The evolution of hearing and balance.

New genetic tools have allowed researchers to compare how the brainstem auditory and vestibular nuclei develop in embryonic chicks and mice

Mechanisms and Mechanosensitivity: Exceptional Cadherins for Hearing and Balance

Légende manuscrite sur le document original : ''Madras. Quartier de Triplicane. '' -- Géolocalisation approximative centrée sur le quartier de Triplican

Hearing and Balance Survey in Thai Elders

Objective: To survey hearing and balance problems of a sampling group of Thai elders in the central region of Thailand. Methods: A population study was people aged 60 and over who agreed to join the survey at the 14 elderly social associations. The questionnaires were used as a self-report for hearing and balance problems. After ears examination by ENT specialists, the participants underwent air-conduction audiometry for hearing screening. Results: 828 participants 259 (31.3%) males and 569 (68.7%) females, age ranged from 60 to 97 (median=68, mean ± SD = 69.65 ± 6.89 years), had completed screening program for hearing and balance problems using both questionnaires and examinations. There was a statistically significant correlation between self-report hearing loss and severe or profound hearing loss in both ears (P <0.05). All age groups reported dizziness and vertigo but the elderly over 75 years reported more falls with a statistical significance (P=0.021). The elderly who did not report dizziness or vertigo had a1.1-1.6 times higher fall histories than those who reported (P <0.001). The participants who had hypertension and dyslipidemia reported more falls with statistical significances (P=0.025 and 0.036 respectively). Conclusion: Our hearing and balance questionnaires may be used as a tool for screening at a primary care for the elderly > 70 years old especially in those with underlying diseases. Hearing and balance screening will provide early detection and primary intervention to minimize the negative impact in the elderly’s daily life

Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid

Ear care: an update for nurses (part 2)

Impacted cerumen can cause problems ranging from general discomfort to loss of hearing function. In the second of two articles, Kat Millward examines the best methods for softening and removing cerumen from the ear without causing any damage Our ears are essential for both hearing and balance. Up to 4% of the population will have difficulties with their ears relating to impacted cerumen and many of them will present in primary care with ear discomfort or hearing difficulties. In the second of two articles, we review the evidence and recommended best practice for managing impacted cerumen, including ear drops, irrigation, microsuction and instrumentation

Mutations of the Mouse ELMO Domain Containing 1 Gene (Elmod1) Link Small GTPase Signaling to Actin Cytoskeleton Dynamics in Hair Cell Stereocilia

Stereocilia, the modified microvilli projecting from the apical surfaces of the sensory hair cells of the inner ear, are essential to the mechanoelectrical transduction process underlying hearing and balance. The actin-filled stereocilia on each hair cell are tethered together by fibrous links to form a highly patterned hair bundle. Although many structural components of hair bundles have been identified, little is known about the signaling mechanisms that regulate their development, morphology, and maintenance. Here, we describe two naturally occurring, allelic mutations that result in hearing and balance deficits in mice, named roundabout (rda) and roundabout-2J (rda2J). Positional cloning identified both as mutations of the mouse ELMO domain containing 1 gene (Elmod1), a poorly characterized gene with no previously reported mutant phenotypes. The rda mutation is a 138 kb deletion that includes exons 1–5 of Elmod1, and rda2J is an intragenic duplication of exons 3–8 of Elmod1. The deafness associated with these mutations is caused by cochlear hair cell dysfunction, as indicated by conspicuous elongations and fusions of inner hair cell stereocilia and progressive degeneration of outer hair cell stereocilia. Mammalian ELMO-family proteins are known to be involved in complexes that activate small GTPases to regulate the actin cytoskeleton during phagocytosis and cell migration. ELMOD1 and ELMOD2 recently were shown to function as GTPase-activating proteins (GAPs) for the Arf family of small G proteins. Our finding connecting ELMOD1 deficiencies with stereocilia dysmorphologies thus establishes a link between the Ras superfamily of small regulatory GTPases and the actin cytoskeleton dynamics of hair cell stereocilia

Transcriptomic Analyses of Inner Ear Sensory Epithelia in Zebrafish

Analysis of gene expression has the potential to assist in the understanding of multiple cellular processes including proliferation, cell-fate specification, senesence, and activity in both healthy and disease states. Zebrafish model has been increasingly used to understand the process of hearing and the development of the vertebrate auditory system. Within the zebrafish inner ear, there are three otolith organs, each containing a sensory macula of hair cells. The saccular macula is primarily involved in hearing, the utricular macula is primarily involved in balance and the function of the lagenar macula is not completely understood. The goal of this study is to understand the transcriptional differences in the sensory macula associated with different otolith organs with the intention of understanding the genetic mechanisms responsible for the distinct role each organ plays in sensory perception. The sensory maculae of the saccule, utricle, and lagena were dissected out of adult Et(krt4:GFP) zebrafish expressing green fluorescent protein in hair cells for transcriptional analysis. The total RNAs of the maculae were isolated and analyzed by RNA GeneChip microarray. Several of the differentially expressed genes are known to be involved in deafness, otolith development and balance. Gene expression among these otolith organs was very well conserved with less than 10% of genes showing differential expression. Data from this study will help to elucidate which genes are involved in hearing and balance. Furthermore, the findings of this study will assist in the development of the zebrafish model for human hearing and balance disorders. Anat Rec, 303:527-543, 2020. © 2019 American Association for Anatomy

Vestibular effects of diving – а review

Scuba diving is a popular recreational and professional activity with inherent risks. Complications related to barotrauma and decompression illness can pose significant morbidity to a diver’s hearing and balance systems. The common symptoms of otologic dysfunction are ear fullness or pain, hearing loss, tinnitus, and vertigo. Vertigo is one of the most hazardous symptoms to occur during diving. It is frequently accompanied by hearing loss and tinnitus. Vertigo is described in multiple phases of diving. However, many of these reports are not well documented, do not differentiate vertigo from nonvertiginous disequilibrium, or discuss vertigo only as an incidental observation.The purpose of this publication is to review the vestibular effects of diving

Clinical and imaging biomarkers of audiovestibular function in infratentorial superficial siderosis

Disabling hearing loss is known to affect over 400 million people worldwide while the lifetime prevalence of dizziness can be as high as 40%. Rare causes for hearing and balance impairment are often understudied. Infratentorial (classical) superficial siderosis (iSS) is a rare but sometimes disabling complex neurological condition most often associated with hearing and balance impairment, and myelopathy. Olfactory loss has been reported but not yet systematically studied. iSS results from a chronic low-grade and low volume bleeding into the cerebrospinal fluid and the deposition of iron-degradation products (predominantly haemosiderin) in the subpial layers of the central nervous system, with predilection for the cerebellum and the vestibulocochlear nerves. Magnetic resonance imaging (MRI) allows haemosiderin to be visualised in-vivo and is the mainstream diagnostic modality. Due to the assumed rarity of iSS (prevalence of 0.03-0.14%), our research opportunities are limited. Few dedicated studies describe iSS-related audiovestibular (AV) findings, often limited to case-series, with mixed findings. There is currently no robust evidence that the radiological haemosiderin appearances correlate with the objective clinical tests. This project focuses on phenotyping the AV function in iSS and identifies predominantly retrocochlear hearing loss with features suggestive of central auditory dysfunction, and mixed vestibular (predominantly cerebellar) dysfunction. This work introduces and validates an imaging rating scale aiming to capture the anatomical extent of haemosiderin deposits visualised on MRI in a standardised and reproducible way. The scale demonstrates excellent reliability and good validity, with the scores correlating with hearing thresholds. This project estimates the prevalence of MRI-defined iSS in a large UK Biobank sample, similar to other rare neurootological disorders. Using patient/self-report measures, this work captures markedly low health-states of individuals with iSS and identifies possible iSS-specific auditory characteristics. Finally, the work identifies high prevalence of olfactory dysfunction in individuals with iSS

Ear care: an update for nurses (part 1)

A healthy ear is vital not just for hearing, but for balance and for full engagement with the community. In the first of two articles, Kat Millward reviews the anatomy of the ear, outlines methods of dealing with cerumen, and discusses methods of assessment and diagnosis Our ears are essential for both hearing and balance. Up to 4% of the population will have difficulties with their ears relating to impacted cerumen and many of them will present in primary care with ear discomfort or hearing difficulties. In the first of two articles, we review the anatomy and physiology of the ear and cerumen production, followed by a discussion of the key aspects of making an assessment using the SOAP (Subjective, Objective, Assessment, Plan) mnemonic