Early Cochlear Implantation Research Articles

A Comparative Evaluation of the Genetic Variant Spectrum in the USH2A Gene in Russian Patients with Isolated and Syndromic Forms of Retinitis Pigmentosa

Pathogenic variants in the USH2A gene are the primary cause of both non-syndromic autosomal recessive inherited retinitis pigmentosa (RP) and the syndromic form, characterized by retinal degeneration and sensorineural hearing loss. This study presents a comparative assessment of the genetic variant spectrum in the USH2A gene among Russian patients in two clinical groups. A retrospective analysis was conducted on massive parallel panel sequencing data from 2415 blood samples of unrelated patients suspected of having hereditary retinal diseases. The copy number of USH2A exons was determined using the quantitative MLPA method with the MRC-Holland SALSA MLPA kit. Biallelic pathogenic and likely pathogenic variants in the USH2A gene were identified in 69 patients (8.7%). In the group of patients with isolated hereditary RP (55 patients), the most frequent pathogenic variants were p.(Glu4445_Ser4449delinsAspLeu) (20.9%), p.(Trp3955*) (15.5%), and p.(Cys934Trp) (5.5%). In patients with the syndromic form (14 patients), the most frequent variants were p.(Trp3955*) (35.7%) and c.8682-9A>G (17.9%). It was found that patients with isolated vision impairment rarely had two “null” variants (17.8%), whereas this was common among patients with both hearing and vision impairment (71.4%) (p ≤ 0.05), explaining the severity of the disease and the earlier onset of clinical symptoms in the syndromic form of RP. Ten previously undescribed loss-of-function variants were identified. The estimated prevalence of USH2A-associated retinal dystrophy in Russia was 1.9 per 100,000 individuals. The obtained data on the differences in the spectra of genetic variants in the USH2A gene in the two studied groups highlight the importance of establishing genotype–phenotype correlations and predicting disease severity, aiming at potential early cochlear implantation and selection of target therapy.

Auditory Development of Young Children with Profound Hearing Loss, Cochlear Implants, and Congenital CMV Infection

Background/Objectives: The aim of this study was to assess auditory development in young children with profound hearing loss, cochlear implants (CIs), and congenital cytomegalovirus (cCMV) infection and to determine the effect of comorbidities on their development. Methods: The study group (cCMV group) consisted of 47 CI children—18 girls and 29 boys—who had been diagnosed as having prelingual hearing loss due to cCMV infection (with or without comorbidities); the mean age at CI activation was 15.2 months (range: 9.7–23.8; SD = 3.5). The reference group (no cCMV) consisted of 117 similar children (57 girls and 60 boys) who had profound sensorineural hearing loss not caused by cCMV infection; they had no comorbidities. The mean age at CI activation in the second group was 14.3 months (range: 7.9–23.5; SD = 4.0). Auditory development in all children was assessed with the LittlEARS Auditory Questionnaire (LEAQ) at CI activation and at about 1, 5, 9, 14, and 24 months of CI use. Results: The mean LEAQ total score increased over a similar time frame from 9.8 pts to 28.9 pts in the cCMV group without comorbidities, from 4.5 pts to 18.5 pts in the cCMV group with comorbidities, and from 9.2 to 31.6 pts in the reference group with no cCMV infection. Conclusions: Early cochlear implantation in children with sensorineural hearing loss due to congenital CMV infection and no comorbidities promotes their early auditory development in a similar way to children without cCMV infection.

Early cochlear implantation: exploring electrophysiological thresholds and their role in pre-behavioural recommendations.

Studies investigating the relationship between initial electrophysiological thresholds and subsequent behavioural hearing thresholds have demonstrated uncertainty as to whether initial results can provide an accurate estimation of an infant's functional hearing. This estimation must be accurate if a cochlear implant (CI) is to be considered before behavioural audiometry.This study aims to explore the variance between initial electrophysiological thresholds and subsequent behavioural hearing thresholds in infants to determine under which conditions electrophysiological results can be used to support a CI recommendation before behavioural audiology. This is a prospective cohort study of 63 infants with suspected severe to profound hearing loss, referred to the Cochlear Implant Clinic, Melbourne, before 12 months of age. The assessment protocol includes auditory brainstem response, auditory steady state response, tympanometry, and behavioural audiometry. For most infants undergoing CI candidacy evaluation, initial electrophysiological thresholds are an accurate reflection of their subsequent behavioural thresholds. An alternative CI candidacy pathway is recommended for infants who show profound sensorineural hearing loss on initial electrophysiological testing, in the absence of middle ear effusion, prematurity, or auditory neuropathy features, to provide CI recommendations before behavioural thresholds are obtained. This would lead to reduced delay to implantation and improved oral language outcomes.

Perception of voice cues and speech-in-speech by children with prelingual single-sided deafness and a cochlear implant

Voice cues, such as fundamental frequency (F0) and vocal tract length (VTL), help listeners identify the speaker's gender, perceive the linguistic and emotional prosody, and segregate competing talkers. Postlingually implanted adult cochlear implant (CI) users seem to have difficulty in perceiving and making use of voice cues, especially of VTL. Early implanted child CI users, in contrast, perceive and make use of both voice cues better than CI adults, and in patterns similar to their peers with normal hearing (NH).In our study, we investigated the perception and use of voice cues in children with single-sided deafness (SSD) who received their CI at an early age (SSD+CI), in an attempt to bridge the gap between these two groups. The SSD+CI children have access to bilateral auditory information and often receive their CI at an early age, similar to CI children. They may also have dominant acoustic representations, similar to CI adults who acquired hearing loss at a later age. As such, the current study aimed to investigate the perception and use of voice cues by a group of nine early-implanted children with prelingual SSD. The study consisted of three experiments: F0 and VTL discrimination, voice gender categorization, and speech-in-speech perception. In each experiment, the results of the SSD group are compared to children and adults with CIs (for their CI ear) and with typical hearing (for their NH ear).Overall, the SSD+CI children had poorer VTL detection thresholds with their CI compared to their NH ear, while their F0 perception was similar across ears. Detection thresholds for both F0 and VTL with their CI ear was comparable to those of bilaterally implanted CI children, suggesting that SSD+CI children do not only rely on their NH ear, but actually make use of their CI. SSD+CI children relied more heavily on F0 cues than on VTL cues for voice gender categorization, with cue weighting patterns comparable to those of CI adults. In contrast to CI children, the SSD+CI children showed limited speech perception benefit based on F0 and VTL differences between the target and masker speaker, which again corresponded to the results of CI adults. Altogether, the SSD+CI children make good use of their CI, despite a good-hearing ear, however, the perceptual patterns seem to fall in-between those of CI children and CI adults. Perhaps a combination of childhood neuroplasticity, limited experience with relying only on the CI, and a dominant acoustic representation of voice gender explain these results.

Close approximations to the sound of a cochlear implant.

Cochlear implant (CI) systems differ in terms of electrode design and signal processing. It is likely that patients fit with different implant systems will experience different percepts when presented speech via their implant. The sound quality of speech can be evaluated by asking single-sided-deaf (SSD) listeners fit with a cochlear implant (CI) to modify clean signals presented to their typically hearing ear to match the sound quality of signals presented to their CI ear. In this paper, we describe very close matches to CI sound quality, i.e., similarity ratings of 9.5 to 10 on a 10-point scale, by ten patients fit with a 28 mm electrode array and MED EL signal processing. The modifications required to make close approximations to CI sound quality fell into two groups: One consisted of a restricted frequency bandwidth and spectral smearing while a second was characterized by a wide bandwidth and no spectral smearing. Both sets of modifications were different from those found for patients with shorter electrode arrays who chose upshifts in voice pitch and formant frequencies to match CI sound quality. The data from matching-based metrics of CI sound quality document that speech sound-quality differs for patients fit with different CIs and among patients fit with the same CI.

Impact of age at the second implantation, experience of amplification use, and long-term binaural experience on sound localization of children with bilateral cochlear implants

ObjectivesTo assess the influence of three factors using retrospective chart review: age at which 2nd cochlear implant (CI) is implanted, prior hearing aid (HA) experience in the 2nd CI ear, and long-term experience with bilateral cochlear implants (BICIs) on sound localization in children with sequential BICIs. MethodsMean absolute error (MAE) in localizing speech noise of 60 children with sequential BICIs was compared across four age groups of the 2nd CI (1–5.0; 5.1–10.0; 10.1–14.0; & 14.1–19.0 years) and two extents of prior HA experience (more than and less than one year). MAE was also longitudinally analyzed after 4–6 years of experience with BICI involving 18 participants out of 60. ResultsChildren who received 2nd CI before five years of age demonstrated significantly better localization than those who received it after ten years of age. More than one year of prior HA experience in the 2nd CI ear and extensive experience with sequential BICIs significantly enhanced localization performance. Inter-implant intervals and age at the 2nd CI showed a significant positive correlation with the MAE (poorer localization). ConclusionThe results indicate that age at 2nd CI is important in developing sound localization skills. Based on the results, obtaining 2nd CI within the first five years of life and no later than ten years old is recommended. The results also suggest that longer use of amplification before 2nd CI and prolonged BICI experience significantly fosters localization development.

Duration of cochlear implant use in children with prelingual single-sided deafness is a predictor of word perception in the CI ear

As part of a longitudinal study regarding the benefit of early cochlear implantation for children with single-sided deafness, the current work explored the children's daily device use, potential barriers to full-time device use, and the children's ability to understand speech with the cochlear implant (CI). Data were collected from 20 children with prelingual SSD who received a CI before the age of 2.5 years, from the initial activation of the sound processor until the children were 4.8 to 11.0 years old. Daily device use was extracted from the CI's data logging, while word perception in quiet was assessed using direct audio input to the children's sound processor. The children's caregivers completed a questionnaire about habits, motivations, and barriers to device use.The children with SSD and a CI used their device on average 8.3 h per day, corresponding to 63 % of their time spent awake. All children except one could understand speech through the CI, with an average score of 59 % on a closed-set test and 73 % on an open-set test. More device use was associated with higher speech perception scores. Parents were happy with their decision to pursue a CI for their child. Certain habits, like taking off the sound processor during illness, were associated with lower device use. Providing timely counselling to the children's parents, focused on SSD-specific challenges, may be helpful to improve daily device use in these children.

Objective and Subjective Measures of Spatial Hearing in Unilateral Cochlear Implant Users with Bilateral Profound Hearing Loss

Purpose: The ability to benefit from spatial separation between target and masker signals is important in multi-sound source listening environments. The goal of this study was to measure the spatial release from masking (SRM) in unilateral cochlear implant (CI) users with bilateral profound hearing loss. We also determined the relationships between the SRMs and the self-reported spatial hearing abilities.Methods: Fourteen unilateral CI users with bilateral profound hearing loss participated in this study. The target sentence was always presented to the front of the listener, and the nonfluctuating speech-shaped noise (SSN) or fluctuating speech noise was either co-located with the target (speech at 0°, noise at 0°, S0N0) or spatially separated at ± 90°. The SRM was quantified as the difference between speech recognition thresholds (SRTs) in the co-located and spatially separated conditions. The self-reported spatial hearing abilities were also measured using validated subjective questionnaires.Results: Overall, the SRTs were lower (better) with SSN than with fluctuating speech noise. When the noise was presented to the non-CI ear (speech at 0°, noise at non-CI ear, S0Nnonci), speech-in-noise recognition was the greatest due to head shadow or better-ear listening effect, resulting in the SRMs of approximately 5~6 dB regardless of noise type. When the noise was given to the CI ear (speech at 0°, noise at CI ear, S0Nci), some individuals exhibited positive SRMs (3~8 dB), while others showed negative SRMs, leading to little SRMs overall. When the SSN was given, subjects with less SRMs (less spatial separation benefits on the objective test) reported greater subjective spatial hearing difficulties.Conclusion: The spatial hearing of unilateral CI users varied by the position of the sound source. Listeners' spatial hearing abilities, which are unpredictable from clinical routine tests, need to be assessed by either objective or subjective measures.

Functional Outcomes from Cochlear Implants in Children with Acquired Hearing Loss: Case Studies

Purpose: Early identification of postlingual hearing loss (HL) and knowing its probable cause is of great significance. Causes that result in irreversible profound HL require immediate radiological investigation and intervention to decide the best listening device.Methods: Case reports of three children with acquired HL using cochlear implant (CI) are being presented to understand the functional outcomes in domains of audition and language skills after 12 months of CI use. The age of onset of deafness and implantation were not identical. Etiology of deafness was meningitis in two cases and viral infection in the other. Consent was obtained from the parents for participating in the study. Case history review was conducted to collect demographic and audiological details of the participants. Functional benefits from CI in those children were assessed in the domains of auditory and language skills using standardized assessment tools respectively.Results: Improvements in all domains of auditory and language skills were observed. However, the degree of benefits depended on the duration of deafness, etiology of deafness, age at onset of deafness, age at implantation and effectiveness of intervention.Conclusions: The results of the study can be used during pre-implant CI counselling to facilitate development of real expectations about the functional benefits of CI in children with acquired HL due to various reasons and showed the importance of early cochlear implantation following the diagnosis. These case presentations give an understanding of the various factors that can affect the functional outcome from CI in children with post-lingual HL.

The relationships between language, functional hearing, social, and motor development skills in children with early cochlear implants

PurposeThe purpose of this study was to investigate the relations between functional hearing, language, social, bilateral coordination and manual dexterity skills in children with early cochlear implants (CIs).MethodsThirty children with CIs were included in this study. The manual dexterity and bilateral coordination development of the participants were evaluated with Manual Dexterity and Bilateral Coordination subtests of Bruininks-Oseretsky Motor Proficiency-2 (BOT-2). Their language skills were assessed by the Test of Early language Development-3. To assess the functional hearing of participants the Functioning After Pediatric Cochlear Implantation scale (FAPCI) was administered their caregivers. Also, the Social Skills Evaluation Scale was administered to participants’ teachers to asses their social skills.ResultsThere were significant correlations between participants’ receptive and expressive language skills, Manual Dexterity, and FAPCI scores (p < 0.05). There were also significant relationships between the SSES and FAPCI scores of the participants (p < 0.05). However, the Bilateral Coordination subtest did not show any significant correlation with any of the measurements (p > 0.05).ConclusionThe results suggest that the language, manual dexterity and functional hearing abilities of children with CIs are closely related. Although, there were no significant correlations between all of the measurement, it is important to look beyond hearing and speech evaluations to assess the whole child.

Sensitivity to spectral and temporal cues in music with a cochlear implant in single-sided deaf listeners

Despite the poor sound quality with the cochlear implant (CI), single-sided deaf (SSD) CI users often prefer to listen to music with binaurally combined acoustic and electric hearing. The source of this binaural benefit is unclear. Is the benefit due to gross binaural restoration or synchronous temporal envelope information across ears? Does the detail of the spectral and/or temporal content in the CI ear matter? We investigated sources of binaural benefit for music quality in SSD-CI users by manipulating the input to the CI. Unprocessed music was presented to the acoustic-hearing ear. Experimental stimuli were delivered directly to the CI ear: unprocessed (same as everyday listening), reduced temporal modulations (using a sinewave vocoder to restrict the input to the CI), reduced spectral information (wideband noise modulated by the music temporal envelope), or wideband noise. Preliminary results suggest sensitivity to the spectral and temporal information delivered to the CI ear; however, this sensitivity was highly variable across participants. Binaural benefits were not observed when only temporal cues or white noise were presented to the CI ear. Manipulation of vocoders presented to the CI ear may be a promising approach to evaluate perception of spectral and temporal cues with the CI.

Predicting Early Cochlear Implant Performance: Can Cognitive Testing Help?

There is significant variability in speech recognition outcomes in adults who receive cochlear implants (CIs). Little is known regarding cognitive influences on very early CI performance, during which significant neural plasticity occurs. Prospective study of 15 postlingually deafened adult CI candidates tested preoperatively with a battery of cognitive assessments. The mini-mental state exam (MMSE), forward digit span, Stroop measure of inhibition-concentration, and test of word reading efficiency were utilized to assess cognition. consonant-nucleus-consonant words, AZBio sentences in quiet, and AZBio sentences in noise (+10 dB SNR) were utilized to assess speech recognition at 1- and 3-months of CI use. Performance in all speech measures at 1-month was moderately correlated with preoperative MMSE, but these correlations were not strongly correlated after correcting for multiple comparisons. There were large correlations of forward digit span with 1-month AzBio quiet (P ≤ 0.001, rho = 0.762) and AzBio noise (P ≤ 0.001, rho = 0.860), both of which were strong after correction. At 3 months, forward digit span was strongly predictive of AzBio noise (P ≤ 0.001, rho = 0.786), which was strongly correlated after correction. Changes in speech recognition scores were not correlated with preoperative cognitive test scores. Working memory capacity significantly predicted early CI sentence recognition performance in our small cohort, while other cognitive functions assessed did not. These results differ from prior studies predicting longer-term outcomes. Findings and further studies may lead to better preoperative counseling and help identify patients who require closer evaluation to ensure optimal CI performance.

Improved Postoperative Speech Recognition and Processor Use With Early Cochlear Implant Activation.

To report speech recognition outcomes and processor use based on timing of cochlear implant (CI) activation. Retrospective cohort. Tertiary referral center. A total of 604 adult CI recipients from October 2011 to March 2022, stratified by timing of CI activation (group 1: ≤10 d, n = 47; group 2: >10 d, n = 557). Average daily processor use; Consonant-Nucleus-Consonant (CNC) and Arizona Biomedical (AzBio) in quiet at 1-, 3-, 6-, and 12-month visits; time to peak performance. The groups did not differ in sex ( p = 0.887), age at CI ( p = 0.109), preoperative CNC ( p = 0.070), or preoperative AzBio in quiet ( p = 0.113). Group 1 had higher median daily processor use than group 2 at the 1-month visit (12.3 versus 10.7 h/d, p = 0.017), with no significant differences at 3, 6, and 12 months. The early activation group had superior median CNC performance at 3 months (56% versus 46%, p = 0.007) and 12 months (60% versus 52%, p = 0.044). Similarly, the early activation group had superior median AzBio in quiet performance at 3 months (72% versus 59%, p = 0.008) and 12 months (75% versus 68%, p = 0.049). Both groups were equivalent in time to peak performance for CNC and AzBio. Earlier CI activation was significantly correlated with higher average daily processor use at all follow-up intervals. CI activation within 10 days of surgery is associated with increased early device usage and superior speech recognition at both early and late follow-up visits. Timing of activation and device usage are modifiable factors that can help optimize postoperative outcomes in the CI population.

Pathophysiology of Facial Nerve Stimulation and Its Implications for Electrical Stimulation in Cochlear Implants.

A small number of cochlear implant (CI) users experience facial nerve stimulation (FNS), which can manifest as facial twitching. In some patients, this can be resolved by adjusting the electrical stimulation parameters. However, for others, facial stimulation can significantly impair CI outcomes or even prevent its use. The exact mechanisms underlying FNS are unclear and may vary among patients. Transimpedance measurements were used to assess lateral and longitudinal spread of current within 15 cochlea of nucleus CI recipients with FNS (13 unilateral recipients and 1 bilateral recipient). We compared the transimpedance measurements with programming parameters from clinical visits and pre- and postoperative temporal bone computed tomography (CT) scans to identify factors that may contribute to FNS in each CI ear. In nine ears, transimpedance curves showed inflection, which suggests a localized current sink within the cochlea. This indicates a low-impedance pathway through which current exits the cochlea and stimulates the labyrinthine segment of the facial nerve canal. Electrodes near this current sink were disabled or underfit to minimize facial stimulation. In the other seven ears, current flow peaked toward the basal end of the cochlea, suggesting that current exits through the round window or other structures near the basal end of the cochlea, stimulating the tympanic segment of the facial nerve. Objective transimpedance measurements can be used to elucidate the mechanisms of FNS and to develop strategies for optimizing electrical stimulation parameters and speech coding to minimize or eliminate FNS in a small subset of CI users.

The challenge of a mature final diagnosis of hearing loss severity and early cochlear implantation.

Despite the recent trend of cochlear implantation (CI) at the age of six or even four months is prevalent in many centers around the world, clinicians should be cautious because perinatal risk factors of auditory neuropathy and/or delayed maturation carry the possibility of reversible hearing loss, yielding better auditory performance at the age of one year. The purpose of this study is to raise awareness that early CI may not be universal for all patients. In addition, we specify the factors to be considered in the pre-operative evaluation of CI in infants younger than one year. This study describes four cases provisionally diagnosed with severe to profound sensorineural hearing loss that were presented to the CI clinic to determine candidacy for implantation. Two cases had histories of prematurity, one hadDown syndrome, and one had a family history of hearing loss. None of the study cases were candidates for CI, as they had varying degrees of hearing improvement. Although early CI may yield better auditory performance, the final diagnosis should be made only after repeated subjective and objective measurements as well as family feedback on the child's auditory performance, especially in preterm children. Early auditory brainstem response (ABR) prior to the age of one year in children with cognitive, neurologic, or developmental comorbidities should be interpreted with caution, as ABR "alone" could not accurately represent the child's true hearing ability in this patient population.

Early cochlear implantation for children with single sided deafness

ObjectivesSingle-sided deafness (SSD) can have consequences for a child's language, educational, and social development. A cochlear implant (CI) is the only device which can restore true binaural hearing, yet they are only approved for children with (SSD) over the age of five in the United States. Reports on speech perception outcomes for children implanted at a younger age are limited. The present study aims to examine the effects of age at implantation, duration of deafness, hearing loss etiology, and presence of additional disabilities on device usage and speech perception outcomes. MethodsA retrospective chart review was used to examine demographics and speech perception outcomes for 18 children implanted at age five or younger. ResultsSpeech perception results were highly variable, with some children deriving significant benefit and others demonstrating no sound awareness through the implant alone. Age at implantation and duration of deafness did not have a clear impact on outcomes. Device usage was low in many children, often those with anatomical abnormalities such as a hypoplastic cochlear nerve. There are challenges to assessing speech perception in young children with SSD, leading to a lack of standardized outcome measures. ConclusionsEarly CI for children with SSD may improve speech perception, but benefit is not guaranteed. Candidacy evaluation should consider both medical and audiological factors, in addition to the degree of family support and realistic expectations. Caution is especially warranted in children with significant anatomical anomalies.

Working Memory, Attention Skills and Language Proficiency in Children with Unilateral and Bilateral Cochlear Implants

ABSTRACT Background: Previous studies observed that children with cochlear implants (CIs) have poor language, working memory, and attention skills. The ability to perform cognitive tasks, such as attention and memory, plays a crucial role in the academic achievement and everyday life of children with hearing impairment. Purpose: This study aimed to evaluate and compare the effects of age at the time of implantation and bilateral hearing on cognitive skills, such as language development, working memory, and selective attention, among children with CIs. Research Design: Language skills were assessed using the Test of Language Development-Primary: Fourth Edition (TOLD-P:4), working memory using the Visual-Aural Digit Span Test-Revised Form (VADS-R), and selective attention skills using the Stroop Test TBAG Form. Study sample: A total of 58 participants, comprised of 21 children with early unilateral CIs (before 2 years), 18 children with late unilateral CIs (after 2 years), and 19 children with bilateral CIs, between the ages of 6 and 9 years, were included in the study. Data collection and analysis: According to the age at the time of implantation and whether or not the participant was unilaterally or bilaterally implanted, the mean scores, percentage values, and resultant scores of the participants were calculated using the Mann-Whitney U test. The number of repeated backward digit spans for the VADS-R test, completion times, number of errors and corrections for the Stroop test, raw scores, scaled scores corresponding to raw scores at the relevant age, descriptive terms for the TOLD-P:4 test, and within-group comparisons for all tests were examined. Results: There were significant differences in language, working memory, and attention skills between individuals with early and late unilateral cochlear implantation, whereas there were no significant differences in many subtests between individuals with early unilateral and bilateral cochlear implantation. Conclusion: These findings demonstrate the importance of early cochlear implantation and bilateral hearing on the development of cognitive processes, such as language development, selective attention, and memory skills, which are important factors that may contribute to children's academic performance and overall success.

The road to language through gesture

Abstract This study explores the role of gestures in Flemish Sign Language (VGT) development through a longitudinal observation of three deaf children’s early interactions. These children were followed over a period of one and a half year, at the ages of 6, 9, 12, 18 and 24 months. This research compares the communicative development of a deaf child growing up in a deaf family and two deaf children growing up in hearing families. The latter two children received early cochlear implants when they were respectively 10 and 7 months old. It is the first study describing the types and tokens of children’s gestures used in early dyadic interactions in Flanders (Belgium). The description of our observations shows three distinct developmental patterns in terms of the use of gestures and the production of combinations. The study supports the finding that children’s gestural output is subject to their parental language, and it further indicates an impact of age of cochlear implantation.

Early cochlear implantation supports narrative skills of children with prelingual single-sided deafness

Prelingual single-sided deafness (SSD) not only affects children’s hearing skills, but can also lead to speech-language delays and academic underachievement. Early cochlear implantation leads to improved spatial hearing, but the impact on language development is less studied. In our longitudinal study, we assessed the language skills of young children with SSD and a cochlear implant (CI). In particular, we investigated their narrative skills in comparison to two control groups: children with SSD without a CI, and children with bilateral normal hearing. We found that children with SSD and a CI performed in line with their normal-hearing peers with regard to narrative and verbal short-term memory skills. Children with SSD without a CI had worse narrative (group difference = − 0.67, p = 0.02) and verbal short-term memory (group difference = − 0.68, p = 0.03) scores than the implanted group. Verbal short-term memory scores and grammar scores each correlated positively with narrative scores across all groups. Early grammar scores (at 2–3 years of age) could partially predict later narrative scores (at 4–6 years of age). These results show that young children with prelingual SSD can benefit from early cochlear implantation to achieve age-appropriate language skills. They support the provision of a CI to children with prelingual SSD.

Validating a model of bimodal hearing

Bimodal hearing is defined as using a cochlear implant (CI) on one ear and a hearing aid (HA) on the other ear. This study tested a model of bimodal hearing proposed by Dieudonné and Francart (2020) in 23 bimodal listeners. Firstly, the relative hearing performance of the CI and HA ears was characterized by scores for Consonant-Nucleus-Consonant (CNC) words in quiet. Secondly, Speech Reception Thresholds (SRTs) were measured for CI alone and bimodal listening, with speech (sentences) from the front, and speech-weighted noise either from the front or the HA side. Bimodal benefit (the improvement in SRT when adding a second ear to the subject’s best ear) was 1.2 dB (p &amp;lt; 0.001***) averaged across all subjects. However, for the subset of 18 subjects who obtained better scores with CI alone than HA alone (“CI dominant”), there was no significant bimodal benefit. For the subset of 8 CI-dominant subjects who obtained bimodal benefit when speech and noise were co-located at the front, the benefit was lost when the noise was moved to the HA side, demonstrating that binaural cues were not being used.