Comparative Analysis of Robotics-Assisted and Manual Insertions of Cochlear Implant Electrode Arrays

Preclinical evaluation of a hydraulic actuation system with guide tube for robotic cochlear implant electrode insertion

BACKGROUND

Automated insertion of the cochlear implant electrode array can reduce the risk of intracochlear trauma. To address this, our group previously developed a hydraulic electrode insertion device, the Cochlea Hydrodrive (CHD), which automates the process using a syringe piston driven by an infusion pump. This study aims to characterize the hydraulic actuation process of the CHD and to preclinically evaluate its design.

METHODS

A camera-based motion tracking test setup was developed to obtain hydraulic motion profiles. Various syringes were evaluated for their actuation properties and the optimal syringe was selected. The CHD design was adapted based on the selected syringe, incorporating a slotted stainless steel guide tube to surround the electrode during insertion. This enhanced design was tested in ex vivo insertion trials into human head specimens.

RESULTS

The final design of the CHD demonstrated smooth and steady motion profiles at all tested velocities (0.4 mm/s, 0.1 mm/s, 0.03 mm/s). Ex vivo insertion trials confirmed these findings, with the guide tube facilitating easy alignment of the CHD in front of the round window and preventing electrode buckling.

CONCLUSION

Our study validates that the CHD provides reliably smooth actuation properties despite its low complexity. The use of a guide tube appears promising and could further enhance the standardization of automated electrode insertion.

Qualifying Cochlear Implant Candidates-Does it Matter How Patients Are Qualified?

OBJECTIVE

Evaluate variable qualification criteria for cochlear implant (CI) recipients and 12-month speech perception outcomes.

STUDY DESIGN

Retrospective cohort study.

SETTING

HERMES national database and nonoverlapping single-institution CI database.

PATIENTS

A total of 2,124 adult unilateral CI recipients categorized by qualifying status: AzBio in quiet (n = 1,239), +10 dB SNR (but not in quiet; n = 519), +5 dB SNR (but not in quiet or +10 dB SNR; n = 366); CNC ≤40% (n = 1,037), CNC 41% to 50% (n = 31), and CNC 51% to 60% (n = 20).

INTERVENTIONS

CI.

MAIN OUTCOME MEASURES

Pre- and 12-month postoperative speech perception performance. Clinically significant improvement was defined as ≥15% gain.

RESULTS

Quiet qualifiers experienced improvement in all listening conditions, whereas +10 dB SNR and +5 dB SNR qualifiers only improved in their qualifying condition and implanted ear CNC. When stratified by expanded Medicare criteria (binaural AzBio ≤60% correct), patients that qualified in quiet experienced improvements regardless of qualifying threshold or background noise. However, those that qualified in noise and AzBio ≤60% experienced mixed results in quiet and limited gain in background noise. When ≤60% criteria was applied to CNC of the worse ear, ≤40% qualifiers experienced large improvements in all tested conditions, but those who qualified by 41% to 50% or 51% to 60% only demonstrated modest improvements in AzBio sentence testing.

CONCLUSIONS

Quiet qualifiers improved in all testing conditions, while those qualifying in noise improved in their qualifying condition. Patients who qualified by expanded Medicare criteria (≤60%) showed improvement when qualifying with AzBio in quiet, but should be used with caution when qualifying patients in background noise or CNC due to more limited gains in performance.

Robot-assisted vs. manual cochlear implant electrode array insertion in four children

PURPOSE

Evaluate the feasibility and safety of a robotic electrode insertion in pediatric cochlear implantation and compare the results with manually inserted electrodes in the same subject.

METHODS

Retrospective case series review of four children who underwent bilateral cochlear implantation with the same array: on one side, the array was inserted using the robot, while on the other side the array was inserted manually. Behavioural and electrophysiological measures were compared.

RESULTS

The duration of surgery when the robot was adopted was significantly longer than when a manual insertion was performed (161.15 ± 27.59 minutes vs. 122.6 ± 37.71 min, paired t-test: p = 0.029). Moreover, robotic electrode insertion was significantly slower (average insertion speed 0.3 mm/second vs. 0.52 ± 0.17 mm/s, paired t-test: p = 0.0055). On radiologic examination, none of the arrays was misplaced. Impedance, both at activation and at one year of cochlear implant use, was significantly lower on the robotic side in monopolar mode compared to the manual side (mean 9.64 ± 2.41kΩ and 9.97 ± 1.39 kΩ vs. 10.43 ± 2.69 kΩ and 10.94 ± 1.11 kΩ, paired t test, p = 0.0251 and p = 0.0061, respectively). Both the threshold stimulation level and the most comfortable loud stimulation level were significantly lower in the robotic inserted ear compared to the manually inserted ear (mean 108.1 ± 5.98 and 169 ± 4.84 vs. 112.1 ± 7.43 and 172.7 ± 6.83, respectively, paired t test p < 0.0001).

CONCLUSIONS

Although we present a small group of cases, our results show how robot-based array insertion is associated with lower impedance and stimulation levels compared to manually inserted arrays.

Objective evaluation, using computed tomography, of round window access for cochlear implantation

OBJECTIVE

The aim of this study was to determine optimal radiological parameters for assessment of the round window approach in cochlear implantation surgery.

MATERIALS AND METHODS

Patients undergoing cochlear implantation at the Department of Otolaryngology in Szczecin, between 2015 and 2022 inclusive, were eligible for the study. Radiological assessments were performed according to eight parameters (seven proposed in the literature) and visibility clinical assessments were made intra-operatively on a scale of 1 to 5 (1 - not visible, 5 - fully visible). Visibility assessments of the round window niche (RWN) and round window membrane (RWM) allowed the difference (RWN minus RWM) to be used as a clinical assessment of the size of the overhang over the round window.

RESULTS

Computed tomography images of 57 ears from 52 patients were analyzed in terms of round window access. The study group included 26 females and 26 males, ranging in age from 1 year to 80 years, with a median age of 41 years. In clinical assessment, round window visibility was rated as 5, after removal of the bone overhang, in 69% of patients. Cochlear access through the round window was achieved in 39 (68%) cases, extended access through the round window in 13 (23%) cases and cochleostomy was performed in 5 (9%) cases. Statistically significant ordinal correlations with round-window access were found using one parameter from the literature (Chen_Angle) and from our proposal (RWM_prediction). From parameters describing the bone overhang of the round window, positive correlations (using Kendall rank tests) were found using parameters from the literature (Sarafraz_OH and Mehanna_OH).

CONCLUSIONS

Radiological measurements describing access to the round window which determine the angle based on the anatomy of the posterior wall of the auditory canal and the position of the facial nerve were found to be of the highest value.

CLINICAL RELEVANCE STATEMENT

In the future, the use of algorithms for computed tomography evaluation and robot-assisted surgery will require parameters for assessing round window access, for surgery planning and choice of electrode. The parameters proposed by various authors are summarized, allowing researchers to assess their usefulness in further clinical practice.

Robotics-Assisted Cochlear Implant Insertion

The degree of intracochlear trauma and force associated with manual electrode insertion may negatively impact cochlear implant (CI) outcomes and preservation of residual acoustic hearing1 ,2 . Robotics-assisted CI insertion systems have recently been developed to overcome human kinematic constraints associated with manual surgical techniques to allow lower force and slower electrode insertions, with the goal of improving performance and hearing preservation outcomes. The iotaSOFT™ (iotaMotion Inc., USA) is an FDA approved robotics-assisted CI insertion tool compatible with modern lateral-wall electrode designs. Pre-clinical studies suggest lower force and less traumatic CI insertions are possible with this system compared to manual insertion techniques3 ,4 . The slower insertion speeds of this system allow more precise control of electrode insertion in response to simultaneous electrocochleography feedback. We demonstrate application of this system with concurrent electrocochleography for hearing preservation cochlear implantation and highlight relevant surgical technique (see Video, Supplemental Digital Content 1 , which demonstrates robotics-assisted CI insertion).

Intraoperative Measurement of Insertion Speed in Cochlear Implant Surgery: A Preliminary Experience with Cochlear SmartNav

OBJECTIVES

The objectives were to present the real-time estimated values of cochlear implant (CI) electrode insertion speed (IS) during intraoperative sessions using the Cochlear Nucleus SmartNav System to assess whether this measure affected CI outcomes and to determine whether real-time feedback assists expert surgeons in achieving slow insertion.

METHODS

The IS was measured in 52 consecutive patients (65 implanted ears) using the CI632 electrode. The IS values were analyzed in relation to procedure repetition over time, NRT ratio, and CI audiological outcomes.

RESULTS

The average IS was 0.64 mm/s (SD = 0.24); minimum and maximum values were 0.23 and 1.24 mm/s, respectively. The IS significantly decreased with each array insertion by the operator (p = 0.006), and the mean decreased by 24% between the first and last third of procedures; however, this reduction fell within the error range of SmartNav for IS (+/-0.48 mm/s). No correlation was found between IS and the NRT ratio (p = 0.51), pure-tone audiometry (PTA) at CI activation (p = 0.506), and PTA (p = 0.94) or word recognition score (p = 0.231) at last evaluation.

CONCLUSIONS

The estimated IS reported by SmartNav did not result in a clinically significant reduction in insertion speed or an improvement in CI hearing outcomes. Real-time feedback of IS could potentially be used for training, but its effectiveness requires confirmation through additional studies and more accurate tools. Implementation of IS assessment in clinical practice will enable comparisons between measurement techniques and between manual and robot-assisted insertions. This will help define the optimal IS range to achieve better cochlear implant (CI) outcomes.

Robotic assistance during cochlear implantation: the rationale for consistent, controlled speed of electrode array insertion

Cochlear implants (CI) have revolutionized the treatment of patients with severe to profound sensory hearing loss by providing a method of bypassing normal hearing to directly stimulate the auditory nerve. A further advance in the field has been the introduction of "hearing preservation" surgery, whereby the CI electrode array (EA) is carefully inserted to spare damage to the delicate anatomy and function of the cochlea. Preserving residual function of the inner ear allows patients to receive maximal benefit from the CI and to combine CI electric stimulation with acoustic hearing, offering improved postoperative speech, hearing, and quality of life outcomes. However, under the current paradigm of implant surgery, where EAs are inserted by hand, the cochlea cannot be reliably spared from damage. Robotics-assisted EA insertion is an emerging technology that may overcome fundamental human kinetic limitations that prevent consistency in achieving steady and slow EA insertion. This review begins by describing the relationship between EA insertion speed and generation of intracochlear forces and pressures. The various mechanisms by which these intracochlear forces can damage the cochlea and lead to worsened postoperative outcomes are discussed. The constraints of manual insertion technique are compared to robotics-assisted methods, followed by an overview of the current and future state of robotics-assisted EA insertion.

Evaluation of Real-Time Intracochlear Electrocochleography for Guiding Cochlear Implant Electrode Array Position

This study evaluates intracochlear electrocochleography (ECochG) for real-time monitoring during cochlear implantation. One aim tested whether adjusting the recording electrode site would help differentiate between atraumatic and traumatic ECochG amplitude decrements. A second aim assessed whether associations between ECochG amplitude decrements and post-operative hearing loss were weaker when considering hearing sensitivity at the ECochG stimulus frequency compared to a broader frequency range. Eleven adult cochlear implant recipients who were candidates for electro-acoustic stimulation participated. Single-frequency (500-Hz) ECochG was performed during cochlear implantation; the amplitude of the first harmonic of the difference waveform was considered. Post-operative hearing preservation at 500 Hz ranged from 0 to 94%. The expected relationship between ECochG amplitude decrements and hearing preservation was observed, though the trend was not statistically significant, and predictions were grossly inaccurate for two participants. Associations did not improve when considering alternative recording sites or hearing sensitivity two octaves above the ECochG stimulus frequency. Intracochlear location of a moving recording electrode is a known confound to real-time interpretation of ECochG amplitude fluctuations, which was illustrated by the strength of the correlation with ECochG amplitude decrements. Multiple factors contribute to ECochG amplitude patterns and to hearing preservation; these results highlight the confounding influence of intracochlear recording electrode location on the ECochG.