Deformities of the external ear associated with middle ear, inner ear, or distant malformations.
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Abnormalities, Multiple↗
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Inner ear disturbances following inoculation of endotoxin into the middle ear.
Inner ear function was assessed by a frequency-specific (+/-100 Hz) auditory brainstem response (ABR) technique after a single instillation of a suspension of purified E. coli lipopolysaccharide in sterile water into the round window (RW) niche in rats. Instillation of endotoxin caused a transient concentration and tonotopically dependent dysfunction of the inner ear. The largest threshold impairment occurred in the high-frequency region anatomically located close to the RW. At 31.5 kHz the threshold impairment persisted throughout the study. Morphologic damage to the inner ear was not detected at the light microscopic level when using serial sections from decalcified specimens. Our study supports the clinical hypothesis that remnants of non-viable bacteria such as endotoxins, when trapped in the middle ear, can promote middle ear effusion and dysfunction of the inner ear.
Animals↗
Characteristic ionic composition of endolymph is maintained in cultured inner ear.
Inner ear anlagen from mouse were explanted on the 16th gestational day (gd) and cultured for 5 days, i.e. corresponding to the time of birth. By using energy dispersive X-ray technique an elemental composition characteristic for endolymph was found within the membranous labyrinth of the explants. The sodium to potassium ratio in the endolymphatic space of the cultured inner ears corresponded to endolymph of the 16th gd fetus in vivo. There was no difference in the endolymph compartment between the cochlear and vestibular halves of the in vitro specimens. Differences in Na to K ratio between endolymph of the inner ears and the surrounding medium were statistically significant. Thus, endolymph-regulating mechanisms are active also under organ culture conditions, although not fully optimal.
Animals↗
Survey of interactions between middle ear and inner ear.
Diseases with interaction between the middle ear and inner ear include 1) congenital anomalies, 2) trauma, 3) infection/inflammation, 4) tumors, 5) granulomas, 6) ototoxic eardrops, 7) cochlear implants, 8) otosclerosis, 9) Meniere's disease-decompensated, and Meniere's disease with perilymphatic fistula, and 10) perilymphatic hypertension. Clinical and pathological characteristics are briefly categorized in this survey. The clinical utility of exploratory tympanotomy in diagnosis and treatment of middle ear pathology and middle ear/inner ear interactions is commented upon.
Ear↗
[Binding of serum immunoglobulins to human inner ear tissue in inner ear hearing loss: methodologic limits].
The immunopathological processes possibly involved in cryptogenic sensorineural hearing loss were investigated. In a pilot study the sera from 66 patients were tested by the indirect immunofluorescence technique for immunoglobulins which bind to normal human inner ear tissue. The reaction was positive in two thirds of all patients with sudden hearing loss, especially bilateral. This was mostly for IgG, and to the organ of Corti. Others have found that Corti's organ showed marked degenerative changes in cases of sudden hearing loss, examined by histology. The reaction was positive in half of the patients with progressive sensorineural hearing loss. It was noticeable that positive reactions for IgA were twice as frequent in sera of patients with progressive hearing loss than in those with sudden deafness. In a control study, the sera of ten patients were tested in parallel by the same method on histological sections of inner ears taken from four individuals. Similar results were found for the sera of two patients only. The sera of the remaining eight patients revealed very inconsistent reaction patterns. These preliminary results may indicate that temporary or permanent humoral (auto) immune mechanisms could have occurred in certain inner ear diseases. So far however reliable diagnostic methods have not been established, and not enough patients have been followed up.
Adolescent↗
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↗
[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↗
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↗
Effect of human fibrin adhesive on the ear. An electrophysiological study of auditory function in the guinea pig correlated to light and electron microscopy of middle ear mucosa and inner ear structures.
The effect of human fibrin adhesive applied to the middle ear has been studied in guinea pig. Auditory function was measured using acoustically evoked brainstem responses. Middle and inner ear structures were studied with light, transmission and scanning electron microscopy. A transitory conductive hearing loss was observed, but after 8 weeks the auditory function appeared normal. Microscopy of the middle and inner ear failed to show any tissue damage.
Animals↗
Symposium: new data for noise standards. 3. Organ culture of the mammalian inner ear: a tool to study inner ear deafness.
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Animals↗
[Possibilities of pharmacological influencing of the inner ear--pharmacokinetic studies on the inner ear].
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Aminohippuric Acids↗
Role of middle ear endotoxin in inner ear inflammatory response and hydrops: long-term study.
The permeability of the round window membrane for Salmonella typhimurium-derived endotoxin was examined with use of a total of 33 chinchillas. One milligram of each endotoxin was instilled into the tympanic cavities via the superior bullae. The endotoxin activities in middle ear effusions (MEEs), perilymph, and sera were determined by limulus amebocyte lysate assay. Endotoxin was detected in perilymph on the inoculated side by 12 hours after endotoxin instillation and persisted for up to 3 weeks. Endotoxin level peaked at 24 to 48 hours postinstillation, and it steadily declined afterward. This result suggests that the maximum penetration occurred during the active inflammatory stage. Histologic evidence demonstrated remarkable pathologic changes in the inner ear, including bleeding and inflammatory cell recruitment, mostly in the perilymphatic spaces (eg, scalae tympani, scalae vestibuli, spiral ligament), strial swelling, and sensory cell degeneration. This result suggests that endotoxin present in the middle ear can permeate the round window membrane, causing inner ear tissue damage in this animal model.
Animals↗
Inner ear barotrauma.
Inner ear barotrauma was observed by compressing or decompressing guinea pigs. The barotrauma in compression was greatly influenced by auditory tube function, and, in the animals deprived of this function, we could observe far more severe damage of inner ear hair cells and far more frequent round window rupture than in animals not thus deprived. Barotrauma in decompression was brought about in guinea pigs not deprived of auditory tube function with a decompression speed of 0.1 kg/cm2/sec, which is so severe that even a healthy auditory tube could not endure it. It can be said that the middle and inner ear are more apt to be damaged in decompression than in compression.
Animals↗
[Inner ear hearing loss--predisposing factor in acute disorders of inner ear function (sudden deafness and vestibular loss)?].
49% of 111 patients with sudden hearing loss had pre-existing inner ear damage to a greater extent than would be expected in a population of the same age. The same age-independent hearing loss of inner ear type was seen in 44% of 72 patients with a sudden unilateral isolated vestibular loss. The accumulated occurrence of diseases of the cardial-vascular system, metabolism, and cervical spine is suggested as the reason for the greater extent of inner ear damage with respect of age and the acute disorders in this area. The high proportion of a pre-existing noise deafness in patients (in 38% of men) with sudden hearing loss suggests an increased vulnerability of the inner ear in pre-existing hearing loss.
Adult↗
Histopathology of chloroform-induced inner ear damage.
Inner ear function loss was caused in guinea pigs and rats by injecting chloroform into the middle ear. After symptoms for cochlear and vestibular deficit had been registered, the animals were permitted to survive for one day to five months. Ear histopathology was then studied in celloidin sections. In both species, hair cells and afferent nerve fibers were intact at all survival times. The acute stage of functional loss in guinea pigs was associated with inner ears of normal histological appearance. Within days after chloroform injection a severe otitis media developed which led to fibrous occlusion of the round window and eventually to new bone growth in the middle ear space around the otic capsule. A secondary labyrinthitis was also observed, resulting in endolymphatic hydrops at longer survival times. Different histopathological changes were seen in rats. The tectorial membrane appeared swollen in all cases, the swelling being more severe in more apical turns at longer survival times. It is concluded that only secondary sequela of the initial functional insult can be detected by standard light microscopic histopathology. Chloroform does not cause a chemical labyrinthectomy as previously assumed, although it is severely ototoxic.
Animals↗
Pressure transmission properties from the externa ear canal to the inner ear. An experimental study using guinea pigs.
The inner ear pressure (PIE) in response to pressure changes in the external ear canal was measured in guinea pigs while alternatively opening and closing the perforation of the otic bulla. When the bulla was opened, only a transient degree of applied pressure was transmitted to the inner ear and the amplitude of the PIE was smaller than that of the corresponding PIE when the bulla was closed. This was because the applied pressure was exclusively transmitted to the inner ear via the ossicular chain. When the otic bulla was closed, the pressure was transmitted not only via the ossicular chain but also via the round window (RW) through the middle ear cavity. When the bulla was closed, the amplitude of PIE was larger by a positive pressure load than by the corresponding negative one. The amplitude of PIE showed a linear relationship to ear canal pressure of at least within the +/- 200 mmH2O range, as long as pressure was slowly applied to the ear canal. When the loading pressure was abruptly changed, a bouncing response, possibly reflecting elasticity of the RW, was evoked, which diminished or disappeared when the round window was artificially ruptured.
Acoustic Impedance Tests↗
Damage to the middle ear and the inner ear in underwater divers.
Postmortem human tissue from recently deceased divers was processed histologically to assess any inner and middle ear damage that could have resulted from the effects of pressure during diving. The following new findings are particularly noteworthy. In one diver, ascent while breath holding resulted in the rupture of the ear drum and blood in the middle ear, in addition to pulmonary barotrauma. In a second diver, following inner ear decompression sickness, new bone growth, similar to that described earlier in experimental studies with the squirrel monkey, was observed in the arms of one of the semicircular canals. These observations are further confirmation that otologic disorders can be a serious threat to divers.
Barotrauma↗
Inner ear fine structures of the hamster in frozen sections used for immunohistochemical assays for inner ear diseases.
Frozen sections of the inner ear of the hamster enable detailed investigations of the fine structures in immunofluorescence assays. At high magnification single mitochondria can be identified by their reactions with an antiserum containing antibodies against mitochondria. In the positive reaction with an antiserum against nuclei, the typical green fluorescence is restricted to the nuclei, which are mostly separated by the surrounding cytoplasm. The method of immunohistochemical assay using frozen sections from the non-decalcified inner ear is very time-consuming and cannot be recommended for the routine diagnosis of inner ear diseases, although it may be useful in research and for studying critical clinical cases.
Animals↗