Modelling the effect of round window stiffness on residual hearing after cochlear implantation

Elliott, Stephen J.; Ni, Guangjian; Verschuur, Carl

doi:10.1016/j.heares.2016.08.006

Cited by 34 publications

(36 citation statements)

References 48 publications

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“…Also, it can be noted that the effect of OW and RW stiffness increase has a greater effect in the SSCD condition ( Figure 8B ) compared to the healthy ear. The predicted loss from the RW stiffness increase in Figure 8A is similar to that estimated in Elliott et al ( 41 ), using a similar type of model.…”

Section: Discussionsupporting

confidence: 86%

“…This means that other AC pathways that may become important when the ossicular chain transmission is restricted is omitted in the current model. The model is similar to other lumped-element models of the inner ear where the stimulation is by AC ( 31 , 40 , 41 ). Moreover, the model could predict intra-cochlear sound pressures obtained experimentally in cadaveric temporal bones when the stimulation was a sound pressure in the ear canal ( Figures 3A,B ).…”

Section: Discussionmentioning

confidence: 99%

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Investigation of Mechanisms in Bone Conduction Hyperacusis With Third Window Pathologies Based on Model Predictions

Stenfelt

2020

Front. Neurol.

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A lumped element impedance model of the inner ear with sources based on wave propagation in the skull bone was used to investigate the mechanisms of hearing sensitivity changes with semi-circular canal dehiscence (SSCD) and alterations of the size of the vestibular aqueduct. The model was able to replicate clinical and experimental findings reported in the literature. For air conduction, the reduction in cochlear impedance due to a SSCD reduces the intra-cochlear pressure at low frequencies resulting in a reduced hearing sensation. For bone conduction, the reduced impedance in the vestibular side due to the SSCD facilitates volume velocity caused by inner ear fluid inertia, and this effect dominates BC hearing with a third window opening on the vestibular side. The SSCD effect is generally greater for BC than for AC. Moreover, the effect increases with increased area of the dehiscence, but areas more than the cross section area of the semi-circular canal itself leads to small alterations. The model-predicted air-bone gap for a SSCD of 1 mm 2 is 30 dB at 100 Hz that decreases with frequency and become non-existent at frequencies above 1 kHz. According to the model, this air-bone gap is similar to the air-bone gap of an early stage otosclerosis. The normal variation of the size of the vestibular aqueduct do not affect air conduction hearing, but can vary bone conduction sensitivity by up to 15 dB at low frequencies. Reinforcement of the OW to mitigate hyperacusis with SSCD is inefficient while a RW reinforcement can reset the bone conduction sensitivity to near normal.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Investigation of Mechanisms in Bone Conduction Hyperacusis With Third Window Pathologies Based on Model Predictions

Stenfelt

2020

Front. Neurol.

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“…Furthermore, occlusion of the round window is thought to induce a hearing loss (108, 109). In the series by Silverstein et al, hearing loss was the only subjective survey measure that did not improve after round window reinforcement (106), others have reported a conductive hearing loss (105), and additional series of patients undergoing round window reinforcement by some of the authors have shown a mild hearing loss with this surgery in the non-dehiscent ear (110, 111).…”

Section: Treatmentmentioning

confidence: 99%

Superior Canal Dehiscence Syndrome: Lessons from the First 20 Years

2017

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Superior semicircular canal dehiscence syndrome was first reported by Lloyd Minor and colleagues in 1998. Patients with a dehiscence in the bone overlying the superior semicircular canal experience symptoms of pressure or sound-induced vertigo, bone conduction hyperacusis, and pulsatile tinnitus. The initial series of patients were diagnosed based on common symptoms, a physical examination finding of eye movements in the plane of the superior semicircular canal when ear canal pressure or loud tones were applied to the ear, and high-resolution computed tomography imaging demonstrating a dehiscence in the bone over the superior semicircular canal. Research productivity directed at understanding better methods for diagnosing and treating this condition has substantially increased over the last two decades. We now have a sound understanding of the pathophysiology of third mobile window syndromes, higher resolution imaging protocols, and several sensitive and specific diagnostic tests. Furthermore, we have a treatment (surgical occlusion of the superior semicircular canal) that has demonstrated efficacy. This review will highlight some of the fundamental insights gained in SCDS, propose diagnostic criteria, and discuss future research directions.

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“…The components used to model Z Diff (Fig. 6A) are the same as Elliott et al 2016 and has a parallel orientation as similar to the model of Lynch et al 1982. The model resistance accounts for the distributed partition and scala impedance (Zwislocki, 1963), while the parallel inductor can be attributed to the helicotrema (Dallos, 1970).…”

Section: Discussionmentioning

confidence: 99%

“…Measurements of intracochlear sound pressures and ossicular motions quantify important mechano-acoustic properties of the ear. Knowledge of the impedances of the middle and inner ear are necessary to understand the intricacies of sound transmission through the inner ear (Elliott et al, 2016; Nakajima et al, 2009; Stieger et al, 2013). Our pressure measurement techniques combined with velocity measurements of the stapes and round window are valuable in determining the sound transmission mechanisms that dominate during various forms of inner-ear stimulation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Impedances of the inner and middle ear estimated from intracochlear sound pressures in normal human temporal bones

et al. 2018

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For almost a decade, we have measured intracochlear sound pressures evoked by air conducted (AC) sound presented to the ear canal in many fresh human cadaveric specimens. Similar measurements were also obtained during round window (RW) mechanical stimulation in multiple specimens. In the present study, we use our accumulated data of intracochlear pressures and simultaneous velocity measurements of the stapes or RW to determine acoustic impedances of the cochlear partition, RW, and the leakage paths from scala vestibuli and scala tympani, as well as the reverse middle ear impedance. With these impedances, we develop a computational lumped-element model of the normal ear that illuminates fundamental mechanisms of sound transmission. To calculate the impedances for our model, we use data that passes strict inclusion criteria of: (a) normal middle-ear transfer function defined as the ratio of stapes velocity to ear-canal sound pressure, (b) no evidence of air within the inner ear, and (c) tight control of the pressure sensor sensitivity. After this strict screening, updated normal means, as well as individual representative data, of ossicular velocities and intracochlear pressures for AC and RW stimulation are used to calculate impedances. This work demonstrates the existence and the value of physiological acoustic leak impedances that can sometimes contribute significantly to sound transmission for some stimulation modalities. This model allows understanding of human sound transmission mechanisms for various sound stimulation methods such as AC, RW, and bone conduction, as well as sound transmission related to otoacoustic emissions.

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Modelling the effect of round window stiffness on residual hearing after cochlear implantation

Cited by 34 publications

References 48 publications

Investigation of Mechanisms in Bone Conduction Hyperacusis With Third Window Pathologies Based on Model Predictions

Investigation of Mechanisms in Bone Conduction Hyperacusis With Third Window Pathologies Based on Model Predictions

Superior Canal Dehiscence Syndrome: Lessons from the First 20 Years

Impedances of the inner and middle ear estimated from intracochlear sound pressures in normal human temporal bones

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