Experimental investigation of the effect of middle ear in bone conduction

Intracochlear pressure in cadaver heads under bone conduction and intracranial fluid stimulation

“…In order to provide an optical access to the stapes and the promontory, an anterior mastoidectomy was performed, as described in Dobrev et al (2020a) . The facial nerve and the chorda tympani were identified and a wide posterior tympanotomy was opened by removing the bone between the nerves as well as the facial nerve in the mastoidal segment.…”

“…3D stapes velocity (V STAP ) was used to check the middle-ear transfer function (METF) under AC, against existing standard ( ASTM, F2504-05 ). Under BC, V STAP was used as a proxy to the fluid-volume velocity of the cochlear fluid at its interface with the middle ear ( Stenfelt et al, 2002 ;Dobrev et al, 2020a ). 3.…”

“…Although inertia of the perilymphe and deformation (e.g., compression and expansion) of the otic capsule are dominant under physiological conditions ( Stenfelt, 2016 ), each of these BC mechanisms probably have different onset intensities and different phases, prevalence at different frequency bands, or becomes important in pathological situations. Several of these BC pathways have been evaluated previously, both experimentally ( Stenfelt et al, 2002( Stenfelt et al, , 2003Stenfelt, 2015 ;Stump et al, 2018 ;Dobrev et al, 2019 ;Dobrev et al, 2020a ) and numerically ( Stenfelt, 2016 ;Chang et al, 2016 ). The least understood pathway of sound propagation to the inner ear is via the intracranial contents, such as the brain and CSF, through the internal auditory canal and cochlea aqueduct, to the perilymph of the inner ear and vestibule.…”

Objective preclinical measures for bone conduction implants

“…In contrast with live patients who can provide subjective feedback to evaluate the hearing sensation, tests in cadaveric specimens require objective measures. Currently, three measures are commonly employed: intracochlear pressure ( Greene et al, 2015 ; Borgers et al, 2019 ; Mattingly et al, 2020 ; Fierens et al, 2022 ; Putzeys et al, 2022 ), promontory velocity ( Stenfelt and Goode, 2005 ; Rosowski et al, 2007 ; Dobrev et al, 2016 , 2020 , 2023 ; Roosli et al, 2016 ; Rigato et al, 2019 ; Ghoncheh et al, 2021 ; Prodanovic and Stenfelt, 2021 ), and ear canal pressure ( Mertens et al, 2014 ; Nie et al, 2022 ).…”

“…While it is an invasive procedure, as the cochlear surface must be visible, it does not require the cochlear capsule to be surgically opened. Access can be achieved through a canal wall-up mastoidectomy, an enlarged posterior tympanotomy without facial nerve removal ( Rosowski et al, 2007 ; Dobrev et al, 2020 ), or through the ear canal when the tympanic membrane is removed ( Rigato et al, 2019 ; Ghoncheh et al, 2021 ). The main advantage of this technique is its good signal-to-noise ratio.…”