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Science Translational Medicine Mar 2019Permanent hearing loss affects more than 5% of the world's population, yet there are no nondevice therapies that can protect or restore hearing. Delivery of therapeutics... (Review)
Review
Permanent hearing loss affects more than 5% of the world's population, yet there are no nondevice therapies that can protect or restore hearing. Delivery of therapeutics to the cochlea and vestibular system of the inner ear is complicated by their inaccessible location. Drug delivery to the inner ear via the vasculature is an attractive noninvasive strategy, yet the blood-labyrinth barrier at the luminal surface of inner ear capillaries restricts entry of most blood-borne compounds into inner ear tissues. Here, we compare the blood-labyrinth barrier to the blood-brain barrier, discuss invasive intratympanic and intracochlear drug delivery methods, and evaluate noninvasive strategies for drug delivery to the inner ear.
Topics: Animals; Cochlea; Drug Delivery Systems; Ear, Inner; Hearing Loss; Humans; Permeability; Pharmaceutical Preparations
PubMed: 30842313
DOI: 10.1126/scitranslmed.aao0935 -
Australian Family Physician Apr 2016Dizziness is a common and very distressing presentation in general practice. In more than half of these cases, the dizziness is due to vertigo, which is the illusion of...
BACKGROUND
Dizziness is a common and very distressing presentation in general practice. In more than half of these cases, the dizziness is due to vertigo, which is the illusion of movement of the body or its surroundings. It can have central or peripheral causes, and determining the cause can be difficult.
OBJECTIVE
The aim of this article is to provide a clear framework for approaching patients who present with vertigo. A suggested approach to the assessment of vertigo is outlined.
DISCUSSION
The causes of vertigo may be central (involving the brainstem or cerebellum) or peripheral (involving the inner ear). A careful history and physical examination can distinguish between these causes. The most common causes of vertigo seen in primary care are benign paroxysmal positional vertigo (BPPV), vestibular neuronitis (VN) and Ménière's disease. These peripheral causes of vertigo are benign, and treatment involves reassurance and management of symptoms.
Topics: General Practice; Humans; Labyrinthitis; Medical History Taking; Meniere Disease; Physical Examination; Vertigo; Vestibular Neuronitis
PubMed: 27052132
DOI: No ID Found -
Balkan Medical Journal Sep 2017Morphologically congenital sensorineural hearing loss can be investigated under two categories. The majority of congenital hearing loss causes (80%) are membranous...
Morphologically congenital sensorineural hearing loss can be investigated under two categories. The majority of congenital hearing loss causes (80%) are membranous malformations. Here, the pathology involves inner ear hair cells. There is no gross bony abnormality and, therefore, in these cases high-resolution computerized tomography and magnetic resonance imaging of the temporal bone reveal normal findings. The remaining 20% have various malformations involving the bony labyrinth and, therefore, can be radiologically demonstrated by computerized tomography and magnetic resonance imaging. The latter group involves surgical challenges as well as problems in decision-making. Some cases may be managed by a hearing aid, others need cochlear implantation, and some cases are candidates for an auditory brainstem implantation (ABI). During cochlear implantation, there may be facial nerve abnormalities, cerebrospinal fluid leakage, electrode misplacement or difficulty in finding the cochlea itself. During surgery for inner ear malformations, the surgeon must be ready to modify the surgical approach or choose special electrodes for surgery. In the present review article, inner ear malformations are classified according to the differences observed in the cochlea. Hearing and language outcomes after various implantation methods are closely related to the status of the cochlear nerve, and a practical classification of the cochlear nerve deficiency is also provided.
Topics: Classification; Cochlea; Cochlear Nerve; Ear, Inner; Hearing Loss, Sensorineural; Humans; Osteogenesis; Temporal Bone; Tomography, X-Ray Computed
PubMed: 28840850
DOI: 10.4274/balkanmedj.2017.0367 -
Journal of Radiology Case Reports May 2020Labyrinthitis most commonly results from an infectious and less commonly from an inflammatory process of the inner ear, but it can be associated with temporal bone... (Review)
Review
Labyrinthitis most commonly results from an infectious and less commonly from an inflammatory process of the inner ear, but it can be associated with temporal bone trauma, hemorrhage, or tumor. This inflammation (regardless of the etiology) disrupts the transmission of sensory information from the ear to the brain. Labyrinthitis ossificans is the pathological ossification of the membranous labyrinthine spaces in response to an insult to the inner ear involving membranous labyrinth or the endosteum of the otic capsule. Herein, we present a case of a 67-year-old female with progressive bilateral sensorineural hearing loss and positional vertigo.
Topics: Aged; Bone Diseases; Brain; Female; Humans; Labyrinth Diseases; Labyrinthitis; Ossification, Heterotopic; Temporal Bone
PubMed: 33082921
DOI: 10.3941/jrcr.v14i5.3706 -
Cell Reports Jun 2023Inner ear disorders are among the most common congenital abnormalities; however, current tissue culture models lack the cell type diversity to study these disorders and...
Inner ear disorders are among the most common congenital abnormalities; however, current tissue culture models lack the cell type diversity to study these disorders and normal otic development. Here, we demonstrate the robustness of human pluripotent stem cell-derived inner ear organoids (IEOs) and evaluate cell type heterogeneity by single-cell transcriptomics. To validate our findings, we construct a single-cell atlas of human fetal and adult inner ear tissue. Our study identifies various cell types in the IEOs including periotic mesenchyme, type I and type II vestibular hair cells, and developing vestibular and cochlear epithelium. Many genes linked to congenital inner ear dysfunction are confirmed to be expressed in these cell types. Additional cell-cell communication analysis within IEOs and fetal tissue highlights the role of endothelial cells on the developing sensory epithelium. These findings provide insights into this organoid model and its potential applications in studying inner ear development and disorders.
Topics: Humans; Endothelial Cells; Cochlea; Vestibule, Labyrinth; Epithelium; Organoids
PubMed: 37289589
DOI: 10.1016/j.celrep.2023.112623 -
Audiology & Neuro-otology 2020The peripheral vestibular end organ is considered to consist of semi-circular canals (SCC) for detection of angular accelerations and the otoliths for detection of... (Review)
Review
BACKGROUND
The peripheral vestibular end organ is considered to consist of semi-circular canals (SCC) for detection of angular accelerations and the otoliths for detection of linear accelerations. However, otoliths being phylogenetically the oldest part of the vestibular sensory organs are involved in detection of all motions.
SUMMARY
This study elaborates on this property of the otolith organ, as this concept can be of importance for the currently designed vestibular implant devices. Key Message: The analysis of the evolution of the inner ear and examination of clinical examples shows the robustness of the otolith system and inhibition capacity of the SCC. The otolith system must be considered superior to the SCC system as illustrated by evolution, clinical evidence, and physical principles.
Topics: Humans; Otolithic Membrane; Reflex, Vestibulo-Ocular; Saccule and Utricle; Semicircular Canals; Vestibule, Labyrinth
PubMed: 31927546
DOI: 10.1159/000504595 -
Physiological Research May 2018This review is focused on the unusual composition of the endolymph of the inner ear and its function in mechanoelectrical transduction. The role of K(+) and Ca(2+) in... (Review)
Review
This review is focused on the unusual composition of the endolymph of the inner ear and its function in mechanoelectrical transduction. The role of K(+) and Ca(2+) in excitatory influx, the very low Na(+), Ca(2+) and Mg(2+) concentrations of endolymph, stereocilia structure of hair cells and some proteins involved in mechanosensory signal transduction with emphasis on auditory receptors are presented and analyzed in more details. An alternative hypothetical model of ciliary structure and endolymph with a 'normal' composition is discussed. It is concluded that the unique endolymph cation content is more than an energy saving mechanism that avoids disturbing circulatory vibrations to achieve a much better mechanosensory resolution. It is the only possible way to fulfil the requirements for a precise ciliary mechanoelectrical transduction in conditions where pressure events with quite diverse amplitudes and duration are transformed into adequate hair cell membrane depolarizations, which are regulated by a sensitive Ca(2+)-dependent feedback tuning.
Topics: Animals; Ear, Inner; Endolymph; Hair Cells, Auditory, Inner; Humans; Mechanotransduction, Cellular
PubMed: 29303598
DOI: 10.33549/physiolres.933684 -
Purinergic Signalling Jun 2022The inner ear comprises the cochlea and vestibular system, which detect sound and acceleration stimulation, respectively. The function of the inner ear is regulated by... (Review)
Review
The inner ear comprises the cochlea and vestibular system, which detect sound and acceleration stimulation, respectively. The function of the inner ear is regulated by ion transport activity among sensory epithelial cells, neuronal cells, non-sensory epithelial cells, and luminal fluid with a unique ionic composition of high [K] and low [Na], which enables normal hearing and balance maintenance. One of the important mechanisms regulating ion transport in the inner ear is purinergic signaling. Various purinergic receptors are distributed throughout inner ear epithelial cells and neuronal cells. To date, most studies have focused on the role of purinergic receptors in the cochlea, and few studies have examined these receptors in the vestibular system. As purinergic receptors play an important role in the cochlea, they would likely do the same in the vestibular system, which is fairly similar to the cochlea in cellular structure and function. Based on available studies performed to date, purinergic signaling is postulated to be involved in the regulation of ion homeostasis, protection of hair cells, otoconia formation, and regulation of electrical signaling from the sensory epithelium to vestibular neurons. In this review, the distribution and roles of purinergic receptors in the peripheral vestibular system are summarized and discussed.
Topics: Cochlea; Ear, Inner; Receptors, Purinergic; Signal Transduction; Vestibular System
PubMed: 35344126
DOI: 10.1007/s11302-022-09855-5 -
Journal of Neurophysiology Mar 2019The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS)... (Review)
Review
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
Topics: Animals; Biomechanical Phenomena; Humans; Semicircular Canals; Vestibular Diseases
PubMed: 30565972
DOI: 10.1152/jn.00708.2018 -
Hearing Research Oct 2018Drug delivery to the inner ear is an ideal method to treat a wide variety of otologic conditions. A broad range of potential applications is just beginning to be... (Review)
Review
Drug delivery to the inner ear is an ideal method to treat a wide variety of otologic conditions. A broad range of potential applications is just beginning to be explored. New approaches combine principles of inner ear pharmacokinetics with emerging technologies of drug delivery including novel delivery systems, drug-device combinations, and new categories of drugs. Strategies include cell-specific targeting, manipulation of gene expression, local activation following systemic delivery, and use of stem cells, viral vectors, and gene editing systems. Translation of these therapies to the clinic remains challenging given the potential risks of intracochlear and intralabyrinthine trauma, our limited understanding of the etiologies of particular inner ear disorders, and paucity of accurate diagnostic tools at the cellular level. This review provides an overview of future methods, delivery systems, disease targets, and clinical considerations required for translation to clinical medicine.
Topics: Animals; Biomedical Research; Diffusion of Innovation; Drug Delivery Systems; Ear, Inner; Forecasting; Genetic Therapy; Hearing; Hearing Loss; Humans; Labyrinth Diseases; Pharmaceutical Preparations; Pharmacokinetics
PubMed: 29804723
DOI: 10.1016/j.heares.2018.05.009