Summary of results using the nucleus CI24M implant to record the electrically evoked compound action potential

OBJECTIVE: This study outlines a series of experiments using the neural response telemetry (NRT) system of the Nucleus CI24M cochlear implant to measure the electrically evoked compound action potential (EAP). The goal of this investigation was to develop a protocol that allows successful recording of the EAP in a majority of CI24M cochlear implant users. DESIGN: Twenty-six postlingually deafened adults participated in this study. A series of experiments were conducted that allowed us to examine how manipulation of stimulation and recording parameters may affect the morphology of the EAP recorded using the Nucleus NRT system. RESULTS: Results of this study show consistent responses on at least some electrodes from all subjects. Cross-subject and cross electrode variations in both the growth of the response and the temporal refractory properties of the response were observed. The range of stimulus and recording parameters that can be used to record the EAP with the Nucleus NRT system is described. CONCLUSIONS: Using the protocol outlined in this study, it is possible to reliably record EAP responses from most subjects and for most electrodes in Nucleus CI24M cochlear implant users. These responses are robust and recording these responses does not require that the subject sleep or remain still. Based on these results, a specific protocol is proposed for measurement of the EAP using the NRT system of the CI24M cochlear implant. Potential clinical implications of these results are discussed.     

Advantage of accelerated fractionation regimens in definitive radiotherapy for stage II glottic carcinoma

OBJECTIVES: We evaluated the prognostic factors for local control of T2 glottic cancer and verified the efficacy of accelerated fractionation regimens such as hyperfractionation and accelerated hyperfractionation. METHODS: A total of 86 patients with T2 N0 M0 glottic squamous cell carcinoma, who were treated with definitive radiotherapy, were analyzed retrospectively by multivariate analysis. RESULTS: Overall treatment time of radiotherapy (p = .0003) and total dose (p = .0036) were the significant prognostic factors for local control on multivariate analysis. The group with a higher total dose (> or = 67 Gy versus <67 Gy) showed a favorable prognosis (5-year local control rate of 91% versus 60%, respectively; p = .0013, log-rank test). Likewise, the group with a shorter overall treatment time of radiotherapy (< or = 54 days versus >54 days) showed a favorable prognosis (5-year local control rate of 87% versus 71%, respectively; p = .023). CONCLUSIONS: A radiotherapy total dose of > or = 67 Gy delivered for a shorter period is required for T2 glottic cancer. The fractionation regimens of hyperfractionation and accelerated hyperfractionation are more effective than conventional fractionation in terms of shortening overall treatment time and delivering a high total dose with acceptable toxicity.     

多导人工耳蜗植入后电极阻抗的初步研究

目的研究多导人工耳蜗植入后电极阻抗变化的特点,对比直电极和弯电极的阻抗差异,为人工耳蜗植入术后的调试提供参考。方法在Nucleus多导人工耳蜗编程调试界面上,应用R126V1.3和NRTV3.0软件,测试11例语前聋儿童在不同时期的阻抗值,并进行分析比较。结果CI24M和CI24Rcontour两种植入体阻抗随时间变化的基本规律是:术中较低,开机时最高,以后随时间推移逐渐降低。CI24Rcontour阻抗高于CI24M。结论人工耳蜗植入体阻抗开机后随时间推移而逐渐降低,新型CI24Rcontour植入体与CI24M相比,其阻抗值在术中至开机后3周内明显要高。     

Sensitivity and specificity of averaged electrode voltage measures in cochlear implant recipients

OBJECTIVE: The primary purpose of this study was to evaluate the diagnostic accuracy of averaged electrode voltages (AEVs) for identifying malfunctioning electrodes in cochlear implant users. DESIGN: AEVs were measured using common ground (N = 33 ears) and monopolar stimulation modes (N = 40 ears) in adult subjects implanted with the Nucleus 24M or Nucleus 24R(CS) cochlear implant. AEV measures were then compared with common ground electrode impedance measures as well as to subjective judgments of electrode sound quality to determine the sensitivity and specificity of AEVs. RESULTS: Results showed excellent specificity for both modes of AEV testing: 97.9% for common ground and 99.8% for monopolar. Sensitivity for common ground AEV testing was 91.7%; however the sensitivity of monopolar AEVs was very poor, at 7.7%. Monopolar AEVs accurately identified open circuits but missed all short circuits. These results are consistent with the sensitivity of impedance measures made with each of the two stimulation modes. CONCLUSIONS: Common ground AEVs are more reliable than monopolar AEVs for identifying malfunctioning electrodes.     

Neural response telemetry with the nucleus CI24M cochlear implant

OBJECTIVES: To review our intraoperative and postoperative testing protocol for cochlear implant patients. This study describes the methodologies and applications of a new technique called neural response telemetry (NRT) for the Nucleus CI24M cochlear implant system. NRT uses radiofrequency telemetry technology to measure the action potentials of the auditory nerve. STUDY DESIGN: We have developed a specific protocol for intraoperative testing of the implant device before, during, and after implantation. This includes device integrity tests, visual detection of electrical stapedius muscle reflexes (VESR), and NRT. METHODS: Our methodologies use the commercial software (Windows-based Diagnostic and Programming System [WIN-DPS] and NRT) for the Nucleus CI24M. We describe the details of our protocol used on all of the patients (14 adults and 14 children) who received CI24M implants at Mayo Clinic (Rochester, MN). Our protocol correlates the NRT threshold with the behavioral responses for each patient on at least four electrodes. RESULTS: From August 1, 1998, to December 31,1998, we completed electrode integrity tests, NRT, and VESR testing intraoperatively on 12 patients with the Nucleus CI24M. We have measured normal implant function on all 28 of our CI24M patients with one exception. One of our children had a device failure after approximately 4 months as a result of head trauma. We have also obtained NRT results from an additional 10 patients postoperatively. CONCLUSIONS: The measurement of device and electrode array function is quite simple with the CI24M software. These measurements can be obtained intraoperatively as well as postoperatively. We conclude that VESR and NRT measurements can be very helpful in programming for patients with cochlear implants, especially children, because they provides us with target settings for the speech processor.     

Early results using the nucleus CI24M in children

OBJECTIVE: To report early postimplantation speech recognition results in children who received Nucleus CI24M cochlear implants. STUDY DESIGN: The study group consisted of 19 consecutively implanted children. PATIENTS AND SETTING: Congenitally deaf children (20 months to 15 years old) were implanted with the Nucleus CI24M and followed-up at New York University Medical Center for a period of 3 to 12 months. MAIN OUTCOME MEASURES: Speech perception was evaluated preoperatively and postoperatively using the Early Speech Perception (ESP) test, the Glendonald Auditory Screening Procedure (GASP) word and sentence tests, Phonetically Balanced Kindergarten (PBK) monosyllabic word lists, Common Phrases test, the Multisyllabic and Lexical Neighborhood (MLNT, LNT) tests, and the Banford-Kowal-Bench (BKB) sentence test. RESULTS: One-way analyses of variance revealed significant improvement in open-set speech recognition in children able to perform measurement tasks. CONCLUSIONS: The Nucleus CI24M cochlear implant provides significant benefit to children after short-term use.     

Nucleus人工耳蜗弯电极和直电极植入后的心理物理指标比较

目的对比Nucleus CI 24导Contour弯电极与Nucleus CI 24导直电极植入后的电阻阻抗、刺激阈值和舒适阈。方法植入澳大利亚NucleuS人工耳蜗的患者分为2组,1组（19例）植入Nucleus CI 24导Contour电极阵列（弯电极）,另1组（11例）植入CI 24M电极阵列（直电极）。所有患者耳蜗植入术后15天开机调试,并于开机时及开机后1周、1月、3月分别记录各电极的电阻、刺激闽值和最大舒适阈。结果开机后由于Nucleus 24直电极的刺激阈值呈上升趋势,3月和6月时弯电极的阈值明显低于直电极阈值,且差异有统计学意义（P〈0．05）。开机1周、1月和6月2组的舒适阈接近。开机后弯电极和直电极的电阻值接近。结论Nucleus CI 24导Contour弯电极的刺激阈值稳定,刺激阈和舒适阈之间动态范围较宽。     

Comparison of electrically evoked whole-nerve action potential and electrically evoked auditory brainstem response thresholds in nucleus CI24R cochlear implant recipients

In this study, differences between electrically evoked whole-nerve action potential (EAP) and electrically evoked auditory brainstem response (EABR) measurements within Nucleus CI24R cochlear implant recipients were evaluated. Precurved modiolus-hugging internal electrode arrays, such as the CI24R, are designed to provide more direct stimulation of neural elements of the modiolus. If the electrode array is closer to the modiolus, electrically evoked and behavioral levels might be lower than were previously recorded for the straight electrode array, the CI24M. EAP and EABR growth functions and behavioral levels were obtained for 10 postlingually deafened adults. Results revealed no significant differences between EAP and EABR threshold levels, and these levels were not significantly lower than those obtained using the CI24M.     

Nucleus24型人工耳蜗使用者电诱发听神经复合动作电位的测定

目的 :探讨电诱发听神经复合动作电位 (ECAP)的特点及在人工耳蜗临床中的应用价值和意义。方法 :应用NRT(neuralresponsetelemetry)软件 ,通过体外言语处理器和耳蜗内的植入电极系统 ,采用单极模式电极刺激和近场记录方法 ,对 37例NucleusCI2 4M装置使用者进行ECAP的记录。对其中 12例使用者做了行为测试。结果 :87.6 %的使用者记录到ECAP波形。分析了有行为阈值的 12例测试者的ECAP阈值和行为阈值的关系 ,二者之间存在显著的相关性。结论 :ECAP的检出率高且波形稳定可靠 ,在临床人工耳蜗装置的调试中可作为对行为测试的补充 ;对于年幼儿童和首次开机的患者的调试尤其重要     

Clinical outcomes cochlear reimplantation

To clarify the clinical features of cochlear reimplantation and surgical changes in auditory performance, we retrospectively reviewed 10 of 252 cochlear implantation surgeries-6 adults and 4 children-among 129 children and 123 adults done between April 1987 and May 2009. Mean duration from initial implantation to reimplantation was 50.3 months in children and 89 months in adults, most commonly due to hard failure and implant exposure/infection (33%) in children and to hard failure (75%) in adults. The initial device implanted was the Nucleus multichannel implant (CI22M, CI24M, or CI24R). The second implant in 7 was the same or an upgrade of the same manufacturer's device, and in 2 children the HiRes 90K (Hifocus 1j) and in 1 adult the Clarion 1.2. Full initial and reinsertion succeeded in 8 cases but reinsertion proved difficult in 2 due to severe intracochlear granulation and osteoneogenseis. Auditory performance analyzed in 7 cases was mostly equal to or better than before reimplantation, although differences were not statistically significant. Reinsertion is rarely difficult, but electrode choice is important in preparing for difficult reinsertion. Post reinsertion auditory performance is satisfactory with some exceptions.     

Estimation of psychophysical levels using the electrically evoked compound action potential measured with the neural response telemetry capabilities of Cochlear Corporation's CI24M device.

OBJECTIVE: The goal of this study was to estimate psychophysical levels using the electrically evoked compound action potential (EAP), measured with the Neural Response Telemetry capabilities of Cochlear Corporation's Nucleus CI24M cochlear implant system. DESIGN: Twelve postlingually deafened adults with at least 3 mo of implant experience with the CI24M were subjects in this study. EAP growth functions were successfully quantified on each active electrode of every subject. Correlation and regression analyses were performed between EAP measures and cochlear implant fitting psychophysics. Other information including performance, etiology and duration of hearing loss, and individual electrode impedance was considered. RESULTS: EAP thresholds were found to be highly correlated with psychophysical thresholds. The rate of EAP growth with increasing stimulation levels was also found to be correlated with the dynamic range of loudness limits and psychophysical thresholds in some subjects. No relationship was evident between EAP measures and speech perception tests. CONCLUSIONS: Information from EAP growth function measurements may be used to estimate psychophysical information used in cochlear implant fitting but not to predict performance with the device.     

多道人工耳蜗植入533例临床分析

OBJECTIVE: To summarize and analyze the etiology, surgical indications, operation methods and outcomes of cochlear implantation. METHODS: 533 cases (534 ears) with severe and profound hearing loss received cochlear implant, 489 were pre-lingual deafness and 38 cases were post-lingual deafness. Their ages at implant, 1 to approximately 3 were 167, approximately 5 were 77, approximately 7 were 73, approximately 14 were 136, approximately 17 were 28, >17 were 52. 76 cases (14. 3%) were found the middle and inner ear malformations. That included Mondini 26 in cases, Common cavity in 10 cases and Large vestibule aqueduct syndrome in 20 cases. The average pure tone threshold were 105.5 dB HL, ABR threshold were >95 dB nHL and 40 Hz threshold in 500 Hz were 101.7 dB. The devices they used were Nucleus 22M in 27 ears, 24M in 308 ears, 24R Contour in 131 ears and 24R ST in 21 ears; Med El C40+ in 44 ears; Clarion CI in 3 ears. Facial recess approach was performed in normal cases, and in Common cavity cases horizontal semicircular canal approach was used. Preoperative hearing and speech evaluations were done in most cases. RESULTS: In 26 Mondini case, gusher were happened in 20 cases. The insertion depth in normal cases: Nucleus were 30 bands, Med El were 31 mm. In Mondini cases, Nucleus were 28 bands. In Common cavity cases, Nucleus were 26 bands. Of 533 cases, The average of open set sentences discrimination of post-lingual deadness was 70%, the satisfaction rate of questionnaire for pre-lingual deafness under 17 years old was 94.7%. CONCLUSIONS: Cochlear implant is a useful method to restore the hearing of the patients with severe and profound hearing loss. It is important for the outcomes with proper preoperative assessment, surgery and postoperative speech and hearing evaluations.     

Auditory localization abilities in bilateral cochlear implant recipients.

OBJECTIVE: To quantify binaural advantage for auditory localization in the horizontal plane by bilateral cochlear implant (CI) recipients. Also, to determine whether the use of dual microphones with one implant improves localization. METHODS: Twenty subjects from the UK multicenter trial of bilateral cochlear implantation with Nucleus 24 K/M device were recruited. Sound localization was assessed in an anechoic room with an 11-loudspeaker array under four test conditions: right CI, left CI, binaural CI, and dual microphone. Two runs were undertaken for each of five stimuli (speech, tones, noise, transients, and reverberant speech). Order of conditions was counterbalanced across subjects. RESULTS: Mean localization error with bilateral implants was 24 degrees compared with 67 degrees for monaural implant and dual microphone conditions (chance performance is 65 degrees). Normal controls average 2 to 3 degrees in similar conditions. Binaural performance was significantly better than monaural performance for all subjects, for all stimulus types, and for different sound sources. Only small differences in performance with different stimuli were observed. CONCLUSIONS: Bilateral cochlear implantation with the Nucleus 24 device provides marked improvement in horizontal plane localization abilities compared with unilateral CI use for a range of stimuli having different spectral and temporal characteristics. Benefit was obtained by all subjects, for all stimulus types, and for all sound directions. However, binaural performance was still worse than that obtained by normal hearing listeners and hearing aid users with the same methodology. Monaural localization performance was at chance. There is no benefit for localization with dual microphones.     

多道人工耳蜗植入533例临床分析

目的 分析人工耳蜗植入患者的手术适应证、手术方法和术后效果。方法 533例(534耳)重度和极重度聋患者接受人工耳蜗植入手术。其中语前聋495例,语后聋38例。植入时年龄:1～3岁167例,～5岁77例,-7岁73例,-14岁136例,～17岁28例,>17岁52例。内耳中耳畸形共76例,其中Mondini畸形26例、共同腔畸形10例、前庭水管扩大综合征20例。术前纯音听阈(听力级)为105.5 dB,听性脑干反应阈>95 dB,40 Hz相关电位(500 Hz)>101.7 dB。使用装置:Nucleus 22M 27耳,24M 308耳,24R Contour 131耳,24RST 21耳;Med El C40 44耳;Clarion CI 3耳。常规手术采用面隐窝进路方法。共同腔畸形病例采用经水平半规管进路。部分病例行术后声场测听和听觉言语评估。结果 Mondini畸形26例中有20例术中出现脑脊液井喷。电极平均植入深度:耳蜗正常病例中Nucleus 30环,Med El为31 mm。Mondini畸形病例中Nucleus 28环。共同腔畸形病例中Necleus 26环。语后聋患者的平均开放言语识别率为71％,17岁以下语前聋的问卷调查满意度为94.7％。结论 人工耳蜗是使重度和极重度聋患者恢复听觉功能的有效方法,术前评估,手术和术后康复都是治疗效果的关键。     

Across-site threshold variation in cochlear implants: relation to speech recognition

Functional implications of across-site variation in detection thresholds in subjects with cochlear implants were evaluated by comparing thresholds to speech recognition performance. Detection thresholds for bipolar (BP) and monopolar (MP) stimulation of all available stimulation sites were assessed in 21 subjects with Nucleus CI24M and CI24R(CS) implants. We found significant negative correlations between speech recognition and within-subject across-site threshold variance for both BP and MP stimulation, but no significant correlation of speech recognition with mean threshold levels. These results suggest that across-site variance of detection thresholds could provide a useful early indication of the prognosis for speech recognition and might serve as an indicator for specific therapeutic approaches in individual subjects.     

The effect of large single radiation doses on cochlear implant function: implications for radiosurgery

The purpose of this study was to investigate the effect of large single doses of radiation on the function of a cochlear implant. A cochlear implant (Nucleus^® 24 k, Cochlear Ltd., Sydney, Australia) was implanted into a cadaver head and tested for functional changes following irradiation. Within 2 h, the device was given single fractions of 16.3 Gy, 6.2 Gy and 20 Gy with 6 MV photons. The size of the fractions was derived from maximum doses registered in linear accelerator-based radiosurgery of more than 300 patients treated for benign or malignant tumors at the Department of Radiation Therapy of the University Hospital of Freiburg. After each treatment an integrity test was performed testing the impedance and current output of the CI system. The total dose of 42.5 Gy caused no changes with regard to the tested parameters. The risk of implant failure seems to be low for Nucleus^® 24 k cochlear implants exposed to large single doses of radiation as used in radiosurgery.     

小儿耳蜗植入后电诱发复合动作电位的阈值及其临床应用

目的：研究应用神经反应遥测（neural response telemetry,NRT)技术，测试电诱发复合动作电位（electrically-evoked compound action potential,ECAP)阈值以指导小儿人工耳蜗映射调图的策略与时机。方法：应用NRT3．0软件对辐值增长函数进行线性拟合，确定ECAP阈值。比较6例儿童植入者在术后1、2、3个月ECAP阈值的变化，同时比较了7例儿童术中、术后ECAP阈值的差异。结果：ECAP幅值增长函数在接近阈值或进入饱和时不再呈线性。术后ECAP阈值保持稳定。各导电极的术中ECAP阈值比术后阈值平均高约15CL，二者有显著性相关（R2＝0．9154）。结论：应选取幅值增长函数的直线段部分进行拟合以确定ECAP阈值。术后应用ECAP阈值指导小儿映射调图时，测试一次ECAP阈值即可。术中ECAP阈值可用作开机时映射图的C值。     

人工耳蜗植入术后电极阻抗特性分析

目的对使用人工耳蜗系统患者的电极阻抗数值进行分析,总结电极阻抗的变化规律,为临床制定合理的术后调试计划提供依据。方法对152位使用澳大利亚Cochlear Nucleus24M型人工耳蜗系统的患者于术后4周左右安装体外设备并进行测试,使用澳大利亚Cochlear公司提供的R116或R126软件进行电极阻抗测试。结果患者电极阻抗数值自术中至术后开机时呈显著增加的趋势,在开机时达到最大,其后随开机时间的增长显著降低,至开机3个月后趋于稳定,不同部位的电极显示了相同的变化趋势。结论电极阻抗数值随术后使用时间及电极部位的变化而变化。在开机3个月内需多次进行调试,从而为患者提供最适合的程序,使患者的言语感知达到最佳状态。     

Comparison of speech perception performance between the Nucleus 24 and Nucleus 24 Contour cochlear implant systems

OBJECTIVE: To compare the 1-, 3-, and 6-month postoperative speech perception scores obtained by a group of subjects who received the new perimodiolar array (Nucleus Contour) cochlear implant with those obtained by a group of subjects implanted with the straight electrodes of the previous-generation Nucleus 24 device. MATERIAL AND METHODS: The speech performance of 10 postlingually deafened adults implanted with the Nucleus Contour device was compared with that of matched controls who received the Nucleus 24 model. Objective measures included word and sentence speech recognition scores. RESULTS: Patients implanted with the Nucleus Contour device obtained significantly higher word and sentence recognition scores after short-term use of the implant compared to those obtained by patients implanted with the Nucleus 24 model. CONCLUSION: Further long-term studies are required to determine whether the Nucleus Contour CI recipients continue to improve over time.     

TNRT profiles with the Nucleus Research Platform 8 system

This study investigates the effect of the Nucleus CI24RE implant's neural response telemetry (NRT) system, which has less internal noise compared to its predecessor, the CI24M/R implant, on the NRT threshold (TNRT) profile across the array. CI24M/R measurements were simulated by ignoring CI24RE measurements with response amplitudes below 50 uV. Comparisons of the estimated TNRTs from the CI24RE measurements and the CI24M/R simulations suggest that, apart from a constant level difference, the TNRT profiles from the newer implant generally would not have differed very much from those of its predecessor. This view was also reflected by principal component analysis (PCA) results which revealed a ‘shift’ component similar to that reported by Smoorenburg et al (2002). On the whole, there is no indication that current practices of using the TNRT profiles for assisting with speech processor programming need to be revised for the CI24RE implant.