Comparison of Place-versus-Pitch Mismatch between a Perimodiolar and Lateral Wall Cochlear Implant Electrode Array in Patients with Single-Sided Deafness and a Cochlear Implant

Background: In electric-acoustic pitch matching experiments in patients with single-sided deafness and a cochlear implant, the observed “mismatch” between perceived pitch and predicted pitch, based on the amended Greenwood frequency map, ranges from –1 to –2 octaves. It is unknown if and how this mismatch differs for perimodiolar versus lateral wall electrode arrays. Objectives: We aimed to investigate if the type of electrode array design is of influence on the electric-acoustic pitch match. Method: Fourteen patients (n = 8 with CI422 + lateral wall electrode array, n = 6 with CI512 + perimodiolar electrode array; Cochlear Ltd.) compared the pitch of acoustic stimuli to the pitch of electric stimuli at two test sessions (average interval 4.3 months). We plotted these “pitch matches” per electrode contact against insertion angle, calculated from high-resolution computed tomography scans. The difference between these pitch matches and two references (the spiral ganglion map and the default frequency allocation by Cochlear Ltd.) was defined as “mismatch.” Results: We found average mismatches of –2.2 octaves for the CI422 group and –1.3 octaves for the CI512 group. For any given electrode contact, the mismatch was smaller for the CI512 electrode array than for the CI422 electrode array. For all electrode contacts together, there was a significant difference between the mismatches of the two groups (p < 0.05). Results remained stable over time, with no significant difference between the two test sessions considering all electrode contacts. Neither group showed a significant correlation between the mismatch and phoneme recognition scores. Conclusion: The pitch mismatch was smaller for the perimodiolar electrode array than for the lateral wall electrode array.

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Searching for the Sound of a Cochlear Implant: Evaluation of Different Vocoder Parameters by Cochlear Implant Users With Single-Sided Deafness

Trends in Hearing ◽

10.1177/2331216519866029 ◽

2019 ◽

Vol 23 ◽

pp. 233121651986602 ◽

Cited By ~ 3

Author(s):

Chadlia Karoui ◽

Chris James ◽

Pascal Barone ◽

David Bakhos ◽

Mathieu Marx ◽

...

Keyword(s):

Cochlear Implant ◽

Spiral Ganglion ◽

Electrode Arrays ◽

Harmonic Complex ◽

Frequency Mismatch ◽

Analysis And Synthesis ◽

Electrode Contact ◽

Forced Choice Task ◽

Single Sided Deafness ◽

Sound Processor

Cochlear implantation in subjects with single-sided deafness (SSD) offers a unique opportunity to directly compare the percepts evoked by a cochlear implant (CI) with those evoked acoustically. Here, nine SSD-CI users performed a forced-choice task evaluating the similarity of speech processed by their CI with speech processed by several vocoders presented to their healthy ear. In each trial, subjects heard two intervals: their CI followed by a certain vocoder in Interval 1 and their CI followed by a different vocoder in Interval 2. The vocoders differed either (i) in carrier type—(sinusoidal [SINE], bandfiltered noise [NOISE], and pulse-spreading harmonic complex) or (ii) in frequency mismatch between the analysis and synthesis frequency ranges—(no mismatch, and two frequency-mismatched conditions of 2 and 4 equivalent rectangular bandwidths [ERBs]). Subjects had to state in which of the two intervals the CI and vocoder sounds were more similar. Despite a large intersubject variability, the PSHC vocoder was judged significantly more similar to the CI than SINE or NOISE vocoders. Furthermore, the No-mismatch and 2-ERB mismatch vocoders were judged significantly more similar to the CI than the 4-ERB mismatch vocoder. The mismatch data were also interpreted by comparing spiral ganglion characteristic frequencies with electrode contact positions determined from postoperative computed tomography scans. Only one subject demonstrated a pattern of preference consistent with adaptation to the CI sound processor frequency-to-electrode allocation table and two subjects showed possible partial adaptation. Those subjects with adaptation patterns presented overall small and consistent frequency mismatches across their electrode arrays.

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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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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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Preservation of residual hearing following cochlear implantation: comparison between three surgical techniques

The Journal of Laryngology & Otology ◽

10.1017/s0022215107000254 ◽

2007 ◽

Vol 122 (3) ◽

pp. 246-252 ◽

Cited By ~ 36

Author(s):

S Berrettini ◽

F Forli ◽

S Passetti

Keyword(s):

Cochlear Implant ◽

Cochlear Implantation ◽

Surgical Techniques ◽

Electrode Array ◽

Lateral Wall ◽

Hearing Preservation ◽

Acoustic Stimulation ◽

Residual Hearing ◽

Electrode Arrays ◽

Electrode Insertion

AbstractThe preservation of residual hearing is becoming a high priority in cochlear implant surgery. It allows better speech understanding and ensures long-lasting and stable performance; it also allows the possibility, in selected cases, of combining electro-acoustic stimulation in the same ear.We present the results of a retrospective study of the conservation of residual hearing in three different groups of patients who had undergone cochlear implantation using three different cochlear implant electrode arrays, combined with three different surgical techniques for the cochleostomy. The study aimed to evaluate which approach allowed greater preservation of residual hearing.The best residual hearing preservation results (i.e. preservation in 81.8 per cent of patients) were achieved with the Contour Advance electrode array, using the Advance Off-Stylet technique and performing a modified anterior inferior cochleostomy; this combination enabled reduced trauma to the lateral wall of the cochlea during electrode insertion.

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The Importance of Intraoperative Plain Radiographs during Cochlear Implant Surgery in Patients with Normal Anatomy

Applied Sciences ◽

10.3390/app11094144 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4144

Author(s):

Ohad Cohen ◽

Jean-Yves Sichel ◽

Chanan Shaul ◽

Itay Chen ◽

J. Thomas Roland ◽

...

Keyword(s):

Cochlear Implant ◽

Electrode Array ◽

Cost Effective ◽

X Rays ◽

Normal Anatomy ◽

Electrode Arrays ◽

Plain Radiographs ◽

Hearing Function ◽

Tertiary Center ◽

Cochlear Implant Surgery

Although malpositioning of the cochlear implant (CI) electrode array is rare in patients with normal anatomy, when occurring it may result in reduced hearing outcome. In addition to intraoperative electrophysiologic tests, imaging is an important modality to assess correct electrode array placement. The purpose of this report was to assess the incidence and describe cases in which intraoperative plain radiographs detected a malpositioned array. Intraoperative anti-Stenver’s view plain X-rays are conducted routinely in all CI surgeries in our tertiary center before awakening the patient and breaking the sterile field. Data of patients undergoing 399 CI surgeries were retrospectively analyzed. A total of 355 had normal inner ear and temporal bone anatomy. Patients with intra or extracochlear malpositioned electrode arrays demonstrated in the intraoperative X-ray were described. There were four cases of electrode array malposition out of 355 implantations with normal anatomy (1.1%): two tip fold-overs, one extracochlear placement and one partial insertion. All electrodes were reinserted immediately; repeated radiographs were normal and the patients achieved good hearing function. Intraoperative plain anti-Stenver’s view X-rays are valuable to confirm electrode array location, allowing correction before the conclusion of surgery. These radiographs are cheaper, faster, and emit much less radiation than other imaging options, making them a viable cost-effective tool in patients with normal anatomy.

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Intraoperative transimpedance and spread of excitation profile correlations with a lateral-wall cochlear implant electrode array

Hearing Research ◽

10.1016/j.heares.2021.108235 ◽

2021 ◽

Vol 405 ◽

pp. 108235

Author(s):

Samuel Söderqvist ◽

Satu Lamminmäki ◽

Antti Aarnisalo ◽

Timo Hirvonen ◽

Saku T. Sinkkonen ◽

...

Keyword(s):

Cochlear Implant ◽

Electrode Array ◽

Lateral Wall ◽

Excitation Profile ◽

Spread Of Excitation

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Magnetic Steering of Robotically Inserted Lateral-wall Cochlear-implant Electrode Arrays Reduces Forces on the Basilar Membrane In Vitro

Otology & Neurotology ◽

10.1097/mao.0000000000003129 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Cameron M. Hendricks ◽

Matt S. Cavilla ◽

David E. Usevitch ◽

Trevor L. Bruns ◽

Katherine E. Riojas ◽

...

Keyword(s):

Cochlear Implant ◽

Basilar Membrane ◽

Lateral Wall ◽

Electrode Arrays ◽

Magnetic Steering

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High resolution computed tomography and magnetic resonance imaging in the pre-operative assessment of cochlear implant patients

The Journal of Laryngology & Otology ◽

10.1258/002221503322334495 ◽

2003 ◽

Vol 117 (9) ◽

pp. 692-695 ◽

Cited By ~ 26

Author(s):

T. G. Gleeson ◽

P. D. Lacy ◽

M. Bresnihan ◽

R. Gaffney ◽

P. Brennan ◽

...

Keyword(s):

Computed Tomography ◽

Magnetic Resonance ◽

Cochlear Implant ◽

High Resolution Computed Tomography ◽

Time Of Surgery ◽

Surgical Access ◽

Significant Difference ◽

Mri Scans ◽

Operative Assessment ◽

Ct And Mri

Optimal imaging protocols for cochlear implantation have yet to be determined. Pre-operative computed tomography (CT) and magnetic resonance image (MRI) scans are used to assess cochlear anatomy and patency, to delineate surgical access, and to aid in choice of side for implantation. However, opinion still differs as to which modality provides more information in pre-operative assessment, or if, indeed, a combination of the two is superior.The first 88 patients on the Irish National Cochlear Implant Programme (NCIP) were retrospectively studied to determine the accuracy of pre-operative CT and MRI in predicting abnormalities at the time of surgery. Correlation with surgical findings was determined in three separate groups of patients (those who had CT only, those who had MRI only, and those who had both CT and MRI performed).Of the 24 patients that had both CT and MRI performed, both modalities had a 79 per cent correlation with surgical findings. CT and MRI reports concurred in 75 per cent of cases. Specificity and negative predictive value were high (86 per cent and 90 per cent, respectively). CT alone (47 cases) correlated with surgery in 39 cases (83 per cent); MRI alone (17 cases) correlated in 15 cases (88 per cent).The findings of this study suggest that CT and MRI are effective at predicting normal inner ear anatomy, and thus at predicting the patient and the cochlea most suitable for implantation. Both modalities are useful in determining the side of implantation, thus avoiding potential surgical difficulties in cases of unilateral abnormalities. There was no significant difference between the ability of MRI and CT to detect abnormalities at the time of surgery. In this series the combination of CT and MRI has not been shown to be superior to either modality used alone, although anecdotal evidence to the contrary was noted.

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