Significance of unilateral enlarged vestibular aqueduct

A Case Report of Malignant Cerebellopontine Angle Lesion Highlighting the Interdisciplinary Diagnostic Challenge in the Case of Unilateral Progressive Hearing Loss

The authors present the case of a young boy who experienced progressive unilateral hearing loss initially believed to be unrelated to any other medical condition. Methods: The patient received a thorough evaluation, which included a comprehensive battery of audiological tests, a CT scan, and a gadolinium-enhanced MRI. Results: A repeated imaging investigation revealed the presence of a mass that mimicked a vestibular schwannoma (VS), but despite this, the boy was ultimately diagnosed with cerebral manifestations of B-cell acute lymphoblastic leukemia (B-ALL). Conclusions: Cerebral lesions originating from the internal auditory canal are rare in cases of B-ALL. In this case, the initial signs and symptoms of the disease were solely related to the audiovestibular system, making the diagnostic process particularly complicated. Unilateral hearing loss cases may indicate the presence of potentially life-threatening conditions, even if the hearing loss appears to be clinically non-syndromic. For these reasons, unilateral hearing losses necessitate a comprehensive interdisciplinary diagnostic approach from the very start of auditory manifestation and, in particular, if the hearing impairment demonstrates threshold progression.

Newborn Hearing Screening Results in Patients with Enlarged Vestibular Aqueduct

OBJECTIVES

Enlarged vestibular aqueduct (EVA) is the most common anatomic abnormality contributing to permanent hearing loss (HL) in children. Although the association between EVA and HL is well-documented, the pass rate for the newborn hearing screening (NBHS) for patients with EVA-related HL is not. Our objective was to investigate the association between NBHS results and audiologic and clinical outcomes in a large cohort of pediatric patients with EVA.

METHODS

This was a retrospective chart review of patients seen in the Boston Children's Hospital (BCH) Department of Otolaryngology and Communication Enhancement with confirmed HL, known NBHS results, and confirmed EVA. Demographic, clinical, audiologic, and imaging data were collected from the medical record. Frequency-specific data points from pure-tone audiograms and/or automated auditory brainstem response tests were recorded, and four-frequency pure tone average was calculated using air conduction thresholds at 500, 1000, 2000, and 4000 Hz.

RESULTS

Of the 183 patients included in the study, 84 (45.9%) passed their NBHS, whereas 99 (54.1%) did not pass. Compared with patients who did not pass, patients who passed were more likely to have unilateral EVA and unilateral HL, whereas they were less likely to undergo cochlear implantation and to have causative SLC26A4 variants.

CONCLUSIONS

EVA-associated HL may be identified at birth or during childhood, with nearly half the patients in this cohort passing their NBHS. Our results provide prognostic information for patients with EVA who pass their NBHS and highlight the importance of regular hearing monitoring for children not initially suspected of having HL.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2786-2791, 2023.

A Prospective Study of Genetic Variants in Infants with Congenital Unilateral Sensorineural Hearing Loss

Children with unilateral sensorineural hearing loss (uSNHL) have a high risk of speech-language delays and academic difficulties. Still, challenges remain in the diagnosis of uSNHL. With a prospective cross-sectional design, 20 infants were consecutively recruited from a universal newborn hearing screening program and invited to genetic testing. Eighteen of the subjects agreed to genetic testing, 15 subjects with OtoSCOPE^® v.9 screening 224 genes, and four subjects underwent targeted testing, screening for chromosomal abnormalities or 105-137 gene mutations. The genetic results were described together with the 20 infants' previously published auditory profiles and imaging results. Genetic causes for the uSNHL were found in 28% of subjects (5/18) including CHARGE syndrome (CHD7), autosomal recessive non-syndromic hearing loss (GJB2), Townes-Brocks syndrome (SALL1), Pendred Syndrome (SLC26A4) and Chromosome 8P inverted duplication and deletion syndrome. In subjects with comorbidities (malformation of fingers, anus, brain, and heart), 100% were diagnosed with a genetic cause for uSNHL (3/3 subjects), while 13% (2/15 subjects) were diagnosed without comorbidities observed at birth (p = 0.002). Genetic testing for congenital uSNHL is currently efficient for alleged syndromes, whereas genetic variants for non-syndromic congenital uSNHL need further research.

Investigating the significance of vestibular aqueduct pneumatization and pediatric hearing loss

INTRODUCTION

Vestibular aqueduct enlargement on imaging is associated with pediatric hearing loss, though the mechanism is not well understood. After reviewing temporal bone imaging in pediatric patients from our institution with no obvious cause of hearing loss, we postulate that pneumatization of bone surrounding the vestibular aqueduct may also be associated with hearing loss.

METHODS

342 temporal bone CT scans performed at Children's Hospital of Michigan between January 2018 and December 2020 were reviewed. Scans were assessed for the presence, laterality, and degree of vestibular aqueduct pneumatization (PVA). Electronic medical record data was collected on age, gender, hearing status, medical comorbidities, and otologic comorbidities. Cases were secondarily reviewed to ensure validity. 159 patients were included in the final analysis; excluded scans included duplicates, patients with unknown hearing status, patients older than 21 years old, and patients with another known cause of hearing loss including inner ear malformations.

RESULTS

17.6% of patients demonstrated vestibular aqueduct pneumatization. Hearing loss percentage was comparable between the PVA and non-pneumatized group (42.9% vs 42.0%), but hearing loss was more likely to be sensorineural in the PVA group (91.7% vs 80.0%). When patients with only newborn hearing data available were excluded from the PVA group, hearing loss percentage was higher in the PVA group (50% vs 42.0%). Patients with hearing loss in the PVA group were older than those without hearing loss (14.92 years old vs 10.67 years old).

CONCLUSION

Hearing loss in enlarged vestibular aqueduct syndrome is typically progressive, bilateral, and sensorineural. Our preliminary findings suggest that vestibular aqueduct pneumatization may be another anomaly associated with a primarily sensorineural hearing loss. Further studies are needed to strengthen this postulated link.

Enlarged Vestibular Aqueduct: Disease Characterization and Exploration of Potential Prognostic Factors for Cochlear Implantation

OBJECTIVES

There is an unmet need to match the anticipated natural history of hearing loss (HL) in enlarged vestibular aqueduct (EVA) with clinical management strategies. The objectives of this study are therefore to provide a detailed case characterization of an EVA cohort and explore the relationship between candidate prognostic factors and timing of cochlear implant (CI) surgery.

STUDY DESIGN

A multicenter retrospective review of patients diagnosed with EVA.

SETTING

Patient data recruitment across three CI centers in the UK.

PATIENTS

One hundred fifty patients with a radiological diagnosis of EVA from January 1995 to January 2021.

MAIN OUTCOME MEASURES

Age at audiological candidacy for CI and age at first implant surgery.

RESULTS

EVA was predominately a bilateral condition (144/ 150) with increased prevalence in women (M:F, 64:86). 51.7% of patients failed new-born hearing screening, with 65.7% having HL diagnosed by 1 year. Initial moderate to severe and severe to profound HL were reported most frequently. In 123 patients, median age that audiological candidacy for CI was met for at least one ear was 2.75 years. Median age at first CI was 5 years (140/150).Pendred syndrome (confirmed in 73 patients) and ethnicity, were not significantly associated with earlier CI surgery. Multivariate linear regression demonstrated that male patients have first CI surgery significantly earlier than females (coefficient -0.43, 95% CI [-0.82, -0.05), p-value = 0.028).

CONCLUSIONS

This large UK EVA cohort provides evidence that patients should be closely monitored for CI candidacy within the first 3 years of life. Significantly, male gender is emerging as an independent prognostic factor for earlier assessment and first CI surgery.

Predictive Modeling and Risk Stratification of Patients With Enlarged Vestibular Aqueduct

OBJECTIVES/HYPOTHESIS

To investigate patient-specific characteristics that independently predict for progressive hearing loss in patients with enlarged vestibular aqueduct (EVA). Utilize multivariable predictive models to identify subgroups of patients with significantly different progression risks.

STUDY DESIGN

Retrospective analysis of patients evaluated at an academic tertiary care center. Cohort included 74 ears of patients with a diagnosis of EVA as defined by the Cincinnati criteria.

METHODS

Hearing trajectories were characterized, and a Kaplan-Meier estimator was utilized to determine progressive phenotype probabilities across the first 10 years after diagnosis. Cox proportional hazard regression was used to identify patient characteristics that independently altered this probability. Stratified risk groups were delineated from generated nomogram scores.

RESULTS

Male gender was associated with a 4.53 hazard ratio for progressive hearing loss (95% confidence interval [CI], 2.53 to 12.59). Each millimeter increase in operculum size was independently associated with an 80.40% increase in expected hazard (95% CI, 40.18 to 120.62). Each dB increase in air pure tone average at time of diagnosis decreased expected hazard by 1.59% (95% CI, -3.02 to -0.17). The presence of incomplete partition type II was associated with a 2.44 hazard ratio (95% CI, 1.04 to 5.72). Risk groups stratified by median nomogram score evidenced the discriminative ability of our model with the progression probability in the high-risk group being six times higher at 1 year, nearly five times greater at 3 years, and three times greater at 9 years.

CONCLUSIONS

EVA patient characteristics can be used to predict hearing loss probability with a high degree of accuracy (C-index of 0.79). This can help clinicians make more proactive management decisions by identifying patients at high risk for hearing loss.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Contralateral hearing loss in children with a unilateral enlarged vestibular aqueduct

OBJECTIVE

To evaluate the long-term ipsi- and contralateral hearing of patients with a unilateral enlarged vestibular aqueduct (EVA).

STUDY DESIGN

Multicenter retrospective cohort study.

SETTING

Three tertiary otology and audiology referral centers.

PATIENTS AND DIAGNOSTIC INTERVENTIONS

A total of 34 children with a unilateral enlarged vestibular aqueduct as identified on CT and/or MR imaging were evaluated with pure tone and speech perception audiometry.

MEAN OUTCOME MEASURES

Radiologic measurements of the vestibular aqueduct, ipsi- and contralateral hearing loss, ipsi- and contralateral hearing loss progression over time and DNA test results.

RESULTS

All patients in this cohort with unilateral EVA presented with hearing loss. Hearing loss was progressive in 38% of the ipsilateral ears. In 29% of the children, hearing loss was also found in the contralateral ear without EVA. In 90%, the contralateral hearing was stable, with a mean follow up of 4.2 years. We found a significant correlation between the severity of the hearing loss and the size of the EVA. A genetic diagnosis associated with EVA and/or SNHL was found in only 7%.

CONCLUSION

About a third of the children with unilateral EVA are at risk of developing hearing loss in the contralateral ear. This indicates that at least in some patients with a unilateral EVA, a bilateral pathogenic process underlies the hearing loss, in contrary to what the imaging results suggest. These findings are important for counseling of EVA patients and their parents and have implications for follow up.

Genetic Determinants of Non-Syndromic Enlarged Vestibular Aqueduct: A Review

Hearing loss is the most common sensorial deficit in humans and one of the most common birth defects. In developed countries, at least 60% of cases of hearing loss are of genetic origin and may arise from pathogenic sequence alterations in one of more than 300 genes known to be involved in the hearing function. Hearing loss of genetic origin is frequently associated with inner ear malformations; of these, the most commonly detected is the enlarged vestibular aqueduct (EVA). EVA may be associated to other cochleovestibular malformations, such as cochlear incomplete partitions, and can be found in syndromic as well as non-syndromic forms of hearing loss. Genes that have been linked to non-syndromic EVA are SLC26A4, GJB2, FOXI1, KCNJ10, and POU3F4. SLC26A4 and FOXI1 are also involved in determining syndromic forms of hearing loss with EVA, which are Pendred syndrome and distal renal tubular acidosis with deafness, respectively. In Caucasian cohorts, approximately 50% of cases of non-syndromic EVA are linked to SLC26A4 and a large fraction of patients remain undiagnosed, thus providing a strong imperative to further explore the etiology of this condition.

Auditory and imaging markers of atypical enlarged vestibular aqueduct

PURPOSE

To characterize the auditory and imaging markers of atypical enlarged vestibular aqueduct (EVA).

METHODS

15 EVA cases (26 ears) confirmed via high-resolution MRI (HRMRI) that did not meet the Valvassori criterion on high-resolution CT (HRCT) were classified as atypical EVA. Another 21 EVA cases (40 ears) meeting the Valvassori criterion were randomly chosen as typical EVA. The hearing loss (HL), HRCT, and HRMRI findings were compared between the two groups.

RESULTS

The difference of HL severity between atypical and typical EVA was not statistically significant (χ² = 0.12, P > 0.05. The vestibular aqueducts (VA) of atypical EVA cases manifested as borderline dilation (n = 17), focal dilation (n = 3), and normal appearance (n = 6) on the HRCT. The midpoint width of atypical and typical EVA cases was 1.06 ± 0.18 mm and 2.10 ± 0.55 mm, respectively, exhibiting a significant difference (t = - 9.20, P < 0.05). In the HRMRI, the degree of dilation and shape of the intraosseous partition of endolymphatic duct and sac (ES) was similar to that of VA on HRCT, while their extraosseous ES was depicted variable slighter dilation compared to that of typical one, the difference between them was statistically significant (t = - 4.10, P < 0.05).

CONCLUSION

The HL severity of atypical EVA ears was similar to that of typical ones. Nevertheless, borderline, focal dilation and normal-like appearance of VAs on HRCT and variablely slighter dilation of the extraosseous ES on HRMRI are its characteristic imaging findings.

Hearing Loss in Enlarged Vestibular Aqueduct: A Prognostic Factor Systematic Review of the Literature

OBJECTIVE

There is a need to highlight individual prognostic factors determining hearing loss in enlarged (wide) vestibular aqueduct, as currently clinicians cannot counsel parents about the expected clinical course, nor provide individualized hearing rehabilitation plans following identification at newborn screening. We apply a novel methodology to specifically outline and assess the accuracy of prognostic factors reporting for hearing loss in enlarged vestibular aqueduct.

DATA SOURCES

A preferred reporting items for systematic reviews and meta-analyses compliant systematic review (Prospero ID: CRD42019151199), with searches applied to Medline, EMBASE, and Cochrane. Studies with longitudinal design were included between 1995 and 2019.

STUDY SELECTION

The CHARMS-PF tool was used to assess robustness of prognostic factor study designs.

DATA EXTRACTION

The QUIPS tool was used to assess for individual study risk of bias.

DATA SYNTHESIS & RESULTS

Seventy papers were suitable for data extraction. In the six studies with low risk of bias, the domains of enlarged vestibular aqueduct (EVA) morphology, age, hearing thresholds, sex, head trauma, and genotype provided exploratory prognostic factors for hearing loss associated with enlarged vestibular aqueduct. Overall, study heterogeneity and risk of bias precluded reporting by forest plots and meta-analysis.

CONCLUSIONS

The majority of exploratory prognostic factor studies for hearing loss associated with enlarged vestibular aqueduct are hampered by risk of bias. However, this systematic review identifies potential independent prognostic factors which should be measured, and adjusted for, in subsequent confirmatory studies utilizing multivariate analysis. This would determine the true independent prognostic effects associated with hearing loss in enlarged vestibular aqueduct, while facilitating prognostic model development and the ability to predict individual hearing loss trajectory.

Development of in-house genetic screening for pediatric hearing loss

OBJECTIVES

To evaluate the efficiency of in-house genetic testing for mutations causing the most common types of inherited, nonsyndromic, sensorineural hearing loss (SNHL).

METHODS

Retrospective cohort study of 200 patients at a single, pediatric medical center with suspected or confirmed hearing loss who underwent either send out vs in-house genetic testing for mutations in GJB2/GJB6, SLC26A4, and MTRNR1. Primary outcome measure was the difference in mean turnaround time for send-out vs in-house genetic testing. Additional outcomes included associations between audiometric findings and genetic test results.

RESULTS

One hundred four send-out tests were performed between October 2010 and June 2014, and 100 in-house tests were performed between November 2014 and November 2016. The mean turnaround time for send-out testing was 53.7 days. The mean turnaround time for in-house testing was 18.9 days. This difference was statistically significant (P < .001). The largest component of turnaround time was the amount of time elapsed between receipt of specimen in the lab and final test result. These intervals were 47.0 and 18.3 days for send-out and in-house tests, respectively. Notably, the longest turnaround time for in-house testing (43 days) was less than the average turnaround time for send-out testing. In addition, we identified two simple audiometric parameters (ie, bilateral newborn hearing screen referral and audiometry showing symmetric SNHL) that may increase diagnostic yield of genetic testing.

CONCLUSIONS

The development of in-house genetic testing programs for inherited SNHL can significantly reduce testing turnaround times. Newborn hearing screening and audiometry results can help clinicians identify patients most likely to benefit from genetic testing.

LEVEL OF EVIDENCE

IV.

Cochlear Implantation in Children with Single-Sided Deafness

OBJECTIVE

To describe our experience with children undergoing unilateral cochlear implantation (CI) for treatment of single-sided deafness (SSD).

STUDY DESIGN

Retrospective case series.

METHODS

A retrospective case review from a tertiary referral center involving 14 pediatric patients (<18 years) with SSD who underwent unilateral CI. Speech perception testing in quiet and noise in the CI-only and bimodal conditions with at least 1 year of device use and device usage from data logs represent the main outcome measures.

RESULTS

The mean age at CI was 5.0 years (median 4.4, range 1.0-11.8 years). The mean duration of deafness was 3.0 years (median 2.4, range 0.6-7.0 years). Mean follow-up was 3.4 years. Speech perception testing with a minimum of 1 year post-CI was available in eight patients. The mean word recognition scores (WRS) in the CI-only condition was 56%; a significant improvement from baseline. Testing in background noise with spatially separated speech and noise revealed that patients scored as well or better with the CI-on versus CI-off in all conditions and in no cases was interference from the CI noted. Data logs were reviewed for device usage which revealed an average use of 6.5 hr/d.

CONCLUSION

Cochlear implantation is a viable treatment option for pediatric SSD in this self-selected cohort. Open-set speech and improvement in background noise can be achieved. Careful patient selection and thorough counseling on expectations is paramount to achieving successful outcomes.

LEVEL OF EVIDENCE

IV Laryngoscope, 131:E271-E277, 2021.

Association of SLC26A4 mutations, morphology, and hearing in pendred syndrome and NSEVA

OBJECTIVE

To investigate the relations of monoallelic (M1), biallelic (M2), or the absence of mutations (M0) in SLC26A4 to inner ear morphology and hearing levels in individuals with Pendred syndrome (PS) or nonsyndromic enlarged vestibular aqueduct (NSEVA) associated with hearing loss.

METHODS

In a cohort of 139 PS/NSEVA individuals, 115 persons from 95 unrelated families had full genetic sequencing of SLC26A4, and 113 had retrievable images for re-assessment of inner ear morphology. The association between the number of mutant alleles in SLC26A4, inner ear morphology (including endolymphatic sac size and protein content on magnetic resonance imaging), and hearing level (pure tone average) was explored.

RESULTS

Biallelic SLC26A4 mutations (M2) occurred in three-quarters of the cohort and was invariably associated with poor hearing; in 87%, it was associated with incomplete partition type II of the cochlea as well as enlarged endolymphatic sac and vestibular aqueduct. M1 or M0 individuals exhibited a greater variability in inner ear morphology. Endolymphatic sac size and presence of "high-protein" sac contents were significantly higher in M2 individuals compared to M1 and M0 individuals.

CONCLUSION

The number of SLC26A4 mutations is associated with severity and variability of inner ear morphology and hearing level in individuals with PS or NSEVA. M2 individuals have poorer hearing and present largely incomplete partition type II of the cochleas with enlarged endolymphatic sacs, whereas individuals with M1 and no detectable SLC26A4 mutations have less severe hearing loss and more diverse inner ear morphology.

LEVEL OF EVIDENCE

4. Laryngoscope, 129:2574-2579, 2019.

Imaging findings in pediatric single-sided deafness and asymmetric hearing loss

OBJECTIVE

To examine the imaging findings on computer tomography (CT) and magnetic resonance imaging (MRI) in pediatric single-sided deafness (SSD) and asymmetric hearing loss (ASH).

METHODS

The medical records of 189 pediatric patients with SSD and ASH were retrospectively reviewed, and imaging findings were compared. SSD was defined as unilateral profound hearing loss and contralateral normal hearing ear. In the ASH group, ASHw was defined as the worse hearing ear with profound hearing loss, while ASHb was defined as the better hearing ear with mild-moderate hearing loss.

RESULTS

There were 170 patients with SSD and 19 patients with ASH. In the SSD group, 83 patients (48.8%) had imaging findings associated with hearing loss. In the ASH group, such imaging findings were found in six (31.6%) of the ASHw and in five (26.3%) of the ASHb ears. The most common finding in the SSD group was cochlear nerve deficiency (50.6%), followed by cochlear dysplasia (39.8%) and enlarged vestibular aqueduct (26.5%). In the ASH groups, cochlear dysplasia was seen in three (50%) of ASHw ears and in two (40%) of the ASHb ears, and enlarged vestibular aqueduct was seen in three (50%) of ASHw ears and in two (40%) of the ASHb ears.

CONCLUSION

Imaging studies identified the etiology in half of the cases of SSD and in one-third of ASH patients. Our findings strongly support the use of imaging studies in the evaluation of pediatric SSD and ASH.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1007-1010, 2020.

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.

Audiometric findings in children with unilateral enlarged vestibular aqueduct

OBJECTIVE

To evaluate the prevalence of bilateral hearing loss in children with unilateral enlarged vestibular aqueduct (EVA) at a single institution.

METHODS

A retrospective case review was performed at a tertiary care pediatric referral center involving children with radiologic findings of unilateral EVA and normal labyrinthine anatomy of the contralateral ear diagnosed via CT and/or MRI. The main outcome measure of interest is the number of patients with unilateral EVA who were diagnosed with bilateral hearing loss.

RESULTS

Sixty-one pediatric patients were identified. The mean audiometric follow-up was 48.2 months (0-150). Three (4.9%) patients with unilateral EVA were noted to have bilateral hearing loss, and this rate was not significantly different (p = 1.0) from the rate reported in a comparison group of patients with contralateral hearing loss (6.0%) without an EVA. The pure-tone average (defined as the average dB HL at 500, 1000, 2000, and 4000 Hz) in the group with bilateral hearing loss was 31.3 dB HL in the better hearing ear and 79.6 dB HL in the worse hearing ear, with the difference being statistically significant (p = 0.02). In the unilateral EVA patients without contralateral hearing loss (n = 56, 91.8%), the PTA was 9.4 dB HL in the better hearing ear and 51.9 dB HL in the worse hearing ear, with the difference being statistically significant (p < 0.001). Two patients (3.3%) with unilateral EVA were found to have hearing within normal limits bilaterally. The EVA was ipsilateral to the worse hearing ear in all cases.

CONCLUSION

The prevalence of bilateral hearing loss in children with unilateral EVA appears to be low. Specifically, it may be no different than the rate of contralateral hearing loss in children with unilateral hearing loss without an EVA. The present report is somewhat different than the previously described prevalence in the literature. This difference could be related to the imaging type and diagnostic criteria used, the patients included, the source of the identified patents, and the overall population of patients studied.

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.

Hearing loss in unilateral and bilateral enlarged vestibular aqueduct syndrome

OBJECTIVE

To investigate any meaningful differences in hearing between patients with unilateral and bilateral enlarged vestibular aqueduct (EVA). EVA is a common radiological finding in children presenting with hearing loss. We hope to provide insight into the pathogenesis of EVA and provide further guidelines for unilateral EVA management. We hypothesized that hearing loss in unilateral EVA would be similar to that seen in bilateral EVA.

METHODS

A longitudinal retrospective study design was used. Three measures of hearing, pure tone average (PTA) word recognition score (WRS) and speech awareness threshold (SAT) and radiologic morphologies were tested for difference across unilateral versus bilateral ear EVA status. Linear mixed effects models were used to identify differences while accounting for time and multiple measurements per ear.

RESULTS

Using Cincinnati criteria, 89 ears fit inclusion criteria, 75 of which were from patients with bilateral EVA compared to 14 ears from patients with unilateral EVA. No significant differences across bilateral status were observed in audiological measurements. Models showed that speech recognition threshold (SRT) (p = 0.925), word recognition score (WRS)(p = 0.521) and pure tone average (PTA) of air and bone conduction from 250 to 4000 Hz (p = 0.281-0.933) were not statistically different with respect to bilateral status. Wilcoxon rank-sum tests showed no statistical difference in vestibular aqueduct width or operculum size (VA)(p = 0.234, p = 0.623). Each year after the first audiogram was associated with significantly greater SRT (p = 0.003) decreased WRS (0.014) and increased PTA (0.003.). Greater midpoint width was associated with significantly lower SRT (p = 0.004) WRS (<0.001) and PTA (<0.001.) CONCLUSION: Our results indicate no statistically significant difference in hearing ability with respect to bilateral EVA status, suggesting that unilateral EVA patients require close follow-up. Our results also demonstrate the progressive nature of EVA and a relationship between VA midpoint width and hearing loss severity.

Functional Testing of SLC26A4 Variants-Clinical and Molecular Analysis of a Cohort with Enlarged Vestibular Aqueduct from Austria

The prevalence and spectrum of sequence alterations in the SLC26A4 gene, which codes for the anion exchanger pendrin, are population-specific and account for at least 50% of cases of non-syndromic hearing loss associated with an enlarged vestibular aqueduct. A cohort of nineteen patients from Austria with hearing loss and a radiological alteration of the vestibular aqueduct underwent Sanger sequencing of SLC26A4 and GJB2, coding for connexin 26. The pathogenicity of sequence alterations detected was assessed by determining ion transport and molecular features of the corresponding SLC26A4 protein variants. In this group, four uncharacterized sequence alterations within the SLC26A4 coding region were found. Three of these lead to protein variants with abnormal functional and molecular features, while one should be considered with no pathogenic potential. Pathogenic SLC26A4 sequence alterations were only found in 12% of patients. SLC26A4 sequence alterations commonly found in other Caucasian populations were not detected. This survey represents the first study on the prevalence and spectrum of SLC26A4 sequence alterations in an Austrian cohort and further suggests that genetic testing should always be integrated with functional characterization and determination of the molecular features of protein variants in order to unequivocally identify or exclude a causal link between genotype and phenotype.

Unilateral Enlarged Vestibular Aqueduct Syndrome and Bilateral Endolymphatic Hydrops

Enlarged vestibular aqueduct (EVA) syndrome is a common congenital inner ear malformation characterized by a vestibular aqueduct with a diameter larger than 1.5 mm, mixed or sensorineural hearing loss that ranges from mild to profound, and vestibular disorders that may be present with a range from mild imbalance to episodic objective vertigo. In our study, we present the case of a patient with unilateral enlarged vestibular aqueduct and bilateral endolymphatic hydrops (EH). EH was confirmed through anamnestic history and audiological exams; EVA was diagnosed using high-resolution CT scans and MRI images. Therapy included intratympanic infusion of corticosteroids with a significant hearing improvement, more evident in the ear contralateral to EVA. Although most probably unrelated, EVA and EH may present with similar symptoms and therefore the diagnostic workup should always include the proper steps to perform a correct diagnosis. Association between progression of hearing loss and head trauma in patients with a diagnosis of EVA syndrome is still uncertain; however, these individuals should be advised to avoid activities that increase intracranial pressure to prevent further hearing deterioration. Intratympanic treatment with steroids is a safe and well-tolerated procedure that has demonstrated its efficacy in hearing, tinnitus, and vertigo control in EH.

Pendred syndrome

Pendred syndrome is an autosomal recessive disorder that is classically defined by the combination of sensorineural deafness/hearing impairment, goiter, and an abnormal organification of iodide with or without hypothyroidism. The hallmark of the syndrome is the impaired hearing, which is associated with inner ear malformations such as an enlarged vestibular aqueduct (EVA). The thyroid phenotype is variable and may be modified by the nutritional iodine intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4/PDS gene, which encodes the multifunctional anion exchanger pendrin. Pendrin has affinity for chloride, iodide, and bicarbonate, among other anions. In the inner ear, pendrin functions as a chloride/bicarbonate exchanger that is essential for maintaining the composition and the potential of the endolymph. In the thyroid, pendrin is expressed at the apical membrane of thyroid cells facing the follicular lumen. Functional studies have demonstrated that pendrin can mediate iodide efflux in heterologous cells. This, together with the thyroid phenotype observed in humans (goiter, impaired iodine organification) suggests that pendrin could be involved in iodide efflux into the lumen, one of the steps required for thyroid hormone synthesis. Iodide efflux can, however, also occur in the absence of pendrin suggesting that other exchangers or channels are involved. It has been suggested that Anoctamin 1 (ANO1/TMEM16A), a calcium-activated anion channel, which is also expressed at the apical membrane of thyrocytes, could participate in mediating apical efflux. In the kidney, pendrin is involved in bicarbonate secretion and chloride reabsorption. While there is no renal phenotype under basal conditions, severe metabolic alkalosis has been reported in Pendred syndrome patients exposed to an increased alkali load. This review provides an overview on the clinical spectrum of Pendred syndrome, the functional data on pendrin with a focus on its potential role in the thyroid, as well as the controversy surrounding the relative physiological roles of pendrin and anoctamin.

Improvement in imaging common temporal bone pathologies at 3 T MRI: small structures benefit from a small field of view

AIM

To compare image quality and evaluate its clinical importance in common temporal bone pathologies of a pTX-SPACE (parallel transmit [pTX] three-dimensional turbo spin-echo with variable flip angle [SPACE]) magnetic resonance imaging (MRI) sequence improved for spatial resolution to a standard-SPACE sequence exhibiting the same scan time at 3 T.

MATERIALS AND METHODS

Thirty-four patients were examined using a standard-SPACE and resolution improved pTX-SPACE sequence at 3 T MRI. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image quality were assessed. Diseases investigated were vestibular schwannoma (VS), intralabyrinthine schwannoma (ILS), inner ear malformations, labyrinthitis, temporal bone fractures, and situation after VS resection.

RESULTS

Edge definition, intratumoural pattern, discrimination of VS from the modiolus and edge definition of ILS, separability from the spiral lamina, and detectability within cochlear turns were improved on the pTX-SPACE sequence. Detectability of malformations, post-traumatic changes, and discrimination of the cochlear and facial nerve after VS resection was improved on the pTX-SPACE sequence. In labyrinthitis, pTX-SPACE was not superior to standard-SPACE. The SNR and CNR were significantly reduced for pTX-SPACE.

CONCLUSIONS

pTX-SPACE significantly improves the detectability of temporal bone diseases, in particular, VS, ILS, and post-VS resection.

Vestibular pathology in children with enlarged vestibular aqueduct

OBJECTIVES/HYPOTHESIS

To establish the prevalence of abnormal vestibular test findings in children with enlarged vestibular aqueduct (EVA) and determine if these findings correlate with clinical symptoms, radiographic findings (EVA size and laterality), audiometric findings, and genetic testing in these patients.

STUDY DESIGN

Prospective cohort.

METHODS

Patients 3 to 12 years of age with hearing loss and imaging findings consistent with EVA treated at our tertiary care institution were sequentially enrolled from 2009 to 2011. The following six outcome measurements were analyzed: audiometric findings, EVA laterality, temporal bone measurements, genetic testing, vestibular testing (cervical-evoked myogenic potentials, posturography, rotational chair, and calorics), and vestibular symptoms.

RESULTS

Twenty-seven patients with EVA (mean age 9.2 years, 48% female) were enrolled in and completed the study. Vertigo was reported in six patients. Twenty-four of 27 (89%) had at least one abnormal vestibular test result. Midpoint and operculum size correlated with directional preponderance (P = .042 and P = .032, respectively). Also, high-frequency pure tone average (HFPTA) correlated with unilateral weakness (P = .002). Walking at a later age correlated with abnormal posturography results. There was no correlation between EVA laterality and vestibular test findings.

CONCLUSION

We found a high rate of vestibular pathology in children with EVA; however, the prevalence of abnormal vestibular test findings in this patient population was not correlated with vestibular symptoms. Enlarged vestibular aqueduct size, HFPTA, and walking at a later age were correlated with abnormal vestibular test findings. In view of these results, it may be prudent to consider vestibular testing in children with these clinical characteristics.

LEVEL OF EVIDENCE

2b. Laryngoscope, 126:2344-2350, 2016.

Imaging Review of the Temporal Bone: Part II. Traumatic, Postoperative, and Noninflammatory Nonneoplastic Conditions

The first part of this review of the temporal bone discussed anatomy of the temporal bone as well as inflammatory and neoplastic processes in the temporal bone region (1). This second part will first discuss trauma to the temporal bone and posttraumatic complications. The indications for common surgical procedures performed in the temporal bone and their postoperative imaging appearance are then presented. Finally, a few noninflammatory nonneoplastic entities involving the temporal bone are reviewed. They are relatively uncommon diagnoses compared with infectious or inflammatory diseases. However, because patients present with symptoms that are either common (hearing loss) or distinctive (sensorineural hearing loss in a child), they are important for the radiologist to be aware of and recognize.

Progressive Hearing Loss and Head Trauma in Enlarged Vestibular Aqueduct

Objective

Enlarged vestibular aqueduct is the most common radiographically identified cause of congenital sensorineural hearing loss and is frequently progressive. Imaging is often ordered during the workup of children with congenital sensorineural hearing loss in part to identify enlarged vestibular aqueduct given concern for progression with head trauma. However, this association has not been systematically evaluated. We aimed to determine the rate of progression and association with head trauma in individuals with enlarged vestibular aqueduct.

Data Sources

Systematic review of primary studies identified through PubMed, Embase, Cochrane, and Web of Science.

Review Methods

Meta-analysis was performed on patient-level data describing enlarged vestibular aqueduct, progressive sensorineural hearing loss, and head trauma extracted from articles identified on systematic review according to PRISMA guidelines.

Results

Twenty-three studies (1115 ears with enlarged vestibular aqueduct) met inclusion criteria. Progressive sensorineural hearing loss was found in 39.6% of ears, with trauma-associated progression in 12%. Limited case-control data show no difference in the incidence of progression between patients with and without head trauma.

Conclusions

Long-term progressive sensorineural hearing loss is common in enlarged vestibular aqueduct, but its association with head trauma is not strongly supported.

Asymmetric and unilateral hearing loss in children

Asymmetric and unilateral hearing losses in children have traditionally been underappreciated, but health care practitioners are now beginning to understand their effect on development and the underlying pathophysiologic mechanisms. The common wisdom among medical and educational professionals has been that at least one normal-hearing or near-normal-hearing ear was sufficient for typical speech and language development in children. The objective of this review is to illustrate, to the non-otolaryngologist, the consequences of asymmetric and unilateral hearing loss in children on developmental and educational outcomes. Etiology, detection, and management are also discussed. Lastly, implications for further research are considered.

Nystagmus in Enlarged Vestibular Aqueduct: A Case Series

Enlarged vestibular aqueduct (EVA) is one of the commonly identified congenital temporal bone abnormalities associated with sensorineural hearing loss. Hearing loss may be unilateral or bilateral, and typically presents at birth or in early childhood. Vestibular symptoms have been reported in up to 50% of affected individuals, and may be delayed in onset until adulthood. The details of nystagmus in patients with EVA have not been previously reported.

The objectives were to describe the clinical history, vestibular test findings and nystagmus seen in a case series of patients with enlarged vestibular aqueduct anomaly.

Chart review, included computed tomography temporal bones, infrared nystagmography with positional and positioning testing, caloric testing, rotary chair and vibration testing.

Clinical history and nystagmus varied among the five patients in this series. All patients were initially presumed to have benign paroxysmal positional vertigo, but repositioning treatments were not effective, prompting referral, further testing and evaluation. In three patients with longstanding vestibular complaints, positional nystagmus was consistently present. One patient had distinct recurrent severe episodes of positional nystagmus. Nystagmus was unidirectional and horizontal. In one case horizontal nystagmus was consistently reproducible with seated head turn to the affected side, and reached 48 d/s. Nystagmus associated with enlarged vestibular aqueduct is often positional, and can be confused with benign paroxysmal positional vertigo. Unexplained vestibular symptoms in patients with unilateral or bilateral sensorineural hearing loss should prompt diagnostic consideration of EVA.

[Enlarged vestibular aqueduct syndrome: etiology, clinical features, diagnostics, and rehabilitation of the patients]

This publication was designed to describe the clinical manifestations of the enlarged vestibular aqueduct syndrome (EVAS), the currently employed methods for its diagnostics, and the strategy for the rehabilitation of the patients presenting with this pathological condition. In addition, the article provides information about the topographic anatomy and X-ray anatomy of the vestibular aqueduct, the specific clinical features of EVAS, the modern algorithm of its diagnostics, and the facilities for hearing rehabilitation in this group of patients.

Intrafamilial phenotypic variability in families with biallelic SLC26A4 mutations

OBJECTIVES/HYPOTHESIS

Enlarged vestibular aqueduct (EVA) and hearing loss are known to be caused by SLC26A4 mutations, but large phenotypic variability exists among patients with biallelic SLC26A4 mutations. Intrafamilial phenotypic variability was analyzed in multiplex EVA families carrying biallelic SLC26A4 mutations to identify the contribution of SLC26A4 mutations and other genetic or environmental factors influencing the clinical manifestations.

STUDY DESIGN

Retrospective case series.

METHODS

Eleven multiplex Korean families with EVA and hearing loss that carry biallelic mutations of the SLC26A4 gene were included. Genetic analysis for SLC26A4 and other genes including FOXI1, FOXI1-DBD, and KCNJ10 was performed. The auditory and other phenotypes were compared among siblings with the same SLC26A4 mutations.

RESULTS

The difference in the auditory phenotypes was identified between siblings in approximately half of the EVA families. Families with SLC26A4 mutations other than H723R homozygous mutations demonstrated more phenotypic variability, especially in those carrying IVS7-2A>G splice site mutation. Cochlear malformation was a consistent finding among siblings with the same SLC26A4 mutations. No mutation was identified in the FOXI1, FOXI1-DBD, and KCNJ10 genes in the tested families.

CONCLUSIONS

The possibility of variability concerning auditory phenotype should be considered even within family members carrying the same SLC26A4 mutations when providing genetic counseling to multiplex EVA families. Mutations in the currently known genes associated with EVA other than SLC26A4 were not found to be responsible for the intrafamilial phenotypic variability. Modifier genes or environmental factors other than the currently known genes seem to play a role in the phenotypic expressions of EVA patients.