A Sleeve-Based, Micromotion Avoiding, Retractable and Tear-Opening (SMART) Insertion Tool for Cochlear Implantation

Aebischer, Philipp; Weder, Stefan; Mantokoudis, Georgios; Vischer, Mattheus; Caversaccio, Marco; Wimmer, Wilhelm

doi:10.1109/tbme.2022.3204069

Cited by 3 publications

(5 citation statements)

References 31 publications

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“…Alternatively, the electrode array can be stabilized during insertion using a guide tube (42) or a manual insertion tool previously developed at our institution. This tool deflects the electrode array intracochlearly, allowing further reduction of maximum forces (18).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, we mounted a slide potentiometer to track the opening and closing of the surgical forceps, and recorded the surgical view through the microscope using an external recorder (Storz IMAGE1 HD with TELE PACK+). The setup was previously described in full detail in a study that evaluated a novel manual insertion tool (18). Figure 1 shows the temporal bone model during an insertion as seen by the operator, together with a photomicrograph of the scala tympani model containing a partially inserted electrode array.…”

Section: Methodsmentioning

confidence: 99%

“…The integral of the applied force as a function of the insertion depth yields the total energy required to insert the electrode array, called the insertion work (18). To aid in our analysis, we defined a new metric, called the work midpoint , which corresponds to the point where the preceding and succeeding divisions of the insertion require equal amounts of work.…”

Section: Methodsmentioning

confidence: 99%

“…An estimation of the electrode centerline was automatically computed from the latter using a previously described method (21). The centerline enabled us to calculate secondary metrics such as linear and angular insertion depth (the length of the centerline starting at the round window, and the azimuth of the polar coordinates, respectively), insertion speed (the time derivative of the linear insertion depth), and the transverse position of the electrode array relative to the scala tympani centerline at an intracochlear position of 90° (18).…”

Section: Outcome Measuresmentioning

confidence: 99%

“…Therefore, in this study, we aim to comprehensively monitor intracochlear pressure, insertion forces, and electrode array movement during the phases of electrode array insertion and implant management using an artificial model of the temporal bone that replicates the 3D geometry of the scala tympani and incorporates realistic friction characteristics (17,18). Our objective is to deepen our understanding of the factors that may contribute to inner ear injury during the implantation process.…”

Section: Introductionmentioning

confidence: 99%

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Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model

Aebischer,

Weder,

Vischer

et al. 2024

Otol Neurotol

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Objectives The aim of this study is to improve our understanding of the mechanics involved in the insertion of lateral wall cochlear implant electrode arrays. Design A series of 30 insertion experiments were conducted by three experienced surgeons. The experiments were carried out in a previously validated artificial temporal bone model according to established soft surgery guidelines. The use of an in vitro setup enabled us to comprehensively evaluate relevant parameters, such as insertion force, intracochlear pressure, and exact electrode array position in a controlled and repeatable environment. Results Our findings reveal that strong intracochlear pressure transients are more frequently caused during the second half of the insertion, and that regrasping the electrode array is a significant factor in this phenomenon. For choosing an optimal insertion speed, we show that it is crucial to balance slow movement to limit intracochlear stress with short duration to limit tremor-induced pressure spikes, challenging the common assumption that a slower insertion is inherently better. Furthermore, we found that intracochlear stress is affected by the order of execution of postinsertion steps, namely sealing the round window and posterior tympanotomy with autologous tissue and routing of the excess cable into the mastoid cavity. Finally, surgeons’ subjective estimates of physical parameters such as speed, smoothness, and resistance did not correlate with objectively assessed measures, highlighting that a thorough understanding of intracochlear mechanics is essential for an atraumatic implantation. Conclusion The results presented in this article allow us to formulate evidence-based surgical recommendations that may ultimately help to improve surgical outcome and hearing preservation in cochlear implant patients.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Outcome Measuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model

Aebischer,

Weder,

Vischer

et al. 2024

Otol Neurotol

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Quantitative in-vitro assessment of a novel robot-assisted system for cochlear implant electrode insertion

Aebischer,

Anschuetz,

Caversaccio

et al. 2024

Int J CARS

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Purpose As an increasing number of cochlear implant candidates exhibit residual inner ear function, hearing preservation strategies during implant insertion are gaining importance. Manual implantation is known to induce traumatic force and pressure peaks. In this study, we use a validated in-vitro model to comprehensively evaluate a novel surgical tool that addresses these challenges through motorized movement of a forceps. Methods Using lateral wall electrodes, we examined two subgroups of insertions: 30 insertions were performed manually by experienced surgeons, and another 30 insertions were conducted with a robot-assisted system under the same surgeons’ supervision. We utilized a realistic, validated model of the temporal bone. This model accurately reproduces intracochlear frictional conditions and allows for the synchronous recording of forces on intracochlear structures, intracochlear pressure, and the position and deformation of the electrode array within the scala tympani. Results We identified a significant reduction in force variation during robot-assisted insertions compared to the conventional procedure, with average values of 12 mN/s and 32 mN/s, respectively. Robotic assistance was also associated with a significant reduction of strong pressure peaks and a 17 dB reduction in intracochlear pressure levels. Furthermore, our study highlights that the release of the insertion tool represents a critical phase requiring surgical training. Conclusion Robotic assistance demonstrated more consistent insertion speeds compared to manual techniques. Its use can significantly reduce factors associated with intracochlear trauma, highlighting its potential for improved hearing preservation. Finally, the system does not mitigate the impact of subsequent surgical steps like electrode cable routing and cochlear access sealing, pointing to areas in need of further research.

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The role of pressure and friction forces in automated insertion of cochlear implants

Fröhlich,

Deutz,

Wangenheim

et al. 2024

Front. Neurol.

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ObjectivesDespite the success of cochlear implant (CI) surgery for hearing restoration, reducing CI electrode insertion forces is an ongoing challenge with the goal to further reduce post-implantation hearing loss. While research in this field shows that both friction and quasistatic pressure forces occur during CI insertion, there is a lack of studies distinguishing between these origins. The present study was conducted to analyze the contribution of both force phenomena during automated CI insertion.MethodsFive MED-EL FLEX28 CI electrode arrays were inserted into both a regular and uncoiled version of the same average scala tympani (ST). Both ST models had a pressure release hole at the apical end, which was kept open or closed to quantify pressure forces. ST models were filled with different sodium dodecyl sulfate (SDS) lubricants (1, 5, and 10% SDS, water). The viscosity of lubricants was determined using a rheometer. Insertions were conducted with velocities ranging from v= 0.125 mm/s to 2.0 mm/s.ResultsViscosity of SDS lubricants at 20°C was 1.28, 1.96, and 2.51 mPas for 1, 5, and 10% SDS, respectively, which lies within the values reported for human perilymph. In the uncoiled ST model, forces remained within the noise floor (maximum: 0.049 × 10−3 N ± 1.5 × 10−3 N), indicating minimal contribution from quasistatic pressure. Conversely, forces using the regular, coiled ST model were at least an order of magnitude larger (minimum: Fmax = 28.95 × 10−3 N, v = 1 mm/s, 10% SDS), confirming that friction forces are the main contributor to total insertion forces. An N-way ANOVA revealed that both lubricant viscosity and insertion speed significantly reduce insertion forces (p < 0.001).ConclusionFor the first time, this study demonstrates that at realistic perilymph viscosities, quasistatic pressure forces minimally affect the total insertion force profile during insertion. Mixed friction is the main determinant, and significantly decreases with increaseing insertion speeds. This suggests that in clinical settings with similar ST geometries and surgical preparation, quasistatic pressure plays a subordinate role. Moreover, the findings indicate that managing the hydrodynamics of the cochlear environment, possibly through pre-surgical preparation or the use of specific lubricants, could effectively reduce insertion forces.

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A Sleeve-Based, Micromotion Avoiding, Retractable and Tear-Opening (SMART) Insertion Tool for Cochlear Implantation

Cited by 3 publications

References 31 publications

Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model

Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model

Quantitative in-vitro assessment of a novel robot-assisted system for cochlear implant electrode insertion

The role of pressure and friction forces in automated insertion of cochlear implants

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