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Objectives The primary goal of the study was to investigate electrical cortical auditory evoked potentials (eCAEPs) at maximum comfortable level (MCL) and 50% MCL on three cochlear implant (CI) electrodes and compare them with the acoustic CAEP (aCAEPs), in terms of the amplitude and latency of the P1-N1-P2 complex. This was achieved by comparing the eCAEP obtained with the method described and stimulating single electrodes, via the fitting software spanning the cochlear array and the aCAEP obtained using the HEARLab system at four speech tokens. Design Twenty MED-EL (MED-EL Medical Electronics, Innsbruck, Austria) CI adult users were tested. CAEP recording with HEARLab System was performed with speech tokens /m/, /g/, /t/, and /s/ in free field, presented at 55 dB SPL. eCAEPs were recorded with an Evoked Potential device triggered from the MAX Programming Interface (MED-EL Medical Devices) with 70 msec electrical burst at 0.9 Hz at the apical (1), middle (6), and basal (10 or 11) CI electrode at their MCL and 50% MCL. Results CAEP responses were recorded in 100% of the test subjects for the speech token /t/, 95% for the speech tokens /g/ and /s/, and 90% for the speech token /m/. For eCAEP recordings, in all subjects, it was possible to identify N1 and P2 peaks when stimulating the apical and middle electrodes. This incidence of detection decreased to an 85% chance of stimulation at 50% MCL on the same electrodes. A P1 peak was less evident for all electrodes. There was an overall increase in latency for stimulation at 50% MCL compared with MCL. There was a significant difference in the amplitude of adjacent peaks (P1-N1 and N1-P2) for 50% MCL compared with MCL. The mean of the maximum cross-correlation values were in the range of 0.63 to 0.68 for the four speech tokens. The distribution of the calculated time shift, where the maximum of the cross-correlation was found, was distributed between the speech tokens. The speech token /g/ had the highest number of valid cross-correlations, while the speech token /s/ had the lowest number. Conclusions This study successfully compared aCAEP and eCAEP in CI users. Both acoustic and electrical P1-N1-P2 recordings obtained were clear and reliable, with good correlation. Latency increased with decreasing stimulation level, while amplitude decreased. eCAEP is potentially a better option to verify speech detection at the cortical level because it (1) uses direct stimulation and therefore creates less interference and delay of the sound processor and (2) creates more flexibility with the recording setup and stimulation setting. As such, eCAEP is an alternative method for CI optimization.

Prior to cochlear implantation, audiological tests are performed to determine candidacy in subjects with a hearing loss. This is usually done by measuring the acoustic auditory brainstem response (ABR). Unfortunately, for some subjects, a reproducible ABR recording cannot be obtained, even at high acoustic levels. Having a healthy stimulating auditory nerve is required for cochlear implantation in order to benefit from the electrical pulses that are generated by the implant and to improve speech comprehension. In some subjects, this prerequisite cannot be measured using routine audiological tests. In this study, the feasibility of recording electrically evoked auditory brainstem responses (eABR) using a stimulating transtympanic electrode, placed on the round window niche, together with MED-EL clinical system is investigated. The results show that it is possible to record reproducible eABR measurements using PromBERA. The response was also confirmed with intraoperative eABR measurements that were stimulated using the implanted CI electrode array. Similarities between the intraoperative measurements and the preoperative recorded waveforms were observed. In summary, the integrity and excitability of the auditory nerve can be objectively measured using the PromBERA in subjects where standard clinical testing procedures are unable to provide the information required.

OBJECTIVES: The intracochlear electrocochleography (ECoG) could be recorded directly from the cochlear implant (CI) electrode in CI recipients with residual hearing. The primary objective of this study is to identify the most sensitive frequency to record cochlear microphonics (CM) in CI users with a wide degree of hearing abilities and deep electrode insertion. The secondary objective is to identify the optimum location within the cochlea to record intracochlear potentials. MATERIALS AND METHODS: CMs were recorded from the CI electrodes in eight females and eight males implanted with CIs Pulsar, Concerto, or Sonata, Med-El Corp. RESULTS: Among the tone pips of various frequencies, 1k or 500 Hz were the most sensitive for CI users. The most sensitive place in the cochlea to record the CM potentials depended on the tone frequency used. The deeper into the cochlea the mean maximum CM peak-to-peak amplitude was measured, the lower the stimulating tone frequency was. CONCLUSION: The most optimal recording parameters identified for intracochlear CM recording can be useful for intraoperative and postoperative monitoring of cochlear health in CI users with residual hearing.

[Objective]: To use an intracochlear test electrode to assess the integrity and the functionality of the auditory nerve in cochlear implant (CI) recipients and to compare electrical auditory brainstem responses (eABR) via the test electrode with the eABR responses with the CI., [Setting]: Otolaryngology department, tertiary referral hospital., [Patients]: Ten subjects (age at implantation 55 yr, range, 19–72) were subsequently implanted with a MED-EL CONCERTO CI on the side without any useful residual hearing., [Interventions]: Following identification of the round window (RW), the test electrode was inserted in the cochlea previous to cochlear implantation., [Main Outcome Measures]: To assess the quality of an eABR waveform, scoring criteria from Walton et al. (2008) were chosen. The waveforms in each session were classified by detecting waves III and V by the algorithm and visual assessment of the waveform. Speech performance was evaluated with monosyllables, disyllables, and sentence recognition tests., [Results]: It was possible to evoke electrical stimulation responses along with both the test electrode and the CI in all subjects. No significant differences in latencies or amplitudes after stimulation were found between the test electrode and the CI. All subjects obtained useful hearing with their CI and use their implants daily., [Conclusions]: The intracochlear test electrode may be suitable to test the integrity of the auditory nerve by recording eABR signals. This allows for further research on the status of the auditory nerve after tumor removal and correlation with auditory performance.

Recently, cochlear implant (CI) eligibility criteria have broadened to include individuals with partial deafness, a condition in which, prior to implantation, a significant amount of low-frequency hearing remains. Cochlear implantation aimed for hearing preservation in partial deafness has been recognized as a new method of partial deafness treatment. However, it is not only hearing preservation that has a great influence on the performance of such users; it is also the fitting of the audio processor consisting of acoustic and electric part. In this paper the authors review results of recent studies that underline the importance of correct fitting of the audio processor in order to achieve good benefits in Electric-Acoustic Stimulation (EAS).

Aim: The main goal of the present study was to assess the feasibility of using evoked stapedius reflex (eSR) and evoked compound action potential (eCAP) thresholds to create speech processor programs for children using Med-El Maestro software. The secondary goals were (1) to compare the eSR and eCAP thresholds recorded using charge units in experienced adults fitted with Med-El Pulsar CI100 cochlear implants with most comfortable loudness levels (MCLs) obtained for the apical, medial and basal electrodes, and (2) to compare eSR and eCAP thresholds for the apical, medial and basal electrodes between adults and children. Methods: Fourteen children and 16 adults participated in the study. eSR and eCAP thresholds were measured in both groups using the auditory nerve response telemetry algorithm, with MCL being behaviourally measured only in the adult group. Results: In the adult population, the correlation between eSR threshold and MCL was better for apical, medial and basal electrodes than that between eCAP threshold and MCL. There was no significant difference in the means obtained for eCAP and eSR thresholds in children and adults for any of the electrodes tested. This finding suggests that in children, the correlations between eCAP thresholds and MCL values, and those between eSR thresholds and MCL values are not lower than those generally found in adults. Conclusions: Although the eSR threshold is a better predictor of MCL values, both eSR and eCAP thresholds can be useful tools for assisting with map creation for children.

In cochlear implants each signal delivered to the cochlea can be considered as a ‘carrier’: the temporal fine structure TFS, which is determined by the dominant frequencies in the signal that fall ...

Biphasic electrical pulses are the standard stimulation pulses in current cochlear implants. In auditory brainstem recordings biphasic pulses generate a significant artifact that disrupts brainstem responses, which are magnitudes smaller. Triphasic pulses may minimize artifacts by restoring the neural membrane to its resting potential faster than biphasic pulses and make auditory brainstem responses detection easier. We compared biphasic pulses with triphasic and precision triphasic pulses to evoke brainstem responses in human subjects. For this purpose, electrically evoked brainstem response audiometry was performed in 10 (11 ears) cochlear implant patients. Artifacts and brainstem responses evoked by bi- and triphasic stimulation were analyzed. Artifact amplitude and decay time were related to pulse pattern shape, but application of averaging and alternation reduced the deterioration of electrically evoked brainstem responses independent of pulse pattern shape. Contrary to our expectations, biphasic pulses showed a higher detectability in comparison to triphasic pulse stimulation at the same stimulation amplitude.

Cochlear implant programming necessitates accurate setting of programming levels, including maximum stimulation levels, of all active electrodes. Frequently, clinical techniques are adequate for setting these levels; however, they are sometimes insufficient (e.g., very young children). In the Nucleus 24, several methods have been suggested for estimation of comfort levels (C levels) from neural response telemetry (NRT); however, many require co-application of clinical measurements. Data was obtained from 21 adult Nucleus 24 recipients to develop reliable predictions of C levels. Multiple regression analysis was performed on NRT threshold, slope of the NRT growth function, age, length of deafness, length of cochlear implant use and electrode impedance to examine predictive ability. Only the NRT threshold and slope of the growth function measures were significant predictors yielding R2 values from 0.391 to 0.769. Results demonstrated that these measures may provide an alternative means of estimating C levels when other clinical measures are unavailable.

Objectives: This study was designed to compare the incidence and nature of facial nerve stimulation (FNS) in patients receiving cochlear implants (CI) manufactured by Cochlear Corporation, Advanced Bionics Corporation, and MedEl. Study Design: Retrospective chart review at a tertiary referral center. Methods: The charts of 600 patients who received CIs from 1993 to 2003 with at least 1 year of follow-up were reviewed for significant FNS (FNS on at least 1 channel at functional stimulation levels). Data collected included age, sex, etiology of deafness, device type, electrode, FNS onset after initial stimulation, number and location of electrode contacts causing FNS, and loudness level at which FSN occurred. Nucleus straight and perimodiolar electrodes were also compared. Results: Thirty-nine of 600 (6.5%) patients had FNS on at least one channel, (MedEl 3 of 43 [7.0%], Nucleus 29 of 440 [6.6%], and Clarion 7 of 117 [6.0%]). The incidence of FNS in Nucleus perimodiolar electrodes (16 of 250 [6.4%]) was similar to straight electrodes (13 of 190 (6.8%]), as was the mean number of electrodes causing FNS per patient (11 vs. 12). However, straight electrodes caused stimulation at significantly softer perceived loudness levels than perimodiolar electrodes (P

In this article, we describe an efficient method for testing both auditory receptor and auditory nerve function in a single recording session. Auditory receptor function is tested in response to pure tone, tone burst and click acoustic stimuli (i.e. distortion products of otoacoustic emissions, DPOAE; and auditory-evoked brainstem responses, ABR). The function of the auditory neurons and nerve is measured in response to direct electric current stimulation (i.e. electrically evoked auditory brainstem responses, eABR). All measurements were obtained from anesthetized laboratory rats during single recording sessions using hardware and software stimulation and analysis programs developed by Intelligent Hearing Systems, Miami, FL.

Over the past two decades, cochlear implantation has become a widely accepted treatment of deafness in children. Over 20,000 children have received cochlear implants worldwide. Hearing, language and social development outcomes have been positive. We review current issues in cochlear implantation, candidacy, evaluation, surgery, habilitation, ethics and outcomes.

Objective The aim of this study was to assess the benefit of having preserved acoustic hearing in the implanted ear for speech recognition in complex listening environments. Design The present study included a within-subjects, repeated-measures design including 21 English-speaking and 17 Polish-speaking cochlear implant (CI) recipients with preserved acoustic hearing in the implanted ear. The patients were implanted with electrodes that varied in insertion depth from 10 to 31 mm. Mean preoperative low-frequency thresholds (average of 125, 250, and 500 Hz) in the implanted ear were 39.3 and 23.4 dB HL for the English- and Polish-speaking participants, respectively. In one condition, speech perception was assessed in an eight-loudspeaker environment in which the speech signals were presented from one loudspeaker and restaurant noise was presented from all loudspeakers. In another condition, the signals were presented in a simulation of a reverberant environment with a reverberation time of 0.6 sec. The response measures included speech reception thresholds (SRTs) and percent correct sentence understanding for two test conditions: CI plus low-frequency hearing in the contralateral ear (bimodal condition) and CI plus low-frequency hearing in both ears (best-aided condition). A subset of six English-speaking listeners were also assessed on measures of interaural time difference thresholds for a 250-Hz signal. Results Small, but significant, improvements in performance (1.7-2.1 dB and 6-10 percentage points) were found for the best-aided condition versus the bimodal condition. Postoperative thresholds in the implanted ear were correlated with the degree of electric and acoustic stimulation (EAS) benefit for speech recognition in diffuse noise. There was no reliable relationship among measures of audiometric threshold in the implanted ear nor elevation in threshold after surgery and improvement in speech understanding in reverberation. There was a significant correlation between interaural time difference threshold at 250 Hz and EAS-related benefit for the adaptive speech reception threshold. Conclusions The findings of this study suggest that (1) preserved low-frequency hearing improves speech understanding for CI recipients, (2) testing in complex listening environments, in which binaural timing cues differ for signal and noise, may best demonstrate the value of having two ears with low-frequency acoustic hearing, and (3) preservation of binaural timing cues, although poorer than observed for individuals with normal hearing, is possible after unilateral cochlear implantation with hearing preservation and is associated with EAS benefit. The results of this study demonstrate significant communicative benefit for hearing preservation in the implanted ear and provide support for the expansion of CI criteria to include individuals with low-frequency thresholds in even the normal to near-normal range.

This review covers the molecular mechanisms involved in hair cell and hearing losses which can result from trauma generated during the process of cochlear implantation and the contributions of both the intrinsic and extrinsic cell death signaling pathways in producing these trauma/inflammation induced losses. Application of soft surgical techniques to conserve hearing and protect auditory sensory cells during the process of cochlear implantation surgery and insertion of the electrode array during the process of cochlear implantation are reviewed and discussed. The role of drug therapy and mode of drug delivery for the conservation of a cochlear implant patient's residual hearing is presented and discussed.

(2010). Fitting of the Hearing System Affects Partial Deafness Cochlear Implant Performance. Cochlear Implants International: Vol. 11, Proceedings of the 9th European Symposium on Paediatric Cochlear Implantation, Warsaw, 2009, pp. 117-121.

Research into electric acoustic stimulation (EAS) indicates that performance improves when acoustic stimulation is added to electric stimulation in subjects with residual low-frequency acoustic hearin

Objectives: To compare speech test performance of adults with partial deafness cochlear implantation (PDCI) with that of adults with cochlear implant (CI). Based on the results, our objective is to determine the efficacy of the two applications of cochlear implantation, the first characterized by a shallow electrode insertion and preservation of low-frequency natural hearing for partial deafness, and the second characterized by a very deep electrode insertion used in subjects with severe to profound deafness. All the PDCI participants in this study were fitted with a recently upgraded DUET Hearing System from Med-El Corporation, Innsbruck, Austria. Study Design: This is a two-group comparison study. Eleven experienced PDCI adults and 22 postlingually deafened CI adults participated in this study. Subjects were implanted with either COMBI 40+ or PULSAR cochlear implant. Methods: Subjects were tested with monosyllable and sentence tests in Polish in quiet and under various signal-to-noise ratio (SNR) in the conditions of DUET only, CI only, DUET hearing aid (HA) only, and best aided (DUET plus contralateral hearing). CI subjects were tested with their CI. Results: PDCI subjects performed significantly better than CI subjects did. Speech tests demonstrated the best results in the conditions of best aided and DUET only. The poorest results were obtained in the condition DUET HA only. Results show a greater benefit for the PDCI group of subjects fitted with the DUET, compared to the CI alone group. Conclusions: The shallow electrode array insertion with preserved low-frequency hearing is a highly effective method for the treatment of partial deafness. The combination of HA and CI processor, i.e., the DUET, is beneficial in noise and in quiet.

HYPOTHESES 1) Hearing loss caused by electrode insertion trauma has both acute and delayed components; and 2) the delayed component of trauma-initiated hearing loss can be prevented by a direct delivery of a peptide inhibitor of the c-Jun N-terminal kinase cell death signal cascade, that is, D-JNKI-1, immediately after the electrode insertion within the cochlea. BACKGROUND Acute trauma to the macroscopic elements of the cochlea from electrode insertion is well known. The impact of trauma-induced oxidative stress within injured cochlear tissues and the efficacy of drugs (e.g., D-JNKI-1) to prevent apoptosis of damaged hair cells is not well defined. METHODS Hearing function was tested by pure-tone evoked auditory brainstem responses (ABRs) and distortion products of otoacoustic emissions (DPOAEs). D-JNKI-1 in artificial perilymph (AP) or AP alone was delivered into the scala tympani immediately after electrode trauma and for 7 days. Controls were nontreated contralateral and D-JNKI-1-treated ears without electrode insertion trauma. RESULTS There was no increase in the hearing thresholds of either the contralateral control ears or in the D-JNKI-1 without trauma animals. There was a progressive increase in ABR thresholds and decrease in DPOAE amplitudes after electrode insertion trauma in untreated and in AP-treated cochleae. Treatment with D-JNKI-1 prevented the progressive increase in ABR thresholds and decrease in DPOAE amplitudes that occur after electrode insertion trauma. CONCLUSION Hearing loss caused by cochlear implant electrode insertion trauma in guinea pigs has both acute and delayed components. The delayed component can be prevented by treating the cochlea with D-JNKI-1.

Problem: Electrode insertion trauma can cause loss of hearing due to the apoptosis of injured cochlear sensory cells. Methods: Hearing acuity was evaluated in rats before and after electrode insertion trauma both with and without scala tympani infusion of D-JNKI-1 peptide. Hearing was measured pre-trauma and for 7 days following trauma. Objective measurements were: distortion products of otoacoustic emissions (DPOAE), tone bursts (8–32kHz), and click-evoked auditory brain stem responses (ABRs) recorded using Intelligent Hearing Systems hardware and software. Results: Electrode insertion trauma consisted of insertion and withdrawal of a ball electrode through a round window membrane excision. Drug delivery consisted of infusion of D-JNKI-1 peptide through a micro-catheter inserted through the RWM. The otoprotective drug was a peptide inhibitor of c-Jun N-Terminal Kinase, an apoptosis signal molecule. The DPOAE threshold for pre-surgical rats was 25 dB SPL; ABR thresholds varied from 10 to 45 dB SPL depending on the frequency, and click-evoked thresholds varied from 30 to 40 dB SPL. There were progressive increases in thresholds and decreases in amplitudes of the ABRs following electrode insertion trauma. The amplitude of the DPOAEs in the electrode trauma cochleae also showed progressive decreases. For untreated, control cochleae there were no significant changes in either the DPOAE or ABR thresholds following electrode insertion into contra-lateral experimental cochleae. The efficacy of the otoprotective drug will be discussed. Conclusion: These results present an effective method for documenting progressive post-implantation trauma-generated hearing loss and suggest a novel therapeutic approach for preventing post-electrode insertion complications related to apoptosis. Significance: This study provides a better understanding of the hearing loss that occurs in response to cochlear implant electrode insertion trauma and may lead to the development of a novel therapy. Support: None reported.

The purpose of this study was to gain greater understanding of compound action potential (CAP) specific characteristics including: slope of the growth function, P1-N1 amplitude, threshold and latencies of P1 and N1 measured in cochlear implant users. Experienced adult subjects underwent behavioral threshold (T) measurement and electrically elicited stapedial reflex (eSR) recording, followed by CAP measurements on six selected electrodes. Based on the electrically elicited stapedial reflex threshold (eSRT), maximum stimulation level for each measured electrode was set. Relationships among the three thresholds of the above measures and maximum CAP P1-N1 amplitude and slope of the growth function were statistically evaluated for each measured electrode. Threshold of the CAP response showed relationships of similar strength with eSRT and T (r=0.69 and 0.61, respectively). For both slope of the growth function and CAP P1-N1 amplitude, a statistically significant relationship with cochlear place was found. Both specific characteristics of CAP measurement for the most apical electrodes were roughly double those for the most basal electrode (alpha=0.05). This may be partially explained by cochlear anatomy and is consistent with prior mammalian and human studies showing increasing density and survival of spiral ganglion cells in the regions corresponding to intracochlear electrode placement from basal to apical electrodes (90-360 degrees ).

This study investigates the role of hearing in vowel productions of postlingually deafened cochlear implant (CI) users. Based on the hypothesis that competing demands of intelligibility and economy of effort influence vowel production, we predicted that speakers of a language with a more crowded vowel space, such as American English, would show an increase in average vowel spacing (AVS the average inter‐vowel distance in the F1‐F2 plane) with the provision of hearing from a CI; whereas speakers of a language with fewer vowels, such as Spanish, would not. Results of a preliminary on–off study supported the hypothesis: with hearing from a CI, 7 English‐speaking CI users all increased AVS; however, among 7 Spanish speakers, some increased AVS and some reduced it. The current study is exploring these findings further with new groups of CI users and normal‐hearing speakers of English and Spanish and an elaborated paradigm that includes different speaking rates and comparisons between pre‐implant and post‐impla...

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions (clear, normal, and fast), and two feedback conditions after implantation (implant processor turned on and off). Ten normal-hearing controls were also recorded once. Vowel contrasts in the formant space (expressed in mels) were larger in the clear than in the fast condition, both for controls and for implant users at all three time samples. Implant users also produced differences in duration between clear and fast conditions that were in the range of those obtained from the controls. In agreement with prior work, the implant users had contrast values lower than did the controls. The implant users' contrasts were larger with hearing on than off and improved from one month to one year postimplant. Because the controls and implant users responded similarly to a change in speaking condition, it is inferred that auditory feedback, although demonstrably important for maintaining normative values of vowel contrasts, is not needed to maintain the distinctiveness of those contrasts in different speaking conditions.