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

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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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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Intracochlear Fluid Pressure Changes Related to the Insertional Speed of a CI Electrode

BioMed Research International ◽

10.1155/2014/507241 ◽

2014 ◽

Vol 2014 ◽

pp. 1-4 ◽

Cited By ~ 20

Author(s):

I. Todt ◽

P. Mittmann ◽

A. Ernst

Keyword(s):

Cochlear Implant ◽

Pressure Sensor ◽

Fluid Pressure ◽

Linear Actuator ◽

Residual Hearing ◽

Cochlear Model ◽

First Results ◽

Electrode Insertion ◽

Pressure Changes

Introduction. To preserve residual hearing the atraumaticity of the cochlea electrode insertion has become a focus of cochlear implant research. In addition to other factors, the speed of insertion is thought to be a contributing factor in the concept of atraumatic implantation. The aim of our study was to observe intracochlear fluid pressure changes due to different insertional speeds of an implant electrode in a cochlear model.Materials and Methods. The experiments were performed using an artificial cochlear model. A linear actuator was mounted on an Advanced Bionics IJ insertional tool. The intracochlear fluid pressure was recorded through a pressure sensor which was placed in the helicotrema area. Defined insertions were randomly performed with speeds of 0.1 mm/sec, 0.25 mm/sec, 0.5 mm/sec, 1 mm/sec, and 2 mm/sec.Results. A direct correlation between speed and pressure was observed. Mean maximum values of intracochlear fluid pressure varied between 0.41 mm Hg and 1.27 mm Hg.Conclusion. We provide the first results of fluid pressure changes due to insertional speeds of CI electrodes in a cochlear model. A relationship between the insertional speed and intracochlear fluid pressure was observed. Further experiments are needed to apply these results to the in vivo situation.

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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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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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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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The Effects of Gusher-Related Intracochlear Pressure Changes on Hearing Preservation in Cochlear Implantation: A Comparative Series

Audiology and Neurotology ◽

10.1159/000489599 ◽

2018 ◽

Vol 23 (3) ◽

pp. 181-186 ◽

Cited By ~ 1

Author(s):

William Crohan ◽

Jay Krishnaswamy ◽

Gunesh Rajan

Keyword(s):

Cochlear Implantation ◽

Large Change ◽

Lateral Wall ◽

Hearing Preservation ◽

Residual Hearing ◽

Electrode Arrays ◽

Significant Drop ◽

Speech Performance ◽

Intracochlear Pressure ◽

Pressure Changes

Aim: To investigate and compare residual hearing preservation between patients based on the presence of intraoperative gusher. Methodology: We retrospectively compared 2 cohorts of cochlear implant recipients significantly distinguished by whether or not they experienced gusher intraoperatively. Patients underwent cochlear implantation using 24-mm lateral wall electrode arrays as well pharmacologic steroid protection. All patients were assessed by a hearing implant MDT. Hearing preservation rates and speech perception outcomes were assessed at 1, 6, 12, 24, 36, 48, and 60 months. Results: The patients with no gusher demonstrated complete hearing preservation. The patients with gusher demonstrated significant postoperative reduction of hearing thresholds, which declined at a significantly higher pace during follow-up. All patients demonstrated significantly better speech performance after cochlear implantation. Conclusion: The present study suggests that intraoperative gusher is associated with a significant drop in residual hearing, both immediately and over time, which may be related to the large change in intracochlear pressure intraoperatively.

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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

Audiology and Neurotology ◽

10.1159/000499154 ◽

2019 ◽

Vol 24 (1) ◽

pp. 38-48 ◽

Cited By ~ 3

Author(s):

Jeroen P.M. Peters ◽

Edwin Bennink ◽

Gijsbert A. van Zanten

Keyword(s):

Cochlear Implant ◽

Spiral Ganglion ◽

Electrode Array ◽

Lateral Wall ◽

Electrode Arrays ◽

High Resolution Computed Tomography ◽

Significant Difference ◽

Electrode Contact ◽

The Difference ◽

Single Sided Deafness

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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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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