The Physiologic Role of Corticosteroids in Menière's Disease: An Update on Glucocorticoid-mediated Pathophysiology and Corticosteroid Inner Ear Distribution

Advance and Application of Single-cell Transcriptomics in Auditory Research

Hearing loss and deafness, as a worldwide disability disease, have been troubling human beings. However, the auditory organ of the inner ear is highly heterogeneous and has a very limited number of cells, which are largely uncharacterized in depth. Recently, with the development and utilization of single-cell RNA sequencing (scRNA-seq), researchers have been able to unveil the complex and sophisticated biological mechanisms of various types of cells in the auditory organ at the single-cell level and address the challenges of cellular heterogeneity that are not resolved through by conventional bulk RNA sequencing (bulk RNA-seq). Herein, we reviewed the application of scRNA-seq technology in auditory research, with the aim of providing a reference for the development of auditory organs, the pathogenesis of hearing loss, and regenerative therapy. Prospects about spatial transcriptomic scRNA-seq, single-cell based genome, and Live-seq technology will also be discussed.

Uptake of gadolinium and dexamethasone in rat inner ear and facial nerve using different administrations

BACKGROUND

The pathway by which drugs are injected subcutaneously behind the ear to act on the inner ear has not been fully elucidated.

OBJECTIVES

To compare the uptake of gadopentetate dimeglumine (Gd-DTPA) and dexamethasone (Dex) in the cochlea and facial nerve of rats following different administrations.

MATERIALS AND METHODS

Magnetic resonance imaging was applied to observe the distribution of Gd-DTPA in the facial nerve and inner ear. We observed the uptake of Dex after it was injected with different methods.

RESULTS

Images of the intravenous (IV) and intramuscular (IM) groups showed that the bilateral cochlea of the rat was visualized almost simultaneously. While in the left post-auricular (PA) injection group, it was asynchronous. The maximum accumulation (Cmax) of the Gd in the left facial nerve of the PA group (35.406 ± 5.32) was substantially higher than that of the IV group (16.765 ± 3.7542) (p < .01).

CONCLUSIONS

Compared with systemic administration, PA has the advantages of long Gd and Dex action time and high accumulation concentration to treat facial nerve diseases.

SIGNIFICANCE

The distribution of Gd and Dex in the inner ear and facial nerve of rats following PA injection might be unique.

Meniere's disease: Pathogenesis, treatments, and emerging approaches for an idiopathic bioenvironmental disorder

Meniere's disease (MD) is a severe inner ear condition known by debilitating symptoms, including spontaneous vertigo, fluctuating and progressive hearing loss, tinnitus, and aural fullness or pressure within the affected ear. Prosper Meniere first described the origins of MD in the 1860s, but its underlying mechanisms remain largely elusive today. Nevertheless, researchers have identified a key histopathological feature called Endolymphatic Hydrops (ELH), which refers to the excessive buildup of endolymph fluid in the membranous labyrinth of the inner ear. The exact root of ELH is not fully understood. Still, it is believed to involve several biological and bioenvironmental etiological factors such as genetics, autoimmunity, infection, trauma, allergy, and new theories, such as saccular otoconia blocking the endolymphatic duct and sac. Regarding treatment, there are no reliable and definitive cures for MD. Most therapies focus on managing symptoms and improving the overall quality of patients' life. To make significant advancements in addressing MD, it is crucial to gain a fundamental understanding of the disease process, laying the groundwork for more effective therapeutic approaches. This paper provides a comprehensive review of the pathophysiology of MD with a focus on old and recent theories. Current treatment strategies and future translational approaches (with low-level evidence but promising results) related to MD are also discussed, including patents, drug delivery, and nanotechnology, that may provide future benefits to patients suffering from MD.

Long-term efficacy of dexamethasone treatment via tympanic antrum catheterization for intractable Meniere's disease

Objective

To explore the long-term efficacy and safety of dexamethasone treatment via tympanic antrum catheterization (TAC) in intractable Meniere's disease (MD).

Methods

In this retrospective analysis, 60 unilateral intractable MD patients treated with TAC in our hospital from January 2020 to August 2020 were followed for 2 years. Fifty patients who underwent endolymphatic sac decompression (ESD) and 50 patients who accepted intratympanic steroids (ITS) were established as the control groups. Vertigo control, hearing level, tinnitus, aural fullness and functional level were assessed during the study.

Results

The effective vertigo control rate of intractable MD patients with TAC treatment was 76.7% (46/60) after 2 years follow-up, with a complete control rate of 58.3% (35/60) and a substantial control rate of 18.3% (11/60). The vertigo control rate of TAC was comparable to that of ESD (χ2 = 0.313, p &gt; 0.05), and significantly higher than that of ITS (χ2 = 4.380, p &lt; 0.05). The hearing loss rate of these patients was 10.8% (4/37), which was not significantly different from the control groups (χ2 = 2.452, p &gt; 0.05). The tinnitus improvement rate of patients with TAC was 56.7% (34/60), which was significantly higher than that of patients with ESD (χ2 =11.962, p &lt; 0.001) and ITS (χ2 =15.278, p &lt; 0.001). The aural fullness improvement rate in the TAC group was 56.7% (34/60), which was significantly higher than that in the ESD (χ2 = 11.962, p &lt; 0.001) and ITS groups (χ2 = 5.635, p &lt; 0.05). The functional level improvement rate in the TAC group was 71.7% (43/60), which was much higher than that in the ITS group (χ2 = 17.256, p &lt; 0.001), but there was no significant difference between TAC and ESD (χ2 = 0.410, p &gt; 0.05). No patients had complications or adverse reactions following TAC treatment.

Conclusion

Dexamethasone treatment via TAC can effectively control vertigo attacks and improve related symptoms of intractable MD patients, providing valuable new insights into the treatment of MD.

Repurposable Drugs That Interact with Steroid Responsive Gene Targets for Inner Ear Disease

Corticosteroids, oral or transtympanic, remain the mainstay for inner ear diseases characterized by hearing fluctuation or sudden changes in hearing, including sudden sensorineural hearing loss (SSNHL), Meniere's disease (MD), and autoimmune inner ear disease (AIED). Despite their use across these diseases, the rate of complete recovery remains low, and results across the literature demonstrates significant heterogeneity with respect to the effect of corticosteroids, suggesting a need to identify more efficacious treatment options. Previously, our group has cross-referenced steroid-responsive genes in the cochlea with published single-cell and single-nucleus transcriptome datasets to demonstrate that steroid-responsive differentially regulated genes are expressed in spiral ganglion neurons (SGN) and stria vascularis (SV) cell types. These differentially regulated genes represent potential druggable gene targets. We utilized multiple gene target databases (DrugBank, Pharos, and LINCS) to identify orally administered, FDA approved medications that potentially target these genes. We identified 42 candidate drugs that have been shown to interact with these genes, with an emphasis on safety profile, and tolerability. This study utilizes multiple databases to identify drugs that can target a number of druggable genes in otologic disorders that are commonly treated with steroids, providing a basis for establishing novel repurposing treatment trials.

Potential nanotechnology-based diagnostic and therapeutic approaches for Meniere's disease

Meniere's disease (MD) is a progressive inner ear disorder involving recurrent and prolonged episodes or attacks of vertigo with associated symptoms, resulting in a significantly reduced quality of life for sufferers. In most cases, MD starts in one ear; however, in one-third of patients, the disorder progresses to the other ear. Unfortunately, the etiology of the disease is unknown, making the development of effective treatments difficult. Nanomaterials, including nanoparticles (NPs) and nanocarriers, offer an array of novel diagnostic and therapeutic applications related to MD. NPs have specific features such as biocompatibility, biochemical stability, targetability, and enhanced visualization using imaging tools. This paper provides a comprehensive and critical review of recent advancements in nanotechnology-based diagnostic and therapeutic approaches for MD. Furthermore, the crucial challenges adversely affecting the use of nanoparticles to treat middle ear disorders are investigated. Finally, this paper provides recommendations and future directions for improving the performances of nanomaterials on theragnostic applications of MD.

Recovery of Unaided Hearing After Cochlear Implantation in Patient With Bilateral Menière's Disease

OBJECTIVE

To report a novel occurrence of unaided hearing recovery after cochlear implantation in a patient with Menière's disease.

PATIENTS

A 49-year-old woman with bilateral Menière's disease and vestibular migraine.

INTERVENTIONS

Cochlear implantation.

MAIN OUTCOME MEASURES

Postoperative unaided and aided pure tone thresholds and speech recognition measures.

RESULTS

Six-month postoperative unaided hearing in the implanted ear was in the moderate sensorineural hearing loss range with a speech reception threshold of 45 dB and word recognition score of 95%, representing a significant improvement from preoperative hearing, which was in the profound sensorineural hearing loss range with an unaided speech awareness threshold of 75 dB and inability to perform speech recognition testing. Aided testing also demonstrated an expected postoperative improvement after 6 months with a CNC word and AzBio in quiet score of 96% and 93%, respectively, from 0% and 9% preoperatively.

CONCLUSION

Unaided hearing improvement after cochlear implantation in a patient with Menière's disease is unexpected, but possible and might lend insight into the poorly understood underlying mechanisms of sensorineural hearing loss in patients with Menière's disease.

In silico Single-Cell Analysis of Steroid-Responsive Gene Targets in the Mammalian Cochlea

Background

Treatment of many types of hearing instability in humans, including sudden sensorineural hearing loss, Meniere's disease, and autoimmune inner ear disease, rely heavily on the utilization of corticosteroids delivered both by oral and transtympanic routes. Despite this use, there is heterogeneity in the response to treatment with corticosteroids in humans with these diseases. The mechanisms by which corticosteroids exert their effect and the cell types in which they exert their effects in the inner ear remain poorly characterized. In this study, we localize steroid-responsive genes to cochlear cell types using previously published transcriptome datasets from the mammalian cochlea.

Methods

Steroid-responsive genes were localized to specific cochlear cell types using existing transcriptome datasets from wild-type mammalian cochlea exposed to systemic and transtympanic steroids, as well as previously published single-cell and single-nucleus RNA-sequencing datasets from the mammalian cochlea. Gene ontology (GO) analysis of differentially expressed genes (DEGs) was performed using PANTHER to investigate cellular processes implicated in transtympanic vs. systemic steroid action in the cochlea.

Results

Steroid-responsive genes were localized to specific cell types and regions in the cochlea including the stria vascularis, organ of Corti, and spiral ganglion neurons (SGN). Analyses demonstrate differential prevalence of steroid-responsive genes. GO analysis demonstrated steroid-responsive DEGs in the SGN to be associated with angiogenesis, apoptosis, and cytokine-mediated anti-inflammatory pathways.

Conclusions

Single-cell and single-nucleus transcriptome datasets localize steroid-responsive genes to specific regions in the cochlea. Further study of these regionally-specific steroid-responsive genes may provide insight into the mechanisms of and clinical response to corticosteroids in diseases of hearing instability.

Current Insights into Treating Vertigo in Older Adults

The number of older people has been increasing over recent decades in Western populations. Dizziness, imbalance, and vertigo constitute some of the most common complaints in older patients, and risk of falling is the most frequent and worrying consequence. It has been reported that 15–20% of the adult population experiences these debilitating symptoms. Among the diseases that may be associated with vertigo, the three classes of otological, central, and functional (psychological) dizziness may be distinguished. Overall, vestibular disorders account for 48% of vertiginous complaints in the older population. The main focus of this article is to review the forms of pharmacotherapy for vertigo, especially with regard to older patients, who may be treated simultaneously with other drugs for different comorbidities. Interactions with other drugs should be considered in the choice of a particular course of treatment. Moreover, overuse of pharmacotherapy for the management of vertigo in the elderly may prevent the development of the central compensatory mechanism that sustains both static and dynamic imbalance after a vertiginous crisis. In the majority of patients, vestibular and physical rehabilitation are strongly advised and rarely contraindicated.

Current status on researches of Meniere's disease: a review

Background: Meniere's disease (MD) is a complex and multifactorial inner ear disease. The etiology of MD is unclear. Significant progress had been made in diagnosis and treatment. Complete cure for this disease is still impossible.Objectives: This review covers the updated research results in MD in the past decades.Material and methods: Recent publications were critically reviewed.Results: The relationship between Endolymphatic hydrops and Meniere symptoms requires further study. Direct visualization of EH is achieved by special sequences of inner ear MRI. Appearance of EH could be observed in MD patients both in symptomatic and asymptomatic ears. Visualization of EH in vivo might make a great substantial improvement in diagnose of MD. The first goal of the management of MD is to reduce the attack frequency. Several safe and effective medical and surgical therapies are practiced to help patients to control vertigo and preserve hearing.Conclusions and significance: There has been no major breakthrough in the pathogenesis research of MD in recent years. Visualization of EH in vivo might make a great substantial improvement in diagnose of MD. Clinicians still have few effective ways to alleviate the progress of the disease.