Proportion of bony cochlear nerve canal anomalies in unilateral sensorineural hearing loss in children

High Prevalence of Cochlear Nerve Deficiency in Pediatric Patients With Cochlear Aperture Stenosis

OBJECTIVE

Cochlear nerve deficiency (CND) is a common radiologic finding among unilateral sensorineural hearing loss (USNHL) patients. It is generally detected with magnetic resonance imaging (MRI), which is associated with higher cost, less availability, and possible need for sedation. Therefore, identifying computed tomography (CT) findings, such as cochlear aperture stenosis (CAS), that can reliably predict CND is valuable. Our study aimed to determine the prevalence of CND in pediatric patients with CT-diagnosed CAS.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary care center.

METHODS

We included pediatric patients diagnosed with CAS on temporal bone CT and with available temporal bone MRI. For each patient, an otolaryngologist and a pediatric neuroradiologist measured the cochlear aperture width on CT to confirm CAS (cochlear aperture < 1.4 mm) and assessed the status of the cochlear nerve on MRI.

RESULTS

Fifty-five patients, representing 65 ears, had CAS on CT measurement. Median cochlear aperture width in CAS ears was 0.70 mm (interquartile range [IQR]: 0.40-1.05 mm) versus 2.00 mm in non-CAS ears (IQR: 1.80-2.30 mm, P < .001). CND was found in 98.5% (n = 64/65) of CAS ears, while a normal cochlear nerve was found in 1.5% (n = 1/65) of CAS ears.

CONCLUSION

CND is highly prevalent among pediatric patients with CAS. This suggests that MRI may not be needed to assess for CND in USNHL patients with CAS, as initial CT may provide sufficient information to determine cochlear implant candidacy. We recommend thoughtful shared decision-making with parents of USNHL patients when determining whether to pursue MRI in the setting of a CAS diagnosis.

Electrically evoked auditory brainstem responses in deaf children with cochlear nerve canal stenosis

BACKGROUND

Deaf children with cochlear nerve canal stenosis (CNCs) are always considered poor candidates for cochlear implantation.

OBJECTIVES

To investigate the function of the peripheral auditory pathway in deaf children with CNCs, as revealed by the electrically evoked auditory brainstem response (EABR), and postoperative cochlear implants (CIs) outcomes.

MATERIALS AND METHODS

Thirteen children with CNCs and 13 children with no inner ear malformations (IEMs) who received CIs were recruited. The EABR evoked by electrical stimulation from the CI electrode was recorded. Postoperative CI outcomes were assessed using Categories of Auditory Performance (CAP) and Speech Intelligibility Rate (SIR).

RESULTS

Compared with children with no IEMs, children with CNCs showed lower EABR extraction rates, higher thresholds, a longer wave V (eV) latency and lower CAP and SIR scores. The auditory and speech performance was positively correlated with the diameter of the cochlear nerve canal and the number of channels showing wave III (eIII) and eV in children with CNCs.

CONCLUSIONS AND SIGNIFICANCE

The physiological function of the peripheral auditory pathway in children with CNCs is poorer than that in children with no IEMs. Postoperative auditory and speech abilities may depend on the severity of cochlear nerve malformation and auditory conduction function.

Anatomical Features of Children With Mondini Dysplasia: Influence on Cochlear Implantation Performance

OBJECTIVE

To analyze the long-term auditory performance after cochlear implantation (CI) and identify anatomical features of Mondini dysplasia associated with post-CI outcomes.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary care academic center.

PATIENTS

We enrolled 49 ears with Mondini dysplasia who underwent CI with more than 7 years of follow-up and age at CI- and sex-matched control group with radiologically normal inner ears.

MAIN OUTCOMES AND MEASURES

The development of auditory skills after CI was evaluated using word recognition scores (WRSs). The anatomical features were measured based on temporal bone computed tomography and magnetic resonance imaging, involving the width of the bony cochlear nerve canal (BCNC), cochlear basal turn, enlarged vestibular aqueduct, cochlear height, and diameter of the cochlear nerve (CN).

RESULTS

CI in ears with Mondini dysplasia showed comparable benefits and improvement of auditory performance to controls during the 7 years of follow-up. In Mondini dysplasia, four (8.2%) ears showed narrow BCNC (<1.4 mm) with poorer WRS (58 ± 17%) than those with normal-sized BCNC, which had WRS (79 ± 10%) comparable to that of the control group (77 ± 14%). In Mondini dysplasia, the maximum ( r = 0.513, p < 0.001) and minimum ( r = 0.328, p = 0.021) CN diameters had positive correlations with post-CI WRS. The maximum CN diameter ( β = 48.347, p < 0.001) and BCNC width ( β = 12.411, p = 0.041) were significant factors that influence the post-CI WRS in multiple regression analysis.

CONCLUSIONS

Preoperative anatomical evaluation, especially BCNC status and CN integrity, may serve as predictive markers for post-CI performance.

The effect of bony cochlear nerve canal (BCNC) diameter on the degree of sensorineural hearing loss

PURPOSE

This study investigated the correlation between the diameter of the bony cochlear nerve canal (BCNC), as determined by Temporal bone CT, and MRI findings of cochlear nerves (CN) in children with sensorineural hearing loss (SNHL).

MATERIALS AND METHODS

A prospective study design was followed. Radiological data (Temporal bone CT and MRI) of fifty children with sensorineural hearing loss (age <18 y) were included in the study. All patients (100 ears) underwent routine MRI protocol in addition to 3D CISS (3-D constructive interference in steady state).

RESULTS

Based on CT findings, the BCNC was classified according to its diameter into three groups; group 1 (<1.4 mm), group 2 (1.4-2.0 mm), and group 3 (>2.0 mm). A significant difference between the three groups at degrees of SNHL (p < 0.001) was observed. Significant difference (p < 0.001) was also observed in the mean level of pure tone audiometry (PTA) average in group 1 compared to group 2. The CN was absent in 20 ears of group 1 CT results (29%), CN hypoplasia was noticed in 40 ears of group 1 CT (58%). However, CN was present in 9 ears of group 1 CT (13%), while in group 2 and 3, CN was present in 100% of the cases (27, and 4 ears, respectively, p < 0.001).

CONCLUSIONS

MRI and CT imaging are valuable in the diagnosis of SNHL in children. Moreover, with BCNC stenosis, there was a high probability of CN aplasia or hypoplasia.

[Cochlear nerve canal stenosis: a review of recent research]

Some patients with severe-profound sensorineural hearing loss （SNHL） with normal cochlear anatomical structure received cochlear implantation （CI） and the hearing and speech rehabilitation effect was not ideal. Through retrospective analysis, it was found that some of these patients had cochlear never canal （CNC） stenosis, or atresia in severe cases.This article reviews the development of the CNC, the diagnostic criteria of CNC stenosis and the results of hearing and speech rehabilitation in these patients after CI.

Clinical characteristics in unilateral cochlear nerve canal stenosis

OBJECTIVE

To characterize the clinical features of patients with congenital hearing loss and unilateral cochlear nerve canal stenosis (CNCS).

METHODS

A retrospective review of 12 patients with unilateral CNCS diagnosed between January 2018 and December 2019 at a tertiary referral hospital was performed.

RESULTS

Of the 12 patients identified, there were 6 males and 6 females. All patients presented with hearing loss, with no other chief complaints. Two patients had accessory auricles. Eleven patients had a severe to profound sensorineural hearing loss on the affected side, while 1 patient had an isolated high-frequency hearing loss. Nine patients demonstrated atresia of the cochlear nerve canal (CNC), while three patients had a stenotic, but patent, CNC.

CONCLUSION

Prompt radiologic diagnosis of patients with unilateral CNCS is important for patient counseling and appropriate rehabilitation.

Successful Use of a Cochlear Implant in a Patient with Bony Cochlear Nerve Canal Atresia

The anatomical cause of congenital sensorineural hearing loss can be atresia of the bony cochlear nerve canal (BCNC). It has been reported that the cochlear nerve (CN) can be either hypoplastic or aplastic when the BCNC width is <1.5 mm radioanatomically. It is difficult to estimate the auditory-verbal abilities after cochlear implantation (CI) in patients with a hypoplastic CN. In such cases, it is also challenging to decide on the best treatment modality: CI or auditory brainstem implantation. In this case report, we present a 4-year-old male patient with BCNC atresia and the successful use of a cochlear implant; we also discussed the importance of audiological evaluation. A detailed radiological evaluation must be performed in every case following electrophysiological studies prior to CI. To accurately diagnose the pathology and select the surgical side, both computed tomography and magnetic resonance imaging scans should be used as complementary imaging methods in all CI candidates.

Correlation of cochlear aperture stenosis with cochlear nerve deficiency in congenital unilateral hearing loss and prognostic relevance for cochlear implantation

The use of neonatal hearing screening has enabled the identification of congenital unilateral sensorineural hearing loss (USNHL) immediately after birth, and today there are several intervention options available to minimize potential adverse effects of this disease, including cochlear implantation. This study aims to analyze the characteristics of the inner ear of a homogeneous group of congenital non-syndromic USNHL to highlight the features of the inner ear, which can help in clinical, surgical, and rehabilitative decision-making. A retrospective chart review was carried out at a tertiary referral center. Systematic diagnostic work-up and rigorous inclusion-exclusion criteria were applied to 126 children with unilateral hearing impairment, leading to a selection of 39 strictly congenital and non-syndromic USNHL cases, undergoing computed tomography (CT) and magnetic resonance (MR) imaging studies. The frequency and type of malformations of the inner ear in USNHL and unaffected contralateral ears were assessed, with an in-depth analysis of the deficiency of the cochlear nerve (CND), the internal auditory canal (IAC) and the cochlear aperture (CA). Inner ear anomalies were found in 18 out of 39 (46%) of the USNHL patients. In 1 subject, the anomalies were bilateral, and the CND resulted in the predominant identified defect (78% of our abnormal case series), frequently associated with CA stenosis. Only 3 out of 14 children with CND presented stenosis of the IAC. CND and CA stenosis (and to a much lesser extent IAC stenosis) are a frequent association within congenital and non-syndromic USNHL that could represent a distinct pathological entity affecting otherwise healthy infants. In the context of a diagnostic work-up, the evaluation with CT and MRI measurements should take place in a shared decision-making setting with thorough counseling. Both imaging techniques have proven useful in differentiating the cases that will most likely benefit from the cochlear implant, from those with potentially poor implant performance.

Prevalence & features of inner ear malformations among children with congenital sensorineural hearing loss: A Public Cochlear Implant Centre Experience

OBJECTIVE

To determine the prevalence and features of inner ear anomalies in children with congenital profound hearing loss who presented at our cochlear implant center based on imaging studies.

METHODS

This retrospective study reviewed charts of children with congenital SNHL, who presented to Department of Otolaryngology & Auditory Implant Centre, Capital Hospital Islamabad over a period of 2 years from 1^st May 2017 to 30^th April 2019. These included 481 cases of both genders aged between 1 to 12 years. After gathering demographic data, audiological data, computed tomography findings of the temporal bone were analyzed. Data was analyzed using SPSS 22.

RESULTS

The Inner Ear Malformations were identified in 48(10%) children including 28 (58.33%) males and 20 (41.67%) female. Most 20(41.67%) presented at >3-5 years of age followed by 19(39.58%) at 2-3 years. However, no significant association of gender (p=0.57, p=0.076) and age of presentation (p=0.344, p=0.697) for right and left ears was noted with inner ear malformations. The most common anomaly noted were CLA, CH-III and CH-II in decreasing order of frequency in both ears.

CONCLUSION

The prevalence of IEM's was found to be 48(10%). Commonest anomalies noted were CLA, CH-III and CH-II. No significant association of gender and age of presentation was noted with type of anomaly in both ears.

Pre- and post-operative imaging of cochlear implants: a pictorial review

Cochlear implants are increasingly used to treat sensorineural hearing disorders in both children and adults. Pre-operative computed tomography and magnetic resonance imaging play a pivotal role in patient selection, to rule out findings that preclude surgery or identify conditions which may have an impact on the surgical procedure. The post-operative position of the electrode array within the cochlea can be reliably identified using cone-beam computed tomography. Recognition of scalar dislocation, cochlear dislocation, electrode fold, and malposition of the electrode array may have important consequences for the patient such as revision surgery or adapted fitting.

Cochlear nerve canal stenosis and associated semicircular canal abnormalities in paediatric sensorineural hearing loss: a single centre study

OBJECTIVE

This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis.

METHOD

This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated.

RESULTS

Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent).

CONCLUSION

Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

Inner-ear malformations as a cause of single-sided deafness

OBJECTIVE

To determine the prevalence and distribution of inner-ear malformations in congenital single-sided deafness cases, as details of malformation type are crucial for disease prognosis and management.

METHODS

A retrospective study was conducted of 90 patients aged under 16 years with congenital single-sided deafness. Radiological findings were evaluated using computed tomography and magnetic resonance imaging. Inner-ear malformations were identified and cochlear nerve status was determined in affected ears.

RESULTS

Out of 90 ears, 42 (46.7 per cent) were found to have inner-ear malformation. Isolated cochlear aperture stenosis was the most common anomaly (n = 18, 20 per cent), followed by isolated cochlear aperture atresia (n = 11, 12.2 per cent) and cochlear hypoplasia (n = 7, 7.8 per cent). Cochlear nerve deficiency was encountered in 41 ears (45.6 per cent). The internal auditory canal was also stenotic in 49 ears (54.4 per cent).

CONCLUSION

Inner-ear malformations, especially cochlear aperture anomalies, are involved in the aetiology of single-sided deafness more than expected. The cause of single-sided deafness differs greatly between congenital and adult-onset cases. All children with single-sided deafness should undergo radiological evaluation, as the prognosis and management, as well as the aetiology, may be significantly influenced by inner-ear malformation type.

Assessment of the Clinical Benefit of Imaging in Children With Unilateral Sensorineural Hearing Loss: A Systematic Review and Meta-analysis

Importance

Imaging used to determine the cause of unilateral sensorineural hearing loss (USNHL) in children is often justified by the high likelihood of detecting abnormalities, which implies that these abnormalities are associated with hearing loss and that imaging has a positive contribution to patient outcome or well-being by providing information on the prognosis, hereditary factors, or cause of hearing loss.

Objectives

To evaluate the diagnostic yield of computed tomography (CT) and magnetic resonance imaging (MRI) in children with isolated unexplained USNHL and investigate the clinical relevance of these findings.

Evidence Review

Cochrane Library, Embase, PubMed, and Web of Science databases were searched for articles published from 1978 to 2017 on studies of children with USNHL who underwent CT and/or MRI of the temporal bone. Two authors (F.G.R. and E.N.B.P.) independently extracted information on population characteristics, imaging modality, and the prevalence of abnormalities and assessed the studies for risk of bias. Eligibility criteria included studies with 20 or more patients with USNHL who had CT and/or MRI scans, a population younger than 18 years, and those published in English.

Main Outcomes and Measures

The pooled prevalence with 95% CI of inner ear abnormalities grouped according to finding and imaging modality.

Findings

Of 1562 studies, 18 were included with a total of 1504 participants included in the analysis. Fifteen studies were consecutive case studies and 3 were retrospective cohort studies. The pooled diagnostic yield for pathophysiologic relevant findings in patients with unexplained USNHL was 37% for CT (95% CI, 25%-48%) and 35% for MRI (95% CI, 22%-49%). Cochleovestibular abnormalities were found with a pooled frequency of 19% for CT (95% CI, 14%-25%) and 16% for MRI (95% CI, 7%-25%). Cochlear nerve deficiency and associated cochlear aperture stenosis had a pooled frequency of 16% for MRI (95% CI, 3%-29%) and 44% for CT (95% CI, 36%-53%), respectively. Enlarged vestibular aqueduct (EVA) was detected with a pooled frequency of 7% for CT and 12% for MRI in children with USNHL.

Conclusions and Relevance

Imaging provided insight into the cause of hearing loss in a pooled frequency of about 35% to 37% in children with isolated unexplained USNHL. However, none of these findings had therapeutic consequences, and imaging provided information on prognosis and hereditary factors only in a small proportion of children, namely those with EVA. Thus, there is currently no convincing evidence supporting a strong recommendation for imaging in children who present with USNHL. The advantages of imaging should be carefully balanced against the drawbacks during shared decision making.

Outcome of Cochlear Implantation in Children With Narrow Bony Cochlear Nerve Canal

OBJECTIVE

To investigate the diameter of the bony cochlear nerve canal (BCNC) as a prognostic indicator of cochlear implantation (CI) in children.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Two hundred ninety two prelingual deaf children (323 ears) who received CI before the age of 5 years.

INTERVENTIONS

CI in pediatric patients.

MAIN OUTCOME AND MEASURES

Postoperative auditory performance was analyzed according to the diameter of the BCNC using the Mann-Whitney U test. Using the images of temporal bone computed tomography, patients were grouped according to the diameter of the BCNC: narrow (<1.4 mm, Group 1), normal (Group 2), and other anomalies (Group 3).

RESULTS

Group 1 (10.5%) showed a less significant degree of improvement in category of audiological performance (CAP) score than Groups 2 (57.3%) and 3 (32.2%). Scores obtained from both the open-set monosyllabic words and sentence tests were lower in Group 1 than Groups 2 and 3. Of the patients with narrow BCNC, the CAP score of patient with complete stenosis of BCNC (<0.2 mm) was lower than that of patients with BCNC between 0.2 and 0.8 mm, also 0.8 and 1.4 mm.

CONCLUSIONS

The improvement in auditory performance was limited in children with narrow BCNC and the narrower the BCNC, the more severe the limitation. However, gradual improvement can be expected and even children with narrow BCNC may be candidates for early CI and rehabilitation.

Clinical Value of Measurement of Internal Auditory Canal in Pediatric Cochlear Implantation

OBJECTIVES

The aims of this study were to clarify the clinical value of the bony cochlear nerve canal (BCNC) and internal auditory canal (IAC) in children with bilateral sensorineural hearing loss (b-SNHL) and to reveal the correlation between these parameters and outcomes after cochlear implantation (CI).

METHODS

Ninety-four ears with b-SNHL that received CI and 100 ears with normal hearing were enrolled. Parameters of IAC and pre- and post-CI categories of auditory performance scores were analyzed.

RESULTS

The width of the BCNC and the width, height, and length of the IAC were shorter in the b-SNHL group. BCNC and IAC width were associated with b-SNHL. The calculated cutoff values for BCNC and IAC width were 2.055 mm in the BCNC and 4.245 mm in the IAC, setting the sensitivity to 90%. Patients with narrow BCNCs and IACs had significantly worse post-CI auditory performance.

CONCLUSIONS

BCNC and IAC widths were narrower in children with b-SNHL than in normal-hearing children. Narrow BCNC and IAC width had a negative impact on post-CI outcomes. The proposed cutoff values for BCNC and IAC width were meaningful when predicting the auditory outcome after CI, especially considering both.

A Predictive Model for Cochlear Implant Outcome in Children with Cochlear Nerve Deficiency

The outcome of cochlear implantation (CI) in patients with cochlear nerve deficiency (CND) is variable, resulting in a wide range of speech perception performance, from degrees of environmental sound perception to conversation without lip-reading. Twenty-five cochlear implantees with CND were enrolled retrospectively to determine the factors correlated with CI outcome in patients with CND and to develop a predictive model for CI outcome. CI outcome was evaluated using the Categories of Auditory Performance (CAP) score at 2 years after CI. Patients with negative auditory brainstem response (ABR) showed a significantly lower CAP score than those with positive ABR (2.5 ± 1.7, 4.8 ± 0.7; p = 0.001). The area ratio of vestibulocochlear nerve (VCN) to facial nerve (FN) at the cerebellopontine angle on magnetic resonance images was positively correlated with CI outcome (p < 0.001). With multiple regression analysis, a predictive equation accounting for 66% of variance of CAP score at 2 years after CI was \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\bf{deduced}}:{\bf{CAP}}\,{\bf{score}}{\boldsymbol{=}}{\bf{0.7}}{\boldsymbol{+}}{\bf{1.9}}{\boldsymbol{\ast }}{\boldsymbol{(}}{\bf{ABR}}{\boldsymbol{)}}{\boldsymbol{+}}{\bf{1.2}}{\boldsymbol{\ast }}(\frac{{\boldsymbol{V}}{\boldsymbol{C}}{\boldsymbol{N}}}{{\boldsymbol{F}}{\boldsymbol{N}}})$$\end{document}deduced:CAPscore=0.7+1.9∗(ABR)+1.2∗(VCNFN). We found that preoperative ABR and area ratio of VCN to FN at the cerebellopontine angle could predict CI outcome in patients with CND. Preoperative counselling based on our predictive model might be helpful to determine treatment modality for auditory rehabilitation and which ear to implant.

Children with unilateral cochlear nerve canal stenosis have bilateral cochleovestibular anomalies

OBJECTIVES/HYPOTHESIS

To investigate the cochleovestibular apparatus bilaterally in children with isolated unilateral bony cochlear nerve canal (bCNC) stenosis.

STUDY DESIGN

Retrospective review.

METHODS

Imaging studies of children with unilateral bCNC stenosis (<1.0 mm) on computed tomography imaging (N = 36) were compared with controls imaged due to trauma without temporal bone injury (N = 32). Twenty-six measurements were obtained in each ear, assessing the bony internal auditory canal (IAC), cochlea, and vestibular end-organs, and were analyzed using one-way analysis of variance for intersubject comparisons and paired t tests for intrasubject comparisons with a Bonferroni adjustment for multiple comparisons (P = .0006).

RESULTS

Patients with bCNC stenosis had a smaller IAC (P < .000) and cochlea (P < .000) on the stenotic side as compared with controls. Although the vestibular end-organ was also smaller in bCNC ears, this difference was not significant. The contralateral ear also had a smaller bCNC (P < .000) and cochlea (P < .000) as compared with controls, although to a lesser degree than the stenotic side.

CONCLUSIONS

Children with unilateral bCNC stenosis have abnormal biometry of both the cochlea and the vestibular end-organ in the affected and the normal contralateral ear as compared with controls.

LEVEL OF EVIDENCE

3b Laryngoscope, 129:2403-2408, 2019.

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.

Assessing the Benefit-Risk Profile for Pediatric Implantable Auditory Prostheses

BACKGROUND/AIMS

Children with congenital cochleovestibular abnormalities associated with profound hearing loss have few treatment options if cochlear implantation does not yield benefit. An alternative is the auditory brainstem implant (ABI). Regulatory authority device approvals currently include a structured benefit-risk assessment. Such an assessment, for regulatory purposes or to guide clinical decision making, has not been published, to our knowledge, for the ABI and may lead to the design of a research program that incorporates regulatory authority, family, and professional input.

METHODS

Much structured benefit-risk research has been conducted in the context of drug trials; here we apply this approach to device studies. A qualitative framework organized benefit (speech recognition, parent self-report measures) and risk (surgery- and device-related) information to guide the selection of candidates thought to have potential benefit from ABI.

RESULTS

Children with cochleovestibular anatomical abnormalities are challenging for appropriate assessment of candidacy for a cochlear implant or an ABI. While the research is still preliminary, children with an ABI appear to slowly obtain benefit over time. A team of professionals, including audiological, occupational, and educational therapy, affords maximum opportunity for benefit.

CONCLUSIONS

Pediatric patients who have abnormal anatomy and are candidates for an implantable auditory prosthetic require an individualized, multisystems review. The qualitative benefit-risk assessment used here to characterize the condition, the medical need, potential benefits, risks, and risk management strategies has revealed the complex factors involved. After implantation, continued team support for the family during extensive postimplant therapy is needed to develop maximum auditory skill benefit.

Bony cochlear nerve canal stenosis in pediatric unilateral sensorineural hearing loss

OBJECTIVES

This study was performed to evaluate the frequency of bony cochlear nerve canal (BCNC) stenosis and its clinical significance in pediatric patients with unilateral sensorineural hearing loss (SNHL) of unknown etiology.

MATERIALS AND METHODS

We analyzed the medical records and temporal bone computed tomography (CT) results of patients less than 13 years of age with a diagnosis of unilateral SNHL of unknown etiology between July 2007 and July 2017. We compared the BCNC diameter between both sides and analyzed the age at diagnosis, degree of hearing loss, and accompanying inner ear anomalies.

RESULTS

In 42 patients, the mean age at diagnosis was 7.4 ± 3.6 years, and the average hearing level in the affected ear was 87.9 ± 20.0 dB HL (decibels hearing level). The average diameter of the BCNC was 1.22 ± 0.75 mm on the affected side and 1.96 ± 0.52 mm on the normal side. The most suitable criterion for BCNC stenosis appeared to be a diameter of 1.2 mm by the recursive partitioning procedure. With application of this criterion, the rate of BCNC stenosis was significantly greater on the affected side than on the normal side (52.4% vs. 4.8%, respectively; P < 0.05). A narrow internal acoustic canal was found in two patients, and vestibular and cochlear anomalies were found in three patients each.

CONCLUSIONS

Our results suggest that it is reasonable to set a diameter of 1.2 mm as a cutoff for BCNC stenosis, and also that BCNC stenosis is a common cause of unilateral SNHL of unknown etiology in childhood.

Progression of Unilateral Hearing Loss in Children With and Without Ipsilateral Cochlear Nerve Canal Stenosis: A Hazard Analysis

OBJECTIVE

To investigate the risk of hearing loss progression in each ear among children with unilateral hearing loss associated with ipsilateral bony cochlear nerve canal (BCNC) stenosis.

SETTING

Tertiary pediatric referral center.

PATIENTS

Children diagnosed with unilateral hearing loss who had undergone temporal bone computed tomography imaging and had at least 6 months of follow-up audiometric testing were identified from a prospective audiological database.

INTERVENTIONS

Two pediatric radiologists blinded to affected ear evaluated imaging for temporal bone anomalies and measured bony cochlear canal width independently. All available audiograms were reviewed, and air conduction thresholds were documented.

MAIN OUTCOME MEASURE

Progression of hearing loss was defined by a 10 dB increase in air conduction pure-tone average.

RESULTS

One hundred twenty eight children met inclusion criteria. Of these, 54 (42%) had a temporal bone anomaly, and 22 (17%) had ipsilateral BCNC stenosis. At 12 months, rates of progression in the ipsilateral ear were as follows: 12% among those without a temporal bone anomaly, 13% among those with a temporal bone anomaly, and 17% among those with BCNC stenosis. Children with BCNC stenosis had a significantly greater risk of progression in their ipsilateral ear compared with children with no stenosis: hazard ratio (HR) 2.17, 95% confidence interval (CI) (1.01, 4.66), p value 0.046. When we compared children with BCNC stenosis to those with normal temporal bone imaging, we found that the children with stenosis had nearly two times greater risk estimate for progression, but this difference did not reach significance, HR 1.9, CI (0.8, 4.3), p = 0.1. No children with BCNC stenosis developed hearing loss in their contralateral year by 12 months of follow-up.

CONCLUSION

Children with bony cochlear nerve canal stenosis may be at increased risk for progression in their ipsilateral ear. Audiometric and medical follow-up for these children should be considered.

Characteristics of electrically evoked auditory brainstem responses in patients with cochlear nerve canal stenosis receiving cochlear implants

OBJECTIVE

To explore the characteristics of the electrically evoked auditory brainstem responses (EABR) in children with cochlear nerve canal stenosis (CNCs) following cochlear implantation (CI), and the EABR thresholds in children with stenotic versus normal cochlear nerve canals.

METHOD

Sixteen children with profound sensorineural hearing loss were included in this study: 8 with CNCs (CNCs group) and 8 with normal cochlear nerve canals (control group). All children underwent cochlear implantation with full insertion of all electrodes. EABR was performed 6 months postoperatively in both groups.

RESULTS

The EABR extraction rate was 100% in children with normal cochlear nerve canals and only 50% in children with CNCs. EABR thresholds were significantly higher in children with CNCs of electrodes No. 11and 22 than in children with normal cochlear nerve canals (P < 0.05 for both comparisons). There was no significant difference in EABR thresholds among electrode No. 1, 11 and 22 in CNCs group (P > 0.05 for all comparisons); while in the control group, the EABR threshold at electrode No 22 was lower than those at both electrodes No. 11 and 1 (P < 0.05 for both comparisons), and the EABR threshold at electrode No. 11 was also lower than that at electrode No. 1 (P < 0.05).

CONCLUSION

The EABR thresholds in children with normal cochlear nerve canals vary according to the different locations of electrodes in the cochlea; while in children with CNCs, there was no significant difference among different electrode locations. The EABR thresholds in CNCs children were higher than those of children with normal cochlear nerve canals at electrode 11 and 22.

Radiological Evaluation of Inner Ear with Computed Tomography in Patients with Unilateral Non-Pulsatile Tinnitus

OBJECTIVE

The objective of this research was to investigate the possible relationship between tinnitus and certain bony inner ear structures using computed tomography (CT).

MATERIALS AND METHODS

This was a prospective, controlled, double-blind study. The subjects of the study were divided into the following three groups: group 1 (G1), patients with unilateral sensorineural hearing loss (SNHL) and unilateral non-pulsatile tinnitus in the same ear; group 2 (G2), patients with normal hearing and unilateral non-pulsatile tinnitus; and group 3 (G3), healthy volunteers with neither tinnitus nor hearing loss. The basal turn length, internal acoustic canal (IAC) width and length, bony cochlear nerve canal (BCNC) width, and IAC diameter at the porus acousticus internus (PAI) were measured.

RESULTS

The mean BCNC width was significantly narrower in G1 and G2 than in the control group (G3) (p<0.001). For patients in G2, BCNC width was significantly narrower in ears with tinnitus (p<0.001) than in ears without tinnitus. The mean IAC diameter at PAI was also narrower in the G1 patients (p=0.007) compared with the other groups.

CONCLUSION

The results of this study suggest that CT evaluation of the inner ear structures is important in patients with tinnitus. According to the results, a narrow BCNC may cause phantom sensations and be related to cochlear nerve dysfunction. Therefore, it is recommended that clinicians evaluate BCNC carefully while assessing such patients.

Bony cochlear nerve canal and internal auditory canal measures predict cochlear nerve status

Objectives:

The bony cochlear nerve canal is the space between the fundus of the internal auditory canal and the base of the cochlear modiolus that carries cochlear nerve fibres. This study aimed to determine the distribution of bony labyrinth anomalies and cochlear nerve anomalies in patients with bony cochlear nerve canal and internal auditory canal atresia and stenosis, and then to compare the diameter of the bony cochlear nerve canal and internal auditory canal with cochlear nerve status.

Methods:

The study included 38 sensorineural hearing loss patients (59 ears) in whom the bony cochlear nerve canal diameter at the mid-modiolus was 1.5 mm or less. Atretic and stenotic bony cochlear nerve canals were examined separately, and internal auditory canals with a mid-point diameter of less than 2 mm were considered stenotic. Temporal bone computed tomography and magnetic resonance imaging scans were reviewed to determine cochlear nerve status.

Results:

Cochlear hypoplasia was noted in 44 out of 59 ears (75 per cent) with a bony cochlear nerve canal diameter at the mid-modiolus of 1.5 mm or less. Approximately 33 per cent of ears with bony cochlear nerve canal stenosis also had a stenotic internal auditory canal and 84 per cent had a hypoplastic or aplastic cochlear nerve. All patients with bony cochlear nerve canal atresia had cochlear nerve deficiency. The cochlear nerve was hypoplastic or aplastic when the diameter of the bony cochlear nerve canal was less than 1.5 mm and the diameter of the internal auditory canal was less than 2 mm.

Conclusion:

The cochlear nerve may be aplastic or hypoplastic even if temporal bone computed tomography findings indicate a normal cochlea. If possible, patients scheduled to receive a cochlear implant should undergo both computed tomography and magnetic resonance imaging of the temporal bone. The bony cochlear nerve canal and internal auditory canal are complementary structures, and both should be assessed to determine cochlear nerve status.

Management of unilateral hearing loss

OBJECTIVE

A representative sample of literature regarding unilateral hearing loss (UHL) was reviewed to provide evidence of the effects of UHL and the intervention options available for children with UHL. Considerations during the assessment and management of children with UHL are illustrated using case illustrations.

METHOD

Research articles published from 2013 to 2015 were searched in the PubMed database using the keywords "unilateral hearing loss". Articles from 1950 to 2013 were included from a previous literature review on minimal hearing loss [1]. A retrospective review of charts of 14 children with UHL was also conducted.

RESULTS

The evidence indicates that children with UHL are more likely to have structural anomalies of the inner ear; may face challenges in six different domains, and have six intervention options available. Evidence also indicates that although some children appear to exhibit no delays or difficulties, others have significant challenges, some of which continue into adulthood.

CONCLUSIONS

Children with UHL have to be treated on a case-by-case basis. Parent education regarding UHL, its effects, and all available management options is critical so they can make informed decisions. Close monitoring and good communication between professionals in different domains is crucial in order to minimize the potential negative effects of UHL.

Cochlear Implantation in Patients With CHARGE Syndrome

OBJECTIVE

To determine the optimal surgical approach for cochlear implantation (CI) preoperatively based on the spatial relation of a displaced facial nerve (FN) and middle ear structures and to analyze clinical outcomes of CHARGE syndrome.

METHODS

Facial nerve displacement and associated deviation of inner ear structures were analyzed in 13 patients (17 ears) with CHARGE syndrome who underwent CI. Surgical accessibility through the facial recess was assessed based on anatomical landmarks. Postoperative speech performance and associated clinical characteristics were analyzed.

RESULTS

The most consistently identified ear anomalies were semicircular canal aplasia (100%), ossicular anomaly (100%), and vestibular hypoplasia (88%). Facial nerve displacement was found in 77% of cases (anteroinferior: 47%, anterior: 24%, inferior: 6%). The width of available surgical space around facial recess was significantly greater in cases of facial recess approach (2.85 ± 0.9 mm) than those of alternative approach (0.12 ± 0.29 mm, P = .02). Postoperatively, 53% achieved better than category 4 on the categories of auditory perception (CAP) scale. The CAP category was significantly correlated with internal auditory canal diameter (P = .025) and did not differ according to the applied surgical approach.

CONCLUSION

Preoperative determination of surgical accessibility through facial recess would be useful for safe surgical approach, and successful hearing rehabilitation was achievable by applying appropriate surgical approaches.

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.

Bony cochlear nerve canal stenosis and speech discrimination in pediatric unilateral hearing loss

OBJECTIVES/HYPOTHESIS

To examine the relationship between bony cochlear nerve canal (BCNC) width, degree of hearing loss, and speech discrimination in children with unilateral sensorineural hearing loss (USNHL).

STUDY DESIGN

Retrospective chart review (case-control study).

METHODS

Audiometric database was cross-referenced with radiologic database at pediatric tertiary care facility to identify children with USNHL and temporal bone computed tomography. BCNC widths were measured independently by two radiologists blinded to affected ear. Regression analyses investigated associations among variables.

RESULTS

One hundred and sixty children with USNHL had temporal bone imaging. Mean BCNC width was significantly smaller in affected ears, P = 0.0001. Narrower width was associated with more severe hearing loss, P = 0.01. Among children who had narrower cochlear nerve canals in affected ears compared to unaffected ears, smaller width was associated with lower speech discrimination score, P = 0.03. Increasing asymmetry in BCNC width between affected and unaffected ears was associated with poorer discrimination scores, P = 0.02. Among ears with asymmetrically smaller cochlear nerve canals, a 1-mm reduction in cochlear canal width between the normal and affected ear was associated with 30.4% lower word recognition score percentage in the affected ear, P = < 0.001.

CONCLUSION

There is a significant association between BCNC stenosis and impaired speech discrimination, independent of degree of hearing loss. Further investigation is needed to determine whether BCNC stenosis is a poor prognostic factor for auditory rehabilitation.

High-resolution CT findings in children with a normal pinna or grade I microtia and unilateral mild stenosis of the external auditory canal

SUMMARY

A subset of patients presents with unilateral conductive hearing loss, a normal pinna or grade I microtia, and mild external auditory canal stenosis. The physical findings of microtia and a small external canal are commonly absent or subtle in this group of patients, who are being commonly referred for imaging to evaluate isolated conductive hearing loss. We present a case series of patients with unilateral conductive hearing loss and characteristic ossicular abnormalities, commonly anterior fixation of the malleus. All patients had a significantly increased distance from the cochlear promontory to the handle of the malleus and an abnormal incudostapedial angle, indicative of an abnormal ossicular position and/or morphology. Successful surgical reconstruction of the ossicular chain was attempted and accomplished in 3 patients.