Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Inner ear”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2006

NF-kappaB mediated glucocorticoid response in the inner ear after acoustic trauma.

The inner ear of humans and experimental animals demonstrate an abundance of glucocorticoid receptors (GR). Glucocorticoids (GC) are widely used to treat different hearing disorders; yet the mechanisms of GC action on the inner ear are unknown. We demonstrate how GR can directly modulate hearing sensitivity in response to a moderate acoustic trauma that results in a hearing loss (10-30 dB). The GC agonist (dexamethasone) and the drugs (metyrapone + RU 486) showed opposing effects on hearing threshold shifts. GC agonist (dexamethasone) decreased the hearing threshold whereas pre-treatment with a GC synthesis inhibitor (metyrapone) in combination with a GR antagonist (RU 486) exacerbated auditory threshold shifts (25-60 dB) after acoustic trauma with statistically significant increase in GR mRNA and GR protein compared with the vehicle and acoustic trauma group. Acoustic trauma caused a significant increase in the nuclear transport of NF-kappaB, whereas pre-treatment with the drugs (metyrapone and RU 486) blocked NF-kappaB nuclear transport into spiral ganglion nuclei. An NF-kappaB inhibitor, pyrrolidine dithiocarbamate ammonium blocked the trauma-induced translocation of NF-kappaB and resulted in a hearing loss (45-60) dB. These results indicate that several factors define the responsiveness of the inner ear to GC, including the availability of ligand or receptor, and the nuclear translocation of GR and NF-kappaB. These findings will further our understanding of individual GC responsiveness to steroid treatment, and will help improve the development of pharmaceuticals to selectively target GR in the inner ear for individuals with increased sensitivity to acoustic trauma.

Acoustic Stimulation↗
PubMed2003

Cellular localization of TWIK-1, a two-pore-domain potassium channel in the rodent inner ear.

K(+) channels in the inner ear regulate the secretion and homeostasis of K(+), i.e. the flux of K(+) ions required to ensure good mechanosensory transduction. We studied the expression and cellular localization of TWIK-1 and TWIK-2, two-pore-domain K(+) channels responsible for background K(+) currents. Reverse transcription-polymerase chain reaction showed that TWIK-1 mRNA is present in the vestibular end organs, vestibular ganglion and cochlea. In contrast, the TWIK-2 mRNA was not detected in the inner ear. Immunocytochemical experiments using confocal microscopy showed that TWIK-1 is specifically localized in 'non-sensory' cells of the inner ear, in the dark cells of the vestibule and in the strial marginal cells of the cochlea. All of these cell types secrete and regulate the K(+) endolymph production and homeostasis. The labeling was strictly limited to the apical membranes of these cells. TWIK-1 was also detected in the cytoplasm of the large neurons of vestibular ganglion and their fibers. The finding that TWIK-1 is specifically distributed in certain areas of the inner ear suggests that this type of K(+) channel plays a role in the regulation of K(+) homeostasis in dark cells and in strial marginal cells. This role has yet to be identified.

Aging↗
PubMed2007

SLC26A4 mutations are associated with a specific inner ear malformation.

BACKGROUND AND AIM: Inner ear anomalies have been reported in approximately 30% of children with early onset deafness. Identification of causative genetic factors in a large proportion of these patients was not successful. Mutations in the SLC26A4 gene have been detected in individuals with enlarged vestibular aqueduct (EVA) or Mondini dysplasia. We aimed to characterize the inner ear anomalies associated with SLC26A4 mutations. METHODS: The SLC26A4 gene has been screened for mutations in 16 subjects from 14 unrelated Turkish families with a variety of inner ear anomalies ranging from Michel aplasia to incomplete partition-II and EVA. None of the patients was diagnosed to have a recognizable genetic syndrome. Additional four patients with Pendred syndrome from three families were included. RESULTS: Only one patient with EVA was found to have a heterozygous mutation (c.1586delT) in SLC26A4. All patients with Pendred syndrome had homozygous mutations and were noted to have either EVA or EVA associated with incomplete partition-II on the computed tomography of the temporal bone. CONCLUSION: SLC26A4 mutations are not associated with a large spectrum of inner ear anomalies. They, instead, result in a specific morphological appearance consistent with EVA or incomplete partition-II.

Adolescent↗
PubMed1996

Clinical evaluation and treatment of immune-mediated inner ear disease.

Immune-mediated inner ear disease, first described by McCabe in 1979, typically presents with an idiopathic, rapidly progressive bilateral sensorineural hearing loss. The course of the hearing loss occurs over weeks to months. It may occur in both sexes and at a variety of ages, but is most common in middle-aged females. It may be accompanied by tinnitus, Meniere's-like vertigo, or more commonly, ataxia or unsteadiness. Approximately 30% of patients will have associated systemic immune-mediated disease. Although refinements in laboratory tests for specific inner ear antigens are being made, and non-specific laboratory indicators of inflammatory or systemic immune disease may be useful in confirming the diagnosis, the most important diagnostic finding is the improvement in hearing seen with a trial of immunosuppressants. This report includes a typical evaluation of the patient with suspected immune-mediated inner ear disease and an illustrative case. Sensorineural hearing loss due to immune-mediated inner ear disease, although unusual as a cause of hearing loss, is important to recognize because early diagnosis and treatment can have a marked effect on the clinical outcome.

Aged↗
PubMed2007

The inner ear and the neurologist.

Inner ear disorders are common and patients with vestibular failure often present to a neurology clinic because of their dizziness, gait unsteadiness and oscillopsia. Vestibular disorders can be divided into peripheral and central vestibular disorders. Most of the peripheral vestibular disorders have a clinical diagnosis, and a thorough history and examination will often provide a clear direction as to the diagnosis. Correct diagnosis allows treatment for many of the peripheral and central vestibular disorders. As inner ear damage is generally irreversible, early diagnosis allowing prompt treatment is important. The aim of this review is to discuss some audiovestibular conditions that may well appear in a neurology clinic, and to discuss some recent advances within the audiovestibular field that may be of interest to neurologists. Some of the most common audiovestibular conditions will be discussed along side more uncommon conditions.

Diagnosis, Differential↗
PubMed1992

Creatine kinase in epithelium of the inner ear.

Epithelium of the inner ear in the gerbil and mouse was examined immunocytochemically for presence of creatine kinase (CK). Marginal cells of the cochlear stria vascularis and dark cells and transitional cells of the vestibular system were found to contain an abundance of the MM isozyme (MM-CK). CK in these cells concurs with that which is coupled to Na,K-ATPase in other cells and is considered to supply ATP for the Na,K-ATPase that mediates the high KCl of endolymph. Inner hair cells revealed content of the BB isozyme and in this respect resembled the energy-transducing photoreceptor cells in retina. In addition, outer phalangeal (Deiters') cells stained for both MM- and BB-CK whereas inner phalangeal cells evidenced content of only the BB isozyme. Immunolocalization of CK appeared similar in mouse and gerbil inner ear. Specificity of the staining was affirmed by observations in agreement with those reported for CK in various cell types and by staining with antisera from more than one source.

Animals↗
PubMed2004

Suppression of neural fate and control of inner ear morphogenesis by Tbx1.

Inner ear sensory organs and VIIIth cranial ganglion neurons of the auditory/vestibular pathway derive from an ectodermal placode that invaginates to form an otocyst. We show that in the mouse otocyst epithelium, Tbx1 suppresses neurogenin 1-mediated neural fate determination and is required for induction or proper patterning of gene expression related to sensory organ morphogenesis (Otx1 and Bmp4, respectively). Tbx1 loss-of-function causes dysregulation of neural competence in otocyst regions linked to the formation of either mechanosensory or structural sensory organ epithelia. Subsequently, VIIIth ganglion rudiment form is duplicated posteriorly, while the inner ear is hypoplastic and shows neither a vestibular apparatus nor a coiled cochlear duct. We propose that Tbx1 acts in the manner of a selector gene to control neural and sensory organ fate specification in the otocyst.

Animals↗
PubMed2004

Programmed cell death in the development of the vertebrate inner ear.

Programmed cell death is known to be an essential process for accurate ontogeny during the normal development of the inner ear. The inner ear is a complex sensory organ responsible for equilibrium and sound detection in vertebrates. In all vertebrates, the inner ear develops from a single ectodermic patch on the surface of the embryo's head, which undergoes a series of morphological changes to give rise to the complex structure of the adult inner ear. Enlargement and morphogenesis of the inner ear primordium is likely to depend on cellular division, growth, migration, differentiation and apoptosis. Here we describe the regions of programmed cell death that contribute to the final morphological aspect of the adult inner ear. The few studies that focus on the molecules that control this process during inner ear development indicate that the molecules and intracellular signaling pathways activated during the apoptotic response in the inner ear are similar to the previously described for the nervous system. In this review, we will describe some of the growth factors and key pathways that regulate pro- and anti-apoptotic signals and how they cross talk to determine the apoptotic or survival fate of cells in the development of the inner ear.

Animals↗
PubMed2003

Pharmacologic manipulation of the labyrinth with novel and traditional agents delivered to the inner ear.

We describe the methodology and rationale behind the delivery of therapeutic medicines to the inner ear. The inner ear has long been impervious to pharmacologic manipulation. This is most likely the result of a protective mechanism called the blood-labyrinth barrier, whose function closely resembles that of the blood-brain barrier. This protective barrier impedes the clinician's ability to treat inner ear diseases with systemically administered medications. Since 1935, otolaryngologists have attempted to manipulate the inner ear with trans-tympanically injected medicines. Success has varied widely, but medicinal ablation of vestibular function can be achieved in this manner. Unfortunately, the auditory system is also at great risk from any medicine that is delivered to the inner ear via the middle ear. Over the past 10 years, significant improvements in drug delivery have allowed for more "titratable" treatment, which has reduced (but not eliminated) the risk of permanent hearing loss. In this article, we discuss both novel and time-tested methods of delivering medicines to the inner ear. We also review the classes of medications that alter inner ear function and the attendant risks of such treatments.

Aminoglycosides↗
PubMed2002

Chemical perfusion of the inner ear.

In general, chemical perfusion therapy of inner ear disease is safe, inexpensive, and easy to perform. High inner ear medication concentrations can be achieved while minimizing systemic side effects. Most delivery methods are minimally invasive and can be performed in the office. The treatment is usually well accepted by patients. Vertigo control rates for Meniere's disease have been excellent--rivaling other prominent surgical treatments--allowing intratympanic therapy to become the most prominent first-line treatment for Meniere's disease. Side effects of ototoxicity occurring in approximately 30% of patients remain as one of the primary hurdles to overcome. Most patients who experience hearing loss, however, do not complain of the loss and are simply happy to be free of their vertigo attacks. The use of oral steroids to rescue and preserve hearing during gentamicin perfusion remain promising, and complete recovery and even hearing improvement have been observed [30]. Steroid perfusion of the inner ear also is variably effective for the treatment of SSHL, and is particularly indicated when oral steroids fail or are contraindicated due to other health reasons. Many inner ear perfusion methods and philosophies of treatment exist. Each technique has its associated advantages and disadvantages, and the individual surgeon must decide which technique to use in concordance with the patient's disease and expectations. In the future, new medications likely will be developed to treat certain types of inner ear disease, including SSHL, tinnitus, and various forms of vertigo. These medications can be administered by direct chemical perfusion of the inner ear.

Adrenal Cortex Hormones↗
PubMed1995

Detection of inner ear disease autoantibodies by immunoblotting.

To define further the character of autoantibodies against the inner ear in patients with inner ear disease, Autoantibodies in sera from 82 patients with inner ear disease were investigated by immunoblotting. The inner ear antigens were extracted from Hartley guinea pigs. Brain, kidney, lung, heart and liver extracts were also prepared. Antibodies against the inner ear were found in 32 of 82 (39%) patients with inner ear disease. These sera reacted with the 30 and 58 kDa bands of the inner ear extracts. The 30 kDa band was detected in sera from patients with various inner ear diseases, while the 58 kDa band reacted with sera of patients with idiopathic progressive sensorineural hearing loss. Only two of the 52 normal control sera had a very faint band at 30 kDa. Sixteen of 32 positive sera were then used to probe Western blots of the brain, kidney, lung heart and liver extracts. The 58 kDa band was also found in the protein extracts of the brain, the lung, and the liver. On the other hand, preliminary purification of the 30 and 58 kDa proteins from the inner ear extracts were achieved by anion exchange chromatography. These results show that antibodies in sera from patients with inner ear disease reacted with at least two polypeptide bands (30 and 58 kDa) of guinea pig inner ear extracts, and the 58 kDa antigenic epitope was not cochlea specific.

Adolescent↗
PubMed1993

[Deafness caused by malformation of the inner ear. Current contribution of x-ray computed tomography].

Hearing loss due to malformations of the auditory system may involve morphologic abnormalities of the external canal, the middle ear, or the inner ear. Various combined malformations are possible. Audiologic assessment and computed tomography make it possible to perform a precise diagnostic evaluation of inner ear malformations. In a series of 71 children with congenital sensorineural hearing loss, 31 had computed tomographic evidence of malformations. Since 19 children had bilateral lesions, a total of 50 ears were studied. The cochleovestibular abnormalities were typed and correlated to the severity and progression of hearing impairment. The 3 most frequently encountered malformations were: 1) isolated large cochlear aqueduct (n = 12), 2) large vestibular aqueduct (n = 8) and 3) the Mondini malformation (n = 7). The most severe hearing losses were associated with cochlear hypoplasia and incomplete cochlear segmentation. The severity of hearing impairment decreased with the following abnormalities in the order given: 1) large cochlear aqueduct, 2) Mondini malformation and 3) large vestibular aqueduct. Among the 15 patients with progressive hearing loss, 13 had large cochlear aqueducts either isolated or concomitant with other lesions. While certain evident abnormalities, such as cochlear aplasia or Mondini malformation, are relatively easy to diagnose, other more subtle morphologic changes, such as large cochlear aqueduct, still need to be better defined according to precise criteria for radiographic evaluation.

Child↗
PubMedDate not supplied

Cochlear pathophysiology associated with inner ear immune responses.

The effects of primary and secondary inner ear immune responses were investigated in the guinea pig. Subjects were immunized with keyhole limpet hemocyanin (KLH). Serum and perilymph anti-KLH titers, cochlear microphonic (CM) and VIII nerve N1 compound action potential (AP) thresholds, and cochlear morphology were examined at 2 or 4 weeks post-inner ear KLH inoculation. Primary inner ear immunized subjects developed serum and perilymph anti-KLH titers, exhibited minimal cochlear histopathology and showed only small changes in CM and AP thresholds at 2 or 4 weeks post-inner ear inoculation. Secondary immune response animals, those which were systemically immunized with KLH prior to inner ear challenge, showed significant serum and perilymph anti-KLH titers, and normal CM and AP thresholds at the time of inner ear challenge. At 2 or 4 weeks following inner ear challenge, secondary immunized animals showed very significant increases in CM and AP thresholds, and marked cochlear histopathology. We conclude that secondary inner ear challenge results in significant cochlear pathophysiology, while primary inner ear immunization does not.

Action Potentials↗
PubMed1987

Factors affecting the onset of inner ear function.

The developing inner ear receptors have a very significant influence on the onset of stato-acoustic function and on its evolution. The factors which prevent the stato-acoustic system from functioning are called 'the limiting factors'. At present, it is possible to postulate that these factors are restricted to the inner ear cells and related structures. At least four places are particularly relevant for the onset of function: (1) connections of the apical part of hair cell with the tectorial membrane; (2) the internal structure of hair cell; (3) connections between the base of the hair cell and nerve fibers; (4) the ganglion cell with its processes. Special emphasis is devoted to the apical part of the inner hair cell and its connections to the tectorial membrane which are considered as very important for the onset of the cochlear function. For the labyrinth, it is technically difficult to determine precisely the onset of function because of its early prenatal onset. Nevertheless, it is postulated that the limiting factors for the onset of function are also related to certain components of hair cells.

Animals↗
PubMed2004

Islet-1 expression in the developing chicken inner ear.

The cell types of the inner ear originate from the otic placode, a thickened layer of ectoderm adjacent to the developing hindbrain. The placode invaginates and forms the otic pit, which pinches off as a small vesicle called the otocyst. Presumptive cochleovestibular neurons delaminate from the anterior ventral part of the otocyst and form the cochleovestibular ganglion of the inner ear. Here we show that the LIM/homeodomain protein islet-1 is expressed in cells of the ventral part of the otic placode and that this ventral expression is maintained at the otic pit and the otocyst stages. Auditory and vestibular neurons originate from this islet-1-positive zone of the otocyst, and these neurons maintain islet-1 expression until adulthood. We also demonstrate that islet-1 becomes up-regulated in the presumptive sensory epithelia of the inner ear in regions that are defined by the expression domains of BMP4. The up-regulation of islet-1 in developing inner ear hair and supporting cells is accompanied by down-regulation of Pax-2 in these cell types. Islet-1 expression in hair and supporting cells persists until early postnatal stages, when the transcriptional regulator is down-regulated in hair cells. Our data is consistent with a role for islet-1 in differentiating inner ear neurons and sensory epithelia cells, perhaps in the specification of cellular subtypes in conjunction with other LIM/homeodomain proteins.

Actins↗
PubMed2005

Role of the hindbrain in dorsoventral but not anteroposterior axial specification of the inner ear.

An early and crucial event in vertebrate inner ear development is the acquisition of axial identities that in turn dictate the positions of all subsequent inner ear components. Here, we focus on the role of the hindbrain in establishment of inner ear axes and show that axial specification occurs well after otic placode formation in chicken. Anteroposterior (AP) rotation of the hindbrain prior to specification of this axis does not affect the normal AP orientation and morphogenesis of the inner ear. By contrast, reversing the dorsoventral (DV) axis of the hindbrain results in changing the DV axial identity of the inner ear. Expression patterns of several ventrally expressed otic genes such as NeuroD, Lunatic fringe (Lfng) and Six1 are shifted dorsally, whereas the expression pattern of a normally dorsal-specific gene, Gbx2, is abolished. Removing the source of Sonic Hedgehog (SHH) by ablating the floor plate and/or notochord, or inhibiting SHH function using an antibody that blocks SHH bioactivity results in loss of ventral inner ear structures. Our results indicate that SHH, together with other signals from the hindbrain, are important for patterning the ventral axis of the inner ear. Taken together, our studies suggest that tissue(s) other than the hindbrain confer AP axial information whereas signals from the hindbrain are necessary and sufficient for the DV axial patterning of the inner ear.

Animals↗
PubMed2006

[Cerebrospinal fluid leak due to inner ear malformations].

A case of inner ear anomalies associated with recurrent meningitis found in a 66-year-old female is reported. The patient had had 2 episodes of meningitis in the previous one year period. Multidetector-row CT of the temporal bone and three-demensional fast imaging employing steady-state acquisition MRI revealed dysplasia of the bony labyrinth and enlarged fundus of the internal auditory canal (IAC). During surgical treatment, we confirmed the cerebrospinal fluid (CSF) leakage through a bony defect in the stapedial footplate. The inner ear was obliterated and contained small pieces of temporal fascia. A meningitis or CSF leakage due to inner ear malformation is extreamly rear condition for neurosurgeon. Though we always have to take it into condideration as a cause of CSF leakage.

Aged↗
PubMed1995

The localization and specificity of guinea pig inner ear antigenic epitopes.

In this study, we investigated the relative localization of some antigenic epitopes in the inner ear. The inner ear protein antigens were extracted from various parts of the guinea pig inner ear. Brain, kidney, lung, heart and liver extracts were also obtained. We found by SDS-polyacrylamide gel electrophoresis that total inner ear extracts separated into three high concentration polypeptide bands with molecular weights of approximately 30, 42, 58 kd and three low density bands of 20, 25 and 35 kd. The 30 kd band was found mainly in the extract of the spiral ganglion and the acoustic nerve in the modiolus. The 42 and 58 kd bands were detected in the extract of the spiral ligament and the stria vascularis. The Organ of Corti and the basilar membrane extract gave rise to three bands of 30, 42 and 58 kd. Twenty-eight of the 75 sera from patients with inner ear disease reacted with the 30 and 58 kd bands of the inner ear protein extracts by immunoblotting. Sixteen of these 28 positive sera were then used to probe immunoblots of the brain, kidney, lung, heart and liver extracts. The 58 kd band was also found in protein extracts of the brain, the lung and the liver. This study suggests that the 30 kd antigenic epitope may be mainly related to the acoustic nerve and that the 58 kd antigenic epitope is not cochlear specific.

Animals↗