Abnormal Congenital Location of Stapes' Superstructure: Clinical and Embryological Implications.

Vânia Henriques,Francisco Silva,Jorge Rodrigues,Rafaela Teles,Ângelo Fernandes,Ana Sousa,Fausto Fernandes,Alexandra Gomes,Roberto Estevão

doi:10.1155/2016/2598962

Vânia Henriques, Francisco Silva + Show 7 more

Open Access

https://doi.org/10.1155/2016/2598962

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Abstract

Congenital middle ear malformations are rare. Most part of them are usually associated with other malformations, such as aural atresia, microtia, and dysmorphic craniofacial features. A clinical case of a 24-year-old male with a right-sided conductive hearing loss since his childhood, without craniofacial malformation, is presented. He was proposed for exploratory tympanotomy under the suspicious diagnosis of otosclerosis. The surgery revealed an abnormal location of stapes' superstructure, which was attached to the promontory and had an isolated and mobile osseous footplate in the oval window. A stapes prosthesis was inserted and resulted in closure of the air-bone gap by 25 dB. A review of the literature was also performed using MEDLINE. Two theories diverge on the embryologic origin of the stapes. Our findings seem to be in favour of the theory that defines two different embryologic origins to the stapes.

Highlights

Congenital ossicular chain malformations are present in less than 1 per 15.000 births [1]
Major abnormalities are associated with other malformations, such as aural atresia, microtia, and dysmorphic craniofacial features, involving the external auditory canal (EAC) and the pinna as well as the tympanic cavity and middle ear ossicles
Minor abnormalities appear with a normal tympanic membrane, EAC, and pinna and may involve fixations, defects, or absence of middle ear structures

Summary

Introduction

Congenital ossicular chain malformations are present in less than 1 per 15.000 births [1]. Major abnormalities are associated with other malformations, such as aural atresia, microtia, and dysmorphic craniofacial features, involving the external auditory canal (EAC) and the pinna as well as the tympanic cavity and middle ear ossicles. Minor abnormalities appear with a normal tympanic membrane, EAC, and pinna and may involve fixations, defects, or absence of middle ear structures (malleus, incus, stapes, oval window, and round window). These minor middle ear abnormalities can appear to be isolated or in combination, involving more than one structure [2, 3]. The first hypothesizes that stapes has a dual origin source and the second postulates a single origin [5,6,7]

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