Changes over time in the psycho-electric parameters in children with cochlear implants

Development of Custom Sound® Pro software utilising big data and its clinical evaluation

OBJECTIVES

To inform and optimise a cochlear implant (CI) fitting software design through an analysis of big data to define array-specific comfort (C) level profiles, frequently-used MAP parameters, and the minimum number of Neural Response Telemetry thresholds (tNRT) needed to create an accurate profile. To evaluate the software's ease of use and completion time for AutoNRT®s.

DESIGN

MAPs analysis. Clinical study evaluating software use in creating MAPs, addressing sound-quality issues and setting patient goals.

STUDY SAMPLE

MAPs (N = 39,885); CI recipients (N = 47) and clinicians (N = 19).

RESULTS

Distinct C-level profiles were observed for lateral-wall, contour, and slim-modiolar electrode arrays. Default settings were used for most MAP parameters (13/16) except for Pulse Width, Rate, and Maxima. Nine tNRT measurements were required for an accurate C-level profile. Measurement-time of nine tNRTs via the new algorithm was comparable to five tNRTs using the previous algorithm. Nearly all (99%) clinical tasks were completed by clinicians with the first use of the software. Most CI recipients (79.5%) rated goal-setting as valuable.

CONCLUSION

Custom Sound Pro fitting software developed based on big data analysis incorporates a guided fitting workflow and expected fitting ranges. It helps to improve clinical efficiency, is easy to use and supports patient-centred care.

Semantic processing in children with Cochlear Implants: A review of current N400 studies and recommendations for future research

Deaf and hard of hearing children with cochlear implants (CI) often display impaired spoken language skills. While a large number of studies investigated brain responses to sounds in this population, relatively few focused on semantic processing. Here we summarize and discuss findings in four studies of the N400, a cortical response that reflects semantic processing, in children with CI. A study with auditory target stimuli found N400 effects at delayed latencies at 12 months after implantation, but at 18 and 24 months after implantation effects had typical latencies. In studies with visual target stimuli N400 effects were larger than or similar to controls in children with CI, despite lower semantic abilities. We propose that in children with CI, the observed large N400 effect reflects a stronger reliance on top-down predictions, relative to bottom-up language processing. Recent behavioral studies of children and adults with CI suggest that top-down processing is a common compensatory strategy, but with distinct limitations such as being effortful. A majority of the studies have small sample sizes (N < 20), and only responses to image targets were studied repeatedly in similar paradigms. This precludes strong conclusions. We give suggestions for future research and ways to overcome the scarcity of participants, including extending research to children with conventional hearing aids, an understudied group.

Comparisons of electrophysiological and psychophysical fitting methods for cochlear implants

OBJECTIVE

This study compared two different versions of an electrophysiology-based software-guided cochlear implant fitting method with a procedure employing standard clinical software. The two versions used electrically evoked compound action potential (ECAP) thresholds for either five or all twenty-two electrodes to determine sound processor stimulation level profiles. Objective and subjective performance results were compared between software-guided and clinical fittings.

DESIGN

Prospective, double-blind, single-subject repeated-measures with permuted ABCA sequences.

STUDY SAMPLE

48 post linguistically deafened adults with ≤15 years of severe-to-profound deafness who were newly unilaterally implanted with a Nucleus device.

RESULTS

Speech recognition in noise and quiet was not significantly different between software- guided and standard methods, but there was a visit/learning-effect. However, the 5-electrode method gave scores on the SSQ speech subscale 0.5 points lower than the standard method. Clinicians judged usability for all methods as acceptable, as did subjects for comfort. Analysis of stimulation levels and ECAP thresholds suggested that the 5-electrode method could be refined.

CONCLUSIONS

Speech recognition was not inferior using either version of the electrophysiology-based software-guided fitting method compared with the standard method. Subject-reported speech perception was slightly inferior with the five-electrode method. Software-guided methods saved about 10 min of clinician's time versus standard fittings.

Electrical dynamic range is only weakly associated with auditory performance and speech recognition in long-term users of cochlear implants

OBJECTIVE

The electrical dynamic range (EDR) has been suggested to be related to auditory performance in cochlear implant (CI) users. However, few reports have evaluated postlingual CI users who have used CIs for long periods in comparison with prelingual CI users. Here, we evaluated auditory perception and speech performance in terms of the EDR in long-term CI users. The EDR, and auditory and speech performances, were compared between pre- and post-lingual CI users.

METHODS

We enrolled all patients who received CIs from April 2000 to December 2010 at Seoul National University Hospital, and who had ≥5 years of experience with CIs. The EDRs affording subjective responses at the threshold level (T-level) and comfortable level (C-level) were analyzed in terms of their relationships with pure tone audiometry levels, speech evaluation scores, including those on the Phonetically Balanced (PB) Word List test, vowel and consonant tests, a sentence test, and the Korean version of the Central Institute for the Deaf (K-CID) test; we also calculated Category in Auditory Performance (CAP) scores.

RESULTS

We found no significant difference in the average EDR, CAP, K-CID, PB word, consonant, or vowel scores between pre- and post-lingual CI users. The EDR was weakly associated with the PB word (P = 0.003, r = 0.462) and consonant scores (P = 0.005, r = 0.438). Other speech evaluations, such as the CAP, K-CID, and vowel scores, were not significantly associated with the EDR T-level. We found no association between pure tone thresholds at 0.5, 1, or 2 kHz, and the speech evaluation scores or EDRs of low-, middle-, or high-frequency channels.

CONCLUSIONS

The EDR was only weakly associated with speech performance, such as scores on consonant and PB word tests in long-term CI users, irrespective of pre- or post-lingual deafness status.

Temporal changes in impedance of implanted adults for various cochlear segments

Electrode impedance (EI) is the first objective assessment carried out during the surgical procedure and follow-up of cochlear implanted patients. This measure provides information on the integrity of electrodes and on the surrounding environment. It is one of the main factors responsible for energy consumption of the cochlear implant (CI). The aim of our study is to investigate changes over time in EI in adult recipients implanted with the perimodiolar array by comparing differences in various cochlear segments. In addition, we explore the relationship between these objective measures and subjective measures such as T-level and C-level. We studied 28 adult patients. Impedance values (IVs) were calculated in "common-ground" (CG) and in monopolar (M1+2) mode for electrode groups in basal middle and apical segments. We found significant decreases in IVs between activation and 1 month. We obtained higher values for basal impedance, whereas lower IVs were found for apical electrodes at all observation times. Statistical pairing over time between impedance and T/C values showed significant correlation for both global impedance (GI) and T-C levels at CG and M1+2 mode up to 6 months. Segregated statistical analysis also showed a significant and prolonged correlation of basal IVs and fitting parameters. The higher basal impedance over time can be explained by the higher proportion of newly formed tissue in this region. The linear correlation of impedances with the fitting parameters become not significant after 3/6 months for the apical and middle segments and remained significant only for the basal region over time. This behaviour underlines the importance of persistence in intra-cochlear factors in influencing fitting parameters in the basal segment.

Cochlear implant programming: a global survey on the state of the art

The programming of CIs is essential for good performance. However, no Good Clinical Practice guidelines exist. This paper reports on the results of an inventory of the current practice worldwide. A questionnaire was distributed to 47 CI centers. They follow 47600 recipients in 17 countries and 5 continents. The results were discussed during a debate. Sixty-two percent of the results were verified through individual interviews during the following months. Most centers (72%) participated in a cross-sectional study logging 5 consecutive fitting sessions in 5 different recipients. Data indicate that general practice starts with a single switch-on session, followed by three monthly sessions, three quarterly sessions, and then annual sessions, all containing one hour of programming and testing. The main focus lies on setting maximum and, to a lesser extent, minimum current levels per electrode. These levels are often determined on a few electrodes and then extrapolated. They are mainly based on subjective loudness perception by the CI user and, to a lesser extent, on pure tone and speech audiometry. Objective measures play a small role as indication of the global MAP profile. Other MAP parameters are rarely modified. Measurable targets are only defined for pure tone audiometry. Huge variation exists between centers on all aspects of the fitting practice.

MAP optimization as a predictor of cochlear implant outcomes in children with narrow internal auditory canal

OBJECTIVES

The purposes of this study were to investigate the auditory performance and MAP characteristics of implanted children with narrow internal auditory canal (IAC), and to examine the clinical usefulness of MAP optimization as a predictor of their cochlear implant (CI) outcomes by analyzing their auditory performance and habilitation methods in relation to MAP optimization.

METHODS

Eight children with narrow IAC who had used a CI over 3 years were included. We retrospectively examined their auditory performance and MAPs. Auditory performance was measured by the Categories of Auditory Performance (CAP) and monosyllabic word tests before and after implantation. The relationship between auditory performance and MAP parameters was explored, and their habilitation methods were analyzed.

RESULTS

Mean CAP scores improved from .25 preoperatively to 3.5 3 years postoperatively. Mean scores for monosyllabic word tests improved from 0% preoperatively to 27.8% 3 years postoperatively. The children used MAPs with a wider pulse width than the default setting. Four children using optimal MAPs achieved open-set speech perception, so were trained in the oral approach. The other four using suboptimal MAPs because of non-auditory stimulation achieved no open-set speech perception, so were trained in the total communication approach.

CONCLUSIONS

MAP optimization had a predictable value in determining the postoperative performance of children with narrow IAC who received a CI. The most suitable habilitation method can be determined early after implantation by identifying the presence of MAP optimization.

A longitudinal study of speech perception skills and device characteristics of adolescent cochlear implant users

BACKGROUND

For pediatric cochlear implant (CI) users, CI processor technology, map characteristics, and fitting strategies are known to have a substantial impact on speech perception scores at young ages. It is unknown whether these benefits continue over time as these children reach adolescence.

PURPOSE

To document changes in CI technology, map characteristics, and speech perception scores in children between elementary grades and high school, and to describe relations between map characteristics and speech perception scores over time.

RESEARCH DESIGN

A longitudinal design with participants 8-9-yr-old at session 1 and 15-18-yr-old at session 2.

STUDY SAMPLE

Participants were 82 adolescents with unilateral CIs, who are a subset of a larger longitudinal study. Mean age at implantation was 3.4 yr (range: 1.7-5.4), and mean duration of device use was 5.5 yr (range: 3.8-7.5) at session 1 and 13.3 yr (range: 10.9-15) at session 2.

DATA COLLECTION AND ANALYSIS

Speech perception tests at sessions 1 and 2 were the Lexical Neighborhood Test (LNT) presented at 70 dB SPL (LNT-70) and Bamford-Kowal-Bench sentences in quiet (BKB-Q) presented at 70 dB SPL. At session 2, the LNT was also administered at 50 dB SPL (LNT-50), and BKB sentences were administered in noise with a +10 dB SNR (BKB-N). CI processor technology type and CI map characteristics (coding strategy, number of electrodes, threshold levels, and comfort levels) were obtained at both sessions. Electrical dynamic range was computed, and descriptive statistics, correlations, and repeated-measures ANOVAs were employed.

RESULTS

Participants achieved significantly higher LNT and BKB scores, at 70 dB SPL, at ages 15-18 than at ages 8-9 yr. Forty-two participants had 1-3 electrodes either activated or deactivated in their map between test sessions, and 40 had no change in number of active electrodes (mean change: -0.5; range: -3 to +2). After conversion from arbitrary clinical map units to charge-per-phase in nanocoulombs (nC), no significant difference was found for T levels across time. Average comfort levels (C levels) decreased by 19 nC. Seventy-three participants (89%) upgraded their CI processor technology type. At both sessions, significant correlations were found between electrical dynamic range (EDR) and all speech perception measures except LNT-50 (r range: .31 to .47; p < 0.01). Similarly, significant correlations were also found between C levels and all speech perception measures (r range: .29 to .49; p < 0.01). At session 2, a significant correlation was found between processor technology type and the LNT-50 scores (r = .38; p < 0.01).

CONCLUSIONS

Significant improvement in speech scores was observed between elementary grades and high school for children who had used a CI since preschool. On average, T levels (nC) and electrode function remained stable for these long-term pediatric users. Analyses of maps did not allow for the determination of the exact cause of C level reductions, though power limitations in new processor systems and changes in perceived loudness over time are possible. Larger EDRs and higher C levels were associated with better speech scores. Newer speech processor technology was associated with better speech scores at a softer level.

Evaluation of simplified programs using the MED-EL C40+ cochlear implant

The present study evaluated the benefit possible from a cochlear implant (CI) using a simplified map (with a set of default parameters), rather than the conventional approach of producing a 'customized map' from electrode-specific psychophysical measures. Young children are sometimes initially provided with such maps and the aim was to gain an insight into what level of benefit they might provide. Maps with upper stimulation levels set equally across the array (i.e. 'flat' maps) were compared with normal 'customized' maps in established adult users of the MED-EL C40+ device. Speech discrimination was significantly poorer for the flat maps overall (mean of 72.7% for customized map, and 60.5% for flat map) and loudness balance estimates showed a range of degrees of imbalance. These results suggest that flat maps may provide paediatric CI users with useful levels of performance when psychophysical or objective measures cannot be obtained. The poorer performance with the flat map suggests that customized maps should be fit as soon as possible to provide paediatric patients with the maximum benefit of the CI device.

Cochlear implant recipients' hearing sensation as manifested by their maps during pregnancy and postpartum

OBJECTIVE

To investigate possible changes in hearing sensation as manifested in the maps' psychoacoustic parameters, threshold (T), and most comfortable (C/M) levels among cochlear implant (CI) female recipients during pregnancy and after delivery.

SETTING

University-affiliated tertiary referral center.

DESIGN

: Retrospective study.

METHOD

Two MedEl device and 3 Nucleus device users' medical records were reviewed for age at the time of implantation, cause of deafness, type of anesthesia used during delivery, and maps' parameters (T and C/M levels) during pregnancy and after childbirth.

RESULTS

Two CI recipients underwent uncomplicated cesarean deliveries under spinal anesthesia, and 3 others had natural delivery without anesthesia. There were no changes in map values during pregnancy, delivery, and the postpartum period in 4 of 5 CI recipients. Only 1 CI recipient showed significant increase in T levels that was resolved after she completed breastfeeding 3 months postdelivery.

CONCLUSION

The elevation in T levels might indicate that pregnancy and delivery can result in some temporary reversible changes in hearing sensation manifested by map levels of CI users.

Factors affecting perceptual thresholds in epiretinal prostheses

PURPOSE

The goal was to evaluate how perceptual thresholds are related to electrode impedance, electrode size, the distance of electrodes from the retinal surface, and retinal thickness in six subjects blind as a result of retinitis pigmentosa, who received epiretinal prostheses implanted monocularly as part of a U.S. Food and Drug Administration (FDA)-approved clinical trial.

METHODS

The implant consisted of an extraocular unit containing electronics for wireless data, power recovery, and generation of stimulus current, and an intraocular unit containing 16 platinum stimulating electrodes (260- or 520-microm diameter) arranged in a 4 x 4 pattern. The electrode array was held onto the retina by a small tack. Stimulation was controlled by a computer-based external system that allowed independent control over each electrode. Perceptual thresholds (the current necessary to see a percept on 79% of trials) and impedance were measured for each electrode on a biweekly basis. The distance of electrodes from the retinal surface and retinal thickness were measured by optical coherence tomography on a less regular basis.

RESULTS

Stimulation thresholds for detecting phosphenes correlated with the distance of the electrodes from the retinal surface, but not with electrode size, electrode impedance, or retinal thickness.

CONCLUSIONS

Maintaining close proximity between the electrode array and the retinal surface is critical in developing a successful retinal implant. With the development of chronic electrode arrays that are stable and flush on the retinal surface, it is likely that the influence of other factors such as electrode size, retinal degeneration, and subject age will become more apparent. (ClinicalTrials.gov number, NCT00279500.).

A longitudinal study of electrical stimulation levels and electrode impedance in children using the Clarion cochlear implant

CONCLUSIONS

Electrical stimulation levels and electrode impedance values (EIVs) in children using the Clarion cochlear implant (CI) programmed with CIS strategy stabilized after 3 months of implant use. The data presented here may be useful as a general guideline for the programming of infants and young children and may further be of help for the identification of patients who fall outside the "average" range.

OBJECTIVES

The purpose of the present study was to evaluate changes in electrical stimulation levels, i.e. threshold (T) levels, comfortable (M) levels, dynamic range (DR), and EIVs during the first 18 months of implant use, in children using the Clarion CI.

MATERIALS AND METHODS

The maps of 18 pre-lingual children (mean age at implantation 4.2 years; range 1-8), using the Enhanced Bipolar 1.2 or Bipolar standard electrode with the S-Series speech processor programmed with CIS strategy, were examined at five time points: connection, and 3, 6, 12, and 18 months post-initial stimulation. T levels, M levels, DR and EIVs were analyzed according to four cochlear segments: apical, apical-medial, medial-basal, and basal.

RESULTS

During the first 3 months of implant use T levels increased to some extent, whereas M levels and DR increased significantly. From 3 months and through the entire follow-up, T and M levels as well as DR were stable. EIVs of current carrying electrodes decreased significantly from connection to the 3-month visit; thereafter a stabilization of values was evident. Electrical stimulation levels and EIVs did not differ among the cochlear segments during the entire follow-up.

Electrical stimulation levels and electrode impedance values in children using the Med-El Combi 40+ cochlear implant: a one year follow-up

The present study was designed to follow changes in electrical stimulation levels and electrode impedance values (EIV) in children using the Med-El Combi 40+ cochlear implant (CI) during the first 12 months of implant use. The maps of 24 prelingually deaf children implanted at a mean age of 5.9 years (range 1-15.9 years) using the TEMPO+ speech processor programmed with CIS+ strategy were examined at five time points: initial stimulation, and 1, 3, 6, and 12 months post-initial stimulation. Most comfortable levels (M) and electrode impedance values (EIV) were analyzed according to three cochlear segments: apical, medial, and basal. Results indicated a significant increase in M levels until the 3-month time point, thereafter stabilization was evident. Furthermore, M levels in the apical segment were lower than those in the medial and basal segments. EIV decreased from initial stimulation to the 3-month time point and was then stable through the study follow up. Interestingly, the finding of higher EIV in the apical segment may be attributed to the physical characteristics of the Med-El electrode. In conclusion, the pattern of stabilization of M levels found in the present study is similar to that reported for children using other devices. The data presented here may be useful as a guideline for programming M levels and monitoring EIV in infants and young children. They may further help clinicians to identify those children that fall outside the 'typical' range.

Cochlear implantation in Waardenburg's syndrome

CONCLUSIONS

Children with Waardenburg's syndrome (WS) derive significant benefit from cochlear implantation (CI) and do so to an extent that is comparable to that of the general population of implanted children. Although we report on a relatively small cohort, our data are useful for counseling the parents of children with WS considering CI.

OBJECTIVE

To present our experience with CI in patients with WS.

MATERIAL AND METHODS

A retrospective record review was conducted for five children who underwent CI in our department between 1993 and 2004.

RESULTS

Children with WS comprised 1.9% of our entire pediatric CI population: four girls had a familial history of WS and the phenotype of WS Type I, and one boy met the criteria for WS Type II. They were all diagnosed as having bilateral profound sensorineural hearing loss 4-24 weeks after birth. Rehabilitation was initiated immediately and included bilateral fitting of hearing aids and intensive speech and language therapy. Otoscopic and temporal bone high-resolution CT findings were normal in all patients. At surgery, all children were found to have a patent cochlea, and the electrodes were implanted into the scala tympani without difficulty. After 1.3-10.2 years of implant use all children achieved open-set recognition of 2-syllable words, with an average score of 81%. Four of the 5 children achieved open-set recognition of monosyllabic words (average score 40%) and 3 achieved open-set recognition of words in sentences (average score 81%).