电诱发听性脑干反应在人工耳蜗植入术后的临床应用分析[论著]

目的　探讨电诱发听性脑干反应（electrically evoked auditory brainstem responses，EABR）的特性和其在判断人工耳蜗植入术后听觉传导通路完整性中的作用，以及不同脉冲宽度的EABR阈值与人工耳蜗植入术后调试行为测试数值之间的相关性，为人工耳蜗植入术后首次开机不会配合行为测试的植入者科学设定刺激参数提供参考。方法　选取郑州市第三人民医院植入诺尔康晨星人工耳蜗（CS-10A植入体）、能配合行为测试的植入者20例，采用行为测试测得阈值（T值）和最大舒适阈（C值），在标准屏蔽室内做ABR检查，采用3、10、20电极分别测脉冲宽度为25、50、75 μs/相的EABR平均阈值，分析引出率和波形分化特点，并对两种数据进行统计学分析。结果　EABR越容易引出波形越清晰，患儿的听觉反应越灵敏，也反映了术后植入体系听觉传导通路越完整（P<0.05）；EABR脉冲宽度为75 μs/相的平均阈值与人工耳蜗的C值有良好的相关性（P<0.05）。结论　EABR检测可客观的判断人工耳蜗植入术后植入体系完整的听觉传导功能，客观评价人工耳蜗植入效果。人工耳蜗调试中，可以通过EABR脉冲宽度为75 μs/相的平均阈值来指导不能配合主观行为测试的植入者C值的判定，为患儿早期开始听觉刺激，建立听觉重塑带来帮助。     

人工耳蜗术后电诱发镫骨肌反射、神经反应电位与舒适阈值对比观察

目的 研究人工耳蜗植入患者电诱发镫骨肌反射阈值（electrically evoked stapedius reflex thresholds,ESRT)、电诱发听神经复合动作电位（electrically evoked compound actionpotential,ECAP）阈值与主观最大舒适阈（most comfortable level,M值）的相关性。方法 纳入2018年—2020年在解放军总医院耳鼻咽喉头颈外科医学部接受人工耳蜗植入的研究对象,42例人工耳蜗植入患者的43耳,年龄11～58岁,男22例,女20例,人工耳蜗植入体品牌型号分别澳大利亚Cochlear公司CI512型16例,奥地利MED-EL公司SONATAti100型或Mi10xx型23例,美国Advance Bionics公司HiRes90K型4例。通过人工耳蜗调机软件映射编程模块选择M值测量,获得各个电极通道主观最大舒适阈值。使用丹麦国际听力公司Titan听力测试平台中ESRT模块测得相同通道的植入耳同侧和对侧ESRT,再利用人工耳蜗调机软件ECAP测试模块测试相同通道ECAP阈值,分析三者间的相关性。结...     

电生理测试在力声特人工耳蜗调试中的应用

目的 分析电镫骨肌反射阈值(electrically evoked stapedius reflex threshold, ESRT)、电刺激听性脑干反应(electrically evoked auditory brainstem response, EABR)阈值、电刺激听神经复合动作电位(electrically evoked auditory nerve compound action potentials, ECAP)阈值与人工耳蜗心理物理量测试中的最大舒适阈值(maximum comfort threshold, C值)及最小反应阈值(minimum response threshold, T值)之间的关系，为力声特人工耳蜗植入者调试时参数设置提供参考。方法 选择14例具有一定响度辨别经验及言语交流能力且配合良好的语后聋力声特人工耳蜗植入者，平均年龄22.47±13.37岁，植入体型号为LCI-20PI。在每个患者开机后6±1个月时，选取人工耳蜗低频(1号)、中频(11号)、高频(19号)区域电极各一个，分别测试其T值、C值、ESRT、EABR及ECAP阈值，并进行相关性分...     

高频电诱发镫骨肌反射测试在人工耳蜗调试中的应用

目的探讨人工耳蜗术后高频(1000 Hz)探测音记录的电诱发镫骨肌反射(electrically evoked stapedius reflex,ESR)测试的特性及其阈值(electrically evoked stapedius reflex threshlod,ESRT)与最大舒适阈值(most comfortable level,C值)之间的关系。方法选取植入诺尔康CS-10A型人工耳蜗的患者26例,对受试者进行高频(1000 Hz)探测音记录的ESR测试,测试电极为2号、7号、12号、17号、23号,获取相应的ESRT,并记录常用程序中相应电极的C值。对5个电极间的ESRT进行重复测量方差分析,对ESRT和C值进行相关性和线性回归分析。结果26名受试者的120个电极可引出ESR,总引出率为92.3%;5个电极间的ESRT差异均有统计学意义(P<0.05),从蜗顶至蜗底呈上升趋势;5个电极的ESRT与C值均极显著相关(P<0.01)。结论高频(1000 Hz)探测音记录的ESRT可指导耳蜗和听神经形态正常及无其他植入禁忌症的诺尔康人工耳蜗植入患儿术后C值的调试。     

人工耳蜗植入患者电诱发镫骨肌反射的阈值及其临床意义

目的通过对人工耳蜗植入患者术后调试中进行主观心理物理测试和术中及术后电诱发镫骨肌反射阈值（electrically evoked stapedius reflex threshold，ESRT）的检测，探讨应用客观方法进行术后调试的临床应用价值，为人工耳蜗术后程序的调试提供客观依据。方法对2003年8月至2006年4月行Medel多道人工耳蜗系统Combi40＋型人工耳蜗植入的28例患者检测电诱发镫骨肌反射阈和开机调试中主观心理物理测试的最大舒适阈，比较两者之间的关系。结果对10例患者进行术中电诱发镫骨肌反射的检测，引出率为78．3％（94／120）。进行术后电诱发镫骨肌反射的检测，引出率为82．5％（99／120），3例大前前庭导水管综合征患者的引出率为47．2％（17／36）。28例患者按每个电极的术后最大舒适阈（maximu mcomfortable level，MCL）与ESRT进行比较：①术后MCL平均值大于ESRT为247个电极（80．5％）；②术后MCL值等于ESRT有14个电极（4．6％）；③术后MCL平均值小于ESRT有46个电极（15．0％）。术后ESRT平均值为（677．14-109．8）eu，MCL平均值为（732．34-114．8）cu，ESRT小于MCL（t=11．37，P〈0．05）。结论人工耳蜗植入术中观察到电诱发镫骨肌反射可以确切提示植入设备完好，由植入体至听觉中枢传导通路正常；电诱发镫骨肌反射阈值对术后开机调试有指导意义。     

不同脉宽条件下人工耳蜗植入者术中 电诱发听性脑干反应检测的特点分析

摘要：目的比较不同脉宽条件下人工耳蜗植入者术中电诱发听性脑干反应（electrically evoked auditory brainstem response,EABR）的特点,分析脉宽与EABR波V引出率和阈值之间的关系,总结不同脉宽条件对EABR波V引出率和阈值的影响,选择更优化的EABR脉宽测试参数。方法无残余听力的人工耳蜗植入患者24例作为实验组,其中耳蜗形态正常12例、大前庭导水管综合征（large vestibular aqueduct syndrome,LVAS）4例、Mondini畸形4例、共同腔畸形（common cavity deformation,CCD）2例、内听道狭窄2例;筛选条件相近的24例有残余听力的人工耳蜗植入者配对作为对照组。应用改装的Cochlear Freedom人工耳蜗及自制的铂铱合金球电极对拟行人工耳蜗植入的两组者术中分别给予50、100、200 μs不同脉宽的电刺激,Bio logic Navigator Pro听觉诱发电位仪记录不同脉宽条件下EABR波V引出率和阈值。结果脉宽50、100、200 μs时,EABR波V引出率实验组（均为91.7%）低于对照组（分别为100%、100%、95.8%）,差异无统计学意义（P均>0.05）;而EABR阈值实验组［分别为(183.73±8.96)CL、(151.28±10.05)CL、(120.56±12.82)CL］高于对照组［分别为(175.50±9.14)CL、(142.71±11.45)CL、(110.63±10.24)CL］,差异均具有统计学意义(t值分别为18.87、16.82、17.64,P均<0.05)。结论蜗内单极刺激能诱发出良好的EABR波形,无残余听力的患者EABR阈值要明显高于有残余听力的患者。相对于脉宽200 μs,50、100 μs时EABR波形波V引出率高;脉宽50 μs波形分化更好、动态范围广,内耳畸形严重可能需要适当加大刺激量（如将脉宽改为100 μs）。     

电诱发听性脑干反应（EABR）的临床应用

电诱发听性脑干反应（electrically evoked auditory brainstem responses，EABR）是一种客观的神经电生理检测方法．在耳科学、听力学和神经科学中占有重要的地位。EABR可以估测耳聋患者残存的听神经末梢螺旋神经节数量．客观评价听觉传导通路的功能状态．指导人工耳蜗植入手术及听性脑干植入手术．并在术后设备调试中起重要作用。本文对EABR的临床应用现状及前景做一综述。     

人工耳蜗植入者电诱发听性脑干反应阈值与行为测听阈值相关性研究

目的　通过对人工耳蜗植入者行为测听阈值和电诱发听性脑干反应（electrical evoked auditory brainstem response，EABR）阈值相关性比较，探讨用EABR波Ⅴ阈值 进行术后调试的可行性。方法　对19例（20耳）人工耳蜗植入者分别选取第1、6、11、16、22号刺激电极行EABR和行为测听测试，获得阈值。结果　刺激电极EABR波Ⅴ潜伏期为（3.73±0.37）ms；第1、6、11、16、22号电极EABR阈值分别为（145.50±9.85）、（144.75±7.69）、（148.25±11.04）、（146.50±9.20）和（142.25±10.45）CL；行为测听阈值分别为（138.95±7.87）、（138.20±9.04）、（136.50±9.32）、（137.90±10.23）和（134.40±13.43）CL。EABR阈值与行为测听阈值显著相关（r =0.533、0.671、0.580、0.749和0.811，P 均＜0.05）。结论　EABR阈值与行为测听阈值显著相关，EABR为低龄或无法配合行为测听的人工耳蜗植入者术后调机提供一种客观检测手段。     

ECAP检出与否的人工耳蜗植入患者的EABR表现

目的比较分析ECAP检出与否的耳蜗植入患者EABR特点,探讨EABR检测的意义。方法对26例人工耳蜗植入患者分别行神经反应遥测neural response telemetry,NRT）检测评估ECAP,并进行电诱发听洼脑干反应（electrically auditory evoked response,EABR）检测,将第20、10、3号电极均引出ECAP波形的14例患者纳入A组,未检出ECAP波形的12例患者纳入B组。对A、B两组患者的EABR阈值、V波潜伏期进行比较分析。结果A、B两组患者20、10、3号电极EABR阈值之间的差异有统计学意义（P〈0．001）,V波潜伏期之间的差异无统计学意义（P〉0．05）。结论ECAP波形引出与否人工耳蜗植入患者的EABR阈值有显著差异,v波潜伏期无明显差异。     

人工耳蜗植入患者电诱发镫骨肌反射检测

目的 寻找可靠的客观测定方法,在术中即时评价由植入体至听觉中枢传导通路的情况,并在术后协助人工耳蜗编程调试.方法 植入奥地利Combi 40＋型人工耳蜗系统的36位患者,使用CI.STUDIO＋2.0软件在术中进行电诱发镫骨肌反射（electrically evoked stapedius reflex,ESR）检测,分别选取第1、6、12电极作为观察蜗顶、蜗中、蜗底3个不同部位的研究电极,观察ESR检出率以及镫骨肌反射阈（electrically evoked stapediua reflex threshold,ESRT）与主观阈值（threshold,THR）、最大舒适级（maximum comfortable level,MCL）之间的关系.结果 ESR检出率为69.44%;各电极ESRT远远大于心理物理测试得到的主观阈值,接近最大舒适级,在THR和MCL动态范围的80%～90%左右,均值t检验ESRT与MCL无统计学差异（P〉0.05）.结论 ESR既可以用于术中判断植入体是否完好和听觉传导通路是否正常,预测手术效果,又可以在术后协助人工耳蜗编程调试,是一种方便、快捷的客观检查方法.     

The relationship between EAP and EABR thresholds and levels used to program the nucleus 24 speech processor: data from adults

OBJECTIVE: The objective of this study was to determine the relationship between electrically evoked whole nerve action potential (EAP) and electrical auditory brain stem response (EABR) thresholds and MAP threshold (T-level) and maximum comfort level (C-level) for subjects who use the Nucleus 24 cochlear implant system. DESIGN: Forty-four adult Nucleus 24 cochlear implant users participated in this study. EAP thresholds were recorded using the Neural Response Telemetry System developed by Cochlear Corporation. EABR thresholds were measured for a subset of 14 subjects using standard evoked potential techniques. These physiologic thresholds were collected on a set of five electrodes spaced across the cochlea, and were then compared with behavioral measures of T-level and C-level used to program the speech processor. RESULTS: EAP thresholds were correlated with MAP T- and C-levels; however, the correlation was not strong. A technique for improving the correlation by combining measures of T- and C-levels made on one electrode with the EAP thresholds was presented. Correlations between predicted and measured T- and C-levels using this technique were 0.83 and 0.77, respectively. Similar results were obtained using the EABR thresholds for a smaller set of subjects. In general, EABR thresholds were recorded at levels that were approximately 4.7 programming units lower than EAP thresholds. CONCLUSIONS: Either EAP or EABR thresholds can be used in combination with a limited amount of behavioral information to predict MAP T- and C-levels with reasonable accuracy.     

Usefulness of measuring electrically evoked auditory brainstem responses in children with inner ear malformations during cochlear implantation

Conclusions: EABR is a reliable and effective way of objectively confirming device function and implant-responsiveness of the peripheral auditory neurons up to the level of the brainstem in cases of inner ear malformation. Objective: To investigate the usefulness of measuring the intra-operative electrically evoked compound action potential (ECAP) and electrically evoked auditory brainstem response (EABR) in patients with and without congenital inner ear anomalies during cochlear implantation. Method: Thirty-eight consecutive children (40 ears) aged 5 or younger with congenital profound hearing loss. Twenty-four (25 ears) lacked congenital inner ear anomalies. The 14 patients (15 ears) with a malformation had common cavities (four ears), incomplete partition type I (three ears), cochlea hypoplasia type III (three ears), enlarged vestibular aqueduct (four ears), and cochlear nerve canal stenosis (one ear). Main outcome measures are ECAP and EABR responses. Results: Of the 25 ears lacking any malformation, 21, three, and one showed ‘Good’, ‘Variable’, and ‘No’ ECAP responses, respectively, and 24 and one showed ‘Good’ and ‘Variable’ intra-cochlear responses, respectively. Of the 15 ears with a malformation, two showed ‘Good’ ECAP responses, nine had ‘Variable’ ECAP responses, and four showed ‘No’ ECAP responses. Moreover, five showed ‘Good’ EABR responses and 10 showed ‘Variable’ EABR responses.     

Assessment of the functioning of peripheral auditory pathways after cochlear re-implantation in young children using intra-operative objective measures

The intra-operative electrical auditory brainstem response (EABR), electrical stapedius reflex threshold (ESRT) and the early post-operative behavioural threshold level (T-level) were recorded in five children undergoing cochlear re-implantation. The aim of the study was to assess objectively the effect of re-implantation on intra-operative objective measures and to investigate neuronal function. The children were aged between 2.06 years and 4.5 years at first implantation. Following failure of the first device, re-implantation was carried out 1.42-5.52 years later. Characteristics of the EABR and ESRT across the electrode array were typical of the expected pattern of responses on both occasions. In particular, the slopes of the amplitude input/output (I/O) functions for wave eV of the intraoperative EABR were similar for both the first and second implants even though absolute thresholds were generally elevated after re-implantation. This elevation in intra-operative threshold was more pronounced than the change in early post-operative behavioural threshold level for electrical stimulation (T-level). Our findings confirm a high level of neuronal survival after re-implantation. Threshold of the intra-operative EABR at the time of re-implantation greatly underestimates the sensitivity of the subsequent early post-operative T-levels.     

语前聋儿童人工耳蜗植入后的调机与声场评估

目的 调查语前聋儿童人工耳蜗植入术后声场主观测听阈值和对应T值的变化趋势。方法 28例人工耳蜗植入儿童。年龄3—6岁。无耳蜗畸形，植入后电极阻抗测试完全正常。对开机后3月、6月和1年时间的声场主观测听阈值与T值的变化进行了统计分析。结果 声场测听阈值在开机1年中呈逐渐降低趋势，开机1年时声场测听的听力水平较3个月和6个月有明显提高（P〈0．05）。植入者术后一年声场主观测听（啭音）听阈为15—35dB HL，听力水平较术前有明显提高。28例植入者T值在开机一年后明显低于六个月和三个月的水平（P〈0．05）。结论 开机后一年内T值和声场测听阈值都呈逐渐下降趋势．并且与3个月和6个月的水平差异具有统计学意义。植入者在熟悉适应了电声信号后，可以在刺激电流强度下降的同时获得更好的听力。     

Predicting cochlear implant outcomes in children with auditory neuropathy

OBJECTIVE: To examine the outcome of cochlear implantation in children with auditory neuropathy (AN) and cochlear nerve deficiency (Group A). Results are compared with a cohort of children with AN and normal cochlear nerves (Group B). STUDY DESIGN: Retrospective cohort study. SETTING: The Sydney Cochlear Implant Centre and the Children's Hospital at Westmead. PATIENTS: Children younger than 15 years with bilateral profound sensorineural hearing loss and the diagnosis of AN confirmed on electrophysiologic testing. All children underwent cochlear implantation with Nucleus 24 cochlear implants from 1997 to 2006. INTERVENTIONS: Magnetic resonance imaging was examined for deficiency of the vestibulocochlear nerve. Brain and inner ear abnormalities were recorded. Cochlear implant outcomes and demographic variables were compared. MAIN OUTCOME MEASURES: Melbourne speech perception score (MSPS) at 1 year and implant evoked electric auditory brainstem response (EABR). RESULTS: Group A performed significantly worse on both parameters than Group B. In Group A, median MSPS was 1, compared with a median score of 4 in Group B (z = -3.010; p = 0.003). EABR was abnormal in 13 of 15 (87%) children in Group A, compared with 9 of 39 (23%) in Group B. Children in both groups with abnormal EABR had significantly worse MSPS (z = -2.780; p = 0.005). Fourteen of 15 children with cochlear nerve deficiency had associated inner ear abnormalities. CONCLUSION: Children with AN can have associated cochlear nerve deficiency. These patients have worse speech perception scores at 1 year post cochlear implantation, higher rates of abnormal EABR, and more associated inner ear abnormalities than children with AN and normal cochlear nerves.     

Activity-dependent developmental plasticity of the auditory brain stem in children who use cochlear implants

OBJECTIVES: 1) To determine if a period of early auditory deprivation influences neural activity patterns as revealed by human auditory brain stem potentials evoked by electrical stimulation from a cochlear implant. 2) To examine the potential for plasticity in the human auditory brain stem. Specifically, we asked if electrically evoked auditory potentials from the auditory nerve and brain stem in children show evidence of development as a result of implant use. 3) To assess whether a sensitive or critical period exists in auditory brain stem development. Specifically, is there an age of implantation after which there are no longer developmental changes in auditory brain stem activity as revealed by electrically evoked potentials? DESIGN: The electrically evoked compound potential of the auditory nerve (ECAP) and the electrically evoked auditory brain stem response (EABR) were recorded repeatedly during the first year of implant use in each of 50 children. The children all had pre- or peri-lingual onset of severe to profound sensorineural hearing loss and received their implants at ages ranging from 12 mo to 17 yr. All children received Nucleus cochlear implant devices. All children were in therapy and in school programs that emphasized listening and required the children to wear their implants consistently. RESULTS: Initial stimulation from the cochlear implant evoked clear responses from the auditory nerve and auditory brain stem in most children. There was no correlation between minimum latency, maximum amplitude, or slope of amplitude growth of initial responses with age at implantation for ECAP eN1, EABR eIII and eV components (p > 0.05). During the first year of implant use, minimum latency of these waves significantly decreased (p < 0.01, p < 0.0001, p < 0.0001, respectively). Neural conduction time, measured using the interwave latency of ECAP eN1-EABR eIII for lower brain stem and EABR eIII-eV for upper brain stem, decreased during the period of 6 to 12 mo of cochlear implant use (p < 0.01 (lower), p < 0.0001(upper)). The ECAP wave eN1 and the EABR wave eV showed significant increases in amplitude during time of implant use (p < 0.05 and p < 0.01, respectively). There were no correlations between the rate of interwave latency decrease and the rate of amplitude increases and the age at which children underwent implantation (p < 0.05). CONCLUSIONS: Activity in the auditory pathways to the level of the midbrain can be evoked by acute stimulation from a cochlear implant. EABR measures are not influenced by any period of auditory deprivation. Auditory development proceeds once the implant is activated and involves improvements in neural conduction velocity and neural synchrony. Underlying mechanisms likely include improvements in synaptic efficacy and possibly increased myelination. The developmental plasticity that we have shown in the human auditory brain stem does not appear from EABR data to be limited by a critical period during childhood.     

Toward a battery of behavioral and objective measures to achieve optimal cochlear implant stimulation levels in children

OBJECTIVES: Children require audible and comfortable stimulation from their cochlear implants immediately after device activation. To accomplish this, a battery of objective measures may be needed that could include the electrically evoked stapedius reflex (ESR), compound action potential from the auditory nerve (ECAP), and/or auditory brain stem response (EABR). In the present study, the following specific research questions were asked: In children using cochlear implants, 1) Can the ECAP, EABR, and ESR be recorded at the time of cochlear implantation? 2) What is the feasibility of measuring the ECAP, EABR, and the ESR repeatedly without the use of sedation over the first year of implant use? 3) Do ECAP, EABR, and ESR thresholds or behavioral measures change over time? 4) What is the relation between ECAP, EABR, and ESR thresholds and behavioral measures of threshold and comfortably loud levels? DESIGN: In 68 children, ECAP, EABR, and ESR responses as well as behavioral measures of stimulation threshold and maximum stimulation were recorded at regular intervals over the first year of implant use. In each child, responses were recorded to electrical pulses provided by three different electrodes along the implanted array. Visual inspections of the stapedius reflex (V-ESR) evoked by activation of the same three electrodes at the time of surgery were performed in an additional 20 children. RESULTS: ECAP and EABR measures were obtained in more than 84% of electrodes tested and 89% of children tested both in the operating room at the time of implant surgery (OR) and after surgery in nonsedated children. ESRs were recorded by using immittance measures in more than 65% of electrodes tested and 67% of children tested by 3 mo of implant use, but this technique was less successful in the OR and during early stages of device use. V-ESRs and ECAP thresholds were higher in the OR than ESRs and ECAPs at postoperative recording times. EABR and ECAP thresholds did not significantly change over the first 6 and 12 mo of implant use, respectively, whereas ESR thresholds increased. Behavioral measures of threshold decreased over time, whereas maximum stimulation levels rose over time. Behavioral measures of threshold and loudness were highly correlated at all test times. ECAP, EABR, and behavioral measures were lower when evoked by an electrode at the apical end of the implanted array than by more basal electrodes. Behavioral thresholds could be predicted mainly by ECAP thresholds, whereas maximum stimulation levels could best be predicted by ESR thresholds; both were significantly affected by the age at implantation. CONCLUSIONS: A combination of nonbehavioral measures can aid in the determination of useful cochlear implant stimulation levels, particularly in young children and infants with limited auditory experience. These measures can be made in the operating room and can be repeated after surgery when needed. Correction factors to predict threshold stimulation levels should be based on ECAP thresholds or EABR thresholds if necessary. Correction factors should be made for at least one apical and mid-array electrode, should take into account the age of the child, and may have to be revised during the first year of implant use. Maximum stimulation levels may be best determined by using the ESR.     

A clinical study of electrophysiological correlates of behavioural comfort levels in cochlear implantees

Abstract

Objectives

Indications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioural responses may be tedious for audiologists in such cases, wherein matching an effective Measurable Auditory Percept (MAP) and appropriate MAP becomes the key issue in the habilitation program. In ‘Difficult to MAP’ scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed to (a) study the trends in multi-modal electrophysiological tests and behavioural responses sequentially over the first year of implant use; (b) generate normative data from the above; (c) correlate the multi-modal electrophysiological thresholds levels with behavioural comfort levels; and (d) create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis.

Methods

This prospective study included 10 profoundly hearing impaired children aged between 2 and 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90 K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, impedance telemetry, neural response imaging, electrically evoked stapedial response telemetry (ESRT), and electrically evoked auditory brainstem response (EABR) tests at 1, 4, 8, and 12 months of implant use, in conjunction with behavioural mapping. Trends in electrophysiological and behavioural responses were analyzed using paired t-test. By Karl Pearson's correlation method, electrode-wise correlations were derived for neural response imaging (NRI) thresholds versus most comfortable level (M-levels) and offset based (apical, mid-array, and basal array) correlations for EABR and ESRT thresholds versus M-levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-levels were compared with the behaviourally recorded M-levels among the cohort, using Cronbach's alpha reliability test method for confirming the efficacy of this method.

Results

NRI, ESRT, and EABR thresholds showed statistically significant positive correlations with behavioural M-levels, which improved with implant use over time. These correlations were used to derive predicted M-levels using regression analysis. On an average, predicted M-levels were found to be statistically reliable and they were a fair match to the actual behavioural M-levels. When applied in clinical practice, the predicted values were found to be useful for programming members of the study group. However, individuals showed considerable deviations in behavioural M-levels, above and below the electrophysiologically predicted values, due to various factors. While the current method appears helpful as a reference to predict initial maps in ‘difficult to Map’ subjects, it is recommended that behavioural measures are mandatory to further optimize the maps for these individuals.

Conclusion

The study explores the trends, correlations and individual variabilities that occur between electrophysiological tests and behavioural responses, recorded over time among a cohort of cochlear implantees. The statistical method shown may be used as a guideline to predict optimal behavioural levels in difficult situations among future implantees, bearing in mind that optimal M-levels for individuals can vary from predicted values. In ‘Difficult to MAP’ scenarios, following a protocol of sequential behavioural programming, in conjunction with electrophysiological correlates will provide the best outcomes.     

Pre-perioperative, transtympanic electrically evoked auditory brainstem response in children

The purpose of this study was to characterize the transtympanically evoked, perioperative electrically evoked auditory brainstem response (EABR) and define its relationship with preoperative hearing, age and hearing loss etiology in 59 children (10-60 months of age) who had received cochlear implants. The results indicate that there was no difference between wave V latency obtained from the younger (10-36 months) and the older (37-60 months) children. There was a statistically significant difference in the preoperative pure-tone average between the higher-EABR threshold group (650 microA and above) and the lower-EABR threshold group (600 microA or less). Patients with post-meningitic deafness exhibited the longest EABR wave V latencies. Perioperative, transtympanic, promontory EABR is an effective clinical procedure which can decrease the likelihood of placing a cochlear implant in a non-stimulable ear, and may provide the clinician with a valuable tool for selecting the most appropriate ear for implantation.