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At least 973 records · Page 54Linked to original sources
PubMed1983

Report of an isolated mid-frequency hearing loss following inner ear barotrauma.

A case describing an isolated mid-frequency hearing loss as a result of inner ear barotrauma is presented. The onset of symptoms was insidious but progressed to a profound total-range hearing loss in the right ear. This loss resolved rapidly with cessation of diving activity, bed rest, and head elevation, leaving only an isolated 20-dB hearing decrement at 1000 Hz. Since the diver was participating in evaluation of experimental decompression tables, differentiation had to be made between barotrauma and inner ear decompression sickness.

Adult↗
PubMed2001

Sciaenid inner ears: a study in diversity.

Sciaenid fishes (Family Sciaenidae) could potentially serve as models for understanding the relationship between structure and function in the teleost auditory system, as they show a broad range of variation in not only the structure of the ear but also in the relationship between the ear and swim bladder. In this study, scanning electron microscopy (SEM) was used to investigate inner ear ultrastructure of the Atlantic croaker (Micropogonias undulatus), spotted seatrout (Cynoscion nebulosus), kingfish (Menticirrhus americanus) and spot (Leiostomus xanthurus). These species reflect the diversity of otolith and swim bladder morphology in sciaenids. The distribution of different hair cell bundle types, as well as hair cell orientation patterns on the saccular and lagenar maculae of these fishes were similar to one another. The rostral ends of the saccular sensory epithelia (maculae) were highly expanded in a dorsal-ventral direction in the Atlantic croaker and spotted seatrout as compared to the kingfish and spot. Also, ciliary bundles of the saccular maculae contained more stereocilia in the Atlantic croaker and spotted seatrout as compared with kingfish and spot. The shapes of the lagenar maculae were similar in all four species. In the Atlantic croaker and spotted seatrout lagenar maculae, the number of stereocilia per bundle was greater than those for the kingfish and spot. Given that saccular macula shape and numbers of stereocilia per bundle correlate with swim bladder proximity to the ear in the studied species, it is possible that inner ear ultrastructure could be indicative of auditory ability in fishes.

Acoustic Maculae↗
PubMed2001

Inner ear localization of mRNA and protein products of COCH, mutated in the sensorineural deafness and vestibular disorder, DFNA9.

Missense mutations in the COCH gene, which is expressed preferentially at high levels in the inner ear, cause the autosomal dominant sensorineural deafness and vestibular disorder, DFNA9 (OMIM 601369). By in situ hybridization of mouse and human inner ear sections, we find high-level expression of COCH mRNA in the fibrocytes of the spiral limbus and of the spiral ligament in the cochlea, and in the fibrocytes of the connective tissue stroma underlying the sensory epithelium of the crista ampullaris of the semicircular canals. A polyclonal antibody against the human COCH protein product, cochlin, was raised against the N-terminal 135 amino acid residues of cochlin, corresponding to the Limulus factor C-homology (cochFCH) domain; this domain harbors all five known point mutations in DFNA9. On western blots of human fetal cochlear extracts, anti-cochlin reacts with a cochlin band of the predicted full-length size as well as a smaller isoform. Immunohistochemistry performed with anti-cochlin shows staining predominantly in the regions of the fibrocytes of the spiral limbus and of the spiral ligament in mouse and in human fetal and adult tissue sections. These sites correspond to those areas that express COCH mRNA as determined by in situ hybridization, and to the regions of the inner ear which show histological abnormalities in DFNA9. The fibrocytes expressing mRNA and protein products of COCH are the very cell types which are either absent or markedly reduced and replaced by eosinophilic acellular material in temporal bone sections of individuals affected with DFNA9.

Adult↗
PubMed2003

Cell adhesion molecules during inner ear and hair cell development, including notch and its ligands.

Cellular adhesion plays a key role in a number of unique developmental events, including proliferation, cell fate, morphogenesis, neurite outgrowth, fasciculation, and synaptogensis. The number of families of molecules that can mediate cell adhesion and the number of members of each of those families has continued to increase over time. Moreover, the potential for the formation of different pairs of heterodimers with different binding specificities, and for both homo- and hetero-dimeric interactions suggest that a vast number of specific signaling events can be mediated through the expression of different combinations of adhesion factors at different developmental time points. By comparison with the number of known adhesion molecules and their potential effects, our understanding of the role of adhesion in ear development is extremely limited. The patterns of expression for some adhesion molecules have been determined for some aspects of inner ear development. Similarly, with a few exceptions, functional data to indicate the roles of these adhesion molecules are also lacking. However, a consideration of even the limited existing data must lead to the conclusion that adhesion molecules play key roles in all aspects of the development of the auditory system. Unique expression domains for different groups of adhesion molecules within the developing otocyst and ear strongly suggest a role in the determination of different cellular domains. Similarly, the specific expression of adhesion molecules on developing neurites and their target hair cells, suggests a key role for adhesion in the establishment of neuronal connections and possible the development of tonotopy. Finally, the recent demonstration that Cdh23 and Pcdh15 play specific roles in the formation of the hair cell stereociliary bundle provides compelling evidence for the importance of adhesion molecules in the development of stereocilia. With the imminent completion of the mouse genome, it seems likely that the number of adhesion molecules can soon be fixed and that it will then be possible to generate a more comprehensive map of expression of these molecules within the developing inner ear. At the same time, the generation of new transgenic and molecular technologies promises to provide researchers with new tools to examine the specific effects of different adhesion molecules during inner ear development.

Animals↗
PubMed1999

Development of inner ear (cochlear and vestibular) function in the fetus-neonate.

The development of function in the various receptors in the inner ear was studied in the neonatal rat, which is altricious with respect to hearing, using short latency evoked potentials, both auditory (ABR) and vestibular (VsEP). It was found that VsEPs could be recorded from all the vestibular end-organs by post natal day (PND) 8, whilst ABR could only be recorded from all animals on PND 14, showing the earlier onset of vestibular function in the inner ear. These results are discussed with relation to onset of inner ear function in the human fetus.

Animals↗
PubMed2004

Trophic effects of insulin-like growth factor-I (IGF-I) in the inner ear.

Insulin-like growth factors (IGFs) have a pivotal role during nervous system development and in its functional maintenance. IGF-I and its high affinity receptor (IGF1R) are expressed in the developing inner ear and in the postnatal cochlear and vestibular ganglia. We recently showed that trophic support by IGF-I is essential for the early neurogenesis of the chick cochleovestibular ganglion (CVG). In the chicken embryo otic vesicle, IGF-I regulates developmental death dynamics by regulating the activity and/or levels of key intracellular molecules, including lipid and protein kinases such as ceramide kinase, Akt and Jun N-terminal kinase (JNK). Mice lacking IGF-I lose many auditory neurons and present increased auditory thresholds at early postnatal ages. Neuronal loss associated to IGF-I deficiency is caused by apoptosis of the auditory neurons, which presented abnormally increased levels of activated caspase-3. It is worth noting that in man, homozygous deletion of the IGF-1 gene causes sensory-neural deafness. IGF-I is thus necessary for normal development and maintenance of the inner ear. The trophic actions of IGF-I in the inner ear suggest that this factor may have therapeutic potential for the treatment of hearing loss.

Animals↗
PubMed2006

Restricted expression of Fgf16 within the developing chick inner ear.

Fibroblast growth factor (FGF) signaling is required for otic placode induction and patterning of the developing inner ear. We have cloned the chick ortholog of Fgf16 and analyzed its expression pattern in the early chick embryo. Expression is restricted to the otic placode and developing inner ear through all the stages examined. By the closed otocyst stage, expression has resolved to anterior and posterior domains that partially overlap with those of bone morphogenetic protein 4 (Bmp4), a marker of the developing sensory patches, the cristae of the anterior and posterior semicircular canals. Platelet-derived growth factor alpha (PDGFA), another growth factor with restricted otic expression, also overlaps with Fgf16 expression. The restricted expression pattern of Fgf16 suggests a role for FGF signaling in the patterning of the sensory cristae, together with BMP signaling.

Amino Acid Sequence↗
PubMed2007

A potential portal flow in the inner ear.

OBJECTIVES/HYPOTHESIS: The aim of the present study was to visualize the flow direction of blood in the extraosseous part of the vein of the vestibular aqueduct (VVA) and to explore the effect of an induced obstruction in the distal part of the VVA before it merges with the sigmoid sinus. The endolymphatic sac has been implicated as a potential endocrine gland, which venules drain to the VVA. A reversal of the direction of flow in the VVA toward the inner ear could, through vestibular arteriovenous anastomosis, cause portal circulation in the inner ear. STUDY DESIGN: The authors conducted an experimental animal study using in vivo fluorescence microscopy. RESULTS: Obstructing the distal part of the VVA just before it empties into the sigmoid sinus immediately reverses the flow of blood in the VVA toward the inner ear. CONCLUSIONS: After an obstruction of the VVA, the drained venous blood from the endolymphatic sac may enter a portal circulation in the inner ear, which could cause disturbances in the endolymph homeostasis and potentially symptoms as seen in Meniere disease.

Animals↗
PubMed2002

A compendium of mouse knockouts with inner ear defects.

Genetically engineered strains of mice, modified by gene targeting (knockouts), are increasingly being employed as alternative effective research tools in elucidating the genetic basis of human deafness. An impressive array of auditory and vestibular mouse knockouts is already available as a valuable resource for studying the ontogenesis, morphogenesis and function of the mammalian inner ear. This article provides a current catalog of mouse knockouts with inner ear morphogenetic malformations and hearing or balance deficits resulting from ablation of genes that are regionally expressed in the inner ear and/or within surrounding tissues, such as the hindbrain, neural crest and mesenchyme.

Animals↗
PubMed1997

Inner ear perfusion and the role of round window patency.

OBJECTIVE: The goal of this investigation was to evaluate the degree of round window membrane obstruction in the native state. The implications for the perfusion of the inner ear via the intratympanic instillation of medications are addressed. STUDY DESIGN: This was a retrospective chart review and a prospective intraoperative observation in the setting of an outpatient office. PATIENTS: The study population was composed of 41 patients who were undergoing middle ear endoscopy before perfusion of the inner ear with medication for the treatment of Meniere's disease, sudden sensorineural hearing loss, or tinnitus. INTERVENTION: Office-based laser-assisted tympanostomy and middle ear endoscopy was carried out in each case. Lysis of adhesions overlying the round window membrane was undertaken when the underlying round window membrane could not be visualized. MAIN OUTCOME MEASURES: Evaluation of the round window niche with regard to accessibility of the round window membrane was recorded for each patient studied. RESULTS: Of the 41 cases examined, 29 of the round windows were judged to be unobstructed, 7 were obstructed partially, and 5 were obstructed completely. CONCLUSION: A significant rate of round window obstruction exists among patients who have no history of manipulation to this area. Although, intuitively, we would expect prior middle ear surgery to increase the likelihood of obstruction, this is not uniformly the outcome. If intratympanic instillation of a medication is contemplated for the treatment of an inner ear disorder, considerations for the evaluation of the round window should be made to enhance adequate diffusion into the perilymph.

Aged↗
PubMed1988

The presence and localization of receptors for atrial natriuretic peptide in the inner ear of the guinea pig.

Atrial natriuretic peptide (ANP) is a cardiac hormone known to mediate increased capillary permeability, vasodilation, and natriuresis. Since specific receptors for ANP exist in both the eye and brain, possibly playing a role in ocular and cerebrospinal fluid regulation, we postulated that ANP might also be involved in inner ear fluid dynamics. Autoradiography was used to evaluate whether and where ANP receptors are present in the inner ear. Frozen sections of the cochlea and vestibular organ from guinea pigs (n = 18) were incubated in either 125J-ANP alone or together with an excess of unlabeled ANP (as control). ANP receptors were demonstrated in the stria vascularis of the cochlea and in the secretory epithelium of the ampulla and the utriculus, but not in the region of the sensory cells. These results indicate that (1) specific ANP receptors are present in the inner ear, and (2) their local distribution is congruent with those parts thought to regulate labyrinthine fluid composition and volume. We speculate that ANP contributes to the homeostasis of the inner ear fluids and may even play a role in the pathophysiology of Menière's disease.

Animals↗
PubMed2000

Expression of vascular cell adhesion molecule-1, alpha4-integrin and L-selectin during inner ear immunity reaction.

The expression of vascular cell adhesion molecule-1 (VCAM-1), alpha4-integrin and L-selectin was dynamically observed using an immunohistochemical approach during labyrinthitis induced by inoculation of keyhole limpet hemocyanin into the scala tympani of animals that had been systemically sensitized to it. At the same time, we used ELISA to monitor interleukin-1(IL-1) in the peripheral blood of these animals. The expression of alpha4-integrin and L-selectin on the surface of leukocytes in peripheral blood was examined by flow cytometry. VCAM-1 was found on the endothelial surface of the spiral modiolar vein (SMV) and its collecting venules (CV) at 24 h post-challenge; the VCAM-1 level reached a maximum on day 2, which was maintained until 1 week post-challenge, and then declined gradually. Alpha4-integrin was found on the surface of leukocytes, mainly monocytes and lymphocytes, that had infiltrated the SMV, CV, cochlear nerve and perilymph by 24 h post-challenge; the alpha4-integrin level reached a maximum on day 2 and then decreased rapidly. At 1 week post-challenge, no significant expression of alpha4-integrin was seen. Expression of alpha4-integrin and L-selectin was also observed on leukocytes in peripheral blood. No L-selectin was observed on the surface of leukocytes during inner ear inflammation. The expression of L-selectin on the surface of leukocytes in the peripheral blood appeared to be downregulated during inflammation. The concentrations of IL-1 in the peripheral blood increased commensurately during inner ear inflammation. These results further elucidate the role of adhesion molecules during inner ear immune responses. The increased expression of VCAM-1 on SMV and CV was correlated with the concentration of IL-1 in peripheral blood during inner ear inflammation.

Animals↗
PubMed2002

Localization of glucocorticoid receptors in the murine inner ear.

We performed an immunohistochemical investigation of the distribution of glucocorticoid receptors (GRs) in the murine inner ear and found that GRs were expressed extensively, but with various degrees of immunoreactivity in different regions. We observed the strongest GR expression in the type III fibrocytes of the spiral ligament. Although the immunoreactivity of the cochlear hair cells and of the vestibular sensory epithelia was weak, the neighboring cochlear supporting cells and the subepithelial regions of the vestibular sensory epithelia were immunostained. Staining for GRs was also positive in the spiral ganglia and vestibular ganglia, as well as in the endolymphatic sac. The role of GRs in the inner ear is discussed.

Animals↗
PubMed1991

Atrial natriuretic peptide-like immunoreactive cells in the guinea pig inner ear.

Using specific antibodies against cardiodilatin/atrial natriuretic peptide (CDD/ANP) in a conventional immuno-histochemical method (PAP) we located ANP/CDD-like immuno-reactive cells related to the secretory area, to the sensory and to the neuronal area in the compartments of the inner ear (cochlea, utricle/ampulla, and endolymphatic sac). Immunoreactive cells were unevenly distributed in the different compartments as well as within the cochlear space. Our findings suggest that ANP/CDD may play a role in the local control of fluid and electrolyte homeostasis of the inner ear. ANP/CDD-binding sites and ANP/CDD-like immunoreactivity in the inner ear may also indicate that the peptide has an additional paracrine and/or autocrine function in the organ.

Animals↗
PubMed2000

Inner ear abnormalities in Kabuki make-up syndrome: report of three cases.

Three patients, a female and two males, 28, 15, and 14 years of age, with Kabuki make-up syndrome (KMS) were studied for middle and inner ear abnormalities by using CT scanning of the petrous bones. All three patients had bilateral dysplasia of the inner ear, i.e., hypodysplasia of the cochlea, vestibule, and semicircular canals (so-called Mondini dysplasia), whereas their middle ears had no abnormalities. Audiometry demonstrated a sharp decrease in hearing of the high tone range, bilateral in one and unilateral in another, while the third patient was noncooperative. In view of these findings, it would be advisable to study each individual with KMS and hearing impairment for possible inner ear abnormalities.

Abnormalities, Multiple↗
PubMed2002

Clinical and experimental studies of autoimmune inner ear disease.

Otolaryngologists have long sought to identify causes of sensorineural hearing loss that could be reversed by medical treatment. An increasing amount of clinical and experimental evidence indicates that this postulated entity is related to autoimmune inner ear disease. Because of the lack of well-defined detection methods for identifying autoimmune processes within the human inner ear and the fact that it is one of the few organs of the body not amenable to diagnostic biopsy there has been great interest in developing animal models that mimic clinical entities. Different models will be presented in this paper. The results of these studies should provide sufficient evidence to establish a clear position in mainstream immunology for the entity of autoimmune inner ear disease.

Animals↗