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Background Neuro-otological factors that influence changes in spontaneous nystagmus (SN) during vertigo attacks in Ménière’s disease (MD) remain unclear . Objective To identify neuro-otological factors that might influence the initial direction of SN and the directional change of SN. Methods A prospective, observational study of 22 patients with definite MD to evaluate the initial direction and directional change of SN during vertigo attacks, endolymphatic hydrops (EH) volume, and the function of horizontal semicircular canal and hearing levels. Results SN consistently began as irritative in 17 of 22 cases, and 9 of 17 cases showed a definite change in direction after onset. SN consistently began as paralytic in 5 of 22 cases, and 3 of 5 cases showed a definite change in direction after onset. Subjects in the irritative initial SN group had less severe degrees of hearing loss, smaller cochlear and vestibular EH volume than the paralytic initial SN group ( P  = 0.017, < 0.001, and 0.009, respectively). Subjects in the SN direction change group had significantly smaller maximum slow phase velocity, percentage of caloric weakness and canal paresis than the no SN direction change group ( P  = 0.001, 0.006, and 0.001, respectively). Simple logistic regression analysis showed that smaller EH volume was significantly associated with initial irritative SN (OR = 0.867, 95% CI 0.762–0.988, P  = 0.032) and that the degree of canal paresis was negatively associated with the presence of directional change of SN (OR = 0.022, 95% CI 0.002–0.289, P  = 0.004). Conclusions The morphology of EH and canal paresis may independently affect the characteristics of SN in patients with MD.

Lack of proven biomarkers for hearing instability (HI) disorders leads to difficulty and delays in diagnosis. Given the association of HI with endolymphatic hydrops (EH), imaging-based techniques for quantification of endolymph and perilymph may be useful for improved clinical management. This study longitudinally characterizes variations in endolymph fluid volume and correlations with hearing changes. This prospective cohort study (2021–2024) followed 14 patients (age 29–73) meeting criteria for HI over 15 months and 12 healthy volunteers (age 22–75). Contrast Enhanced Delayed (CED)-MRI using 3D FLAIR and STIR sequences was performed every 3–6 months, under a deep phenotyping protocol including standard hearing threshold testing. Perilymph and endolymph volumes were quantified using a semi-automatic MRI processing and analysis pipeline. Individual endolymph-to-perilymph (E/P) ratio variance over time was higher in ears with fluctuating hearing and MRI-designated EH (Mann-Whitney U Test: U  = 39, 27; p  = 0.01, 0.003 respectively). On linear regression, increasing vestibule E/P ratio correlated with worse hearing ( Estimate  = 45.31, SE =  7.88, p  < 0.001) and visit-to-visit change in E/P ratio increased with shifts to worse hearing thresholds ( Estimate  = 141.84, SE  = 45.69, p  = 0.003). Longitudinal assessment of HI patient imaging therefore allows detection of quantifiable fluctuations in EH that correlate with hearing changes. This methodology could improve monitoring of HI and evaluation of potential therapies. Trial registration number: NCT04806282.

Objective To investigate the clinical characteristics and endolymphatic hydrops (ELH) Manifestations in patients with delayed Ménière’s disease (DMD) compared to classic Ménière’s disease (CMD). Methods A prospective cohort study was conducted involving 523 patients diagnosed with MD. Clinical data, inner ear function, and ELH characteristics were analyzed and compared between CMD and DMD groups. Assessments included audiometry, VEMP, and MRI. Results DMD prevalence was 6.1%. Bilateral MD was significantly more common in DMD (34.4% vs. 14.5%, P  = 0.003). DMD patients had more severe hearing loss in the first involved ear and more deteriorated VEMP in the contralateral ear ( P  < 0.05). ELH was present in 100% of affected ears, with a higher contralateral ELH proportion in DMD (34.4% vs. 15.0%, P  = 0.005). Conclusions DMD patients exhibit a higher prevalence of bilateral MD, more severe hearing loss, and greater contralateral ELH compared to CMD patients. Both subtypes share similar ELH characteristics, suggesting common underlying mechanisms.

The symptoms of Meniere’s disease (MD) are generally considered to be related to endolymphatic hydrops (EH). There are many recent reports supporting the possibility that vasopressin (VP) is closely linked to the formation of EH in Meniere’s disease. Based on this, we developed a clinically relevant animal model of Meniere’s disease in which a VP type 2 receptor agonist was administered after electrocauterization of the endolymphatic sac. We report live imaging of the internal structure, and functional changes of the inner ear after electrocauterization of the endolymphatic sac and administration of a VP type 2 receptor agonist. In this model, the development of EH was visualized in vivo using optical coherence tomography, there was no rupture of Reissner’s membrane, and low-tone hearing loss and vertiginous attacks were observed. This study suggested that acute attacks are caused by the abrupt development of EH. This is the first report of live imaging of the development of EH induced by the administration of a VP type 2 receptor agonist.

Traumatic noise causes hearing loss by damaging sensory hair cells and their auditory synapses. There are no treatments. Here, we investigated mice exposed to a blast wave approximating a roadside bomb. In vivo cochlear imaging revealed an increase in the volume of endolymph, the fluid within scala media, termed endolymphatic hydrops. Endolymphatic hydrops, hair cell loss, and cochlear synaptopathy were initiated by trauma to the mechanosensitive hair cell stereocilia and were K⁺-dependent. Increasing the osmolality of the adjacent perilymph treated endolymphatic hydrops and prevented synaptopathy, but did not prevent hair cell loss. Conversely, inducing endolymphatic hydrops in control mice by lowering perilymph osmolality caused cochlear synaptopathy that was glutamate-dependent, but did not cause hair cell loss. Thus, endolymphatic hydrops is a surrogate marker for synaptic bouton swelling after hair cells release excitotoxic levels of glutamate. Because osmotic stabilization prevents neural damage, it is a potential treatment to reduce hearing loss after noise exposure.

Purpose Diagnosis of Menière’s disease relies on clinical symptoms. Injected 3T MRI can show endolymphatic hydrops (EH), but correlation with the clinical status of MD, (probable -PMD or definite-DMD) remains doubtful. We revealed endolymphatic pressure disruption through functional exploration and verified if it was associated with an EH through MRI. Materials and methods We prospectively analyzed 3D3T FLAIR MRI of DMD and PMD patients. All of them underwent electrocochleography (EcoG), distortion-product otoacoustic emissions (DPOAEs), and videonystagmograhy (VNG). Amplitudes of summating potential (SP) and cochlear nerve action potential (AP) were measured on EcoG. DPOAE-phase was collected at 1 kHz for the 2f1-f2 DPOAE between sitting and laying position. A SP/AP ≥ 40% and a DPOAE phase-shift > 40° revealed pressure disruption. Results 39 patients (25 women, 53 y.o. 20–78), were included, with 32 DMD ears and 11 PMD ears. MRI was performed in a median of 21 days [0; 68] from the MD incident. Audiovestibular exploration took place 41 days after the crisis [0;83]. MRI revealed an EH in 71.9% and 27.2% of DMD and PMD, respectively. When combining functional explorations and MRI, testing was positive in 97% for DMD and 82% for PMD. When abnormal (59%), VNG mainly showed hyporeflexia in the diseased ear. Conclusion In patients suffering from DMD or PMD, with endolymphatic pressure disturbances confirmed by combined DPOAE-phase and EcoG, 3T 3D MRI reveals EH mostly in DMD but rarely in PMD. This seems to confirm that disturbance of endolymphatic pressure precedes EH.

Objective This study aimed to assess the diagnostic value of electrocochleography (ECochG) for identifying endolymphatic hydrops (EH) and to investigate whether integrating multimodal auditory data from ECochG and pure-tone audiometry (PTA) into machine learning models could improve diagnostic accuracy and clinical interpretability. Methods A prospective cohort of 78 patients (156 ears) with a strong clinical suspicion of EH was evaluated between March and June 2024. ECochG and PTA examinations were performed, and extracted parameters were used to develop and validate multiple machine learning models. Diagnostic performance was compared using the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and overall accuracy. Results After excluding six ears with unrecordable ECochG data, 150 ears were analyzed. Models based solely on ECochG-derived features demonstrated limited diagnostic performance (maximum AUC = 0.61). When multimodal hearing data were incorporated, model performance improved substantially. The Light Gradient Boosting Machine (LightGBM) model achieved an AUC of 0.92 and an accuracy of 0.73 for predicting the anatomical distribution of EH. Conclusions Integrating multimodal auditory data into interpretable machine learning models can markedly improve the diagnostic accuracy of endolymphatic hydrops, providing an objective framework to support early clinical diagnosis and management. However, this study is limited by a small sample size and has not yet been validated across multiple centers. Level of evidence Level 3.

The purpose of this study was to clarify the underlying mechanism of vertiginous attacks in Ménière’s disease (MD) while obtaining insight into water homeostasis in the inner ear using a new animal model. We conducted both histopathological and functional assessment of the vestibular system in the guinea-pig. In the first experiment, all animals were maintained 1 or 4 weeks after electrocauterization of the endolymphatic sac of the left ear and were given either saline or desmopressin (vasopressin type 2 receptor agonist). The temporal bones from both ears were harvested and the extent of endolymphatic hydrops was quantitatively assessed. In the second experiment, either 1 or 4 weeks after surgery, animals were assessed for balance disorders and nystagmus after the administration of saline or desmopressin. In the first experiment, the proportion of endolymphatic space in the cochlea and the saccule was significantly greater in ears that survived for 4 weeks after surgery and were given desmopressin compared with other groups. In the second experiment, all animals that underwent surgery and were given desmopressin showed spontaneous nystagmus and balance disorder, whereas all animals that had surgery but without desmopressin administration were asymptomatic. Our animal model induced severe endolymphatic hydrops in the cochlea and the saccule, and showed episodes of balance disorder along with spontaneous nystagmus. These findings suggest that administration of desmopressin can exacerbate endolymphatic hydrops because of acute V2 (vasopressin type 2 receptor)-mediated effects, and, when combined with endolymphathic sac dysfunction, can cause temporary vestibular abnormalities that are similar to the vertiginous attacks in patients with MD.

Middle ear application of gentamicin is a common medical treatment for uncontrolled Ménière's disease. The objective of the study was to evaluate the impact of endolymphatic hydrops on inner ear delivery. Perilymph gentamicin concentrations and correlation with endolymphatic hydrops in an animal model were assessed. A group of 24 guinea pigs was submitted to surgical obstruction of the endolymphatic sac and duct of the right ear. Gentamicin was applied either to the right ear's round window niche or through a transtympanic injection. Perilymph specimens were collected at different times. Histologic morphometry was used to evaluate both turn-specific and overall hydrops degree. In animals with endolymphatic hydrops, lower concentrations of gentamicin were observed after 20 or 120 minutes of exposure and in both types of administration, when compared to controls. This difference reached statistical significance in the round window niche application group (Mann-Whitney, p = 0,007). A negative correlation between perilymphatic gentamicin concentration and hydrops degree could be observed in both groups, after 120 minutes of exposure (Spearman correlation, round window niche p<0,001; TT p = 0,005). The study indicates that the endolymphatic hydrops degree has a negative interference on the delivery of gentamicin into the inner ear following middle ear application.

A fundamental property of mammalian hearing is the conversion of sound pressure into a frequency-specific place of maximum vibration along the cochlear length, thereby creating a tonotopic map. The tonotopic map makes possible systematic frequency tuning across auditory-nerve fibers, which enables the brain to use pitch to separate sounds from different environmental sources and process the speech and music that connects us to people and the world. Sometimes a tone has a different pitch in the left and right ears, a perceptual anomaly known as diplacusis. Diplacusis has been attributed to a change in the cochlear frequency-place map, but the hypothesized abnormal cochlear map has never been demonstrated. Here we assess cochlear frequency-place maps in guinea-pig ears with experimentally-induced endolymphatic hydrops, a hallmark of Ménière’s disease. Our findings are consistent with the hypothesis that diplacusis is due to an altered cochlear map. Map changes can lead to altered pitch, but the size of the pitch change is also affected by neural synchrony. Our data show that the cochlear frequency-place map is not fixed but can be altered by endolymphatic hydrops. Map changes should be considered in assessing hearing pathologies and treatments.