The osseous external auditory canal: Surgery, shape, and sound

This thesis describes three aspects of the osseous external auditory canal (OEAC) which are related to each other: Surgery of the OEAC, the shape of the OEAC and the perceived sound quality due to the resonance function of the OEAC. Several aspects of the surgical intervention (Canalplasty) in acquired disease of the OEAC were evaluated with an systematic review of literature. It provides a comprehensive overview of all the different techniques. Subsequently we present the results of our two surgical canalplasty techniques. The relation between the shape of the OEAC is discussed in regard to chronic inflammatory disease of the OEAC. We measured two dimensions of the pretympanic recess. The depth of this recess (DPTR) and the anterior curvature (ACPTR) as we hypothesize that the ability of (self)cleansing of the OEAC is hampered by these two dimensions. We demonstrate that a deeper pretympanic recess is related to chronic inflammatory disease of the OEAC. The role of the surgically altered shape of the OEAC on subjective quality of the perceived sound was investigated. We showed that a significant perceivable deterioration of sound quality was present in radical cavity conditions. We also demonstrated that the canalplasty techniques described in this thesis have effects on the sound quality as well. This thesis indicated that an evidence-based approach was lacking in OEAC surgery. The work in this thesis tried to supply evidence and specify the rationale used regarding the indication and technique for OEAC surgery