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Asfour L, Risi F, Treaba C, Kirk J, Roland Thomas J. Evaluation of a Slim Modiolar Electrode Array: A Temporal Bone Study. Otol Neurotol 2024; 45:870-877. [PMID: 39142309 DOI: 10.1097/mao.0000000000004253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
HYPOTHESIS Evaluation of the Slim Modiolar (SM) electrode in temporal bones (TB) will elucidate the electrode's insertion outcomes. BACKGROUND The SM electrode was designed for atraumatic insertion into the scala tympani, for ideal perimodiolar positioning and with a smaller caliber to minimize interference with cochlear biological processes. METHODS The SM electrode was inserted into TBs via a cochleostomy. First, the axial force of insertion was measured. Next, TBs were inserted under fluoroscopy to study insertion dynamics, followed by histologic evaluation of electrode placement and cochlear trauma. A subset of TBs were inserted with the Contour Advance (CA) electrode for comparison. RESULTS Sixteen of 22 insertions performed to measure the axial force of insertion had flat or near zero insertion force profiles. Six insertions had increased insertion forces, which were attributed to improper sheath depth before electrode insertion. Under real-time fluoroscopy, 23 of 25 TBs had uneventful insertion and good perimodiolar placement. There was 1 scala vestibuli insertion due to suboptimal cochleostomy position and 1 tip roll over related to premature electrode deployment. When compared with the CA electrode, 14 of 15 insertions with the SM electrode resulted in a more perimodiolar electrode position. No evidence of trauma was found in histologic evaluation of the 24 TBs with scala tympani insertions. CONCLUSION TB evaluation revealed that the SM electrode exerts minimal insertion forces on cochlear structures, produces no histologic evidence of trauma, and reliably assumes the perimodiolar position. Nonstandard cochleostomy location, improper sheath insertion depth, or premature deployment of the electrode may lead to suboptimal outcomes.
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Affiliation(s)
- Leena Asfour
- Department of Otolaryngology, New York University School of Medicine, New York, U.S.A
| | | | | | | | - J Roland Thomas
- Department of Otolaryngology, New York University School of Medicine, New York, U.S.A
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Meuser M, Schwitzer S, Thiele M, Boyle P, Ernst A, Basta D. Intra-Cochlear Electrode Position Impacts the Preservation of Residual Hearing in an Animal Model of Cochlear Implant Surgery. Audiol Neurootol 2024:1-11. [PMID: 38981457 DOI: 10.1159/000540266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 07/07/2024] [Indexed: 07/11/2024] Open
Abstract
INTRODUCTION Preservation of residual hearing after cochlear implantation remains challenging. There are several approaches to preserve residual hearing, but the configuration of the implant electrode array seems to play a major role. Lateral wall electrode arrays are seemingly more favorable in this context. To date, there are no experimental data available which correlate the spatial electrode position in the scala tympani with the extent of hearing preservation. METHODS Based on micro-computed tomography (µCT) imaging data, this study analyses the exact position of a pure silicone electrode array inserted into the cochlea of four guinea pigs. Array position data were correlated with the extent of hearing loss after implantation, measured using auditory brainstem measurements in the frequency range of the area occupied by the electrode array area as well as apical to the array. RESULTS The use of pure silicone arrays without electrodes resulted in artifact-free, high-resolution µCT images that allowed precise determination of the arrays' positions within the scala tympani. The electrode arrays' locations ranged from peri-modiolar to an anti-modiolar. These revealed a correlation of a lower postoperative hearing loss with a higher spatial proximity to the lateral wall. This correlation was found in the low-frequency range only. A significant correlation between the inter-individual differences in the diameter of the scala tympani and the postoperative hearing loss could not be observed. CONCLUSION This study demonstrates the importance of the intra-cochlear electrode array's position for the preservation of residual hearing. The advantage of such an electrode array's position approximated to the lateral wall suggests, at least for this type of electrode array applied in the guinea pig, it would be advantageous in the preservation of residual hearing for the apical part of the cochlea, beyond the area occupied by the electrode array.
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Affiliation(s)
- Max Meuser
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Susanne Schwitzer
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Mario Thiele
- Julius Wolff Institute, Center for Musculoskeletal Biomechanics and Regeneration, Charité Medical School, University of Berlin, Berlin, Germany
| | - Patrick Boyle
- Advanced Bionics GmbH, European Research Centre, Hanover, Germany
| | - Arne Ernst
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Dietmar Basta
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
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Hrnčiřík F, Nagy L, Grimes HL, Iftikhar H, Muzaffar J, Bance M. Impact of Insertion Speed, Depth, and Robotic Assistance on Cochlear Implant Insertion Forces and Intracochlear Pressure: A Scoping Review. SENSORS (BASEL, SWITZERLAND) 2024; 24:3307. [PMID: 38894099 PMCID: PMC11174543 DOI: 10.3390/s24113307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 06/21/2024]
Abstract
Cochlear implants are crucial for addressing severe-to-profound hearing loss, with the success of the procedure requiring careful electrode placement. This scoping review synthesizes the findings from 125 studies examining the factors influencing insertion forces (IFs) and intracochlear pressure (IP), which are crucial for optimizing implantation techniques and enhancing patient outcomes. The review highlights the impact of variables, including insertion depth, speed, and the use of robotic assistance on IFs and IP. Results indicate that higher insertion speeds generally increase IFs and IP in artificial models, a pattern not consistently observed in cadaveric studies due to variations in methodology and sample size. The study also explores the observed minimal impact of robotic assistance on reducing IFs compared to manual methods. Importantly, this review underscores the need for a standardized approach in cochlear implant research to address inconsistencies and improve clinical practices aimed at preserving hearing during implantation.
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Affiliation(s)
- Filip Hrnčiřík
- Cambridge Hearing Group, Cambridge CB2 7EF, UK; (F.H.)
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Leo Nagy
- Clinical School, University of Cambridge, Cambridge CB2 0QQ, UK
| | | | - Haissan Iftikhar
- Department of Otolaryngology, University Hospitals Birmingham, Birmingham B15 2TT, UK
| | - Jameel Muzaffar
- Cambridge Hearing Group, Cambridge CB2 7EF, UK; (F.H.)
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK
- Department of Otolaryngology, University Hospitals Birmingham, Birmingham B15 2TT, UK
| | - Manohar Bance
- Cambridge Hearing Group, Cambridge CB2 7EF, UK; (F.H.)
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK
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Zagabathuni A, Padi KK, Kameswaran M, Subramani K. Development of Automated Tool for Electrode Array Insertion and its Study on Intracochlear Pressure. Laryngoscope 2024; 134:1388-1395. [PMID: 37584398 DOI: 10.1002/lary.30966] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 06/05/2023] [Accepted: 07/14/2023] [Indexed: 08/17/2023]
Abstract
Cochlear implantation is the most successful approach for people with profound sensorineural hearing loss. Manual insertion of the electrode array may result in damaging the soft tissue structures and basilar membrane. An automated electrode array insertion device is reported to be less traumatic in cochlear implant surgery. OBJECTIVES The present work develops a simple, reliable, and compact device for automatically inserting the electrode array during cochlear implantation and test the device to observe intracochlear pressure during simulated electrode insertion. METHODS The device actuates the electrode array by a roller mechanism. For testing the automated device, a straight cochlea having the dimension of the scala tympani and a model electrode is developed using a 3D printer. A pressure sensor is utilized to observe the pressure change at different insertional conditions. RESULTS The electrode is inserted into a prototype cochlea at different speeds without any pause, and it is noticed that the pressure is increased with the depth of insertion of the electrode irrespective of the speed of electrode insertion. The rate of pressure change is observed to be increased exponentially with the speed of insertion. CONCLUSION At an insertion speed of 0.15 mm/s, the peak pressure is observed to be 133 Pa, which can be further evaluated in anatomical models for clinical scenarios. LEVEL OF EVIDENCE N/A Laryngoscope, 134:1388-1395, 2024.
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Affiliation(s)
- Aparna Zagabathuni
- School of Materials Science and Engineering, National Institute of Technology Calicut, Calicut, India
| | - Kishore Kumar Padi
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati, India
| | | | - Kanagaraj Subramani
- Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati, India
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Kashani RG, Henslee A, Nelson RF, Hansen MR. Robotic assistance during cochlear implantation: the rationale for consistent, controlled speed of electrode array insertion. Front Neurol 2024; 15:1335994. [PMID: 38318440 PMCID: PMC10839068 DOI: 10.3389/fneur.2024.1335994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 01/05/2024] [Indexed: 02/07/2024] Open
Abstract
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.
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Affiliation(s)
- Rustin G. Kashani
- Department of Otolaryngology – Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
| | | | | | - Marlan R. Hansen
- Department of Otolaryngology – Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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Starovoyt A, Shaheen E, Putzeys T, Kerckhofs G, Politis C, Wouters J, Verhaert N. Anatomically and mechanically accurate scala tympani model for electrode insertion studies. Hear Res 2023; 430:108707. [PMID: 36773540 DOI: 10.1016/j.heares.2023.108707] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 11/25/2022] [Accepted: 01/24/2023] [Indexed: 01/26/2023]
Abstract
The risk of insertion trauma in cochlear implantation is determined by the interplay between individual cochlear anatomy and electrode insertion mechanics. Whereas patient anatomy cannot be changed, new surgical techniques, devices for cochlear monitoring, drugs, and electrode array designs are continuously being developed and tested, to optimize the insertion mechanics and prevent trauma. Preclinical testing of these developments is a crucial step in feasibility testing and optimization for clinical application. Human cadaveric specimens allow for the best simulation of an intraoperative setting. However, their availability is limited and it is not possible to conduct repeated, controlled experiments on the same sample. A variety of artificial cochlear models have been developed for electrode insertion studies, but none of them were both anatomically and mechanically representative for surgical insertion into an individual cochlea. In this study, we developed anatomically representative models of the scala tympani for surgical insertion through the round window, based on microCT images of individual human cochleae. The models were produced in transparent material using commonly-available 3D printing technology at a desired scale. The anatomical and mechanical accuracy of the produced models was validated by comparison with human cadaveric cochleae. Mechanical evaluation was performed by recording insertion forces, counting the number of inserted electrodes and grading tactile feedback during manual insertion of a straight electrode by experienced cochlear implant surgeons. Our results demonstrated that the developed models were highly representative for the anatomy of the original cochleae and for the insertion mechanics in human cadaveric cochleae. The individual anatomy of the produced models had a significant impact on the insertion mechanics. The described models have a promising potential to accelerate preclinical development and testing of atraumatic insertion techniques, reducing the need for human cadaveric material. In addition, realistic models of the cochlea can be used for surgical training and preoperative planning of patient-tailored cochlear implantation surgery.
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Affiliation(s)
- Anastasiya Starovoyt
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Eman Shaheen
- OMFS IMPATH Research Group, Department of Imaging and Pathology, KU Leuven, University of Leuven, Leuven, Belgium; Department of Oral and Maxillofacial Surgery, UZ Leuven, University Hospitals Leuven, Leuven, Belgium
| | - Tristan Putzeys
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, University of Leuven, Leuven, Belgium
| | - Greet Kerckhofs
- Biomechanics lab, Institute of Mechanics, Materials, and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Department of Materials Engineering, KU Leuven, University of Leuven, Leuven, Belgium; IREC, Institute of Experimental and Clinical Research, UCLouvain, Woluwé-Saint-Lambert, Belgium; Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, University of Leuven, Leuven, Belgium
| | - Constantinus Politis
- OMFS IMPATH Research Group, Department of Imaging and Pathology, KU Leuven, University of Leuven, Leuven, Belgium; Department of Oral and Maxillofacial Surgery, UZ Leuven, University Hospitals Leuven, Leuven, Belgium
| | - Jan Wouters
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Nicolas Verhaert
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Department of Otorhinolaryngology, Head and Neck Surgery, UZ Leuven, University Hospitals of Leuven, Leuven, Belgium.
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Human cochlear microstructures at risk of electrode insertion trauma, elucidated in 3D with contrast-enhanced microCT. Sci Rep 2023; 13:2191. [PMID: 36750646 PMCID: PMC9905077 DOI: 10.1038/s41598-023-29401-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Cochlear implant restores hearing loss through electrical stimulation of the hearing nerve from within the cochlea. Unfortunately, surgical implantation of this neuroprosthesis often traumatizes delicate intracochlear structures, resulting in loss of residual hearing and compromising hearing in noisy environments and appreciation of music. To avoid cochlear trauma, insertion techniques and devices have to be adjusted to the cochlear microanatomy. However, existing techniques were unable to achieve a representative visualization of the human cochlea: classical histology damages the tissues and lacks 3D perspective; standard microCT fails to resolve the cochlear soft tissues; and previously used X-ray contrast-enhancing staining agents are destructive. In this study, we overcame these limitations by performing contrast-enhanced microCT imaging (CECT) with a novel polyoxometalate staining agent Hf-WD POM. With Hf-WD POM-based CECT, we achieved nondestructive, high-resolution, simultaneous, 3D visualization of the mineralized and soft microstructures in fresh-frozen human cochleae. This enabled quantitative analysis of the true intracochlear dimensions and led to anatomical discoveries, concerning surgically-relevant microstructures: the round window membrane, the Rosenthal's canal and the secondary spiral lamina. Furthermore, we demonstrated that Hf-WD POM-based CECT enables quantitative assessment of these structures as well as their trauma.
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