, MRI was much better than contrast enhanced CT for internal auditory canal (IAC) tumors (100% versus 36%) and better for cerebello-pontine angle tumors (CPA) tumors (100% versus 68%). The evolution of MRI technique, the various pulse sequences used and their actual selection is discussed. Seven patients received a paramagnetic contrast agent (Gadolinium-DTPA) with the additional benefit of a better demonstration of the tumor. The results suggest that MRI is the best non invasive technique for demonstrating acoustic neuromas.     

大型听神经瘤手术中面神经监测的效果观察

目的了解大型听神经瘤手术中连续面肌肌电图监测对术中、术后面神经解剖和功能保留的作用。方法根据Gormley颅内肿瘤分型方法,100例听神经瘤患者中肿瘤直径为4.0～4.9cm者82例,5.0～5.9cm者16例,直径≥6.0cm者2例。手术前采用House等面神经功能分级标准进行评估,Ⅰ级65例,Ⅱ级33例,Ⅲ级2例。采用经乙状窦后入路显微外科手术切除肿瘤,术中施行面肌肌电图监测和直接电刺激。结果100例中肿瘤全切除或近全切除者94例,大部分切除6例。2例肿瘤切除过程中切断面神经者均行Ⅰ期端-端吻合;2例面神经被切断1/2者行断端吻合。手术后2周面神经功能评估Ⅰ级30例,Ⅱ级50例,Ⅲ级10例,Ⅴ级10例;手术后1年随访面神经功能Ⅰ级76例,Ⅱ级14例,Ⅲ级7例,Ⅴ级3例。结论大型听神经瘤手术中采用面神经监测对面神经的解剖和功能保留有明显效果。     

阿霉素神经干注射联合神经瘤切除或松解治疗痛性神经瘤

目的 介绍一种治疗痛性神经瘤的新方法和初步临床疗效.方法 2002年～2006年,应用阿霉素神经干注射联合神经瘤切除或松解治疗痛性神经瘤患者9例.其中8例切除残端神经瘤后.将神经近端置于正常的软组织内;1例连续性神经瘤仅做神经松解.所有病例均在神经瘤切除或松解后,根据神经干粗细的不同分别用1%的阿霉素0.3～1.0 ml作近端神经干注射.结果 经过24～60个月的临床随访,7例残端神经瘤患者的疼痛明显缓解,1例疼痛减轻,1例无效(仅做神经松解),手术优良率为77.8%.结论 阿霉素神经干注射联合神经瘤切除能有效缓解残端神经痛.     

椎管内神经瘤的增强磁共振成像研究

目的：评估增强后磁共振成像诊断椎管内神经瘤的特异性。材料和方法：对经外科手术的２０例椎管内神经瘤患者，回顾性比较分析病理和ＭＲＩ（包括Ｔ１加权成像、Ｔ２加权成像和静脉注射Ｇｄ－ＤＴＰＡ后Ｔ１加权成像）。结果：在Ｔ１加权像，与脊髓相比，呈均质低信号９例，不均质低信号１０例，不均质高信号１例；在Ｔ２加权像，２０例均示明显高信号（均质１３例，不均质７例）；静脉注射Ｇｄ－ＤＴＰＡ后Ｔ１加权成像，２０例均示明显强化，据其强化形态不同分为①均质强化８例；②明显不均质强化５例，病理上存在坏死囊变和陈旧性出血；③“煤渣状”不均质强化７例，病理上可能由不同量的ＡｎｔｏｎｉＡ和ＡｎｔｏｎｉＢ组织交互存在所造成或部分代表显微镜下见的微囊改变。结论：Ｔ１加权像呈低信号，Ｔ２加权呈明显的高信号，注射造影剂后出现明显的不均质强化和“煤渣状”不均质强化，是椎管内神经瘤的特征性ＭＲＩ征象。     

听神经瘤术中面神经电生理监测的问题与对策

Objective To explore the solutions to some problems of intraoperative facial nerve monitoring during operation for acoustic neuroma and evaluate the function of anatomically preserved facial nerve. Methods The tumors were resected with suboccipital retrosigmoid approaches under microscope in 25 cases. Intraoperative monitoring was used to protect facial nerve and evaluated its function. Results Total removal was achieved in 25 patients( 100% ). The facial nerve was preserved anatomically in 23 cases(92% ),H - B Grade Ⅰ～Ⅱ in 19 cases, Grade Ⅲ～Ⅳ in 5, Grade Ⅴ～Ⅵ in 1. Stimulative intensity at the end of tumor resection was related to the function of facial nerve, and the lower was the better. The function of facial nerve might be Ⅰ～Ⅱ grade when stimulative intensity was lower than 0. 5 mA, and facial electromyograph response amplitudes was greater than 100 μV. The function of facial nerve was not ideal when stimilative intensity was above 2 mA and response amplitude was not clear. Conclusions Skilled technique of intraoperative facial nerve electrophysiologic monitoring can obviously increase the rate of anatomical and functional preservation of facial nerve, and quantitative analysis of electromyogram may help to evaluate its postoperative function.