Cochlear implantation in children with postlingual hearing loss

Overcoming developing-world challenges in cochlear implantation: A Nigerian perspective

The emergence of cochlear implantation (CI) in the mid-20th century was a transformation to the field of restorative otology. The advance in this field has not been felt in lower-income countries where a huge burden of profound hearing loss lies. The authors sought to review the literature on the practice of cochlea implantation in Nigeria. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews, we conducted a scoping review of the literature on CI in Nigeria. All observational studies with information on cochlear implants and/or implantation in Nigeria were included with no limitations on outcomes. The authors extracted the following data; age, sample size, sex, aetiology, outcome, type of devices, complications, challenges and the location of the surgery. The results were pooled and reported as frequencies and percentages. Three studies were utilised in this review. The study included 25 patients. The age of the identified patients ranged from 1.2 months to 63 years. There were slightly more males than females (52% males). The most common aetiology of deafness in the participants was following a febrile illness (40%), followed by deafness post-meningitis (24%). The challenges identified included high cost, lack of full rehabilitative facilities and staff, scepticism, and lack of funding. CI remains the most effective for those that are profoundly deaf. Although successful CI programmes exist in Nigeria, the number of implant programmes and the affordability are not yet commensurate to the needs of the entire Nigerian population.

The relationship between preoperative factors and the pattern of longitudinal improvement in speech perception following cochlear implantation

BACKGROUND

Many studies have discussed the factors influencing hearing outcomes after cochlear implantation, but few have addressed improvements in speech perception for these patients over time.

OBJECTIVE

To investigate the relationship between preoperative factors and the pattern of longitudinal improvement in speech perception following cochlear implantation (CI).

MATERIALS AND METHODS

This study enrolled 83 patients (96 ears) who underwent CI at Shinshu University Hospital. The patients were assessed up to 12 months after CI by a monosyllable test, and showed either delayed improvement (DI), early improvement (EI), or stable improvement (SI) when compared with their preoperative score. Eight preoperative variables were also examined for their effects on speech perception over time.

RESULTS

The DI, EI, SI groups comprised 35.4%, 43.8%, and 20.8% of all patients, respectively. Patients in the DI group were older at surgery than those in the EI and SI groups, and their onset age were also older than that in the SI group. No other preoperative variables showed significant differences across the three groups.

CONCLUSIONS AND SIGNIFICANCE

Our findings revealed that age at implantation and age at onset of hearing loss significantly affected the improvement pattern of speech perception. Age may be useful in predicting recovery of speech perception after CI.

Resting-state EEG reveals global network deficiency in prelingually deaf children with late cochlear implantation

There are individual differences in rehabilitation after cochlear implantation that can be explained by brain plasticity. However, from the perspective of brain networks, the effect of implantation age on brain plasticity is unclear. The present study investigated electroencephalography functional networks in the resting state, including eyes-closed and eyes-open conditions, in 31 children with early cochlear implantation, 24 children with late cochlear implantation, and 29 children with normal hearing. Resting-state functional connectivity was measured with phase lag index, and we investigated the connectivity between the sensory regions for each frequency band. Network topology was examined using minimum spanning tree to obtain the network backbone characteristics. The results showed stronger connectivity between auditory and visual regions but reduced global network efficiency in children with late cochlear implantation in the theta and alpha bands. Significant correlations were observed between functional backbone characteristics and speech perception scores in children with cochlear implantation. Collectively, these results reveal an important effect of implantation age on the extent of brain plasticity from a network perspective and indicate that characteristics of the brain network can reflect the extent of rehabilitation of children with cochlear implantation.

Location Effects on Spoken Language and Literacy for Children who are DHH

The purpose of this study was to consider how living in an area that qualifies for a rural health grant interacts with a child's hearing status to affect early language and literacy development. Four-year-old children with hearing aids (n = 45), cochlear implants (n = 47), and with typical hearing (n = 66) completed measures of spoken language knowledge and of emergent literacy skills as part of a larger longitudinal investigation. A significant interaction effect between location (rural or urban/suburban) and amplification group was detected for letter knowledge: children with hearing aids exhibit a performance that is particularly affected by rural location. Overall, children with cochlear implants performed lower across all measures than children with typical hearing, and children with hearing aids performed lower than children with typical hearing on measures of phonological awareness, vocabulary, omnibus language knowledge and articulation.

Meta-Analytic Findings on Reading in Children With Cochlear Implants

This meta-analysis study aims to quantify the group differences in reading skills between children with cochlear implants and their hearing peers and between children with cochlear implants and children with hearing aids (aged between 3 and 18 years old). Of the 5,642 articles screened, 47 articles met predetermined inclusion criteria (published between 2002 and 2019). The robust variance estimation based meta-analysis models were used to synthesize all the effect sizes. Children with cochlear implants scored significantly lower than their hearing peers in phonological awareness (g = -1.62, p < 0.001), vocabulary (g = -1.50, p < 0.001), decoding (g = -1.24, p < 0.001), and reading comprehension (g = -1.39, p < 0.001), but not for fluency (g = -0.67, p = 0.054). Compared to children with hearing aids, children with cochlear implants scored significantly lower in phonological awareness (g = -0.30, p = 0.028). The percentage of unilateral cochlear implant negatively impacts the group difference between children with cochlear implants and their hearing peers. Findings from this study confirm a positive shift in reading outcomes for profoundly deaf children due to cochlear implantation. Some children with cochlear implants may need additional supports in educational settings.

Residual Cochlear Function in Adults and Children Receiving Cochlear Implants: Correlations With Speech Perception Outcomes

OBJECTIVES

Variability in speech perception outcomes with cochlear implants remains largely unexplained. Recently, electrocochleography, or measurements of cochlear potentials in response to sound, has been used to assess residual cochlear function at the time of implantation. Our objective was to characterize the potentials recorded preimplantation in subjects of all ages, and evaluate the relationship between the responses, including a subjective estimate of neural activity, and speech perception outcomes.

DESIGN

Electrocochleography was recorded in a prospective cohort of 284 candidates for cochlear implant at University of North Carolina (10 months to 88 years of ages). Measurement of residual cochlear function called the "total response" (TR), which is the sum of magnitudes of spectral components in response to tones of different stimulus frequencies, was obtained for each subject. The TR was then related to results on age-appropriate monosyllabic word score tests presented in quiet. In addition to the TR, the electrocochleography results were also assessed for neural activity in the forms of the compound action potential and auditory nerve neurophonic.

RESULTS

The TR magnitude ranged from a barely detectable response of about 0.02 µV to more than 100 µV. In adults (18 to 79 years old), the TR accounted for 46% of variability in speech perception outcome by linear regression (r = 0.46; p < 0.001). In children between 6 and 17 years old, the variability accounted for was 36% (p < 0.001). In younger children, the TR accounted for less of the variability, 15% (p = 0.012). Subjects over 80 years old tended to perform worse for a given TR than younger adults at the 6-month testing interval. The subjectively assessed neural activity did not increase the information compared with the TR alone, which is primarily composed of the cochlear microphonic produced by hair cells.

CONCLUSIONS

The status of the auditory periphery, particularly of hair cells rather than neural activity, accounts for a large fraction of variability in speech perception outcomes in adults and older children. In younger children, the relationship is weaker, and the elderly differ from other adults. This simple measurement can be applied with high throughput so that peripheral status can be assessed to help manage patient expectations, create individually-tailored treatment plans, and identify subjects performing below expectations based on residual cochlear function.

Cochlear Implantation: An Overview

A cochlear implant (CI) is a surgically implanted device for the treatment of severe to profound sensorineural hearing loss in children and adults. It works by transducing acoustic energy into an electrical signal, which is used to stimulate surviving spiral ganglion cells of the auditory nerve. The past 2 decades have witnessed an exponential rise in the number of CI surgeries performed. Continual developments in programming strategies, device design, and minimally traumatic surgical technique have demonstrated the safety and efficacy of CI surgery. As a result, candidacy guidelines have expanded to include both pre and postlingually deaf children as young as 1 year of age, and those with greater degrees of residual hearing. A growing proportion of patients are undergoing CI for off-label or nontraditional indications including single-sided deafness, retrocochlear hearing loss, asymmetrical sensorineural hearing loss (SNHL) in adults and children with at least 1 ear that is better than performance cut-off for age, and children less than 12 months of age. Herein, we review CI design, clinical evaluation, indications, operative technique, and outcomes. We also discuss the expanding indications for CI surgery as it relates to lateral skull base pathology, comparing CI to auditory brainstem implants, and address the concerns with obtaining magnetic resonance imaging (MRI) in CI recipients.

Clinical role of electrocochleography in children with auditory neuropathy spectrum disorder

OBJECTIVES

To assess electrocochleography (ECochG) to tones as an instrument to account for CI speech perception outcomes in children with auditory neuropathy spectrum disorder (ANSD).

MATERIALS & METHODS

Children (<18 years) receiving CIs for ANSD (n = 30) and non-ANSD (n = 74) etiologies of hearing loss were evaluated with ECochG using tone bursts (0.25-4 kHz). The total response (TR) is the sum of spectral peaks of responses across frequencies. The compound action potential (CAP) and the auditory nerve neurophonic (ANN) in ECochG waveforms were used to estimate nerve activity and calculate nerve score. Performance on open-set monosyllabic word tests was the outcome measure. Standard statistical methods were applied.

RESULTS

On average, TR was larger in ANSD than in non-ANSD subjects. Most ANSD (73.3%) and non-ANSD (87.8%) subjects achieved open-set speech perception; TR accounted for 33% and 20% of variability in the outcomes, respectively. In the ANSD group, the PTA accounted for 69.3% of the variability, but there was no relationship with outcomes in the non-ANSD group. In both populations, nerve score was sensitive in identifying subjects at risk for not acquiring open-set speech perception, while the CAP and the ANN were more specific.

CONCLUSION

In both subject groups, the TRs correlated with outcomes but these measures were notably larger in the ANSD group. There was also strong correlation between PTA and speech perception outcome in ANSD group. In both subject populations, weaker evidence of neural activity was related to failure to achieve open-set speech perception.

Predictors of pediatric cochlear implantation outcomes in South Africa

OBJECTIVE

To identify and describe predictors of pediatric cochlear implantation outcomes in a South African population.

METHODS

A retrospective study of 301 pediatric cochlear implant (CI) recipients from five CI programs was conducted and cross-sectional outcome data were added at the time of data collection. Twenty potential prognostic factors were identified from the retrospective dataset, including demographical, CI, risk and family factors. Multiple regression analyses were performed to identify predictor variables that influence outcomes in terms of auditory performance (CAP scores), speech production (SIR scores), communication mode and educational placement.

RESULTS

Although implanted children within this sample did not have equal opportunity to access a second implant, bilateral implantation was strongly predictive of better auditory performance and speech production scores, an oral mode of communication and mainstream education. NICU admittance/prematurity were associated with poorer auditory performance and speech production scores, together with a higher probability for non-oral communication and non-mainstream education. The presence of one or more additional developmental condition was predictive of poorer outcomes in terms of speech production and educational placement, while a delay between diagnosis and implantation of more than one year was also related to non-mainstream education. Ethnicities other than Caucasian were predictive of poorer auditory performance scores and a lower probability for mainstream education.

CONCLUSION

An extensive range of prognostic indicators were identified for pediatric CI outcomes in South Africa. These predictive factors of better and poorer outcomes should guide pediatric CI services to promote optimal outcomes and assist professionals in providing evidence-based informational counseling.

A global patient outcomes registry: Cochlear paediatric implanted recipient observational study (Cochlear(™) P-IROS)

BACKGROUND

Currently, there is a paucity of data concerning the long-term outcomes, educational placement and quality of life of children implanted with hearing devices from large and representative samples of the population. To address this concern, a large, prospective, multicentre, multinational patient-outcomes registry for paediatric recipients of implantable hearing devices was developed. The benefits of this registry, its approach and methodology are described.

METHODS/DESIGN

The Cochlear(™) Paediatric Implanted Recipient Observational Study (Cochlear P-IROS) is a prospective international patient-outcomes registry for children who are implanted in routine clinical practice with one or more hearing devices. The study aims to collect data on patient comorbidities, device use, auditory performance, quality of life and health-related utilities, across different types of implantable hearing devices from a range of manufacturers. Patients will be evaluated with a set of standardised and non-standardised questionnaires prior to initial device activation (baseline) and at six-monthly follow-up intervals up to 24 months and annually thereafter. The Cochlear P-IROS utilises a secure web interface to administer electronic case report forms to clinicians and families of implanted children. The web interface is currently available in five languages: English, Japanese, Korean, Mandarin and Russian. The interface also provides printable versions of the case report forms translated into 22 local languages for collection of data prior to entry online; additional languages may be added, as required. Participation in the Cochlear P-IROS registry is investigator-driven and voluntary. To date, the Cochlear P-IROS has recruited implant clinics across Australia, China, India, Indonesia, Turkey and Vietnam. The registry also aims to recruit multiple clinics in Cuba, Israel, Japan, Malaysia, Singapore, South Africa, South Korea and Russia.

DISCUSSION

The use of a registry such as the Cochlear P-IROS will generate valuable data to support research interests of academics and clinicians around the globe. The data generated will be relevant for a wide range of stakeholders including regulators, payers, providers, policy makers, patients and their families, each with a different perspective for the acceptance and adoption of implantable hearing devices for the treatment of hearing loss.

Functional changes in people with different hearing status and experiences of using Chinese sign language: an fMRI study

The purpose of this study was to assess functional changes in the cerebral cortex in people with different sign language experience and hearing status whilst observing and imitating Chinese Sign Language (CSL) using functional magnetic resonance imaging (fMRI). 50 participants took part in the study, and were divided into four groups according to their hearing status and experience of using sign language: prelingual deafness signer group (PDS), normal hearing non-signer group (HnS), native signer group with normal hearing (HNS), and acquired signer group with normal hearing (HLS). fMRI images were scanned from all subjects when they performed block-designed tasks that involved observing and imitating sign language stimuli. Nine activation areas were found in response to undertaking either observation or imitation CSL tasks and three activated areas were found only when undertaking the imitation task. Of those, the PDS group had significantly greater activation areas in terms of the cluster size of the activated voxels in the bilateral superior parietal lobule, cuneate lobe and lingual gyrus in response to undertaking either the observation or the imitation CSL task than the HnS, HNS and HLS groups. The PDS group also showed significantly greater activation in the bilateral inferior frontal gyrus which was also found in the HNS or the HLS groups but not in the HnS group. This indicates that deaf signers have better sign language proficiency, because they engage more actively with the phonetic and semantic elements. In addition, the activations of the bilateral superior temporal gyrus and inferior parietal lobule were only found in the PDS group and HNS group, and not in the other two groups, which indicates that the area for sign language processing appears to be sensitive to the age of language acquisition.

LEARNING OUTCOMES

After reading this article, readers will be able to: discuss the relationship between sign language and its neural mechanisms.

Paediatric cochlear implantation in north-western Nigeria case report and review of our challenges

OBJECTIVE

To report the commencement of cochlear implantation (CI) in children in Northern Nigeria and review the challenges encountered with a view to establishing CI programme.

CASES

Two children with post-meningitic sensorineural hearing loss had standard pre-implantation assessment and cochlear implantation surgery in Nigeria in conjunction with surgeons from another developing country. Post-implantation meningitis was encountered and managed in one of the patients. Post-CI rehabilitation started in a foreign country and continued in our centre after training of our speech therapist. Both patients had improvement in their hearing.

CONCLUSION

These showcase successful CI in patients from Sub-Saharan Africa, the challenges included need for development of surgical and post-CI rehabilitation personnel and affordability of the cost of the implant. The support of all the stakeholders needed for commencement of a CI programme was noted.

Cochlear implantation for single-sided deafness: the outcomes. An evidence-based approach

The aim of the present paper is to critically review the current evidence on the efficacy of cochlear implantation as a treatment modality for single-sided deafness (SSD), and/or unilateral tinnitus. Systematic literature review in Medline and other database sources was conducted along with critical analysis of pooled data. The study selection includes prospective and retrospective comparative studies, case series and case reports. The total number of analyzed studies was 17. A total of 108 patients with SSD have been implanted; 66 patients due to problems associated with SSD, and 42 primarily because of debilitating tinnitus. Cochlear implantation in SSD leads to improved sound localization performance and speech perception in noise from the ipsilateral side with an angle of coverage up to (but not including) 90(°) to the front, when noise is present in the contralateral quartile (Strength of recommendation B). Speech and spatial hearing also subjectively improve following the insertion of a cochlear implant (Strength of recommendation B); this was not the case regarding the quality of hearing. Tinnitus improvement was also reported following implant placement (Strength of recommendation B); however, patients need to be advised that the suppression is mainly successful when the implant is activated. The overall quality of the available evidence supports a wider use of cochlear implantation in SSD following appropriate selection and counseling (overall strength of recommendation B). It remains to be seen if the long-term follow-up of large number of patients in well conducted high quality studies will confirm the above mentioned results.