听神经瘤手术的听力保护

探讨听神经瘤手术的听力保护.方法报告两例经乙状窦后进路、内镜辅助和术中用CAP和ABR连续适时监测下切除听神经瘤的结果.结果例1 MRI示内听道口外瘤体直径约1.5cm,术前语频纯音听阈平均在30dB,能引出ABR各波.术中以ABR适时监测,完全切除瘤体后仍可引出清楚的ABR Ⅰ、Ⅲ、Ⅴ波,术后无面瘫.术后7个月复诊,纯音听阚及ABR波间期恢复术前水平.例2为双侧听神经瘤.MRI示左右听神经瘤直径分别为4cm和5cm.一侧肿瘤切除后间隔4个月行另一侧听神经瘤切除术.为保留第二次手术耳听力,术中用CAP监测.术中虽未能保留蜗神经,但切除肿瘤后仍可记录到CAP.结论听神经瘤手术中的CAP监测结果无法评判术后能否保留听力,而ABR则能够及时反映听神经及其通路的功能状态,肿瘤切除后引出ABR Ⅰ、Ⅲ、Ⅴ波可有望保存术前听力.     

听神经瘤术中听力监测及术后听力保留影响因素分析

目的探讨听神经瘤术中听力监测的应用及术后听力保留的可能影响因素。方法16例采用乙状窦后入路手术切除听神经瘤的成年患者,分为两组,术中采用听性脑干反应(auditory brainstem response,ABR)和耳蜗电图(electrocochleogram,ECochG)联合监测为监测组(8例),未监测者为未监测组(8例),比较两组患者术后听力保留情况,采用单因素分析,分析影响听力保留的可能因素,包括:年龄、病程、肿瘤大小、术前纯音听阈和言语识别率、术中是否行ABR和ECochG联合监测、内听道是否扩大、肿瘤和神经是否粘连等。结果前庭诱发肌源性电位(VEMP)提示16例患者肿瘤来源于前庭上神经,监测组中6例术中及术毕ABR波Ⅰ、Ⅴ和复合动作电位(CAP)持续存在,术后听力保留;1例术中ABR波Ⅰ、Ⅴ和ECochG CAP持续存在,但术后无可用听力;1例术中切除肿瘤时ECochG与基线重复性良好,ABR波V消失,手术结束波V仍未恢复;监测组术后听力保留率为75.0%(6/8),未监测组术后无一例保留听力,差异有统计学意义(P=0.007)。单因素分析显示,年龄、病程、肿瘤大小、术前纯音听阈以及内听道扩大与术后听力保留率无关(P>0.05),术前言语识别率、术中ABR和ECochG联合监测、肿瘤和神经粘连与否与术后听力保留率相关(P<0.05)。结论听神经瘤切除术中ABR和ECochG连续监测对指导手术和提高术后听力保留率有重要意义,肿瘤与神经粘连是术后听力保留的重要影响因素,手术技巧、术前听力、肿瘤大小、内听道扩大等是否是术后听力保留的影响因素需扩大样本进一步研究验证。     

听神经瘤切除术后耳蜗电图的异常改变

耳蜗电图（ECochG）与听性脑干诱发电位（ABR）的结合已被广泛应用在桥小脑角肿瘤术中的听功能监测。手术中听神经机械损伤会立即在ABR中表现为阈值升高，振幅下降和潜伏期延长或出现复合动作电位（CAP）的消失。然而术中ECochG表现并不总能预测术后听力学情况。该文报告一例听神经瘤患者的术前，术中和术后ECochG表现并讨论术后ECochG波形的异常改变。病例为女性43岁。因双耳鸣，伴左耳听力下降加重半年就诊。既往有较严重眩晕病史。首次纯音测听检查听阈IkHZ为65dB，ZkHZ为60dB，言语分辨率7O％，ZkHZ和4kHzBekesy听力曲线…     

两种听觉监护在听神经瘤术中的联合应用及评价

目的　探讨听神经瘤手术中听觉监护的意义。比较听性脑干反应（ABR）和蜗神经动作电位（cochlear nerve action potential,CNAP）在听觉监护应用中的价值。方法　回顾性分析我中心12例保留听力手术的听神经瘤患者资料及术中情况,患者术前均有实用听力（AAO-HNS分级A级、B级）,可引出ABR波形,V波分化可,所有手术均采取乙状窦后径路摘除肿瘤。所有患者均全程ABR监护,术中打开脑膜后联合监测CNAP。结果　手术过程中所有患者ABR波形较术前基线均有不同程度的变化,可记录到V波潜伏期均较基线延长（0.68±0.41）ms。CNAP波幅个体差异性较大,可记录到的P1潜伏期均较基线延长（0.25±0.16）ms。12例中有8例（66.7%）患者术后保留可用听力;另外4例（33.3%）术后达不到可用听力,此4例患者ABR表现为3例V波消失,1例V波潜伏期延长。CNAP表现为2例CNAP的P1消失,2例P1延长。电钻钻磨造成的震动和噪声、手术时神经被牵拉或热损伤后等急性损伤后ABR和CNAP波幅均出现短时间急剧下降,手术暂停5 min后,部分患者波幅可在一定程度恢复。结论　听神经瘤手术中ABR和CNAP对于听觉监护均有一定意义。ABR波形稳定可靠,但叠加时间相对较长;CNAP叠加快速,可提升监测灵敏度,但波形变异度较大。电钻钻磨造成的震动和噪声、操作过程中对神经组织的牵拉以及热损伤均被及时监控,两者联合应用可提升听神经瘤手术的听觉功能保留率。     

耳蜗性听力损失对ABR参数的影响

为了解耳蜗听力损失对ABR诸参数的影响，本文通过对40例（48耳）的平坦型、高频型、切迹型听力损失三组不同听力曲线图的耳蜗性听力损失，其ABR诸参数与正常对照组比较分析，得出高频型听力损失组Ⅰ、Ⅲ、Ⅴ各波潜伏期均较正常对照组明显延长，波间间期无明显差异；切迹型听力损失组V波及Ⅰ-Ⅴ波间期轻度延迟，但无显著意义；平坦型听力损失组与正常对照组无显著差异。实验结果提示：耳蜗性听力损失的类型对ABR诸参数有一定影响，因此，临床上应用ABR诊断蜗后病变时需考虑这些因素的存在。     

听性稳态诱发反应在听力异常婴儿的诊断意义

目的听性稳态诱发反应（auditory steady—statere sponse，ASSR）新技术与视觉强化测听（vision reinforcement audiometry，VRA）阈值的相关性分析研究，探讨听神经病症侯群及其鉴别诊断。方法10例（20耳）对照组，年龄6～12个月，测得ASSR和VRA的正常阈值。16例（26耳）异常听力组患儿（年龄在3～6个月），根据其所患疾病分为3个亚组：Ⅰ组为早孕感染组5例（8耳），Ⅱ组为窒息缺氧组5例（10耳），Ⅲ组为高胆红素血症组6例（8耳），检测畸变产物耳声发射（DPOAE）、听性脑干反应（ABR）潜伏期、肌反射值与ASSR和VRA及其相关性结果对照。结果Ⅰ组中2例次（2耳次）为单纯疱疹病毒感染。5例次（8耳次）DPOAE消失，4例次（6耳次）ABR波Ⅰ潜伏期延长、Ⅰ—Ⅴ波间潜伏期缩短，3例次（6耳次）500Hz和1000Hz的镫骨肌反射正常，2例次（2耳次）镫骨肌反射阈偏高，初步推测单纯耳蜗性病变，排除听神经病可能，测得ASSR平均估计阈值与VRA平均阈值具有很好的相关性（r=0．95～0．98）。Ⅱ组中4例次（8耳次）畸变产物耳声发射消失，其中1例次（2耳次）ABR波Ⅰ、波Ⅲ、波Ⅴ消失和肌反射消失，3例次（5耳次）ABR波Ⅰ消失和波Ⅲ及波Ⅴ潜伏期延长，以及肌反射消失。2例次（3耳次）Ⅰ-Ⅲ波间潜伏期延长，肌反射也消失。推测可能为听神经病症侯群（耳蜗至脑干下听觉传导通路受损）伴有耳蜗功能障碍，测得ASSR平均估计阈值与VRA平均阈值具有较好的相关性（r=0．72～0．84）。Ⅲ组中6例次（8耳次）DPOAE存在，4例次（5耳次）ABR波Ⅰ、Ⅲ、Ⅴ和肌反射消失，2例次（3耳次）Ⅰ—Ⅴ波间潜伏期延长，镫骨肌反射阈正常偏高，初步分析推测为听神经病症侯群病损在脑干以上，测得ASSR平均估计阈值与VRA平均阈值具有很弱的相关性（r=0．43～0．64），ASSR阈值和VRA阈值不一致，进一步说明这组的病损应该在脑干或皮层。3个亚组的每个频率（0．25、0．5、1、2,4kHz）平均ASSR和VRA阈值差值比较，差异都具有统计学意义（F检验，P〈0．05、P〈0．01、P〈0．01、P〈0．05、P〈0．05）。结论通过ASSR阈值和VRA阈值相关性技术研究或许可提供诊断及鉴别诊断在各种频率听力障碍婴儿的听神经病症侯群（病变高位）、听神经病症侯群伴有耳蜗功能障碍（病变低位）以及单纯耳蜗性病（非听神经病）。     

急性高胆红素血症豚鼠听功能研究

目的 探讨急性高胆红素血症对听功能的影响及病损部位。方法建立急性高胆红素血症豚鼠模型，检测其听性脑干反应（ABR）、听神经复合动作电位（CAP）阈值及潜伏期、耳蜗微音器电位（CM）、畸变产物耳声发射（DPOAE）。结果实验组动物出现ABR反应阈升高，伴波Ⅰ、Ⅲ、Ⅳ潜伏期及Ⅰ-Ⅲ、Ⅲ-Ⅳ波间期明显延长，与对照组比较有显著差异（P〈0．01）；CAPN1、N2波潜伏期延长，与对照组比较有显著差异（P〈0．01）；实验组有2只动物（3耳）ABR、CAP未引出；CM在8、4、1kHz处幅值下降，DPOAE各频率幅值下降；电镜示螺旋神经节细胞胞浆空泡状改变、包绕髓鞘板层松解。结论高胆红素血症不但引起中枢听觉传导通路的损害，亦可累及耳蜗，其耳蜗毒性机制尚需进一步探讨。     

听神经瘤手术的听力保存技术

目的 探索听神经瘤切除术中保留术前残余听力的可能性,以及评价术中动态听力监测和耳内镜技术对听力保护的效果.方法 2003年至2007年7月共收治听神经瘤手术患者138例,对术前有残余听力18例(18耳)施行术中连续听力监测.男6例,女12例;左12耳,右6耳;年龄14～64岁;15例为单发的听神经鞘瘤,3例为神经纤维瘤病Ⅱ型.MRI测得肿瘤最大直径在12～33 min,中位数19.5 min.均采用经乙状窦后入路,10耳辅以耳内镜下手术.18例均行听性脑干反应(ABR)及耳蜗电图术中连续听力监测;术中常规监测面神经功能.术后随访时间为6个月～2.5年,以最后一次听力结果为准.术前及术后听力评价标准采用1995年美国耳鼻咽喉头颈外科学会分级法.结果 手术全切16例,大部分切除2例(均为神经纤维瘤病Ⅱ型).无死亡病例,术后均恢复顺利,无脑脊液漏,无皮下血肿等术后并发症.18例术前均无面神经麻痹,术中面神经均得以保存,解剖结构连续完整.术后7 d面神经功能Ⅰ～Ⅱ级占50.0%(9/18);术后6个月面神经功能Ⅰ～Ⅱ级占88.9%(16/18).18耳中11耳术后听力得以保存(61.1%),术后听力A级4耳,B级4耳,C级2耳,D级1耳.术前肿瘤>20 min者共5耳仅2耳保存听力,<20 mm者共13耳术后听力保存9耳(69.2%).耳内镜辅助下手术10耳,听力保存8耳(80.0%).术中监测发现,手术过程中当磨钻内耳道后唇、内耳道口附近处牵拉或电凝止血,尤其是夹持内听动脉、处理内耳道处肿瘤及夹持或电凝肿瘤表面最内层蛛网膜血管时,对ABR和耳蜗电图波形影响很大.结论 对术前有良好听力的听神经瘤患者应在术中辅以实时动态听力监测,并结合术中耳内镜技术进行听力保护,术后能够获得较好的听力保存效果.听神经瘤表面蛛网膜的保留及其血供状况对保留听力起重要作用,而内听动脉的损伤是术后听觉丧失的最主要原因.     

桥小脑角占位性病变的临床听力学表现

本文总结了经CT或MRI证实以及部分经手术证实的101例桥小脑角占位性病变的纯音测听，听性脑干反应（ABR），耳蜗电图（ECochG）以及前庭功能的表现。结果显示：ABR多表现为Ⅰ～Ⅴ间或延长（＞45ms），仅Ⅰ波存在或ABR各波均消失。未见波Ⅴ幅度小于波Ⅰ。当肿物较大时，可见时测ABR异常。极重度聋患者（35．5％），仍可引出异常ABR波形，故仍不可忽视ABR检查；听力轻度下降，甚至正常考ABR仍有改变。AP出现率随肿物增大而降低，－SP／AP比值≥0．4，可能是继发性伤及耳蜗所致。5例ABR表现正常者仍有半规管功能低下。提示前庭功能检查对桥小脑均占位性病变的诊断具有一定参考意义，临床应将ECochG和前庭功能检测列为诊断桥小脑角占位性病变的参考指标。     

听神经瘤致聋机理—14例（16耳）听神经瘤病人听力测试结果分析

目的：探讨听神经瘤听力损失的病理生理机制。方法：对14例（16耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（ABR）、诱发耳声发射测试（EOAE）及CT和（或）MRI扫描。EOAE能引出的4耳还检测其传出抑制功能，ABR不能检测且EOAE不能引出的重度聋（听力损失大于80dB)有5耳行鼓岬刺激试验（PST）。结果：16耳听神经瘤中2耳（12．50％）听力损失源于神经性损害；6耳（37．50％）蜗性损害；8耳（50％）蜗－神经性损害。能引出EOAE的4耳均有传出功能障碍。结论：EOAE可评价听神经瘤的耳蜗功能形态；ABR结合PST能分析听神经瘤的蜗后神经功能。听神经瘤的听觉病理可同时或单独发生于听外周的耳蜗水平、第Ⅷ对颅神经（传入神经）水平和橄榄核耳蜗传出神经水平。     

Hearing Preservation in Acoustic Neuroma Surgery

Introduction An acoustic neuroma (AN) is a neurinoma arisingfrom the vestibular branch of the VIIIth cranial nerve,thereby also termed “vestibular schawnnomas (VS)”.The histo-pathologically benign nature of this tumorgives the possibility for neuro-otologists to preserve thecochlear nerve and hearing in tumor resection sur-geries. Advances in imaging technology have greatlyimproved early diagnosis of ANs with very small sizesand made tumor removal without significantly insultinghearing. …     

Hearing preservation using combined monitoring of extra-tympanic electrocochleography and auditory brainstem responses during acoustic neuroma surgery

The aim of this study was to evaluate the efficacy of an intraoperative monitoring hearing preservation strategy that includes simultaneous recordings of an auditory brainstem response (ABR) and non-invasive electrocochleography (ECochG). The combined ABR and tympanic membrane (TM) ECochG testing was performed in 74 patients undergoing acoustic neuroma (AN) surgery. In addition, EMG recordings were conducted to monitor the facial nerve function. Hearing was preserved in 19 of the 30 patients with residual hearing prior to surgery (63%), and facial nerve function was maintained in 89% of the patients. In most cases, the presence of both auditory brainstem and TM-ECochG responses at the end of surgery was associated with preservation of postoperative functional hearing; however, eight patients had a TM-ECochG response with a complete loss of the ABR, pointing to deafferentation of the auditory nerve. Tumour size and preoperative hearing thresholds significantly affected the postoperative hearing. The TM-ECochG response yielded large reproducible responses, which, in some patients, was the only way to monitor the auditory function. This auditory monitoring approach offers a valuable auditory tool that helps to improve the hearing preservation during AN surgery.     

Hearing preservation using combined monitoring of extra-tympanic electrocochleography and auditory brainstem responses during acoustic neuroma surgery

The aim of this study was to evaluate the efficacy of an intraoperative monitoring hearing preservation strategy that includes simultaneous recordings of an auditory brainstem response (ABR) and non-invasive electrocochleography (ECochG). The combined ABR and tympanic membrane (TM) ECochG testing was performed in 74 patients undergoing acoustic neuroma (AN) surgery. In addition, EMG recordings were conducted to monitor the facial nerve function. Hearing was preserved in 19 of the 30 patients with residual hearing prior to surgery (63%), and facial nerve function was maintained in 89% of the patients. In most cases, the presence of both auditory brainstem and TM-ECochG responses at the end of surgery was associated with preservation of postoperative functional hearing; however, eight patients had a TM-ECochG response with a complete loss of the ABR, pointing to deafferentation of the auditory nerve. Tumour size and preoperative hearing thresholds significantly affected the postoperative hearing. The TM-ECochG response yielded large reproducible responses, which, in some patients, was the only way to monitor the auditory function. This auditory monitoring approach offers a valuable auditory tool that helps to improve the hearing preservation during AN surgery.     

Tympanic ECochG and conventional ABR: a combined approach for the identification of wave I and the I-V interwave interval

Identification of wave I and measurement of the I-V interwave interval (IWI) are important parameters of the auditory brain stem response (ABR). However, at low stimulus sensation levels, wave I may be absent in the presence of wave V when the ABR is recorded conventionally with scalp electrodes. Several studies have shown that the amplitude and detectability of wave I (or N1) can be enhanced via extratympanic electrocochleography (ECochG), and even more so with tympanic ECochG. In the present study, tympanic ECochG was combined with conventional ABR to compare the amplitude and sensitivity of N1, wave I, and wave V in normally hearing subjects, and to identify the N1-V IWI in hearing impaired subjects whose conventional ABRs did not contain a reliable wave I. For the normally hearing subjects, the amplitude of the N1 was considerably larger than the amplitudes of waves I and V of the conventional ABR and there was no significant difference between N1 and wave V thresholds. For the hearing impaired group, the combined ECochG-ABR approach allowed for the identification of N1 and measurement of the N1-V IWI in all subjects. Our results support the use of tympanic ECochG in combination with conventional ABR for certain audiological and neurological applications.     

小儿蜗后听觉神经损害的临床与听力学特征及定位

目的 探讨包含了听神经病在内的ABR严重异常、DPOAE正常为特征的蜗后听觉神经功能障碍小儿的临床与听力学特征及其可能的病损部位.方法 选取2002至2006年听力专科中ABR严重异常、DPOAE正常,排除中耳传导功能异常的患儿86例(165耳),年龄8 d～7岁,平均1岁1个月,入选为本研究对象.选择ABR严重异常、DPOAE异常、排除中耳病变的听功能障碍26例(29耳)患儿作为蜗性病变对照组,选择健康同龄儿童86例(166耳)作为正常对照组,比较蜗后病变、蜗性病变、正常听力3组间ABR波Ⅰ、波Ⅲ、波Ⅴ潜伏期和振幅,以及Ⅰ～Ⅲ波间期等参数的异同.所有数据采用SPSS11.0统计软件包进行t检验.结果 86例蜗后听神经损害患儿中,51例(59.3%)的病例新生儿期有高胆红素血症史,其中40例血中间接胆红素水平达重度标准,11例为轻中度;在首次就诊的原因中,主诉运动障碍者40例(46.5%),听力言语障碍者10例(11.6%);在伴随的疾病中,32例(37.2%)确诊伴随有脑性瘫痪.在86例165耳蜗后听觉神经功能障碍患耳中,103耳最大强度声刺激(103 dB)ABR无波分化,27耳仅见波Ⅰ分化,19耳仅见波Ⅴ分化,13耳见波Ⅰ+Ⅲ分化,3耳见波Ⅰ+Ⅴ分化.仅见波Ⅰ分化耳,其波Ⅰ潜伏期较正常听力耳延长,振幅较正常听力耳低矮(t值分别为-6.75和2.58,P值均<0.05);有波Ⅰ+Ⅲ分化耳,波Ⅰ潜伏期和振幅与正常听力耳差异无统计学意义,波Ⅲ潜伏期则较正常听力耳延长,振幅较正常听力耳低矮(t值分别为-2.77和3.63,P值均<0.05),Ⅰ～Ⅲ波间期较正常听力耳Ⅰ～Ⅲ波间期延长(t=-2.99,P<0.05).结论 在蜗后听觉神经功能损害类型中,最常见的类型为ABR从波Ⅰ开始就严重异常,即听神经病,其病变主要在第Ⅷ颅神经听支;仅见波Ⅰ分化耳,其病变部位主要在第Ⅷ颅神经听支以后;ABR有波Ⅰ+波Ⅲ分化耳,主要病变部位在波Ⅲ的发源神经核团,即上橄榄核以后的听觉神经通路.振幅低矮的波Ⅴ不是听神经病独有的特征.高胆红素血症导致的蜗后听觉神经系统病变的病例中,其受侵害部位的先后次序可能为大脑皮层、腩干听觉神经核团、第Ⅷ对颅神经听支.     

Acoustic neuroma surgery: absent auditory brainstem response does not contraindicate attempted hearing preservation.

OBJECTIVE: Absence of auditory brainstem response (ABR) waveforms has been associated with a poor likelihood of hearing preservation following resection of acoustic neuromas. Our experience is reviewed for patients with absent preoperative ABR regarding hearing preservation, hearing improvement, and return of ABR. STUDY DESIGN: Retrospective review of 22 cases of acoustic neuroma resection. Nine patients with absent preoperative ABR were identified. All underwent tumor resection utilizing intraoperative cochlear nerve action potential (CNAP) monitoring. Postoperative hearing results and ABR waveforms were examined. METHODS: Charts were reviewed and tabulated for age, sex, tumor side, tumor size, preoperative and postoperative audiometric and ABR results, intraoperative monitoring results by ABR and CNAP, and surgical complications. RESULTS: Hearing preservation was achieved in seven of nine patients (78%) with absent preoperative ABR, as well as six of seven patients (86%) with tumors less than or equal to 20 mm in greatest dimension. Although intraoperative ABR monitoring was not possible in any of these patients, CNAP monitoring was successful in all. Return of ABR waveforms was observed in four of the six patients (67%) tested from 3 to 22 months postoperatively. Four of the seven patients (57%) enjoyed improvement in hearing class as defined by the guidelines of the American Academy of Otolaryngology-Head and Neck Surgery. CONCLUSIONS: Absent ABR waveforms have not been a negative prognostic sign regarding hearing preservation. CNAP monitoring is possible in these patients and likely helps to minimize iatrogenic cochlear nerve trauma. Patients with no ABR waveforms have hope of hearing preservation and even improvement following acoustic neuroma resection performed utilizing CNAP monitoring and hearing preservation surgical techniques.