Endolymphatic Duct Research Articles

Otolithiasis in the Animal Kingdom: A Retrospective Analysis.

If otolithiasis can be demonstrated to affect multiple species, it may be possible to identify an experimental animal for prospective study of this entity. Otolithiasis refers to dislodged otolithic matter within the confines of the membranous labyrinth that has the potential to cause clinical symptoms. The mechanism involves separation of free-floating otoconia that can affect the hearing and balance functions of the ear. While this process is known to occur in humans, it is uncertain if other species are affected. The published images of 37 whole-mount specimens of mammalian labyrinths were identified for retrospective examination. These were evaluated stereographically for the presence of calcareous material in abnormal locations within the membranous labyrinth. Thirty normal labyrinth specimens were found, exemplified by that of the Cape sea lion. Seven pathologic specimens were found, including a human, a black ape, a yellow-faced baboon, a hocheur monkey, a collie dog, a common sheep, and a common hare. Abnormal accumulations of calcareous material were found at one or more sites, more frequently in the utricle and canal system and less frequently in the endolymphatic and cochlea ducts. Otolithiasis appears to occur in other animal species besides the human. Abnormal calcareous material was found in various locations within the membranous labyrinth of affected animals. One or more of these might serve as an animal model to prospectively study the phenomenon of otolithiasis.

A Three-Year Follow-Up of a Patient With Large Vestibular Aqueduct Syndrome Who Underwent Bilateral Endolymphatic Duct Blockage Surgery

A Three-Year Follow-Up of a Patient With Large Vestibular Aqueduct Syndrome Who Underwent Bilateral Endolymphatic Duct Blockage Surgery

Correlation of Endolysmphatic Duct Signal Intensity With Clinical Features in Otological Diseases.

Bilateral high signal intensity (SI) in the endolymphatic duct (ED) on magnetic resonance imaging (MRI) has been reported as a common characteristic in ears with large vestibular aqueduct syndrome (LVAS). However, the significance of bilateral high SI in the ED remains unknown. The present study aimed to compare the correlation between SI in the ED and the clinical manifestations in various otological disorders and consider the significance of the MRI findings. Retrospective study. University hospital. The study included 2,450 ears from 1,225 patients with various otological disorders. All ears underwent 3T enhanced MRI and were evaluated for the degree of endolymphatic hydrops (EH) and the SI ratios (SIRs; i.e., the calculation between SIs in the ED and those in the cerebellum). The imaging findings were compared with their clinical symptoms. Ears with bilateral high SIRs in the ED tended to have considerably less occurrence of EH in both the cochlea and vestibule than those with bilateral low SIRs. Ears with SIR ≥8 showed significantly elevated hearing thresholds at lower frequencies on pure-tone audiometry, although they exhibited a markedly lower incidence of cochlear EH than those with SIR <8. Moreover, ears with vertigo exhibited notably higher SIRs than those without vertigo. Bilateral high SI in the ED on MRI may reflect pathophysiology underlying sensorineural hearing loss and vestibular symptoms, which are not associated with EH formation.

Efficacy of endolymphatic duct blockage in treating Ménière's disease.

Ménière's disease (MD) is an idiopathic inner ear disorder characterized by recurrent episodes of episodic rotational vertigo, fluctuating hearing loss, tinnitus, and a feeling of ear stuffiness. Endolymphatic sac (ES)-related surgery is used primarily in patients with MD who have failed to respond to pharmacologic therapy. Endolymphatic duct blockage (EDB) is a new procedure for the treatment of MD, and related clinical studies are still scarce. This study aims to investigate the dynamic changes in endolymphatic hydrops (EH) and the long-term surgical outcomes in MD patients undergoing EDB, and to evaluate the impact of different types of ES on the surgical efficacy. A retrospective analysis was conducted on 33 patients with refractory MD who underwent EDB. Based on the morphology of their endolymphatic sacs, patients were divided into a normal-type group (n=14) and an atrophic-type group (n=19). The frequency of vertigo symptoms, hearing, vestibular function, and the dynamic changes of gadolinium-enhanced MRI of the inner ear were compared were compared before and after surgery between the 2 groups. Compared with the atrophic-type group, the patients in the normal-type group had a higher rate of complete vertigo control, better cochlear and vestibular function, and a lower endolymph to vestibule volume ratio (all P<0.05). In addition, 7 patients in the normal-type group were found to have reversal of EH, while no reversal of EH was detected in the atrophic-type group after surgery. The response to EDB treatment varies between normal and atrophic MD patients, suggesting that the 2 pathological types of endolymphatic sacs may have different underlying mechanisms of disease.

Endolymphatic duct blockage surgery vs. intratympanic steroids for treatment of refractory Ménière's disease.

To compare the effectiveness of the Endolymphatic duct blockage (EDB) and intratympanic methylprednisolone(ITMP) injection to control refractory Ménière's disease(MD) symptoms and evaluate their impact on hearing level. Retrospective study in a tertiary care center. 36 received ITMP injection and 52 EDB. Mean outcome measures at 24months included vertigo control, tinnitus, aural fullness and hearing level: pure-tone average (PTA), bone conduction average(BCA) and speech discrimination score(SDS). At 24months postoperatively, 90.4% of the EDB group had complete control of vertigo and 43.4% of the ITMP group (p = 0.001). There was no significant difference in tinnitus or aural fullness control (p = 0.34 and p 0.21 respectively). In each group, the drop in tinnitus and aural fullness frequency at 24months were significant for EDB (p = 0.03; p < 0.001 respectively) and for ITMP group in tinnitus (p = 0.03) but not aural fullness (p = 0.063). At 24months, PTA, BCA and SDS were significantly worst in the ITMP group when compared to preoperative levels (p = 0.038, p = 0.027, p = 0.016). PTA in the EDB group was stable with no difference compared to ITMP group (p = 0.48). BCA and SDS in the EDB group were stable and better than the ITMP group (p = 0.032; p = 0.036). In each group, vestibular paresis was not significantly different before (p = 0.06) and after treatment (p = 0.68). EDB is more effective than the ITMP for controlling the vertigo symptoms of Ménière's disease and in preserving hearing function. It is a novel surgical technique with promising results for a complete treatment of Ménière's disease. ITMP decreases the frequency and the severity of the symptoms but only control vertigo in 27.8% of cases.

A New Methodology for Evaluation of Large Vestibular Aqueduct in CT and MRI Images.

Development of a new method for large vestibular aqueduct (LVA)/large endolymphatic sac anomaly (LESA) assessment using magnetic resonance imaging (MRI) and computed tomography (CT)/cone beam CT (CBCT) images. The secondary objective was to compare both modalities. The gold standard for LVA diagnosis is the analysis of CT images using Valvassori and Clemis or Cincinnati criteria. The previous studies showed inconclusive results regarding the correlation between audiological and radiological data. Retrospective analysis of radiological images from 173 patients (315 ears), who were diagnosed with LVA/LESA based on CT/CBCT and/or MRI images of the temporal bone. The images obtained using both techniques were used to measure the following dimensions of vestibular aqueduct (VA)/endolymphatic duct (ED)/intraosseous endolymphatic sac (ES): width of the opening, length, and width at external aperture. In MRI images, the maximal contact diameters of the extraosseous or intraosseous ES and dura mater were measured as well. LVA has been reported to be bilateral in 82% (142 patients) and unilateral in 18% (31 patients) of cases. Comparison of MRI and CT/CBCT measurements showed a moderate correlation (0.64) in external aperture, a moderate correlation (0.57) in the width of the VA opening, and a weak correlation (0.34) in length measurements (p < 0.05). We developed a new method to identify the heterogeneous pathology of LVA/LESA using reconstruction along the VA/ED/intraosseous ES axis, three measurements on two planes, and focus on the maximal contact diameter between the extraosseous or intraosseous ES and dura mater.

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

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. This is a prospective nonrandomized study. Five adults and one child with dizziness and five children with progressive hearing loss were referred to our tertiary centers. 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. 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. 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.

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

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

A rare clinical case of a labyrinthine lesion: an endolymphatic sac tumor

Endolymphatic sac tumors are rare neoplasms originating from the endolymphatic epithelium of the intraosseous part of the endolymphatic duct and sac, typically characterized by slow growth and local destructive changes. We present a case of an endolymphatic sac tumor in a 28-year-old man who consulted an otoneurologist with complaints of progressive hearing loss and dizziness attacks and was referred for a CT scan of the temporal bones and MRI of the inner ear with delayed contrast enhancement. The data of otoneurological and radiological examinations before and after surgical treatment and the results of surgical treatment with histological verification of the tumor are presented. The objective of this case presentation is to demonstrate the usefulness of CT and MRI methods in detecting an endolymphatic sac tumor, to compare the results of otoneurological and radiological examinations and intraoperative and histological data followed by surgery. Radiological examination revealed a neoplasm of the right temporal bone with typical imaging characteristics of endolymphatic sac tumor. Surgery was performed, the mass was removed completely, and the endolymphatic sac tumor was histologically verified. Radiologic presentation includes a typically located area of bone destruction in the petrous part of the temporal bone in the area of the vestibular aqueduct, possibly with the spread of the tumor into the cerebellopontine angle, with a heterogeneous structure, with uneven contrast enhancement. Due to the rarity of this pathology, diagnosis in the early stages is often difficult, and for the correct interpretation of radiologic findings in patients with hearing loss and dizziness, knowledge of the normal anatomy of the temporal bone and awareness of rare variants of its lesions are of key importance. Timely examination of patients with suspected temporal bone lesions and correct diagnosis are the key to successful treatment and maintaining the quality of life in this group of patients.

Endolymphatic Duct and Sac Decompression: A New Life for an Old Technique.

Ménière's disease is an inner ear disorder causing recurrent vertigo, hearing loss, and tinnitus. Diagnosis is based on the variability of the symptoms over time and absence of radiological abnormalities. Medical therapy is effective only in a small percentage of patients. Surgical strategies remain controversial. In this article, we revisit a surgical technique neglected over the years: endolymphatic sac surgery. Fifty-four patients affected by Ménière's disease underwent endolymphatic duct and sac decompression. According to the American Academy of Otolaryngology-Head and Neck Surgery criteria, vertigo control was evaluated with follow-up at 6 months, 1 year, and 2 years from the intervention. Hearing results were evaluated before the surgery and at 2 years of follow-up using the pure tone average. The results were compared with similar techniques of endolymphatic sac surgery described in the literature. According to the American Academy of Otolaryngology-Head and Neck Surgery criteria classification, 2 years after surgery, 87% patients achieved complete control of vertigo (class A). The hearing remained stable in 93.5% of patients. The results appear compatible with other publications data regarding endolymphatic sac surgeries. The duct and endolymphatic sac decompression allows the control of vertigo and preserves hearing from the pathological effects of Ménière's disease. The revised technique allows the functional restoration of endolymphatic homeostasis.

An expanding mechanical role for the tiny mammalian endolymphatic duct: 2. An explanation for the beaching of whales–failure of osmotic pressure counterbalancing mechanism in the cochlea causing acute vertigo attack

Endolymphatic Hydrops (EH) describes a swelling of the endolymphatic duct (ED). It is a key correlate of human Ménière’s disease featuring incapacitating giddy attacks. Direct measurements by micropuncture to be presented support the hypothesis that swelling occurs because water flows through aquaporins into the ED under an osmotic gradient to stabilize basilar membrane position against deep dive pressures. Patients having vestibular attacks often display nystagmus if not also perilymphatic fistulae or dehiscences. As shown by Ketten et al. (2004), stranded whales also exhibit nystagmus and also intracochlear bleeding. Here, EH is modelled as a normal rate-limited osmotic mechanism which likely evolved to cope with synoptic variation. It has been extensively adapted by beaked whales to allow diving to feed on squid at great depths—where they still need to hear. Their more-robust EDs normally cope with very slow equalization against megapascal pressures. An unexpected undersea pressure transient may trigger perilymph-endolymph membrane rupture and consequent vertigo attack, well documented in humans. Due to acoustic spread, whole pods may be variously affected. Humans need to remain stationary while waiting hours for their attack to subside. Marine mammals with limited oxygen stores may panic and surface too quickly, accounting for life-threatening decompression sickness.

An expanding mechanical role for the tiny mammalian endolymphatic duct: 1. Modification of Békésy model is specifically needed to cope with ambient pressure variation—with weather, altitude or ocean depth

von Békésy’s pioneering work and two-chamber model with basilar membrane (BM) separating the perilymph chambers was a first-pass assumption which worked to explain basic frequency-band analysis. Yet it did not cover psychoacoustical phenomena. Nor did it cover the repeated demonstrations by this author of baseline displacements of the BM, nor mysterious changes in the volume of the tiny endolymphatic duct—even in human ears with normal thresholds. Since 2009 the duct has been shown to possess all the necessary characteristics of a pressure vessel, viz., it is lined with aquaporins and tight junctions while the cells of the stria vascularis maintain a strict osmotic gradient. We submit that such evolutionary change was necessary because ambient pressure changes are too large to be corrected by passive equalization and need to be actively eliminated to preserve hearing sensitivity. Any theory must cover marine mammals which have adapted to ocean pressures measured in megapascals. In this case, infrasound is modelled as a varying pressure pedestal which must be cancelled. This video presentation covers one possible mechanical configuration for how such a cancelation might be achieved—a hypothesized feedback control system utilizing outer hair cell somatic motility plus our previously-modelled otolith-based pressure transducer.

CHD7 variants associated with hearing loss and enlargement of the vestibular aqueduct

Enlargement of the endolymphatic sac, duct, and vestibular aqueduct (EVA) is the most common inner ear malformation identified in patients with sensorineural hearing loss. EVA is associated with pathogenic variants in SLC26A4. However, in European–Caucasian populations, about 50% of patients with EVA carry no pathogenic alleles of SLC26A4. We tested for the presence of variants in CHD7, a gene known to be associated with CHARGE syndrome, Kallmann syndrome, and hypogonadotropic hypogonadism, in a cohort of 34 families with EVA subjects without pathogenic alleles of SLC26A4. In two families, NM_017780.4: c.3553A > G [p.(Met1185Val)] and c.5390G > C [p.(Gly1797Ala)] were detected as monoallelic CHD7 variants in patients with EVA. At least one subject from each family had additional signs or potential signs of CHARGE syndrome but did not meet diagnostic criteria for CHARGE. In silico modeling of these two missense substitutions predicted detrimental effects upon CHD7 protein structure. Consistent with a role of CHD7 in this tissue, Chd7 transcript and protein were detected in all epithelial cells of the endolymphatic duct and sac of the developing mouse inner ear. These results suggest that some CHD7 variants can cause nonsyndromic hearing loss and EVA. CHD7 should be included in DNA sequence analyses to detect pathogenic variants in EVA patients. Chd7 expression and mutant phenotype data in mice suggest that CHD7 contributes to the formation or function of the endolymphatic sac and duct.

Visualization and clinical relevance of the endolymphatic duct and sac in Ménière's disease.

Ménière's disease (MD) is a chronic inner ear disorder with a multifactorial etiology. Decreased visualization of the endolymphatic duct (ED) and sac (ES) is thought to be associated with MD, although controversy exists about whether this finding is specific to MD. Recent literature has revealed that two distinct ES pathologies, developmental hypoplasia and epithelial degeneration, can be distinguished in MD using the angular trajectory of the vestibular aqueduct (ATVA) or ED-ES system as a radiographic surrogate marker. It has been suggested that these two subtypes are associated with distinct phenotypical features. However, the clinical differences between the ATVA subtypes require further validation. The objective of this study is to investigate whether (1) non-visualization of the ED-ES system is a discriminative radiological feature for MD in a cohort of vertigo-associated pathologies (VAPs) and whether (2) different angular trajectories of the ED-ES system in MD are associated with distinguishable clinical features. The study was conducted in the Vertigo Referral Center (Haga Teaching Hospital, The Hague, the Netherlands). We retrospectively assessed 301 patients (187 definite MD and 114 other VAPs) that underwent 4h-delayed 3D FLAIR MRI. We evaluated (1) the visibility of the ED-ES system between MD and other VAP patients and (2) measured the angular trajectory of the ED-ES system. MD patients were stratified based on the angular measurements into αexit ≤ 120° (MD-120), αexit 120°-140° (MD-intermediate), or αexit ≥ 140° (MD-140). Correlations between ATVA subgroups and clinical parameters were evaluated. Non-visualization of the ED-ES system was more common in definite MD patients compared with other VAPs (P < 0.001). Among definite MD patients, the MD-140 subtype demonstrated a longer history of vertigo (P = 0.006), a higher prevalence of bilateral clinical disease (P = 0.005), and a trend toward a male preponderance (p = 0.053). No significant differences were found between ATVA subgroups regarding the presence or severity of auditory symptoms, or the frequency of vertigo attacks. Non-visualization of the ED-ES system is significantly associated with MD. Among MD patients with a visible ED-ES system, we demonstrated that the MD-140 subtype is associated with a longer disease duration, a higher prevalence of bilateral MD, and a trend toward a male preponderance.

Quantitative assessment of inner ear variation in elasmobranchs.

Considerable diversity has been documented in most sensory systems of elasmobranchs (sharks, rays, and skates); however, relatively little is known about morphological variation in the auditory system of these fishes. Using magnetic resonance imaging (MRI), the inner ear structures of 26 elasmobranchs were assessed in situ. The inner ear end organs (saccule, lagena, utricle, andmacula neglecta), semi-circular canals (horizontal, anterior, and posterior), and endolymphatic duct were compared using phylogenetically-informed, multivariate analyses. Inner ear variation can be characterised by three primary axes that are influenced by diet and habitat, where piscivorous elasmobranchs have larger inner ears compared to non-piscivorous species, and reef-associated species have larger inner ears than oceanic species. Importantly, this variation may reflect differences in auditory specialisation that could be tied to the functional requirements and environmental soundscapes of different species.

Hearing Outcomes Following Endolymphatic Duct Blockage Surgery and Factors Associated with Improved Audition at Two Years Follow-Up.

Objective: To evaluate hearing outcomes at 2 years post endolymphatic duct blockage (EDB) surgery, with an analysis of factors that may predict hearing improvement. Study Design: Retrospective comparative study. Setting: Tertiary care center. Subjects: Definite Ménière's Disease (MD) patients undergoing EDB for refractory disease. Methods: Chart review was conducted to assign cases to one of the three hearing outcome groups (deteriorated, stable, and improved). All cases that met our inclusion criteria were selected. Preoperative data collected were audiograms, bithermal caloric tests, preoperative vertigo episodes, history of previous ear surgery for Ménière, intratympanic steroid injections (ITS) and intraoperative endolymphatic sac (ELS) tear or opening. Postoperative data collected at 24 months were audiograms, vertigo episodes and bithermal caloric testing. Results: Preoperative vertigo episodes, caloric paresis and history of surgery, ITS injections or ELS integrity, as well as postoperative vertigo class distribution and caloric paresis changes were not different between our groups. Preoperative word recognition score (WRS) was lowest in the improved hearing group (p = 0.032). The persistence of tinnitus at 2 years postoperatively was associated with deteriorated hearing (p = 0.033). Conclusions: There are no strong predictors of hearing improvement on presentation pre-EDB, but low preoperative WRS may be the best estimator available. Therefore, ablative interventions should be considered very carefully in patients presenting with low WRS, as they may benefit more from EDB; there is a fair chance of a good hearing outcome with EDB surgery. Persistence of tinnitus can reflect deteriorating audition. Vertigo control and hearing preservation are independent outcomes of EDB surgery, making it desirable as an early intervention for refractory MD cases.

What a Neurosurgeon Should Know About the Endolymphatic Sac: Part 3 – Ménière Disease

Abstract Objective To elucidate all the aspects that neurosurgeons should know about the Ménière disease (MD). Methods Review of guidelines, books, and studies from 1933 to 2021, from basic to translational research, using human and animal endolymphatic sac (ES) tissue or cells, as well as reviews, case reports, and papers about surgical experience. This article is divided into three parts. In this last part, we review the MD. Results The MD is one of the most common pathologies in the ES. It was first described by Prosper Ménière in 1861 with its clinical triad: dizziness, tinnitus, and hearing loss. A lot of theories relating ES to the MD have been proposed. Some of them postulate that it is caused by a narrowing and shortening in the endolymphatic duct, and others relate it to severe inflammation on the ES. Mostly due to the lack of understanding of this pathology, the diagnosis is mainly clinical, despite histopathology being helpful to confirm the diagnosis. The treatment of the MD can be done in 3 different ways: pharmacological, nonpharmacological, and surgical. Conclusion The MD is one of the most common pathologies in the inner ear and has been largely studied over the years. The latest diagnosis guidelines must help in the classification and give better basis for diagnosis and treatment, which, despite not being curative yet, has improved over the years. Pharmacological treatment based on the possible etiologies, allied with proper diet and routine exercise, is showing promising results.

What a Neurosurgeon Should Know About the Endolymphatic Sac: Part 2 – Diagnosis and Management of the Endolymphatic Sac Tumors

Abstract Objective This article is divided into three parts. In the second part of this review, the authors focus on describing the endolymphatic sac tumor and presenting illustrative cases. Methods A review of previous studies, from 1957 to 2021, from basic and translational research using human and animal endolymphatic sac (ES) tissue or cells, as well as other reviews on this theme. Results The ES is an inner ear structure, which is responsible for the homeostatic regulation, as well as endolymphatic fluid volume control, immune response etc. One of the possible alterations of the ES is the ELST, a low-grade malign neoplasm that originates from the epithelium of the endolymphatic duct and sac. The clinical presentation of the ELST includes hearing loss, tinnitus, headache, and vertigo. The diagnosis in the early stages is rare, given that this group of symptoms is very similar to other, more common, diseases such as the Meniere syndrome. Its diagnosis is made by computed tomography (CT), magnetic resonance imaging (MRI), immunohistochemistry, and confirmed by histopathology. However, none of these examinations are part of the pathological guidelines for ELST. The treatment for ELST in the early stages has a high rate of success. Conclusion The ELST is a very difficult diagnosis due to its presentation. Furthermore, the interactions between ELST and the Von Hippel-Lindau disease usually result in a more aggressive condition. Despite the difficulty of the diagnosis, doing it early increases the chances of successful treatment.

Can MRI biomarkers for hearing loss in enlarged vestibular aqueduct be measured reproducibly?

Morphological features of an enlarged endolymphatic duct (ED) and sac (ES) are imaging biomarkers for genotype and hearing loss phenotype. We determine which biomarkers can be measured in a reproducible manner, facilitating further clinical prediction studies in enlarged vestibular aqueduct hearing loss. A rater reproducibility study. Three consultant radiologists independently measured previously reported MRI ED & ES biomarkers (ED midpoint width, maximal ED diameter closest to the vestibule, ES length, ES width and presence of ES signal heterogeneity) and presence of incomplete partition Type 2 from 80 ears (T2 weighted axial MRI). Interclass correlation coefficients (ICC) and Gwet's Agreement Coefficients (AC) were generated to give a measure of reproducibility for both continuous and categorical feature measures respectively. ES length, width and sac signal heterogeneity showed adequate reproducibility (ICC 95% confidence intervals 0.77-0.95, Gwet's AC for sac heterogeneity 0.64). When determining ED midpoint width, measurements from multiple raters are required for "good" reliability (ICC 95% CI 0.75-0.89). Agreement on the presence of incomplete partition Type 2 ranged from "moderate" to "substantial". Regarding MR imaging, the opinion of multiple expert raters should be sought when determining the presence of an enlarged ED defined by midpoint width. ED midpoint, ES length, width and signal heterogeneity have adequate reproducibility to be further explored as clinical predictors for audiological phenotype. We report which ED & ES biomarkers are reproducibly measured. Researchers can confidently utilise these specific biomarkers when modelling progressive hearing loss associated with enlarged vestibular aqueduct.

Endolymphatic Duct Blockage as a Surgical Treatment Option for M&amp;#233;ni&amp;#232;re's Disease

Endolymphatic duct blockage is a relatively new treatment option for Ménière's disease, aiming to reduce vertigo attacks while sparing hearing and equilibrium. After a regular mastoidectomy, the posterior semicircular canal is identified, and Donaldson's line is determined. This is a line through the horizontal semicircular canal, crossing the posterior semicircular canal. The endolymphatic sac is usually found at this site under the posterior semicircular canal. The bone of the endolymphatic sac and the dura are thinned until the sac is skeletonized, after which the endolymphatic duct is identified. The duct is then blocked with a titanium clip. Using a computerized tomography (CT) scan, the position is confirmed. Follow-up visits take place 1 week, 6 weeks and 1 year after surgery. To this day, only one prospective trial assessing this method has been conducted, comparing this new method to endolymphatic sac decompression. Results of the duct blockage are promising, with 96.5% of the patients free of vertigo after 2 years. However, further research is required.