Favorable Outcome of Cochlear Implant in VIIIth Nerve Deficiency

A Systematic Review and Meta-analysis Examining Outcomes of Cochlear Implantation in Children With Bilateral Cochlear Nerve Deficiency

OBJECTIVE

To assess hearing and speech outcomes in pediatric patients with bilateral cochlear nerve deficiency (CND) who underwent cochlear implantation (CI) and to identify factors associated with improved outcomes.

DATABASES REVIEWED

PubMed, Embase, Web of Science, and Cochran databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

METHODS

Studies that reported hearing and speech outcomes of pediatric patients with bilateral CND who underwent CI were included. Demographics, comorbidities, inner ear abnormalities, CND classification (aplasia or hypoplasia), details of diagnostic workup, and outcomes data were extracted. Outcomes were assessed using the four-level auditory performance level (APL) scale. Meta-analysis, using Cochran-Armitage tests, was performed on patients with individual data to assess factors associated with performance.

RESULTS

A total of 314 papers were screened, and 40 papers with 378 total patients met inclusion criteria. A total of 339 patients had patient-level data and were included in the meta-analysis. Of the 339 patients, 19% (n = 63) of patients had no measurable stimulation, 28% (n = 95) had improved detection, 22% (n = 76) achieved closed-set speech perception, and 31% (n = 105) achieved open-set speech perception. Patients with cochlear nerve aplasia (p = 0.016) and syndromes (p < 0.001) had significantly worse APL scores relative to patients with cochlear nerve hypoplasia and patients without syndromes, respectively.

CONCLUSIONS

While most patients with bilateral CND benefit from CI and almost one-third of patients achieved open-set speech perception, outcomes were heterogenous and one-fifth of patients did not experience measurable benefit from CI.

Outcome of cochlear implantation in a case of cochlear aplasia with cochlear nerve deficiency

Cochlear nerve deficiency in cochlear aplasia is a contraindication for cochlear implantation (CI) anticipating poor auditory response. Few authors have reported auditory outcomes even without nerves following CI. This study outlines the audiological outcomes of a patient in early childhood with cochlear aplasia and cochlear nerve deficiency who underwent CI. Auditory and speech-language development were assessed using the Categories of Auditory Performance (CAP) scale, Speech Intelligibility Rating (SIR) scale and Ling-6 sound test; at the time of switch-on, after 6 and 12 months of auditory verbal therapy. Significant differences across CAP, SIR and Ling-6 sound detection scores were noted, with the highest mean scores at the 12th-month postimplantation, indicating substantial improvement in auditory and speech-language skills. In cochlear aplasia cases, residual cochlear elements and nerve fibres cannot be ruled out. Our report emphasises the need for research, as this has the potential to impact the existing guidelines for CI candidacy.

[Prospects for cochlear implantation in patients with auditory nerve dysplasia]

Auditory nerve dysplasia (AND) can encompass various conditions of the auditory nerve (AN), ranging from true aplasia to hypoplasia. The purpose of this review is to discuss the prospect of cochlear implantation (CI) and subsequent auditory speech rehabilitation for AN abnormality. Studies of different authors when working with this category of children, possible results and methods of diagnostics of the AN condition are presented.

Cochlear Implantation in Meniere's Disease: A Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

Meniere's disease (MD) is a debilitating condition characterized by hearing loss, vertigo, and tinnitus. The objective of this study was to systematically investigate outcomes in MD after cochlear implantation (CoI), with and without labyrinthectomy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of articles in Medline and Embase was performed to identify all studies of patients with MD who underwent CoI. This analysis evaluates outcomes of speech recognition, pure tone audiometry, vertigo, tinnitus, and quality of life.

RESULTS

Of 321 studies identified, 37 were included, involving 216 patients. Mean age at implantation was 61.4 years (range 27-85 years) with average length of follow-up at 1.7 years (range 0-9 years). Forty-four (20.4%) patients underwent labyrinthectomy. Meta-analysis demonstrated significant improvements in audiometric outcomes following CoI. There was a statistically significant improvement in Hearing in Noise Test performance, with a mean difference improvement of 44.7 (95% confidence interval [CI] [8.8, 80.6]) at 6 months and 60.1 (95% CI [35.3, 85.0]) at 12 months. The Freiburger Monosyllabic Test (FMT) and Consonant-Nucleus-Consonant (CNC) also improved significantly, with mean difference improvements of 46.2 (95% CI [30.0, 62.4]) for FMT and 19.3 (95% CI [8.1, 30.4]) for CNC. There was a statistically significant decrease in tinnitus, as measured by a mean difference reduction of 48.1 (95% CI [1.0, 95.2]) in the Tinnitus Handicap Index.

CONCLUSIONS

CoI with and without simultaneous labyrinthectomy is a viable treatment option for patients with MD, yielding high rates of tinnitus suppression and vertigo control. Post-CoI MD patients demonstrate similar postoperative speech perception outcomes to non-MD implant recipients. Laryngoscope, 131:1845-1854, 2021.

[The analysis of the characteristics of hearing loss in patients with cochlear nerve aphasia identified by MRI]

Objective:To explore the characteristics of hearing loss in patients with cochlear nerve aphasia（CNA） and to provide evidences for diagnosis and treatment of cochlear nerve aphasia. Methods:A retrospective study was performed. A total of 51 cases were included in the study. The data of hearing test, inner auditory canal MRI and temporal HRCT were analyzed. Results:77.19% of the affected ears had extremely severe hearing loss, and 7.02% of the affected ears had moderate hearing loss. The residual hearing was concentrated in low-medium frequency. A CNA ear with bone cochlear nerve canal atresia can exhibited moderate hearing loss. Conclusion:The patient with CNA may still present residual hearing function. CNA could not be excluded in patients with moderate hearing loss. The "three-dimensional integration" comprehensive evaluation system, which includesinternal auditory canal MRI, temporal thin-layer CT scan and audiology evaluation, could be helpful to the diagnosis of cochlear nerveaphasia.

Hearing and speech benefits of cochlear implantation in children: A review of the literature

Cochlear implantation is a safe and reliable treatment for children with severe to profound hearing loss. The primary benefit of these medical devices in children is the acquisition of hearing, which promotes development of spoken language. The present paper reviews published literature demonstrating predictive effects of a number of factors on acquisition of hearing development and speech recognition. Of the many variables that contribute to an individual child's development after implantation, age at implantation, the presence of medical comorbidities, social determinants of health, and the provision of bilateral versus unilateral hearing are those that can vary widely and have consistently shown clear impacts. Specifically, age of implantation is crucial to reduce effects of deafness on the developing auditory system and capture the remarkable plasticity of early development. Language development after cochlear implantation requires therapy emphasizing hearing and oral communication, education, and other support which can be influenced by known social determinants of health; specifically, outcomes in children decline with reductions in socioeconomic status and levels of parental education. Medical co-morbidities also slow rates of progress after cochlear implantation. On the other hand, benefits of implantation increase in children who are provided with access to hearing from both ears. In sum, cochlear implants promote development of hearing in children and the best outcomes are achieved by providing early access to sound in both ears. These benefits can be limited by known social determinants of health which restrict access to needed support and medical comorbidities which add further complexity in care and outcome.

Prognostic factors in cochlear implantation in adults: Determining central process integrity

The purpose of this study is to examine various preoperative factors that can play a role in the auditory rehabilitation outcome of cochlear implant (CI) recipients. In order to determine the level of integrity of central processing preoperatively, special attention was given to residual hearing, duration of deafness, and cochlear nerve diameter as prognostic factors. A cohort of 232 (272 CI implantations) postlingually deafened adults was evaluated in this study. Hearing results at 1, 2 and up to 3 years postoperatively were compared with various preoperative factors: promontory stimulation testing, residual hearing, duration of deafness, and magnetic resonance imaging of the cochlear nerve. Postoperative hearing performance was measured based on the German Freiburg monosyllabic word test and the Oldenburg sentence test. Postoperative hearing performance showed a significant improvement in each consecutive year after implantation. Duration of deafness showed a negative correlation to word recognition and a positive correlation to increased signal-to-noise-ratio in sentence testing. A significant decline in hearing outcome was shown starting around the second decade of deafness corresponding to 66% of life spent in deafness. MR imaging of cochlear nerve diameter shows a positive correlation of larger nerve diameter to better speech understanding. Promontory stimulation testing did not show any prognostic value. In this retrospective review it could be shown that there is an intricate interaction in the preoperative variables: duration of deafness - as well as the ratio of life spent in deafness; residual hearing; and cochlear nerve diameter.

A Ten-Year Review of Audiological Performance in Children with Inner Ear Abnormalities after Cochlear Implantation in Singapore

OBJECTIVES

To evaluate children with inner ear malformations following cochlear implantation (CI) in a tertiary pediatric hospital in Singapore to identify factors influencing outcomes after CI.

METHODS

This is a retrospective cohort study of children aged 0 to 18 years, who had CI between 2000 and 2013. Demographic information, data on risk factors, type of inner ear malformation (IEM), age at implantation, speech pre- and postimplantation, and duration of follow-up were collected from clinical records. Operative details and audiological outcomes were also analyzed.

RESULTS

A total of 70 children underwent 83 CI surgeries. The mean age of the patients was 4.05 ± 3.17 years (range 1-18 years). Twenty patients (28.57%) had abnormal CT scan findings. CSF gusher occurred in 15 out of 26 CI (57.69%) in the group with IEM. Nine out of twenty patients (45.00%) had poor IT-MAIS scores prior to implantation. The average preoperative IT-MAIS score for children with anomalous inner ear anatomy was 14.1. The older CI patients, 3/20 (15.00%), mean age 8.33 years (range 7-10 years), were mostly referred for persistently unclear speech following hearing aids. Eleven patients (55.00%) had good speech and aided hearing threshold within speech limits after CI and were eligible for reintegration into mainstream schools. Five patients (25.00%) had improvement in speech but continued to receive education in special schools. Four patients (20.00%) had poor progress after surgery.

CONCLUSION

The presence of absent cochlear nerve, electrode folding, and underlying neurological disorders seemed to be associated with poorer outcomes.

Hearing Restoration in Cochlear Nerve Deficiency: the Choice Between Cochlear Implant or Auditory Brainstem Implant, a Meta-analysis

OBJECTIVE

To answer the dilemma clinician's face when deciding between cochlear implant (CI) and auditory brainstem implant (ABI) treatment options in patients with cochlear nerve deficiency (CND).

STUDY DESIGN

Case study supplemented with literature review and meta-analysis.

SETTING

Tertiary referral center.

PATIENT(S)

Child with CHARGE syndrome and congenital deafness.

INTERVENTION(S)

ABI as there was no benefit after bilateral cochlear implantation.

MAIN OUTCOME MEASURES

Speech and language development, quality of life.

RESULTS

In one ear the cochleovestibular nerve was present on magnetic resonance imaging (MRI) without preoperative ABR responses. In the contra lateral ear the nerve could not be identified, despite present ABR responses. Nevertheless, there was no positive outcome with CI. The patient had improved speech and language and quality of life with ABI. Of the 108 patients with CND and CI identified in the literature review, 25% attained open-set speech perception, 34% attained closed-set speech perception, and 41% detected sounds or less. The appearance of the cochlear nerve on MRI was a useful predictor of success, with cochlear nerve aplasia on MRI associated with a smaller chance of a positive outcome post cochlear implantation compared with patients with cochlear nerve hypoplasia.

CONCLUSION

Although patients with (apparent) cochlear nerve aplasia are less likely to benefit from CI, CI before ABI is supported as some patients attain closed or open-set levels of speech perception after cochlear implantation.

Extremely common radiographic finding of cochlear nerve deficiency among infants with prelingual single-sided deafness and its clinical implications

OBJECTIVES

To clarify the common radiographic findings of audiologically documented prelingual single-sided deafness (SSD) and identify the prevalence of cochlear nerve deficiency (CND) in SSD infants referred from the newborn hearing screening program.

METHODS

Between March 2012 and March 2017, the records of all infants referred to our otology clinic after undergoing newborn hearing screening program were retrospectively reviewed. Twenty-four consecutive well infants without risk factors who had a confirmed diagnosis of prelingual SSD under the age of 1 year and who underwent internal auditory canal (IAC) magnetic resonance imaging (MRI) were included. The sizes of cochlear nerve (CN), IAC, and cochlear nerve canal (CNC) were measured on MRI. The presence of CND was visually determined by comparing the CN size to the ipsilateral facial nerve (FN) in the affected side via an oblique sagittal view of IAC MRI and defined when CN was absent or smaller than FN.

RESULTS

CND was seen in all 24 deaf ears (100%) on MRI. There was one with incomplete partition type I, and another with combined cochleovestibular nerve absence. Twenty-four subjects demonstrated either an absent (20/24, 83.3%) or small (4/24, 16.7%) CN. When the absent and small CN groups were compared, the former group had a higher prevalence of narrow CNC and narrow IAC. Of the 20 infants without identifiable CN on the affected side, 17 (85%) had narrow IAC and 17 (85%) had narrow CNC. In the 20 ears with absent CN, only one had both normal-sized IAC and CNC.

CONCLUSION

The contribution of CND to prelingual SSD in Korean infants reached 100%, according to IAC MRI alone.

Outcomes after cochlear implant provision in children with cochlear nerve hypoplasia or aplasia

INTRODUCTION

Cochlear nerve aplasia or hypoplasia is found in up to a half of patients with unilateral or bilateral hearing loss. There is an ongoing discussion regarding the indication of cochlear implants for hearing rehabilitation in cases with radiologically-defined aplasia or hypoplasia of the cochlear nerve in those patients, especially in children. At present there is conflicting evidence whether the audiological outcomes of those children with a CI are comparable to those of children with a CI and a radiologically-normal cochlear nerve. The primary aim of this study was to assess the audiological abilities before and after CI provision in children with cochlear nerve hypoplasia or aplasia. Additionally, we aimed to determine if audiological outcomes differed in children with aplasia from those with hypoplasia. Such data should be helpful in determining if CI provision is appropriate for such children.

METHODS

This retrospective study presents 7 children who were diagnosed with cochlear nerve aplasia or hypoplasia and received a CI. The pre- and postoperative audiological performance and the hearing and speech development of the children were examined.

RESULTS

4 children were unilateral CI users and 3 were bilateral CI users. Hearing reactions could be detected in all children. Already at first fitting, prompt responses and reactions to songs were observed. The aided thresholds in free field in children with hypoplasia were between 30 and 60 dB. Even in children with aplasia, the results in free field with CI averaged between 30 and 70 dB. Therefore the aided thresholds in children with hypoplasia and in children with aplasia of the CN are similar. It could be demonstrated that hearing reactions improve with the long term use of the implant. Improvement in general development could be observed in all children despite the very heterogeneous conditions and the accompanying handicaps.

CONCLUSION

The results of this study support the hypothesis that children with radiologically-defined CN hypoplasia or aplasia and detectable responses to electrical or acoustical stimuli can improve their sound detection thresholds and their awareness of sound when provided with a CI.

Does the Width of the Bony Cochlear Nerve Canal Predict the Outcomes of Cochlear Implantation?

A narrow bony cochlear nerve canal (BCNC) is associated with sensorineural hearing loss necessitating cochlear implantation (CI). This study evaluated the implications of BCNC width for post-CI outcomes. A total of 56 children who had received CIs were included. The patients were divided into three groups according to the width of the BCNC (Group 1: diameter < 1.4 mm, n = 17; Group 2: diameter 1.4-2.0 mm, n = 14; Group 3: diameter > 2.0 mm, n = 25). The post-CI speech performances were compared among the three groups according to BCNC width. The correlation between BCNC width and post-CI speech performance was evaluated. Logistic regression analysis was also performed to investigate factors that can impact post-CI speech performance. Cochlear nerve deficiency (CND) occurred more frequently in Group 1. Groups 1 and 2 had significantly worse post-CI outcomes. Patients with intact cochlear nerves had significantly better post-CI outcomes than those with CND. When the cochlear nerve was intact, patients with a narrower BCNC showed less favorable results. Therefore, patients with either a narrow BCNC or CND seemed to have poorer outcomes. A narrow BCNC is associated with higher CND rates and poor outcomes. Measurement of BCNC diameter may help predict CI outcomes.

Cochlear Implant Outcomes in Cochlea Nerve Aplasia and Hypoplasia

OBJECTIVE

To assess cochlear implant (CI) outcomes, and factors affecting outcomes, for children with aplasia/ hypoplasia of the cochlea nerve. We also developed a new grading system for the nerves of the internal auditory meatus (IAM) and cochlea nerve classification.

STUDY DESIGN

Retrospective patient review.

SETTING

Tertiary referral hospital and cochlear implant program.

PATIENTS

Children 0 to 16 years inclusive with a CI who had absent/hypoplastic cochlea nerve on magnetic resonance imaging (MRI).

INTERVENTION

Cochlear implant.

MAIN OUTCOME MEASURES

MRI, trans-tympanic electrical auditory brainstem response, intraoperative electrical auditory brainstem response, Neural Response Telemetry, Categories of Auditory Perception score, Main mode of communication.

RESULTS

Fifty CI recipients (26 males and 24 females) were identified, 21 had bilateral CIs, 27 had developmental delay. MRI showed cochlea nerve aplasia in 64 ears, hypoplasia in 25 ears, and a normal nerve in 11 ears. Main mode of communication was analyzed for 41 children: 21 (51%) used verbal language (15 speech alone, 5 speech plus some sign, 1 bilingual in speech and sign), and 20 (49%) used sign language (10 sign alone, 9 sign plus some speech, 1 tactile sign). Seventy-three percent of children used some verbal language. Cochlea nerve aplasia/ hypoplasia and developmental delay were both significant factors affecting main mode of communication. Categories of Auditory Performance scores were available for 59 CI ears; 47% with CN Aplasia (IAM nerve grades 0-III) and 89% with CN hypoplasia (IAM nerve grade IV) achieved Categories of Auditory Performance scores of 5 to 7 (some verbal understanding) (p = 0.003).

CONCLUSION

Our results are encouraging and useful when counselling families regarding the likelihood of language outcomes and auditory understanding.

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.

Bilateral cochlear nerve absence in a 3 year old child with VACTERL association

We report a case of a 3 year old boy with bilateral profound sensorineural hearing loss diagnosed from New Born Hearing Screening, with severe form of VACTERL association. He was referred to our Cochlear Implant Unit for assessment with regard to the possibility of cochlear implantation. MRI findings have showed bilateral vestibulocochlear cystic abnormalities. Only single nerve noted within the IAM on the right and likely single nerve within the IAM on the left. Hence, decision was made not to offer cochlear implantation. This is the first report of severe bilateral cochleovestibular nerve abnormalities to be associated with VACTERL.

Evaluation of cochlear nerve diameter and cross-sectional area in ANSD patients by 3.0-Tesla MRI

CONCLUSIONS

The size of cochlear nerve (CN) is atrophic in adult auditory neuropathy spectrum disorder (ANSD) patients compared with non-ANSD sensorineural hearing loss (SNHL) patients and normal hearing subjects, and CN deficiency is one of the lesions for ANSD patients.

OBJECTIVES

To evaluate the dimensions of CN in adult ANSD patients on magnetic resonance imaging (MRI) and confirm the hypothesis that CN deficiency is one of the lesions for ANSD patients.

METHODS

Medical records and MRI of 24 adult ANSD patients reviewed retrospectively and 20 non-ANSD SNHL and 24 volunteers with normal hearing were recruited as control groups. The long diameter (LD), short diameter (SD), and cross-sectional area (CSA) of CN and facial nerve (FN) were measured.

RESULTS

Among the 24 ANSD patients, this study was able to reconstruct and measure the CN of 91.7% (22/24, total 43 ears) of patients and FN of 83.3% (20/24, total 38 ears) of patients. The mean values and standard deviations of LD, SD, and CSA of CN in ANSD patients were 0.65 ± 0.20 mm, 0.44 ± 0.15 mm, and 0.30 ± 0.19 mm(2), respectively. They were significantly smaller in ANSD patients than in control groups (p < 0.001).

Neural Response Telemetry Thresholds in Patients with Cochlear Nerve Canal Stenosis

Objective

To explore neural response telemetry (NRT) thresholds in patients with stenotic versus normal cochlear nerve canals.

Study Design

Case series with chart review.

Setting

Tertiary referral center.

Subjects and Methods

Thirty pediatric patients with profound sensorineural hearing loss in at least 1 ear and no benefit from amplification underwent computed tomography imaging of the temporal bones. They were divided into 3 groups according to the diameter of the cochlear nerve canal: group A, <1.5 mm; group B, 1.5 to 1.7 mm; group C, 1.8 to 2.1 mm. All patients underwent cochlear implantation with full insertion of all electrodes. NRT was performed both intraoperatively and 6 months postoperatively in all patients; thresholds of electrodes 1, 11, and 22 were compared.

Results

Per analysis of variance, intraoperative and 6-month postoperative NRT thresholds were both significantly different among groups A, B, and C at electrodes 1 and 22 but not at electrode 11. On intergroup analysis, group A showed statistically higher thresholds than those of groups B and C; however, no difference was found between groups B and C.

Conclusion

Cochlear nerve canal stenosis, defined as a canal diameter <1.5 mm, is associated with significantly increased NRT thresholds, which may play a role in postimplant performance.

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

OBJECTIVES

The auditory brainstem implant (ABI) is an option for hearing rehabilitation in profoundly deaf patients ineligible for cochlear implantation. Over the past decade, surgeons have begun implanting ABIs in pediatric patients who are unable to receive cochlear implants due to congenital or acquired malformations of the inner ear. No study has examined the potential population-level demand for ABIs in the United States (US). Herein, we aim to quantify the potential need for pediatric ABIs.

METHODS

A systematic literature review was conducted to identify studies detailing the rates of congenital cochlear and/or cochlear nerve (CN) anomalies. Absolute indications for ABI include bilateral cochlea or CN aplasia (Group A), and relative indications for ABI include bilateral cochlea or CN hypoplasia (Group B). Data was subsequently correlated to the US Census Bureau, the National Health Interview Survey, and the Gallaudet Research Institute to provide an estimation of pediatric ABI candidates.

RESULTS

Eleven studies documented rates of bilateral findings. Bilateral cochlea aplasia was identified in 0-8.7% of patients and bilateral CN aplasia in 0-4.8% of patients (Group A). Bilateral cochlea hypoplasia was identified in 0-8.7% of patients and bilateral CN hypoplasia in 0-5.4% of patients (Group B). Using population-level sensorineural hearing loss data, we roughly estimate 2.1% of potential implant candidates meet absolute indications for an ABI in the United States.

CONCLUSION

Congenital cochlear and cochlear nerve anomalies are exceedingly rare. This study provides the first preliminary estimate of cochlea and CN aplasia/hypoplasia at the population level albeit with limitations based on available data. These data suggest the need for dedicated ABI centers to focus expertise and management.

Cochlear implantation in children with cochlear nerve deficiency

OBJECTIVE

The aim of this study was to report on auditory performance after cochlear implantation in children with cochlear nerve deficiency.

METHODS

A retrospective case review was performed. Five patients with pre-lingual profound sensorineural hearing loss implanted in an ear with cochlear nerve deficiency participated in the study. Postoperative auditory and speech performance was assessed using warble tone average threshold with cochlear implant, speech perception categories, and speech intelligibility ratings. All patients underwent high resolution computed tomography and magnetic resonance imaging.

RESULTS

According to Govaerts classification, three children had a type IIb and two a type IIa cochlear nerve deficiency. Preoperatively, four patients were placed into speech perception category 1 and one into category 2. All patients had an improvement in hearing threshold with the cochlear implant. Despite this, at the last follow-up (range 18-81 months, average 45 months), only one girl benefited from cochlear implantation; she moved from speech perception category 2 to 6 and developed spoken language. Another child developed closed set speech perception and had connected speech that was unintelligible. The other 3 children showed little benefit from the cochlear implant and obtained only an improved access to environmental sounds and improved lipreading skills. None of these 4 children developed a spoken language, but they were all full-time users of their implants.

CONCLUSIONS

The outcomes of cochlear implantation in these five children with cochlear nerve deficiency are extremely variable, ranging from sporadic cases in which open set speech perception and acquisition of a spoken language are achieved, to most cases in which only an improved access to environmental sound develops. Regardless of these limited outcomes, all patients in our series use their device on a daily basis and derive benefits in everyday life. In our opinion, cochlear implantation can be a viable option in children with cochlear nerve deficiency, but careful counseling to the family on possible restricted benefit is needed.

The Therapeutic Dilemma of Cochlear Nerve Deficiency

Objective

To compare the outcomes between 2 age-matched cohorts of children with cochlear nerve deficiency: those receiving auditory brainstem implants (group A) or cochlear implants (group B).

Study Design

Retrospective cohort study.

Setting

Tertiary referral center.

Subjects and Methods

Subjects were selected from a pool of 537 children fitted with cochlear implants (n = 443) or auditory brainstem implants (n = 94) over the past 14 years. Performance, examined with the Category of Auditory Performance scale, and complications were compared with a mean follow-up of 5 years.

Results

All children had bilateral profound sensorineural hearing loss and cochlear nerve deficiency. Magnetic resonance imaging documented an absent cochlear nerve (n = 12) and a small cochlear nerve (n = 8) in group A and an absent cochlear nerve (n = 11) and a small cochlear nerve (n = 9) in group B ( P = 1.000). Children with cochlear implants had Category of Auditory Performance scores spanning from 0 to 3 levels of performance, and all required manual communication mode and visual supplementation. Children with auditory brainstem implants had Category of Auditory Performance scores spanning from 2 to 7, and most patients demonstrated behavioral responses irrespective of inner ear malformations and an absent cochlear nerve or small cochlear nerve ( P < .001).

Conclusions

In children with cochlear nerve deficiency, patients fitted with cochlear implants did not develop speech understanding and production. Those fitted with auditory brainstem implants had the opportunity to develop open-set speech perception, acquiring verbal language competence using oral communication exclusively and participating in mainstream education. The overall complication rate of auditory brainstem implants was not greater than that of cochlear implants.

Cochlear implantation for a child with cochlear nerve deficiency: parental perspectives explored through narrative

OBJECTIVE

The objective of this study was to explore, from the parents' perspectives, decision-making regarding a cochlear implant (CI) for their child when a favourable outcome is less likely because of abnormal neurophysiology.

DESIGN

The primary research method of this single case study was qualitative interviewing drawing on a narrative approach to elicit the parents' perspectives about their experiences over time. Each parent was interviewed separately, but thematic analyses were undertaken both within and across interviews in order to identify overlaps and differences.

STUDY SAMPLE

Participants included the parents of a five-year old child with severe-profound hearing loss, cochlear nerve deficiency, and bilateral common cavities who had received a CI at the age of 18 months.

RESULTS

Four themes were identified across the four narrative stages that emerged from the parents' accounts of their experiences regarding their daughter's CI. Themes included hope and despair, questioning professionals' motivations, does deafness need a cure, and bringing the child into the family. Although these themes emerged from both parents' accounts, each parent expressed different perspectives and insights within them.

CONCLUSIONS

Findings highlight the central place of parental needs and perspectives in decision-making regarding a CI, particularly in the context of uncertain outcomes.

Unilateral cochlear nerve deficiency in children

OBJECTIVE

Cochlear nerve deficiency (CND) is increasingly diagnosed in children with sensorineural hearing loss (SNHL). We sought to determine the prevalence of CND, its imaging characteristics, and correlations with audiologic phenotype in children with unilateral SNHL.

DESIGN

Case series with chart review.

SETTING

Tertiary pediatric hospital.

SUBJECTS/METHODS

In 128 consecutive children with unilateral SNHL who underwent high-resolution magnetic resonance imaging, the diameters, area, and signal intensity of the cochlear nerve (CN) were measured and normalized to the ipsilateral facial nerve. Presence of CND was determined by comparison to normative data. Relationships among hearing loss severity, progression, and nerve size were investigated.

RESULTS

Cochlear nerve deficiency was present in 26% of children with unilateral SNHL. Its prevalence was higher (48%) in severe to profound SNHL, especially when in infants (100%). Width of the bony cochlear nerve canal (BCNC) correlated strongly with relative CN diameter, density, and area (R = 0.5); furthermore, a narrow BCNC (<1.7 mm) strongly predicted CND. Severity of hearing loss modestly correlated with nerve size, although significant variability was observed. Progression never occurred unless there were other inner ear malformations, whereas in the non-CND group, it occurred in 22%. Ophthalmologic abnormalities were very common (67%) in CND children, particularly oculomotor disturbances.

CONCLUSION

Cochlear nerve deficiency is a common cause of unilateral SNHL, particularly in congenital unilateral deafness. Width of the BCNC effectively predicts CND, a finding useful when only computed tomography imaging is available. In an ear with CND, hearing can be expected to remain stable over time. Diagnosis should prompt evaluation by an ophthalmologist.

Cochlear implantation after selective vestibular nerve section

Introduction:

Vestibular nerve section is a highly effective procedure for the control of vertigo in patients with Ménière's disease. However, hearing loss is a possible complication. If hearing loss occurs after vestibular nerve section, magnetic resonance imaging should make it possible to establish the presence or absence of an intact cochlear nerve.

Method:

Case report and review of the world literature concerning cochlear implantation after vestibular nerve section.

Case report:

We present a patient who developed subtotal hearing loss after vestibular nerve section. Magnetic resonance imaging was used to verify the presence of an intact cochlear nerve, enabling successful cochlear implantation.

Conclusion:

To our knowledge, this is the first reported case of cochlear implantation carried out after selective vestibular nerve section. Given recent advances in cochlear implantation, this case indicates that it is essential to make every effort to spare the cochlear nerve if vestibular nerve section is required. If hearing loss occurs after vestibular nerve section, magnetic resonance imaging should be undertaken to establish whether the cochlear nerve is intact.

Pediatric cochlear implantation of children with eighth nerve deficiency

OBJECTIVE

To evaluate the auditory outcomes of children implanted in an ear with eighth nerve hypoplasia or aplasia and to determine whether preoperative characteristics are predictive of auditory performance achieved.

STUDY DESIGN

retrospective case review.

SETTING

tertiary care medical center.

PATIENTS

ten children implanted in an ear with eighth nerve hypoplasia or aplasia, as determined by high resolution magnetic resonance imaging.

MAIN OUTCOME MEASURES

Neural response test measurements, detection and speech awareness thresholds, Meaningful Auditory Integration Scale scores, as well as speech perception level achieved.

RESULTS

Post-implantation, three children demonstrated little to no detection of sound, three had improved detection and awareness of environmental sounds, one developed closed-set speech perception and spoken language, and three developed open-set speech perception and spoken language. No imaging findings appeared related to outcomes. Significantly better implant detection thresholds and Meaningful Auditory Integration Scale scores were found in children who had preoperative aided auditory detection (p's ≤ 0.02-0.05).

CONCLUSION

Some children with eighth nerve hypoplasia or aplasia may derive significant benefit from a cochlear implant. In our study high resolution magnetic resonance imaging was more sensitive than high resolution computer tomography in detecting neural deficiency. However, no imaging findings were predictive of auditory performance level achieved post-implantation.

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.

Assessment of cochlear implant candidacy in patients with cochlear nerve deficiency using the P1 CAEP biomarker

OBJECTIVE

The goal of this report was to ascertain the efficacy of the P1 cortical auditory evoked potential (CAEP) biomarker as an objective tool to assist in the evaluation of cochlear implant (CI) candidacy in children with a radiological diagnosis of cochlear nerve deficiency (CND).

METHODS

Retrospective case study review of audiological and radiological findings was performed in four pediatric patients identified with CND and severe-to-profound sensorineural hearing loss. Cortical auditory evoked potential testing was conducted, and the presence and latency of the P1 component were analyzed.

RESULTS

Three out of four children demonstrated robust P1 CAEP responses, indicating activation of the central auditory pathways by auditory stimulation, despite the diagnosis of CND. These children were considered good candidates for cochlear implantation.

DISCUSSION

Although cochlear implantation in children is a fairly routine procedure, cases exist for which implant candidacy is questionable. Among these cases are children with CND. In these children, cochlear implantation may be contraindicated due to the likelihood that the implant electrodes may not stimulate the VIII nerve adequately. Magnetic resonance imaging (MRI) is considered the gold standard in the assessment of CND, but this measure is not always sufficient to determine CI candidacy in cases of CND. The addition of the P1 CAEP measurement to the usual electrophysiological, audiometric, and radiological test battery may prove to be useful in determining CI options for children with CND.

Normative diameters and effects of aging on the cochlear and facial nerves in normal-hearing Korean ears using 3.0-tesla magnetic resonance imaging

OBJECTIVES/HYPOTHESIS

To assess the normative size of the cochlear nerve (CN) and facial nerve (FN) in normal-hearing ears and to determine whether nerve size varies with age.

STUDY DESIGN

Cross-sectional.

METHODS

We included 169 ears with normal hearing between 2005 and 2010. The height, width, and cross-sectional area (CSA) of the CN and FN in the middle of the internal auditory canal were measured on oblique sagittal images of 3.0-T magnetic resonance imaging. Results were compared by age. Young subjects were divided into three age groups, 0-5, 6-10, and 11-15 years. Subjects over age 40 years were divided into groups at 10-year intervals.

RESULTS

Mean age was 32.6 years (range, 0.75-79 years). We found that the CN had significantly greater vertical (1.10 ± 0.21 mm vs. 0.95 ± 0.21 mm) and horizontal (1.11 ± 0.20 mm vs. 1.03 ± 0.22 mm) diameters than the FN. The CSA of the CN was larger than that of the FN (0.98 ± 0.33 mm(2) vs. 0.79 ± 0.31 mm(2) ). Except for the CN vertical diameter, there were no significant differences between right and left ears. Sex did not affect the nerve size. Although the CN was not affected by age, the FN vertical diameter and CSA of children <5 years were significantly smaller than those of children aged >5 years. The size of the two nerves did not differ among groups over age 40 years.

CONCLUSIONS

The CN is not affected by age in normal-hearing ears. The FN vertical diameter and CSA of children <5 years are smaller than those of older children.

Cochlear implantation in children with cochlear nerve absence or deficiency

OBJECTIVE

To evaluate speech perception after cochlear implantation in children with cochlear nerve absence or deficiency.

METHODS

A retrospective case review was performed to identify children who underwent cochlear implantation with cochlear nerve absence or deficiency. The cochlear nerve was evaluated by high-resolution three-dimensional T2-weighted fast spin echo MR in the oblique sagittal and axial planes. A deficient cochlear nerve was defined as a cochlear nerve that is smaller in diameter when compared with the adjacent facial nerve in the midportion of the internal auditory canal. The cochlear nerve was considered absent if there was no imaging evidence of a cochlear nerve. Speech awareness threshold and the speech perception category score were used to measure speech perception after cochlear implantation.

RESULTS

Seven children who underwent cochlear implantation in an ear without imaging evidence of a cochlear nerve were identified. One child developed early closed-set speech recognition. The other 6 children developed only speech detection or pattern perception. Two children underwent cochlear implantation with a deficient cochlear nerve. One developed consistent closed-set word recognition and the other developed early closed-set word recognition. The mean follow-up time for all patients was 3.8 years (range, 1.1-7.1 yr).

CONCLUSION

Cochlear nerve deficiency is not an uncommon cause for profound sensorineural hearing loss and presents a challenge in the decision-making process regarding whether to proceed with a cochlear implant. Children with a deficient but visible cochlear nerve on magnetic resonance image can expect to show some speech understanding after cochlear implantation; however, these children do not develop speech understanding to the level of implanted children with normal cochlear nerves. Children with an absent cochlear nerve determined by magnetic resonance imaging can be expected to have limited postimplantation sound and speech awareness.

Bilateral implantation in children with cochleovestibular nerve hypoplasia

To report on the outcomes of sequential bilateral cochlear implantation (CI) in children with inner ear malformation. The study design is a retrospective case study. The setting is a tertiary reference center. Two children presenting a profound bilateral congenital hearing loss with bilateral hypoplasia of the cochleovestibular nerves and hypoplasic external semicircular canal had a cochlear implant at respectively 16 months and 33 months. A second implant was proposed at respectively 17 and 20 months after the first implant. The main outcome measures are audiometry, perceptive results in closed and open set words (CSW and OSW) and oral production at follow-up. The first cochlear implant gave respectively mean thresholds at 60 dB and 70 dB. Bilateral CI showed mean threshold at respectively 40 dB and 55 dB. In case 1, perceptive assessment was 83% and 70% in respectively CSW and OSW with oral production and comprehension of sentences after 1 year follow-up. In case 2, the perceptive assessment showed no perceptive or linguistic evolution at 6 months follow-up. In cochleovestibular nerve hypoplasia, bilateral implantation could be discussed in cases of limited result after unilateral implant.