Electrically evoked compound action potentials are different depending on the site of cochlear stimulation.

One of the many parameters that can affect cochlear implant (CI) users' performance is the site of presentation of electrical stimulation, from the CI, to the auditory nerve. Evoked compound action potential (ECAP) measurements are commonly used to verify nerve function by stimulating one electrode contact in the cochlea and recording the resulting action potentials on the other contacts of the electrode array. The present study aimed to determine if the ECAP amplitude differs between the apical, middle, and basal region of the cochlea, if double peak potentials were more likely in the apex than the basal region of the cochlea, and if there were differences in the ECAP threshold and recovery function across the cochlea. ECAP measurements were performed in the apical, middle, and basal region of the cochlea at fixed sites of stimulation with varying recording electrodes. One hundred and forty one adult subjects with severe to profound sensorineural hearing loss fitted with a Standard or FLEXSOFT electrode were included in this study. ECAP responses were captured using MAESTRO System Software (MED-EL). The ECAP amplitude, threshold, and slope were determined using amplitude growth sequences. The 50% recovery rate was assessed using independent single sequences that have two stimulation pulses (a masker and a probe pulse) separated by a variable inter-pulse interval. For all recordings, ECAP peaks were annotated semi-automatically. ECAP amplitudes were greater upon stimulation of the apical region compared to the basal region of the cochlea. ECAP slopes were steeper in the apical region compared to the basal region of the cochlea and ECAP thresholds were lower in the middle region compared to the basal region of the cochlea. The incidence of double peaks was greater upon stimulation of the apical region compared to the basal region of the cochlea. This data indicates that the site and intensity of cochlear stimulation affect ECAP properties.

Sound quality in adult cochlear implant recipients using the HISQUI19.

CONCLUSION: On average, adult CI recipients report a moderate sound quality using the Dutch version of the HISQUI19 questionnaire. These results are correlated with their age, speech perception scores, CI aided hearing thresholds, and the SSQ5 and the APHAB questionnaire. BACKGROUND: The general aim of the study was to assess sound quality in adult cochlear implant (CI) recipients and to link these findings to other patients reported outcome measures (PROM) and subject characteristics. Therefore, the Hearing Implant Sound Quality Index (HISQUI19), which was translated into Dutch, was used. This user-friendly instrument quantifies sound quality experienced by hearing implant users. METHODS: The Dutch version of the original German HISQUI19 was obtained by the process of translation and back-translation. The HISQUI19 was assessed in 65 experienced adult CI users at the Ear, Nose, and Throat (ENT) department of the Antwerp University Hospital to assess a sound quality profile of experiences adult CI recipients. Therefore, descriptive statistics were used to summarize the mean, standard deviation, and ceiling or floor effects of the total HISQUI19 scores in a CI population. Spearman correlations between the HISQUI19 scores and objective audiological measures and other PROM were investigated (APHAB and SSQ5 questionnaire). RESULTS: The mean HISQUI19 score of the Dutch version in adult CI recipients was 64.9 (SD = 20.8), which corresponds to moderate sound quality. The psychometric characters of the Dutch questionnaire are similar to the characters of the original HISQUI19 questionnaire, emphasizing good internal consistency (α = 0.93) and construct validity. Moderate correlation was found with speech perception in quiet (r = 0.36, p < 0.01), speech perception in noise (r = 0.29, p < 0.05), CI aided Pure Tone Average (PTA0.5, 1, 2 and 4 kHz) of the subjects (r = 0.34, p < 0.01), and the age of the subject (r = 0.38, p < 0.01). Gender did not influence the experienced sound quality significantly. Furthermore, the relation to other questionnaires was found to be significantly strong (SSQ5: r = 0.68 and the APHAB: r = 0.64; p < 0.01).

Improved speech reception and sound quality with the DUET2 audio processor for electric acoustic stimulation.

CONCLUSION: The results show that the DUET2 offers users speech perception that is equivalent to or better than the DUET. Moreover, the DUET2 offers subjective benefits above those provided by the DUET. BACKGROUND: The DUET is a combination of hearing aid and CI in one device for electric acoustic stimulation. Since its introduction: a second generation, the DUET2, has been developed. This study aimed to investigate the benefits of the DUET2 compared to the DUET. METHODS: Speech reception was determined in quiet and in noise. The sound quality of speech and music was rated using a visual analogue scale. Test intervals were at upgrade and at 3 and 6 months after upgrade. RESULTS: Speech reception in quiet and in noise was significantly better than with the DUET after 6 months. For sentence reception in quiet, the SRT with the DUET2 did not change significantly between test intervals. Sentence reception in noise with the DUET2 improved significantly between 3 and 6 months and upgrade and 6 months. After 6 months, speech reception in quiet and in noise with the DUET2 was significantly better than with the DUET. Subjects rated the sound quality of speech and of music with the DUET2 significantly better than with the DUET.

Binaural auditory outcomes in patients with postlingual profound unilateral hearing loss: 3 years after cochlear implantation.

The value of cochlear implants (CI) in patients with profound unilateral hearing loss (UHL) and tinnitus has recently been investigated. The authors previously demonstrated the feasibility of CI in a 12- month outcome study in a prospective UHL cohort. The aim of this study was to investigate the binaural auditory outcomes in this cohort 36 months after CI surgery. The 36-month outcome was evaluated in 22 CI users with postlingual UHL and severe tinnitus. Twelve subjects had contralateral normal hearing (single-sided deafness - SSD group) and 10 subjects had a contralateral, mild to moderate hearing loss and used a hearing aid (asymmetric hearing loss - AHL group). Speech perception in noise was assessed in two listening conditions: the CIoff and the CIon condition. The binaural summation effect (S0N0), binaural squelch effect (S0NCI) and the combined head shadow effect (SCIN0) were investigated. Subjective benefit in daily life was assessed by means of the Speech, Spatial and Qualities of Hearing Scale (SSQ). At 36 months, a significant binaural summation effect was observed for the study cohort (2.00, SD 3.82 dB; p < 0.01) and for the AHL subgroup (3.34, SD 5.31 dB; p < 0.05). This binaural effect was not significant 12 months after CI surgery. A binaural squelch effect was significant for the AHL subgroup at 12 months (2.00, SD 4.38 dB; p < 0.05). A significant combined head shadow and squelch effect was also noted in the spatial configuration SCIN0 for the study cohort (4.00, SD 5.89 dB; p < 0.01) and for the AHL subgroup (5.67, SD 6.66 dB; p < 0.05). The SSQ data show that the perceived benefit in daily life after CI surgery remains stable up to 36 months at CIon. CI can significantly improve speech perception in noise in patients with UHL. The positive effects of CIon speech perception in noise increase over time up to 36 months after CI surgery. Improved subjective benefit in daily life was also shown to be sustained in these patients.

Frequency-place map for electrical stimulation in cochlear implants: Change over time.

The relationship between the place of electrical stimulation from a cochlear implant and the corresponding perceived pitch remains uncertain. Previous studies have estimated what the pitch corresponding to a particular location should be. However, perceptual verification is difficult because a subject needs both a cochlear implant and sufficient residual hearing to reliably compare electric and acoustic pitches. Additional complications can arise from the possibility that the pitch corresponding to an electrode may change as the auditory system adapts to a sound processor. In the following experiment, five subjects with normal or near-to-normal hearing in one ear and a cochlear implant with a long electrode array in the other ear were studied. Pitch matches were made between single electrode pulse trains and acoustic tones before activation of the speech processor to gain an estimate of the pitch provided by electrical stimulation at a given insertion angle without the influence of exposure to a sound processor. The pitch matches were repeated after 1, 3, 6, and 12 months of experience with the sound processor to evaluate the effect of adaptation over time. Pre-activation pitch matches were lower than would be estimated by a spiral ganglion pitch map. Deviations were largest for stimulation below 240° degrees and smallest above 480°. With experience, pitch matches shifted towards the frequency-to-electrode allocation. However, no statistically significant pitch shifts were observed over time. The likely explanation for the lack of pitch change is that the frequency-to-electrode allocations for the long electrode arrays were already similar to the pre-activation pitch matches. Minimal place pitch shifts over time suggest a minimal amount of perceptual remapping needed for the integration of electric and acoustic stimuli, which may contribute to shorter times to asymptotic performance.

A Retrospective Multicenter Study Comparing Speech Perception Outcomes for Bilateral Implantation and Bimodal Rehabilitation.

OBJECTIVES: To compare speech perception outcomes between bilateral implantation (cochlear implants [CIs]) and bimodal rehabilitation (one CI on one side plus one hearing aid [HA] on the other side) and to explore the clinical factors that may cause asymmetric performances in speech intelligibility between the two ears in case of bilateral implantation. DESIGN: Retrospective data from 2247 patients implanted since 2003 in 15 international centers were collected. Intelligibility scores, measured in quiet and in noise, were converted into percentile ranks to remove differences between centers. The influence of the listening mode among three independent groups, one CI alone (n = 1572), bimodal listening (CI/HA, n = 589), and bilateral CIs (CI/CI, n = 86), was compared in an analysis taking into account the influence of other factors such as duration of profound hearing loss, age, etiology, and duration of CI experience. No within-subject comparison (i.e., monitoring outcome modifications in CI/HA subjects becoming CI/CI) was possible from this dataset. Further analyses were conducted on the CI/CI subgroup to investigate a number of factors, such as implantation side, duration of hearing loss, amount of residual hearing, and use of HAs that may explain asymmetric performances of this subgroup. RESULTS: Intelligibility ranked scores in quiet and in noise were significantly greater with both CI/CI and CI/HA than with a CI-alone group, and improvement with CI/CI (+11% and +16% in quiet and in noise, respectively) was significantly better than with CI/HA (+6% and +9% in quiet and in noise, respectively). From the CI/HA group, only subjects with ranked preoperative aided speech scores >60% performed as well as CI/CI participants. Furthermore, CI/CI subjects displayed significantly lower preoperative aided speech scores on average compared with that displayed by CI/HA subjects. Routine clinical data available from the present database did not explain the asymmetrical results of bilateral implantation. CONCLUSIONS: This retrospective study, based on basic speech audiometry (no lateralization cues), indicates that, on average, a second CI is likely to provide slightly better postoperative speech outcome than an additional HA for people with very low preoperative performance. These results may be taken into consideration to refine surgical indications for CIs.

Long-term improvement of speech perception with the fine structure processing coding strategy in cochlear implants.

AIMS: To investigate the long-term effects of the fine structure processing (FSP) coding strategy on speech perception in noise and quality of life in experienced cochlear implant (CI) users. METHODS: In a prospective comparative clinical trial, 32 experienced postlingually deafened CI recipients were upgraded from the Tempo+ to the Opus 2 audio processor, implementing FSP in one group and high-definition continuous interleaved sampling (HDCIS) coding strategy in another group with identical frequency ranges. Speech perception in noise testing and the Speech, Spatial and Qualities (SSQ) questionnaire were administered at 0, 6, 12 and 24 months after the upgrade. RESULTS: FSP yielded significant long-term improvement of speech perception in noise of in total 13.2 dB from 16.2 dB SNR at the upgrade to 3.0 dB SNR after 24 months of FSP experience. No significant improvement of speech perception in noise over time was measured for the HDCIS group. With the SSQ questionnaire, a significant benefit of the FSP coding strategy was observed. CONCLUSIONS: The FSP coding strategy as implemented in the Med-EL Opus 2 audio processor improves speech perception in noise. This beneficial effect of FSP on speech perception in noise is not immediate but is significant after 12 months and further improves up to 24 months after implementation of FSP.

Tinnitus in a single-sided deaf ear reduces speech reception in the nontinnitus ear.

BACKGROUND: The influence of tinnitus on speech reception is under debate. A few previous studies addressed this issue and compared speech reception in groups with and without tinnitus, with tinnitus arising in both ears or in the same test ear. Recently, we demonstrated that loudness of tinnitus in single-sided deafness (SSD) could be reduced dramatically by implanting and activating a cochlear implant (CI). PURPOSE: The aim of the study was to evaluate whether changing the level of tinnitus in the SSD ear by disenabling or enabling the CI changes the speech reception in noise in the non-tinnitus ear. METHODS AND PATIENTS: Fifteen CI users (MED-EL multichannel) with SSD and incapacitating tinnitus participated. They had an initial score of 6 or greater out of 10 on the Visual Analogue Scale (VAS) and an average total score of 58.05 (standard deviation [SD], 13.68) on the Tinnitus Questionnaire. The outcome measure, speech reception threshold (SRT) in noise using an adaptive procedure was measured in the nontinnitus ear using insert earphones. The measurements were performed with a high tinnitus level and a low tinnitus level in the SSD ear, realized by switching the CI off or on. Tinnitus loudness was assessed on a VAS, and tinnitus loudness was also matched using an audiometer. RESULTS: Speech reception in noise is significantly worse in case of high tinnitus loudness. The mean difference in SRT in the nontinnitus ear between the 2 conditions (SRTCI off-SRTCI on) of the 15 subjects was 1.98 dB SNR (SD, 3.01 dB SNR). The mean tinnitus loudness on the VAS was 7.2 (SD, 2.6) in the CI-off condition. In the CI-on condition, the mean VAS score significantly declined to 3.4 (SD, 2.5). Also, the tinnitus loudness match improved from 22 dB SL (SD, 14.4 dB SL) to 10 dB SL (SD, 10.1 dB SL) in the CI-on condition. CONCLUSION: Unilateral tinnitus can significantly decrease speech reception in noise in the nontinnitus ear.

Factors affecting auditory performance of postlinguistically deaf adults using cochlear implants: an update with 2251 patients.

OBJECTIVE: To update a 15-year-old study of 800 postlinguistically deaf adult patients showing how duration of severe to profound hearing loss, age at cochlear implantation (CI), age at onset of severe to profound hearing loss, etiology and CI experience affected CI outcome. STUDY DESIGN: Retrospective multicenter study. METHODS: Data from 2251 adult patients implanted since 2003 in 15 international centers were collected and speech scores in quiet were converted to percentile ranks to remove differences between centers. RESULTS: The negative effect of long duration of severe to profound hearing loss was less important in the new data than in 1996; the effects of age at CI and age at onset of severe to profound hearing loss were delayed until older ages; etiology had a smaller effect, and the effect of CI experience was greater with a steeper learning curve. Patients with longer durations of severe to profound hearing loss were less likely to improve with CI experience than patients with shorter duration of severe to profound hearing loss. CONCLUSIONS: The factors that were relevant in 1996 were still relevant in 2011, although their relative importance had changed. Relaxed patient selection criteria, improved clinical management of hearing loss, modifications of surgical practice, and improved devices may explain the differences.

Pre-, per- and postoperative factors affecting performance of postlinguistically deaf adults using cochlear implants: a new conceptual model over time.

OBJECTIVE: To test the influence of multiple factors on cochlear implant (CI) speech performance in quiet and in noise for postlinguistically deaf adults, and to design a model of predicted auditory performance with a CI as a function of the significant factors. STUDY DESIGN: Retrospective multi-centre study. METHODS: Data from 2251 patients implanted since 2003 in 15 international centres were collected. Speech scores in quiet and in noise were converted into percentile ranks to remove differences between centres. The influence of 15 pre-, per- and postoperative factors, such as the duration of moderate hearing loss (mHL), the surgical approach (cochleostomy or round window approach), the angle of insertion, the percentage of active electrodes, and the brand of device were tested. The usual factors, duration of profound HL (pHL), age, etiology, duration of CI experience, that are already known to have an influence, were included in the statistical analyses. RESULTS: The significant factors were: the pure tone average threshold of the better ear, the brand of device, the percentage of active electrodes, the use of hearing aids (HAs) during the period of pHL, and the duration of mHL. CONCLUSIONS: A new model was designed showing a decrease of performance that started during the period of mHL, and became faster during the period of pHL. The use of bilateral HAs slowed down the related central reorganization that is the likely cause of the decreased performance.

Prevalence of leisure noise-induced tinnitus and the attitude toward noise in university students.

BACKGROUND: Adolescents and young adults often are exposed to potentially damaging loud music during leisure activities. As a consequence, more and more young adults suffer from tinnitus, hearing loss, and hyperacusis. The present study provides prevalence numbers for noise-induced tinnitus (NIT) in this group, the attitude toward loud music, and the factors influencing the use of hearing protection (HP). METHOD: A questionnaire was undertaken to evaluate the influence of permanent/transient tinnitus after loud music, the attitudes toward noise, influence of peers, and the ability to manipulate HP on the use of HP. The questionnaire was completed by 145 university students. RESULTS: Approximately 89.5% of the students had experienced transient tinnitus after loud music exposure. The prevalence of transient NIT was higher in female subjects compared with male students. Permanent NIT was experienced by 14.8%. Nevertheless, few respondents were worried, and the degree of HP use was low (11%). However, the presence of permanent tinnitus was a motivation for HP use. Most respondents held a neutral to positive attitude (i.e., pronoise) toward loud music and were not fully aware of the risks of too much noise exposure. CONCLUSION: NIT is a common phenomenon among young adults. The lack of knowledge in young adults and the underuse of HP in leisure activities provide useful information to refine preventive measures in the future.

Assessment of the subjective benefit of electric acoustic stimulation with the abbreviated profile of hearing aid benefit.

CONCLUSION: This study demonstrates that electric-acoustic stimulation (EAS) significantly decreases the subjective impairment in speech perception. OBJECTIVES: To assess the subjective benefit of EAS over the first 12 months after EAS fitting using the Abbreviated Profile of Hearing Aid Benefit (APHAB). METHOD: Twenty-three EAS users, implanted with either the PULSAR(CI)(100) FLEX(EAS) provided with the DUET EAS processor or the COMBI40+ Medium provided with the TEMPO+ speech processor, were included. Electric stimulation was activated about 1 month postoperatively; ipsilateral acoustic stimulation was added 2 months thereafter. EAS benefit was measured preoperatively with only a hearing aid and postoperatively at EAS fitting and then 3, 6 and 12 months after EAS fitting using the APHAB. RESULTS: Subjects reported significant improvements in the global score with a mean decrease in impairment from 74% preoperatively to 45% after 3 months of EAS use. Furthermore, clinical relevance was demonstrated in multiple subscales between preoperative and first fitting reflecting a true benefit of EAS with a probability of 95%.

Combined electric acoustic stimulation with the PULSARCI(100) implant system using the FLEX(EAS) electrode array.

CONCLUSION: This study demonstrates that electric acoustic stimulation (EAS(®)) using the FLEX(EAS) electrode is a successful treatment method for preservation and stability of low frequency hearing, and results in significant improvements in speech perception. OBJECTIVES: Low frequency hearing preservation and stability following EAS surgery with the MED-EL PULSARCI(100) implant using the FLEX(EAS) electrode and a combined processor in a multicentre setting, and the efficacy and benefits of EAS over time were evaluated. METHODS: Eighteen subjects with normal to moderate hearing loss in the low frequencies and severe to profound hearing loss in the high frequencies were implanted with the FLEX(EAS) electrode. Implantation was performed by different surgeons at three participating centres using either the cochleostomy or the round window approach. Preoperatively, hearing was measured; a battery of speech perception tests and the subjective benefit questionnaire were administered. These tests were subsequently repeated: first at EAS fitting, which was due 3 months after surgery, and then again 3, 6 and 12 months after EAS fitting. RESULTS: Hearing could be preserved in all subjects. Speech understanding showed significant improvement in all tests over time with the EAS condition outperforming the cochlear implant-only condition at all intervals. These considerable effects were also reflected in the subjective benefit outcome.

Electric acoustic stimulation: a new era in prosthetic hearing rehabilitation.

Hearing preservation after cochlear implantation and combined electric acoustic stimulation (EAS) in the same ear has reduced the gap between prosthetic hearing rehabilitation with hearing aids and cochlear implants. This has increased the possibility of successful hearing rehabilitation for patients. This paper describes the history of hearing preservation after cochlear implantation. Indications and criteria for combined electric acoustic stimulation are described, and hearing preservation surgery and outcomes achieved with combined EAS are discussed. EAS has led to a new era in prosthetic hearing rehabilitation providing new understanding of basic physiological, psychoacoustic and medical aspects of the inner ear.

Bilateral electric acoustic stimulation: a comparison of partial and deep cochlear electrode insertion. A longitudinal case study.

BACKGROUND/AIMS: A patient with bilateral severe, sloping, high-frequency hearing loss was treated with sequential bilateral electric acoustic stimulation (EAS) using the MED-EL Duet EAS cochlear implant. On one side, a partial 18-mm insertion of the electrode array (M-type) in the cochlea was performed. The contralateral side was implanted 39 months later with a deep 30-mm insertion of the electrode array (FLEX(soft) type). The aims were to assess whether low-frequency hearing could be preserved after deep electrode insertion, as well as to assess the benefit of bilateral EAS surgery compared to monaural EAS. METHODS: Hearing thresholds and speech recognition outcomes were measured preoperatively and up to 48 months postoperatively. Outcomes from the partial and deep insertion side are compared. The benefit of EAS in daily life was assessed with the Abbreviated Profile of Hearing Aid Benefit questionnaire. Benefits of bilateral EAS were calculated from speech reception thresholds measured using the LINT speech-in-noise number test. Speech was always presented from the front. Noise was either presented from the front, from the left side, or from the right side. Each condition was measured for unilateral and bilateral EAS use. RESULTS: Partial as well as deep insertion of the electrode array resulted in hearing preservation and significant speech recognition in this particular case. Both EAS devices provided more than 80% speech recognition in noise at a 10-dB signal-to-noise ratio. Bilateral EAS was beneficial for speech reception in noise compared to monaural EAS. A head shadow effect of 3.4 dB, binaural squelch effect of 1.2 dB and binaural summation effect of 0.5 dB were measured. CONCLUSION: Hearing preservation is also possible after cochlear implantation using a FLEX(soft) electrode array with a near-full insertion (30 mm) into the cochlea. Bilateral EAS was successfully implemented in this patient providing better speech recognition compared to monaural EAS.