Hearing restoration with auditory brainstem implant in three children with cochlear nerve aplasia

Auditory Brainstem Implants-Hearing Restoration in Congenitally Deaf Children

BACKGROUND

Children who are born deaf can learn to hear and to speak with the aid of a cochlear implant (CI). If the implantation of a CI is not possible for anatomical reasons, an auditory brainstem implant (ABI) is the only surgical option for auditory rehabilitation. It is estimated that about 5 to 45 children could potentially benefit from this treatment in Germany each year. In this article, we present and discuss the current state of the scientific evidence.

METHODS

The PubMed and Embase databases were searched for relevant publications from 2010 onward. 15 articles reporting at least 10 cases with at least one year of auditory follow-up were included in the analysis. The results, including CAP ("categories of auditory performance") scores on a scale of 0 to 7, are presented and compared with the authors' own findings in a series of 38 patients.

RESULTS

All of the publications show that children who do not suffer from impairments of other kinds hear significantly better with an ABI than those with additional handicaps. Early implantation is advantageous, under the age of three years if possible. The results vary widely across publications and from patient to patient. The mean CAP score in all publications is 3.57 (standard deviation [SD], 1.04). 38.24% of the patients (SD 18.68) achieved the ability to understand spoken language (CAP ≥= 5), more specifically, the ability to communicate in everyday life without lip reading, in person and some even succeed in conversing over the telephone.

CONCLUSION

ABI is a safe and effective treatment for sensorineural deafness in congenitally deaf children who cannot be treated with a cochlear implant. In particular, children without any other impairments have a good chance of developing the ability to understand spoken language, especially if the implantation is performed early.

Word characteristics and speech production accuracy in children with auditory brainstem implants: a longitudinal triple case report

Auditory brainstem implants (ABI) in children in the first years of life is a recent innovation. Analyses of their speech and language development on the basis of spontaneous language samples are still largely lacking. The aim was to investigate the phonological complexity of the words children with ABI use in their spontaneous speech, and to compare their accuracy with that of children with cochlear implants (CI) and children with normal hearing (NH). Longitudinal recordings of spontaneous speech were collected of three children with ABI. Children with ABI target mainly words of low phonological complexity in their spontaneous speech, just as children with NH and children with CI do. The complexity of the words they attempt increases over time, but this development is less outspoken in comparison to children with CI and NH at the same hearing ages. The accuracy of the ABI children's word productions is situated in the lower ranges of the 95% confidence intervals of the NH and the CI groups, and - depending on the specific measure - even fall below the 95% border. The ABI intervention appears to be beneficial in the three cases studied, although their development is slow compared to children with CI and NH.

Evaluation of phoneme recognition skills in pediatric auditory brainstem implant users

OBJECTIVES

This study aims to evaluate the relationship between phoneme recognition skills and language development skills in pediatric auditory brainstem implant (ABI) users. It further intends to identify the delays and problems that may occur in the phoneme recognition skills of children with ABI and shed light on rehabilitation programs.

METHODS

Our study included 20 children using ABI and another 20 using cochlear implants (CI). They were aged between 6 and 8 years 11 months. The participants exhibited homogenous demographic and audiological characteristics. The Turkish version of the Test of Language Development-Primary: Fourth Edition (TOLDP:4) was used to evaluate the language development skills, and the Turkish version of the Phoneme Recognition Test (PRT) was applied to assess the phoneme recognition skills.

RESULTS

There was a statistically significant difference (p < 0.05) in the PRT values as well as in the language development skills between the children with ABI and those with CI. It was observed that the values of the children with CI were significantly higher than those of children with ABI.

CONCLUSION

Although children with ABI were not able to match the skills of their peers with CI, their language development and communication skills improved. It is believed that this study will contribute to the literature by demonstrating that the use of ABI improves phoneme recognition skills in children who are not eligible for CI or who do not adequately benefit from CI.

ABI-auditory brainstem implant

The Auditory Brainstem Implant (ABI) is based on the classic cochlear implant (CI) but uses a different stimulation electrode. At MED-EL, the early development activities on ABI started in the year 1994, with the suggestion coming from J. Helms and J. Müller from Würzburg, Germany in collaboration with the Univ. of Innsbruck Austria. The first ABI surgery in a neuro-fibromatosis (NF2) patient with the MED-EL device took place in the year 1997. Later, the indication of ABI was expanded to non-NF2 patients with severe inner-ear malformation, for whom a regular CI will not be beneficial. Key translational research activities at MED-EL in collaboration with numerous clinics investigating the factors that affect the hearing performance amongst ABI patients, importance of early ABI implantation in children, tools in pre-operative assessment of ABI candidates and new concepts that were pursued with the MED-EL ABI device. The CE-mark for the MED-EL ABI to be used in adults and children down to the age of 12 months without NF-2 was granted in 2017 mainly based on two long-term clinical studies in the pediatric population. This article covers the milestones of translational research from the first concept to the widespread clinical use of ABI in association with MED-EL.

Effects of Age at Auditory Brainstem Implantation: Impact on Auditory Perception, Language Development, Speech Intelligibility

OBJECTIVE

To study the effect of age at auditory brainstem implant (ABI) surgery on auditory perception, language, and speech intelligibility.

STUDY DESIGN

Retrospective single cohort design.

SETTING

Tertiary referral center.

PATIENTS

In this study, 30 pediatric ABI users with no significant developmental issues were included. Participants were divided into two groups, according to age at surgery (Early Group: < 3 yr old [n = 15], Late Group: ≥ 3 yr old [n = 15]). Groups were matched by duration of ABI use and participants were evaluated after 5 years (±1 yr) experience with their device. The mean age at ABI surgery was 22.27 (ranged ± 6.5) months in the early group, 45.53 (ranged ± 7.9) months in the late group.

INTERVENTION(S)

Retrosigmoid craniotomy and ABI placement.

MAIN OUTCOME MEASURE(S)

Auditory perception skills were evaluated using the Meaningful Auditory Integration Scale and Categories of Auditory Performance from the Children's Auditory Perception Test Battery. We used a closed-set pattern perception subtest, a closed-set word identification subtest, and an open-set sentence recognition subtest. Language performance was assessed with the Test of Early Language Development and Speech Intelligibility Rating, which was administered in a quiet room.

RESULTS

In this study, the results demonstrated that the Early Group's auditory perception performance was better than the Late Group after 5 years of ABI use, when children had no additional needs (U = 12, p < 0.001). Speech intelligibility was the most challenging skill to develop, in both groups. Due to multiple regression analysis, we found that auditory perception categories can be estimated with speech intelligibility scores, pattern perception scores, receptive language scores, and age at ABI surgery variables in ABI users with no additional handicaps.

CONCLUSIONS

ABI is a viable option to provide auditory sensations for children with cochlear anomalies. ABI surgery under age 3 is associated with improved auditory perception and language development compared with older users.

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.

Auditory brainstem implantation in children with hearing loss: Effect on speech production

Auditory brainstem implantation (ABI) is a recent technique in children's hearing restoration. Up till now the focus in the literature has mainly been the perceptual outcomes after implantation, whereas the effect of ABI on spoken language is still an almost unexplored area of research. This study presents a one-year follow-up of the volubility of two children with ABI. The volubility of signed and oral productions is investigated and oral productions are examined in more detail. Results show clear developmental trends in both children, indicating a beneficial effect of ABI on spoken language development.

Pediatric Auditory Brainstem Implantation: Surgical, Electrophysiologic, and Behavioral Outcomes

OBJECTIVES

The objectives of this study were to demonstrate the safety of auditory brainstem implant (ABI) surgery and document the subsequent development of auditory and spoken language skills in children without neurofibromatosis type II (NFII).

DESIGN

A prospective, single-subject observational study of ABI in children without NFII was undertaken at the University of North Carolina at Chapel Hill. Five children were enrolled under an investigational device exemption sponsored by the investigators. Over 3 years, patient demographics, medical/surgical findings, complications, device mapping, electrophysiologic measures, audiologic outcomes, and speech and language measures were collected.

RESULTS

Five children without NFII have received ABIs to date without permanent medical sequelae, although 2 children required treatment after surgery for temporary complications. All children wear their device daily, and the benefits of sound awareness have developed slowly. Intra-and postoperative electrophysiologic measures augmented surgical placement and device programming. The slow development of audition skills precipitated limited changes in speech production but had little impact on growth in spoken language.

CONCLUSIONS

ABI surgery is safe in young children without NFII. Benefits from device use develop slowly and include sound awareness and the use of pattern and timing aspects of sound. These skills may augment progress in speech production but progress in language development is dependent upon visual communication. Further monitoring of this cohort is needed to better delineate the benefits of this intervention in this patient population.

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.

Expressive Vocabulary Growth After Pediatric Auditory Brainstem Implantation in Two Cases' Spontaneous Productions: A Comparison With Children With Cochlear Implants and Typical Hearing

Auditory brainstem implants (ABI) are recently being used to restore hearing of children with a congenital hearing loss, due to for instance the absence of auditory nerves. Thus far, the literature has focused on perceptual outcomes. The present study is among the first ones to investigate the spoken language development after implantation. The lexical development of children with ABI is examined longitudinally in comparison to children with typical hearing and children with cochlear implants. Results show that children with ABI still have smaller spoken vocabularies as compared to (hearing) age-matched children with cochlear implants and children with typical hearing. Implications will be discussed.

Pediatric Auditory Brainstem Implantation: Impact on Audiological Rehabilitation and Tonal Language Development

OBJECTIVE

This is a retrospective review of the impact of an Auditory Brainstem Implant (ABI) on the audiological rehabilitation and tonal language development of pediatric patients with prelingual profound deafness in Hong Kong.

RESULTS

From January 2009 to February 2015, 11 pediatric patients with profound prelingual deafness received an ABI in Hong Kong (age range 1.67-3.75 years). Etiologies included Cochlear Nerve Deficiency in 7, Severe Cochlear Malformations in 2, and Retrocochlear Deafness in 2. All of them were rehabilitated in Cantonese, a dialect of Chinese. Standard pediatric cochlear implant outcome measurements were used in this study that comprised of the 7-Sound Detection, Syllable Identification, Vowel Identification, Consonant Identification, Tone Imitation, Tone Production and Speech Perception Category. Audiological rehabilitation and speech development outcomes were reviewed. Age-matched outcomes of pediatric cochlear implant users were used for comparisons.

CONCLUSION

Encouraging results of speech development were found, especially with continued use of the ABI. There was considerable variation in outcomes. Children with coexisting developmental and nonauditory cognitive disabilities did not perform as well. Auditory brainstem implantation is a safe and beneficial treatment for profound prelingual deafness in Cantonese-speaking pediatric patients.

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.

Electrically Evoked Auditory Event-Related Responses in Patients with Auditory Brainstem Implants: Morphological Characteristics, Test-Retest Reliability, Effects of Stimulation Level, and Association with Auditory Detection

OBJECTIVE

This study aimed to (1) characterize morphological characteristics of the electrically evoked cortical auditory event-related potentials (eERPs) and explore the potential association between onset eERP morphology and auditory versus nonauditory stimulation; (2) assess test-retest reliability of onset eERPs; (3) investigate effects of stimulation level on onset eERPs; and (4) explore the feasibility of using the onset eERP to estimate the lowest stimulation level that can be detected for individual stimulating electrodes in patients with auditory brainstem implants (ABIs).

DESIGN

Study participants included 5 children (S1 to S5) and 2 adults (S6 to S7) with unilateral Cochlear Nucleus 24M ABIs. Pediatric ABI recipients ranged in age from 2.6 to 10.2 years (mean: 5.2 years) at the time of testing. S6 and S7 were 21.2 and 24.6 years of age at the time of testing, respectively. S6 and S7 were diagnosed with neurofibromatosis II (NF2) and implanted with an ABI after a surgical removal of the tumors. All pediatric subjects received ABIs after being diagnosed with cochlear nerve deficiency. The lowest stimulation level that could be detected (behavioral T level) and the estimated maximum comfortable level (C level) was measured for individual electrodes using clinical procedures. For electrophysiological measures, the stimulus was a 100-msec biphasic pulse train that was delivered to individual electrodes in a monopolar-coupled stimulation mode at stimulation levels ranging from subthreshold to C levels. Electrophysiological recordings of the onset eERP were obtained in all subjects. For studies evaluating the test-retest reliability of the onset eERP, responses were measured using the same set of parameters in two test sessions. The time interval between test sessions ranged from 2 to 6 months. The lowest stimulation level that could evoke the onset eERP was defined as the objective T level.

RESULTS

Onset eERPs were recorded in all subjects tested in this study. Inter- and intrasubject variations in morphological characteristics of onset eERPs were observed. Onset eERPs with complex waveforms were recorded for electrodes that evoked nonauditory sensations, based on feedback from subjects, as well as for electrodes without any indications of nonauditory stimulations. Onset eERPs in patients with ABIs demonstrated good test-retest reliability. Increasing stimulation levels resulted in increased eERP amplitudes but showed inconsistent effects on response latencies in patients with ABIs. Objective and behavioral T levels were correlated.

CONCLUSIONS

eERPs could be recorded in both non-NF2 and NF2 patients with ABIs. eERPs in both ABI patient groups show inter- and intrasubject variations in morphological characteristics. However, onset eERPs measured within the same subject in this study tended to be stable across study sessions. The onset eERP can potentially be used to estimate behavioral T levels in patients with ABIs. Further studies with more adult ABI recipients are warranted to investigate whether the onset eERP can be used to identify electrodes with nonauditory stimulations.

The value of intraoperative EABRs in auditory brainstem implantation

OBJECTIVE

To compare the intraoperative electrically evoked auditory brainstem response (EABR) morphologies between neurofibromatosis II (NF2) adult auditory brainstem implant (ABI) recipients who had auditory percepts post-operatively and those who did not and between NF2 adult ABI recipients and non-NF2 pediatric ABI recipients.

METHODS

This was a retrospective case series at a single tertiary academic referral center examining all ABI recipients from 1994 to 2016, which included 34 NF2 adults and 11 non-NF2 children. The morphologies of intraoperative EABRs were evaluated for the number of waveforms showing a response, the number of positive peaks in those responses, and the latencies of each of these peaks.

RESULTS

27/34 adult NF2 patients and 9/10 children had EABR waveforms. 20/27 (74.0%) of the adult patients and all of the children had ABI devices that stimulated post-operatively. When comparing the waveforms between adults who stimulated and those who did not stimulate, the proportion of total number of intraoperative EABR peaks to total possible peaks was significantly higher for the adults who stimulated than for those who did not (p < 0.05). Children had a significantly higher proportion of total number of peaks to total possible peaks when compared to adults who stimulated (p < 0.02). Additionally, there were more likely to be EABR responses at the initial stimulation than intraoperatively in the pediatric ABI population (p = 0.065).

CONCLUSIONS

The value of intraoperative EABR tracing may lie in its ability to predict post-operative auditory percepts based on the placement of the array providing the highest number of total peaks.

Cochlear Nerve Aplasia and Hypoplasia: Predictors of Cochlear Implant Success

Objective

To identify factors predicting performance outcomes following cochlear implantation in patients with cochlear nerve aplasia or hypoplasia.

Data Sources

Individual patient data extracted from published case series and reports.

Review Methods

The MEDLINE database, Cochrane Library, Embase, Web of Science, and Google Scholar were queried for “cochlear implant” in conjunction with “aplasia” or “hypoplasia” between 1985 and 2015. Eighteen studies were included describing 97 subjects with individual postimplant auditory data. Postimplant performance was categorized as follows: level 1, nonstimulation/minimal detection; level 2, improved detection; level 3, closed-set speech perception; or level 4, open-set speech perception. The subjects achieving speech perception (levels 3 and 4) were descriptively compared with those who did not.

Results

Subjects with a hypoplastic cochlear nerve on magnetic resonance imaging had higher reported rates of achieving speech perception than those with an aplastic nerve. Subjects with syndromic medical comorbidities had higher reported rates of nonstimulation than nonsyndromic subjects. The data showed that some children with an aplastic cochlear nerve or those with partial electrode insertion could obtain levels of speech discrimination. Reporting of patient characteristics and auditory outcomes was extremely variable across studies.

Conclusion

As previously shown, cochlear implant in patients with cochlear nerve aplasia or hypoplasia can provide meaningful hearing for select patients. The current study suggests that presence of a cochlear nerve on magnetic resonance imaging and lack of comorbid medical syndrome are associated with better auditory outcomes in such patients. Future efforts to report individual data in a consistent manner may allow better determination of predictive factors.

Auditory Rehabilitation in Rhesus Macaque Monkeys (Macaca mulatta) with Auditory Brainstem Implants

Background:

The auditory brainstem implants (ABIs) have been used to treat deafness for patients with neurofibromatosis Type 2 and nontumor patients. The lack of an appropriate animal model has limited the study of improving hearing rehabilitation by the device. This study aimed to establish an animal model of ABI in adult rhesus macaque monkey (Macaca mulatta).

Methods:

Six adult rhesus macaque monkeys (M. mulatta) were included. Under general anesthesia, a multichannel ABI was implanted into the lateral recess of the fourth ventricle through the modified suboccipital-retrosigmoid (RS) approach. The electrical auditory brainstem response (EABR) waves were tested to ensure the optimal implant site. After the operation, the EABR and computed tomography (CT) were used to test and verify the effectiveness via electrophysiology and anatomy, respectively. The subjects underwent behavioral observation for 6 months, and the postoperative EABR was tested every two weeks from the 1^st month after implant surgery.

Result:

The implant surgery lasted an average of 5.2 h, and no monkey died or sacrificed. The averaged latencies of peaks I, II and IV were 1.27, 2.34 and 3.98 ms, respectively in the ABR. One-peak EABR wave was elicited in the operation, and one- or two-peak waves were elicited during the postoperative period. The EABR wave latencies appeared to be constant under different stimulus intensities; however, the amplitudes increased as the stimulus increased within a certain scope.

Conclusions:

It is feasible and safe to implant ABIs in rhesus macaque monkeys (M. mulatta) through a modified suboccipital RS approach, and EABR and CT are valid tools for animal model establishment. In addition, this model should be an appropriate animal model for the electrophysiological and behavioral study of rhesus macaque monkey with ABI.

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.

The electrically evoked cortical auditory event-related potential in children with auditory brainstem implants

OBJECTIVE

This study explored the feasibility of measuring electrically evoked cortical auditory event-related potentials (eERPs) in children with auditory brainstem implants (ABIs).

DESIGN

Five children with unilateral ABIs ranging in age from 2.8 to 10.2 years (mean: 5.2 years) participated in this study. The stimulus was a 100-msec biphasic pulse train that was delivered to individual electrodes in a monopolar stimulation mode. Electrophysiological recordings of the onset eERP were conducted in all subjects.

RESULTS

The onset eERP was recorded in four subjects who demonstrated auditory perception. These eERP responses showed variations in waveform morphology across subjects and stimulating electrode locations. No eERPs were observed in one subject who received no auditory sensation from ABI stimulation.

CONCLUSIONS

eERPs can be recorded in children with ABIs who develop auditory perception. The morphology of the eERP can vary across subjects and also across stimulating electrode locations within subjects.

Nervus Intermedius Guides Auditory Brainstem Implant Surgery in Children with Cochlear Nerve Deficiency

OBJECTIVE

To investigate the anatomic features of the nervus intermedius and cranial nerve VII in children with cochlear nerve deficiency and to verify whether the nervus intermedius can provide an additional landmark to help guide placement of the auditory brainstem implant electrode.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

High-definition video was captured during retrosigmoid surgery in 64 children (mean age, 3.91 ± 2.83 years) undergoing auditory brainstem implant placement. These videos were examined with particular reference to the number and variety of nervus intermedius bundles and any associated facial nerve anomalies.

RESULTS

Absence of cranial nerves VI, VII, and VIII was observed in 3, 6, and all 64 children, respectively. Fifteen children had several abnormalities of the facial nerve in the cerebellopontine angle. Anatomic identification of the facial nerve and the bundles composing the nervus intermedius was possible in 46 children. In 12 children, identification was possible with the assistance of intraoperative monitoring. The number of bundles composing the nervus intermedius varied from 1 to 6. The nervus intermedius and cranial nerve IX were useful landmarks for identifying the foramen of Luschka of the lateral recess.

CONCLUSION

The nervus intermedius provides an additional landmark during auditory brainstem microsurgery since it was identified in all subjects. The nervus intermedius anatomy and its topographic relationship with the neurovascular structures around the foramen of Luschka have been described for the first time in children with cochlear nerve deficiency.

Self-reported benefit, sound perception, and quality-of-life in patients with auditory brainstem implants (ABIs)

CONCLUSION

The majority of the patients used their auditory brainstem implants (ABIs) all the time, reporting that he/she would make the decision to receive an implant again if the decision were reconsidered. The findings support that the ABI is a valuable treatment in patients with type 2 neurofibromatosis (NF2) and in children with congenital inner ear and nerve anomalies or cochlear ossification.

OBJECTIVE

To evaluate the patients who underwent ABI implantation in Uppsala during 1993-2013. This study analyzed patients' implant use, perception of environmental sounds, perceived benefit from the implant, and quality-of-life (QoL).

METHOD

The NF2-patients (n = 20) comprised the majority of the patients, and there were a few non-NF2 pediatric patients (n = 4). The exclusion criteria included deceased patients (n = 4) and patients with no hearing sensations from the implant, or those with an inactivated ABI (n = 2). The data were collected from a questionnaire survey.

RESULTS

Eleven adult patients and two pediatric patients answered the questionnaires. Eight of the adult patients used their implants 'always'. The two children always used their implants. Hearing problems had the largest negative effect on the QoL. The non-users and the users scored equally on the NFTI-QoL.

Systematic Review of Nontumor Pediatric Auditory Brainstem Implant Outcomes

OBJECTIVE

The auditory brainstem implant (ABI) was initially developed for patients with deafness as a result of neurofibromatosis type 2. ABI indications have recently extended to children with congenital deafness who are not cochlear implant candidates. Few multi-institutional outcome data exist. Herein, we aim to provide a systematic review of outcomes following implantation of the ABI in pediatric patients with nontumor diagnosis, with a focus on audiometric outcomes.

DATA SOURCES

PubMed, Embase, and Cochrane.

REVIEW METHODS

A systematic review of literature was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations. Variables assessed included age at implantation, diagnosis, medical history, cochlear implant history, radiographic findings, ABI device implanted, surgical approach, complications, side effects, and auditory outcomes.

RESULTS

The initial search identified 304 articles; 21 met inclusion criteria for a total of 162 children. The majority of these patients had cochlear nerve aplasia (63.6%, 103 of 162). Cerebrospinal fluid leak occurred in up to 8.5% of cases. Audiometric outcomes improved over time. After 5 years, almost 50% of patients reached Categories of Auditory Performance scores >4; however, patients with nonauditory disabilities did not demonstrate a similar increase in scores.

CONCLUSION

ABI surgery is a reasonable option for the habilitation of deaf children who are not cochlear implant candidates. Although improvement in Categories of Auditory Performance scores was seen across studies, pediatric ABI users with nonauditory disabilities have inferior audiometric outcomes.

Unilateral auditory neuropathy spectrum disorder: retrocochlear lesion in disguise?

Objective:

To investigate whether the aetiology for hearing impairment in neonates with unilateral auditory neuropathy spectrum disorder could be explained by structural abnormalities such as cochlear nerve aplasia, a cerebellopontine angle tumour or another identifiable lesion.

Methods:

In this prospective case series, 17 neonates were diagnosed with unilateral auditory neuropathy spectrum disorder on electrophysiological testing. Diagnostic audiology testing, including auditory brainstem response testing, was supplemented with computed tomography and/or magnetic resonance imaging.

Results:

Ten of the neonates (59 per cent) showed evidence for cochlear nerve aplasia. Of the remaining seven, four were shown to have another abnormality of the temporal bone on imaging. Only three neonates (18 per cent) were not diagnosed with cochlear nerve aplasia or another lesion. Three computed tomography scans were reported as normal, but subsequent magnetic resonance imaging revealed cochlear nerve aplasia.

Conclusion:

Auditory neuropathy spectrum disorder as a unilateral condition mandates further investigation for a definitive diagnosis. This series demonstrates that most neonates with unilateral auditory neuropathy spectrum disorder had pathology as visualised on computed tomography and/or magnetic resonance imaging scans. Magnetic resonance imaging is an appropriate first-line imaging modality.

Aplasia of the cochlea: radiologic assessment and options for hearing rehabilitation

OBJECTIVE

Hearing rehabilitation of patients with severe inner ear malformations remains controversial. Our objective was to describe the radiologic findings of aplasia of the cochlea (AC) and evaluate the existing therapeutic options in such patients.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Pediatric and adult patients with AC evaluated at our institution from 1995 to 2010.

INTERVENTIONS

The precise radiologic findings were identified using high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) scans of the inner ear. In cases of auditory implantation on the AC side, the achieved outcome was recorded using categories of auditory performance (CAP). Related surgical aspects were analyzed.

RESULTS

Twenty-three patients (28 ears) with AC were found. In 5 patients AC was bilateral. The remaining unilateral cases had contralateral normal ears (2 patients), cochlea hypoplasia (5 patients), common cavity (6 patients), incomplete partition Type I (4 patients), and atresia of the internal auditory canal (1 patient). Four patients (3 bilateral, 1 unilateral ACs) were treated with cochlear implants in ears with AC, and 1 patient underwent auditory brainstem implantation. All implanted patients achieved speech perception with limited vocabulary (CAP scores between 4 and 5).

CONCLUSION

AC is defined as the total absence of the cochlea, with a present, although malformed, vestibule. Although a distinct auditory nerve was not seen in these cases of AC, results following cochlear implantation suggest functional cochlear nerve fibers in the remaining dysplastic inner ear structures. In selected cases, cochlear implantation may be a reasonable option for the habilitation of deafness associated with AC.

An unusual case of bilateral agenesis of the cochlear nerves

Imaging of the cochlea and internal auditory canals are increasingly important nowadays because of the growing number of cochlear implants being performed throughout the world. We report a case of a 4-year-old boy who was born deaf and was being evaluated in our service for possible cochlear implantation. Audiometry disclosed profound bilateral deafness. The magnetic resonance imaging revealed only two nerves in each inner auditory canal: one in the anterior superior quadrant, identified as the facial nerve, and one on the posterior quadrants, representing both the superior and inferior vestibular nerves. The semicircular canals were not seen and the vestibule had dysplastic morphology. The diagnosis was bilateral agenesis of the cochlear nerves and semicircular canals.

Cochlear implantation in children with cochlear nerve deficiency: a report of nine cases

OBJECTIVE

Cochlear implantation for children with cochlear nerve deficiency remains controversial, as the presence of the cochlear nerve has been central to the success of cochlear implantation. This study sought to investigate whether there is any benefit from cochlear implantation for children with cochlear nerve deficiency.

METHODS

Nine children with cochlear nerve deficiency and bilateral prelingual profound sensorineural hearing loss were included in this study. Inner ear and internal auditory canal structures were evaluated using magnetic resonance imaging and temporal bone computed tomography scans. Meaningful auditory integration scales, categories of auditory performance scores, speech intelligibility ratings and pure tone average threshold with cochlear implantation were measured for evaluation of hearing and speech performance.

RESULTS

Only four (44.4%) children had a significant improvement in pure tone average threshold with the cochlear implant device (77.5 dBHL, 45 dBHL, 51.3 dBHL and 68.8 dBHL). No child achieved sufficient speech intelligibility or perception ability during a follow-up of at least one year after surgery.

CONCLUSIONS

The decision to perform cochlear implantation in children with cochlear nerve deficiency must be undertaken with caution as it has limited effectiveness and uncertain cost-benefit.

Retrolabyrinthine approach for surgical placement of auditory brainstem implants in children

CONCLUSION

The extended retrolabyrinthine approach (RLA) is a safe and reliable approach for auditory brainstem placement in children. The surgical landmarks to reach cochlear nucleus are adequately exposed by this approach.

OBJECTIVE

To describe a new approach option for auditory brainstem implants (ABIs) in children, highlighting the anatomical landmarks to appropriately expose the foramen of Luschka.

METHODS

Three prelingually deafened children consecutively operated for ABIs via the RLA.

RESULTS

ABI placement via the RLA was successfully performed in all children without any further complications except multidirectional nystagmus in one child. The RLA we employed differed from that used for vestibular schwannoma only in the removal of the posterior semicircular canal. The lateral and superior semicircular canals and the vestibule remained intact, and there was no need to expose the dura of the internal auditory meatus. The jugular bulb was completely exposed to allow adequate visualization of the ninth cranial nerve and cerebellar flocculus.

Advances in auditory prostheses

PURPOSE OF REVIEW

Auditory prostheses use electric currents on multiple electrodes to stimulate auditory neurons and recreate auditory sensations in deaf people. Cochlear implants have restored hearing in more than 200  000 deaf adults and children to a level that allows most to understand speech. Here we review the reasons underlying these results and describe new directions in restoring hearing to additional patient populations and the design of new devices.

RECENT FINDINGS

From their early development about 50 years ago, cochlear implants have been well received and beneficial to people who had lost their hearing. Although those first implants did not allow high levels of speech understanding, they provided auditory information that worked synergistically with lip reading to improve communication. Present day cochlear implants provide excellent speech understanding in children and in postlingually deafened adults. Research is focused on improved signal processing and new electrode designs. Electric stimulation of the auditory brainstem can also produce excellent hearing in some children and adults.

SUMMARY

Auditory prostheses, both at the level of the sensory nerve and at the brainstem, can restore patterns of neural activation that are sufficient for high levels of speech understanding. These prostheses are not only clinically successful but also important tools for understanding sensory processing in the brain.

Congenital bilateral facial nerve hypoplasia with sensorineural hearing loss: a case report

A 3-year-old child presented with congenital bilateral facial nerve palsy with bilateral profound sensorineural hearing loss. High Resolution Computed Tomogram (HRCT) of the temporal bones found bilateral atresia of cochlear nerve canals, incomplete partition of the cochleae and narrow facial nerve canals. Magnetic resonance imaging (MRI) revealed bilateral hypoplasia of facial nerves and aplasia of both vestibulocochlear nerves. There have been no other reported cases with this presentation. The possible aetiology and treatment options for the patient are discussed. We highlighted the review of aplasia/hypoplasia of the facial nerve and hypoplasia of cochlear nerve canal.

Symptom timeline preceding cochlear implant failure: an institutional experience

OBJECTIVE

Review cochlear explants and determine the incidence of device and medical failures and develop a pattern of symptoms indicating probable implant failure.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Subjects were selected if they underwent cochlear explantation. Data were reviewed to determine initial symptom and symptom timeline preceding implant failure.

RESULTS

A total of 847 implants were performed from 1988 to 2008, with 128 devices explanted. Of total implants, 72% were Advanced Bionic devices, and 28% were Cochlear Nucleus devices. Overall failure rate was 128 of 847 (15%), with 51 (6%) medical failures and 77 (9%) device failures. Patients with Advanced Bionic devices underwent 102 explants (16.7% failure rate), with 35% medical failures and 65% device failures. Patients with Nucleus devices underwent 26 explants (11% failure rate), with 58% medical failures and 42% device failures. Medical failures included infected devices and wound dehiscence, with the pattern averaging 4.5 months to explantation. Hard device failures included sudden malfunction and slow decline in function, with pattern of failure over 4.2 months. Soft failures included tinnitus and discomfort, with failure over 8 months.

CONCLUSIONS

There were common patterns when evaluating both medical and device failures. By recognizing patterns of symptoms that may indicate probable implant failure, otolaryngologists can better counsel patients on what to expect with their implants when they present with certain symptoms.

The High Rate CIS Auditory Brainstem Implant for Restoration of Hearing in NF-2 Patients

AIM

Hearing preservation is one of the major goals of acoustic neuroma surgery. In NF-2 patients, bilateral hearing loss is frequently caused by the disease or results from its treatment. Several implant devices for electrical stimulation of the cochlear nucleus have been developed to restore serviceable hearing in these patients. We report our experience and results using a high rate continuous interleaved sampling (CIS) auditory brainstem implant (ABI).

METHODS

Between June 1997 and May 2004, 24 NF-2 patients were managed by our group. In 20 patients an ABI was implanted successfully. The cochlear nucleus was located using anatomical landmarks and E-ABR recordings after resection of the neuroma via a retrosigmoid approach in the semi-sitting position. The 12-channel stimulating electrode array was inserted and fixed in the lateral recess. There were no surgical complications related to implantation apart from pseudomeningo that were managed by lumbar drainage.

RESULTS

In one patient the electrode array became dislocated and this necessitated revision surgery which was successful. One patient failed to gain benefit from the implant. Overall, 70% of electrodes were found to be serviceable for auditory stimulation, 5.3% of electrodes were primarily nonauditory, and in 7.8% side effects during stimulation were observed. Lip reading was improved by more than 100% as a result of the additional auditory input. For many patients, comprehension of open speech was restored to a useful level. Almost all patients were able to perceive environmental sounds and tinnitus was masked.

CONCLUSIONS

Restoration of hearing using ABIs in NF-2 patients is a safe and promising procedure for those who would otherwise be totally deaf. The high rate CIS speech processing strategy has proven to be very useful and effective in direct cochlear nucleus stimulation.

Auditory Brainstem Implants

Auditory brainstem implants (ABIs) are currently indicated for patients with neurofibromatosis type 2 (NF-2) tumors involving both vestibulocochlear nerves. The ABI helps bypass the damaged cochlear nerves and stimulates the cochlear nucleus in the brainstem directly thereby restoring auditory sensation. The implant is usually placed in the lateral recess of the fourth ventricle after tumor resection. The indications for ABI have recently expanded onto even nontumoral cases, such as congenital bilateral cochlear nerve aplasia. In such cases, the ABI helps bypass the nonfunctioning hypoplastic or absent cochlear nerves and stimulates the cochlear nucleus directly thereby restoring auditory sensation. This article reviews the nuances of this sophisticated implant, shares our experience with auditory brainstem implantation and its current status in world literature.

[Present state of cochlear implant treatment in adults and children]

The technique of cochlear implantation was the first method which allowed replacement of a sense organ by a (partially) implantable electronic prosthesis. By this method the cells of the spiral ganglion of the cochlea are directly stimulated by the electrodes introduced into the cochlea, bypassing the functions of the outer and middle ear as well as the cochlea. Treatment with a cochlear implant (CI) has been established over the last 20-30 years as a reliable method for restoring hearing in adults and children with severe hearing disorders and is now a routine method in many centers. For optimal results in understanding speech and for children in the speech development phase, rehabilitation must be an integral part of the total treatment and follow soon after implantation. To achieve this early diagnosis of hearing difficulties or deafness is necessary, which is simplified by a consistent hearing screening of newborns, now a statutory procedure in Germany.

Nonverbal cognitive abilities and auditory performance in children fitted with auditory brainstem implants: preliminary report

OBJECTIVES/HYPOTHESIS

Auditory brainstem implants (ABIs) can provide excellent open set speech recognition in adults without auditory tumors. These favorable results prompted us to extend ABI indications to children with profound hearing loss (HL) who are not candidates for a cochlear implant (CI). This article reports on the auditory performance and cognitive development measured in children with ABIs.

STUDY DESIGN

This study quantifies the development of auditory perceptual and nonverbal cognitive abilities of children with profound HL undergoing ABI. From 2000 to 2006, 17 children aged 14 months to 16 years received an ABI for different tumor and nontumor diseases in our department in Verona, and nine children were operated in other countries. Six of the children had been previously fitted elsewhere with a CI with no auditory results. Fourteen children had multiple associated psychomotor handicaps.

METHODS

The retrosigmoid approach was used in all children. Intraoperative and postoperative electrically evoked auditory brainstem responses were performed in all children. Perceptual auditory abilities were evaluated with the Evaluation of Auditory Responses to Speech battery and the Category of Auditory Performance test. Cognitive evaluation was performed on 10 children using the Leiter International Performance Scale-Revised test.

RESULTS

All children consistently use their devices for 8 h/d at average and have environmental sound awareness and utterance of words and simple sentences. Their category of auditory performance test scores increased significantly with ABI use. Scores on two of the four subtests considered for cognitive evaluation in this study increased significantly (P < .05) during the first year of ABI use. Postimplant cognitive outcomes were positively related to the auditory results.

CONCLUSIONS

The present investigation clearly indicates that children who are not candidates for CI fitted with ABI obtain significant development of their hearing ability and a significant improvement in some cognitive parameters. The outcomes of the present study suggest that children with cochlear or cochlear nerve abnormalities with associated cognitive deficits should not be excluded from ABI implantation.

Implante auditivo de tronco encefálico: revisão de literatura

OBJETIVO: pesquisar aspectos relevantes sobre implante auditivo de tronco encefálico como conceito, finalidade, métodos de implantação, indicações do procedimento e benefícios. MÉTODOS: realizou-se compilação dos trabalhos disponíveis nas bases de dados LILACS, MEDLINE e SCIELO utilizando os descritores: implante auditivo de tronco encefálico, reabilitação de deficientes auditivos, perda auditiva neurossensorial, procedimentos cirúrgicos otológicos. RESULTADOS: o implante auditivo de tronco encefálico é semelhante ao implante coclear, exceto pela configuração do eletrodo que é projetado para ser colocado no complexo do núcleo coclear, no tronco encefálico. Originalmente foi desenvolvido para restaurar a audição em pacientes com ausência ou lesão no nervo coclear. Hoje é indicado para pacientes que por motivos anatômicos ou funcionais não podem receber estímulos elétricos pela orelha interna, como em casos de malformação/ausência de nervo coclear, ossificação coclear e neuropatia auditiva. Os efeitos relatados são: restabelecimento da audição em pacientes com perda auditiva total, níveis de detecção e discriminação dos sons similares às obtidas com implante coclear e acesso a sons ambientais e da fala. CONCLUSÃO: o implante auditivo de tronco encefálico proporciona o restabelecimento da sensação auditiva em sujeitos não beneficiados pelo uso de próteses auditivas e implante coclear. A quase totalidade dos pacientes implantados obteve algum benefício na comunicação.