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Middle Ear Cavity (middle + ear_cavity)

Distribution by Scientific Domains

Medical Sciences	66%

Selected Abstracts

Evolution of the middle ear apparatus in talpid moles

JOURNAL OF MORPHOLOGY, Issue 6 2006
Matthew J. Mason
Abstract The middle ear structures of eight species of mole in the family Talpidae (Mammalia: Eulipotyphla) were studied under light and electron microscopy. Neurotrichus, Parascalops, and Condylura have a simple middle ear cavity with a loose ectotympanic bone, ossicles of a "microtype" morphology, and they retain a small tensor tympani muscle. These characteristics are ancestral for talpid moles. Talpa, Scalopus, Scapanus, and Parascaptor species, on the other hand, have a looser articulation between malleus and ectotympanic bone and a reduced or absent orbicular apophysis. These species lack a tensor tympani muscle, possess complete bullae, and extensions of the middle ear cavity pneumatize the surrounding basicranial bones. The two middle ear cavities communicate in Talpa, Scapanus, and Parascaptor species. Parascaptor has a hypertrophied malleus, a feature shared with Scaptochirus but not found in any other talpid genus. Differences in middle ear morphology within members of the Talpidae are correlated with lifestyle. The species with middle ears closer to the ancestral type spend more time above ground, where they will be exposed to high-frequency sound: their middle ears appear suited for transmission of high frequencies. The species with derived middle ear morphologies are more exclusively subterranean. Some of the derived features of their middle ears potentially improve low-frequency hearing, while others may reduce the transmission of bone-conducted noise. By contrast, the unusual middle ear apparatus of Parascaptor, which exhibits striking similarities to that of golden moles, probably augments seismic sensitivity by inertial bone conduction. J. Morphol. © 2006 Wiley-Liss, Inc. [source]

Otitis media in a mouse model for Down syndrome

INTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 5 2009
Fengchan Han
Summary The Ts65Dn mouse shares many phenotypic characteristics of human Down syndrome. Here, we report that otitis media, characterized by effusion in the middle ear and hearing loss, was prevalent in Ts65Dn mice. Of the 53 Ts65Dn mice tested, 81.1% had high auditory-evoked brainstem response (ABR) thresholds for at least one of the stimulus frequencies (click, 8 kHz, 16 kHz and 32 kHz), in at least one ear. The ABR thresholds were variable and showed no tendency toward increase with age, from 2 to 7 months of age. Observation of pathology in mice, aged 3,4 months, revealed middle ear effusion in 11 of 15 Ts65Dn mice examined, but only in two of 11 wild-type mice. The effusion in each mouse varied substantially in volume and inflammatory cell content. The middle ear mucosae were generally thickened and goblet cells were distributed with higher density in the epithelium of the middle ear cavity of Ts65Dn mice as compared with those of wild-type controls. Bacteria of pathogenic importance to humans also were identified in the Ts65Dn mice. This is the first report of otitis media in the Ts65Dn mouse as a model characteristic of human Down syndrome. [source]

Evolution of the middle ear apparatus in talpid moles

Malignancies of the Ear in Irradiated Patients of Nasopharyngeal Carcinoma

THE LARYNGOSCOPE, Issue 12 2008
Wu-Chia Lo MD
Abstract Objectives/Hypothesis: To report on the clinical profiles and treatment experiences of patients with second primary ear malignancy after treatment of nasopharyngeal carcinoma (NPC). Study Design: Retrospective case series. Methods: A retrospective review of the clinical outcomes and pathology of 11 irradiated NPC patients who subsequently had second primary malignancies of the ear at a single institution. Results: Ten tumors were squamous cell carcinoma and one tumor was chondrosarcoma occurring within the radiation field of previous treatment for NPC. The interval between previous radiotherapy and diagnosis of ear malignancy was 3 to 27 years with a median time of 17 years. Six tumors were located in the external auditory canal, two in the middle ear cavity, two in the periauricular region and one in the mastoid cavity. Four patients underwent surgery, and the other seven patients underwent surgery plus adjuvant radiotherapy. The 3-year disease-free and overall survival rates were 30.3% and 20%, respectively. Conclusions: Postirradiated malignancy of the ear is extremely rare, but is one of the causes of death for NPC long-term survivors despite curative-intended treatment with surgery plus adjuvant radiotherapy is instituted. [source]

Hearing Levels in Patients With Microtia: Correlation With Temporal Bone Malformation

THE LARYNGOSCOPE, Issue 3 2007
Shin-ichi Ishimoto MD
Abstract Objective: To evaluate the relationship between hearing level and temporal bone abnormalities in patients with microtia. Study Design: Retrospective case series study between 1992 and 2004. Setting: Academic, tertiary care referral medical center. Patients: We evaluated 115 ears of 89 patients (68 males, 21 females; mean age, 11 yr; range, 5-44 yr) with microtia. Main Outcome Measures: Hearing level was examined in patients with microtia. Developmental abnormalities of the temporal bone were evaluated by Jahrsdoerfer's computed tomography (CT) scoring system using high-resolution CT (HRCT) scans of the temporal bone. Temporal bone malformation scores were divided into four subgroups: ossicular development, windows connected to the cochlea, aeration of the middle ear cavity, and facial nerve aberration. Patients were divided into the stenosis and atresia groups on the basis of the appearance of the external auditory canal (EAC). We also evaluated the relationships between hearing level and four subtotal scores of the HRCT findings in the stenosis and atresia groups. Results: There was no relationship between hearing level and total points of HRCT scoring system or between hearing level and severity of microtia scored by Marx classification. With regard to subtotal points related to ossicles (4 points), the hearing level in ears with low scores (<2) (64.7 ± 1.6 dB) was significantly different (P = .03) from that in ears with high scores (,2) (54.0 ± 2.8 dB) in the stenosis group. In the atresia group, the hearing level was 64.3 ± 2.2 dB in ears with low scores and 62.3 ± 1.1 in ears with high scores (P > .5). As for subtotal points related to the windows connected to cochlea (2 points), the hearing level was 64.8 ± 2.6 dB in ears with low scores (0) and 55.9 ± 2.4 dB in ears with high scores (> = 1) in the stenosis group. In the atresia group, the hearing level was 67.7 ± 2.3 dB in ears with low scores and 61.5 ± 1.0 in ears with high scores. There was significant difference between ears with low and high scores in the stenosis group (P = .03) and atresia group (P = .009). There was no significant difference between ears with low and high scores with respect to the subtotal points related to aeration of the middle ear cavity and aberration of the facial nerve. Conclusion: The hearing level in microtic ears correlated with the formation of oval/round windows and ossicular development but not with the degree of middle ear aeration, facial nerve aberration, or severity of microtia. The hearing level can also serve as an indictor, such as the HRCT findings, to determine whether a subject's hearing will likely improve after reconstructive surgery. [source]

Antigenic as Well as Nonantigenic Stimuli Induce Similar Middle Ear Responses in the Rat,

THE LARYNGOSCOPE, Issue 2 2003
Edith L. G. M. Tonnaer MSc
Abstract Objectives/Hypothesis The observation that during otitis media many different types of micro-organisms have been cultured from effusions indicate that, once present in the middle ear cavity, most types of micro-organisms are able to trigger an inflammatory reaction leading to otitis media. The present study was designed to determine the middle ear response after injection of different substances into the middle ear cavity. Study Design To determine whether and to what extent an inflammatory response of the middle ear depends on the entering agent, the response in the tympanic cavity was studied by otomicroscopy and histological examination after inoculation of various substances. Methods Lewis rats were inoculated in transtympanic fashion either with live or heat-killed bacteria (pathogenic and nonpathogenic), Keyhole limpet hemocyanin, active charcoal, or saline. The mucosal response of the challenged middle ears was studied histologically. Results Irrespective of the inoculated substance, no essential differences in the mucosal response were found. The intensity of the inflammatory response was greater when live bacteria were inoculated. Conclusions The present study demonstrates that any substance reaching the middle ear cavity is likely to induce otitis media. These observations emphasize the role of the eustachian tube as "porte d'entrée" in the pathogenesis of this disorder. Determination of specific aspects of the eustachian tube involved in protection or in facilitating bacterial translocation will be important for the understanding of the pathogenesis of otitis media and the subsequent development of new therapeutic strategies. In addition, elucidation of bacterial factors involved in the process of colonization and translocation will be of equal importance. [source]