Intraoperative Impedance-Based Estimation of Cochlear Implant Electrode Array Insertion Depth

Aebischer, Philipp; Meyer, Stefan; Caversaccio, Marco; Wimmer, Wilhelm

doi:10.1109/tbme.2020.3006934

Cited by 41 publications

(46 citation statements)

References 39 publications

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“…To enable a large number of insertions, we produced electrode array dummies that match the mechanical characteristics of a long free-fitting clinical array (Flex 28 , MED-EL GmbH, Innsbruck, Austria) [39]. We chose this particular type of array because it is the most commonly used in our clinic and enables us to monitor deep insertions [40], [41]. The dummies have the same dimensions as the clinical arrays, with a circular cross-section (diameter 0.8 mm) at the base morphing into an elliptical shape (0.5 mm × 0.4 mm) at the tip.…”

Section: A Experimental Setupmentioning

confidence: 99%

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Aebischer

Mantokoudis

Weder

et al. 2022

IEEE Trans. Biomed. Eng.

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The insertion of the electrode array is a critical step in cochlear implantation. Herein we comprehensively investigate the impact of the alignment angle and feed-forward speed on deep insertions in artificial scala tympani models with accurate macro-anatomy and controlled frictional properties. Methods: Motorized insertions (n=1033) were performed in six scala tympani models with varying speeds and alignment angles. We evaluated reaction forces and micrographs of the insertion process and developed a mathematical model to estimate the normal force distribution along the electrode arrays. Results: Insertions parallel to the cochlear base significantly reduce insertion energies and lead to smoother array movement. Non-constant insertion speeds allow to reduce insertion forces for a fixed total insertion time compared to a constant feed rate. Conclusion: In cochlear implantation, smoothness and peak forces can be reduced with alignment angles parallel to the scala tympani centerline and with non-constant feed-forward speed profiles. Significance: Our results may help to provide clinical guidelines and improve surgical tools for manual and automated cochlear implantation.

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Section: A Experimental Setupmentioning

confidence: 99%

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Aebischer

Mantokoudis

Weder

et al. 2022

IEEE Trans. Biomed. Eng.

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“…The relationship between insertion depth and monopolar impedances (Fig. 1, top left) was identified by Giardina et al [14] and Aebischer et al [15]; Aebischer et al showed a relationship strong enough to enable accurate prediction of insertion depth based on monopolar impedance measurements alone.…”

Section: Introductionmentioning

confidence: 88%

“…This is because monopolar access resistance measures the resistive path between an intracochlear electrode and the ground. As the conductivity of the intracochlear fluid is nine times higher than the conductivity of bone [29], while the transversal resistances of the basal-most electrodes are on average 16 times smaller than the other transversal resistances [15], a large proportion of the current will flow through the intracochlear fluid and exit basally. This causes the overall monopolar impedance to be higher for deeper insertions into the cochlea.…”

Section: B Insertion Depth and Impedancementioning

confidence: 97%

Predicting Cochlear Implant Electrode Placement Using Monopolar, Three-Point and Four-Point Impedance Measurements

Sijgers

Huber

Tabibi

et al. 2022

IEEE Trans. Biomed. Eng.

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This study aimed to investigate the relationship between cochlear implant (CI) electrode distances to the cochlea's inner wall (the modiolus) and electrical impedance measurements made at the CI's electrode contacts. We introduced a protocol for "three-point impedances" in which we recorded bipolar impedances in response to monopolar stimulation at a neighboring electrode. We aimed to assess the usability of three-point impedances and two existing CI impedance measurement methods (monopolar and four-point impedances) for predicting electrode positioning during CI insertion. Methods: Impedances were recorded during stepwise CI electrode array insertions in cadaveric human temporal bones. The positioning of the electrodes with respect to the modiolus was assessed at each step using cone beam computed tomography. Linear mixed regression analysis was performed to assess the relationship between the impedances and electrode-modiolar distances. The experimental results were compared to clinical impedance data and to an existing lumped-element model of an implanted CI. Results: Three-point and four-point impedances strongly correlated with electrode-modiolar distance. In contrast, monopolar impedances were only minimally affected by changes in electrode positioning with respect to the modiolus. An overall model specificity of 62% was achieved when incorporating all impedance parameters. This specificity could be increased beyond 73% when prior expectations of electrode positioning were incorporated in the model. Conclusion: Three-point and four-point impedances are promising measures to predict electrode-modiolar distance in real-time during CI insertion. Significance: This work shows how electrical impedance measurements can be used to predict the CI's electrode positioning in a biologically realistic model.

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“…Electrical impedance is also used for detection of EA insertion failure and translocation [30][31][32]. Most recently, electrode impedance recordings were used for insertion depth estimation [33].…”

Section: Introductionmentioning

confidence: 99%

Real-Time Data-Driven Approach for Prediction and Correction of Electrode Array Trajectory in Cochlear Implantation

Hafeez

Boulgouris

et al. 2022

Applied Sciences

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Cochlear implants provide hearing perception to people with severe to profound hearing loss. The electrode array (EA) inserted during the surgery directly stimulates the hearing nerve, bypassing the acoustic hearing system. The complications during the EA insertion in the inner ear may cause trauma leading to infection, residual hearing loss, and poor speech perception. This work aims to reduce the trauma induced during electrode array insertion process by carefully designing a sensing method, an actuation system, and data-driven control strategy to guide electrode array in scala tympani. Due to limited intra-operative feedback during the insertion process, complex bipolar electrical impedance is used as a sensing element to guide EA in real time. An automated actuation system with three degrees of freedom was used along with a complex impedance meter to record impedance of consecutive electrodes. Prediction of EA direction (medial, middle, and lateral) was carried out by an ensemble of random forest, shallow neural network, and k-nearest neighbour in an offline setting with an accuracy of 86.86%. The trained ensemble was then utilized in vitro for prediction and correction of EA direction in real time in the straight path with an accuracy of 80%. Such a real-time system also has application in other electrode implants and needle and catheter insertion guidance.

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Intraoperative Impedance-Based Estimation of Cochlear Implant Electrode Array Insertion Depth

Cited by 41 publications

References 39 publications

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions

Predicting Cochlear Implant Electrode Placement Using Monopolar, Three-Point and Four-Point Impedance Measurements

Real-Time Data-Driven Approach for Prediction and Correction of Electrode Array Trajectory in Cochlear Implantation

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