Angular Trajectory of the Vestibular Aqueduct in a Cohort of Chinese Patients with Unilateral Ménière's Disease: Association with Other Imaging Indices and Clinical Profiles.

OBJECTIVE: We aimed to investigate the association between the angular trajectory of the vestibular aqueduct (ATVA) with other radiological parameters of temporal bone and clinical characteristics in patients with Ménière's disease (MD). METHODS: A total of 125 unilateral MD patients and 118 controls were enrolled. Computer tomography (CT)-based radiological parameters included ATVA, vestibular aqueduct (VA) visibility, VA morphology, the vertical part of the posterior semicircular canal-the posterior fossa distance (PPD), and peri-VA pneumatization. The clinical characteristics of MD patients included gender, age of diagnosis/onset, disease duration, migraine history, clinical staging, and the results of audio-vestibular tests. The radiological parameters and clinical characteristics in MD patients were compared. RESULTS: Compared with control ears, ATVA ≥ 140° was more prevalent and ATVA ≤ 120° was less frequent in the MD-affected side. For the MD-affected side, MD patients with ATVA ≥ 140° exhibited more severe VA invisibility and obliteration and higher male preponderance than those with ATVA ≤ 120°. Other radio-clinical features did not differ between these two subgroups. CONCLUSION: In the current study, ATVA ≥ 140°, an indicator of a hypoplastic endolymphatic sac, was found in approximately one-third of the affected and unaffected ears of patients with MD, as well as in a minority of controls. This suggests that the indices may be a predisposing factor rather than a specific marker for the MD ear. The male preponderance in MD patients with hypoplastic ES suggests a gender difference in the anatomical factors for MD pathogenesis.

Audio-Vestibular Evaluation of Pediatric Pseudo-Conductive Hearing Loss: Third Window Syndromes.

Conductive hearing loss caused by external or middle ear problems prevents the transmission of sound waves from the external auditory canal to the cochlea, and it is a common condition, especially in pediatric patients aged 1-5 years. The most common etiological factors are otitis media and cerumen during childhood. In some patients, external and middle ear functions and structures may be normal bilaterally despite the air-bone gap on the audiogram. This condition, which is often a missed diagnosis in children, is defined as a pseudo-conductive hearing loss (PCHL) caused by third window syndromes (TWSs) such as semicircular canal dehiscence, inner ear malformations with third window effect, and perilymphatic fistula. In this review of the literature, the authors emphasize the pitfalls of pediatric audio-vestibular evaluation on TWSs as well as the key aspects of this evaluation for the differential diagnosis of PCHL brought on by TWSs. This literature review will provide audiologists and otologists with early diagnostic guidance for TWSs in pediatric patients.

Validating the splicing effect of rare variants in the SLC26A4 gene using minigene assay.

BACKGROUND: The SLC26A4 gene is the second most common cause of hereditary hearing loss in human. The aim of this study was to utilize the minigene assay in order to identify pathogenic variants of SLC26A4 associated with enlarged vestibular aqueduct (EVA) and hearing loss (HL) in two patients. METHODS: The patients were subjected to multiplex PCR amplification and next-generation sequencing of common deafness genes (including GJB2, SLC26A4, and MT-RNR1), then bioinformatics analysis was performed on the sequencing data to identify candidate pathogenic variants. Minigene experiments were conducted to determine the potential impact of the variants on splicing. RESULTS: Genetic testing revealed that the first patient carried compound heterozygous variants c.[1149 + 1G > A]; [919-2 A > G] in the SLC26A4 gene, while the second patient carried compound heterozygous variants c.[2089 + 3 A > T]; [919-2 A > G] in the same gene. Minigene experiments demonstrated that both c.1149 + 1G > A and c.2089 + 3 A > T affected mRNA splicing. According to the ACMG guidelines and the recommendations of the ClinGen Hearing Loss Expert Panel for ACMG variant interpretation, these variants were classified as "likely pathogenic". CONCLUSIONS: This study identified the molecular etiology of hearing loss in two patients with EVA and elucidated the impact of rare variants on splicing, thus contributing to the mutational spectrum of pathogenic variants in the SLC26A4 gene.

Insidious Cases of Enlarged Vestibular Aqueduct (EVA) Syndrome Resembling Otosclerosis: Clinical Features for Differential Diagnosis and the Role of High-Resolution Computed Tomography in the Pre-Operative Setting.

BACKGROUND: Enlarged vestibular aqueduct (EVA) syndrome can mimic otosclerosis in adults, presenting with an air-bone gap (ABG) and even absent stapedial reflexes. The ABG in inner-ear disorders is currently the object of several authors' studies and seems to be related to a third mobile window (TMW) phenomenon. This can lead to misdiagnosis and inappropriate treatment. Given that it would be inappropriate and harmful to perform CT scans in all patients with a clinical diagnosis of otosclerosis, this study aims to highlight some clinical features useful for the differential diagnosis between otosclerosis and these rare cases of EVA presenting with an ABG, thus enabling the identification of suspected cases to be tested with CT scans. METHODS: Between April and May 2024, a narrative review was conducted focusing on the differential diagnosis between some rare cases of EVA and otosclerosis. Clinical, audiological, and radiologic features of both conditions were investigated. RESULTS: This review demonstrates the diagnostic challenge in differentiating atypical cases of EVA from otosclerosis in a subset of patients. Clinical and audiological features are important for differential diagnosis, but may not always be sufficient. Therefore, high-resolution computed tomography (HRCT) of the temporal bone plays a pivotal role in definitive diagnosis. CONCLUSIONS: In some specific cases, pre-operative imaging assessment using HRCT emerges as an essential tool for differentiating these two conditions and avoiding unnecessary stapes surgery.

[Advances in vestibular function and rehabilitation of large vestibular aqueduct syndrome].

Large vestibular aqueduct syndrome（LVAS） is a common recessive hereditary hearing loss disease, and some patients may also experience vestibular dysfunction. With the wide application of cochlear implant（CI） and the development of vestibular medicine, the pathophysiological mechanism of LVAS and the influence mechanism of CI on vestibular function are gradually elucidated. Consequently, the evaluation and rehabilitation of vestibular dysfunction function have also become research hotspots. This article reviews studies on vestibular function and related rehabilitation in patients with large vestibular aqueduct syndrome.

Incomplete partition type II in its various manifestations: isolated, in association with EVA, syndromic, and beyond; a multicentre international study.

PURPOSE: Incomplete partition type II (IP-II) is characterized by specific histological features and radiological appearance. It may occur in isolation or in association with an enlarged vestibular aqueduct (EVA). Among those with IP-II and EVA, a subset has a diagnosis of Pendred syndrome. This study aimed to explore the prevalence of isolated IP-II, IP-II with EVA, and cases with a genetic or syndromic basis in our cohort. METHODS: From a large, multicentre database of dysplastic cochleae (446 patients, 892 temporal bones), those with imaging features of IP-II were examined in detail, including whether there was a genetic or syndromic association. RESULTS: A total of 78 patients with IP-II were identified. Among these, 55 patients had bilateral IP-II and EVA (only 12 with typical Mondini triad), 8 with bilateral IP-II and normal VA, 2 with bilateral IP-II and unilateral EVA, and 13 with unilateral IP-II (9 with unilateral EVA). Among the group with bilateral IP-II and bilateral EVA in whom genetic analysis was available, 14 out of 29 (48%) had SLC26A4 mutations and a diagnosis of Pendred syndrome, 1 had a FOXI1 mutation, and a few other genetic abnormalities; none had KCNJ10 pathogenic variants. CONCLUSION: Bilateral IP-II-bilateral EVA may be seen in the context of Pendred syndrome (SLC26A4 or FOXI1 mutations) but, in the majority of our cohort, no genetic abnormalities were found, suggesting the possibility of unknown genetic associations. IP-II in isolation (without EVA) is favored to be genetic when bilateral, although the cause is often unknown.

Variability in Inner Ear Morphology Among a Family With Pendred Syndrome Due to a SLC26A4 Gene Variant.

OBJECTIVES: Pendred syndrome, an autosomal recessive disorder, is often associated with pathogenic variants of the SLC26A4 gene that encodes the pendrin protein. Given its autosomal recessive inheritance, tracing the family history and screening siblings become crucial once a diagnosis of Pendred syndrome is confirmed. This case report aims to underscore the variability in inner ear morphology within a family diagnosed with Pendred syndrome, all carrying the same SLC26A4 gene mutation. METHODS: A chart review and a review of the literature. RESULTS: We present a family of 4, all of whom possess sensorineural hearing loss due to the same homozygous SLC26A4 variant c.919-2A>G. Intriguingly, clinical manifestations, especially inner ear deformities, displayed variability among family members. Notably, 1 family member exhibited a normal cochleovestibular structure morphology, which was rarely reported in the literature. CONCLUSIONS: This report highlights the significance of genetic testing and familial consultation when a proband exhibits typical Pendred syndrome symptoms. It also underscores that the inner ear morphology can exhibit variability among family members, even with the same homozygous SLC26A4 variant.

[Update on diagnostic procedures in third window syndromes. German version]. / Update zur Diagnostik der Drittfenstersyndrome.

BACKGROUND: The diagnosis of third window syndromes often poses a challenge in clinical practice. OBJECTIVE: This paper provides an up-to-date overview of diagnostic procedures in third window syndromes, with special emphasis on superior canal dehiscence syndrome (SCDS), large vestibular aqueduct syndrome (LVAS), and X-chromosomal malformation of the cochlea. MATERIALS AND METHODS: A literature search was performed in PubMed up to December 2023. Furthermore, a selection of the authors' own cases is presented. RESULTS: Audiovestibular tests for the diagnosis of third window syndromes are most often reported for patients with SCDS in the literature. In this context, cut-off values with different sensitivities and specificities have been defined for different outcome parameters of vestibular evoked myogenic potentials. Current developments include the application of electrocochleography, broadband tympanometry, video head impulse testing, and vibration-induced nystagmus. Genetic analyses are increasingly applied in LVAS. CONCLUSION: The diagnosis of third window syndromes is always based on the synthesis of patients' symptoms, clinical signs, audiovestibular test results, and imaging.

Comparison of vestibular aqueduct visualization on computed tomography and magnetic resonance imaging in patients with Ménière's disease.

BACKGROUND: The vestibular aqueduct (VA) serves an essential role in homeostasis of the inner ear and pathogenesis of Ménière's disease (MD). The bony VA can be clearly depicted by high-resolution computed tomography (HRCT), whereas the optimal sequences and parameters for magnetic resonance imaging (MRI) are not yet established. We investigated VA characteristics and potential factors influencing MRI-VA visibility in unilateral MD patients. METHODS: One hundred patients with unilateral MD underwent MRI with three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) sequence and HRCT evaluation. The imaging variables included MRI-VA and CT-VA visibility, CT-VA morphology and CT-peri-VA pneumatization. RESULTS: The most frequent type of MRI-VA and CT-VA visualization was invisible VA and continuous VA, respectively. The MRI-VA visibility was significantly lower than CT-VA visibility. MRI-VA visibility had a weak positive correlation with ipsilateral CT-VA visualization. For the affected side, the MRI-VA visualization was negatively correlated with the incidence of obliterated-shaped CT-VA and positively with that of tubular-shaped CT-VA. MRI-VA visualization was not affected by CT-peri-VA pneumatization. CONCLUSION: In patients with MD, the VA visualization on 3D-SPACE MRI is poorer than that observed on CT and may be affected by its osseous configuration. These findings may provide a basis for further characterization of VA demonstrated by MRI and its clinical significance.

Large Vestibular Aqueduct-Associated Symptoms: Endolymphatic Duct Blockage as a Surgical Treatment.

OBJECTIVE: This study aimed to evaluate the effectiveness of endolymphatic duct blockage (EDB) on dizziness control in patients with a large vestibular aqueduct (LVA) and to evaluate its effect on hearing. STUDY DESIGN: This is a prospective nonrandomized study. SETTING: Five adults and one child with dizziness and five children with progressive hearing loss were referred to our tertiary centers. METHODS: The dizziness handicap inventory (DHI) and DHI-PC (dizziness handicap inventory-patient caregiver) questionnaires were used before and after surgery. All patients underwent a preoperative temporal bone HRCT scan and pure tone audiometry one day before surgery, then four and twelve months after surgery and at the last follow-up. The mean follow-up time was 5.6 years. Student's t-test was used to compare DHI/-PC results. RESULTS: The DHI scores were 44, 24, 84, 59 and 56 before surgery, respectively, for Patients 1 to 5. The DHI scores at four months was significantly different, i.e., 4, 6, 0, 7 and 18 (p = 0.001). No differences were found between 4 and 12 months. Patient 6 (child) had Trisomy 21; their DHI-PC score dropped from 38 (preoperative score) to 8 (postoperative score), showing no activity limitations; clinical evaluation showed the complete resolution of symptoms. We found no significant differences between hearing loss before the surgery and at 1 and 12 months post operation for four adult patients. Our fifth adult patient's hearing changed from severe to profound SNHL. For 5 out of 6 pediatric patients, preoperative PTA and mean ABG were 63 dB and 20 dB, respectively; postoperatively, they improved to 42 dB and 16 dB, respectively. The hearing loss level for the sixth pediatric patient dropped from moderate (PTA = 42 dB) to severe (PTA = 85 dB) due to an opening of the endolymphatic sac and a sudden leak of the endolymph. CONCLUSIONS: EDB, using two titanium clips, seems to be helpful for controlling vestibular symptoms and for stabilizing hearing or even to improve hearing in 82% of cases. Nevertheless, there is a risk of hearing worsening.

[Wideband acoustic immittance characteristics and machine learning-based diagnostic model for children with large vestibular aqueduct syndrome].

Objective:This study was to investigate the wideband acoustic immittance（WAI） characteristics of children with large vestibular aqueduct syndrome（LVAS） and to construct a diagnostic model for LVAS based on WAI and machine learning（ML） techniques. Methods:We performed a retrospective analysis of the data from 38 children（76 ears） with LVAS and 44 children（88 ears） with normal hearing. The data included conventional audiological examination, temporal bone CT scan and WAI test. We performed statistical analysis and developed multivariate diagnostic models based on different ML techniques. Results:The two groups were balanced in terms of ear, gender, and age（P>0.05）. The wideband absorbance（WBA） of the LVAS group was significantly lower than that of the control group at 1 000-2 519 Hz, while the WBA of the LVAS group was significantly higher than that of the control group at 4 000-6 349 Hz（P<0.05）. WBA at 5 039 Hz under ambient pressure had a certain diagnostic value（AUC=0.767）. The multivariate diagnostic model had a high diagnostic value（AUC>0.8）, among which the KNN model performed the best（AUC=0.961）. Conclusion:The WAI characteristics of children with LVAS are significantly different from those of normal children. The diagnostic model based on WAI and ML techniques has high accuracy and reliability, and provides new ideas and methods for intelligent diagnosis of LVAS.

Assessing the optimal MRI descriptors to diagnose Ménière's disease and the added value of analysing the vestibular aqueduct.

OBJECTIVES: To evaluate the diagnostic performance and reliability of MRI descriptors used for the detection of Ménière's disease (MD) on delayed post-gadolinium MRI. To determine which combination of descriptors should be optimally applied and whether analysis of the vestibular aqueduct (VA) contributes to the diagnosis. MATERIALS AND METHODS: This retrospective single centre case-control study evaluated delayed post-gadolinium MRI of patients with Ménièriform symptoms examined consecutively between Dec 2017 and March 2023. Two observers evaluated 17 MRI descriptors of MD and quantified perilymphatic enhancement (PLE) in the cochlea. Definite MD ears according to the 2015 Barany Society criteria were compared to control ears. Cohen's kappa and diagnostic odds ratio (DORs) were calculated for each descriptor. Forward stepwise logistic regression determined which combination of MRI descriptors would best predict MD ears, and the area under the receiver operating characteristic curve for this model was measured. RESULTS: A total of 227 patients (mean age 48.3 ± 14.6, 99 men) with 96 definite MD and 78 control ears were evaluated. The presence of saccular abnormality (absent, as large as or confluent with the utricle) performed best with a DOR of 292.6 (95% confidence interval (CI), 38.305-2235.058). All VA descriptors demonstrated excellent reliability and with DORs of 7.761 (95% CI, 3.517-17.125) to 18.1 (95% CI, 8.445-39.170). Combining these saccular abnormalities with asymmetric cochlear PLE and an incompletely visualised VA correctly classified 90.2% of cases (sensitivity 84.4%, specificity 97.4%, AUC 0.938). CONCLUSION: Either absent, enlarged or confluent saccules are the best predictors of MD. Incomplete visualisation of the VA adds value to the diagnosis. CLINICAL RELEVANCE STATEMENT: A number of different MRI descriptors have been proposed for the diagnosis of Ménière's disease, but by establishing the optimally performing MRI features and highlighting new useful descriptors, there is an opportunity to improve the diagnostic performance of Ménière's disease imaging. KEY POINTS: • A comprehensive range of existing and novel vestibular aqueduct delayed post-gadolinium MRI descriptors were compared for their diagnostic performance in Ménière's disease. • Saccular abnormality (absent, confluent with or larger than the utricle) is a reliable descriptor and is the optimal individual MRI predictor of Ménière's disease. • The presence of this saccule descriptor or asymmetric perilymphatic enhancement and incomplete vestibular aqueduct visualisation will optimise the MRI diagnosis of Ménière's disease.

Enlarged vestibular aqueduct as a cause of postneonatal deafness.

INTRODUCTION: The enlarged vestibular aqueduct (EVA) is the most frequent malformation of the inner ear associated with sensorineural hearing loss (5-15%). It exists when the diameter in imaging tests is greater than 1.5 mm at its midpoint. The association between hearing loss and EVA has been described in a syndromic and non-syndromic manner. It can appear as a familial or isolated form and the audiological profile is highly variable. The gene responsible for sensorineural hearing loss associated with EVA is located in the same region described for Pendred syndrome, where the SCL26A4 gene is located. OBJECTIVE: To describe a series of children diagnosed with EVA in order to study their clinical and audiological characteristics, as well as the associated genetic and vestibular alterations. METHOD: Retrospective study of data collection of children diagnosed with EVA, from April 2014 to February 2023. RESULTS: Of the 17 cases, 12 were male and 5 were female. 5 of them were unilateral and 12 bilateral. In 5 cases, a cranial traumatism triggered the hearing loss. Genetic alterations were detected in 3 cases: 2 mutations in the SCL26A4 gene and 1 mutation in the MCT1 gene. 13 patients (76.5%) were rehabilitated with hearing aids and 9 of them required cochlear implantation. DISCUSSION: The clinical importance of AVD lies in the fact that it is a frequent finding in the context of postneonatal hearing loss. It is convenient to have a high suspicion to diagnose it with imaging tests, to monitor its evolution, and to rehabilitate early.

Association Between Vestibular Aqueduct Morphology and Meniere's Disease.

OBJECTIVE: To investigate the relationship between vestibular aqueduct (VA) morphology and Meniere's disease (MD) using ultrahigh-resolution computed tomography (U-HRCT). METHODS: Retrospective data were collected from 34 patients (40 ears) diagnosed with MD in our hospital who underwent temporal bone U-HRCT with isotropic 0.05-mm resolution, magnetic resonance with gadolinium-enhanced, and pure-tone audiometry; 34 age- and sex-matched controls (68 ears) who underwent U-HRCT were also included. VA patency was qualitatively classified as locally not shown (grade 1), locally faintly shown (grade 2), or clearly shown throughout (grade 3). The width of the outer orifice and VA length and angle were quantitatively measured. Differences in VA morphology between the MD and control groups were analyzed. The correlations between VA morphology and the degrees of hearing loss and endolymphatic hydrops (EH) were also analyzed. RESULTS: VA was classified as grades 1-3 in 11, 17, and 12 ears in the MD group and 5, 26, and 37 ears in the control group, respectively. The patency differed significantly between the groups (p < 0.01). The width of the outer orifice and length of VA were significantly smaller in the MD group than those in the control group (p < 0.05). Both VA patency and length were correlated with the degree of EH in the cochlea and the vestibule (p < 0.05). No difference was found between VA morphology and the degree of hearing loss (p > 0.05). CONCLUSION: The morphological characteristics of VA were found to be associated with the occurrence of MD and the degree of EH. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:3349-3354, 2024.

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.

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.

Characteristics of vestibular-evoked myogenic potentials in children with vestibular malformation and severe sensorineural hearing loss.

BACKGROUND: With the increasing clinical focus on the safety of bilateral cochlear implantation (CI) and the potential risk of bilateral vestibular dysfunction, evaluating vestibular end-organ function in patients with vestibular malformations with accompanying abnormalities has been strongly recommended. OBJECTIVES: To identify the vestibular-evoked myogenic potential (VEMP) values among children with sensorineural hearing loss (SNHL) with vestibular malformation and assess the effectiveness of VEMP testing for inner ear malformations (IEM) diagnosis. METHODS: This study included 96 children (192 ears), including those with vestibular malformations (48 ears), large vestibular aqueduct syndrome (LVAS) (50 ears), and SNHL without IEM (94 ears; control group). All groups underwent ocular and cervical VEMP (oVEMP and cVEMP, respectively) testing. The response rates, VEMP parameters, and wave characteristics were compared. RESULTS: The cVEMP response rates were 37.5 %, 64 %, and 58.51 % and the oVEMP response rates were 42.86 %, 78.95 %, and 77.27 % in the vestibular malformation, LVAS, and control groups, respectively, and significantly differed between groups (cVEMP: X2 = 18.228, P<0.001) (oVEMP: X2 = 7.528, P = 0.023). Significant inter-group differences were observed for the cVEMP and oVEMP latency and amplitude (P < 0.05). The LVAS group's waveform exhibited a prolonged latency and increased amplitude compared with that of the other groups. CONCLUSION: Patients with SNHL were highly susceptible to otolith dysfunction, regardless of comorbid vestibular malformation presence. Measuring VEMPs is an effective and rapid evaluation technique for vestibular function and could provide a basis for vestibular rehabilitation training.

The correlation between deafness progression and SLC26A4 mutations in enlarged vestibular aqueduct patients.

BACKGROUND: The relationship between the hearing phenotype and the SLC26A4 mutation in enlarged vestibular aqueduct cases has not been fully elucidated. OBJECTIVES: To detect SLC26A4 mutation in a group of cases with enlarged vestibular aqueduct who received cochlear implantation and to analyze the correlation between the SLC26A4 genotype and the progression of deafness. MATERIALS AND METHODS: Twenty-nine enlarged vestibular aqueduct patients were selected. Using the Sanger sequence to analyze SLC26A4 gene mutations. The 29 cases were divided into group A (carrying the c.919-2A > G mutation) and group B (not carrying the c.919-2A > G mutation). The difference in the duration of deafness was analyzed between the two groups. RESULTS: The detection rate of the c.1174A > T mutation in the postlingual deafness group was 37.5%, higher than that in the prelingual deafness group (0%). The difference in the duration of deafness between groups A and B was not statistically significant by the Mann-Whitney U test (p > 0.05). CONCLUSIONS: The correlation between the SLC26A4 genotype and the duration of deafness in cases with enlarged vestibular aqueduct is not yet clear. However, the c.1174A > T mutation may be linked to delayed hearing loss and the progression of deafness may be relatively slow in some cases of c.919-2A > G mutation.

[Analysis of 59 cases of large vestibular aqueduct syndrome SLC26A4gene mutation frequency and new mutation sites].

Objective:To study the frequency of SLC26A4 gene mutation sites in children with enlarged vestibular aqueduct deafness in Yunnan, report the new mutation sites of SLC26A4 gene, further clarify the mutation spectrum of SLC26A4gene, and explore the association between biallelic and monoallelic mutations of SLC26A4 gene and CT phenotype of inner ear, so as to provide basis for clinical and genetic diagnosis of deafness. Methods:Review the results of temporal bone CT examination of 390 children after cochlear implantation in the Department of Otolaryngology, Kunming Children's Hospital from August 2016 to September 2021. Sanger sequencing of SLC26A4 gene was performed in 59 children with enlarged vestibular aqueduct. According to the genetic test results, the children who underwent temporal bone CT examination were divided into two groups: SLC26A4 biallelic mutation group（homozygous mutation and compound heterozygous mutation）, monoallelic mutation group, and the association with inner ear CT phenotype was analyzed, and the new sites were summarized and analyzed. Results:The c.919-2a>g mutation was the most common mutation in children with enlarged vestibular aqueduct with SLC26A4 gene mutation. Three new variants of SLC26A4 gene were found; CT examination combined with genetic testing found that a part of children with enlarged vestibular aqueduct was associated with SLC26A4 monoallelic mutation or no SLC26A4 gene mutation was detected. Further research is needed to investigate the involvement of other pathogenic factors in the pathogenesis of EVA.

Non-syndromic enlarged vestibular aqueduct caused by novel compound mutations of the SLC26A4 gene: a case report and literature review.

Enlarged vestibular aqueduct is an autosomal genetic disease mainly caused by mutations in the SLC26A4 gene and includes non-syndromic and syndromic types. This study aimed to identify genetic defects in a Chinese patient with non-syndromic enlarged vestibular aqueduct (NSEVA) and to investigate the impact of variants on the severity of non-syndromic enlarged vestibular aqueduct. A male patient with NSEVA, aged approximately 6 years, was recruited for this study. The clinical characteristics and results of auxiliary examinations, including laboratory and imaging examinations, were collected, and 127 common hereditary deafness genes were detected by chip capture high-throughput sequencing. Protein structure predictions, the potential impact of mutations, and multiple sequence alignments were analyzed in silico. Compound heterozygote mutations c.1523_1528delinsAC (p.Thr508Asnfs*3) and c.422T>C (p.Phe141Ser) in the SLC26A4 gene were identified. The novel frameshift mutation c.1523_1528delinsAC produces a severely truncated pendrin protein, and c.422T>C has been suggested to be a disease-causing mutation. Therefore, this study demonstrates that the novel mutation c.1523_1528delinsAC in compound heterozygosity with c.422T>C in the SLC26A4 gene is likely to be the cause of NSEVA. Cochlear implants are the preferred treatment modality for patients with NSEVA and severe-to-profound sensorineural hearing loss Genetic counseling and prenatal diagnosis are essential for early diagnosis. These findings expand the mutational spectrum of SLC26A4 and improve our understanding of the molecular mechanisms underlying NSEVA.