An In-Vitro Insertion-Force Study of Magnetically Guided Lateral-Wall Cochlear-Implant Electrode Arrays

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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Frictional Behavior of Cochlear Electrode Array Is Dictated by Insertion Speed and Impacts Insertion Force

Applied Sciences ◽

10.3390/app11115162 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5162

Author(s):

Dana Dohr ◽

Nicklas Fiedler ◽

Wolfram Schmidt ◽

Niels Grabow ◽

Robert Mlynski ◽

...

Keyword(s):

Friction Coefficient ◽

Cochlear Implant ◽

Electrode Array ◽

Mechanical Trauma ◽

Electrode Arrays ◽

Friction Behavior ◽

Insertion Force ◽

Friction Coefficients ◽

Electrode Insertion ◽

The Impact

Background: During cochlear implantation, the electrode array has significant friction with the sensitive endocochlear lining and causes mutual mechanical trauma while the array is being inserted. Both, the impact of insertion speed on electrode friction and the relationship of electrode insertion force and friction have not been adequately investigated to date. Methods: In this study, friction coefficients between a CI electrode array (31.5 mm) and a tissue simulating the endocochlear lining have been acquired, depending on different insertion speeds (0.1, 0.5, 1.0, 1.5, and 2.0 mm/s). Additionally, the electrode insertion forces during the placing into a scala tympani model were recorded and correlated with the friction coefficient. Results: It was shown that the friction coefficient reached the lowest value at an insertion speed of 0.1 mm/s (0.24 ± 0.13), a maximum occurred at 1.5 mm/s (0.59 ± 0.12), and dropped again at 2 mm/s (0.45 ± 0.11). Similar patterns were observed for the insertion forces. Consequently, a high correlation coefficient (0.9) was obtained between the insertion forces and friction coefficients. Conclusion: The present study reveals a non-linear increase in electrode array friction, when insertion speed raises and reports a high correlation between friction coefficient and electrode insertion force. This dependence is a relevant future parameter to evaluate and reduce cochlear implant insertion trauma. Significance statement: Here, we demonstrated a dependence between cochlear electrode insertion speed and its friction behavior and a high correlation to insertion force. Our study provides valuable information for the evaluation and prevention of cochlear implant insertion trauma and supports the optimization of cochlear electrode arrays regarding friction characteristics.

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Force measurement of insertion of cochlear implant electrode arrays in vitro: comparison of surgeon to automated insertion tool

Acta Oto-Laryngologica ◽

10.3109/00016480902998281 ◽

2010 ◽

Vol 130 (1) ◽

pp. 31-36 ◽

Cited By ~ 39

Author(s):

Omid Majdani ◽

Daniel Schurzig ◽

Andreas Hussong ◽

Thomas Rau ◽

Justin Wittkopf ◽

...

Keyword(s):

Cochlear Implant ◽

Force Measurement ◽

Electrode Arrays ◽

Insertion Tool ◽

In Vitro Comparison

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Force measurement of insertion of cochlear implant electrode arrays in vitro: comparison of surgeon to automated insertion tool

Acta Oto-Laryngologica ◽

10.1080/00016480902998281 ◽

2009 ◽

pp. 1-6 ◽

Cited By ~ 9

Author(s):

Omid Majdani ◽

Daniel Schurzig ◽

Andreas Hussong ◽

Thomas Rau ◽

Justin Wittkopf ◽

...

Keyword(s):

Cochlear Implant ◽

Force Measurement ◽

Electrode Arrays ◽

Insertion Tool ◽

In Vitro Comparison

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Speech Recognition Outcomes in Adults With Slim Straight and Slim Modiolar Cochlear Implant Electrode Arrays

Otolaryngology ◽

10.1177/01945998211036339 ◽

2021 ◽

pp. 019459982110363

Author(s):

Margaret E. MacPhail ◽

Nathan T. Connell ◽

Douglas J. Totten ◽

Mitchell T. Gray ◽

David Pisoni ◽

...

Keyword(s):

Speech Recognition ◽

Cochlear Implant ◽

Pure Tone ◽

Lateral Wall ◽

Electrode Arrays ◽

Academic Hospital ◽

Pure Tone Average ◽

Data Log ◽

Percentage Correct

Objective To compare differences in audiologic outcomes between slim modiolar electrode (SME) CI532 and slim lateral wall electrode (SLW) CI522 cochlear implant recipients. Study Design Retrospective cohort study. Setting Tertiary academic hospital. Methods Comparison of postoperative AzBio sentence scores in quiet (percentage correct) in adult cochlear implant recipients with SME or SLW matched for preoperative AzBio sentence scores in quiet and aided and unaided pure tone average. Results Patients with SLW (n = 52) and patients with SME (n = 37) had a similar mean (SD) age (62.0 [18.2] vs 62.6 [14.6] years, respectively), mean preoperative aided pure tone average (55.9 [20.4] vs 58.1 [16.4] dB; P = .59), and mean AzBio score (percentage correct, 11.1% [13.3%] vs 8.0% [11.5%]; P = .25). At last follow-up (SLW vs SME, 9.0 [2.9] vs 9.9 [2.6] months), postoperative mean AzBio scores in quiet were not significantly different (percentage correct, 70.8% [21.3%] vs 65.6% [24.5%]; P = .29), and data log usage was similar (12.9 [4.0] vs 11.3 [4.1] hours; P = .07). In patients with preoperative AzBio <10% correct, the 6-month mean AzBio scores were significantly better with SLW than SME (percentage correct, 70.6% [22.9%] vs 53.9% [30.3%]; P = .02). The intraoperative tip rollover rate was 8% for SME and 0% for SLW. Conclusions Cochlear implantation with SLW and SME provides comparable improvement in audiologic functioning. SME does not exhibit superior speech recognition outcomes when compared with SLW.

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Temporal Pitch Perception in Cochlear-Implant Users: Channel Independence in Apical Cochlear Regions

Trends in Hearing ◽

10.1177/23312165211020645 ◽

2021 ◽

Vol 25 ◽

pp. 233121652110206

Author(s):

Andreas Griessner ◽

Reinhold Schatzer ◽

Viktor Steixner ◽

Gunesh P. Rajan ◽

Clemens Zierhofer ◽

...

Keyword(s):

Cochlear Implant ◽

Lateral Wall ◽

Apical Region ◽

Electrode Arrays ◽

Short Delay ◽

Pulse Trains ◽

Temporal Cues ◽

Single Sided Deafness ◽

Temporal Rate ◽

Bilateral Deafness

Two-electrode stimuli presented on adjacent mid-array contacts in cochlear-implant users elicit pitch percepts that are not consistent with a summation of the two temporal patterns. This indicates that low-rate temporal rate codes can be applied with considerable independence on adjacent mid-array electrodes. At issue in this study was whether a similar independence of temporal pitch cues can also be observed for more apical sites of stimulation, where temporal cues have been shown to be more reliable than place cues, in contrast to middle and basal sites. In cochlear-implant recipients with single-sided deafness implanted with long lateral-wall electrode arrays, pitch percepts were assessed by matching the pitch of dual-electrode stimuli with pure tones presented to the contralateral normal-hearing ear. The results were supported with an additional pitch-ranking experiment, in a different subject population with bilateral deafness. Unmodulated pulse trains with 100, 200, and 400 pulses per second were presented on three pairs of adjacent electrodes. Pulses were separated by the minimal interchannel delay (1.7 µs) in a short-delay configuration and by half the pulse period in a long-delay configuration. The hypothesis was that subjects would perceive a pitch corresponding to the doubled temporal pattern for the long-delay stimuli due to the summation of excitation patterns from adjacent apical electrodes, if those electrodes were to activate largely overlapping neural populations. However, we found that the mean matched acoustic pitch of the long-delay pulses was not significantly different from that of the short-delay pulses. These findings suggest that also in the apical region in long-array cochlear-implant recipients, temporal cues can be transmitted largely independently on adjacent electrodes.

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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 Migration in Patients with Perimodiolar Cochlear Implant Electrodes

Audiology and Neurotology ◽

10.1159/000435873 ◽

2015 ◽

Vol 20 (6) ◽

pp. 349-353 ◽

Cited By ~ 9

Author(s):

Philipp Mittmann ◽

Grit Rademacher ◽

Sven Mutze ◽

Arneborg Ernst ◽

Ingo Todt

Keyword(s):

Cochlear Implant ◽

Cochlear Implantation ◽

Electrode Array ◽

Lateral Wall ◽

Electrode Arrays ◽

Insertion Depth ◽

Lower Extent ◽

Uncommon Complication

Migration of a cochlear implant electrode is a hitherto uncommon complication. So far, array migration has only been observed in lateral wall electrodes. Between 1999 and 2014, a total of 27 patients received bilateral perimodiolar electrode arrays at our institution. The insertion depth angle was estimated on the initial postoperative scans and compared with the insertion depth angle of the postoperative scans performed after contralateral cochlear implantation. Seven (25.93%) patients were found to have an electrode array migration of more than 15°. Electrode migration in perimodiolar electrodes seems to be less frequent and to occur to a lower extent than in lateral wall electrodes. Electrode migration was clinically asymptomatic in all cases.

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