Background: The inner ear hosts several macrophage populations. Endolymphatic sac macrophages can phagocytose otoconia, and spiral limbus macrophages express genes for fluid shear stress sensing and bone remodeling. Obstruction of endolymph flow by saccular otoconia could be linked to endolymphatic hydrops. Since macrophages are strongly affected by inflammatory status, a role for them in otolith removal could provide a link between inflammation and hydrops. However, the distribution of macrophages around the reuniting duct (RD) and endolymphatic duct (ED), which are narrow structures likely prone to blockage, remains unexplored. Methods: We performed tissue clearing and light-sheet imaging on rat temporal bones. Autofluorescence and immunolabeling for collagen IV, smooth muscle actin, and Iba1 were used to visualize inner ear structures, blood vessels, and macrophages. Results: The connective tissue layer underlying the RD extended from the cochlear spiral limbus. The RD and spiral limbus hosted a continuous microvascular network and macrophage population, comprising both ameboid and ramified cells; macrophages also surrounded the underlying vestibulocochlear artery (VCA). A separate macrophage population, continuous with that of the saccular connective tissue, was found around the endolymphatic sinus and utriculo–endolymphatic (Bast’s) valve; macrophage patterns changed in the vestibular aqueduct and endolymphatic sac. Conclusions: Macrophages are observed in positions consistent with potential roles in sensing luminal changes and in the clearance of obstructive material from the RD and ED; functional confirmation will require targeted experiments.

Endolymph volumes within the cochlea and vestibule differ between Meniere's disease (MD) and similar-age controls. Magnetic resonance imaging (MRI) has potential to diagnose endolymphatic hydrops (EH). In this study, we utilize archival human temporal bones (HTB) to establish objective reference values for endolymph volumes within the cochlea and vestibule in patients with MD and in age-similar controls, for correlation with future MRI studies. Nineteen HTBs were selected for 3-dimensional reconstruction and volume analysis, including 12 HTBs with MD and 7 age-similar control HTBs. HTBs were segmented and volumes of interest were measured allowing for calculation of the vestibular and cochlear endolymphatic ratios (vELR and cELR), representative of the degree of EH within the vestibule and cochlea. Endolymph volumes within the vestibule and cochlea were significantly higher in MD HTBs. There was no difference in volumes of the bony vestibule and cochlea. The vELR and cELR were significantly larger in MD. Control HTB measurements were utilized to establish the upper bound of normal for the vELR and cELR, which were determined to be 33.2% and 8.84%, respectively. Endolymph volumes and the corresponding vELR and cELR values were significantly higher in MD, indicative of EH. Through the ELR, this study provides objective anatomic reference values directly comparable to MRI studies of EH. A threshold for the vELR and cELR is proposed, above which a diagnosis of EH may be warranted.

Visualization of endolymphatic hydrops using MRI has become a cutting-edge method not only for diagnosing Meniere's disease but also for pathophysiological elucidation of the disease. Here, we review recent advances in imaging analysis of the inner ear in Meniere's disease, which could provide additional information over previous findings. In addition to identification of endolymphatic hydrops on MRI, high-intensity signals in the perilymph, which represent alterations in vascular permeability in the blood-perilymph barrier (BPB), might be a key to elucidating the pathophysiology of Meniere's disease. Moreover, high-intensity signals in the endolymphatic duct, which indicate disturbances of the lymph-capillary system, might provide new information for elucidating the pathogenesis of hearing loss and dizziness/vertigo not associated with endolymphatic hydrops. Presence of endolymphatic hydrops is not necessarily the cause of symptoms related to Meniere's disease. Alteration of the BLB might lead to additional disturbances in ears with Meniere's disease and induce clinical symptoms. Disturbances of the lymph-capillary system in endolymphatic duct might induce audio-vestibular symptoms in ears without endolymphatic hydrops. Further development of MRI evaluation of inner ear conditions is desirable not only for accurate diagnosis and elucidation of the pathophysiology of the diseases, but also for early medical intervention to prevent their progression.

To investigate whether the severity of endolymphatic hydrops (EH) influences the audiovestibular effects of intratympanic gentamicin (ITG) in patients with unilateral Ménière disease (uMD). Forty patients in 2 different tertiary referral centers with uMD refractory to medical treatment underwent 3T MRI 4 hours after gadolinium administration. EH severity was evaluated qualitatively and quantitatively (volumetry). Audiovestibular function was assessed with the PTA, vHIT, cVEMP, and oVEMP before and 1 month after ITG. Associations were analyzed with Kruskal-Wallis tests, Pearson/Spearman correlations, and logistic regression models. After ITG, a significant vestibulo-ocular reflex gain reduction was observed in the horizontal (ΔGain: 30.72%) and posterior (ΔGain: 34.64%,) semicircular canals, while hearing showed nonsignificant minimal increase (ΔPTA: 5.88 dB). cVEMP responses were more frequently absent (P = 0.018), and the IAAR increased significantly (P = 0.003). The level of EH and its amount, as measured by the relative volume in the vestibule (vELRaff), both with perilymphatic enhancement, were all positively correlated with the amount of vestibular damage in both PSC and HSC; however, did not correlate with changes in PTA (P = 0.266). In contrast, cochlear EH showed no predictive value for posttreatment hearing loss. Endolymphatic herniation was significantly associated with cVEMP changes (P = 0.016). EH does not act as a barrier to gentamicin diffusion. MRI-based EH assessment may help predict treatment outcomes and guide safer ITG strategies.

3D-FLAIR sequence has an important contribution to the display of endolymphatic hydrops (EH) in Meniere disease (MD), but its clinical application is limited because of the long acquisition time. We investigated whether 3D-FLAIR combined with compressed sensing (CS) technology (3D-FLAIR-CS) can shorten the scan time while maintaining the image quality and diagnostic efficiency for EH. This prospective study included 50 patients with unilateral definite MD who underwent 3T MR imaging 4 hours after gadolinium injection using traditional 3D-FLAIR (10 minutes 35 seconds) and 3D-FLAIR-CS (5 minutes 25 seconds). Image quality was assessed using quantitative (the contrast-to-noise ratio [CNR], SNR, and signal intensity ratio [SIR]) and qualitative methods. The chi-square test compared the diagnostic efficacy of the sequences, paired t tests analyzed quantitative differences, and intra-/interobserver agreement was evaluated using the weighted kappa statistic. Among 50 patients (23 men, 27 women; 27 left ears, 23 right ears), no significant differences were found between the 2 sequences in image quality or diagnosing EH (P >.05). There were no statistically significant differences in CNR (affected side: P = .09; asymptomatic side: P = .07), SNR (affected side: P = .12; asymptomatic side: P = .10), and SIR (affected side: P = .13; asymptomatic side: P = .45) between traditional 3D-FLAIR and 3D-FLAIR-CS, and both sequences exhibited excellent intra- and interobserver agreement (kappa >0.80). Acquisition time for the 3D-FLAIR-CS sequence is reduced by a factor of about 2 compared to traditional 3D-FLAIR, while image quality and diagnostic efficacy in the assessment of EH are the same.

This report presents for the first time a case of triple otic capsule dehiscence (OCD) of the labyrinthine-vascular type, with 2 dehiscences treated simultaneously and effectively by a recently described endovascular approach. Case report. Single otology/neurotology clinic. A 47-year-old male with triple otic capsule dehiscence (OCD) and associated symptoms. Improvement in the Tinnitus Handicap Inventory (THI) and Dizziness Handicap Inventory (DHI) scores. The first OCD was located between the internal jugular vein (IJV) and the posterior semicircular canal (SCC), and the second OCD was located between the vestibular aqueduct (VA) and the IJV. The third OCD, situated between the superior SCC and the superior petrosal sinus, remained untreated since it was considered less contributive to the patient's symptoms. The procedure involved (1) stenting of the right jugular vein combined with (2) coiling of a small portion of the vein in contact with the homonymous vestibular aqueduct. Early clinical signs, along with the audio-vestibular assessment, also suggested the diagnosis of right-sided endolymphatic hydrops. The outcome was uneventful, and the long-term follow-up showed promising results as the menieriform-like vertigo attacks disappeared after the procedure. THI and DHI scores were significantly improved. Auditory symptoms, including tinnitus, also progressively improved, especially after the fitting of a hearing aid. Multiple OCD (not only dehiscence of the superior SCC) should be systematically looked for on high-resolution computed tomography, given that a combined endovascular approach could be carried out in multiple labyrinthine-vascular forms.

Quantitative study of vestibular endolymphatic hydrops in Meniere's disease based on Three-Dimensional real Inversion Recovery (3D-real IR) sequence.

To synthesize current knowledge on the utriculo-endolymphatic valve (UEV, Bast's valve)-a flap-like structure at the junction of the utricular and endolymphatic ducts and to address the central question of whether it represents a passive anatomical remnant or an active regulator of endolymphatic homeostasis with implications for disorders such as Ménière's disease. A critical narrative review of anatomical, imaging, experimental, computational, developmental, comparative, and pathological studies was conducted. Literature was identified through PubMed/MEDLINE, Embase, Web of Science, Scopus, and citation tracking. Sources included human temporal bone reconstructions, animal models, finite element simulations, hydrostatic measurements, and clinical reports examining associations between valve morphology and endolymphatic hydrops. The UEV is consistently identified across species and developmental stages, with asymmetric morphology favoring directional flow. Advanced imaging (micro-CT, SR-PCI) and reconstructions confirm its structural plasticity, while animal and computational models support a check-valve role in modulating endolymph exchange. Pathological observations implicate valve dysfunction in hydrops distribution in MD, though clinical correlations remain inconsistent. No in vivo studies have captured valve dynamics, and interindividual variability remains underexplored. The UEV is an evolutionarily conserved feature of the vestibular labyrinth, likely contributing to inner-ear hydrodynamics. Whether it functions as an active regulator or a passive remnant remains unresolved. Progress will depend on ultra-high-resolution imaging, computational modeling, and prospective clinical studies to clarify its role and potential value for diagnosing and managing hydrops-related disorders.

To analyze the pathophysiological changes in the inner ear in different hearing loss patterns by observing the magnetic resonance imaging (MRI) characteristics of patients with sudden sensorineural hearing loss (SSNHL) and to evaluate the diagnostic value of T1WI/T2WI combined with delayed enhanced intravenous 3D-FLAIR MR technique. In this single-center retrospective study, we performed T1WI, T2WI, and delayed enhanced intravenous 3D-FLAIR MR in 215 patients with SSNHL. Two radiologists independently assessed the MR image. Patients diagnosed with SSNHL were classified into 4 groups according to the audiogram of hearing loss: low-frequency group, flat audiogram group, high-frequency group, and profound deafness group. The MRI findings were classified into inner ear hemorrhage, endolymphatic hydrops (EH), labyrinthitis, or hemorrhagic labyrinthitis, and statistical analysis was performed. A total of 215 cases (99 males/116 females; aged 46.69 ± 15.06) were included. Patients with the T1WI and T2WI scan accounted for 158 cases, patients with delayed enhancement accounted for 176 cases, and those with T1WI, T2WI, and delayed enhancements accounted for 118 cases. The abnormal MRI results' rates in the low-frequency group, flat audiogram group, high-frequency group, and profound deafness group were 25.9%, 33.78%, 24.32%, and 97.82%, respectively. The profound deafness group exhibited significantly higher incidences of inner ear hemorrhage (28.26%), labyrinthitis (45.65%), and hemorrhagic labyrinthitis (23.91%) compared to the low-frequency group (0.00%, 6.90%, 0.00%; P < .001), flat audiogram group (2.70%, 13.51%, 1.35%; P < .001), and high-frequency group (5.41%, 13.51%, 0.00%; P < .001). EH were more prevalent in the low-frequency group (18.97%) and flat audiogram group (16.22%) than in the profound deafness group (0.00%; P = .007). MRI technology can show the pathological change process of the inner ear partially, patients with SSNHL may present with labyrinthitis, hemorrhagic labyrinthitis, EH, hemorrhage of the inner ear, which may be interrelated or mutually transformed, and may be related to the severity and prognosis of the disease.

High-salt intake exacerbates endolymphatic hydrops and alters aldosterone regulation in a Ménière's disease animal model.

Effects of intratympanic administration of glucocorticoids on the guinea pig inner ear.

Degenerative changes in the neurovascular unit (NVU) in the human spiral ganglia (SG) in patients with Meniere's disease (MD) compared with normal patients underlie the clinical manifestations of MD. Endolymphatic hydrops (EH) is the pathologic correlate of MD, yet the etiology of MD is poorly understood. EH alone does not adequately explain the changes in permeability of the cochlear blood-labyrinthine barrier seen with delayed contrast MRI or fluctuations in symptoms. Hematoxylin and eosin sections of the cochlea were obtained from temporal bones of normal patients (n=5, age: 47 to 63y, 1 male/4 female) and patients diagnosed with MD (n=8, age 51 to 88, 4 male/4 female). The number of spiral ganglia neurons (SGNs) in each cochlea was estimated. SGNs and blood vessels in the cochlea from normal and MD patients (archival celloidin sections from the same patients) were reliably identified with antibodies against acetylated-3-tubulin and glucose transporter-1, respectively, and visualized by immunofluorescence and laser confocal microscopy. There was a significant decrease (50% loss) of SGNs among patients diagnosed with MD compared with age-matched controls (P<0.05) and contralateral unaffected cochlea (35% decrease). Immunofluorescence-stained sections showed a marked decrease of blood vessels and a corresponding loss of SGNs in MD cochlea compared with controls. The decrease of spiral ganglia neurons and associated blood vessels showed regional damage of the cochlea. These results suggest that the NVU interaction may be critical to preserve the SGNs in MD and establish a framework for understanding the etiology and treatment of MD beyond EH. Not applicable.

With the increase in the older population, the number of individuals with age-related hearing loss is also growing explosively. Therefore, there is an urgent need to identify the detailed pathology of age-related hearing loss and develop novel treatment strategies. In this study, we have investigated the audiological physiology and cochlear pathology of advanced-age CBA/CaJ mice, a strain that resists early pathological hearing loss. The subjects were naturally aged close to their lifespan limit (> two years) under normal in vivo conditions. We used 11 CBA/CaJ mice aged between 129 and 138 weeks to establish an aged group. To compare the electrophysiological function and histological changes, a young group was established using 12 young mice aged between 9 and 14 weeks. The loss of outer hair cells peaked at 11.3 kHz, and the greatest synapse loss was observed in the 5.6 kHz region, which was covered by the dominant frequency in the ambient sound. Furthermore, atrophy and microthrombus formation occurred in the stria vascularis, with endolymphatic hydrops observed in the cochlear apical turn. In the spiral ganglion and cochlear nerve, a reduction in the number of cells was accompanied by morphological changes indicative of cell aging. Increased levels of derivative-reactive oxygen metabolites, an oxidative stress marker, were observed in aged mice. These results indicate that age-related hearing loss involves a combined pathology of acoustic cochlear damage, which is potentially associated with chronic sound exposure and metabolic changes owing to mitochondrial dysfunction and oxidative stress accumulation. Accordingly, these two distinct etiologies must be addressed to prevent and treat age-related hearing loss.

With the increase in the older population, the number of individuals with age-related hearing loss is also growing explosively. Therefore, there is an urgent need to identify the detailed pathology of age-related hearing loss and develop novel treatment strategies. In this study, we have investigated the audiological physiology and cochlear pathology of advanced-age CBA/CaJ mice, a strain that resists early pathological hearing loss. The subjects were naturally aged close to their lifespan limit (> two years) under normal in vivo conditions. We used 11 CBA/CaJ mice aged between 129 and 138 weeks to establish an aged group. To compare the electrophysiological function and histological changes, a young group was established using 12 young mice aged between 9 and 14 weeks. The loss of outer hair cells peaked at 11.3 kHz, and the greatest synapse loss was observed in the 5.6 kHz region, which was covered by the dominant frequency in the ambient sound. Furthermore, atrophy and microthrombus formation occurred in the stria vascularis, with endolymphatic hydrops observed in the cochlear apical turn. In the spiral ganglion and cochlear nerve, a reduction in the number of cells was accompanied by morphological changes indicative of cell aging. Increased levels of derivative-reactive oxygen metabolites, an oxidative stress marker, were observed in aged mice. These results indicate that age-related hearing loss involves a combined pathology of acoustic cochlear damage, which is potentially associated with chronic sound exposure and metabolic changes owing to mitochondrial dysfunction and oxidative stress accumulation. Accordingly, these two distinct etiologies must be addressed to prevent and treat age-related hearing loss.

ObjectiveThe diagnosis of Ménière's disease (MD) and delayed endolymphatic hydrops (DEH) is challenging due to overlapping symptoms. This study aimed to retrospectively evaluate the diagnostic performance of gadolinium-enhanced delayed inner ear magnetic resonance imaging (MRI) for visualizing endolymphatic hydrops (EH) in patients with MD and DEH.MethodsThis retrospective study included 191 patients with unilateral MD (n = 164) or DEH (n = 27), stratified into definite MD (DMD, n = 129), probable MD (PMD, n = 35), and DEH subgroups. All patients underwent intratympanic administration of gadolinium followed by 3.0-T MRI using 3D-FLAIR and 3D-real-IR sequences. Clinical data, including pure-tone audiometry (PTA), speech recognition score (SRS), electrocochleography (ECochG), and caloric testing, were analyzed to assess correlations between EH and auditory-vestibular function.ResultsEH was detected in 85.2% (23/27) of clinically diagnosed DEH patients. Detection rates were 96.1% in DMD cases and 28.6% in PMD cases. There was no significant difference in cochlear or vestibular EH between the DMD and DEH groups. However, the DMD group exhibited a significantly higher incidence and severity of EH than the PMD group (P < 0.05). In DMD patients, the degree of EH was positively correlated with PTA, clinical stage, and disease course (P < 0.05), and negatively correlated with SRS (P < 0.05). The degree of vestibular EH was also positively correlated with caloric test abnormalities (Spearman's ρ = 0.350, P < 0.001).ConclusionGadolinium-enhanced delayed MRI of the inner ear provides objective evidence of EH and improves the diagnostic accuracy for MD and DEH. Its incorporation into standardized diagnostic protocols may further enhance clinical decision-making.

Optical coherence tomography imaging demonstrates endolymphatic hydrops in the lateral and posterior semicircular canals in noise-exposed mice.

Cross-channel feature transfer 3D U-Net for automatic segmentation of the perilymph and endolymph fluid spaces in hydrops MRI.

Background/Objectives: Skull vibration-induced nystagmus (SVIN) is a rapid bedside test that reveals vestibular asymmetry. Its clinical utility in Ménière’s disease (MD) remains controversial, particularly regarding its association with radiological endolymphatic hydrops (EH). This study aimed to evaluate the relationship between SVIN, audiovestibular parameters, and EH severity in patients with unilateral definite MD. Methods: This prospective observational study was conducted at a tertiary academic referral center and included patients with unilateral MD who underwent SVIN testing (SVT), audiovestibular evaluation (PTA, cVEMP, oVEMP, vHIT, and caloric testing), and 3T MRI with gadolinium-enhanced 3D-FLAIR sequences to quantify EH. Results: In total, 84 patients were included in the study. SVIN was present in 57.14% of patients (n = 48), with ipsilesional nystagmus being the most frequent subtype (64.58%). Patients with SVIN had significantly higher vestibular EH (p = 0.017) and vestibular endolymphatic ratio (REL) in the affected ear (p = 0.019). Disease duration (p = 0.026) and shorter time since last vertigo spell (p = 0.018) were also associated with SVIN presence. REL correlated moderately with disease duration (r = 0.390, p < 0.001), PTA (r = 0.576, p < 0.001), and number of vertigo spells (r = 0.236, p = 0.031), but not with time since last crisis (r = −0.127, p = 0.252). ROC analysis yielded an AUC of 0.735 for REL in predicting SVIN. Conclusions: SVIN correlates with the severity of vestibular EH. This finding indicates a stimulus-locked response of a vestibular asymmetry rather than a purely structural alteration.

Background:To evaluate the clinical outcomes and safety profile of round window reinforcement (RWR) as a minimally invasive surgical treatment for patients with semicircular canal dehiscence syndrome (SCDS).Methods:This retrospective case series analyzed 7 patients (mean age: 59 years) diagnosed with SCDS who underwent transcanal RWR between June 2024 and June 2025 at the Kopfzentrum Bielefeld. Inclusion criteria followed the Bárány Society consensus diagnostic standards. Clinical symptoms, audiometric findings, and vestibular test results—including Dizziness Handicap Inventory (DHI) scores—were assessed pre- and postoperatively. In 2 patients, endolymphatic hydrops was diagnosed via delayed contrast-enhanced magnetic resonance imaging and monitored postoperatively.Results:All patients completed follow-up (mean: 35 months). Improvement in auditory symptoms was observed in 5 of 7 patients (71.4%), including tinnitus relief in 83.3% and hyperacusis relief in 75%. Vertigo improved in 50% of symptomatic cases. No postoperative deterioration in symptoms, DHI score, or hearing was observed. Audiometric outcomes showed a non-significant mean change in air-bone gap (±2.5 dB). No intra- or postoperative complications occurred. In patients with concomitant hydrops, auditory improvement was noted, though vertigo persisted.Conclusion:Round window reinforcement appears to be a safe and effective therapeutic option for selected patients with SCDS, particularly those presenting predominantly auditory symptoms or contraindications to more invasive procedures. Further prospective studies are needed to validate these findings and define the role of RWR in the broader surgical management of third window syndromes.

Clinical doses of gadodiamide have no damaging effects on cochlear tissue in vitro and in vivo.