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

Experimental study of superior semicircular canal dehiscence in temporal bone

Meeting Abstract

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. Doc07hno032

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/hno2007/07hno032.shtml

Veröffentlicht: 8. August 2007

© 2007 Bethge 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: Dehiscence of the bone covering the superior semicircular canal is an aberration where the membranous labyrinth fits directly to the dura. The resulting symptoms can be understood based upon abnormal pressure transmission in the system of the inner ear. Some of the patients not only show vestibular symptoms but also auditory symptoms such as conductive hearing loss in spite of an intact middle ear.

Method: In this experimental study the influence of superior semicircular canal dehiscence on conductive hearing was measured in temporal bone with intact ossicles. A sound of fixed volume and various frequencies was applied to the external ear canal and measured with a microphone at the round window either with intact or defective bone over the superior semicircular canal.

Results: Disruption of the bone covering the superior semicircular canal showed a frequency dependant conductive hearing loss up to 2500 Hz. Especially in lower frequencies, values to the point of 20 dB were reached.

Conclusion: Dehiscence of the bone covering the superior semicircular canal leads to conductive hearing loss in temporal bone despite intact air conduction mechanisms in the middle ear. This apparent conductive hearing loss could be due to a third window formed by the dehiscence which causes a dissipation of acoustic energy transmitted through altered inner ear fluid-movements. Removal of the dehiscence leads to reconstituted inner ear mechanics.