Cochlear Implant Electrode Position Research Articles

Correlation between auditory response telemetry (ART) and computerized tomography measurements in detection of cochlear implant electrode position

Correlation between auditory response telemetry (ART) and computerized tomography measurements in detection of cochlear implant electrode position

The Relation of Cochlear Implant Electrode Array Type and Position on Continued Hearing Preservation.

To analyze the relationship of electrode array (EA) type and position on hearing preservation longevity following cochlear implantation. Retrospective chart review. Tertiary referral center. Adult cochlear implant recipients between 2013 and 2019 with hearing preserved postoperatively and postoperative CT scans. CT scan analysis of EA position. Stepwise regression to determine influence of EA position, EA type, and patient demographics on postoperative low frequency hearing. Low frequency pure tone average (LFPTA), LFPTA shift, angular insertion depth, base insertion depth, scalar position, mean perimodiolar distance. Of 792 cochlear implant recipients, 121 had preoperative LFPTA <80 dB HL with 60 of the 121 (49.6%) implanted with straight, 32 (26.4%) with precurved, styletted, and 29 (24.0%) implanted precurved, nonstyletted EA. Mean follow up was 28.6 months (range 1-103). There was no statistically significant difference in activation, 6- and 12-month, and last follow-up LFPTA (125, 250, and 500 Hz) shift based on EA type (straight p = 0.302, precurved, styletted p = 0.52, precurved, nonstyletted p = 0.77). Preoperative LFPTA and age of implantation were significant predictors of LFPTA shift at activation, accounting for 30.8% of variance ( F [2, 113] = 26.603, p < 0.0001). LFPTA shift at activation, scalar position, and base insertion depth were significant predictors of variability and accounted for 39.1% of variance in LFPTA shift at 6 months ( F [3, 87] = 20.269, p < 0.0001). Only LFPTA shift at 12 months was found to be a significant predictor of LFPTA shift at last follow up, accounting for 41.0% of variance ( F [1, 48] = 32.653, p < 0.0001). Patients had excellent long-term residual hearing regardless of EA type. Age, preoperative acoustic hearing, and base insertion depth may predict short term preservation, while 12-month outcomes significantly predicted long-term hearing preservation.

Quality-assured training in the evaluation of cochlear implant electrode position: a prospective experimental study

BackgroundThe objective of this study was to demonstrate the utility of an approach in training predoctoral medical students, to enable them to measure electrode-to-modiolus distances (EMDs) and insertion-depth angles (aDOIs) in cochlear implant (CI) imaging at the performance level of a single senior rater.MethodsThis prospective experimental study was conducted on a clinical training dataset comprising patients undergoing cochlear implantation with a Nucleus® CI532 Slim Modiolar electrode (N = 20) or a CI512 Contour Advance electrode (N = 10). To assess the learning curves of a single medical student in measuring EMD and aDOI, interrater differences (senior–student) were compared with the intrarater differences of a single senior rater (test–retest). The interrater and intrarater range were both calculated as the distance between the 0.1th and 99.9th percentiles. A “deliberate practice” training approach was used to teach knowledge and skills, while correctives were applied to minimize faulty data-gathering and data synthesis.ResultsIntrarater differences of the senior rater ranged from − 0.5 to 0.5 mm for EMD and − 14° to 16° for aDOI (respective medians: 0 mm and 0°). Use of the training approach led to interrater differences that matched this after the 4th (EMD) and 3rd (aDOI) feedback/measurement series had been provided to the student.ConclusionsThe training approach enabled the student to evaluate the CI electrode position at the performance level of a senior rater. This finding may offer a basis for ongoing clinical quality assurance for the assessment of CI electrode position.

Use of Cone Beam Computed Tomography to Assess Cochlear implant Electrode Position with Correlation to Performance.

Aim: Cone Beam Computed Tomography (CBCT) has been used in a variety of maxillodental applications and recently, it has proved to be effective in the otorhinolaryngology field. In this study, we used CBCT for assessment of scalar location, insertion length and distance between the cochlear implant electrode array and modiolus and correlate these factors to speech performance.Materials & Methods: This study was carried out on 30 children with bilateral severe to profound prelingual sensorineural hearing loss that had undergone cochlear implantation. Radiological assessment of electrode arrays position using CBCT was performed and correlated with speech recognition score..Results: CBCT revealed that the electrode array was inserted in the scala tympani in 26/30 children (86.66%) and showed better speech recognization score than scala vestibule insertion. The mean distance between the modiolus and electrode arrays was 0.53 ± 0.11 mm and the average length of insertion was 21.49 ± 3.65mm. Distance between the electrode array and modiolus was negatively correlated to audiological performance in all patients. Pearson test showed a statistically significant positive correlation between insertion length and speech recognition score. Conclusion: CBCT is very effective in localizing cochlear implant electrode arrays. Depth of insertion and closer distance to modiolus are associated with statistically better speech outcome.

The effect of the cochlear implant electrode position on the neural response telemetry results: A prospective clinical trial at a single center

Aim: This study aims to investigate the changes in the post-op NRT thresholds of two different implant electrodes of the same brand positioned laterally within the scala tympani, and the pre-modiolar locations, using the same round window approach.Material and Methods: After CI operation NRT measurements conducted at different times on the Nucleus® CI422 nucleus slim straight and Nucleus® CI24RE electrode types of two different electrode models.Results: The number of patients who received the Nucleus® CI24RE (ST) electrode and the Nucleus® CI422 nucleus slim straight were 26 (33.3%) and 56 (66.7%), respectively. NRT values tended to decrease from the basal part of cochlea towards an apex at any time of evaluation in both types of cochlear implants. Conclusion: There was a difference between Nucleus® CI24RE and Nucleus® CI422 nucleus slim straight groups in terms of NRT thresholds. Nucleus® CI422 nucleus slim straight electrode yielded lower NRT threshold levels.

Evaluation of Multi-Slice Computed Tomography in Assessment of Cochlear Implant Electrode Position: A Pictorial Essay

Cochlear implant has become the standard therapy to rehabilitate patients with severe to profound bilateral sensorineural hearing loss. The position of the electrode in the scala and the depth of its insertion have been shown to be predicting factors of hearing outcomes. This article serves to review the multi-slice computed tomography imaging characteristics and appearance of cochlear implant, their exact position and the depth of insertion in children who underwent cochlear implant surgery. Moreover, in order to evaluate the impact of the electrode position on clinical results following cochlear implant surgery, in this study we also compared the findings on the electrode location with the results of audiometry of children after one year of follow up. Finding the best location for the electrode results in better audiometric outcomes.

Intraoperative Electrophysiologic Variations Caused by the Scalar Position of Cochlear Implant Electrodes.

The position of cochlear implant (CI) electrodes in the cochlea is fundamental for the interaction between the implant and the neurons of the spiral ganglion. The scalar position of the electrode in the cochlea is assumed to be an important parameter for the clinical outcome. In our study, the intraoperative electrophysiologic characteristics in dependence of the position of CI electrodes in the scala tympani or in the scala vestibuli after scalar change should be determined. The intraoperative impedances and neural response telemetry (NRT) data of 23 patients implanted with a Nucleus Advance Contour (Cochlear Pty, Sydney, Australia) electrode were recorded. One CI surgeon and two radiologists evaluated the electrode array's position independently radiologically by flat-panel tomography. Results from 17 patients with the electrode positioned in the scala tympani and six patients with the electrode changing intraoperatively from the tympanic into the vestibular scala were retrospectively analyzed. We found a statistically significant difference with an NRT threshold-based ratio for the groups. An estimation of the (radiologically confirmed) scalar position based on the NRT ratio was possible retrospectively. The evaluation of specific intraoperative electrophysiologic data allowed separating between a regular and an irregular (i.e., scalar changing) position of CI electrodes. This noninvasive methodology can support the postoperative radiologic evaluation of the CI electrode array position.

The Influence of Cochlear Implant Electrode Position on Performance

Objectives: To study the relation between variables related to cochlear implant electrode position and speech perception performance scores in a large patient population. Design: The study sample consisted of 203 patients implanted with a CII or HiRes90K implant with a HiFocus 1 or 1J electrode of Advanced Bionics. Phoneme and word score averages for the 1- and 2-year follow-up were calculated for 41 prelingually deaf and 162 postlingually deaf patients. Analyses to reveal correlations between these performance outcomes and 6 position-related variables (angle of most basal electrode contact, surgical insertion angle, surgical insertion, wrapping factor, angular insertion depth, linear insertion depth) were executed. The scalar location, as an indication for the presence of intracochlear trauma, and modiolus proximity beyond the basal turn were not evaluated in this study. In addition, different patient-specific variables (age at implantation, age at onset of hearing loss, duration of deafness, preoperative phoneme and word scores) were tested for correlation with performance. Results: The performance scores of prelingual patients were correlated with age at onset of hearing loss, duration of deafness and preoperative scores. For the postlingual patients, performance showed correlations with all 5 patient-specific variables. None of the 6 position-related variables influenced speech perception in cochlear implant patients. Conclusions: Although several patient-specific variables showed correlations with speech perception outcomes, not one of the studied angular and linear position-related variables turned out to have a demonstrable influence on performance.

Relationship between intracochlear electrode position and tinnitus in cochlear implantees

Conclusion: Cochlear implant electrode position has an impact on the rate of tinnitus suppression and generation. Objective: Suppression of pre-operative tinnitus or a generation of a new tinnitus in cochlear implantees is a known effect of cochlear implantation. The aim of the current study was to evaluate different cochlear implant electrode positions and their relationship with tinnitus suppression and tinnitus generation. Method: This study retrospectively evaluated four groups of CI recipients with radiologically evaluated electrode positions in relation to their subjective tinnitus quality, as evaluated by an analogue loudness scale (ALS) and a questionnaire. Group 1 consisted of 19 patients with a scalar change of the electrode position. Group 2 consisted of 18 patients with a scala tympani position and a perimodiolar electrode. Group 3 consisted of 10 patients with a scala tympani position and a lateral wall electrode. Group 4 consisted of eight patients with a scala vestibuli position. Results: An overall tinnitus suppression rate of 45.9% and a generation of a new tinnitus or the deterioration of an existing one of 5.6% were observed. A significant difference in tinnitus suppression was found between groups 1 and groups 2, 3, and 4 in tinnitus suppression and tinnitus generation.

The use of cone-beam computed tomography to determine cochlear implant electrode position in human temporal bones.

To assess the utility of cone-beam computed tomography (CBCT) imaging in the estimation of cochlear implant (CI) electrode position in implanted temporal bones. Eight fresh frozen temporal bones were mounted and oriented as for standard surgery and were implanted with Cochlear Slim-Straight (SS) or Contour Advance electrode arrays by 2 CI surgeons. The bones were then imaged using an Accuitomo F170 CBCT scanner (isometric 250 μm voxel size) and were then processed for histologic sectioning (500 μm sections). The CBCT images and the histologic micrographs (providing the "gold standard") were examined independently by several observers who assessed the scalar position (tympani or vestibuli) of each electrode in each temporal bone specimen. Examination of the histologic micrographs confirmed that all electrodes were positioned within the scala tympani in all 8 bones. Similar judgments were made by the observers rating the CBCT images, except that one of the 2 observers estimated some of the apical electrodes to be located in the scala vestibuli in two of the bones implanted with the SS electrode. Cone-beam CT imaging is able to provide a good indication of the scalar position of implanted electrodes, although estimation may be slightly less reliable for apical electrodes and for straight electrode designs. Additional advantages of using CBCT for this purpose are shorter acquisition time and reduction of radiation dose as compared with conventional CT.

Diversity in Cochlear Morphology and Its Influence on Cochlear Implant Electrode Position

To define a minimal set of descriptive parameters for cochlear morphology and study its influence on the cochlear implant electrode position in relation to surgical insertion distance. Cochlear morphology and electrode position were analyzed using multiplanar reconstructions of the pre- and postoperative CT scans in a population of 336 patients (including 26 bilaterally implanted ones) with a CII HiFocus1 or HiRes90K HiFocus1J implant. Variations in cochlear diameter and cochlear canal size were analyzed. The relationship between the outer and inner walls was investigated. Size differences based on sex, age, and ear side were investigated using linear mixed models. Two new methods, spiral fitting and principal component analysis, were proposed to describe cochlear shape, and the goodness of fit was investigated. The relationship between cochlear shape and electrode position, in terms of modiolus proximity and insertion depth, was analyzed using clustering, one-way analysis of variance (ANOVA) and simple linear regression analysis. Large variations in cochlear morphology were found, with cochlear canal sizes ranging from 0.98 to 2.96 mm and average cochlear diameters between 8.85 and 5.92 mm (with standard deviations of around 0.4 mm). The outer and inner walls were significantly correlated (p < 0.01), and a size difference of 4% in favor of males was found. Spiral fitting shows good alignment of the true measurements, with residuals having a mean of 0.01 mm and a standard deviation of 0.29 mm. Principal component analysis (PCA) showed that the use of one component, which describes size, is sufficient to explain 93.6% of the cochlear shape variance. A significant sex difference was also found with spiral fitting and PCA. Cochlear size was found to have a significant influence on modiolus proximity and insertion depth of the electrode (p < 0.01). Cochlear size explained around 13% of the variance in electrode position. When cochlear size was combined with surgical insertion, more than 81% of the variance in insertion depth can be explained. This study demonstrates a large variety in cochlear morphology, which significantly impacts electrode position in terms of modiolus proximity and insertion depth. The effect size is, however, relatively small compared with surgical insertion distance. PCA is shown to be an accurate reduction method for describing cochlear shape.

Evaluation of cochlear implant electrode position after a modified round window insertion by means of a 64-multislice CT

Conclusion. The modified round window insertion enables reproducible insertion into the scala tympani as demonstrated by comparing the 64-CT scanning data and the surgeon's reports. Objective. To estimate the postoperative cochlear implant electrode position using a modified round window approach. Patients and methods. In a prospective study, 82 patients were operated via a modified round window approach to insert primarily into the scala tympani. Surgery had been performed from 2005 to 2008, implanting a Nucleus Freedom RECA device (Cochlear Corp.) (n=43) or 90 k Helix device (Advanced Bionics Corp.) (n=39). The array localization within the cochlea was determined by axial scanning overview, digital reconstruction of a 64-slice CT and by evaluation of the surgeon's report. Results. In 78 (95.1%) patients, the array could be located in the scala tympani. In four cases, the position of the electrode was changed intracochlearly from the scala tympani to the scala vestibuli. In three additional cases, the scala vestibuli was inserted intentionally because the tympanic scale was found to be obstructed intraoperatively due to ossification. There were no significant differences between the intraoperative positioning and postoperative localization of the electrode arrays of the two manufacturers.

Is There a Relation between Speech Recognition and the Position of Cochlear Implant Electrodes in the Inner Ear?

Is There a Relation between Speech Recognition and the Position of Cochlear Implant Electrodes in the Inner Ear?