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Dhanasingh A, Nielsen SB, Beal F, Schilp S, Hessler R, Jolly C, Hochmair I. Cochlear implant electrode design for safe and effective treatment. Front Neurol 2024; 15:1348439. [PMID: 38756216 PMCID: PMC11096578 DOI: 10.3389/fneur.2024.1348439] [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: 12/02/2023] [Accepted: 04/09/2024] [Indexed: 05/18/2024] Open
Abstract
The optimal placement of a cochlear implant (CI) electrode inside the scala tympani compartment to create an effective electrode-neural interface is the base for a successful CI treatment. The characteristics of an effective electrode design include (a) electrode matching every possible variation in the inner ear size, shape, and anatomy, (b) electrically covering most of the neuronal elements, and (c) preserving intra-cochlear structures, even in non-hearing preservation surgeries. Flexible electrode arrays of various lengths are required to reach an angular insertion depth of 680° to which neuronal cell bodies are angularly distributed and to minimize the rate of electrode scalar deviation. At the time of writing this article, the current scientific evidence indicates that straight lateral wall electrode outperforms perimodiolar electrode by preventing electrode tip fold-over and scalar deviation. Most of the available literature on electrode insertion depth and hearing outcomes supports the practice of physically placing an electrode to cover both the basal and middle turns of the cochlea. This is only achievable with longer straight lateral wall electrodes as single-sized and pre-shaped perimodiolar electrodes have limitations in reaching beyond the basal turn of the cochlea and in offering consistent modiolar hugging placement in every cochlea. For malformed inner ear anatomies that lack a central modiolar trunk, the perimodiolar electrode is not an effective electrode choice. Most of the literature has failed to demonstrate superiority in hearing outcomes when comparing perimodiolar electrodes with straight lateral wall electrodes from single CI manufacturers. In summary, flexible and straight lateral wall electrode type is reported to be gentle to intra-cochlear structures and has the potential to electrically stimulate most of the neuronal elements, which are necessary in bringing full benefit of the CI device to recipients.
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Konrad S, Büchner A, Lenarz T, Paasche G. Impedance development after implantation of hybrid-L24 cochlear implant electrodes. Int J Audiol 2023; 62:1137-1144. [PMID: 36193989 DOI: 10.1080/14992027.2022.2125914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 09/13/2022] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Shorter and thinner electrodes were developed for preserving residual hearing after cochlear implantation by minimising trauma. As trauma is regarded as one of the causes of fibrous tissue formation after implantation, and increase in impedance is considered to be connected to fibrous tissue formation, the aim of the current study was to evaluate impedance development after implantation of Hybrid-L electrodes. DESIGN Impedance values were retrospectively collected from our clinical database and evaluated for all active contacts and basal, middle and apical contacts separately for up to 10 years. STUDY SAMPLES All 137 adult patients received a Hybrid-L electrode and had to be implanted for at least 1 year. RESULTS On average impedances increased to 13 kOhm before first fitting and dropped to 5-7 kOhm under electrical stimulation with lower values measured on apical contacts. Mean values remained stable over years, but variability increased. Values before first fitting were independent of age at implantation whereas lower values were found later in patients of higher age at implantation. CONCLUSION Despite smaller contacts, impedance values after start of electrical stimulation were comparable to published values of Contour electrodes. This might suggest less tissue growth with the Hybrid-L electrode array.
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Affiliation(s)
- Simon Konrad
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Büchner
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Gerrit Paasche
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
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Avasarala VS, Jinka SK, Jeyakumar A. Complications of Cochleostomy Versus Round Window Surgical Approaches: A Systematic Review and Meta-Analysis. Cureus 2022; 14:e25451. [PMID: 35774686 PMCID: PMC9239322 DOI: 10.7759/cureus.25451] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2022] [Indexed: 11/05/2022] Open
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Tejani VD, Kim JS, Oleson JJ, Abbas PJ, Brown CJ, Hansen MR, Gantz BJ. Residual Hair Cell Responses in Electric-Acoustic Stimulation Cochlear Implant Users with Complete Loss of Acoustic Hearing After Implantation. J Assoc Res Otolaryngol 2021; 22:161-176. [PMID: 33538936 DOI: 10.1007/s10162-021-00785-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/03/2021] [Indexed: 11/27/2022] Open
Abstract
Changes in cochlear implant (CI) design and surgical techniques have enabled the preservation of residual acoustic hearing in the implanted ear. While most Nucleus Hybrid L24 CI users retain significant acoustic hearing years after surgery, 6-17 % experience a complete loss of acoustic hearing (Roland et al. Laryngoscope. 126(1):175-81. (2016), Laryngoscope. 128(8):1939-1945 (2018); Scheperle et al. Hear Res. 350:45-57 (2017)). Electrocochleography (ECoG) enables non-invasive monitoring of peripheral auditory function and may provide insight into the pathophysiology of hearing loss. The ECoG response is evoked using an acoustic stimulus and includes contributions from the hair cells (cochlear microphonic-CM) as well as the auditory nerve (auditory nerve neurophonic-ANN). Seven Hybrid L24 CI users with complete loss of residual hearing months after surgery underwent ECoG measures before and after loss of hearing. While significant reductions in CMs were evident after hearing loss, all participants had measurable CMs despite having no measurable acoustic hearing. None retained measurable ANNs. Given histological data suggesting stable hair cell and neural counts after hearing loss (e.g., Quesnel et al. Hear Res. 333:225-234. (2016)), the loss of ECoG and audiometric hearing may reflect reduced synaptic input. This is consistent with the theory that residual CM responses coupled with little to no ANN responses reflect a "disconnect" between hair cells and auditory nerve fibers (Fontenot et al. Ear Hear. 40(3):577-591. 2019). This "disconnection" may prevent proper encoding of auditory stimulation at higher auditory pathways, leading to a lack of audiometric responses, even in the presence of viable cochlear hair cells.
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Affiliation(s)
- Viral D Tejani
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA. .,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA.
| | - Jeong-Seo Kim
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA
| | - Jacob J Oleson
- Department of Biostatistics, University of Iowa, Iowa City, IA, USA
| | - Paul J Abbas
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA
| | - Carolyn J Brown
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.,Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Bruce J Gantz
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.,Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
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Impact of stimulus frequency and recording electrode on electrocochleography in Hybrid cochlear implant users. Hear Res 2019; 384:107815. [PMID: 31678892 DOI: 10.1016/j.heares.2019.107815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 10/02/2019] [Accepted: 10/09/2019] [Indexed: 11/21/2022]
Abstract
This report explores the impact of recording electrode position and stimulus frequency on intracochlear electrocochleography (ECoG) responses recorded from six Nucleus L24 Hybrid CI users. Acoustic tone bursts (250 Hz, 500 Hz, 750 Hz, and 1000 Hz) were presented to the implanted ear via an insert earphone. Recordings were obtained from intracochlear electrodes 6 (most basal), 8, 10, 12, 14, 16, 18, 20, and 22 (most apical). Responses to condensation and rarefaction stimuli were subtracted from one another to emphasize hair cell responses (CM/DIF) and added to one another to emphasize neural responses (ANN/SUM). For a fixed stimulus frequency, the CM/DIF and ANN/SUM magnitudes increased as the recording electrode moved apically. For a fixed recording electrode, as the stimulus frequency was lowered, response magnitudes increased. The CM/DIF and ANN/SUM response phase were generally stable across recording electrodes, although substantial phase shifts were noted for a few conditions. Given the recent interest in ECoG for assessing peripheral auditory function in CI users, the impact of stimulus frequency and recording electrode position on response magnitude should be considered. Results suggest optimal ECoG responses are obtained using the most apical recording electrode and a low frequency acoustic stimulus (250 Hz or 500 Hz).
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Landry TG, Earle G, Brown JA, Bance ML. Real-time intracochlear imaging of automated cochlear implant insertions in whole decalcified cadaver cochleas using ultrasound. Cochlear Implants Int 2018; 19:255-267. [DOI: 10.1080/14670100.2018.1460024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Thomas G. Landry
- Division of Otolaryngology, Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Guy Earle
- Division of Otolaryngology, Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
| | - Jeremy A. Brown
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Manohar L. Bance
- Department of Neuroscience, University of Cambridge, Cambridge, UK
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Dhanasingh A, Jolly C. An overview of cochlear implant electrode array designs. Hear Res 2017; 356:93-103. [DOI: 10.1016/j.heares.2017.10.005] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/26/2017] [Accepted: 10/13/2017] [Indexed: 11/28/2022]
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Cochlear Implant Electrode Localization Using an Ultra-High Resolution Scan Mode on Conventional 64-Slice and New Generation 192-Slice Multi-Detector Computed Tomography. Otol Neurotol 2017; 38:978-984. [DOI: 10.1097/mao.0000000000001463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Insertion forces and intracochlear trauma in temporal bone specimens implanted with a straight atraumatic electrode array. Eur Arch Otorhinolaryngol 2017; 274:2131-2140. [PMID: 28238160 DOI: 10.1007/s00405-017-4485-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
The aim of the study was to evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones, and post-implantation histologic evaluation of the samples to determine whether violation of intracochlear structures is related to insertion forces. In order to minimize intracochlear trauma and preserve residual hearing during cochlear implantation, knowledge of the insertion forces is necessary. Ten fresh frozen human temporal bones were prepared with canal wall down mastoidectomy. All samples were mounted on a one-axis force sensor. Insertion of a 16-mm straight atraumatic electrode was performed from different angles to induce "traumatic" insertion. Histologic evaluation was performed in order to evaluate intracochlear trauma. In 4 of 10 samples, dislocation of the electrode into scala vestibuli was observed. The mean insertion force for all 10 procedures was 0.003 ± 0.005 N. Insertion forces measured around the site of dislocation to scala vestibuli in 3 of 4 samples were significantly higher than insertion forces at the same location of the cochleae measured in samples without trauma (p < 0.04). Mean force during the whole insertion process of the straight atraumatic electrode is lower than reported by other studies using longer electrodes. Based on our study, insertion forces leading to basilar membrane trauma may be lower than the previously reported direct rupture forces.
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Insertion trauma of a cochlear implant electrode array with Nitinol inlay. Eur Arch Otorhinolaryngol 2016; 273:3573-3585. [PMID: 26961519 DOI: 10.1007/s00405-016-3955-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 02/26/2016] [Indexed: 10/22/2022]
Abstract
The integration of a shape memory actuator is a potential mechanism to achieve a consistent perimodiolar position after electrode insertion during cochlear implant surgery. After warming up, and therefore activation of the shape memory effect, the electrode array will change from a straight configuration into a spiral shaped one leading to a final position close to the modiolus. The aim of this study was to investigate whether the integration of an additional thin wire (referred to as an "inlay") made of Nitinol, a well-established shape memory alloy, in a conventional hearing preservation electrode array will affect the insertion behaviour in terms of increased risk of insertion trauma. Six conventional Hybrid-L electrode arrays (Cochlear Ltd., Sydney, Australia) were modified to incorporate a wire inlay made of Nitinol. The diameter of the wires was 100 µm with a tapered tip region. Electrodes were inserted into human temporal bone specimens using a standard surgical approach. After insertion and embedding in epoxy resin, histological sections were prepared to evaluate insertion trauma. Insertion was straightforward and no difficulties were observed. The addition of a shape memory wire, thin but also strong enough to curl the electrode array, does not result in histologically detectable insertion trauma. Atraumatic insertion seems possible.
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Frisch CD, Carlson ML, Lane JI, Driscoll CLW. Evaluation of a new mid-scala cochlear implant electrode using microcomputed tomography. Laryngoscope 2015; 125:2778-83. [DOI: 10.1002/lary.25347] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2015] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - John I. Lane
- Department of Radiology; Mayo Clinic; Rochester Minnesota U.S.A
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Szyfter W, Wróbel M, Karlik M, Borucki L, Stieler M, Gibasiewicz R, Gawęcki W, Sekula A. Observations on hearing preservation in patients with hybrid-L electrode implanted at Poznan University of Medical Sciences in Poland. Eur Arch Otorhinolaryngol 2012; 270:2637-40. [PMID: 23223855 PMCID: PMC3758514 DOI: 10.1007/s00405-012-2263-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 11/02/2012] [Indexed: 11/10/2022]
Abstract
The objective of the paper is to evaluate the hearing preservation rate in patients with high frequency hearing loss, treated with Cochlear Nucleus Freedom Hybrid-L implant in the Otolaryngology Department, Poznan University of Medical Sciences in Poland. Study was designed as the retrospective analysis. Twenty-one patients were operated and implanted with Nucleus Freedom Hybrid-L implant. Pure tone thresholds were recorded prior to the surgery and at the time of speech processor switch-on. Patients were subdivided into two groups with respect to their PTA thresholds: group A—classic indications and group B—extended indications. Average PTA for three frequencies (250, 500, 1,000 Hz) were calculated for each patient pre- and postoperatively. In the group of 21 implanted patients in 17 cases we have observed preservation of hearing (12 patients from group A, 5 patients from group B) with a mean value of 13.1 dB. In 4 out of 21 patients deafness on the implanted ear was noted. Our results clearly indicate that with standard procedure hearing preservation can be obtained in majority of patients. Hearing preservation was not achieved in 19 %, but owing to design of the electrode of the Cochlear Nucleus Hybrid-L that enables to work as CI platform alone, in patients who lost their hearing after surgery re-implantations were not required. This proves that EAS is a safe and reliable method to help patients with specific type of hearing loss.
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Affiliation(s)
- Witold Szyfter
- Department of Otolaryngology and Oncological Laryngology, Poznan University of Medical Sciences, Ul. Przybyszewskiego 49, 60-355 Poznan, Poland
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Cushing SL, Daly MJ, Treaba CG, Chan H, Irish JC, Blaser S, Gordon KA, Papsin BC. High-resolution cone-beam computed tomography: a potential tool to improve atraumatic electrode design and position. Acta Otolaryngol 2012; 132:361-8. [PMID: 22235960 DOI: 10.3109/00016489.2011.644805] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSIONS Flat-panel cone-beam computed tomography (CBCT) is able to assess the trajectory of the implanted cochlear implant (CI) array. This is essential to determine specific effects of electrode design and surgical innovations on outcomes in cochlear implantation. CBCT is a non-invasive approach yielding similar data to histopathological analyses, with encouraging potential for use in surgical, clinical and research settings. OBJECTIVES To examine the fidelity of CBCT imaging and custom 3D visualization in characterizing CI insertion in comparison to gold standard, histopathological examination. METHODS Eleven human temporal bones were implanted with the 'Straight Research Array' (SRA). Post-insertion, they were imaged with a prototype mobile C-arm for intraoperative CBCT. Post-acquisition processing of low-dose CBCT images produced high-resolution 3D volumes with sub-millimetre spatial resolution (isotropic 0.2 mm(3) voxels). The bones were resin impregnated and sectioned for light microscopic examination. Dimensional electrode characteristics visible in section images were compared with corresponding CBCT images by independent observers. RESULTS Overall, CBCT demonstrated adequate resolution to detect: 1) scala implanted; 2) kinking; 3) number of intracochlear contacts; 4) appropriate ascension of the array; and overall confirms ideal insertion. CBCT did not demonstrate adequate resolution to detect reversal of electrode contacts or basilar membrane rupture.
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Affiliation(s)
- Sharon L Cushing
- Archie's Cochlear Implant Laboratory, Hospital for Sick Children, Toronto, ON, Canada.
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