Radiological evaluation of a new straight electrode array compared to its precursors

Abstract Objective The aim of this study is to examine electrode array coverage, scalar position and dislocation rate in straight electrode arrays with special focus on a new electrode array with 26 mm in lengths. Study design Retrospective study. Setting Tertiary academic center. Patients 201 ears implanted between 2013 and 2019. Main outcome measures We conducted a comparative analysis of patients implanted with lateral wall electrode arrays of different lengths (F24 = MED-EL Flex24, F26 = MED-EL Flex26, F28 = MED-EL Flex28 and F31.5 = MED-EL FlexSoft). Cone beam computed tomography was used to determine electrode array position (scala tympani (ST) versus scala vestibuli (SV), intracochlear dislocation, position of dislocation and insertion angle). Results Study groups show no significant differences regarding cochlear size which excludes influences by cochlear morphology. As expected, the F24 showed significant shorter insertion angles compared to the longer electrode arrays. The F26 electrode array showed no signs of dislocation or SV insertion. The electrode array with the highest rate of ST dislocations was the F31.5 (26.3%). The electrode array with the highest rates of SV insertions was the F28 (5.75%). Most of the included electrode arrays dislocate between 320° and 360° (mean: 346.4°; range from 166° to 502°). Conclusion The shorter F24 and the new straight electrode array F26 show less or no signs of scalar dislocation, neither for round window nor for cochleostomy insertion than the longer F28 and the F31.5 array. As expected, the cochlear coverage is increasing with length of the electrode array itself but with growing risk for scalar dislocation and with the highest rates of dislocation for the longest electrode array F31.5. Position of intracochlear dislocation is in the apical cochlear part in the included lateral wall electrode arrays.

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Incidence of Complete Insertion in Cochlear Implant Recipients of Long Lateral Wall Arrays

Otolaryngology ◽

10.1177/0194599820987456 ◽

2021 ◽

pp. 019459982098745

Author(s):

Michael W. Canfarotta ◽

Margaret T. Dillon ◽

Kevin D. Brown ◽

Harold C. Pillsbury ◽

Matthew M. Dedmon ◽

...

Keyword(s):

Cochlear Implant ◽

Electrode Array ◽

Lateral Wall ◽

Electrode Arrays ◽

Tertiary Referral ◽

Insertion Depth ◽

Future Studies ◽

Tertiary Referral Center ◽

Cochlear Duct Length ◽

Cochlear Morphology

Objective High rates of partial insertion have been reported for cochlear implant (CI) recipients of long lateral wall electrode arrays, presumably caused by resistance encountered during insertion due to cochlear morphology. With recent advances in long-electrode array design, we sought to investigate (1) the incidence of complete insertions among patients implanted with 31.5-mm flexible arrays and (2) whether complete insertion is limited by cochlear duct length (CDL). Study Design Retrospective review. Setting Tertiary referral center. Methods Fifty-one adult CI recipients implanted with 31.5-mm flexible lateral wall arrays underwent postoperative computed tomography to determine the rate of complete insertion, defined as all contacts being intracochlear. CDL and angular insertion depth (AID) were compared between complete and partial insertion cohorts. Results Most cases had a complete insertion (96.1%, n = 49). Among the complete insertion cohort, the median CDL was 33.6 mm (range, 30.3-37.9 mm), and median AID was 641° (range, 533-751°). Two cases of partial insertion had relatively short CDL (31.8 mm and 32.3 mm) and shallow AID (542° and 575°). Relatively shallow AID for the 2 cases of partial insertion fails to support the idea that CDL alone prevents a complete insertion. Conclusion Complete insertion of a 31.5-mm flexible array is feasible in most cases and does not appear to be limited by the range of CDL observed in this cohort. Future studies are needed to estimate other variations in cochlear morphology that could predict resistance and failure to achieve complete insertion with long arrays.

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Electrode array design determines scalar position, dislocation rate and angle and postoperative speech perception

European Archives of Oto-Rhino-Laryngology ◽

10.1007/s00405-021-07160-2 ◽

2021 ◽

Author(s):

Manuel Christoph Ketterer ◽

Antje Aschendorff ◽

Susan Arndt ◽

Rainer Beck

Keyword(s):

Speech Perception ◽

Significant Influence ◽

Electrode Array ◽

Dislocation Rate ◽

Speech Discrimination ◽

Electrode Arrays ◽

Insertion Depth ◽

Array Design ◽

Cochlear Morphology ◽

Array Position

Abstract Purpose The aim of this study is to examine the scalar dislocation rate in straight and perimodiolar electrode arrays in relation to cochlear morphology. Furthermore, we aim to analyze the specific dislocation point of electrode arrays depending on their design and shape and to correlate these results to postoperative speech perception. Methods We conducted a comparative analysis of patients (ears: n = 495) implanted between 2013 and 2018 with inserted perimodiolar or straight electrode arrays from Cochlear™ or MED-EL. CBCT (cone beam computed tomography) was used to determine electrode array position (scalar insertion, intra-cochlear dislocation, point of dislocation and angular insertion depth). Furthermore, cochlear morphology was measured. The postoperative speech discrimination was compared regarding electrode array dislocation, primary scalar insertion and angular insertion depth. Results The electrode array with the highest rate of primary SV insertions was the CA; the electrode array with the highest rate of dislocations out of ST was the FlexSoft. We did not find significantly higher dislocation rates in cochleostomy-inserted arrays. The angle of dislocation was electrode array design-specific. A multivariate nonparametric analysis revealed that the dislocation of the electrode array has no significant influence on postoperative speech perception. Nevertheless, increasing angular insertion depth significantly reduced postoperative speech perception for monosyllables. Conclusion This study demonstrates the significant influence of electrode array design on scalar location, dislocation and the angle of dislocation itself. Straight and perimodiolar electrode arrays differ from each other regarding both the rate and place of dislocation. Insertion via cochleostomy does not lead to increased dislocation rates in any of the included electrode arrays. Furthermore, speech perception is significantly negatively influenced by angular insertion depth.

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Electrode design and insertional depth-dependent intra-cochlear pressure changes: a model experiment

The Journal of Laryngology & Otology ◽

10.1017/s0022215117002195 ◽

2017 ◽

Vol 132 (3) ◽

pp. 224-229 ◽

Cited By ~ 3

Author(s):

P Mittmann ◽

A Ernst ◽

I Todt

Keyword(s):

Cochlear Implant ◽

Fluid Pressure ◽

Electrode Array ◽

Lateral Wall ◽

Peak Frequency ◽

Peak Amplitude ◽

Residual Hearing ◽

Electrode Arrays ◽

Pressure Peak ◽

Pressure Changes

AbstractBackground:Preservation of residual hearing is one of the major goals in modern cochlear implant surgery. Intra-cochlear fluid pressure changes influence residual hearing, and should be kept low before, during and after cochlear implant insertion.Methods:Experiments were performed in an artificial cochlear model. A pressure sensor was inserted in the apical part. Five insertions were performed on two electrode arrays. Each insertion was divided into three parts, and statistically evaluated in terms of pressure peak frequency and pressure peak amplitude.Results:The peak frequency over each third part of the electrode increased in both electrode arrays. A slight increase was seen in peak amplitude in the lateral wall electrode array, but not in the midscalar electrode array. Significant differences were found in the first third of both electrode arrays.Conclusion:The midscalar and lateral wall electrode arrays have different intra-cochlear fluid pressure changes associated with intra-cochlear placement, electrode characteristics and insertion.

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The influence of cochlear morphology on the final electrode array position

European Archives of Oto-Rhino-Laryngology ◽

10.1007/s00405-017-4842-y ◽

2017 ◽

Vol 275 (2) ◽

pp. 385-394 ◽

Cited By ~ 12

Author(s):

M. C. Ketterer ◽

A. Aschendorff ◽

S. Arndt ◽

F. Hassepass ◽

T. Wesarg ◽

...

Keyword(s):

Electrode Array ◽

Cochlear Morphology ◽

Array Position

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Intraoperative use of cone-beam computed tomography in a cadaveric ossified cochlea model

Otolaryngology ◽

10.1016/j.otohns.2008.12.046 ◽

2009 ◽

Vol 140 (5) ◽

pp. 697-702 ◽

Cited By ~ 32

Author(s):

Emma Barker ◽

Keith Trimble ◽

Harley Chan ◽

James Ramsden ◽

Sajendra Nithiananthan ◽

...

Keyword(s):

Computed Tomography ◽

Temporal Bone ◽

Cone Beam Computed Tomography ◽

Intraoperative Imaging ◽

Electrode Array ◽

Cone Beam ◽

Electrode Placement ◽

Electrode Arrays ◽

Labyrinthitis Ossificans ◽

Conventional Ct

Objectives: To describe a cadaveric temporal bone model of labyrinthitis ossificans and investigate the utility of intraoperative cone-beam computed tomography (CBCT) in the facilitating cochlear implantation. Design: Cadaveric temporal bone study. Methods: Five cadaveric heads had cement introduced into the 10 cochleas. CBCT and a conventional CT scan were compared to assess the extent of cochlear obliteration. The cement was drilled-out (under CBCT guidance, if required) and cochlear implant electrode arrays (from 3 different manufacturers) inserted. Results: CBCT images demonstrated temporal bone anatomy and the extent of cochlear obliteration as clearly as conventional CT in all cases. Intraoperative CBCT guided drilling and facilitated electrode placement in two of five heads (3 of 10 ears). Streak-artifact from the electrodes of two devices partially obscured image clarity. Conclusions: The obliterated cochlear model reproduced a disease-ossified cochlear both radiographically and surgically. CBCT is useful for intraoperative imaging to facilitate electrode array placement in the obliterated or congenitally abnormal cochlea.

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CT-Derived Estimation of Cochlear Morphology and Electrode Array Position in Relation to Word Recognition in Nucleus-22 Recipients

Journal of the Association for Research in Otolaryngology ◽

10.1007/s101620020013 ◽

2002 ◽

Vol 3 (3) ◽

pp. 332-350 ◽

Cited By ~ 138

Author(s):

Margaret W. Skinner ◽

Darlene R. Ketten ◽

Laura K. Holden ◽

Gary W. Harding ◽

Peter G. Smith ◽

...

Keyword(s):

Word Recognition ◽

Electrode Array ◽

Cochlear Morphology ◽

Array Position

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Cochlearis implantátumok különböző, előre görbített elektródasorainak elhelyezkedése a cochlea tengelyéhez viszonyítva. Radiológiai vizsgálat a perimodiolaritás mértékének megállapítására

Orvosi Hetilap ◽

10.1556/650.2019.31457 ◽

2019 ◽

Vol 160 (31) ◽

pp. 1216-1222

Author(s):

Ádám Perényi ◽

Roland Nagy ◽

Balázs Dimák ◽

Miklós Csanády ◽

József Jóri ◽

...

Keyword(s):

Energy Consumption ◽

Ganglion Cells ◽

Round Window ◽

Electrode Array ◽

Neural Responses ◽

Electrode Arrays ◽

Performance Abilities ◽

Length Width ◽

Electrophysiological Result ◽

The Mean

Abstract: Introduction: The cochlear implants vary in electrodes in terms of length, width and proximity to the modiolus. The precurved electrode arrays could be placed closer to the modiolus and the ganglion cells compared to straight electrodes. The two types of electrode arrays provide different electrophysiological characteristics; however, proximity to the modiolus may lead to better hearing performance. Aim: To investigate our preliminary electrophysiological results that suggest that the Slim Modiolar (SM) electrode array has the potential to elicit similar neural responses as the thicker perimodiolar (Contour Advance, CA) electrode from the same generation of implants. Method: Subjects that were implanted either with CA or SM electrodes were enrolled, 54 consecutive subjects in each group. All electrodes were introduced into the cochlea via the round window. The diameter of the largest turn of the electrode arrays within the cochlea was measured through postoperative radiography. The energy consumption parameters were estimated 2 months after implantation. Results: The mean of the largest turns of the arrays within the cochlea was 4.2 ± 0.5 mm in the SM group and 4.9 ± 1.1 mm in the CA group. ‘Auto power’ was 44.81 ± 5.05% and 50.85 ± 8.35% with SM and CA, respectively. Estimated energy consumption was lower with SM. The differences were statistically significant. Conclusion: Our measurements for a large cohort in each group suggest that the SM electrode array takes a significantly closer position to the modiolus than the CA. This finding supports our earlier electrophysiological result and indicates better performance abilities. Orv Hetil. 2019; 160(31): 1216–1222.

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The Use of a Robot to Insert an Electrode Array of Cochlear Implants in the Cochlea: A Feasibility Study and Preliminary Results

Audiology and Neurotology ◽

10.1159/000513509 ◽

2021 ◽

pp. 1-7

Author(s):

Sébastien Barriat ◽

Nicolas Peigneux ◽

Unal Duran ◽

Severine Camby ◽

Philippe P. Lefebvre

Keyword(s):

Inner Ear ◽

Cochlear Implants ◽

Pure Tone ◽

Cone Beam Ct ◽

Surgical Techniques ◽

Electrode Array ◽

Pure Tone Audiometry ◽

Cone Beam ◽

Middle Ear Surgery ◽

Electrode Arrays

Introduction: Cochlear implants (CIs) are commonly used for the rehabilitation of profound bilateral hearing loss. However, patients with substantial residual acoustic hearing are potential CI candidates. Because of both improvements in technology and advancements in surgical techniques, it may be possible to preserve hearing to some extent. For more than a decade, it has been suggested that robots are used to perform middle ear surgery. We evaluated the use of the RobOtol® otologic robot specifically to insert CI electrodes into the inner ear. Methods: CI surgery with the conventional approach was performed under general anesthesia. The MED-El Flex 24-electrode array was inserted using RobOtol®. Video recordings were used to calculate the speed of insertion. The positions of the electrodes were evaluated using a cone beam CT. All subjects underwent pure-tone audiometry tests before and after surgery, and the pure-tone average (PTA) was calculated from 250 to 4,000 Hz. Results: The robot inserted implants in 5 patients, and complete insertion of the electrode array was achieved. The speed of insertion of the electrode array was 0.88 ± 0.12 mm/s. The mean loss of the PTA for 5 frequencies (250, 500, 1,000, 2,000, and 4,000 Hz) was 13.60 ± 7.70 dB. Only 1 patient showed a loss of the PTA by >20 dB. For these 5 patients, the cone beam CT findings showed that all the electrode arrays were in the tympanic ramp and had a grade of 0. The results were compared with those obtained from a cohort of 17 patients who underwent manual implantation of a MED-El Flex 24-electrode array. Conclusion: To minimize disturbance to the cochlea while atraumatic electrode arrays are inserted, electrodes can be inserted at a constant, slow speed in the inner ear with the assistance of the RobOtol® robot in a normal clinical surgical setting.

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Manufacturable 32-Channel Cochlear Electrode Array and Preliminary Assessment of Its Feasibility for Clinical Use

Micromachines ◽

10.3390/mi12070778 ◽

2021 ◽

Vol 12 (7) ◽

pp. 778

Author(s):

Soowon Shin ◽

Yoonhee Ha ◽

Gwangjin Choi ◽

Junewoo Hyun ◽

Sangwoo Kim ◽

...

Keyword(s):

Electrochemical Impedance ◽

Signal Transmission ◽

Round Window ◽

Electrode Array ◽

Lead Wire ◽

Layer By Layer ◽

Electrode Arrays ◽

Insertion Force ◽

Vertical Stiffness ◽

Channel Electrode

(1) Background: In this study, we introduce a manufacturable 32-channel cochlear electrode array. In contrast to conventional cochlear electrode arrays manufactured by manual processes that consist of electrode-wire welding, the placement of each electrode, and silicone molding over wired structures, the proposed cochlear electrode array is manufactured by semi-automated laser micro-structuring and a mass-produced layer-by-layer silicone deposition scheme similar to the semiconductor fabrication process. (2) Methods: The proposed 32-channel electrode array has 32 electrode contacts with a length of 24 mm and 0.75 mm spacing between contacts. The width of the electrode array is 0.45 mm at its apex and 0.8 mm at its base, and it has a three-layered arrangement consisting of a 32-channel electrode layer and two 16-lead wire layers. To assess its feasibility, we conducted an electrochemical evaluation, stiffness measurements, and insertion force measurements. (3) Results: The electrochemical impedance and charge storage capacity are 3.11 ± 0.89 kOhm at 1 kHz and 5.09 mC/cm2, respectively. The V/H ratio, which indicates how large the vertical stiffness is compared to the horizontal stiffness, is 1.26. The insertion force is 17.4 mN at 8 mm from the round window, and the maximum extraction force is 61.4 mN. (4) Conclusions: The results of the preliminary feasibility assessment of the proposed 32-channel cochlear electrode array are presented. After further assessments are performed, a 32-channel cochlear implant system consisting of the proposed 32-channel electrode array, 32-channel neural stimulation and recording IC, titanium-based hermetic package, and sound processor with wireless power and signal transmission coil will be completed.

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Evaluation of Intracochlear Trauma Caused by Insertion of Cochlear Implant Electrode Arrays through Different Quadrants of the Round Window

BioMed Research International ◽

10.1155/2015/236364 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Graziela de Souza Queiroz Martins ◽

Rubens Vuono Brito Neto ◽

Robinson Koji Tsuji ◽

Eloisa Maria Mello Santiago Gebrim ◽

Ricardo Ferreira Bento

Keyword(s):

Cochlear Implant ◽

Round Window ◽

Electrode Array ◽

Hearing Preservation ◽

Round Window Membrane ◽

Residual Hearing ◽

Electrode Arrays ◽

Minimal Trauma ◽

Electrode Insertion ◽

Temporal Bones

Hypothesis. This study aimed to evaluate whether there is a difference in the degree of intracochlear trauma when the cochlear implant electrode arrays is inserted through different quadrants of the round window membrane.Background. The benefits of residual hearing preservation in cochlear implant recipients have promoted the development of atraumatic surgeries. Minimal trauma during electrode insertion is crucial for residual hearing preservation.Methods. In total, 25 fresh human temporal bones were subjected to mastoidectomy and posterior tympanotomy. The cochlear implant electrode array was inserted through the anterosuperior quadrant of the round window membrane in 50% of the bones and through the anteroinferior quadrant in the remaining 50%. The temporal bones were dehydrated, embedded in epoxy, serially polished, stained, viewed through a stereomicroscope, and photographed with the electrode arraysin situ. The resulting images were analyzed for signs of intracochlear trauma.Results. Histological examinations revealed varying degrees of damage to the intracochlear structures, although the incidence and severity of intracochlear trauma were not influenced by the quadrant of insertion.Conclusions. The incidence and severity of intracochlear trauma were similar in all samples, irrespective of electrode array insertion through the anterosuperior or anteroinferior quadrant of the round window membrane.

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