gms | German Medical Science

78. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e. V.

Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e. V.

16.05. - 20.05.2007, München

Mechanical properties of the tegmen tympani and localization of congenital defects

Meeting Abstract

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  • corresponding author Miklos Toth - ENT Department, Johannes Gutenberg-University Mainz, Mainz, Germany
  • Kai Helling - ENT Department, Johannes Gutenberg-University Mainz, Mainz, Germany
  • Wolf Mann - ENT Department, Johannes Gutenberg-University Mainz, Mainz, Germany

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 78th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Munich, 16.-20.05.2007. Düsseldorf, Köln: German Medical Science; 2007. Doc07hno115

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/hno2007/07hno115.shtml

Veröffentlicht: 8. August 2007

© 2007 Toth et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction: Studies about cadaveric temporal bones have presented an incidence of acquired and congenital bone defects in the tegmen of between 20 to 30%. Clinical data show typical localizations of congenital defects in the area of the geniculate ganglion. Although there are two theories about the pathogenesis of these tegmental defects but both could not explain the exact developmental process forming a bony defect in the tegmen tympani. This study set out to demonstrate the normal developmental steps of the tegmen tympani and by that try to explain typical localization of congenital tegmental defects.

Methods and materials: For this study 122 macerated and formalin fixed human temporal bones from 20th fetal week to adults were observed and preparated.

Results: Developmentally the tegmen tympani is built up from two anlagen, the squamous part laterally and the petrous part medially. The medial part arises from the otic capsule during chondral ossification forms the tegmental process of the petrous part. The lateral part shows membranous ossification. Morphologically the tegmen tympani can be divided into two layers, a bony plate superiorly and a trabecular network inferiorly. The later has a beam-like central trabecule, the transverse tignum. Smaller trabeculae, tigilla strengthen the tignum on both sides which also form the bony air-filled cells of the tegmen.

Conclusion: Congenital defects develop ventral to the anterior semicircular canal, i.e. near the geniculate ganglion caused by ossification-failure of the tegmental process of the inner ear. After birth the tegmen tympani functions as a ‘roof trust’ of the middle formed by a bony plate. Acquired defects developing from the intracranial space, cause first disappearance of the superior layer without mechanical weakness of the tegmen because of the remaining trabecular network. Pathological processes or surgical interventions in the middle ear first destroy the trabecular network but the bony plate remains temporarily intact. Its absence can later produce a locus minoris resistentiae of the tegmen tympani allowing the development of meningo- or meningoencephalocele.