Lateral Wall Arrays Research Articles

Exploring Trauma Patterns and Contributing Factors With Slim Straight Electrode Array After Cochlear Implantation.

To assess trauma patterns associated with the insertion of lateral wall electrode arrays. The study focused on 3 categories-scala tympani (ST), intermediate, and scala vestibuli (SV)-to identify traumatic patterns and contributing factors. Retrospective study. Data from 106 cochlear implant recipients at a tertiary otologic center. Demographic and surgical data were collected from recipients who underwent cochlear implantation manually and with RobOtol®. Measurements included cochlear dimensions, angular depth of insertion, and position of the first electrode. Three-dimensional reconstructions were used to analyze the electrode array location relative to the basilar membrane, categorized into ST, intermediate, and SV electrodes. Nontraumatic insertion was defined as all electrodes in the ST, while traumatic insertions had 1 or more electrodes in intermediate or SV locations. Out of 106 cases, 44% had nontraumatic and 56% had traumatic insertions. Demographic and surgical characteristics showed no association with traumatic insertions. A deeper position of the first electrode, relative to the round window, was associated with traumatic insertions (P = .03). Three trauma patterns were observed: distal (facing the apical electrodes), proximal (facing the middle electrodes around 180°), and distal/proximal. This study considers the intermediate position which could be associated with basilar membrane lesions. Risk zones for intracochlear trauma with lateral wall arrays were identified distally and proximally. Traumatic insertions were independently linked to deeper array placement. Future studies should explore whether gentler insertion, without insisting on further electrode array insertion depth, could reduce the trauma during cochlear implantation.

Frequency-to-Place Mismatch Impacts Cochlear Implant Quality of Life, But Not Speech Recognition.

To retrospectively compare frequency-place mismatch among adult cochlear implant (CI) recipients with lateral wall (LW) and perimodiolar/Mid Scala (PM/MS) arrays, and to quantify the impact of these factors on early post-activation (3 months) speech recognition abilities and CI-specific quality of life. One hundred and twenty-six adult participants were separated into two groups: (1) 83 participants who underwent CI with a PM/MS array and 43 patients who underwent CI with a LW array. All participants completed the Cochlear Implant Quality of Life Profile (CIQOL-35 Profile) instrument. Angular insertion depth and semitone mismatch, which contribute to frequency-place mismatch, were assessed using post-operative CT scans. Word and speech recognition in quiet were determined using the Consonant-Nucleus-Consonant (CNC) and the AzBio tests, respectively (n = 82 patients). LW arrays were more deeply inserted and exhibited less semitone mismatch compared to PM/MS arrays. No significant relationship was found between semitone mismatch and early post-operative speech perception scores for either PM/MS or LW arrays. However, greater degrees of semitone mismatch were associated with lower CIQOL-35 profile scores for PM/MS arrays. The results of this study indicate that both the degree of frequency-place mismatch, and its impact on CI-specific quality of life, vary by CI array design. 4 Laryngoscope, 134:2898-2905, 2024.

Cochlear Implant Electrode Array Design and Speech Understanding.

Cochlear implant electrode arrays are categorized based on their design as lateral wall (LW) and perimodiolar (PM) electrode arrays. The objective of this study was to investigate the effect of LW versus PM designs on postoperative speech perception across multiple manufacturers and over long follow-up durations. Retrospective cohort study. Single academic medical center. A total of 478 adult cochlear implant recipients, implanted between the years 1992 and 2017. PM versus LW cochlear implants. Postoperative Consonant-Nucleus-Consonant Word (CNC-w) and Hearing in Noise Test (HINT) scores between 6 months and 5 years. Across 478 patients, approximately one-third received LW (n = 176, 36.8%), whereas 302 patients received a PM array (63.2%). The PM group had higher CNC-w scores from 6 months to 2 years (52 [interquartile range, 38-68] versus 48 [31-62], p = 0.036) and from 2 to 5 years (58 [43-72] versus 48 [33-66], p < 0.001). Multivariable analysis of patient-averaged scores indicated that the PM group had greater improvement from preoperative scores at all time points after the initial 6 months for both CNC-w ( β = 4.4 [95% confidence interval, 0.6-8.3], p = 0.023) and HINT testing ( β = 4.5 [95% confidence interval, 0.3-8.7], p = 0.038). This study indicates that PM electrode arrays are associated with small increases in postoperative speech perception scores, relative to LW arrays, when assessed across manufacturers, over long time durations, and using multiple outcome instruments. These findings may help guide surgeon selection and patient counseling of cochlear implant arrays.

Variables Affecting Cochlear Implant Performance After Loss of Residual Hearing.

Determine variables that influence post-activation performance for cochlear implant (CI) recipients who lost low-frequency acoustic hearing. A retrospective review evaluated CNC word recognition for adults with normal to moderately severe low-frequency hearing (preoperative unaided thresholds of ≤70 dB HL at 250 Hz) who were implanted between 2012 and 2021 at a tertiary academic center, lost functional acoustic hearing, and were fit with a CI-alone device. Performance scores were queried from the 1, 3, 6, 12, and 24-month post-activation visits. A linear mixed model evaluated the effects of age at implantation, array length (long vs. mid/short), and preoperative low-frequency hearing (normal to mild, moderate, and moderately severe) on speech recognition with a CI alone. 113 patients met the inclusion criteria. There was a significant main effect of interval (p < 0.001), indicating improved word recognition post-activation despite loss of residual hearing. There were significant main effects of age (p = 0.029) and array length (p = 0.038), with no effect of preoperative low-frequency hearing (p = 0.171). There was a significant 2-way interaction between age and array length (p = 0.018), indicating that older adults with mid/short arrays performed more poorly than younger adults with long lateral wall arrays when functional acoustic hearing was lost. CI recipients with preoperative functional low-frequency hearing experience a significant improvement in speech recognition with a CI alone as compared to preoperative performance-despite the loss of low-frequency hearing. Age and electrode array length may play a role in post-activation performance. These data have implications for the preoperative counseling and device selection for hearing preservation candidates. 4 Laryngoscope, 134:1868-1873, 2024.

Electrode-Modiolus Distance Affects Speech Perception for Lateral Wall Electrodes.

The goal of this study was to use cone-beam computed tomography to locate the electrode-modiolus distance (EMD) and correlate this with speech perception in cochlear implant (CI) recipients of the 31.5-mm lateral wall (LW) electrode arrays. Retrospective review. Forty-five child CI recipients with prelingual profound sensorineural hearing loss of inserted 31.5-mm LW arrays listening with a CI-alone device. Stepwise forward multiple linear regression was performed to control and reduce the variability in implant performance to determine whether EMD affects speech perception. Electrode location (angular insertion depth [AID], EMD), together with the electrode impedance (EI), surgical approach, sex, CI age, and preimplant hearing aid usage were estimated as independent variables. The dependent variables were the Meaningful Use of Speech Scale (MUSS) and parents' evaluation of children's aural/oral performance (PEACH) assessed with the CI alone at 12 months postactivation. EMD and CI age were predictive variables for PEACH/MUSS. A negative correlation was found between AID and EMD (r = -0.56, p < 0.01), whereas EMD had a moderately positive correlation with EI (r = 0.32, p < 0.01). The best "location-related" predictor of postoperative speech perception was EMD with a 31.5-mm array among CI-alone users.

One-Year Hearing Preservation and Speech Outcomes Comparing Slim Modiolar and Lateral Wall Arrays.

Compare postoperative speech outcomes in hearing preservation (HP) cochlear implantation (CI) patients with a low-frequency pure-tone average (LFPTA) ≤ 60 dB using 2 electrode array designs. Retrospective cohort study. Large academic cochlear implant referral center. We reviewed adult HP CI cases using either the slim modiolar electrode (SME) (CI 532/CI 632) or thslim lateral wall electrode (SLWE) (CI 624). One-year speech outcomes and HP status were the primary outcomes. A total of 132 implanted ears were analyzed (mean age 73.1 years, standarddeviation[SD] 12.6), with 72% (N = 95) with CI 532/632 and 28% (N = 37) with CI 624. The mean preoperative LFPTA was 44.8 dB, SD 11.8. One-year functional HP was 27.2% (mean LFPTA shift 46.1 dB, SD 22.1) and was as follows: SME 23.9% and SLWE 36.4%, p = .168. The mean age at implantation was significantly younger only in SLWE patients with preserved hearing (66.9vs80.3 years, p = .008). At 6 months, speech measures were significantly better in all outcomes in HP patients with an SLWE than nonpreserved SLWE patients; this effect abated at 1 year as performance among nonpreserved SLWE patients became equivalent to the remaining cohort. Speech outcomes in SME patients were similar regardless of HP status. Age at implantation and datalogging was correlated with speech outcomes. In this cohort of HP patients, a 1-year functional HP rate of 23.9% (SME) and 36.4% (SLWE) was observed (p = 0.168). This was initially 57.1% (SME) and 70.3% (SLWE) at activation, p = .172. Datalogging and age at implantation were correlated with postoperative speech outcomes.

Insertion Depth and Cochlear Implant Speech Recognition Outcomes: A Comparative Study of 28- and 31.5-mm Lateral Wall Arrays.

1) To compare speech recognition outcomes between cochlear implant (CI) recipients of 28- and 31.5-mm lateral wall electrode arrays, and 2) to characterize the relationship between angular insertion depth (AID) and speech recognition. Retrospective review. Tertiary academic referral center. Seventy-five adult CI recipients of fully inserted 28-mm (n = 28) or 31.5-mm (n = 47) lateral wall arrays listening with a CI-alone device. Cochlear implantation with postoperative computed tomography. Consonant-nucleus-consonant (CNC) word recognition assessed with the CI-alone at 12 months postactivation. The mean AID of the most apical electrode contact for the 31.5-mm array recipients was significantly deeper than the 28-mm array recipients (628° vs 571°, p < 0.001). Following 12 months of listening experience, mean CNC word scores were significantly better for recipients of 31.5-mm arrays compared with those implanted with 28-mm arrays (59.5% vs 48.3%, p = 0.004; Cohen's d = 0.70; 95% CI [0.22, 1.18]). There was a significant positive correlation between AID and CNC word scores (r = 0.372, p = 0.001), with a plateau in performance observed around 600°. Cochlear implant recipients implanted with a 31.5-mm array experienced better speech recognition than those with a 28-mm array at 12 months postactivation. Deeper insertion of a lateral wall array appears to confer speech recognition benefit up to ∼600°, with a plateau in performance observed thereafter. These data provide preliminary evidence of the insertion depth necessary to optimize speech recognition outcomes for lateral wall electrode arrays among CI-alone users.

Advances in hearing preservation in cochlear implant surgery.

Advancements in cochlear implant surgical approaches and electrode designs have enabled preservation of residual acoustic hearing. Preservation of low-frequency hearing allows cochlear implant users to benefit from electroacoustic stimulation, which improves performance in complex listening situations, such as music appreciation and speech understanding in noise. Despite the relative high rates of success of hearing preservation, postoperative acoustic hearing outcomes remain unpredictable. Thin, flexible, lateral wall arrays are preferred for hearing preservation. Both shortened and thin, lateral wall arrays have shown success with hearing preservation and the optimal implant choice is an issue of ongoing investigation. Electrocochleography can monitor cochlear function during and after insertion of the electrode array. The pathophysiology of hearing loss acutely after cochlear implant may differ from that involved in delayed hearing loss following cochlear implant. Emerging innovations may reduce cochlear trauma and improve hearing preservation. Hearing preservation is possible using soft surgical techniques and electrode arrays designed to minimize cochlear trauma; however, a subset of patients suffer from partial to total loss of acoustic hearing months to years following surgery despite evidence of residual apical hair cell function. Early investigations in robotic-assisted insertion and dexamethasone-eluting implants show promise.

Initial Hearing Preservation Is Correlated With Cochlear Duct Length in Fully-inserted Long Flexible Lateral Wall Arrays.

To characterize the relationship between cochlear duct length (CDL) and initial hearing preservation among cochlear implant recipients of a fully inserted 31.5 mm flexible lateral wall electrode array. Retrospective review. Tertiary academic referral center. Adult cochlear implant recipients who presented preoperatively with unaided hearing detection thresholds of ≤ 65 dB HL at 125 Hz and underwent cochlear implantation with a 31.5 mm flexible lateral wall array. Cochlear implantation with a hearing preservation surgical approach. Computed tomography was reviewed to determine CDL. Hearing preservation was characterized by the shift in low-frequency pure-tone average (LFPTA; 125, 250, and 500 Hz), and shift in individual unaided hearing detection thresholds at 125, 250, and 500 Hz. Nineteen patients met the criteria for inclusion. The mean CDL was 34.2 mm (range: 30.8-36.5 mm). Recipients experienced a mean LFPTA shift of 27.6 dB HL (range: 10-50 dB HL). Significant, negative correlations were observed between CDL and smaller threshold shifts at individual frequencies and LFPTA (p ≤ 0.048). A longer CDL is associated with greater likelihood of preserving low-frequency hearing with long arrays. Low-frequency hearing preservation is feasible with fully inserted long flexible arrays within the initial months after cochlear implantation. Preoperative measurement of CDL may facilitate a more individualized approach in array selection to permit optimal cochlear coverage while enhancing hearing preservation outcomes.

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

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). Retrospective review. Tertiary referral center. 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. 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. 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.

Frequency-to-Place Mismatch: Characterizing Variability and the Influence on Speech Perception Outcomes in Cochlear Implant Recipients.

The spatial position of a cochlear implant (CI) electrode array affects the spectral cues provided to the recipient. Differences in cochlear size and array length lead to substantial variability in angular insertion depth (AID) across and within array types. For CI-alone users, the variability in AID results in varying degrees of frequency-to-place mismatch between the default electric frequency filters and cochlear place of stimulation. For electric-acoustic stimulation (EAS) users, default electric frequency filters also vary as a function of residual acoustic hearing in the implanted ear. The present study aimed to (1) investigate variability in AID associated with lateral wall arrays, (2) determine the subsequent frequency-to-place mismatch for CI-alone and EAS users mapped with default frequency filters, and (3) examine the relationship between early speech perception for CI-alone users and two aspects of electrode position: frequency-to-place mismatch and angular separation between neighboring contacts, a metric associated with spectral selectivity at the periphery. One hundred one adult CI recipients (111 ears) with MED-EL Flex24 (24 mm), Flex28 (28 mm), and FlexSOFT/Standard (31.5 mm) arrays underwent postoperative computed tomography to determine AID. A subsequent comparison was made between AID, predicted spiral ganglion place frequencies, and the default frequency filters for CI-alone (n = 84) and EAS users (n = 27). For CI-alone users with complete insertions who listened with maps fit with the default frequency filters (n = 48), frequency-to-place mismatch was quantified at 1500 Hz and angular separation between neighboring contacts was determined for electrodes in the 1 to 2 kHz region. Multiple linear regression was used to examine how frequency-to-place mismatch and angular separation of contacts influence consonant-nucleus-consonant (CNC) scores through 6 months postactivation. For CI recipients with complete insertions (n = 106, 95.5%), the AID (mean ± standard deviation) of the most apical contact was 428° ± 34.3° for Flex24 (n = 11), 558° ± 65.4° for Flex28 (n = 48), and 636° ± 42.9° for FlexSOFT/Standard (n = 47) arrays. For CI-alone users, default frequency filters aligned closely with the spiral ganglion map for deeply inserted lateral wall arrays. For EAS users, default frequency filters produced a range of mismatches; absolute deviations of ≤ 6 semitones occurred in only 37% of cases. Participants with shallow insertions and minimal or no residual hearing experienced the greatest mismatch. For CI-alone users, both smaller frequency-to-place mismatch and greater angular separation between contacts were associated with better CNC scores during the initial 6 months of device use. There is significant variability in frequency-to-place mismatch among CI-alone and EAS users with default frequency filters, even between individuals implanted with the same array. When using default frequency filters, mismatch can be minimized with longer lateral wall arrays and insertion depths that meet the edge frequency associated with residual hearing for CI-alone and EAS users, respectively. Smaller degrees of frequency-to-place mismatch and decreased peripheral masking due to more widely spaced contacts may independently support better speech perception with longer lateral wall arrays in CI-alone users.

Effect of age, electrode array, and time on cochlear implant impedances

Objectives: To determine the impact of age, electrode array, and time on impedance patterns in cochlear implant (CI) patients. Methods: A retrospective case review was performed on 98 patients implanted with the CI24RE perimodiolar (PM) and CI422 lateral wall (LW) arrays between 2010 and 2014 to assess impedances at the 1 week and 3–6 month visit after initial stimulation (IS). Results: With respect to age, impedances were higher in young patients compared to older patients in the middle and apical turns. With time, there were significant reductions in impedances across most electrodes. Electrode array type also had a significant impact on impedance measurements with PM and LW arrays having higher impedances in the basal turn and apical turns, respectively. Furthermore, PM arrays demonstrated significantly lower impedances in the middle and apical turn with time, when compared to LW arrays. Conclusions: Age, electrode array, and time can independently affect CI impedances. Moreover, we show that PM arrays may be advantageous to LW arrays, due to demonstrated lower impedances in the middle and apical turns long term. Understanding the impact of impedance on speech discrimination and determining the intracochlear processes that contribute to differences in impedance are future research directions.

Slim Perimodiolar Arrays Are as Effective as Slim Lateral Wall Arrays for Functional Hearing Preservation After Cochlear Implantation.

To compare functional hearing preservation (HP) with a slim perimodiolar array (SPA) and a slim lateral wall array (SLW) in cochlear implantation (CI). Retrospective chart review. Tertiary referral center. All adult, post-lingual CI recipients with serviceable preoperative hearing serially implanted with SPA or SLW electrodes from July 2015 through July 2018. Cochlear implantation. Hearing preservation (HP). Patients with a low frequency pure-tone average (LFPTA) (125, 250, 500 Hz) threshold less than 80 dB were considered HP candidates based on preoperative audiograms. Postoperative audiograms were obtained before activation. Successful HP was defined as retention of LFPTA less than 80 dB. The change in LFPTA (ΔLFPTA) was also calculated. One hundred twenty one patients were implanted with either the SPA or SLW electrodes, 82 (42,40) of whom were HP candidates with postoperative audiograms. Average (standard deviation, SD) preoperative LFPTA was 54.86 [19.38] and 54.38 [13.58] dB for SLW and SPA respectively, with a mean ΔLFPTA of 24.6 [15.94] and 24.92 [16.66] dB. Successful HP was achieved in 21 (50%) and 22 (55%). Preoperative LFTPA, ΔLFPTA, and postoperative LFPTA were not significantly different (p = 0.89, 0.75, 0.93) between electrodes. The SPA is as effective at immediate functional HP after CI as a SLW.

Potential insertion complications with cochlear implant electrodes

Objectives: The aim of this discussion paper and literature review was to estimate the incidence of a variety of complications associated with the surgical placement of cochlear implant (CI) electrode arrays and to discuss the implications and management of sub-optimal electrode placement. Results: A review of the peer-reviewed literature suggests that the incidence of incomplete electrode insertion and kinking is more prevalent in straight arrays and not more than about 2% in CI recipients with normal cochlear anatomy/patency. Incidence of tip fold-over is greater with perimodiolar arrays but also occurs with straight arrays and is typically less than 5%. Conversely, electrode migration is more common with straight arrays, and high rates (up to 46%) have been reported in some studies. Scalar translocations have also been reported for both perimodiolar and straight arrays. Higher rates have been reported for stylet-based perimodiolar electrodes inserted via cochleostomy (up to 56%), but with much lower rates (<10%) with both sheath-based perimodiolar arrays and lateral wall arrays. Electrode positioning complications represent a significant proportion of perioperative CI complications and compromise the level of benefit from the device. Careful surgical planning and appropriate pre- and intraoperative imaging can reduce the likelihood and impact of electrode positioning complications. There is also evidence that newer array designs are less prone to certain complications, particularly scalar translocation. Conclusions: It is important that implanting surgeons are aware of the impact of sub-optimal electrode placement and the steps that can be taken to avoid, identify and manage such complications.

Intracochlear Electrocochleography: Response Patterns During Cochlear Implantation and Hearing Preservation

Electrocochleography (ECochG) obtained through a cochlear implant (CI) is increasingly being tested as an intraoperative monitor during implantation with the goal of reducing surgical trauma. Reducing trauma should aid in preserving residual hearing and improve speech perception overall. The purpose of this study was to characterize intracochlear ECochG responses throughout insertion in a range of array types and, when applicable, relate these measures to hearing preservation. The ECochG signal in cochlear implant subjects is complex, consisting of hair cell and neural generators with differing distributions depending on the etiology and history of hearing loss. Consequently, a focus was to observe and characterize response changes as an electrode advances. In 36 human subjects, responses to 90 dB nHL tone bursts were recorded both at the round window (RW) and then through the apical contact of the CI as the array advanced into the cochlea. The specific setup used a sterile clip in the surgical field, attached to the ground of the implant with a software-controlled short to the apical contact. The end of the clip was then connected to standard audiometric recording equipment. The stimuli were 500 Hz tone bursts at 90 dB nHL. Audiometry for cases with intended hearing preservation (12/36 subjects) was correlated with intraoperative recordings. Successful intracochlear recordings were obtained in 28 subjects. For the eight unsuccessful cases, the clip introduced excessive line noise, which saturated the amplifier. Among the successful subjects, the initial intracochlear response was a median 5.8 dB larger than the response at the RW. Throughout insertion, modiolar arrays showed median response drops after stylet removal while in lateral wall arrays the maximal median response magnitude was typically at the deepest insertion depth. Four main patterns of response magnitude were seen: increases > 5 dB (12/28), steady responses within 5 dB (4/28), drops > 5 dB (from the initial response) at shallow insertion depths (< 15 mm deep, 7/28), or drops > 5 dB occurring at deeper depths (5/28). Hearing preservation, defined as < 80 dB threshold at 250 Hz, was successful in 9/12 subjects. In these subjects, an intracochlear loss of response magnitude afforded a prediction model with poor sensitivity and specificity, which improved when phase, latency, and proportion of neural components was considered. The change in hearing thresholds across cases was significantly correlated with various measures of the absolute magnitudes of response, including RW response, starting response, maximal response, and final responses (p's < 0.05, minimum of 0.0001 for the maximal response, r's > 0.57, maximum of 0.80 for the maximal response). Monitoring the cochlea with intracochlear ECochG during cochlear implantation is feasible, and patterns of response vary by device type. Changes in magnitude alone did not account for hearing preservation rates, but considerations of phase, latency, and neural contribution can help to interpret the changes seen and improve sensitivity and specificity. The correlation between the absolute magnitude obtained either before or during insertion of the ECochG and the hearing threshold changes suggest that cochlear health, which varies by subject, plays an important role.

Further Evidence of the Relationship Between Cochlear Implant Electrode Positioning and Hearing Outcomes.

Postoperative imaging studies by numerous groups have revealed that final cochlear implant (CI) electrode position impacts audiological outcomes with scalar location consistently shown to be a significant factor. Modiolar proximity has been less extensively studied, and findings regarding the effect of insertion depth have been inconsistent. Using previously developed automated algorithms, we determined CI electrode position in an Institutional Review Board-approved database of 220 CI ears. Generalized linear models (GLM) were used to analyze the relationship between audiological outcomes and factors including age, duration of CI use, device type, and electrode position. For precurved arrays, GLM revealed that scalar position, modiolar proximity, base insertion depth, and sex were significant factors for Consonant-Nucleus-Consonant (CNC) words (R = 0.43, p < 0.001, n = 92 arrays), while scalar position, modiolar proximity, age, and postlingual onset of deafness were significant for Bamford-Kawal-Bench Sentences in Noise (BKB-SIN) (R = 0.51, p < 0.001, n = 85) scores. Other factors were not significant in the final model after controlling for these variables. For straight arrays, we found the insertion depth, postlingual deafness, and length of CI use to be highly significant (R = 0.47, p < 0.001) factors for CNC words (91 arrays), while for BKB-SIN scores the most significant (R = 0.47, p < 0.001) factors were insertion depth, younger age, and postlingual deafness (89 arrays). Our results confirm the significance of electrode positioning in audiological outcomes. The most significant positional predictors of outcome for precurved arrays were full scala tympani (ST) insertion and the modiolar distance, while for the lateral wall arrays the depth of insertion was the most significant factor.

Evaluation of Outcome Variability Associated With Lateral Wall, Mid-scalar, and Perimodiolar Electrode Arrays When Controlling for Preoperative Patient Characteristics.

Determine the impact of electrode array selection on audiometric performance when controlling for baseline patient characteristics. Retrospective evaluation of a prospective cochlear implant (CI) database (January 1, 2012-May 31, 2017). Tertiary Care University Hospital. Three hundred twenty-eight adult CI recipients. Hearing outcomes were measured through unaided/aided pure tone thresholds and speech recognition testing before and after cochlear implantation. All reported postoperative results were performed at least 6 months after CI activation. All device manufacturers were represented. Of the 328 patients, 234 received lateral wall (LW) arrays, 46 received perimodiolar (PM) arrays, and 48 received mid-scalar (MS) arrays. Patients receiving PM arrays had significantly poorer preoperative earphone and aided PTAs and SRTs, and aided Consonant-Nucleus-Consonant(CNC) word and AzBio +10 SNR scores compared with patients receiving LW arrays (all p ≤ 0.04), and poorer PTAs and AzBio +10 SNR scores compared with MS recipients (all p ≤ 0.02). No preoperative audiological variables were found to significantly differ between MS and LW patients. After controlling for preoperative residual hearing and speech recognition ability in a hierarchical multiple regression analysis, no statistically significant difference in audiological outcomes was detected (CNC words, AzBio quiet, or AzBio +10 SNR) among the three electrode array types (all p > 0.05). While previous studies have demonstrated superior postoperative speech recognition scores in LW electrode array recipients, these differences lose significance when controlling for baseline hearing and speech recognition ability. These data demonstrate the proclivity for implanting individuals with greater residual hearing with LW electrodes and its impact on postoperative results.

Challenging aspects of contemporary cochlear implant electrode array design.

ObjectiveA design comparison of current perimodiolar and lateral wall electrode arrays of the cochlear implant (CI) is provided. The focus is on functional features such as acoustic frequency coverage and tonotopic mapping, battery consumption and dynamic range. A traumacity of their insertion is also evaluated.MethodsReview of up-to-date literature.ResultsPerimodiolar electrode arrays are positioned in the basal turn of the cochlea near the modiolus. They are designed to initiate the action potential in the proximity to the neural soma located in spiral ganglion. On the other hand, lateral wall electrode arrays can be inserted deeper inside the cochlea, as they are located along the lateral wall and such insertion trajectory is less traumatic. This class of arrays targets primarily surviving neural peripheral processes. Due to their larger insertion depth, lateral wall arrays can deliver lower acoustic frequencies in manner better corresponding to cochlear tonotopicity. In fact, spiral ganglion sections containing auditory nerve fibres tuned to low acoustic frequencies are located deeper than 1 and half turn inside the cochlea. For this reason, a significant frequency mismatch might be occurring for apical electrodes in perimodiolar arrays, detrimental to speech perception. Tonal languages such as Mandarin might be therefore better treated with lateral wall arrays. On the other hand, closer proximity to target tissue results in lower psychophysical threshold levels for perimodiolar arrays. However, the maximal comfort level is also lower, paradoxically resulting in narrower dynamic range than that of lateral wall arrays. Battery consumption is comparable for both types of arrays.ConclusionsLateral wall arrays are less likely to cause trauma to cochlear structures. As the current trend in cochlear implantation is the maximal protection of residual acoustic hearing, the lateral wall arrays seem more suitable for hearing preservation CI surgeries. Future development could focus on combining the advantages of both types: perimodiolar location in the basal turn extended to lateral wall location for higher turn locations.

Audiological Outcomes and Map Characteristics in Children With Perimodiolar and Slim Straight Array Cochlear Implants in Opposite Ears.

To identify differences in outcomes and map characteristics in pediatric bilateral cochlear implants with modiolar conforming and lateral wall arrays in opposite ears. Retrospective case series. Tertiary care pediatric referral center. Fourteen children who received a perimodiolar array in one ear and a slim straight array in the opposite ear in sequential surgeries. None. Consonant-nucleus-consonant test (CNC) word recognition score, battery life, power levels, electrical compound action potential (ECAP) thresholds, and electrical threshold and comfort charge levels. Speech perception outcomes were poorer in the lateral wall ears than the perimodiolar ears, and scores in the bilateral condition were better than with the lateral wall device alone. Sequential placement was a factor with differences in preoperative candidacy time correlating with greater difference in speech perception. There was no difference in charge levels between ears, in spite of higher ECAP threshold values for the lateral wall devices. While bilateral speech perception was good, speech perception with the lateral wall device alone was poorer. This cannot be explained solely by the device, as differences in preoperative candidacy time were a significant factor. ECAP thresholds are significantly higher for lateral wall electrodes, but that did not translate in to higher psychophysical measurements.