Imaging and clinical findings in large endolymphatic duct and sac syndrome

Does CISS MRI Reliably Depict the Endolymphatic Duct in Children with and without Vestibular Aqueduct Enlargement?

BACKGROUND AND PURPOSE

High-resolution CT is the mainstay for diagnosing an enlarged vestibular aqueduct (EVA), but MR imaging may be an appealing alternative, given its lack of ionizing radiation exposure. The purpose of this study was to determine how reliably MR imaging demonstrates the endolymphatic duct and endolymphatic duct enlargement in hearing-impaired children.

MATERIALS AND METHODS

We performed a retrospective review of temporal bone high-resolution CT and MR imaging of hearing-impaired children evaluated between 2017 and 2020. Vestibular aqueduct diameter was measured on high-resolution CT. The vestibular aqueducts were categorized as being enlarged (EVA+) or nonenlarged (EVA-) using the Cincinnati criteria. The endolymphatic ducts were assessed on axial high-resolution CISS MR imaging. We categorized endolymphatic duct visibility into the following: type 1 (not visible), type 2 (faintly visible), and type 3 (easily visible). Mixed-effect logistic regression was used to identify associations between endolymphatic duct visibility and EVA. Interreader agreement for the endolymphatic duct among 3 independent readers was assessed using the Fleiss κ statistic.

RESULTS

In 196 ears from 98 children, endolymphatic duct visibility on MR imaging was type 1 in 74.0%, type 2 in 14.8%, and type 3 in 11.2%; 20.4% of ears were EVA+ on high-resolution CT. There was a significant association between EVA+ status and endolymphatic duct visibility (P < .01). Endolymphatic duct visibility was type 1 in 87.1%, type 2 in 12.8%, and type 3 in 0% of EVA- ears and type 1 in 22.5%, type 2 in 22.5%, and type 3 in 55.0% of EVA+ ears. The predicted probability of a type 3 endolymphatic duct being EVA+ was 0.997. There was almost perfect agreement among the 3 readers for distinguishing type 3 from type 1 or 2 endolymphatic ducts.

CONCLUSIONS

CISS MR imaging substantially underdiagnoses EVA; however, when a type 3 endolymphatic duct is evident, there is a >99% likelihood of an EVA.

A Long-Term Follow-Up Study on the Auditory Performance and Speech Intelligibility of Mandarin-Speaking Prelingually Deaf Children With Isolated Large Vestibular Aqueduct Syndrome After Cochlear Implantation

PURPOSE

The purpose of this study was to evaluate the auditory performance and speech perception of 104 children with isolated large vestibular aqueduct syndrome (LVAS) and 523 children with no inner ear malformation (IEM) for 5 years after cochlear implantation, in order to explore whether isolated LVAS can affect the long-term hearing and speech rehabilitation of deaf children after cochlear implantation.

METHOD

A cohort study was established consisting of 627 children who underwent cochlear implantation at Beijing Tongren Hospital from 1999 to 2016. The children were examined at 0, 6, 12, 24, 36, 48, and 60 months after cochlear implantation to assess their auditory performance and speech perception using the Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) questionnaires.

RESULTS

The CAP scores of the isolated LVAS group increased significantly during the baseline to the 24th month, after which they gradually rose until reaching the plateau during the 24th to the 60th month. The CAP scores of the non-IEM group increased significantly during the baseline to the 36th month and then increased steadily. The SIR scores went up significantly during the baseline to the 48th month, and increased in a gradual manner in other stages of isolated LVAS evaluation. In comparison, The SIR scores of non-IEM group grew remarkably from the baseline to the 60th month. There were no significant differences in the CAP or SIR scores between isolated LVAS and non-IEM groups in each stage of evaluation, with the only exception being the CAP score at baseline month after cochlear implantation.

CONCLUSIONS

The CAP and SIR questionnaires are helpful tools for quantifying the early hearing and speech skills of younger prelingually deafened cochlear implant recipients. This long-term follow-up study shows that the speech and hearing development of children in isolated LVAS and non-IEM groups follow similar patterns, and isolated LVAS does not affect the long-term rehabilitation of deaf children after cochlear implantation.

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.

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.

The Diagnostic Efficacy of MRI in the Evaluation of the Enlarged Vestibular Aqueduct in Children with Hearing Loss

Objective

The aim of our study is to evaluate the diagnostic effectiveness of magnetic resonance imaging (MRI) compared to computed tomography (CT) in the detection of enlarged vestibular aqueduct (EVA) in childhood.

Methods

One hundred twenty-three children who underwent temporal bone CT and MRI examinations for hearing loss between 2013 and 2020 were evaluated retrospectively. All CT and MRI images were examined by two pediatric radiologists, according to the Valvassori and Cincinnati criteria for EVA. Imaging findings on CT and MRI of the vestibular aqueduct were recorded. Two pediatric radiologists performed the measurements for EVA on CT and MRI. In addition, an otolaryngologist performed the measurements independently. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI compared to CT were calculated to detect EVA. The difference between the measurements on CT and MRI was investigated. The inter-observer agreement was evaluated for measurements.

Results

The mean age of 123 children (65 boys and 58 girls) was 50.18±50.40 months. Two hundred forty-six ears were evaluated in 123 children. On CT images, EVA was present in 28 (11.3%) of 246 ears according to Cincinnati criteria and 27 (10.9%) of 246 ears according to Valvassori criteria, respectively. While sensitivity, specificity, PPD, and NPD rates of MRI were 100%, 99%, 92.8%, and 100%, respectively, for Cincinnati criteria, for Valvassori criteria, they were 100%, 97.3%, 77.7%, and 100%, respectively. According to the visual evaluation performed without using measurement, the enlarged appearance of the vestibular aqueduct was significant for the diagnosis of EVA (p<0.001), while the absence of this appearance was significant for the exclusion of EVA (p<0.001). There was no significant difference between the measurements on CT and MRI. There was a perfect correlation between the observers for measurements.

Conclusion

MRI can be used as an initial imaging technique in children with suspicion of EVA to reduce radiation exposure.

The biomechanical characteristics of human vestibular aqueduct: a numerical-based model construction and simulation

Vestibular aqueduct is a precise structure embedded in the temporal bone and plays a key role in the physiological function of inner ear by maintaining the endolymphatic circulation and buffering the impact from intracranial pressure. Although the alterations on the morphology or volume of vestibular aqueduct result in variety of diseases, the approaches of evaluating the condition of vestibular aqueduct are still unsatisfing because the pathological sections utilized for the 3D construction model most likely undergoes morphological changes. In this study, the vestibular aqueduct images obtained by CT scanning were processed by finite element method to construct the 3D model. To assess if this numerical model reflects the actual biomechanical properties of vestibular aqueduct, the fluid-solid coupling calculation was applied to simulate the endolymphatic flow in the vestibular aqueduct. By measuring the dynamics of endolymphatic flow, and the pressure and displacement on round membrane under external pressure, we found the numerical 3D model recapitulated the biomechanical characteristics of the real vestibular aqueduct. In summary, our approach of 3D model construction for vestibular aqueduct will provide a powerful method for the research of vestibular aqueduct-related diseases.

Speech development after cochlear implantation in infants with isolated large vestibular aqueduct syndrome

Background: Few studies on speech performance of children after cochlear implantation (CI) described isolated large vestibular aqueduct syndrome (LVAS). Objective: To investigate speech developmental trajectories of infants with LVAS after CI, and to compare with those who have structurally normal inner ears. Materials and methods: 1112 infants with congenital severe to profound hearing loss participated in this study. 150 infants in group A were diagnosed with LVAS, 962 infants in group B with structurally normal inner ear. The speech performance was assessed via the Meaningful Use of Speech Scale (MUSS). The evaluations were performed pre-implant, 1, 3, 6, 9, 12, 24, 36, 48 and 60 months after CI. Results: The mean scores of the MUSS improved over a 5-year period after implantation in both groups A and B. The LVAS group presented similar speech developmental trajectory to the non-LVAS group at each assessment interval, except pre-operation. There were significant differences in mean scores between vocalizing behavior and oral communication skills, clarification skills of infants in both two groups. Conclusions and significance: Speech performance of infants with LVAS developed rapidly after CI and was similar to infants with structurally normal inner ear. For infants with isolated LVAS, CI had a significant effect and should be recommended as a therapeutic option.

The Natural History of Labyrinthine Hemorrhage in Patients With Sudden Sensorineural Hearing Loss

To investigate the application of inner ear 3-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) in patients with sudden sensorineural hearing loss (SSNHL) accompanied by inner ear hemorrhage. A total of 1252 SSNHL patients who were admitted from January 2010 to April 2018 were included in the study. The patients' clinical features, complete blood counts, coagulation profiles, audiometry data, and MRI scans were retrospectively reviewed. Twenty-four patients had high labyrinth signals on inner ear 3D-FLAIR MRI (24/1252, 1.9%) that were diagnosed as inner ear hemorrhage. One patient had endolymphatic hydrops on the contralesional side. In the 24 patients, pure tone audiometry curves revealed profound deafness (19/24) and flat moderate hearing loss (5/24); most patients had associated vertigo (23/24) and tinnitus (19/24). Patients with SSNHL (N = 24) were treated. Sixteen patients had invalid improvement, 3 patients were markedly improved, 4 patients had effective treatment, and only 1 patient was cured, for a therapeutic efficacy of 33.3% (8/24). Follow-up 3D-FLAIR MRI in patients showed absorbance of labyrinthine hemorrhage and disappearance of the high signal intensity in the inner ear within 2 weeks to 4 months. Inner ear 3D-FLAIR MRI indicate that most cases of inner ear hemorrhage are spontaneous and that high labyrinth signals are absorbed within 4 months. The site of labyrinth hemorrhage is irregular and independent of hearing loss. Conventional treatment is not very effective, and an appropriate therapy for SSNHL requires further investigation.

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.

Variability of vestibular aqueduct measurements among axial, single-oblique and double-oblique computed tomography images

OBJECTIVE

To investigate the morphology and dimensions of the vestibular aqueduct on axial, single-oblique and double-oblique computed tomography images.

METHODS

The computed tomography temporal bone scans of 112 patients were retrospectively evaluated. Midpoint and opercular measurements were performed using axial, single-oblique and double-oblique images. Morphometric analyses were also conducted. The vestibular aqueduct sizes on axial, single-oblique and double-oblique images were compared.

RESULTS

At the midpoint, the mean (± standard deviation) vestibular aqueduct measured 0.61 ± 0.23 mm, 0.74 ± 0.27 mm and 0.82 ± 0.38 mm on axial, single-oblique and double-oblique images, respectively; at the operculum, the vestibular aqueduct measured 0.91 ± 0.30 mm, 1.11 ± 0.45 mm and 1.66 ± 1.07 mm on the respective images. The co-efficients of variation of the vestibular aqueduct measured at the midpoint were 37.4 per cent, 36.5 per cent and 47.5 per cent on axial, single-oblique and double-oblique images, respectively; at the operculum, the measurements were 33.0 per cent, 40.5 per cent and 64.5 per cent. Regarding morphology, the vestibular aqueduct was fissured (33.5 per cent), tubular (64.3 per cent) or invisible (2.2 per cent).

CONCLUSION

The morphology and dimensions of the vestibular aqueduct were highly variable among axial, single-oblique and double-oblique images.

Diagnostics and therapy of sudden hearing loss

This article reviews recent aspects of diagnostics, differential diagnostics, and evidence in systemic and local therapy of idiopathic sudden sensorineural hearing loss (ISSHL). Since a number of disorders can be accompanied by sudden hearing loss, a meaningful and targeted diagnostic strategy is of utmost importance. An important differential diagnosis of sudden hearing loss are intralabyrinthine schwannomas (ILS). The incidence of ILS is probably significantly underestimated. This may be due to the lack of awareness or lack of explicit search for an intralabyrinthine tumor on MRI or an inappropriate MRI technique for the evaluation of sudden hearing loss ("head MRI" instead of "temporal bone MRI" with too high slice thicknesses). Therefore, the request to the radiologist should specifically include the question for (or exclusion of) an ILS. With special MRI techniques, it is possibly today to visualize an endolymphatic hydrops. The evidence in the therapy of ISSHL is - with respect to the quality and not quantity of studies - unsatisfying. The value of systemically (low dose) or intratympanically applied corticosteroids in the primary treatment of ISSHL is still unclear. In order to investigate the efficacy and safety of high dose corticosteroids as primary therapy for ISSHL, a national, multicenter, three-armed, randomized, triple-blind controlled clinical trial is currently performed in Germany (http://hodokort-studie.hno.org/). After insufficient recovery of the threshold with systemic therapy of ISSHL, intratympanic corticosteroid therapy appears to be associated with a significantly higher chance of an improved hearing threshold than no therapy or placebo. Both, hearing gain and final hearing threshold, however, appear to be independent from the onset of secondary therapy. Based on currently available data from clinical studies, no recommendation can be made with respect to the type of corticosteroid and specifics of the intratympanic application protocol.

Enlarged vestibular aqueduct: Audiological and genetical features in children and adolescents

BACKGROUND

Enlarged Vestibular Aqueduct (EVA) is one of the most common congenital malformations associated with sensorineural or mixed hearing loss. The association between hearing loss and EVA is described in syndromic (i.e. Pendred Syndrome, BOR, Waardenburg) and non-syndromic disorders, as isolate or familiar mutations of the SLC26A4 gene. The audiological phenotype of the EVA syndrome is heterogeneous, the type and entity of hearing loss may vary and vertigo episodes might also be present.

OBJECTIVE

The aim of this retrospective study was to describe the clinical and genetic features of a group of adolescent subjects presenting an EVA clinical profile, considering the presence of SLC26A4 gene mutations.

METHODS

14 Caucasian patients were assessed (24 ears in total; 4 patients presented a monolateral EVA), 10 females and 4 males. Their age at the time of diagnosis was between 1 and 6 years (mean age 2.5 years). Subjects were assessed by an ENT microscopy evaluation with a complete audiometric assessment, CT & MRI scans and genetic tests for the evaluation of the pendrin gene mutations (SLC26A4).

RESULTS

Considering the presence of SLC26A4 mutations and thyroid function, we could identify three sub-groups of patients: group 1, non syndromic EVA (ns EVA, no SLC26A4 mutation and no thyroid dysfunction); group 2, EVA with DFNB4 (single SLC26A4 gene mutation and no thyroid dysfunction); group 3, EVA with Pendred Syndrome (two pathological mutation of SLC26A4 and thyromegaly with thyroid dysfunction). Patients of group 1 (ns-EVA) showed various degrees of hearing loss from mild (55%) to severe-profound (45%). In groups 2 (DFNB4) and 3 (PDS), the degree of hearing loss is severe to profound in 70-75% of the cases; middle and high frequencies are mainly involved.

CONCLUSIONS

The phenotypic expressions associated with the EVA clinical profile are heterogeneous. From the available data, it was not possible to identify a representative audiological profile, in any of the three sub-groups. The data suggest that: (i) a later onset of hearing loss is usually related to EVA, in absence of SLC26A4 gene mutations; and (ii) hearing loss is more severe in patients with SLC26A4 gene mutations (groups 2 and 3 of this study).

Relationship between multidetector CT imaging of the vestibular aqueduct and inner ear pathologies

This study investigated the relationships between morphological changes in the vestibular aqueduct (VA) in different inner ear pathologies. Eighty-eight patients (34 males and 54 females, ranging from seven to 88 years of age; average age 49.2 years) with cochleovestibular disorders underwent temporal bone CT (with a 64-channel helical CT system according to temporal bone protocol parameters; 0.6 mm slice thickness, 0.6 mm collimation, bone reconstruction algorithm). All patients with cochleovestibular disorders who underwent temporal bone CT had been previously divided into six different suspected clinical classes: A) suspected pathology of the third window; B) suspected retrocochlear hearing loss; C) defined Ménière's disease; D) labyrinth lithiasis; E) recurrent vertigo. On CT images we analyzed the length, width and morphology of the VA, contact between the VA and the jugular bulb (JB), the thickness of the osseous capsule covering the semicircular canals, the pneumatization rate of the temporal bone and the diameter of the internal auditory canal. At the end of the diagnostic work-up all patients were grouped into six pathological classes, represented as follow: 1) benign paroxysmal positional vertigo (BPPV), 2) recurrent vertigo (RV), 3) enlarged vestibular aqueduct syndrome (EVAS), 4) sudden or progressive unilateral sensorineural hearing loss (SNHL), 5) superior semicircular canal dehiscence syndrome (SSCD), 6) recurrent vestibulocochlear symptoms in Ménière's disease. We evaluated 176 temporal bones in 88 patients. The VA was clearly visualized in 166/176 temporal bones; in ten ears the VA was not visualized. In 14 ears (11 patients, in three of whom bilaterally) we found an enlarged VA while in 31 ears the VA was significantly narrower. In 16 ears a dehiscence of the JB with the vestibular or cochlear aqueduct was noted. In all six patients with suspected EVAS we found a AV wider than 1.5 mm on CT scans; moreover CT identified four patients with large VA and ill-defined clinical symptoms. Most patients with BPPV (11 patients, Class 1) we did not find any VA abnormalities on CT scans, confirming the clinical diagnosis in ten patients; in the remaining patients we found an enlarged VA, not clinically suspected. In the RV class (eight patients, Class 2) we found three patients with negative CT scans, two patients with narrow aqueduct and subsequently reclassified as Ménière's disease patients, and three patients with ectasic JB dehiscence with the VA. In patients suffering from SNHL we found no statistically significant correlation with the morphological abnormalities. The clinical suspicion of SSCD was confirmed by CT in 11/13 patients (84.6 %); in addition another seven patients showed a thinning or dehiscence of the superior semicircular canals as the prevailing alteration on CT scans, and were reclassified in this group. Ménière's disease symptoms were correlated with a VA alteration in more than half of the cases; the most striking finding in this class was that the VA was significantly narrower (21 patients). Our study demonstrates that alterations of the VA morphology are not only related to EVAS but are also found in other inner ear pathologies such as Ménière's disease. Furthermore, MDCT may confirm the presence of correlations between the morphology of inner ear structures such as VA, semicircular canals or JB dehiscence, and alterations of vestibulocochlear function.

Magnetic resonance imaging features of large endolymphatic sac compartments: audiological and clinical correlates

OBJECTIVES

(1) To study the prevalence and characteristics of large endolymphatic sac internal compartments on thin-section T2- and T2*-weighted magnetic resonance imaging, and to relate these to other large endolymphatic sac magnetic resonance imaging features, and (2) to correlate the compartment imaging features, endolymphatic sac size and labyrinthine anomalies with the patients' clinical and audiological data.

METHOD

Magnetic resonance imaging studies for 38 patients with large endolymphatic sac anomalies were retrospectively reviewed in a tertiary referral centre. Endolymphatic sac compartment presence, morphology and imaging signal were assessed. Endolymphatic sac size and labyrinthine anomalies were also recorded. Endolymphatic sac compartments and other imaging features were correlated with clinical and audiological data.

RESULTS

Compartments were present in 57 per cent of the imaged endolymphatic sacs, but their presence alone did not correlate with other imaging features or clinical data. The endolymphatic sac : internal auditory meatus signal ratio was associated with a history of sudden or fluctuating hearing loss. Hearing loss correlated with opercular and extraosseous endolymphatic sac size measurements. A larger midpoint intraosseous endolymphatic sac size was associated with clear fluid loss at cochlear implantation.

CONCLUSION

The magnetic resonance imaging characteristics of large endolymphatic sac compartments have been defined. The endolymphatic sac size and distal compartment signal should be recorded, as these provide prognostic information and assist the planning of appropriate interventions.

Coronal CT scan measurements and hearing evolution in enlarged vestibular aqueduct syndrome

OBJECTIVE

To assess the correlation between the enlarged vestibular aqueduct (EVA) diameter and (1) the hearing loss level (mild, moderate, severe and profound and (2) the hearing evolution. The secondary objective was to obtain measurement limits on the coronal plane of the temporal bone CT scan for the diagnosis of EVA.

METHODS

Retrospective study in a tertiary pediatric center. Mastoid CT scans were reviewed to measure the VA diameter at its midpoint and operculum on axial and coronal planes in a pathologic and normal population. We used their serial audiograms to assess the evolution of hearing.

RESULTS

101 EVA was identified out of 1812 temporal bones CT scan from our radiologic database in 8 years. Bone conduction was stable after a mean follow-up of 40.9 ± 32.9 months. PTA has been the most affected in time by the EVA (p=0.006). No correlation was identified between impedancemetry and the diameter of the EVA. On the diagnostic audiogram, 61% of hearing loss were in the mild and moderate hearing levels; at the end of the follow-up 64% of hearing loss are still in the mild and moderate hearing levels. The cut-off values for the coronal midpoint and operculum planes on the CT scan to diagnose an EVA are 2.4 mm and 4.34 mm respectively.

CONCLUSIONS

Conductive or mixed hearing loss might be the first manifestation of EVA. Coronal CT scan cuts can provide additional information to evaluate EVA especially when axial cuts are not conclusive.

Albumin-like protein is the major protein constituent of luminal fluid in the human endolymphatic sac

The endolymphatic sac (ES) is an inner ear organ that is connected to the cochleo-vestibular system through the endolymphatic duct. The luminal fluid of the ES contains a much higher concentration of proteins than any other compartment of the inner ear. This high protein concentration likely contributes to inner ear fluid volume regulation by creating an osmotic gradient between the ES lumen and the interstitial fluid. We characterized the protein profile of the ES luminal fluid of patients (n = 11) with enlarged vestibular aqueducts (EVA) by proteomics. In addition, we investigated differences in the protein profiles between patients with recent hearing deterioration and patients without hearing deterioration. The mean total protein concentration of the luminal fluid was 554.7±94.6 mg/dl. A total of 58 out of 517 spots detected by 2-DE were analyzed by MALDI-TOF MS. The protein profile of the luminal fluid was different from the profile of plasma. Proteins identified from 29 of the spots were also present in the MARC-filtered human plasma; however, the proteins identified from the other 25 spots were not detected in the MARC-filtered human plasma. The most abundant protein in the luminal fluid was albumin-like proteins, but most of them were not detected in MARC-filtered human plasma. The concentration of albumin-like proteins was higher in samples from patients without recent hearing deterioration than in patients with recent hearing deterioration. Consequently, the protein of ES luminal fluid is likely to be originated from both the plasma and the inner ear and considering that inner ear fluid volumes increase abnormally in patients with EVA following recent hearing deterioration, it is tempting to speculate that albumin-like proteins may be involved in the regulation of inner ear fluid volume through creation of an osmotic gradient during pathological conditions such as endolymphatic hydrops.

Superior semicircular canal dehiscence and enlarged vestibular aqueduct

Superior semicircular canal dehiscence is a well described labyrinthine defect, detect in pediatric population too. We report a case of superior semicircular canal dehiscence, which radiological diagnosis was confirmed by multiplanar reformatted CT images, associated to omolateral enlarged vestibular aqueduct in a 16-year-old female who presented with congenital hearing loss without vestibular symptoms. Both inner ear malformations act as a third mobile window into the labyrinth and cochleo-vestibular symptoms can result from loud sounds or pressure changes. An early diagnosis should be strived for preserve inner ear functions.

Genetic syndromes involving hearing

OBJECTIVE

The fundamental processes involved in the mechanism of hearing seem to be controlled by hundreds of genes and hereditary hearing impairment may be caused by a large variety of genetic mutations in different genes. Approximately 150 loci for monogenic syndromic and non-syndromic hearing impairment (HI) disorders have been mapped to the human genome. The identification of these genes and functional analysis of the proteins they encode, are paving the way towards a better understanding of the physiology and pathophysiology of the auditory system. To date, approximately 50 causative genes have been identified.

METHODS

The clinical and neuroradioldical findings of syndromal hearing impairment are analysed.

RESULTS

This paper presents an updated report on genetic syndromes in which a hearing impairment is involved, with a particular attention to the ones associated with external ear and craniofacial malformations.

CONCLUSIONS

Concepts in human genetics are rapidly evolving together with technologies. The concept itself of gene is changing. A genetic diagnosis of syndromal hearing impairment has many practical consequences: it can implies specific prognosis, specific management, specific recurrence risk in relatives and, if the diagnosis is confirmed at the molecular level, possibility of a specific early prenatal diagnosis for severe syndromes. It is important to highlight the necessity that the pediatric otolaryngologist must have a close collaboration with a clinical geneticist and a neuroradiologist.

Cochlear abnormalities associated with enlarged vestibular aqueduct anomaly

OBJECTIVES

The objective of this study is to examine the correlation between enlarged vestibular aqueduct (EVA) anomaly and other inner ear anomalies such as cochlear dysplasia, vestibulocochlear dysplasia and modiolar hypoplasia.

METHODS

Retrospective chart review, with institutional review board approval, of patients with EVA who received treatment at Primary Children's Medical Center or University Hospital at the University of Utah, between 1997 and 2006. Review of radiographs was done to evaluate for the presence of EVA and other inner ear anomalies.

RESULTS

Twenty patients (40 ears) were included in the study, 17 patients had bilateral EVA and three patients had unilateral EVA. There were 10 females and 10 males. The average age of all patients at the time of initial diagnosis was 1.7 years (0-6 years). Thirty-seven ears were shown to have EVA (92.5%). Of those ears with EVA, 29 (78.4%) had one or more inner ear anomalies. Twenty-three (62.2%) ears had cochlear dysplasia, six (16.2%) had vestibulocochlear dysplasia, and 18 (48.7%) had modiolar hypoplasia.

CONCLUSIONS

Using small field of view, thin section CT and/or MR imaging, cochleovestibular abnormalities are commonly identified in association with EVA.

Computed tomography findings in large vestibular aqueduct syndrome

CONCLUSIONS

Patients with large vestibular aqueduct syndrome (LVAS) have disturbed morphogenesis of bony labyrinth. Semicircular canal anomalies are common in LVAS.

OBJECTIVE

To describe the additional inner ear anomalies on CT imaging in pediatric patients with LVAS, and to investigate the lateral semicircular canal (LSCC) anomalies associated with LVAS by measurement of the LSCC bony island width.

PATIENTS AND METHODS

We retrospectively reviewed the digitally stored temporal bone CT imaging obtained for 23 patients with LVAS, additional inner ear anomalies were noted, and measurements of the LSCC bony island width were made on axial CT scans on the workstation. Measurements were compared to the normative data obtained from 20 patients without sensorineural hearing loss.

RESULTS

Of the 23 patients (bilateral in 22 and unilateral in 1), additional inner ear malformations were identified in 21 cases presenting either singly or in combination. A small LSCC bony island (<3 mm in diameter) appeared highly typical; vestibule and LSCC anomalies were identified in 13 cases (26 ears) based on visual inspection combined with abnormal measurements. Dehiscence of the superior and/or posterior semicircular canal was identified in 19 ears, and Mondini deformity was identified in 6 ears.

Recurrent bacterial meningitis after cochlear implantation in a patient with a newly described labyrinthine malformation

Authors report on a so far undescribed bilateral inner ear malformation with congenital deafness where a defect of both the medial and lateral bony labyrinthine wall allowed the herniation of a cerebrospinal fluid-filled endosteum sac into the tympanic cavity. The story of cochlear implantation in this ear and the series of following meningitis demonstrates the dilemma of indicating implantation in labyrinthine dysplasia and the difficulties of treating postimplantation meningitis. Routes of bacterial invasion from inner ear to intracranium is discussed regarding normal, dysplastic and surgically "disturbed" inner ear anatomy.

Ménière disease: diagnostic instrumental support

The current guidelines of the American Academy of Otolaryngology-Head and Neck Surgery entrust the diagnosis of Ménière disease (MD) only to the clinical presentation and the pure tone audiometry. However, most otolaryngologists request a widened instrumental evaluation of the patients suspected of MD. The effective reliability of the further instrumental support for the diagnosis of MD is still debated in the literature because of nonstandardized procedures and sometimes incoherence among authors. New and more sophisticated diagnostic tests have been developed both in audiovestibology and in imaging in the last few years. A review of the recent literature on this controversial subject is provided.

[Large endolymphatic duct and sac syndrome (LEDS) : part I: analysis of imaging findings]

OBJECTIVE

Large endolymphatic duct and sac (LEDS) syndrome is the most common radiologically detectable form of inner ear malformation (IEM) associated with sensorineural hearing loss (SNHL). Nevertheless, it is relatively unknown in the German-speaking countries.

METHODS

Among all patients referred from ear, nose, and throat specialists to the radiology department with clinically suspected IEM between 1994 and 2003, we identified the cases of LEDS. The retrospective study included clinical records, high-resolution computed tomography, and magnetic resonance imaging.

RESULTS

Of 169 patients, 17 (median age 12 years; 12 females) showed LEDS. A total of 28 ears were affected. Ten patients (6%; 15 ears) had isolated LEDS, while seven patients showed additional IEM (4%; 13 ears). The most frequent of these was dysplastic vestibule (13/13 ears), followed by Mondini deformity (10/13 ears) and dilated semicircular canals (7/13 ears). Three of 13 ears revealed severe IEM of the cochlea, vestibule, and semicircular canals. No correlation could be demonstrated between the severity of morphological changes and the degree of SNHL.

CONCLUSION

LEDS may be an underestimated cause of SNHL. Imaging is necessary for a confident diagnosis.

[Large endolymphatic duct and sac syndrome : part 2: clinical manifestations]

OBJECTIVE

The aim of this study was to clarify the clinical course of large endolymphatic duct and sac syndrome (LEDS). Although LEDS is the most common form of radiologically detectable inner ear malformation associated with sensorineural hearing loss (SNHL), it is relatively unknown in the German-speaking countries. We hoped to derive useful pointers for clinical care.

METHODS

We evaluated the clinical audiometric records and imaging findings of 169 patients with clinically suspected inner ear malformation seen between 1994 and 2003. Following identification of all LEDS cases, we serially investigated the anamnestic and functional data with regard to severity and course.

RESULTS

Among 169 patients, 17 (median age 12 years; 12 females) showed LEDS. A total of 28 ears were affected. Clinically, most cases were of prelingual or perilingual onset and displayed steady or fluctuatingly progressive severe SNHL with emphasis on the high frequencies or deafness. Episodes of sudden hearing loss were relatively frequent. No correlation could be demonstrated between the severity of morphological changes and the degree of SNHL.

CONCLUSION

Progression of SNHL and episodes of sudden hearing loss were seen mainly in late childhood or adolescence. This should be taken into account when informing and advising patients and planning therapy.

When is the vestibular aqueduct enlarged? A statistical analysis of the normative distribution of vestibular aqueduct size

BACKGROUND AND PURPOSE

The size of vestibular aqueducts (VAs) seen on CT studies varies. The current practice of calling a VA enlarged when it exceeds a certain threshold (eg, 1.5 mm at the midpoint) is arbitrary. Our hypothesis was that statistical analysis of the range of VA widths in a normal-hearing population would lead to a mathematic definition of the upper-limit-of-normal VA width.

MATERIALS AND METHODS

The VA midpoint and opercular widths were measured in 73 children with normal hearing. Statistical analysis yielded values of the 99 th, 97.5th, 95th, 90th, 75th, and 50th percentiles for this normal distribution.

RESULTS

The upper-limit-of-normal (95th percentile) values for the VA midpoint and opercular widths were 0.9 and 1.9 mm, respectively. The VAs with greater widths may reasonably be considered enlarged.

CONCLUSION

The VAs with midpoint or opercular widths of 1.0 and 2.0 mm or greater, respectively, are enlarged.

Preoperative integrated imaging in paediatric cochlear implantation

Sensorineural hearing loss affects one to two children out of 1000 born apparently healthy and 9% approximately of those born with the risk of different pathologies. The origin of premature deafness is unknown in 25% of children whereas it is genetic in some cases. Prevention and early diagnosis, possibly within six to eight months, aim to avoid deafness becoming a cause of disability. The aim of the present study was to establish the optimal preoperative assessment with a diagnostic imaging protocol involving the integrated use of CT and MRI in the selection of the candidates for cochlear implantation. Twenty children were assessed, divided into three different groups: A) those who had CT only; B) those who had only MR; C) those who had both CT and MRI. The purpose was to estimate diagnostic accuracy in preoperative planning and the role of imaging in the diagnostic protocol for children's deafness. The petrous pyramid was studied with a CT Picker PQ 6000 system to high resolution in the axial and coronal planes, and with an MR Intera Philips 0.5 T device by means of acquisition of sequences B-TFE T2 3D and MIP reconstructions on radial coronal plans. This study was completed successfully for morphological brain MRI examination to complete the diagnosis. The following abnormalities were found in six patients (30%): one case of incomplete partition (Mondini malformation); two cases of vestibular aqueduct enlargement; two cases with anomalous jugular bulb positioning; one case with cochlear ossification. In the remaining 70%: eight patients had no anatomical anomalies; CT and MRI imaging were normal in six patients with minor abnormalities disclosed at surgery (one case of the stapedial artery emerging from the promontory); three anatomical variants of the round window, and two abnormal course of the facial nerve). We emphasize the importance of integrated CT and MRI imaging in the study of children with sensorineural hearing loss. The combination of CT and MRI has been shown to be superior to either modality used alone in view of "risk-free" cochear implantation. High resolution computed tomography and magnetic resonance images obtained by B-TFE T2-weighted 3D sequences help the surgeon in planning the operation and predict operative difficulty and potential complications in paediatric cochlear implant candidates.