听性脑干反应和蜗神经直接动作电位联合听觉监护在侧颅底手术中的应用

目的:通过听性脑干反应(ABR)和蜗神经动作电位(CNAP)在侧颅底外科手术中的应用,分析造成听力损伤的原因,并对这两种听觉监测技术作出评价。方法:在手术过程中对14例保留听力的侧颅底手术的患者进行听觉监测。ABR在整个手术过程中监测,CNAP在打开脑膜、暴露蜗神经后进行监测。在患者出院后1个月左右随访听力。结果:所有患者在手术过程中都有不同程度的ABR变化,尤其是耳科电钻使用后[相对使用前延长(0.19±0.16)ms)]和颅内操作时[相对操作前延长(0.29±0.25)ms]。部分患者的波形潜伏期延长在术毕时有所恢复[10例,平均缩短(0.27±0.16)ms]。结论:侧颅底手术中应用听觉监护能防止听觉损伤。电钻使用造成的震动和噪声对听力有损伤,解除引起波形潜伏期延长的诱因后可恢复部分听力。术后的听力预后与术毕潜伏期的延长有相对应关系。术中监测的新趋势是联合应用ABR和CNAP,取长补短。     

听觉脑干诱发电位波形变化在听神经瘤诊断中的意义

目的探讨听神经瘤病人听觉脑干诱发电位(ABR)波形改变的意义。方法对手术证实为听神经瘤的23例病人ABR的潜伏期、波形进行回顾性分析。结果在23例病人中,11例潜伏期延长,Ⅰ~Ⅴ波间期耳间差(IPL)大于0.4 ms;2例潜伏期延长,但Ⅰ~Ⅴ波间期耳间差小于0.4 ms;2例V波缺失;8例无波形反应。全部患侧波形均异常、重复性差,2例出现对侧波形异常。结论ABR波形变化在听神经瘤诊断中有重大意义;波形异常、重复性差可作为判断ABR异常的辅助指标。     

听神经瘤手术的听力保存

目的探讨听神经瘤手术的听力保留。方法回顾分析2000年至2012年在解放军总医院耳鼻喉头颈外科经听力保留手术切除听神经瘤的病例。结果 32例患者中,术后成功保留听力者为43.8%(14/32)。其中,听功能A级者5例,B级者5例,C级者3例,D级者1例。结论保留听力的听神经瘤切除术可取得相当的听力保存率,是可选择的听神经瘤治疗方法。     

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.     

听神经瘤引起突发性听力减退

为了避免听神经瘤的误诊误治，对１９８６～１９９５年收治听神经瘤１０４例中２３例（２４耳）首发症状表现为突发性听力减退者（占２３％）的病例进行分析。听力学检测：纯音听阈＞７１ｄＢＨＬ者１３耳，占５４．２％；听性脑干反应（ＡＢＲ）检测均有异常；耳蜗电图－ＳＰ／ＡＰ检测９耳中７耳＞０．４，占７７．８％；声反射检测１１耳均消失。眼震电图检测１８例，１７例异常（占９４．４％）。影像学检查ＣＴ阳性率８８．８％，阴性者行ＣＴ气脑造影或磁共振（ＭＲＩ）检查均能确诊。提示对突发性听力减退患者应常规检查ＡＢＲ，若异常应行颞骨ＣＴ，必要时ＭＲＩ影像学检查。     

听神经瘤的耳声发射观察

目的 观察和分析听神经瘤的耳声发射特点,为评估听神经瘤患者的耳蜗功能和选择保护听力的术式提供参考依据.方法 对20例（22耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（auditory brainstem response,ABR）、诱发性耳声发射（evoked otoacoustic emissions,EOAE）测试及CT和（或）MRI扫描,能引出EOAE的瘤耳检测其自发性耳声发射（spontaneous otoacoustic emissions,SOAE）和传出抑制功能.结果 28.57%听神经瘤耳能引出EOAE,按其畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）特点分为三型：①“耳蜗型”3耳;②“非耳蜗型”2耳;③“混合型”1耳;“非耳蜗型”耳能引出强大的SOAE;能引出EOAE的6耳均有内侧橄榄耳蜗传出系统功能障碍.结论 EOAE可精确分析听神经瘤患者的耳蜗（外毛细胞）功能,部分听神经瘤病人存在“离断耳”现象.耳声发射（otoacousticemissions,OAE）在诊断重度感音神经性聋（包括听神经瘤病人）方面有一定潜能.     

听神经瘤临床听力学特征分析

目的　分析听神经瘤患者临床听力学特征,为听神经瘤的诊断提供参考依据。方法　回顾性分析首都医科大学附属北京天坛医院耳鼻咽喉头颈外科接诊的394例单侧听神经瘤患者临床资料,所有患者均行纯音测听、言语识别率、听性脑干诱发电位和颅脑增强MRI。结果　患侧听力正常者54例,轻度听力损失58例,中度63例,中重度45例,重度45例,极重度31例,全聋者98例;高频听力损失最多见。24.7%患者言语识别率和纯音测听下降不成比例。听性脑干诱发电位波形正常者8例,波形缺失者228例和其他波形异常者158例;听性脑干诱发电位诊断听神经瘤的敏感度：内听道内肿瘤85.7%,内听道外98.5%。结论　听神经瘤的听力学表型多样,听力正常者不能排除听神经瘤;听力损失程度不能预判肿瘤大小;纯音测听与言语识别率不一致应警惕蜗后病变;听性脑干诱发电位诊断听神经瘤敏感度随肿瘤增大而增加。     

大型听神经瘤肌电图监护与术后面神经功能的相关性研究

目的　研究面肌肌电图与大型听神经瘤术后面神经功能预后的关系 ,探讨可以预测术后面神经功能的面肌肌电图的定量指标。方法　对 32例大型听神经瘤在面肌肌电图监护下行显微手术切除 ,测定面神经脑干端与内听道端刺激阈值 ,计算其比值 ,并对比值与术后的面神经功能进行相关分析。结果　 2 9例于面神经的脑干端和内听道端刺激后均引出动作电位 ,脑干端的刺激阈值为 (3.6 4± 5 .80 )mA(0 .5～ 31.5 0mA) ,内听道端刺激阈值为 (3.0 0± 5 .11)mA(0 .4～ 2 8.0 0mA) ,脑干端刺激阈值与内听道端刺激阈值的比值为 :1.2 4± 0 .16 (1.0 0～1.6 0 ) ;用Spearman相关分析表明 ,脑干端刺激阈值与内听道端刺激阈值与术后 1d、3d、1周、3个月、6个月和 1年的面神经功能无相关性 (P >0 .0 5 ) ,而脑干端刺激阈值与内听道端刺激阈值的比值与术后 6个月和 1年的面神经功能呈正相关 (r =0 .5 2 1,P =0 .0 18;r =0 .6 14 ,P =0 .0 0 4 )。结论　面肌EMG术中监护可以帮助术者早期辨认和确定大型听神经瘤面神经的走行方向 ,肿瘤切除后确认面神经结构是否完整 ,脑干端刺激阈值与内听道端刺激阈值的比值可以预测面神经功能的预后。     

听神经病患者80Hz听觉稳态诱发电位研究

目的:探讨听神经病患者80 Hz听觉稳态诱发电位的特点及与听性脑干诱发电位V波的相关性.方法:以1000 Hz短音95 dBnHL作声刺激,比较听神经病组和正常对照组80 Hz听觉稳态诱发电位及短音听性脑干反应(ABR)的波形差异.结果:听神经病组两种听觉诱发电位波形的同时引出率为85.4%且波幅低或极低,ABR的Ⅰ、Ⅲ波消失;14.6%两种听觉诱发电位波形同时消失.而正常对照组两种波形的同时引出率为100.0%.结论:80 Hz听觉稳态诱发电位与听性脑干反应的V波有明显相关性.     

以突发性听力减退为首发症状的听神经瘤临床特点分析

目的分析突发性听力减退为首发症状的听神经瘤的临床特点,以避免对该病的误诊、误治。方法对1983～1997年收治听神经瘤92例中20例（21耳）首发症状为突发性听力减退的病例（占21.7%）进行回顾性分析。结果听力学检测纯音听阈（500Hz、1000Hz、2000Hz听力平均听阈）＞71dBHL者12耳,占57.1%;听性脑干反应（auditorybrainstemresponse,ABR）检测均有异常;声反射检测9例（10耳）均消失。影像学检查CT阳性率为88.89%,阴性者行CT气脑造影或磁共振成像（magneticresonanceimaging,MRI）检查均能确诊。结论对突发性听力减退可疑听神经瘤的患者应常规检查ABR,出现异常者应进行颞骨CT,必要时行MRI检查。     

Evaluation of three intraoperative auditory monitoring techniques in acoustic neuroma surgery

OBJECTIVE: To assess the efficacy of three intraoperative auditory monitoring techniques: auditory brainstem response (ABR), electrocochleography (ECoG), and direct eight nerve monitoring (DENM). STUDY DESIGN: A retrospective review of the intraoperative recordings of ABR, ECoG, and DENM was performed. SETTING: A private, neurotologic practice. PATIENTS: Sixty-six patients with usable preoperative hearing underwent intraoperative auditory monitoring with ABR, ECoG, or DENM. INTERVENTIONS: Intraoperative auditory monitoring. MAIN OUTCOME MEASURES: Postoperative pure-tone hearing threshold and word recognition scores. RESULTS: Of the 66 patients, 16 (24%) had postoperative serviceable hearing. Five (18%) of the 28 with ABR monitoring, 3 (17%) of the 18 with ECoG monitoring, and 8 (40%) of the 20 with DENM monitoring had serviceable hearing after surgery. CONCLUSIONS: This study suggests that DENM may be more effective than ABR or ECoG, although the differences in hearing preservation rates are not statistically significant.     

听神经瘤术中连续听力监测的初步探讨

目的探讨听神经瘤外科术中连续听力监测的意义。方法采用乙状窦人路，在听性脑干反应（auditory brainstem response，ABR）和耳蜗电图（electrocochleogram，ECochG）监测下完成的听神经瘤切除术10例。对手术过程和术后听力结合术中监测进行分析。结果10例听神经瘤术前听力A级3耳，B级4耳，C级3耳（美国耳鼻咽喉头颈外科学会分级标准）。术前的ABR检查Ⅰ、Ⅲ、Ⅴ波存在者5耳（A级3耳，B级2耳），仅见Ⅰ波者5耳（B级2耳，C级3耳）。麻醉后手术前的监测显示：Ⅰ、Ⅲ、Ⅴ波存在者2耳，仅Ⅰ波存在者6耳，以复合动作电位（compound action potential，CAP）的N1波代替波Ⅰ；无波形者2耳。术后听力保留2耳，肿瘤均〈2cm，术前听力都为A级；连续听力监测显示1耳术中及术毕时Ⅰ、Ⅲ、Ⅴ持续存在，1耳Ⅰ、Ⅲ波存在，Ⅴ波消失；术后听力均为A级。听力未保留8耳，其中6耳术中监测时仅CAP的N1（波Ⅰ）存在，手术过程中夹内听动脉或处理内耳道处肿瘤时，4耳CAP波幅明显下降，甚至下降至0，术毕又恢复至术前的50％～60％或正常；1耳蜗神经与肿瘤一并切除，但CAP始终存在；1耳因牵拉脑干侧的耳蜗神经，CAP波幅降至0，手术结束亦未恢复。2耳为全身麻醉后术前监测中未引出任何波形者，其中1耳术中切除部分肿瘤后，出现CAP波，但波幅低，直至术毕；1耳始终未出现波形。结论联合应用ABR和ECochG术中监测，对提高听力保护率有积极意义，能及时反映术中与保留听力相关的敏感手术步骤，然而外科医师的熟练的解剖和精确的手术技巧是手术成功的最基本因素。     

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.     

Physiological identification of the auditory nerve during surgery for acoustic neuroma

We report the design and clinical use of an electrode which can locate the acoustic nerve fibres in the normal eighth nerve and also in eighth nerves deformed by acoustic neuromas. The improvement in facial nerve preservation during acoustic neuroma surgery is partly due to the use of a facial nerve stimulator to anatomically locate the fibres. Our new acoustic nerve detector has the capability of anatomical location of cochlear fibres which may help to improve hearing preservation in selected cases of acoustic neuroma. The device functions by detecting the compound action potential evoked by no frequency auditory simulation at 500 Hz. The 500 Hz compound action potential is detected with a bipolar probe and then amplified and filtered. This results in a 500 Hz tone when the probe contacts the auditory nerve. Detection is virtually instantaneous. The acoustic nerve detector (AND) is demonstrated in a normal eighth nerve complex and its use is then described in the total removal of an acoustic neuroma with a 1 cm extracanalicular extension in which useful hearing was saved post-operatively. The present prototype may not be sensitive enough to detect the very low signals that may result when cochlear fibres are widely distorted around a large tumour or in cases where slight contusion of the nerve occurs during dissection. In all other cases the real time anatomical information is extremely helpful in guiding acoustic nerve dissection and also in monitoring the effects of petrous bone drilling.     

Cranioplasty in acoustic neuroma surgery

OBJECTIVES: To measure the incidence of postoperative headaches after retrosigmoid resections of acoustic neuromas and to evaluate the impact of cranioplasty on the prevention and management of these headaches. STUDY DESIGN: A prospective evaluation was performed on 30 consecutive patients who underwent a cranioplasty after retrosigmoid excision of their acoustic neuroma. The results were compared with 30 historical control patients who underwent the same procedure but did not have reconstruction with a cranioplasty. The patients were evaluated by review of office records and via telephone questionnaire. METHODS: One group of patients (30 patients) had no cranioplasty, and the other group of 30 patients had primary reconstruction with a titanium mesh-acrylic cranioplasty. All 60 patients were asked to report on the duration and severity of their headaches by means of a standard questionnaire, grading their symptoms on a scale of 1 to 4. The data were subjected to chi2 and Student t test statistical analyses. RESULTS: New-onset, postoperative headaches occurred in 27% of patients, 23% in the cranioplasty group compared with 30% in the group without cranioplasty (a difference that was not statistically significant [P = .158]). However, there was a statistically significant difference in the severity of the headaches (P<.03). The headaches in the cranioplasty group were less severe and were not disabling. There were no complications, infections, or extrusions related to the cranioplasty. CONCLUSIONS: Cranioplasty has not been able to eliminate postoperative headaches. However, the use of cranioplasty has significantly decreased the severity of postoperative headaches after retrosigmoid excision of acoustic neuromas.     

Preoperative, intraoperative, and postoperative auditory evaluation of patients with acoustic neuroma

This article is a concise clinical review of preoperative, intraoperative, and postoperative auditory evaluation of patients with acoustic neuroma. The author describes behavioral audiometry, auditory brainstem response, and otoacoustic emissions for preoperative evaluation; auditory brainstem and direct eighth-nerve intraoperative monitoring for intraoperative evaluation; and touches on postoperative auditory assessment.     

Intraoperative monitoring of facial and cochlear nerves during acoustic neuroma surgery.

The likelihood of successful preservation of facial and cochlear nerve function during acoustic neuroma surgery has been improved by the advent of intraoperative monitoring techniques. The facial nerve is monitored by recording EMG from facial muscles, with no muscle relaxants used; mechanical irritation of the nerve during surgery causes increased EMG activity, which can be detected in real time using a loudspeaker. Brief episodes of activity associated with specific surgical maneuvers aid the surgeon in avoiding damage to the nerve, whereas prolonged tonic EMG activity may reflect significant neural injury. Electrical stimulation with a hand-held probe elicits evoked EMG responses, which can be used to locate and map the nerve in relation to the tumor. The threshold for eliciting evoked EMG responses provides a rough indicator of the functional status of the nerve. Different nerves in the posterior fossa (trigeminal, facial, spinal accessory) can be identified in multichannel recordings by the spatial distribution and latency of responses to electrical stimulation. The ability to elicit EMG responses from low amplitude stimulation of the facial nerve at the brain stem after tumor removal is a reasonable predictor of postoperative facial function. Cochlear nerve function is assessed by recording the ABR from ear canal and scalp electrodes or the CNAP with an electrode placed directly on the nerve at the brain stem root entry zone. The ABR is a well-known, noninvasive technique that can be adapted to intraoperative use relatively easily but is of limited utility owing to the delay inherent in signal averaging. Direct CNAP recordings require placement of an intracranial electrode in such a way as to contact the cochlear nerve without interfering with surgical access but have the distinct advantage of rapid feedback on changes in cochlear nerve status.     

Contralateral auditory brainstem response abnormalities in acoustic neuroma

Contralateral Auditory Brainstem Response (ABR) findings in a series of 79 patients with unilateral acoustic neuroma are presented. Sixty-four patients (81 per cent) had a normal contralateral ABR, thirteen (16.4 per cent) had latency abnormalities contralaterally and in two patients (2.6 per cent) no consistent responses could be recorded despite good hearing. Abnormalities in the contralateral ABR were analysed and five patients had abnormal III-V interwave intervals, in seven patients the I-III intervals were abnormal and in one patient, only the fifth wave was present and of abnormal latency. The tumour size was assessed by computed axial tomography (CT) and the relationship between tumour size and contralateral ABR findings established. Large tumours (greater than 2.5 cm.) were associated with contralateral ABR abnormalities in 25.6 per cent of the patients, medium tumours (1.0-2.5 cm.) with ABR abnormalities in 14 per cent and there were no abnormalities in the small group (intracanalicular). The implications for interpretation of ABR recordings contralateral to an acoustic neuroma are discussed in relation to brainstem compression and its effect on the wave generator sites.