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At least 37 records · Page 2Linked to original sources
PubMed1989

Dysmorphogenesis of the mandible, zygoma, and middle ear ossicles in hemifacial microsomia and mandibulofacial dysostosis.

A review of the anatomical changes in patients with various "first arch" syndromes shows that some anomalies (e.g., micrognathia, ear defects) generally appear together. This study tested the hypothesis that the mandible, zygomatic arch, and middle ear ossicles are a developmental field (i.e., when any of these structures is anomalous, the other two will be also). The hypothesis was tested using data from 25 patients with mandibulofacial dysostosis (MFD) and 40 patients with hemifacial microsomia (HFM). Analysis of the pooled data showed that the hypothesis of character association was generally supported. However, the medians suggested that different factors probably played a role in determining how these three anatomical structures were associated in MFD and HFM. Errors in chondrogenesis may have been primarily responsible for the HFM phenotype. Alterations in Meckel and palatoquadrate cartilages would account for the size and shape changes observed in the ossicles and mandible, while changes in cranial base cartilages may explain the changes noted in the zygomatic arch. Since all three structures were equally affected in MFD, it is problematic to use an interference with chondrogenesis as an explanation for the phenotype. We conclude that although the mandible, zygomatic arch, and middle ear ossicles appear to form a "developmental field," the association between structures varies for HFM and MFD. The relatively lesser involvement of the zygomatic arch in HFM than in MFD suggests different pathogeneses for the two diagnostic groups and maybe a useful criterion for judging animal models of HFM.

Ear Ossicles↗
PubMed2006

Middle ear ossicles motion at hearing thresholds with air conduction and bone conduction stimulation.

Hearing threshold data with bone conduction and air conduction stimulation are combined with physiological and mechanical measurements of the middle ear ossicles vibration to compute the vibration level of the ossicles at threshold stimulation. By comparing the displacements of the stapes footplate with the two stimulation modalities and assuming the vibration of the stapes footplate to be the input to the cochlea when stimulation is by air conduction, the importance of middle ear ossicles inertia with bone conduction stimulation is evaluated. Given the limitations of the analysis, the results indicate that the inertia of the middle ear is not an important contribution to the perception of BC sound for frequencies below 1.5 kHz; it seems to contribute to perception of bone conducted sound between the frequencies 1.5 and 3.5 kHz. At frequencies above 4 kHz, the analysis failed since the input to the cochlea is probably not through the oval window with bone conduction stimulation. Comparison of basilar membrane vibration data verified the calculations for frequencies between 0.8 and 3.5 kHz. It was also found that the fluid flow at the round window, rather than at the oval window, reflects the stimulation of the basilar membrane with bone conduction stimulation.

Acoustic Stimulation↗
PubMed1991

Use of the excimer laser in stapes surgery and ossiculoplasty of middle ear ossicles: preliminary report of an experimental approach.

Surgery of the stapes may cause a number of complications, including hearing deficits and balance disorders. This has made it necessary to look for improved techniques. Small-fenestra stapedotomy has recently been popularized. Lasers have been advocated for use in fenestrating the stapes footplate. On the other hand, sculpting the middle ear ossicles during tympanoplasty is often necessary for the reconstruction of the ossicular chain and the improvement of sound conduction. Using an excimer laser with a wavelength of 193 nm, fenestrations of the footplate and ossicular sculpting were performed on ossicles obtained during ear surgery and from human cadaver temporal bones. The results indicate that the excimer laser can be used effectively and accurately on an experimental basis and that further research is needed before this method can be used for clinical purposes.

Cerebrospinal Fluid↗
PubMed1988

[Dentin ossicle prostheses (DOP)--a new concept in replacing the ear ossicles].

The variety of materials used for replacement of the ossicles is proof enough that no single material can satisfy all criteria: availability, mouldability, stability and biocompatibility. The trouble-free availability as well as the excellent mouldability enable the development of a principle of preparation of ossicular replacement prosthesis from homologous dentine. The moulding of the dentine ossicular prosthesis is simple and can be performed with an equipment available at any otologic department.

Bioprosthesis↗
PubMed1988

[Mechanics of the ear ossicle chain in static pressures. I. The normal middle ear].

The mechanics of the ossicle chain, induced by variations of static air pressure ranging from 0 to +/- 400 H2O, were analysed in an experimental study of 25 temporal bone preparations. The three-dimensional movements of the umbo, the proc. lenticularis and stapes at these pressures, applied at the external ear canal, were measured microscopically. Direct high-grade radiographic magnification technique demonstrated these displacements dynamically. In the normal ossicle chain, the air pressure-induced inward-outward excursions of the malleus are transformed by the gliding incudo-malleal joint, resulting predominantly in an upward and downward movement of the lenticular process. Thus, the incudo-stapedial joint can glide, and the stapes is uncoupled from the extensive displacements of the drum membrane and malleus. This mode of motion accounts for some anatomical details of the middle ear and explains results of former studies of ossicle vibrations produced by unphysiologically high sound pressures.

Adolescent↗