Auditory brainstem implant candidacy in the United States in children 0-17 years old

Auditory Brainstem Implant Outcomes in Tumor and Nontumor Patients: A Systematic Review

OBJECTIVE

To elucidate the differences in auditory performance between auditory brainstem implant (ABI) patients with tumor or nontumor etiologies.

DATA SOURCES

PubMed, Embase, and Web of Science Core Collection from 1990 to 2021.

REVIEW METHODS

We included published studies with 5 or more pediatric or adult ABI users. Auditory outcomes and side effects were analyzed with weighted means for closed-set, open-set speech, and categories of auditory performance (CAP) scores. Overall performance was compared using an Adult Pediatric Ranked Order Speech Perception (APROSPER) scale created for this study.

RESULTS

Thirty-six studies were included and underwent full-text review. Data were extracted for 662 tumor and 267 nontumor patients. 83% were postlingually deafened and 17% were prelingually deafened. Studies that included tumor ABI patients had a weighted mean speech recognition of 39.2% (range: 19.6%-83.3%) for closed-set words, 23.4% (range: 17.2%-37.5%) for open-set words, 21.5% (range: 2.7%-48.4%) for open-set sentences, and 3.1 (range: 1.0-3.2) for CAP scores. Studies including nontumor ABI patients had a weighted mean speech recognition of 79.8% (range: 31.7%-84.4%) for closed-set words, 53.0% (range: 14.6%-72.5%) for open-set sentences, and 2.30 (range: 2.0-4.7) for CAP scores. Mean APROSPER results indicate better auditory performance among nontumor versus tumor patients (3.5 vs 3.0, P = .04). Differences in most common side effects were also observed between tumor and nontumor ABI patients.

CONCLUSION

Auditory performance is similar for tumor and nontumor patients for standardized auditory test scores. However, the APROSPER scale demonstrates better ABI performance for nontumor compared to tumor patients.

Speech intelligibility of children with an auditory brainstem implant: a triple-case study

Auditory brainstem implantation (ABI) is a relative recent development in paediatric hearing restoration. Consequently, young-implanted children's productive language has not received much attention. This study investigated speech intelligibility of children with ABI (N = 3) in comparison to children with cochlear implants (CI) and children with typical hearing (TH). Spontaneous speech samples were recorded from children representing the three groups matched on cumulative vocabulary level. Untrained listeners (N = 101) rated the intelligibility of one-word utterances on a continuous scale and transcribed each utterance. The rating task yielded a numerical score between 0 and 100, and similarities and differences between the listeners' transcriptions were captured by a relative entropy score. The speech intelligibility of children with CI and children with TH was similar. Speech intelligibility of children with ABI was well below that of the children with CI and TH. But whereas one child with ABI's intelligibility approached that of the control groups with increasing lexicon size, the intelligibility of the two other children with ABI did not develop in a similar direction. Overall, speech intelligibility was only moderate in the three groups of children, with quite low ratings and considerable differences in the listeners' transcriptions, resulting in high relative entropy scores.

Resection of a meningioma, vestibular schwannoma, and placement of auditory brainstem implant using translabyrinthine approach

The authors present the case of a 34-year-old patient with neurofibromatosis type 2 (NF-2) who underwent a left translabyrinthine approach for resection a meningioma, vestibular schwannoma, and placement of an auditory brainstem implant (ABI). They review the preoperative workup, technical nuances of the surgery, and cadaveric dissections with anatomical diagrams, and provide a review on ABIs. The patient remained neurologically intact and had improvement in lip reading when using the ABI device in the postoperative period.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2163

Internal auditory canal hypoplasia associated with bilateral vestibulocochlear nerve aplasia and deviant facial nerve course: A case report and MRI findings

The evaluation of internal auditory canals and cochlea has gained significant importance due to the increasing number of cochlear implantations worldwide. This region's anatomical study is essential for cochlear implant surgery using magnetic resonance imaging as the method of choice. We report a case of a 6-year-old male patient diagnosed with a rare bilateral malformation of the internal auditory canals associated with an aberrant course of the facial nerve and vestibulocochlear nerve aplasia. This report raises the importance of identifying this rare malformation for appropriate management and reinforces awareness of possible complications.

Clinical and scientific innovations in auditory brainstem implants

The auditory brainstem implant (ABI) was originally developed to provide rehabilitation of retrocochlear deafness caused by neurofibromatosis type 2 (NF2). Recent studies of the ABI have investigated outcomes in non-NF2 cohorts, such as patients with cochlear nerve aplasia or cochlear ossification and more recently, intractable tinnitus. New technologies that improve the ABI-neural tissue interface are being explored as means to improve performance and decrease side effects. Innovative discoveries in optogenetics and bioengineering present opportunities to continually evolve this technology into the future, enhancing spatial selectivity of neuronal activation in the cochlear nucleus and preventing side effects through reduction in activation of non-target neuronal circuitry. These advances will improve surgical planning and ultimately improve patients’ audiological capabilities. ABI research has rapidly increased in the 21st century and applications of this technology are likely to continually evolve. Herein, we aim to characterize ongoing clinical, basic science, and bioengineering advances in ABIs and discuss future directions of this technology.

Autosomal Dominantly Inherited GREB1L Variants in Individuals with Profound Sensorineural Hearing Impairment

Congenital hearing impairment is a sensory disorder that is genetically highly heterogeneous. By performing exome sequencing in two families with congenital nonsyndromic profound sensorineural hearing loss (SNHL), we identified autosomal dominantly inherited missense variants [p.(Asn283Ser); p.(Thr116Ile)] in GREB1L, a neural crest regulatory molecule. The p.(Thr116Ile) variant was also associated with bilateral cochlear aplasia and cochlear nerve aplasia upon temporal bone imaging, an ultra-rare phenotype previously seen in patients with de novo GREB1L variants. An important role of GREB1L in normal ear development has also been demonstrated by greb1l^-/- zebrafish, which show an abnormal sensory epithelia innervation. Last, we performed a review of all disease-associated variation described in GREB1L, as it has also been implicated in renal, bladder and genital malformations. We show that the spectrum of features associated with GREB1L is broad, variable and with a high level of reduced penetrance, which is typically characteristic of neurocristopathies. So far, seven GREB1L variants (14%) have been associated with ear-related abnormalities. In conclusion, these results show that autosomal dominantly inherited variants in GREB1L cause profound SNHL. Furthermore, we provide an overview of the phenotypic spectrum associated with GREB1L variants and strengthen the evidence of the involvement of GREB1L in human hearing.

Pediatric Auditory Brainstem Implant Users Compared With Cochlear Implant Users With Additional Disabilities

OBJECTIVES

To evaluate long-term language development in children with prelingual deafness who received auditory brainstem implants (ABIs) compared with children who received cochlear implants (CIs) at the same hospital. Additional non-auditory disabilities were taken into account.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Ten children with bilateral malformations of the cochlea and/or cochlear nerve who received ABIs, including seven with additional disabilities, and 147 children with CIs as a reference group, including 22 children with additional disabilities.

INTERVENTION

ABIs were implanted at 1.3 to 6.2 years of age. Follow-up ranged from 1.1 to 7.7 years.

MAIN OUTCOME MEASURES

Receptive and expressive language abilities were assessed using the Infant Toddler Meaningful Auditory Integration Scale (IT-MAIS), the Categories of Auditory Performance (CAP), the Meaningful Use of Speech Scale (MUSS), and the Speech Intelligibility Rate (SIR).

RESULTS

Of the 10 children with ABIs, seven had long-term follow-up data. Within 1 year, six of the seven children with ABIs could identify sounds, respond to speech, and use their voice to attract attention. Language skills developed at a slower rate than in children with CIs and reached the same competence level when additional disabilities were absent. These language skills matched, on average, those of children with CIs with additional disabilities.

CONCLUSION

For deaf children with bilateral inner ear malformations, ABIs provide satisfactory auditory input. Children with ABIs are able to develop receptive and expressive language skills comparable to those of children with CIs with additional disabilities. Using this knowledge, preoperative parent counselling can be refined.

Three-Dimensional Surface Reconstruction of the Human Cochlear Nucleus: Implications for Auditory Brain Stem Implant Design

Objective  The auditory brain stem implant (ABI) is a neuroprosthesis placed on the surface of the cochlear nucleus (CN) to provide hearing sensations in children and adults who are not candidates for cochlear implantation. Contemporary ABI arrays are stiff and do not conform to the curved brain stem surface. Recent advancements in microfabrication techniques have enabled the development of flexible surface arrays, but these have only been applied in animal models. Herein, we measure the surface curvature of the human CN and adjoining regions to assist in the design and placement of next-generation conformable clinical ABI arrays. Three-dimensional (3D) reconstructions from ultrahigh T1-weighted brain magnetic resonance imaging (MRI) sequences and histologic reconstructions based on postmortem adult human brain stem specimens were used. Design  This is a retrospective review of radiologic data and postmortem histologic axial sections. Setting  This is set at the tertiary referral center. Participants  Data were acquired from healthy adults. Main Outcome Measures  The main outcome measures are principal curvature values (Kmin and Kmax) and global radius of curvature. Results  The CN was successfully extracted and rendered as a 3D surface in all cases. Significant curvatures of the CN in both histologic and radiographic reconstructions were found with global radius of curvature ranging from 2.08 to 8.5 mm. In addition, local curvature analysis revealed that the surface is highly complex. Conclusion  Detailed rendering of the human CN is feasible using histology and 3D MRI reconstruction and highlights complex surface topography that is not recapitulated by contemporary stiff ABI arrays.

Clinical Profile and Results Obtained in Patients Treated by Auditory Brainstem Implants

INTRODUCTION

Cochlear implants have been able to treat some types of hearing loss, but those related to cochlear nerve impairment made it necessary to find new ways to manage these deficits; leading to auditory brainstem implants (ABI).

AIM

Our objective is to present the clinical profile of patients treated through an ABI and the results obtained from 1997 to 2017.

MATERIAL AND METHODS

On the one hand, patients with statoacoustic nerve tumours (VIIIcranial nerve) were selected, and on the other hand, patients withoutVIII tumours with congenital malformations of the inner ear. Before and after the placement of the ABI, hearing was assessed through tonal audiometry, from which the PTA (Pure Tone Average) and the CAP (Categories of Auditory Performance) scale were obtained.

RESULTS

A total of 20 patients undergoing ABI surgery were included. Eight were of tumour cause (40%) and 12 non-tumour (60%). In 15 subjects (75%) a suboccipital approach was performed and in 5 (25%) translabyrinthine. The mean of active electrodes before the implantation of Cochlear® (Nucleus ABI24) was 13/21 (61.90%) versus 8.5/12 (70.83%) of the Med-el® (ABI Med-el). An improvement in the mean PTA of 118.49dB was found against 46.55dB at 2years. On the CAP scale, values of1 were obtained in the preimplantation and of 2.57 (1-5) in the 2-year revision.

CONCLUSION

The ABI is a safe option, and with good hearing results when the indication is made correctly.

Special Populations in Implantable Auditory Devices: Pediatric

"Hearing loss in the pediatric population can have significant social and developmental implications. Early auditory rehabilitation by at least 6 months of age is imperative. Although traditional hearing aids are often a first-line treatment option, there is a wide array of implantable auditory devices available. This article describes the indications for such devices as they pertain to the pediatric population, including osseointegrated bone-conduction devices, middle ear implants, cochlear implants, and auditory brainstem implants."

Auditory Brainstem Implants: Recent Progress and Future Perspectives

The auditory brainstem implant (ABI) was first developed nearly 40 years ago and provides auditory rehabilitation to patients who are deaf and ineligible for cochlear implant surgery due to abnormalities of the cochlea and cochlear nerve. The aims of the following review are to describe the history of the ABI and innovations leading up to the modern ABI system, as well as highlight areas of future development in implant design.

Auditory brainstem implant in postmeningitis totally ossified cochleae

INTRODUCTION

An auditory brainstem implant (ABI) is an option for auditory rehabilitation in patients with totally ossified cochleae who cannot receive a conventional cochlear implant.

OBJECTIVE

To evaluate the outcomes in audiometry and speech perception tests after the implantation of an ABI via the extended retrolabyrinthine approach in patients with postmeningitis hearing loss.

MATERIALS AND METHODS

Ten patients, including children and adults, with postmeningitis hearing loss and bilateral totally ossified cochleae received an ABI in a tertiary center from 2009 to 2015. The extended retrolabyrinthine approach was performed in all the patients by the same surgeons. A statistical analysis compared pure tonal averages and speech perception tests before and at least 12 months after the ABI activation.

RESULTS

Eight patients (80%) showed improvements in tonal audiometry and the word and vowel perception tests after an average follow-up of 3.3 years. Two patients recognized up to 40% of the closed-set sentences without lip-reading. Two patients had no auditory response.

CONCLUSIONS

The ABI improved hearing performance in audiometry and speech perception tests in cases of postmeningitis hearing loss. The extended retrolabyrinthine approach is a safe surgical option for patients with postmeningitis hearing loss and bilateral totally ossified cochleae.

De novo variants in GREB1L are associated with non-syndromic inner ear malformations and deafness

Congenital inner ear malformations affecting both the osseous and membranous labyrinth can have a devastating impact on hearing and language development. With the exception of an enlarged vestibular aqueduct, non-syndromic inner ear malformations are rare, and their underlying molecular biology has thus far remained understudied. To identify molecular factors that might be important in the developing inner ear, we adopted a family-based trio exome sequencing approach in young unrelated subjects with severe inner ear malformations. We identified two previously unreported de novo loss-of-function variants in GREB1L [c.4368G>T;p.(Glu1410fs) and c.982C>T;p.(Arg328*)] in two affected subjects with absent cochleae and eighth cranial nerve malformations. The cochlear aplasia in these affected subjects suggests that a developmental arrest or problem at a very early stage of inner ear development exists, e.g., during the otic pit formation. Craniofacial Greb1l RNA expression peaks in mice during this time frame (E8.5). It also peaks in the developing inner ear during E13-E16, after which it decreases in adulthood. The crucial function of Greb1l in craniofacial development is also evidenced in knockout mice, which develop severe craniofacial abnormalities. In addition, we show that Greb1l-/- zebrafish exhibit a loss of abnormal sensory epithelia innervation. An important role for Greb1l in sensory epithelia innervation development is supported by the eighth cranial nerve deficiencies seen in both affected subjects. In conclusion, we demonstrate that GREB1L is a key player in early inner ear and eighth cranial nerve development. Abnormalities in cochleovestibular anatomy can provide challenges for cochlear implantation. Combining a molecular diagnosis with imaging techniques might aid the development of individually tailored therapeutic interventions in the future.

Early Communication Development of Children with Auditory Brainstem Implants

The auditory brainstem implant (ABI) is an auditory sensory device that is surgically placed on the cochlear nucleus of the brainstem for individuals who are deaf but unable to benefit from a cochlear implant (CI) due to anatomical abnormalities of the cochlea and/or eighth nerve, specific disease processes, or temporal bone fractures. In the United States, the Food and Drug Administration has authorized a Phase I clinical trial to determine safety and feasibility of the ABI in up to 10 eligible young children who are deaf and either derived no benefit from the CI or were anatomically unable to receive a CI. In this paper, we describe the study protocol and the children who have enrolled in the study thus far. In addition, we report the scores on speech perception, speech production, and language (spoken and signed) for five children with 1-3 years of assessment post-ABI activation. To date, the results indicate that spoken communication skills are slow to develop and that visual communication remains essential for post-ABI intervention.

Pediatric Auditory Brainstem Implant Surgery

Auditory brainstem implants (ABIs) provide auditory perception in patients with profound hearing loss who are not candidates for the cochlear implant (CI) because of anatomic constraints or failed CI surgery. Herein, the authors discuss (1) preoperative evaluation of pediatric ABI candidates, (2) surgical approaches, and (3) contemporary ABI devices and their use in the pediatric population. The authors also review the surgical and audiologic outcomes following pediatric ABI surgery. The authors' institutional experience and the nearly 200 cases performed in Europe and the United States indicate that ABI surgery in children can be safe and effective.

Experiences from Auditory Brainstem Implantation (ABIs) in four paediatric patients

INTRODUCTION

Indications for auditory brainstem implants (ABIs) have been widened from patients with neurofibromatosis type 2 (NF2) to paediatric patients with congenital cochlear malformations, cochlear nerve hypoplasia/aplasia, or cochlear ossification after meningitis. We present four ABI surgeries performed in children at Uppsala University Hospital in Sweden since 2009.

METHODS

Three children were implanted with implants from Cochlear Ltd. (Lane Cove, Australia) and one child with an implant from MedEl GMBH (Innsbruck, Austria). A boy with Goldenhar syndrome was implanted with a Cochlear Nucleus ABI24M at age 2 years (patient 1). Another boy with CHARGE syndrome was implanted with a Cochlear Nucleus ABI541 at age 2.5 years (patient 2). Another boy with post-ossification meningitis was implanted with a Cochlear Nucleus ABI24M at age 4 years (patient 3). A girl with cochlear aplasia was implanted with a MedEl Synchrony ABI at age 3 years (patient 4). In patients 1, 2, and 3, the trans-labyrinthine approach was used, and in patient 4 the retro-sigmoid approach was used.

RESULTS

Three of the four children benefited from their ABIs and use it full time. Two of the full time users had categories of auditory performance (CAP) score of 4 at their last follow up visit (6 and 2.5 years postoperative) which means they can discriminate consistently any combination of two of Ling's sounds. One child has not been fully evaluated yet, but is a full time user and had CAP 2 (responds to speech sounds) after 3 months of ABI use. No severe side or unpleasant stimulation effects have been observed so far. There was one case of immediate electrode migration and one case of implant device failure after 6.5 years.

CONCLUSION

ABI should be considered as an option in the rehabilitation of children with similar diagnoses.