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Validation of a Cochlear Implant Patient-Specific Model of the Voltage Distribution in a Clinical Setting

View Article: PubMed Central - PubMed

ABSTRACT

Cochlear Implants (CIs) are medical implantable devices that can restore the sense of hearing in people with profound hearing loss. Clinical trials assessing speech intelligibility in CI users have found large intersubject variability. One possibility to explain the variability is the individual differences in the interface created between electrodes of the CI and the auditory nerve. In order to understand the variability, models of the voltage distribution of the electrically stimulated cochlea may be useful. With this purpose in mind, we developed a parametric model that can be adapted to each CI user based on landmarks from individual cone beam computed tomography (CBCT) scans of the cochlea before and after implantation. The conductivity values of each cochlea compartment as well as the weighting factors of different grounding modes have also been parameterized. Simulations were performed modeling the cochlea and electrode positions of 12 CI users. Three models were compared with different levels of detail: a homogeneous model (HM), a non-patient-specific model (NPSM), and a patient-specific model (PSM). The model simulations were compared with voltage distribution measurements obtained from the backward telemetry of the 12 CI users. Results show that the PSM produces the lowest error when predicting individual voltage distributions. Given a patient-specific geometry and electrode positions, we show an example on how to optimize the parameters of the model and how to couple it to an auditory nerve model. The model here presented may help to understand speech performance variability and support the development of new sound coding strategies for CIs.

No MeSH data available.


Voltage distribution measurements for two CI users, P1 (left panel) and P7 (right panel) participating in the study for stimulating electrodes 4 (top panel), 11 (central panel), and 18 (bottom panel). The mean across electrodes has been subtracted from each voltage distribution.
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Figure 9: Voltage distribution measurements for two CI users, P1 (left panel) and P7 (right panel) participating in the study for stimulating electrodes 4 (top panel), 11 (central panel), and 18 (bottom panel). The mean across electrodes has been subtracted from each voltage distribution.

Mentions: Figure 9 presents the experimental measurement and the model measurements with different levels of detail (HM, NPSM, NPSM2, PSM, optPSM, and optNPSM) for CI users P1 and P7 at three stimulating electrodes sā€‰=ā€‰4, 11, and 18.


Validation of a Cochlear Implant Patient-Specific Model of the Voltage Distribution in a Clinical Setting
Voltage distribution measurements for two CI users, P1 (left panel) and P7 (right panel) participating in the study for stimulating electrodes 4 (top panel), 11 (central panel), and 18 (bottom panel). The mean across electrodes has been subtracted from each voltage distribution.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5120131&req=5

Figure 9: Voltage distribution measurements for two CI users, P1 (left panel) and P7 (right panel) participating in the study for stimulating electrodes 4 (top panel), 11 (central panel), and 18 (bottom panel). The mean across electrodes has been subtracted from each voltage distribution.
Mentions: Figure 9 presents the experimental measurement and the model measurements with different levels of detail (HM, NPSM, NPSM2, PSM, optPSM, and optNPSM) for CI users P1 and P7 at three stimulating electrodes sā€‰=ā€‰4, 11, and 18.

View Article: PubMed Central - PubMed

ABSTRACT

Cochlear Implants (CIs) are medical implantable devices that can restore the sense of hearing in people with profound hearing loss. Clinical trials assessing speech intelligibility in CI users have found large intersubject variability. One possibility to explain the variability is the individual differences in the interface created between electrodes of the CI and the auditory nerve. In order to understand the variability, models of the voltage distribution of the electrically stimulated cochlea may be useful. With this purpose in mind, we developed a parametric model that can be adapted to each CI user based on landmarks from individual cone beam computed tomography (CBCT) scans of the cochlea before and after implantation. The conductivity values of each cochlea compartment as well as the weighting factors of different grounding modes have also been parameterized. Simulations were performed modeling the cochlea and electrode positions of 12 CI users. Three models were compared with different levels of detail: a homogeneous model (HM), a non-patient-specific model (NPSM), and a patient-specific model (PSM). The model simulations were compared with voltage distribution measurements obtained from the backward telemetry of the 12 CI users. Results show that the PSM produces the lowest error when predicting individual voltage distributions. Given a patient-specific geometry and electrode positions, we show an example on how to optimize the parameters of the model and how to couple it to an auditory nerve model. The model here presented may help to understand speech performance variability and support the development of new sound coding strategies for CIs.

No MeSH data available.