Intraoperative Correction of Cochlear Implant Electrode Translocation.

INTRODUCTION: Translocation of precurved cochlear implant (CI) electrodes reduces hearing outcomes, but it is not known whether it is possible to correct scalar translocation such that all electrodes reside fully in the scala tympani (ST). METHODS: Six cadaveric temporal bones were scanned with CT and segmented to delineate intracochlear anatomy. Mastoidectomy with facial recess was performed. Precurved CI electrodes (CI532; Cochlear Limited) were implanted until scalar translocation was confirmed with postoperative CT. Then, electrodes were removed and replaced. CT scan was repeated to assess for translocation correction. Scalar position of electrode contacts, angular insertion depth (AID) of the electrode array, and M- (average distance between each electrode contact and the modiolus) were measured. An in vivo case is reported in which intraoperative translocation detection led to removal and replacement of the electrode. RESULTS: Five of 6 cadaveric translocations (83%) were corrected with 1 attempt, resulting in full ST insertions. AID averaged 285 ± 77° for translocated electrodes compared to 344 ± 28° for nontranslocated electrodes (p = 0.109). M- averaged 0.75 ± 0.18 mm for translocated electrodes and 0.45 ± 0.11 mm for nontranslocated electrodes (p = 0.016). Reduction in M- with translocation correction averaged 38%. In the in vivo case, translocation was successfully corrected in a single attempt. CONCLUSION: Scalar translocation of precurved CI electrodes can be corrected by removal and reinsertion. This significantly improves the perimodiolar positioning of these electrodes. There was a high rate of success (83%) in this cadaveric model as well as a successful in vivo attempt.

Effect of Proximity to the Modiolus for the Cochlear CI532 Slim Modiolar Electrode Array on Evoked Compound Action Potentials and Programming Levels.

BACKGROUND: The first surgeries with CI532 showed an effect of the proximity of the electrode to the modiolus on the Evoked Compound Action Potentials (ECAPs). OBJECTIVES: Objectives of the study were to investigate the effect of the "pullback" procedure on intraoperative ECAP responses in three different electrode array positions and additionally to compare behavioral thresholds with the thresholds obtained in a group of patients using the standard insertion. The hypothesis of this study is that pullback will cause lower ECAPs and behavioral thresholds. PATIENTS: The study included 40 patients, 20 in the pullback insertion group and 20 in the standard insertion group (without pullback). METHOD: During insertion of the CI532 electrode array, ECAP was performed in three different positions for the pullback group: at initial insertion, at over-insertion, and after pullback. Insertion was monitored by fluoroscopy. In the standard group, ECAP was performed at the initial position, which is also the final position. ECAP thresholds (T-ECAPs) were compared within subjects at the initial and the final position in the pullback group and between groups in the final positions of the pullback and standard groups. Programming levels (C- and T-levels) were compared between the two groups 1 year after switch-on. RESULTS: Intraoperative measurements pullback shows lower average T-ECAPs after pullback compared to thresholds in initial position. Comparison of intraoperative T-ECAPs at the final positions showed no statistically significant difference between the pullback group and the standard insertion group. Furthermore, 1 year after switch-on there was no statistically significant difference in C- and T-levels between the two groups. CONCLUSION: The pullback maneuver of the CI532 electrode array after an over-insertion gave significantly lower T-ECAPs compared to the thresholds at the initial position. However, the between-groups analysis of pullback and standard insertion showed neither significantly different T-ECAPs nor different programming levels. Because T-ECAPs and programming levels vary considerably between subjects, large groups are required to detect differences between groups. Additionally, the effect pullback technique to preserving the residual hearing is not known yet.

Longitudinal outcomes of cochlear implantation and bimodal hearing in a large group of adults: A multicenter clinical study.

OBJECTIVE: To evaluate speech understanding outcomes in a large adult cohort who demonstrated poor hearing performance with well fit hearing aids in the unilateral and bilateral or bimodal listening conditions at preimplant, 3-, 6- and 12-months. SUBJECTS: Post-linguistically deafened adults (N = 100) with bilateral moderate-to-profound sensorineural hearing loss and limited functional benefit from well fit bilateral hearing aids. METHOD: A multicenter, prospective, repeated-measures, within-subject controlled study was conducted. All subjects were implanted with a Slim Modiolar cochlear implant and were required to use bimodal stimulation (cochlear implant and hearing aid in contralateral ear) for 6-months postimplant and optionally to 12-months. Evaluations included: speech recognition for monosyllabic consonant-nucleus-consonant (CNC) words in quiet; AzBio sentences in coincident noise (at +5 and +10 dB signal-to-noise ratio (SNR)), in implant ear and bimodal conditions. All speech tests were performed at preimplant and 6-months postimplant for primary endpoint outcomes, and a subset of speech tests at 3- and 12-months. RESULTS: In the implant ear only, at 3-, 6- and 12-months postimplant, 84%, 93% and 97% of subjects respectively, demonstrated significantly improved monosyllabic word scores in quiet compared to preimplant hearing aid scores (p < 0.05). At 12-months, a mean gain of 51% points, for monosyllabic words and 32% points for sentences in noise was observed (p < 0.001). In the bimodal condition, at 6-months postimplant, 87% of subjects demonstrated significantly improved monosyllabic word scores in quiet compared to preimplant bilateral hearing aid scores (p < 0.05). At 6-months, a mean gain of 40% points, for monosyllabic words was observed (p < 0.001). Speech scores for sentences in noise significantly improved for the bimodal condition at 6- and 12-months (p < 0.001). In addition to speech scores for the implanted ear, bimodal condition scores demonstrated further increments, especially for sentences in noise at 6- and 12-months (p < 0.001). CONCLUSION: Results support that bimodal hearing is superior to bilateral hearing aids in this cohort of bilateral moderate-to-profound adult hearing aid users. Our study cohort demonstrated significant improvements for speech scores for the cochlear implant (CI) ear only and bimodal conditions compared to the baseline preimplant unilateral and bilateral hearing aid conditions respectively. The greatest gain in performance was in the first three months of device use with incremental improvement through 12 months. These findings indicate that when hearing aids fit to National Acoustics Laboratory (NAL-1) targets do not provide the necessary audibility needed for speech recognition, referral for CI-candidacy evaluation is strongly recommended. TRIAL REGISTRATION: Clintrial.govNCT03007472. Registered 01/02/2017, https://clinicaltrials.gov/ct2/show/NCT03007472?term=clinical+evaluation+of+the+nucleus+CI532&draw=2&rank=2.

The influence of Slim Modiolar electrode on residual hearing in pediatric patients.

PURPOSE: Hearing preservation cochlear implantation is an established procedure in patients with low-frequency residual hearing, especially in pediatric cochlear implantation. More delicate, thin electrode arrays can minimize damage in the inner ear and enhance the possibility for residual hearing preservation. The Cochlear® CI532 electrode has been reported as an electrode with the potential for residual hearing preservation. No similar studies pertaining to hearing preservation in pediatric patients have appeared to date. The aim of this study was to investigate whether the Cochlear® CI532 Slim Modiolar electrode allows the preservation of low-frequency residual hearing in children undergoing cochlear implantation. METHODS: In this multicenter, nonrandomized, prospective clinical cohort study, medical data of 14 pediatric patients implanted with the CI532 were collected. All patients had residual low-frequency hearing (preoperative audiogram or ABR with at least one threshold better than 90 dB HL at 125, 250, 500, or 1000 Hz). Postoperative thresholds were obtained 1, 3, 6, and 12 months after cochlear implantation. RESULTS: Based on the HEARRING classification, 78.6% of children (11/14) had complete hearing preservation at the last follow-up visit (12 months after CI, or if not available, 6 months). A total of 21.4% (3/14) had partial hearing preservation. At the last follow-up visit, neither minimal hearing preservation nor loss of hearing was observed. Functional low-frequency hearing was preserved in 13 out of 14 patients (93%). CONCLUSIONS: The residual hearing preservation results in children were superior to the results previously reported in adults.

[Possibilities for residual hearing preservation with Nucleus CI532 Slim Modiolar electrode array. Case report]. / A maradványhallás megorzésének lehetoségei cochlearis implantáció során Nucleus CI532 Slim Modiolar elektródasorral.

During the rehabilitation of hearing-impaired patients, the preservation of residual acoustic hearing following cochlear implantation by minimizing the implantation trauma allows for improved hearing performance. To achieve this, minimally invasive, soft surgery methods and thinner, atraumatic electrodes were required. In our present study, we reported a case where Cochlear® Nucleus CI532 Slim Modiolar electrode was implanted in a patient with residual hearing. Our aim was to study the possible preservation of postoperative acoustic residual hearing by audiological monitoring. Since childhood, due to her congenital hearing loss, she has been wearing a conventional, airborne hearing correction device on both ears. Six months before cochlear implantation, we measured the progression on both sides of the hearing loss, so we decided to perform cochlear implantation. The patient had residual hearing on both ears prior to surgery thus the Cochlear® Nucleus CI532 Slim Modiolar Implant was used. The minimally invasive surgery was performed on the patient's right ear through the round window approach. Compared to the preoperative hearing threshold (average 85 dBHL) in the 4th postoperative week, an initial hearing threshold progression of 20-25 dBHL was observed between 0.25 and 1.0 kHz, while of 5-10 dBHL between 2.0-4.0 kHz. Hearing threshold measured in the 6th month showed a slight progression in the range above 1 kHz, but improved by the 12th month, to the results achieved at the 4th week. The effects of cochlear implantation on residual hearing have been studied in numerous studies, in which several key surgical and technical factors have been identified. Nucleus CI532 is a Slim Modiolar electrode profile that is close to the modiolus, so it is expected to have a lower endocochlear hydrodynamic load since it lies in the covering of the osseus spiral lamina, thus less influencing the dynamics of the basilar membrane. However, the perimodiolar location of the electrode array allows the adjacent nerve elements of the spiral ganglion to be stimulated with a lower electrical intensity and a reduced surface that may be neuroprotective. Preservation of acoustic residual hearing following cochlear implantation improves the patient's speech perception and the sound localization skills, particularly in difficult circumstances. Long-term residual hearing preservation may also be of great importance in the subsequent feasibility for regenerative procedures and drug treatments. Orv Hetil. 2018; 159(41): 1680-1688.

Cochlear implantation with the nucleus slim modiolar electrode (CI532): a preliminary experience.

To combine the benefits of perimodiolar stimulation with minimal insertion trauma, a thin, pre-curved electrode (CI532) was recently developed by Cochlear Ltd. (Sidney). This array is held straight prior to insertion by an external polymer reloadable sheath that is removed after full electrode insertion. Sixty-seven patients suffering from severe-to-profound sensorineural hearing loss (mean age 42.2 years; mean duration of the hearing loss 19.6 years; mean PTA thresholds at 250-2000 Hz 92.4 dB HL) were implanted with the CI532. Mean duration of surgery was 58.7 min. In 61 patients, a round window (RW) approach was used. In the remaining six cases, a cochleostomy was done because of RW ossification. Impedances and NRT for each electrode are reported. NRT ratio average value was 0.86 ± 0.12 predicting correct scala tympani electrode placement. Post-operative PTA threshold in the implanted ear was 102.9 dB HL. Finally, speech recognition level in quiet at 65 dB HL was 44.6%, after a short follow-up (mean 5.2 months). Our preliminary experience with the new CI532 shows good surgical, electrophysiological, and audiological outcomes. In particular, our results are promising regarding the possibility to achieve minimal insertion trauma and good residual hearing preservation with the use of a deep inserted close modiolar electrode.

Hearing preservation with a slim modiolar cochlear implant in a pediatric cohort.

OBJECTIVES: Recent cochlear implant (CI) electrodes are designed to be atraumatic to inner ear structures. Studies in adults have demonstrated improved hearing preservation rates with the CI532/632 electrode, but none have examined this in children. Our objective is to describe the hearing preservation rate with CI532/632 in pediatric patients and determine factors that influence hearing preservation. METHODS: We conducted a retrospective cohort study of children undergoing CI over a three-year period. Inclusion criteria were: CI with the 532/632 electrode, presence of pre-operative low frequency hearing defined by pure tone average (PTA) of ≤80 dB at 250 Hz or at the average of 250 and 500 Hz, and post-operative unaided audiometry. Other data collected included demographics, otologic history, imaging, and surgical details. RESULTS: A total of 13 patients and 15 ears were included. Hearing was preserved in 10/15 (66%) ears at an average follow-up of 6 months, similar to that reported in the adult literature. Patients with preserved hearing post-operatively were more likely to have a positive family history of hearing loss. There was a trend towards patients with anatomic inner ear abnormalities being more likely to lose hearing after CI, but this was not statistically significant. Pre-operative thresholds were not predictive of hearing preservation. Patients with preserved hearing had a significantly smaller shift in thresholds after cochlear implantation. Therefore, hearing preserved and non-preserved groups differed more by the magnitude of change in threshold, rather than their preoperative threshold. Other factors such as age, sex, surgeon, and surgery duration were not associated with hearing preservation. CONCLUSION: This study describes low frequency hearing preservation after pediatric CI532/632 implantation. The hearing preservation rate in our cohort was consistent with that reported in the adult literature. Our data suggest that preoperative thresholds do not solely determine which patients will go on to experience hearing preservation. We believe this will aid surgeons with patient-specific device selection and counseling potential pediatric CI recipients with preserved hearing.

Initial surgical and clinical experience with the Nucleus CI532 slim modiolar electrode in the UK.

OBJECTIVE: The goal of this work is to describe the first experience in the UK with the slim pre-curved perimodiolar electrode Nucleus CI532 in a continuous series of patients in terms of surgical and clinical reliability and early performance outcomes. METHOD: In this retrospective review we describe the complication rate (including electrode array tip fold-over), NRT thresholds, hearing preservation, power efficiency and CI performance outcomes in a continuous series of 40 cochlear implants CI532 performed between October 2016 and November 2017 in 17 adults and 13 children with severe to profound hearing loss. RESULTS: Preliminary data from these groups reveals some low-frequency hearing preservation in the CI532 group although none of the patients were conventional hearing preservation candidates. NRT thresholds, power efficiency, and BKB sentences in quiet were measured at 3 and 6 months post activation. There were no significant differences in these results. The average BKB score in quiet increases from 22% pre-operatively to 58% at 3 months and 70% at 6 months. In addition, although hearing preservation was not an objective, low-frequency thresholds were preserved in 20% of cases at 3 and 6 months post-operatively. Complications were observed in 5 cases, one case with non-device related aerocoele and four related to the device array: two cases of tip roll over, one case of the electrode array being placed extra-cochlea, and one case with the electrode buckling into the middle ear. The last 2 cases were dealt with per-operatively. DISCUSSION: Our preliminary results with the CI532 implant indicate that it may be reliably placed with standard surgical techniques but care is needed during the deployment of the electrode. Further initial data suggest that switch on and early electrophysiological measures are comparable to the existing CI 512 device. However whilst preliminary, our data suggest that it may be possible to use this electrode for hearing preservation. However, further studies are required to determine its definitive advantage over other electrode designs. CONCLUSION: CI532 is a reliable device offering good initial results and could be an option for hearing preservation although further studies are required.