Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ear, Middle”

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 127 records · Page 7Linked to original sources
PubMedDate not supplied

Gas absorption in the middle ear.

The middle ear (ME) pressure of alert and anesthetized rhesus monkeys was monitored by serial tympanograms in order to determine the gas absorption process in the ME cavity. During the four-hour observation period the ME pressure showed small, random fluctuations around zero pressure in the alert animals, whereas in the anesthetized animals, following an initial positive pressure phase, the ME pressure reached a plateau at an average pressure of -60 mm H2O. The ME gas composition was changed by air or oxygen gas politzerization in anesthetized animals to determine the effect of different initial gas compositions on the rate of absorption of the gas and on the magnitude of ME pressure. Politzerization with air and with oxygen gas resulted in average maximum ME pressures of -400 and -730 mm H2O, respectively. The experimental evidence suggested that the physiological composition of ME gases is nearly that of the surrounding environment and that the rate of gas absorption is low. When the gas composition of the ME is changed, the ME pressure decreases considerably. Based on these findings, a possible mechanism for the development of negative ME pressure is proposed.

Absorption↗
PubMed1984

[Diagnosis of middle ear tuberculosis].

Middle ear tuberculosis is underdiagnosed. Clinical suspicion requires extensive diagnostic and therapeutic procedures. Due to a high degree of error in bacteriological and histological examination they must often be repeated. Indications for tentative diagnosis are given.

Adult↗
PubMed1997

Pharmacokinetics of antibiotics in the middle ear.

The middle ear mucosa is described as a non-specialized site where drug substances diffuse passively. However, precise pharmacokinetic studies on antibiotic penetration into middle ear effusion (MEE) are difficult to conduct in humans because of ethical and methodological problems: (1) studies must involve the population in which acute otitis media (AOM) is most frequent (i.e. in children from 3 months to 3 years of age); (2) studies are commonly performed during surgery for chronic otitis media with effusion, whereas drug penetration into MEE is higher during AOM; (3) kinetics are deduced from data per individual obtained in groups with marked interindividual variations. Furthermore, the results of different studies are difficult to compare because of differences in protocols, antibiotic assay methods and interpretation. Clinical studies have nonetheless shown the poorly predictive nature of serum concentrations, given the large differences in drug delivery to the MEE among antibiotic classes, among members of the same class, and among individuals receiving a given antibiotic. Experimental studies can help to narrow the gap between in vitro and clinical data, as the more precise pharmacokinetic data they yield can throw light on the link between drug/host/pathogen factors and bacteriologic efficacy.

Journal Article↗
PubMed1981

Office myringotomy for acute otitis media: its value in preventing middle ear effusion.

Middle ear effusion (MEE) as a residual of treated acute otitis media was found in 49% of 776 children studied. No antibiotic singly or in combination, demonstrated superiority in reducing the incidence of MEE. Simple myringotomy, as a therapeutic modality in 415 children who presented with an acutely bulging painful eardrum, did not facilitate adequate drainage as 51% of such children, treated with simple myringotomy in addition to antibiotics, had MEE detected 10 days later. The incidence of MEE also occurred independently of the middle ear pathogen. Within six weeks, spontaneous resolution of the effusion occurred in 85% of the 382 children with MEE that was detected 10 days after acute otitis media.

Acute Disease↗
PubMed2003

Canal wall down tympanoplasty with canal reconstruction for middle-ear cholesteatoma: post-operative hearing, cholesteatoma recurrence, and status of re-aeration of reconstructed middle-ear cavity.

The post-operative outcome of hearing, the reconstructed external auditory canal, and the state of the reconstructed middle-ear cavity after canal wall down tympanoplasty with canal and attico-antrum reconstruction was studied in 103 ears with middle-ear cholesteatoma. The reconstructed mastoid cavity was re-aerated in 36.5 per cent of the cases, which was significantly lower than for the epitympanum (63.5 per cent) and tympanic cavity (82.4 per cent). Tympanoplasty was successful in terms of hearing results in 68.9 per cent of all subjects and in 75.4 per cent of the ears having a re-aerated tympanic cavity, which was significantly better than the 38.5 per cent for ears in which the tympanic cavity was not re-aerated. The findings of recurrent cholesteatoma, tympanic atelectasis, and tympanic effusion were observed with significantly (p<0.03) high incidence in ears with no re-aerated space in their reconstructed mastoid cavities. It was revealed that the post-operative outcome of this surgical technique was significantly related to the state of re-aeration of the reconstructed middle-ear cavity.

Adolescent↗
PubMed1990

[Tissue culture of middle ear epithelium of the guinea pig--differences of the cellular growth activity in the middle ear cavity using collagen gel culture method].

Primary tissue culture system from the middle ear and the tracheal epithelium of the guinea pig was established using collagen gel method. The cultured epithelium was studied by phase-contrast microscopy, light and scanning electron microscopy. The outgrowth area of the epithelium was quantitatively measured for period of up to ten days. In the middle ear cavity, the mucosal explants were sampled from various sites in order to compare their differential and proliferative activities. The mucosal explants attached on collagen substrates were composed of ciliated, non-ciliated, goblet and basal cells. This basic structure was similar to the natural middle ear epithelium. The ciliated cells showed well organized cilia. Most of the outgrowth cells devoid of fibroblastic cells in the monolayer were polygonal shaped with numerous microvilli. The morphology of the outgrowth cells changed from columnar or cuboidal to squamous shapes in the area away from the explants. There was a correlation between the distribution of the ciliated cells in the outgrowths and these in the explants. The explants with columnar or cuboidal ciliated epithelia sampled from the opening of the eustachian tube or its neighborhood formed more than eightfold outgrowth sheets in vitro. This is comparable to tracheal epithelia. On the other hand, the explants with simple squamous epithelia sampled from the area distal to the eustachian tube showed about fourfold proliferative activity. We concluded that this culture system would be useful for the study of cellular multiplication and differentiation mechanisms of the respiratory tract epithelium.

Animals↗
PubMed1987

Hyaluronan in the middle ear of the rat. The normal distribution of hyaluronan and the clearance of exogenously administered hyaluronan from the middle ear.

The content of hyaluronan (HA), a common connective tissue component, was determined in well defined areas of the rat middle ear. The HA concentration in the pars flaccida of the tympanic membrane was considerably greater than in the pars tensa and areas on the medial wall of the middle ear cavity. The fate of exogenous HA introduced into the middle ear was also studied in rats. Tritium-labelled HA disappeared through the Eustachian tube (ET) and was followed by analysis of the nasopharyngeal secretion. The radioactivity in the secretion reached a peak at 3 h and decreased to almost zero within 12 h, indicating that most of the HA was removed. By autoradiography and direct analysis of the HA concentration and molecular weight distribution the fate of HA after obstruction of the ET was followed. Radioactive HA was confined to the middle ear and no uptake into surrounding tissues could be traced by autoradiography 4 days after application. The amount of HA that could be recovered from the middle ear was constant for up to 6 days. Analysis of the molecular weight distribution of the deposited HA indicated only slow degradation during these 6 days.

Animals↗
PubMed1997

Histomorphometric study of the normal middle ear mucosa. Preliminary results supporting the gas-exchange function in the postero-superior part of the middle ear cleft.

This study concerns the distance between the centre of gravity of blood vessels and the basement membrane of the middle ear cleft mucosa. The measurements were performed perpendicular to the long axis of the cross-section of the vessels, and revealed a significant difference between two regions of the middle ear cleft. At the level of the postero-superior part (epitympanum, aditus ad antrum, mastoid antrum and highest part of the mastoid air cells system), the distance between the blood vessels and the basement membrane of the mucosa was statistically shorter than in the antero-inferior part of the middle ear cleft. This indicates a privileged function of gaseous exchange of the postero-superior part of the middle ear cleft and may divide the middle ear cleft into different functional parts.

Aged↗
PubMed1999

[Middle ear physiology].

The middle ear forms part of the sound transformer mechanism, together with the outer ear and the conducting system of the inner ear. An intermediate sensory organ, sensitive to acoustic vibration, and linked to the inner ear, the middle ear made its appearance during the period of adaptation of marine creatures to a terrestrial habitat; its presence is therefore a phylogenetic requirement. It is classical to ascribe three functions to the middle ear: the transmission of acoustic vibrations from the tympanic membrane to the cochlea, impedance matching between the air in the external auditary meatus and the labyrinthine fluids, and protection of the inner ear by means of the acoustic reflex. If the classical mechanical explanation has been able to explain its function, the conceptualization of its physiology in terms of energy allows an even better understanding, as well as providing and explanation for the paradoxes which arise in clinical practice when the classical model is used.

Ear, Middle↗
PubMedDate not supplied

Distribution of HRP in the inner ear after injection into the middle ear cavity.

The distribution patterns of horseradish peroxidase (HRP) reaction products in the inner ears of guinea pigs were studied after injections into the middle ear cavities and perilymphatic and subarachnoid spaces. The normal round window membrane resisted HRP penetration from the middle ear side, but when it became pathological after repeated applications, its permeability increased. HRP deposits were found in the cochlear and vestibular sensory cells and in the lumen of the endolymphatic sac. HRP reaction products were minimal at the cochlear apex even after long survival times, suggesting that perilymph flow, if it exists, is rather weak toward this direction. Whereas the stria vascularis is impermeable to HRP, the vestibular dark cells were accessible; thus, the metabolic activity of the dark cells can be more readily controlled by drug applications through the middle ear cavity. The finding of HRP deposits on the scala vestibuli surface of Reissner's membrane and the absence of HRP in the upper portion of the spiral ligament at the basal turn suggests that the oval window is a secondary route of passage for these particles from the middle ear cavity to the inner ear. In order to determine the route of HRP into the endolymphatic sac from the middle ear cavity or scala tympani, the cochlear and/or vestibular aqueducts were obliterated singly or together. The route of HRP was determined to be the vestibular aqueduct. HRP is believed to enter the sac lumen through Reissner's and saccular membranes and the sac epithelium. Drugs and other large molecular substances instilled in or gaining access to the middle ear cavity may reach the endolymphatic sac causing its functional alteration.

Animals↗
PubMed1984

Ear drum mobility and middle ear volume measured with tympanometry.

Tympanometry was evaluated as a measure of the volume of the air-containing space of the middle ear cleft as well as of tympanic membrane displacement in persons with intact tympanic membranes. Static compliance reduced with compliance of ear canal volume at -400 mm H2O, was determined with 0.22 kHz probe tone frequency. Further the difference in compliance obtained at +/- 400 mm H2O was regarded as a measure of ear drum mobility. The volume of the middle ear cleft including the mastoid air cell system was measured indirectly by X-ray of the ear in a lateral projection. No relation was found to exist between static compliance and mastoid air cell area measured on the X-ray film. Nor was there any relation found between ear drum mobility measured with tympanometry and size of the mastoid air cell system.

Acoustic Impedance Tests↗
PubMed2001

Mass loading on the ossicles and middle ear function.

The middle ear as a levered vibrating system for sound transmission from the external to the inner ear is affected by changes in ossicular chain mass. Mass loading of the ossicles may impair ossicular dynamics and sound transmission to the inner ear. It is incumbent on otologic surgeons and researchers of middle ear mechanics to consider the mass loading effect on middle ear function in clinical and physiological applications. The residual hearing and frequency response can change after surgery or implantation of middle ear prostheses. We conducted experiments on mass loading effects on the middle ear transfer functions by using laser Doppler interferometry and a human temporal bone model. Two implant mass loading conditions were tested on 17 fresh or fresh-frozen temporal bones and compared with the unloaded condition for the frequencies 250 to 8,000 Hz. The results show that the linearity of the middle ear function did not change, although displacement of the stapes footplate decreased after the increased masses were placed on the incudostapedial joint. The greater the mass of the implant, the less displacement was measured at the stapes footplate. We conclude that there is a quantitative limit to increased mass on the ossicular chain above which the mass will remarkably impair hearing thresholds.

Adult↗
PubMed2005

Effects of age and size in the ears of gekkonomorph lizards: middle-ear morphology with evolutionary implications.

The function of the ear depends in part on its absolute size and internal proportions. Thus, in both young individuals and small species, the middle ear is expected to be allometrically enlarged despite its smaller absolute size. Here we aim to compare the ontogenetic allometry of relevant middle-ear structures as observed within gecko (gekkonomorph lizards) species, with the evolutionary allometry observed interspecifically. These observations also provide middle-ear data for future evaluation of variation in auditory sensitivity. The material comprised 84 museum specimens of geckos, representing nine species of three gekkonomorph subfamilies. The results of dissections and measurements show that different reports notwithstanding, the middle-ear ossicular chain is indeed structured as described for geckos by Werner and Wever. Some sexual dimorphism is indicated, but this requires further study. During postnatal ontogeny, the allometric growth in the ratio of the columellar footplate area to body length differed between the intraspecific and interspecific levels, hence species differences in the middle ear do not merely result from animal size. The ratio of the tympanic membrane area to the columellar footplate area increased during ontogeny. In this, geckos resemble birds and probably also mammals. Similarly, when the comparison was among adults representing different species, the ratio of the tympanic membrane area to the columellar footplate area increased with body size. In this, however, the geckos differed from birds and mammals, in which this ratio varied taxonomically, irrespective of body size. It would thus seem that middle-ear proportions have evolved among geckos to produce small interspecific differences, but among amniote tetrapods they have evolved according to different principles in the classes reptiles, birds, and mammals.

Aging↗
PubMed2006

Magnetic nanoparticles: inner ear targeted molecule delivery and middle ear implant.

Superparamagnetic iron oxide nanoparticles (SNP) composed of magnetite (Fe(3)O(4)) were studied preliminarily as vehicles for therapeutic molecule delivery to the inner ear and as a middle ear implant capable of producing biomechanically relevant forces for auditory function. Magnetite SNP were synthesized, then encapsulated in either silica or poly (D,L,-Lactide-co-glycolide) or obtained commercially with coatings of oleic acid or dextran. Permanent magnetic fields generated forces sufficient to pull them across tissue in several round window membrane models (in vitrocell culture, in vivo rat and guinea pig, and human temporal bone) or to embed them in middle ear epithelia. Biocompatibility was investigated by light and electron microscopy, cell culture kinetics, and hair cell survival in organotypic cell culture and no measurable toxicity was found. A sinusoidal magnetic field applied to guinea pigs with SNP implanted in the middle ear resulted in displacements of the middle ear comparable to 90 dB SPL.

Animals↗
PubMed1997

Increases in middle ear pressure resulting from counter-diffusion of oxygen and carbon dioxide into the middle ear of monkeys.

The mechanism of middle ear (ME) pressure regulation is incompletely understood. Previously, Hergels and Magnuson reported an unexpected increase in ME pressure for human subjects who partially evacuated their relative positive ME pressures by swallowing. They suggested that a novel, but unknown mechanism for the generation of gas was responsible for the pressure increase. In this experiment, the MEs of rhesus monkeys were inflated with N2 via the eustachian tube and post inflation ME pressures were recorded for up to three hours. Eleven of 20 experiments showed an initial increase in ME pressure caused by the inflation followed by stable pressures for the remainder of the followup period. In 9 of the experiments, a rapid and temporally discrete decrease in ME pressure was observed during the course of followup. Following the observed pressure decrease which was interpreted as a transient eustachian tube opening, ME pressures showed a progressive increase characterized by a kinetic pattern similar to that of the human experiment. To understand the mechanism responsible for this effect, the monkey experiment was simulated using a mathematical model of ME pressure regulation. Free parameters of the model were taken from experimental data for monkeys. The model accurately predicted the time course of pressure change documented in the monkey experiments. The effect is driven by a decrease in the preexisting ME partial pressures of CO2, O2 and H2O consequent to tubal openings at relative positive pressures, with the subsequent counter diffusion of those gases from blood to ME causing the observed increase in total ME pressure. The results reported by Hergels and Magnuson can also be explained by this mechanism.

Animals↗
PubMed2002

Change of guinea pig inner ear pressure by square wave middle ear cavity pressure variation.

The inner ear fluid pressure of guinea pigs was measured during square wave middle ear cavity pressure variation. Time constants were derived for the slopes of the inner ear pressure recovery curves after middle ear pressure change. A "single exponential" function did not fit well and therefore more complicated functions were used for this purpose. For middle ear pressure increasing from zero to a few centimetres of water, returning to zero again, decreasing from zero to minus a few centimetres of water and then returning to zero again, time constants for the inner ear pressure recovery curves were on average 15.0, 8.6, 2.5 and 2.5 s, respectively. The results could not be described using a linear model with constant window membrane compliance and cochlear aqueduct flow resistance. A possible explanation for the large difference in time constants for positive or negative middle ear pressure changes is a dependence on aqueduct flow resistance or round window membrane position.

Animals↗
PubMed1992

Lymphocyte-mucosal interaction of the middle ear mucosa.

The middle ear mucosa possesses immunologic features similar to those of the peripheral mucosa sites in the common mucosal immune system and after mucosal immunization, antigenspecific IgA-forming cells appear in the inflamed mucosa of the tympanic cavity. Recent investigations suggest that lymphocyte migration to lymphoid tissues is regulated by lymphocyte-high endothelial venules (HEV) interaction. However, the lymphocyte migration mechanism to the middle ear mucosa is still unclear. We investigated whether or not organ-specific determinants which lymphocytes bind with are present on the middle ear mucosa by in vivo and in vitro lymphocyte adherence assays by using fluorescein-labeled lymphocytes from various lymphoid tissues. Many lymphocytes from Peyer's patches and hilar lymphnodes adhered on the inflamed middle ear mucosa with or without mucosal immunization, while these cells were not found on the normal tympanic mucosa. The number of the cells was smaller than that in the gastrointestinal mucosa. Lymphocyte adherence to the middle ear mucosa was not suppressed by anti-T cell antibody. These findings suggest that the middle ear mucosa possesses organ-specific mucosal determinants which B-lymphocytes selectively bind with, and that those determinants which regulate lymphocyte migration to the middle ear mucosa differ from those of other mucosae in the gastrointestinal tract.

Animals↗