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At least 37 records · Page 2Linked to original sources
PubMed2003

The effect of hydrogen peroxide applied to the middle ear on inner ear function.

OBJECTIVES/HYPOTHESIS: The objective was to assess the effect of hydrogen peroxide applied to the middle ear on cochlear and vestibular function. STUDY DESIGN: Prospective animal study. METHODS: Sand rats underwent a right-side total labyrinthectomy, and a polyethylene tube was inserted into the left-side middle ear. Following baseline recordings of vestibular evoked potentials in response to linear acceleration stimuli and auditory brainstem response, each experimental animal received five daily applications of hydrogen peroxide into the left-side middle ear. Two control groups received saline and gentamicin, respectively. Subsequently, recordings were repeated and compared with baseline measurements. RESULTS: Saline administration affected neither vestibular evoked potentials nor auditory brainstem response. In contrast, both responses could not be recorded following gentamicin application. After hydrogen peroxide administration, auditory brainstem response could not be recorded in 25% (3 of 12) of the animals, whereas in the remaining nine animals the average auditory brainstem response threshold was significantly elevated by 55 dB (P =.000002). Linear vestibular evoked potentials could not be recorded in 42% (5 of 12) of the animals. CONCLUSION: It appears that topical hydrogen peroxide adversely affects both cochlear and vestibular function of the sand rat. The study demonstrated the effect of a reactive oxygen species on inner ear function and may be useful in the study of mechanisms responsible for this damage and its protection. Clinically, although an animal model was used in the present study, caution should be exercised when large amounts of hydrogen peroxide are applied to a dry, perforated ear.

Administration, Topical↗
PubMed2003

Inner ear decompression sickness and inner ear barotrauma in recreational divers: a long-term follow-up.

OBJECTIVES/HYPOTHESIS: The objectives were to report the authors' experience with the long-term follow-up of patients with diving-related inner ear decompression sickness and inner ear barotrauma and to discuss residual cochlear and vestibular damage in relation to the question of fitness to dive. STUDY DESIGN: Retrospective consecutive case series. METHODS: Eleven recreational divers with inner ear decompression sickness and nine with inner ear barotrauma (IEB) were followed. A complete otoneurological physical examination and laboratory evaluation were carried out. The latter included audiometry, electronystagmography, a rotatory chair test using the sinusoidal harmonic acceleration protocol, and computerized dynamic posturography. RESULTS: Residual cochleovestibular deficits were found in 10 (91%) of the patients with inner ear decompression sickness and 3 (33%) of those with IEB (P <.02, Fisher's Exact test; odds ratio, 20). A significantly shorter follow-up period was required for the inner ear barotrauma group (P <.05, simple t test) because three patients (33%) recovered completely within 1 month of the diving accident. Eight patients had residual vestibular deficits on follow-up, but only one (12.5%) was symptomatic. However, five (56%) of the nine patients who had a cochlear insult, as documented by follow-up audiometry, complained of significant hearing loss and tinnitus. CONCLUSION: Inner ear decompression sickness carries a high risk for residual inner ear damage despite hyperbaric oxygen recompression therapy. A favorable prognosis might be anticipated for inner ear barotrauma. The finding that most patients with residual vestibular deficits were asymptomatic at the time of follow-up emphasizes the need for a complete vestibular evaluation, including specific bedside testing and laboratory examinations, before a return to diving activity may be considered.

Adult↗
PubMed1983

Immunology of the inner ear: response of the inner ear to antigen challenge.

The relationship of the inner ear to host immunity and the immunoresponsiveness of the inner ear to antigen challenge were investigated. A radioimmunoassay was used to quantitate antibody titers to keyhole-limpet hemocyanin generated in the serum, perilymph, and CSF of guinea pigs following systemic or inner ear immunizations. The results of these experiments demonstrate (1) the blood-labyrinth barrier is analogous to the blood-brain barrier with respect to immunoglobulin equilibrium, (2) the inner ear is capable of responding to antigen challenge, and (3) the inner ear is an effective route for systemic immunization.

Animals↗
PubMed2001

COCH5B2 is a target antigen of anti-inner ear antibodies in autoimmune inner ear diseases.

OBJECTIVE: This study was designed to identify the 58-kDa inner ear protein against which the sera of some patients with idiopathic, progressive sensorineural hearing loss or Ménière's disease strongly react. BACKGROUND: We and other groups have previously demonstrated that a 58-kDa protein extracted from guinea pig or bovine inner ear tissue is a target of antibodies in serum samples from some patients with autoimmune inner ear diseases. METHODS: After separation of inner ear proteins by 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis, the bands corresponding to 58 kDa were localized and excised from the gel. The concentrated protein was then digested with trypsin, and the peptide fragments were separated by high-pressure liquid chromatography. Three fractions were subjected to amino acid sequencing by the classic Edman degradation. RESULTS: The sequence of a stretch of 14 amino acids of the first fragment was identical to that of amino acids 526 to 539 of the COCH5B2 protein. The sequences of 11 and 10 amino acids of the second and third fragments, respectively, also were identical to residues 417 to 427 and 396 to 405 of the COCH5B2 protein. These data, together with two-dimensional gel electrophoresis followed by Western blot experiments, confirmed that the 58-kDa inner ear protein is the COCH5B2 protein. DISCUSSION: These findings indicate that the 58-kDa target protein of antibodies in serum samples of patients with autoimmune inner ear diseases is the COCH5B2 protein, a molecule that is highly and specifically expressed in the cochlea and vestibule.

Animals↗
PubMedDate not supplied

Communicatory routes connecting the middle ear, the inner ear and the subarachnoid space via perineural space.

Twenty-one rabbits received injection of Indian ink into the stylomastoid foramen. Observation of the serial sections of their temporal bones revealed Indian ink infiltration into the subarachnoid space, along the facial nerve, the auricular branch of the vagus nerve and the tympanic nerve. Along the acoustic nerve, the infiltration was found as far as the fundus of the internal auditory meatus. In some cases, however, Indian ink reached the subarachnoid space and infiltrated into the scala tympani, scala vestibuli and around the saccule by way of the cochlear aqueduct. These routes are suspected to be a course of spreading infection or tumor cells.

Animals↗
PubMed1997

Interactions between the middle ear and the inner ear: bacterial products.

The round-window membrane (RWM) is extremely thin and is the only soft-tissue barrier between the middle ear and the inner ear. Under inflammatory conditions of the middle ear the various layers of the triple-layered RWM undergo characteristic changes parallel to the changes of the middle-ear mucosa. Several studies report that bacterial products, exo- and endotoxins, from bacteria invading the middle ear may result in profound inflammatory changes in the inner ear, followed by severe damage to the inner-ear function. The present review, in which we summarized experimental and clinical observations, on bacterial products in interactions between the middle and inner ear, focused on: 1. Bacteria and bacterial products in an inflamed middle ear that may influence inner-ear function. 2. RWM structure and RWM permeability under the influence of bacteria and bacterial products. 3. Morphological and functional inner-ear effects of bacterial infection of the middle ear, and the possible mechanisms involved. 4. Future studies to be directed in this field.

Animals↗
PubMed2002

Cochlear function in ears with immunomediated inner ear disorder.

The aim of the present study was to evaluate the performance of ears with inner ear disorder, responsive to immunosuppressive drugs, in advanced tests designed to assess primary cochlear functions (temporal integration, frequency selectivity, cochlear mechanics). The results of this study suggest that immunomediated inner ear disease results, in the acute clinical stage, in the development of endolymphatic hydrops, which increases the stiffness of the vibrating structures within the inner ear and causes dysfunctions of the outer hair cells. Our patients presented with upsloping or flat sensorineural hearing loss, absence of evoked otoacoustic emissions and distortion-product otoacoustic evoked emissions and abnormal temporal integration, frequency selectivity and cochlear mechanics. Following immunosuppressive treatment, hydrops recovered, hearing subsequently returned to normal, the audiometric curve became flat at low-to-middle frequencies and primary cochlear function tended to normalize. This study seems to support the usefulness of testing primary cochlear functions in order to monitor the clinical course of immunomediated inner ear disorders.

Acoustic Impedance Tests↗
PubMed1993

Extraction of inner ear antigens for studies in inner ear autoimmunity.

The search for a diagnostic assay in patients with autoimmune inner ear disease has led to the preparation of antigens from the inner ear, a presumed target in this disorder. In order to standardize the antigen preparations currently being used in the Western blot immunoassay, we have examined several distinct extraction procedures that employ well-known solutions and detergents. Results of this investigation clearly show that antigens of interest (68 kd, 33 to 35 kd, and 32 kd) are optimally extracted with a detergent (0.5% sodium dodecyl sulfate) and that bovine serum albumin, a potential contaminant, can be removed in the water-soluble fractions. Purification of inner ear antigens by these methods will lead to more reproducible results in immunoblotting, as well as a greater opportunity to identify the mechanisms involved in autoimmune inner ear disease.

Antigens↗
PubMed2002

Relationship between three inner ear antigens with different molecular weights and autoimmune inner ear disease.

Crude inner ear antigen (CIEAg) can induce autoimmune inner ear disease (AIED) although it is not known which subcomponent of CIEAg is involved. In this study, we investigated the relationship between 3 purified inner ear antigens (31, 42-45 and 60 kD proteins) and AIED, and determined their distribution in normal guinea pig cochlea. Three groups of guinea pigs were immunized with the three inner ear antigens and one group served as a control. The hearing thresholds, serum IgG level and morphological changes in the inner ear were observed. The expression of the three antigens in the cochlea was detected using immunohistochemical techniques. No obvious changes in hearing thresholds or inner ear morphology were observed between the control and 42-45 kD groups. Animals immunized with the 31 or 60 kD proteins showed a significant increase in hearing thresholds (p < 0.05 vs control), accompanied by morphological changes in the inner ear. The serum IgG level was increased significantly (p < 0.05) in all immunized animals. The 31 kD protein was distributed in the cochlear nerve and spiral ganglion, while the 42-45 and 60 kD proteins were distributed widely, being found in the spiral ganglion, organ of Corti, stria vascularis and spiral ligament. These results suggest that two subcomponents of CIEAg (the 31 and 60 kD proteins) may induce AIED independently, that several inner ear antigens may contribute to the pathogenesis of AIED and that the 31 kD protein is of high tissue specificity and may be used as a marker protein for the clinical diagnosis of AIED.

Animals↗
PubMed1981

Passage of albumin from the middle ear to the inner ear in otitis media in the chinchilla.

A study of the permeability of the middle ear-inner ear interface for macromolecules was carried out in chinchillas with open and obstructed eustachian tubes utilizing tritiated human serum albumin and immunoelectrophoresis. Tritiated albumin was placed in the round window niche area or normal animals and animals in which the eustachian tubes had been obstructed for 24 hours or 14 days. The tritiated albumin was allowed to remain in the middle ear cavity for 24 hours, Samples of middle ear effusion, perilymph, blood and cerebrospinal fluid were collected and measured for radioactivity. Radioactivity was demonstrated in the perilymph. Samples of middle ear effusions and perilymph were also studied by immunoelectrophoresis with goat antihuman albumin. Albumin placed in the round window niche of an experimental animal could be recovered unchanged in the perilymph. The results suggest a pathophysiologic explanation for the association of otitis media and sensorineural hearing loss or endolymphatic hydrops.

Animals↗
PubMed1976

[Formation of the inner ear lymphs. Permeability of inner ear membranes (author's transl)].

1. The endolymphatic system is morphologically a close system. The inner surface of the wall is tightly lined with an epithelium of ectodermal origin. The perilymphatic spaces are enlarged intercellular spaces which are built from the embryonic mesenchyme. 2. The perilymph ist an ultrafiltrate of plasma. There is probably a flow from the cerebrospinal fluid which is constantly renewed. The diffusion in the perilymph is dependent on the concentration and the size of the molecules. The endolymph is mainly a perilymph-filtrate. The "secretory" epithelia (e.g. stria vascularis cells and other tissues) of the endolymphatic system perform an important role to sustain the potassium and sodium concentrations. The ionic concentrations regulate the water movement also the volume of the endolymphatic spaces. They are maintained by anoxy-sensitive pumps. 3. The DC potential within the endolymphatic spaces represents the movement of certain electrical charge through membranes. By applying various inhibitors it is possible to distinguish the pumping mechanisms, and to observe the continuous changes of potassium and sodium concentrations with Na+ specific electrodes and K+ specific electrodes. There are probably three interdependent sources of driving-forces: a. A positively electrogenic K+-pump which is anoxia-sensitive and can be inhibited by Ethacrynic acid. This mechanism is more active in stria cells and less so in utricle and saccule. b. A negatively electrogenic Na+-K+ exchange-pump in all parts of the endolymphatic spaces is inhibited by Ouabain or anoxia. c. The passive diffusion of potassium-ions from endolymph to perilymph results an electro-negative effect.

Animals↗
PubMed1989

Immune response of the endolymphatic sac to horseradish peroxidase: immunologic route from the middle ear to the inner ear.

Twenty guinea pigs were immunized with horseradish peroxidase (HRP) intradermally and challenged with 5 mg of the same antigen in the tympanic bulla. The appearance of immunoglobulin-producing cells (plasma cells) in the inner ear structure was examined immunohistochemically in frozen sections. Four to 10 days following antigen challenge, 5 of the 20 animals showed significantly increased plasma cells in the subepithelial connective tissue of the endolymphatic sac (ES). Those cells showed positive reactions, mainly with IgG followed by IgM. The cells that reacted positively with IgA were few. Some of these plasma cells were considered to contain the specific antibody against HRP. The results indicate the role of the ES as a local immune response region for the inner ear complex, as well as the existence of an immunologic route from the middle ear cavity to the inner ear, particularly to the ES.

Animals↗
PubMed1998

The role of micro-noise trauma in the etiology of aging-related changes in the inner ear.

Eleven chinchillas between 1 and 2.4 years of age had the malleus/incus complex removed from one middle ear and then lived in the Washington University animal facilities for 4 years post-surgery. Each animal had one ear (termed ambient-noise) in which the conductive apparatus was intact; the other ear (termed noise-protected) had a 50-60 dB conductive hearing loss. The background sound level in the animal facility was 59 dBA with periodic brief sounds up to 102 dBA. After the 4-year experimental period, both ears were fixed, embedded in plastic and dissected for microscopic examination as flat preparations. The quantitative and qualitative findings in the noise-protected ears were compared to those in the ambient-noise ears. Both groups of ears sustained losses of sensory and supporting cells throughout the organ of Corti. A variable amount of age pigment was found to have accumulated in the outer hair cells and all supporting cells. In the noise-protected ears, inner hair cell loss ranged from 1.0 to 3.1% and averaged 1.7 +/- 0.8%; outer hair cell loss ranged from 1.8 to 6.4% and averaged 3.6 +/- 1.2%. In the ambient-noise ears, inner hair cell loss ranged from 0.7 to 2.8% and averaged 1.6 +/- 0.7%; outer hair cell loss ranged from 1.3 to 5.4% and averaged 3.6 +/- 1.2%. Within-animal comparison of cell losses in the noise-protected and ambient-noise ears revealed no significant difference between the two groups. It is concluded that long-term exposure to micro-noise does not accelerate the spontaneous loss of sensory cells which occurs with aging. Although not quantified, there was no obvious difference in the amount or cellular distribution of age pigment in the two groups. Thus, it appears that the formation of age pigment in the ear is the result of the cells' basic metabolic processes rather than the wear and tear from sensory transduction.

Aging↗