Evaluation of the radiological criteria to diagnose large vestibular aqueduct syndrome

Study on characteristics of wideband acoustic immittance in patients with Inner Ear Malformations

OBJECTIVE

To compare the differences in wideband absorbance and the resonance frequency (RF) between patients with inner ear malformations and normal control, and to explore the auditory diagnostic value of wideband acoustic immittance (WAI).

METHODS

A total of 38 patients (59 ears) with enlarged vestibular aqueduct (EVA), 13 patients (14 ears) with incomplete partition type I (IP-I) and 13 patients (26 ears) with incomplete partition type II (IP-II) were included. 50 normal control (100 ears). All subjects underwent WAI tests to compare the absorbance configuration and resonance frequency.

RESULTS

All the group showed lower absorbance at ambient pressure than at peak pressure in certain frequencies under 2000Hz. Under 1000Hz, the absorbance of EVA was higher than that of other groups. The average absorbance and highest absorbance of IP-I were the lowest(P＜0.05). However, IP-II and normal group had similarity on some characteristics. The three IEM groups mainly different at low and high frequencies, but not at medium frequencies. The highest absorbance of all the groups were appeared around 3000Hz. The RF of all the groups from low to high were EVA＜IP-II＜normal control＜IP-I, and the lowest was EVA(P＜0.05).

CONCLUSION

Inner ear malformations can affect energy absorbance and RF. WAI is sensitive and non-invasive to provide useful information about inner ear status and facilitate detection of ear pathology.

Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Classifying the Large Vestibular Aqueduct: Morphometry to Audiometry

OBJECTIVE

Large vestibular aqueduct (LVA) is the most common inner ear dysplasia identified in patients with hearing loss. Our objective was to systematically quantify LVA morphologies and correlate imaging findings with established audiometric outcomes.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

Patients with large vestibular aqueduct identified radiographically, with or without hearing loss.

INTERVENTIONS

Diagnostic only.

MAIN OUTCOME MEASURES

Vestibular aqueduct (VA) width at midpoint, width at external aperture, and length were measured on cross-sectional imaging. Morphology was classified as type I (borderline), type II (tubular), or type III (funneled). Audiometric endpoints included air/bone conduction, pure tone averages, and air-bone gaps at 250 and 500 Hz. Statistical associations were evaluated using linear regression models, adjusted for age at first audiogram and sex.

RESULTS

One hundred seventeen patients (197 ears) were included, with mean age at first audiogram of 22.2 years (standard deviation, 21.7 yr). Imaging features associated with poor audiometric outcomes were increasing VA width at midpoint and external aperture, decreasing VA length, dilated extraosseous endolymphatic sac, cochleovestibular malformations, and increasing VA type (III > II > I).

CONCLUSIONS

Quantitative LVA measurements and a standardized morphologic classification system aid in prediction of early audiometric endpoints.

Assessing the clinical utility of volumetric HRCT in pediatric enlarged vestibular aqueduct related hearing loss

OBJECTIVES

|The aim of this study was to evaluate the use of volumetric HRCT measurements in the diagnosis of enlarged vestibular aqueduct syndrome (EVAS) and describe the association of this novel radiographic approach with clinical hearing outcomes. We hypothesized that volumetric measurements may have stronger correlation to hearing loss given the anatomic variability of the vestibular aqueduct in linear measurements.

METHODS

A retrospective study design was used, including 51 patients that fit the inclusion criteria for the study for a total of 81 ears. 3D volumes were calculated using the MIM Software platform (MIM Software Inc.) from semiautomatic segmentation of the VA across individual slices on CT scan. Air and bone conduction data was collected from medical records with the air-bone gap being calculated from these data. Univariate and multivariate analyses were conducted to determine if volumetric VA size correlated with hearing loss outcomes.

RESULTS

Out of the study population, 30 subjects (58.8%) demonstrated bilateral EVA. Average VA size estimated by volumetric CT methodology was 0.035 mm³; sd = 0.025 mm³. Volumetric measurements significantly correlated to both midpoint length and operculum size. Multivariate analysis adjusting for age, race, and gender demonstrated significant correlation between volumetric VA size and both low and high frequencies for PTA Air (p = 0.009; 0.010) and PTA Bone (p = 0.027; 0.002), respectively. Of note, the coefficient values for volumetric data were higher than linear measurements showing a potentially stronger correlation, albeit with high variability. Volumetric size was not significantly correlated to air-bone gap at either low or high frequency (p = 0.335; 0.062).

CONCLUSION

Our results indicate that volumetric CT measurements of the VA may be a valid and viable new method for assessing EVAS patients. In our study, volumetric VA measurements demonstrated a strong correlation across both air and bone conduction at both frequency ranges measured, with potentially greater correlative strength than linear measurements.

Critérios para a classificação do grau da perda auditiva e proteção social de pessoas com essa deficiência

RESUMO Objetivos: identificar critérios adotados nacional e internacionalmente para classificação do grau da perda auditiva, compará-los com o estabelecido na legislação brasileira e discutir as possíveis consequências dessa legislação para a proteção social de Pessoas com Deficiência (PcD) auditiva. Métodos: realizou-se uma revisão narrativa para a identificação dos critérios utilizados nessa classificação. A busca foi realizada em abril de 2020, a partir das plataformas BVS e PUBMED. Foram incluídos estudos publicados entre 2015 e 2019, em inglês, espanhol e português, sobre pesquisas primárias realizadas com seres humanos e menção explícita aos critérios utilizados para a classificação do grau da perda auditiva. Revisão da Literatura: observou-se que há uma predileção pela média entre as frequências de 0,5, 1, 2 e 4 kHz. A legislação brasileira não segue esse critério, o que pode ser uma barreira para o acesso das PcD auditiva aos programas de proteção social. Considerações Finais: não há consenso sobre qual é o melhor critério, todavia há predominância de utilização do considerado mais abrangente para a avaliação auditiva, que não é o legalmente adotado no Brasil. É necessário um debate sobre o critério legal brasileiro, a fim de promover os direitos sociais instituídos para parte das PcD auditiva no Brasil.

Criteria to classify degrees of hearing loss and the social protection of people with this disability

ABSTRACT Purpose: to identify criteria used nationally and internationally to classify degrees of hearing loss, compare them with what is established in the Brazilian law, and discuss possible consequences of such a law on the social protection of people with hearing loss. Methods: a narrative review was conducted to identify the criteria used in this classification, by searching the platforms VHL and PubMed in April 2020. It included primary human research explicitly mentioning the criteria used to classify the degree of hearing loss, published between 2015 and 2019 in English, Spanish, and Portuguese. Literature Review: there is a preference for the four-frequency mean at 0.5, 1, 2, and 4 kHz. The Brazilian law does not follow these criteria, which may pose a barrier to people with hearing loss, hindering their access to social protection programs. Final Considerations: there is no consensus on the best criteria, although the most encompassing ones in hearing assessment predominate - which are not the ones legally used in Brazil. It is necessary to debate the Brazilian legal criteria to ensure existing social rights to part of people with hearing loss in Brazil.

Clinical Implication of Caloric and Video Head Impulse Tests for Patients With Enlarged Vestibular Aqueduct Presenting With Vertigo

Background: By examining the clinical features and results of video head impulse test (vHIT) and caloric tests in patients with enlarged vestibular aqueduct (EVA) presenting with vertigo, we aimed to investigate the function of angular vestibulo-ocular reflex (VOR) and its clinical implications.

Methods: Nine patients with EVA manifesting with vertigo were enrolled. The medical history, audiological examination, imaging, and the results of the caloric test and the vHIT were analyzed.

Results: Of the nine patients with EVA (eight bilateral and one unilateral case), five were pediatric cases. All 17 ears exhibited sensorineural hearing loss (SNHL). Enlarged vestibular aqueduct patients can present with recurrent (seven cases) or single (two cases) vertigo attack, trauma-induced (two cases), or spontaneous (seven cases) vertigo. Diminished caloric responses were observed in 77.8% (7/9) of the patients (four cases unilaterally and three bilaterally), while unilateral abnormal vHIT results in 11.1% (1/9) patients. Abnormal caloric and normal horizontal vHIT responses were found in 66.7% (6/9) of EVA patients.

Conclusions: Vestibular manifestations in EVA are diverse. Enlarged vestibular aqueduct patients with vertigo can present with a reduced caloric response and normal horizontal vHIT, and this pattern of angular VOR impairment was also found in other hydropic ear diseases.

Imaging of inner ear malformations: a primer for radiologists

In the multidisciplinary management of patients with inner ear malformations (IEMs), the correct diagnosis makes the differences in terms of clinical and surgical treatment. The complex anatomical landscape of the inner ear, comprising several small structures, makes imaging of this region particularly challenging for general radiologists. Imaging techniques are important for identifying the presence and defining the type of IEM and the cochlear nerve condition. High-resolution magnetic resonance imaging (MRI) sequences and high-resolution computed tomography (HRCT) are the mainstay imaging techniques in this area. Dedicated MRI and HRCT protocols play an important role in the diagnosis and treatment of patients with inner ear disease. The most suitable technique should be selected depending on the clinical setting. However, in cases of congenital malformation of the inner ear, these techniques should be considered complementary. Since prompt intervention has a positive impact on the treatment outcomes, early diagnosis of IEMs is very important in the management of deaf patients. This article reviews the key concepts of IEMs for clinical radiologists by focusing on recent literature updates, discusses the principal imaging findings and clinical implications for every IEM subgroup, thus providing a practical diagnostic approach.

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.

Nonsyndromic Congenital Causes of Sensorineural Hearing Loss in Children: An Illustrative Review

OBJECTIVE. The purpose of this article is to provide an illustrative review of nonsyndromic congenital causes of sensorineural hearing loss (SNHL) in children. CONCLUSION. Early recognition and treatment are essential in maximizing developmental outcomes in children with congenital SNHL. Because imaging plays an integral role in identifying underlying causes of SNHL, it is imperative that radiologists be able to recognize, describe, and appropriately categorize the spectrum of congenital inner ear malformations in children.

Investigation of DFNB4 SLC26A4 mutation in patients with enlarged vestibular aquaduct

OBJECTIVES

Mutations of the SLC26A4 gene causing enlarged vestibular aqueduct (EVA) syndrome have not yet been fully elucidated. The study aimed to investigate SLC26A4 mutations in patients with EVA syndrome in the Turkish population. Identifying these mutations may play an essential role in determining the prognosis, follow-up, and management options of these patients.

METHODS

Whole exome sequencing and/or Sanger sequencing of SLC26A4 in 22 patients with sensorineural hearing loss associated with isolated EVA without inner ear anomalies, and 22 controls were performed.

RESULTS

Twenty-two patients and 22 control subjects were included in the study. The onset of hearing loss was pre-lingual in 15 patients, and post-lingual in 7. The mean (standard deviation) vestibular aqueduct width of the patients was 3.23 mm (1.28). Twenty SLC26A4 variants, 15 of them unique, were identified in 22 patients. Among them, seven variants were heterozygous, and 13 were homozygous. The variants p.E37X (c.109G > T), p.Y27H (c.79T > C), p.C706Y (c.2117G > A) have not been previously reported.

CONCLUSION

The detection of rare and previously unreported mutations in our study showed that studies with a larger number of patients with EVA might reveal more role of the SLC26A4 gene. Besides, to understand the etiopathogenesis of the disease, other related genes also should be investigated.

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.

Vestibular Aqueduct Midpoint Width and Hearing Loss in Patients With an Enlarged Vestibular Aqueduct

Importance

Elucidating the relationship between vestibular aqueduct size and hearing loss progression may inform the prognosis and counseling of patients who have an enlarged vestibular aqueduct (EVA).

Objectives

To examine the association between vestibular aqueduct size and repeated measures of hearing loss.

Design, Setting, and Participants

For this retrospective medical record review, 52 patients with a diagnosis of hearing loss and radiologic diagnosis of EVA according to the Valvassori criterion were included. All available speech reception threshold and word recognition score data was retrieved; mixed-effects models were constructed where vestibular aqueduct size, age at diagnosis of hearing loss, and time since diagnosis of hearing loss were used to predict repeated measures of hearing ability. This study was performed at an academic tertiary care center.

Exposures

Variable vestibular aqueduct size, age at first audiogram, length of time after first audiogram.

Main Outcomes and Measures

Speech reception threshold (dB) and word recognition score (%) during routine audiogram.

Results

Overall, 52 patients were identified (29 females [56%] and 23 males [44%]; median age at all recorded audiograms, 7.8 years) with a total of 74 ears affected by EVA. Median (range) vestibular aqueduct size was 2.15 (1.5-5.9) mm, and a median (range) of 5 (1-18) tests were available for each patient. Each millimeter increase in vestibular aqueduct size above 1.5 mm was associated with an increase of 17.5 dB in speech reception threshold (95% CI, 7.2 to 27.9 dB) and a decrease of 21% in word recognition score (95% CI, -33.3 to -8.0 dB). For each extra year after a patient's first audiogram, there was an increase of 1.5 dB in speech recognition threshold (95% CI, 0.22 to 3.0 dB) and a decrease of 1.7% in word recognition score (95% CI, -3.08 to -0.22 dB).

Conclusions and Relevance

Hearing loss in patients with an EVA is likely influenced by vestibular aqueduct midpoint width. When considering hearing loss prognosis, vestibular aqueduct midpoint width may be useful for the clinician who counsels patients affected by EVA.

Contrasting results of tests of peripheral vestibular function in patients with bilateral large vestibular aqueduct syndrome

OBJECTIVE

To analyze and summarize the effect of bilateral large vestibular aqueducts in peripheral vestibular organ function.

METHODS

Eighteen patients with bilateral large vestibular aqueduct syndrome (LVAS; Study Group) and 18 healthy volunteers (Control Group) were investigated using audiometry, caloric test, sensory organization test (SOT), and vestibular-evoked myogenic potential (VEMP) tests.

RESULTS

All 18 patients (36 ears) exhibited sensorineural hearing loss. For cervical VEMP (cVEMP), the Study Group showed lower thresholds (Study Group vs.

CONTROL GROUP

71.4vs. 75.3dBnHL; p=0.006), N1 latencies (24.1vs. 25.2ms; p=0.026) and shorter P1 (15.3vs. 16.6ms; p=0.003), and higher amplitudes (400.7vs. 247.2µV; p<0.001) than the Control Group. For ocular VEMP (oVEMP), the Study Group had lower thresholds (79.3vs. 81.8dBnHL; p=0.046) and higher amplitudes (40.6vs. 14.4µV; p<0.001) than the Control Group. Fourteen of 16 patients (87.5%) who completed caloric tests had abnormal results, and 10 of 18 patients (55.6%) exhibited abnormal results in SOTs.

CONCLUSIONS

The hyperfunction of vestibular test in otolithic organs and the hypofunction of vestibular test in semicircular canals, as well as the dysfunction in the balance test were demonstrated in patients with LVAS.

SIGNIFICANCE

Our findings can help clinicians gain a better understanding of the characteristics of vestibular organ function in patients with LVAS, which can facilitate optimal targeted treatment.

Identification of SLC26A4 mutations p.L582LfsX4, p.I188T and p.E704K in a Chinese family with large vestibular aqueduct syndrome (LVAS)

Large vestibular aqueduct syndrome (LVAS) is a type of hearing loss characterized by an autosomal recessive inheritance. LVAS has been shown to be associated with mutations in SLC26A4 gene. In the present study, we report the clinical, genetic and molecular characterization of a Chinese family with LVAS. By using the targeted sequence capture and next-generation sequencing, we identified heterozygous mutations of SLC26A4 p.I188T (c.563T > C), p.L582LfsX4 (c.1746 delG) and p.E704K (c.2110G > A) in the affected individual of this family, of which SLC26A4 p.E704K is a novel mutation associated with LVAS. By tracing the transmission and functional prediction of these mutations in the pedigree, the heterozygous mutations of p.I188T, p.L582LfsX4 and p.E704K in SLC26A4 gene were responsible for the LVAS of the affected individual. This is the first case of LVAS caused by these mutations.