Symposium SOFEC 2023 : Bankart osseux.

International audienc

Middle ear influence on otoacoustic emissions. I:Noninvasive investigation of the human transmission apparatus and comparison with model results

Evoked otoacoustic emissions (EOAEs) are generated within the cochlea in response to external sounds, and they can be acoustically detected in the external auditory meatus after backward propagation through the middle ear. In addition to being used to probe the cochlear mechanisms, they are expected to be sensitive to minute changes in middle ear impedance. Systematic measurements of the changes in the vectorial components of EOAEs were carried out after various manipulations of the human middle ear in order to characterize the influence of stiffness and inertia of the stapes and tympanic-membrane systems. For this purpose, stapedius muscle contractions were elicited by high-level contralateral sound, controlled changes in middle ear pressure (range +/- 100 daPa) were produced and the tympanic membrane was loaded with water droplets. A computer model of the middle ear network was implemented using a standard lumped-element electric: analog of the middle ear (Zwislocki's model). Forward and backward transmission changes were simulated and model predictions were compared to experimental data. Apart from the case of positive middle ear pressures. a close qualitative correspondence was found between model and real-ear results. Each of the effects was characterized by a unique pattern of phase and magnitude changes as a function of frequency, in relation to the mechanical characteristics of the involved subsystem (i.e. stapes stiffness, tympanic-membrane stiffness or mass) and its resonance properties. Owing to their high sensitivity; EOAEs could be helpful for an accurate-individual multifrequency analysis of middle ear impedance by comparisons under rest and lest conditions. (C) 2000 Elsevier Science B.V. All rights reserved

On the occurrence of hitherto unknown proteins in the urine of an apparently healthy subject

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Note rectificative

SCOPUS: ar.jNote rectificative au sujet de l'article suivant :http://difusion.academiewb.be/vufind/Record/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/115436/Detailsinfo:eu-repo/semantics/publishe

Middle-ear influence on otoacoustic emissions. II:Contributions of posture and intracranial pressure

Although it seems likely that body till or surgically provoked variations in intracranial pressure (ICP) can result in variations of intralabyrinthine pressure, the channels for pressure transmission remain controversial and the reasons why evoked otoacoustic emissions (EOAEs) exhibit attendant modifications are unclear. The theoretical framework implemented in the companion paper [Avan et al, part I, 2000] provides sensitive and non-invasive means to identify the middle-ear mechanism(s) entailed in EOAE changes. It was thus applied to analyze the influence of posture on EOAE phases and magnitudes as a function of frequency, in a series of experiments involving body tilt from sitting to supine (0 degrees or -30 degrees). Controlled ICP variations were surgically carried out in a series of hydrocephalic patients and the resulting EOAE changes were compared to posture data and model predictions. In all cases, the EOAE changes closely resembled those due to an increase in the stiffness of the stapes' annular ligament, in keeping with the assumption that ICP gets transmitted to intralabyrinthine spaces and modifies the hydrostatic load on the stapes, thereby influencing EOAE features. A small additional contribution of middle-ear pressure to EOAE changes was identified in addition to the main stapes component. Dynamical EOAE measurements showed that sudden ICP changes were transmitted to the inner ear within 8-30 s. The high sensitivity of EOAE phases below 2 kHz to ICP changes, together with the absence of any significant confounding middle-ear effect, favors EOAEs for a reliable non-invasive monitoring of ICP and intralabyrinthine pressures. (C) 2000 Elsevier Science B.V. All rights reserved