Large vestibular aqueduct syndrome: anatomic and functional parameters

Study of the factors related to air-bone gap in enlarged vestibular aqueduct

BACKGROUND

Over half of patients with enlarged vestibular aqueducts (EVA) will have an air-bonr gap (ABG), however, current research on audiology has focused on the influencing factors of air-conducted.

OBJECTIVE

To retrospectively analyse the influencing factors and clinical manifestations of the bone-conduction threshold and ABG in patients with EVA.

MATERIALS AND METHODS

We included 286 patients with EVA; among them, 126 had full SLC26A4 gene sequence results. We performed a descriptive analysis of the bone-conduction threshold and explored the effect of age. Finally, we analyzed the relationship of ABG and SLC26A4 genes with the degree of vestibular aqueduct (VA) enlargement.

RESULTS

Among 555 ears, 312 (57.8%) ears had ABG; approximately 94% of the patients' bone-conduction hearing is almost completely lost at frequencies of 2 and 4 kHz. There was no linear correlation between age and bone-conduction threshold (p > 0.05). ABG did not significantly differ according to the degree of VA enlargement and number of SLC26A4 allele mutations (p > 0.05).

CONCLUSIONS AND SIGNIFICANCE

Among patients with EVA, ABG is mainly produced at low frequencies and is not significantly correlated with age, size of the VA opening or SLC26A4 genes, which could be attributed to the biomechanical effects.

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.

[Emphysema after cochlear implantation - risk factors and therapeutic options]

OBJECTIVE

In case of cochlear implantation seroma, hematoma, local wound infections or vertigo are rare but typical complications. In contrast, emphysema is seldom reported. They can occur after cochlear implantation both in the postoperative healing phase and years later. A therapeutic algorithm does not yet exist.

METHODS

We report on 3 patients with subcutaneous emphysema in the area of the receiver-stimulator. An unsystematic review of the literature of cases with emphysema after cochlear implantation highlights possible risk factors and the therapeutic options.

RESULTS

The 3 cases developed subcutaneous emphysema 2-11 month after cochlear implantation due to nose blowing or CPAP therapy in obstructive sleep apnea. The current literature reports another 35 cases of emphysema after cochlear implantation. Air insufflation via the Eustachian tube is the most frequently described cause. Diseases of the nose and sinuses, tube dysfunction and obstructive sleep apnea are potential risk factors. Pressure bandage, puncture, tympanic tubes, and surgical revision are common treatments.

CONCLUSIONS

Most emphysema can be controlled by conservative methods such as pressure bandaging and behavioral instruction. Punctures should be avoided due to the risk of upcoming infections. The prophylactic use of antibiotics seems dispensable. Surgical revision should be considered especially in cases of pneumocephalus with suspected leakage in the dura. The coverage of the mastoidectomy by a bony cap can be precautious and beneficial in cases with risk factors.

Outcomes of Acoustic and Linguistic Performances Following Cochlear Implantation in Large Vestibular Aqueduct Syndrome (LVAS)

AIM

This study aims to collate the outcomes in acoustic and linguistic performances after cochlear implantation in LVAS.

METHODS

In a hospital-based prospective interventional study, seven prelingual children with bilateral profound sensorineural hearing loss (SNHL) with LVAS were recruited. They underwent unilateral cochlear implantation between December 2013 and December 2015 in the Department of Otorhinolaryngology and Head Neck Surgery at a tertiary care center. Outcomes of auditory and speech performances were assessed in the form of revised categories of auditory perception (CAP), infant toddler meaningful auditory integration scale (IT-MAIS) and speech intelligibility rating (SIR) scores preoperatively, at one and two years follow up.

RESULTS

The mean age of implantation was 4 years. The median revised CAP, IT-MAIS, and SIR scores after one and two years of follow-up were 6, 27, 3, and 11, 36, 5 respectively. The mean follow-up duration was 21.3 months.

CONCLUSION

Pre op median revised CAP, IT-MAIS, and SIR scores of 0, 1, 1 showed improvement to 11, 36, 5 at two years follow up which was statistically significant. Hence, we conclude that good functional outcomes post-operatively advocate the significance of cochlear implantation in LVAS.

[Correlation of temporal bone HRCT, SLC26A4 gene and hearing loss in enlarged vestibular aqueduct]

Objective:To explore the correlation between high-resolution computed tomography（HRCT） of temporal bones, SLC26A4 gene mutation and hearing loss in patients with enlarged vestibular aqueduct（EVA）. Methods:The medical records of 257 subjects hospitalized for moderate to severe sensorineural hearing loss in the Department of Otolaryngology Head and Neck Surgery, Hainan General Hospital between May 2018 to 2021 were retrospectively reviewed. All included cases received audiological examination, HRCT scanning of temporal bones and SLC26A4 gene sequencing. According to the Valvassori standard, cases with the diameter from the common peduncle of the semicircular canal to the midpoint of the outer orifice of the vestibular aqueduct（MP） over 1.5 mm, or the diameter of the outer orifice of the vestibular aqueduct（OP） more than 2.0 mm were diagnosed as EVA. There were 22 cases（44 ears） of EVA in the study, aged between 6 months to 17 years old. Based on the hearing changes at birth and during growth, 18 ears of which were classified into the stable hearing group, while the other 26 ears in the unstable group. Moreover, all involved cases were grouped by MP（1.5 to <3.0 mm and ≥3.0 mm） and OP（2.0 to <4.0 mm and ≥4.0 mm）. SPSS 25.0 software was applied in the study. The correlation between hearing loss and MP and OP was analyzed. The results of HRCT of temporal bones and SLC26A4 gene sequencing were compared as well. Results:Though the size of MP and OP was not statistically different between the stable and hearing groups in EVA ears（P>0.05）, it was significantly correlated with the severity of hearing loss（P<0.05）. Of the 22 EVA patients diagnosed by HRCT, 21 were positive for SLC26A4 gene mutation. The positive rate of EVA by SLC26A4 gene sequencing was highly consistent with HRCT（Kappa=0.975）. Conclusion:The size of MP and OP in EVA patients was related to the degree of hearing loss, but not to the stable nature of hearing loss. Temporal bone HRCT scanning and SLC26A4 gene sequencing are highly consistent in the diagnosis of EVA. The latter has no radiation and can be combined with hearing screening for early diagnosis of EVA.

Hearing loss patterns in enlarged vestibular aqueduct syndrome: Do fluctuations have clinical significance?

OBJECTIVES

To reveal hearing loss patterns in patients with enlarged vestibular aqueduct (EVA) syndrome according to demographic and clinical characteristics.

METHODS

A retrospective, longitudinal study design was utilized to identify patients with EVA. Ears of patients were categorized into one of four cohorts: progressive fluctuating, progressive non-fluctuating, stable fluctuating, and stable non-fluctuating patterns. Pairwise and group comparisons were performed with non-parametric tests to assess vestibular aqueduct (VA) morphology, clinical, and demographic variables between hearing loss pattern cohorts. Rates of hearing loss in the subgroups were determined utilizing a mixed linear effects model.

RESULTS

44 patients (25 female, 19 male, median diagnosis age: 8.06 years) met inclusion criteria. 16 individuals demonstrated unilateral EVA and 29 had bilateral EVA, resulting in 74 total ears with EVA. Amongst the four cohorts, differences in operculum widths amongst groups were statistically significant (p = 0.049) while VA midpoint widths were not (p = 0.522). Progressive hearing loss ears without fluctuations demonstrated a 3.20 dB per year (p < 0.001) progression while progressive hearing loss ears with fluctuations reported a rate of 3.52 dB loss per year (p < 0.001).

CONCLUSION

Hearing fluctuations occur similarly in EVA patients with stable and progressive hearing loss. With the exception of increased rates of hearing loss progression for fluctuating progressive hearing loss patients, vestibular aqueduct morphology, demographic, and clinical characteristics commonly reported are likely not strong predictors for whether patients will or will not experience fluctuating patterns of hearing loss.

Prediction of Hearing Prognosis of Large Vestibular Aqueduct Syndrome Based on the PyTorch Deep Learning Model

In order to compare magnetic resonance imaging (MRI) findings of patients with large vestibular aqueduct syndrome (LVAS) in the stable hearing loss (HL) group and the fluctuating HL group, this paper provides reference for clinicians' early intervention. From January 2001 to January 2016, patients with hearing impairment diagnosed as LVAS in infancy in the Department of Otorhinolaryngology, Head and Neck Surgery, Children's Hospital of Fudan University were collected and divided into the stable HL group (n = 29) and the fluctuating HL group (n = 30). MRI images at initial diagnosis were collected, and various deep learning neural network training models were established based on PyTorch to classify and predict the two series. Vgg16_bn, vgg19_bn, and ResNet18, convolutional neural networks (CNNs) with fewer layers, had favorable effects for model building, with accs of 0.9, 0.8, and 0.85, respectively. ResNet50, a CNN with multiple layers and an acc of 0.54, had relatively poor effects. The GoogLeNet-trained model performed best, with an acc of 0.98. We conclude that deep learning-based radiomics can assist doctors in accurately predicting LVAS patients to classify them into either fluctuating or stable HL types and adopt differentiated treatment methods.

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.

Rare Disorders of the Vestibular Labyrinth: of Zebras, Chameleons and Wolves in Sheep's Clothing

The differential diagnosis of vertigo syndromes is a challenging issue, as many - and in particular - rare disorders of the vestibular labyrinth can hide behind the very common symptoms of "vertigo" and "dizziness". The following article presents an overview of those rare disorders of the balance organ that are of special interest for the otorhinolaryngologist dealing with vertigo disorders. For a better orientation, these disorders are categorized as acute (AVS), episodic (EVS) and chronic vestibular syndromes (CVS) according to their clinical presentation. The main focus lies on EVS sorted by their duration and the presence/absence of triggering factors (seconds, no triggers: vestibular paroxysmia, Tumarkin attacks; seconds, sound and pressure induced: "third window" syndromes; seconds to minutes, positional: rare variants and differential diagnoses of benign paroxysmal positional vertigo; hours to days, spontaneous: intralabyrinthine schwannomas, endolymphatic sac tumors, autoimmune disorders of the inner ear). Furthermore, rare causes of AVS (inferior vestibular neuritis, otolith organ specific dysfunction, vascular labyrinthine disorders, acute bilateral vestibulopathy) and CVS (chronic bilateral vestibulopathy) are covered. In each case, special emphasis is laid on the decisive diagnostic test for the identification of the rare disease and "red flags" for potentially dangerous disorders (e. g. labyrinthine infarction/hemorrhage). Thus, this chapter may serve as a clinical companion for the otorhinolaryngologist aiding in the efficient diagnosis and treatment of rare disorders of the vestibular labyrinth.

Vestibular impairment in cochlear implanted children presenting enlarged vestibular aqueduct and enlarged endolymphatic sac

Enlarged vestibular aqueduct (EVA) is a common finding in tomodensitometry. When cranial MRI is performed, enlarged endolymphatic sac (EES) can also be found. Profound hearing loss is a common finding in these patients but a few studies have investigated vestibular function after cochlear implantation (CI) in EVA and EES patients. Our main objective was to find out whether in EVA children candidates to CI, a higher endolymphatic sac (ES) volume was predictive for higher rates of postsurgical vestibular complications.

METHODS

We retrospectively included EVA children who benefited from CI, during the last 2 years. Two groups were constituted according to the presence or not of a vestibular impairment (decrease in the VOR gain on the VHIT test on one of the semicircular canals and/or a loss of cVEMPs) 6 months after CI. Endolymphatic volume of both VA and ES was measured for each patient.

RESULTS

Fifteen patients were included. The mean endolymph volume was significantly higher in the impaired group (0.40 cm³ ± 0.23, range 0.08-0.70) than in the non-impaired group (0.11 cm³ ± 0.07, range 0.04-0.29; p = 0.029). Four children of the impaired group were followed during one year. At the end of vestibular rehabilitation, all children recovered a lateral canal function and a saccular function.

CONCLUSION

In EVA children, a combined EES appears to increase the risk of severe post CI vestibular impairment. To minimize this risk prior CI surgery, besides tomodensitometry, MRI measurement of the ES volume should be systematically performed.

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.

Progression of hearing loss and cochlear implantation in large vestibular aqueduct syndrome

OBJECTIVES

Large vestibular aqueduct syndrome (LVAS) is a congenital inner ear malformation that commonly results in progressive sensorineural hearing loss (SNHL) and cochlear implantation (CI). Though LVAS accounts for approximately 15% of pediatric SNHL, little is known regarding the rate and severity of SNHL in these patients. We sought to characterize the timing of SNHL progression to CI in patients with LVAS.

METHODS

We performed a retrospective chart review at our institution from 2000 to 2018 using ICD-10 "large vestibular aqueduct syndrome," and through identifying patients with CI who had LVAS. Demographic, surgical, and audiometric data were collected. Theoretical CI candidacy was approximated using a pure tone average (PTA) HL threshold of 70 dB.

RESULTS

Of 103 patients, 96 had bilateral LVAS, and 7 had unilateral LVAS. Forty-one patients had bilateral implants, 52 had unilateral implants, and 10 were not implanted. The mean age at first implant was 8.62 years old [95%CI = 6.75,10.49], the mean age at second implant was 12.24 years old [95%CI = 8.33,16.15], and the mean time between implants was 4.37 years [95%CI = 3.02,5.73]. LVAS patients reached HL threshold of 70 dB at a mean age of 5.16 years old (SD = 3.04) for the "worse ear" and 9.08 years old (SD = 4.96) for the "better ear."

CONCLUSIONS

LVAS patients are a heterogenous population of patients, in which some may undergo progression of HL and some may not. Further, there may be a discrepancy in the timing between patients' theoretical CI candidacy and when they undergo CI. In order to optimize timing of CI, individual monitoring and close observation of LVAS patients is recommended.

Detailed MR imaging assessment of endolymphatic hydrops in patients with SLC26A4 mutations

OBJECTIVE

Mutations in SLC26A4 represent the second most common mutations in deafness patients. The majority of patients with SLC26A4 mutations have a large vestibular aqueduct (LVA). Recently, some reports showed the presence of endolymphatic hydrops (ELH) in patients with LVA on the basis of high-resolution enhanced 3T-MRI. However, detailed evaluation has not been performed. We provide the first report on ELH in LVA patients with biallelic SLC26A4 mutations. In this study, we focused on 1) the findings of ELH in LVA patients with biallelic SLC26A4 mutations, and 2) the findings of the endolymphatic duct (ED) and endolymphatic sac (ES) by using two different gadodimide (Gd) enhancement methods.

SUBJECTS AND METHODS

Five patients with SLC26A4 mutations underwent enhanced 3T-MRI using the intratympanic (IT) or intravenous (IV) injection of Gd for the diagnosis ELH.

RESULTS

All of the patients had ELH in at least one ear. ELH was identified in the vestibule (8/10 ears) as well as in the cochlea (7/10 ears). With regard to the ED and ES, all ears for which MRI was performed with an IT injection of Gd had black areas in the ES or VA or both; however, all of the ears receiving an IV injection had no black areas and were well enhanced.

CONCLUSIONS

A majority of the patients had severe ELH in the cochleo-vestibular endolymph, with two different patterns observed in the MRI findings of the ED and ES.

Sensorineural Hearing Loss in the Nonimplanted Ear Following Cochlear Implantation in a Patient With Bilateral Enlarged Vestibular Aqueducts

OBJECTIVE

To document the case of a patient with bilateral enlarged vestibular aqueducts who experienced sensorineural hearing loss in the nonimplanted ear following unilateral cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion and to highlight the need to counsel regarding the risk of potential hearing loss to the contralateral ear when preparing for cochlear implants in the setting of inner ear malformations.

PATIENTS

One patient with bilateral enlarged vestibular aqueducts in a tertiary referral center.

INTERVENTION(S)

Cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion.

MAIN OUTCOME MEASURE(S)

Bone conduction hearing thresholds, word recognition scores.

RESULTS

The patient underwent unilateral cochlear implantation, which was complicated by a perilymphatic gusher and necessitated placement of an intraoperative lumbar drain. On postoperative day 1, the patient reported hearing loss in the opposite ear. The word recognition score in the contralateral ear dropped from 24% at preimplantation to 8% at 2-weeks postimplantation, and did not improve at 6 months postimplantation. Moreover, the bone conduction threshold at 1 kHz worsened from 20 dB preoperatively to no response at 75 dB (the limit of the testing equipment) at 2-weeks postoperatively and only partially improved to 40 dB at 6 months postimplantation.

CONCLUSION

As patients with inner ear malformations potentially have direct high-pressure anatomical connections between the perilymphatic spaces and the cerebrospinal fluid, they are at risk of hearing loss in the nonimplanted ear during cochlear implantation. This case highlights the need for potential additional patient counseling regarding this risk in the nonimplanted ear.

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.

Is CT or MRI the optimal imaging investigation for the diagnosis of large vestibular aqueduct syndrome and large endolymphatic sac anomaly?

BACKGROUND AND PURPOSE

We explored whether there was a difference between measurements obtained with CT and MRI for the diagnosis of large vestibular aqueduct syndrome or large endolymphatic sac anomaly, and whether this influenced diagnosis on the basis of previously published threshold values (Valvassori and Cincinnati). We also investigated whether isolated dilated extra-osseous endolymphatic sac occurred on MRI. Secondary objectives were to compare inter-observer reproducibility for the measurements, and to investigate any mismatch between the diagnoses using the different criteria.

MATERIALS/METHODS

Subjects diagnosed with large vestibular aqueduct syndrome or large endolymphatic sac anomalies were retrospectively analysed. For subjects with both CT and MRI available (n = 58), two independent observers measured the midpoint and operculum widths. For subjects with MRI (± CT) available (n = 84), extra-osseous sac widths were also measured. Results There was no significant difference between the width measurements obtained with CT versus MRI. CT alone diagnosed large vestibular aqueduct syndrome or large endolymphatic sac anomalies in 2/58 (Valvassori) and 4/58 (Cincinnati), whilst MRI alone diagnosed them in 2/58 (Valvassori). There was 93% CT/MRI diagnostic agreement using both criteria. Only 1/84 demonstrated isolated extra-osseous endolymphatic sac dilatation. The MRI-based LVAS/LESA diagnosis was less dependent on which criteria were used. Midpoint measurements are more reproducible between observers and between CT/MR imaging modalities.

CONCLUSION

Supplementing MRI with CT results in additional diagnoses using either criterion, however, there is no net increased diagnostic sensitivity for CT versus MRI when applying the Valvassori criteria. Isolated enlargement of the extra-osseous endolymphatic sac is rare.

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.

Vestibular Dysfunction in Patients with Enlarged Vestibular Aqueduct

OBJECTIVE

Enlarged vestibular aqueduct (EVA) is the most common inner ear malformation. While a strong correlative relationship between EVA and hearing loss is well established, its association with vestibular dysfunction is less well understood. In this study, we examine the effects of EVA on the vestibular system in patients with EVA.

STUDY DESIGN

Prospective, cross-sectional study of a cohort ascertained between 1999 and 2013.

SETTING

National Institutes of Health Clinical Center, a federal biomedical research facility.

SUBJECTS AND METHODS

In total, 106 patients with unilateral or bilateral EVA, defined as a midpoint diameter greater than 1.5 mm, were referred or self-referred to participate in a study of the clinical and molecular aspects of EVA. Clinical history was ascertained with respect to the presence or absence of various vestibular signs and symptoms and history of head trauma. Videonystagmography (VNG), cervical vestibular evoked myogenic potential (cVEMP), and rotational vestibular testing (RVT) were performed to assess the vestibular function.

RESULTS

Of the patients with EVA, 45% had vestibular signs and symptoms, and 44% of tested patients had abnormal VNG test results. An increased number of vestibular signs and symptoms was correlated with the presence of bilateral EVA (P = .008) and a history of head injury (P < .001). Abnormal VNG results also correlated with a history of head injury (P = .018).

CONCLUSION

Vestibular dysfunction is common in patients with EVA. However, not all patients with vestibular signs and symptoms have abnormal vestibular test results. Clinicians should be aware of the high prevalence of vestibular dysfunction in patients with 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.

Slc26a4-insufficiency causes fluctuating hearing loss and stria vascularis dysfunction

SLC26A4 mutations can cause a distinctive hearing loss phenotype with sudden drops and fluctuation in patients. Existing Slc26a4 mutant mouse lines have a profound loss of hearing and vestibular function, with severe inner ear malformations that do not model this human phenotype. In this study, we generated Slc26a4-insufficient mice by manipulation of doxycycline administration to a transgenic mouse line in which all Slc26a4 expression was under the control of doxycycline. Doxycycline was administered from conception to embryonic day 17.5, and then it was discontinued. Auditory brainstem response thresholds showed significant fluctuation of hearing loss from 1 through 3months of age. The endocochlear potential, which is required for inner ear sensory cell function, correlated with auditory brainstem response thresholds. We observed degeneration of stria vascularis intermediate cells, the cells that generate the endocochlear potential, but no other abnormalities within the cochlea. We conclude that fluctuations of hearing result from fluctuations of the endocochlear potential and stria vascularis dysfunction in Slc26a4-insufficient mouse ears. This model can now be used to test potential interventions to reduce or prevent sudden hearing loss or fluctuation in human patients. Our strategy to generate a hypomorphic mouse model utilizing the tet-on system will be applicable to other diseases in which a hypomorphic allele is needed to model the human phenotype.

SLC26A4 mutation testing for hearing loss associated with enlargement of the vestibular aqueduct

Pendred syndrome (PS) is characterized by autosomal recessive inheritance of goiter associated with a defect of iodide organification, hearing loss, enlargement of the vestibular aqueduct (EVA), and mutations of the SLC26A4 gene. However, not all EVA patients have PS or SLC26A4 mutations. Two mutant alleles of SLC26A4 are detected in 1/4 of North American or European EVA populations, one mutant allele is detected in another 1/4 of patient populations, and no mutations are detected in the other 1/2. The presence of two mutant alleles of SLC26A4 is associated with abnormal iodide organification, increased thyroid gland volume, increased severity of hearing loss, and bilateral EVA. The presence of a single mutant allele of SLC26A4 is associated with normal iodide organification, normal thyroid gland volume, less severe hearing loss and either bilateral or unilateral EVA. When other underlying correlations are accounted for, the presence of a cochlear malformation or the size of EVA does not have an effect on hearing thresholds. This is consistent with observations of an Slc26a4 mutant mouse model of EVA in which hearing loss is independent of endolymphatic hydrops or inner ear malformations. Segregation analyses of EVA in families suggest that the patients carrying one mutant allele of SLC26A4 have a second, undetected mutant allele of SLC26A4, and the probability of a sibling having EVA is consistent with its segregation as an autosomal recessive trait. Patients without any mutations are an etiologically heterogeneous group in which siblings have a lower probability of having EVA. SLC26A4 mutation testing can provide prognostic information to guide clinical surveillance and management, as well as the probability of EVA affecting a sibling.

The relationship between vestibular aqueduct diameter and sensorineural hearing loss is linear: a review and meta-analysis of large case series

INTRODUCTION

Inner ear homeostasis is dependent on the vestibular aqueduct and its content, the endolymphatic duct. Narrow and enlarged vestibular aqueducts have both been associated with hearing loss in Ménière's and large vestibular aqueduct syndromes. This review investigated the correlation between vestibular aqueduct diameter and pure tone average, and the effect of measurement site (i.e. the midpoint or the external aperture).

MATERIALS AND METHODS

A systematic review of the literature and meta-analysis of large case series published on the Allied and Complementary Medicine, British Nursing Index, Cumulative Index to Nursing and Allied Health, Embase, Health Business Elite, Health Management Information Consortium, Medline, PsycInfo and PubMed databases. References and personal books were also scrutinised.

RESULTS

A linear relationship between vestibular aqueduct diameter and hearing loss was observed, with a projected increase of 6 dBHL per unit of vestibular aqueduct diameter (95 per cent confidence interval, 2-10; p = 0.003). This relationship was independent of measurement site.

DISCUSSION

This dose-dependent or linear relationship supports the role of flow and/or pressure change as aetiological factors in the pathogenesis of hearing loss, as per Poiseuille's law. This aetiological association is strengthened by the fact that the observed relationship is independent of measurement site.

Hemorrhage in the endolymphatic sac: a cause of hearing fluctuation in enlarged vestibular aqueduct

OBJECTIVE

Most of the patients with enlarged vestibular aqueduct (EVA) experience sudden hearing deterioration, but the exact mechanism is unclear. We analyzed magnetic resonance (MR) images and the cellular components of endolymph obtained from the endolymphatic sac in patients with EVA, in order to demonstrate the cause of sudden hearing loss.

METHODS

A total of 25 patients (50 ears) with EVA, who had severe to profound hearing loss, were included in this retrospective clinical study. MR examinations were performed by a 3.0-T MR system using an 8-channel sensitivity-encoding head coil. We analyzed endolymphatic fluid harvested from the endolymphatic sac during cochlear implantations in four patients.

RESULTS

The area of low signal intensity in the endolymphatic sac was observed on T2-weighted MR images for 15 of 50 ears. This area was observed more frequently in patients who experienced recent sudden hearing loss (10/12, 83%) than those with stable hearing (5/38, 13%)(Fisher's exact test, p<0.001). In addition, this area showed high signal intensity on fluid attenuated inversion recovery images. Cytologic analysis of the aspirated endolymph from the endolymphatic sac in the patients with this area revealed many erythrocytes.

CONCLUSION

Our data suggests that hemorrhage in the endolymphatic sac could be a cause of sudden hearing deterioration in patients with EVA.

Cochlear implantation in children with labyrinthine anomalies and cochlear nerve deficiency: implications for auditory brainstem implantation

OBJECTIVES/HYPOTHESIS

Compare outcomes among children with inner ear malformations and/or cochlear nerve deficiency (CND) who have received a cochlear implant (CI).

STUDY DESIGN

Individual retrospective cohort study from 1993 to 2010.

METHODS

A select cohort of 76 children was identified. Imaging characteristics, operative findings, complications, mapping parameters, and performance were assessed. Comparisons among the different groups were undertaken.

RESULTS

Surgery was mostly uncomplicated. Nearly all children demonstrated behavioral responses to CI stimulation irrespective of inner ear morphology or the presence of CND. Children with CND had higher pure tone averages (PTAs) and required greater charge for stimulation than other malformation types. Open-set speech perception was achieved in 100% of children with incomplete partition-enlarged vestibular aqueduct (IP-EVA), 50% of those with hypoplastic malformations, and 19% of CND cases. Robust responses on eighth nerve compound action potential (ECAP) testing through the implant was associated with higher levels of speech perception. Manually supplemented communication strategies were more common among children with hypoplastic malformations (69%) and CND (95%) than those with IP-EVA (18%).

CONCLUSIONS

Children with IP-EVA malformations have an excellent prognosis for developing open-set speech perception and using oral communication modes following CI. On the contrary, children with severe malformations or CND may have elevated charge requirements for attaining sound detection alone. These children's prognosis for obtaining open-set speech understanding, using exclusive oral communication, and participating in mainstream education is more limited. These findings have important implications for considering alternative forms of intervention such as auditory brainstem implantation and/or supplementation with visually based communication strategies.