Early activation after cochlear implantation: a systematic review.

PURPOSE: To systematically review the outcomes of early activation following cochlear implantation (CI) based on the findings from different studies in the literature. METHODS: A comprehensive search strategy was conducted through different databases to identify relevant articles. Our outcomes included impedance levels, rates of complications, hearing and speech perception performance, and patients' satisfaction levels. RESULTS: The total number of included studies in this systematic review is 19, which recruited 1157 patients, including 857 who underwent early activation following CI. Seventeen studies investigated impedance levels or feasibility rates of early activation approaches. Most of these studies (n = 10) reported that mean impedance levels remarkably decreased within the first day-to-month (first measurement) post-activation. In addition, all 17 studies showed that impedance levels finally normalize and become comparable with intraoperative levels or the conventional activation group. Seventeen studies reported the occurrence of complications in their population. Ten of these studies indicated that none of their patients developed any post-operative complications after early activation. Seven studies reported the development of some minor complications, including pain 9.2% (28/304), infection 4.7% (13/275), swelling 8.2% (25/304), vertigo 15.1% (8/53), skin hyperemia 2.2% (5/228), and others 16.4% (9/55). Hearing and speech perception was assessed in six studies, which showed a remarkable improvement in their patients. Three studies investigated patients' satisfaction and showed high satisfaction levels. Only one report investigated the economic advantages of early activation. CONCLUSION: Early activation is safe and feasible and does not impact the hearing and speech outcomes of the patients undergoing CI procedures.

Auditory Performance and Subjective Satisfaction with the ADHEAR System.

BACKGROUND: The ADHEAR device, a new nonsurgical bone conduction hearing device, has been developed for patients with conductive hearing loss. OBJECTIVES: This study aims to assess the impact of the ADHEAR device on the audiological performance and satisfaction level in subjects with conductive hearing loss. METHODS: Twelve patients with conductive hearing loss were included. All patients received the device for 3 months. The audiological outcomes were determined using basic audiological assessments, including pure tone audiometry and sound field measurements of pure tone and speech audiometry with the contralateral ear occluded with a specific earplug. Additionally, the patients were subjectively evaluated using (1) the Speech, Spatial, and Qualities Questionnaire (SSQ), and (2) the custom-made ADHEAR questionnaire. RESULTS: Analysis of the measured audiological outcomes revealed an average improvement in pure tone thresholds (functional gain) of 23 (± 4.4) dB HL when the ADHEAR system was used compared to the unaided condition in the sound field. Moreover, speech reception thresholds improved by an average of 23 (± 15.3) dB SPL in the aided condition with plugged contralateral ear. Additionally, when using ADHEAR in the sound field, subjects' speech recognition scores improved by 32% (± 17.7) in quiet and 21% (± 15.1) in the presence of interfering noise. The average SSQ questionnaire scores improved from 3.9 at the study initiation to 6.6 after 3 months of device usage. ADHEAR custom questionnaire assessments revealed high satisfaction and acceptance of the device with no pain or skin irritation. CONCLUSION: During the study period, this new adhesive system yielded improved audiological outcomes with high patient satisfaction and acceptance and no reported skin irritation or pain.

Feasibility of one-day activation in cochlear implant recipients.

OBJECTIVE: To determine if cochlear implants recipients can be safely and effectively fitted with their sound processor one day after their implant surgery. DESIGN: All subjects were implanted with MED-EL Concerto cochlear implant. Subjects' electrode impedance levels, maximum comfortable levels, and threshold levels were measured one day after surgery and compared to measurements obtained one month post implantation using the non-parametric Wilcoxon signed-rank test. STUDY SAMPLE: Twenty-nine participants in the age range of 1 to 42 years (average of 5 years). RESULTS: No adverse events were reported post-operatively. Measures after one day of surgery were significantly less than those measured one month post implantation. CONCLUSION: Early activation of the implant did not impact the healing process of the incision site, suggesting that one-day activation of the implant is feasible for some patients when medically possible. The evolution of the impedance and stimulation levels were consistent with that reported in previous studies, which indicates that early activation did not interfere with the physiological changes taking place after implantation.

Cochlear implantation in pediatrics: Impact of newborn hearing screening on intervention time.

OBJECTIVES: The newborn hearing screening (NHS) program was globally established for early hearing loss (HL) identification and intervention. Early intervention is essential to minimize or prevent the negative consequences of HL. In Saudi Arabia, the NHS was officially implemented in 2016. Currently, its impact on the timing of cochlear implantations (CIs) in Saudi Arabia remains unclear, and information on potential hospital-related delays affecting early implantation is lacking. Thus, this study aimed to evaluate the effect of implementing the NHS on age at CI in children with prelingual deafness in a CI center in Saudi Arabia, and to evaluate the hospital timing in the CI process. METHODS: All pediatric CI users who presented for the first time to the CI committee (CIC) at a tertiary center and received their implants between 2015 and 2022 were enrolled in this study. Date of birth (DOB), date of presentation to the CI committee (DOCIC), and date of CI surgery (DOCIS) were retrospectively reviewed. RESULTS: In total, 304 CI children were included in the analysis. Approximately 55 % of the children (n = 167) were screened for HL through the NHS, whereas 45 % of the children (n = 137) were born before the launch of the NHS. Both age at the presentation to the CIC (i.e. difference between DOCIC and DOB) and age at implantation (i.e. difference between DOCIS and DOB) were significantly earlier in children who were screened for HL through the NHS than those who were not screened (P < 0.0001). The time difference between the DOCIC and DOCIS was not significantly different between the screened and unscreened children (P > 0.05). CONCLUSION: The implementation of the NHS in the tertiary center has a significant positive effect on age at presentation to the CIC and age at implantation, but not on the actual CI surgery. Further research is needed to reduce the hospital delays before the actual surgery in order to increase the likelihood of children receiving implantation early in their life.

Cochlear Implantation: Long-Term Effect of Early Activation on Electrode Impedance.

Objectives: The growing adoption of cochlear implants (CIs) necessitates understanding the factors influencing long-term performance and improved outcomes. This work investigated the long-term effect of early activation of CIs on electrode impedance in a large sample of CI users at different time points. Methods: A retrospective study on 915 ears from CI patients who were implanted between 2015 and 2020. According to their CI audio processor activation time, the patients were categorized into early activation (activated 1 day after surgery, n = 481) and classical activation (activated 4 weeks after surgery, n = 434) groups. Then, the impact of the activation times on the electrode impedance values, along the electrode array contacts, at different time points up to two years was studied and analyzed. Results: The early activation group demonstrated lower impedance values across all the electrode array sections compared to the classical activation at 1 month, 1 year, and 2 years post-implantation. At 1 month, early activation was associated with a reduction of 0.34 kΩ, 0.46 kΩ, and 0.37 kΩ in the apical, middle, and basal sections, respectively. These differences persisted at subsequent intervals. Conclusions: Early activation leads to sustained reductions in the electrode impedance compared to classical activation (CA), suggesting that earlier activation might positively affect long-term CI outcomes.

A novel method for evaluating mastoid defect regrowth after cochlear implantation.

This retrospective study examined mastoid defects resulting from cochlear implant (CI) surgery and their potential for spontaneous regrowth across different age groups. Spontaneous closure of mastoid defects has been observed in certain CI patients during revision surgery or through post-operative temporal bone computer tomography (TB-CT). The analysis encompassed 123 CI recipients, comprising 81.3% children and 18.7% adults, who underwent post-operative TB-CT scans. Using image adjustment software, the study measured mastoid defect areas and found a significant reduction in children's defects between the initial and subsequent scans. Notably, mastoid defect areas differed significantly between children and adults at both time points. Furthermore, the analysis revealed significant correlations between mastoid defect areas and the age at implantation as well as the time elapsed since the CI surgery and the first CT scan. This study provides valuable insights for evaluating CI patients scheduled for revision surgery by assessing potential surgical challenges and duration. Furthermore, it may have a pivotal role in evaluating patients who experience postauricular swelling subsequent to CI surgery.

A novel radiological software prototype for automatically detecting the inner ear and classifying normal from malformed anatomy.

BACKGROUND: To develop an effective radiological software prototype that could read Digital Imaging and Communications in Medicine (DICOM) files, crop the inner ear automatically based on head computed tomography (CT), and classify normal and inner ear malformation (IEM). METHODS: A retrospective analysis was conducted on 2053 patients from 3 hospitals. We extracted 1200 inner ear CTs for importing, cropping, and training, testing, and validating an artificial intelligence (AI) model. Automated cropping algorithms based on CTs were developed to precisely isolate the inner ear volume. Additionally, a simple graphical user interface (GUI) was implemented for user interaction. Using cropped CTs as input, a deep learning convolutional neural network (DL CNN) with 5-fold cross-validation was used to classify inner ear anatomy as normal or abnormal. Five specific IEM types (cochlear hypoplasia, ossification, incomplete partition types I and III, and common cavity) were included, with data equally distributed between classes. Both the cropping tool and the AI model were extensively validated. RESULTS: The newly developed DICOM viewer/software successfully achieved its objectives: reading CT files, automatically cropping inner ear volumes, and classifying them as normal or malformed. The cropping tool demonstrated an average accuracy of 92.25%. The DL CNN model achieved an area under the curve (AUC) of 0.86 (95% confidence interval: 0.81-0.91). Performance metrics for the AI model were: accuracy (0.812), precision (0.791), recall (0.8), and F1-score (0.766). CONCLUSION: This study successfully developed and validated a fully automated workflow for classifying normal versus abnormal inner ear anatomy using a combination of advanced image processing and deep learning techniques. The tool exhibited good diagnostic accuracy, suggesting its potential application in risk stratification. However, it is crucial to emphasize the need for supervision by qualified medical professionals when utilizing this tool for clinical decision-making.

Amplitude Parameters Are Predictive of Hearing Preservation in a Randomized Controlled Trial of Intracochlear Electrocochleography During Cochlear Implant Surgery.

OBJECTIVE: To prospectively evaluate the association between hearing preservation after cochlear implantation (CI) and intracochlear electrocochleography (ECochG) amplitude parameters. STUDY DESIGN: Multi-institutional, prospective randomized clinical trial. SETTING: Ten high-volume, tertiary care CI centers. PATIENTS: Adults (n = 87) with sensorineural hearing loss meeting CI criteria (2018-2021) with audiometric thresholds of ≤80 dB HL at 500 Hz. METHODS: Participants were randomized to CI surgery with or without audible ECochG monitoring. Electrode arrays were inserted to the full-depth marker. Hearing preservation was determined by comparing pre-CI, unaided low-frequency (125-, 250-, and 500-Hz) pure-tone average (LF-PTA) to LF-PTA at CI activation. Three ECochG amplitude parameters were analyzed: 1) insertion track patterns, 2) magnitude of ECochG amplitude change, and 3) total number of ECochG amplitude drops. RESULTS: The Type CC insertion track pattern, representing corrected drops in ECochG amplitude, was seen in 76% of cases with ECochG "on," compared with 24% of cases with ECochG "off" ( p = 0.003). The magnitude of ECochG signal drop was significantly correlated with the amount of LF-PTA change pre-CI and post-CI ( p < 0.05). The mean number of amplitude drops during electrode insertion was significantly correlated with change in LF-PTA at activation and 3 months post-CI ( p ≤ 0.01). CONCLUSIONS: ECochG amplitude parameters during CI surgery have important prognostic utility. Higher incidence of Type CC in ECochG "on" suggests that monitoring may be useful for surgeons in order to recover the ECochG signal and preventing potentially traumatic electrode-cochlear interactions.

Cochlear Implantation: The use of OTOPLAN Reconstructed Images in Trajectory Identification.

OBJECTIVES: This study aimed to define the best electrode trajectory line in cochlear implant (CI) surgery using the OTOPLAN (otology planning software) reconstructed 3D model and to investigate the surgical distance of the retro-facial approach as a direct access to the round window. METHODS: Computed tomography (CT) scans of the normal temporal bone were included for analysis in this study. OTOPLAN reconstruction was used to build 3D models with specific ear structures for study analysis. RESULTS: Twenty-five scans were included; the average age at the time of CT scan was 6.8±12 years. Twelve scans (48%) were right-sided and thirteen (52%) were left-sided. The best trajectory line to the round window was identified in all scans. The retro-facial approach was the optimal approach for 52% of cases (13/25). In all scans, the safe distance from the facial nerve were in favor of the retro-facial approach (P = 0.0011). CONCLUSION: The OTOPLAN reconstructed imaging provided a good analysis of the retro-facial approach and helped in planning the surgical trajectory line towards the round window. Additionally, calculation of the surgical distance can help the surgeon compare the retro-facial approach to the standard facial recess for preoperative planning. These findings may help in robotic surgery.

Method to estimate the basal turn length in inner ear malformation types.

The mathematical equations to estimate cochlear duct length (CDL) using cochlear parameters such as basal turn diameter (A-value) and width (B-value) are currently applied for cochleae with two and a half turns of normal development. Most of the inner ear malformation (IEM) types have either less than two and a half cochlear turns or have a cystic apex, making the current available CDL equations unsuitable for cochleae with abnormal anatomies. Therefore, this study aimed to estimate the basal turn length (BTL) from the cochlear parameters of different anatomical types, including normal anatomy; enlarged vestibular aqueduct; incomplete partition types I, II, and III; and cochlear hypoplasia. The lateral wall was manually tracked for 360° of the angular depth, along with the A and B values in the oblique coronal view for all anatomical types. A strong positive linear correlation was observed between BTL and the A- (r2 = 0.74) and B-values (r2 = 0.84). The multiple linear regression model to predict the BTL from the A-and B-values resulted in the following equation (estimated BTL = [A × 1.04] + [B × 1.89] - 0.92). The manually measured and estimated BTL differed by 1.12%. The proposed equation could be beneficial in adequately selecting an electrode that covers the basal turn in deformed cochleae.

Cochlear Implantation: The Volumetric Measurement of Vestibular Aqueduct and Gusher Prediction.

This study aimed to validate the role of 3D segmentation in measuring the volume of the vestibular aqueduct (VAD), and the inner ear, and to study the correlation between VAD volume and VAD linear measurements at the midpoint and operculum. The correlation with other cochlear metrics was also studied. We retrospectively recruited 21 children (42 ears) diagnosed with Mondini dysplasia (MD) plus enlarged vestibular aqueduct (EVA) from 2009 to 2021 and who underwent cochlear implantation (CI). Patients' sociodemographic data were collected, and linear cochlear metrics were measured using Otoplan. Vestibular aqueduct width and vestibular aqueduct and inner ear volumes were measured by two independent neuro-otologists using 3D segmentation software (version 4.11.20210226) and high-resolution CT. We also conducted a regression analysis to determine the association between these variables and CT VAD and inner ear volumes. Among the 33 cochlear implanted ears, 13 ears had a gusher (39.4%). Regarding CT inner ear volume, we found that gender, age, A-value, and VAD at the operculum were statistically significant (p-Value = 0.003, <0.001, 0.031, and 0.027, respectively) by regression analysis. Moreover, we found that Age, H value, VAD at the midpoint, and VAD at the operculum were significant predictors of CT VAD volume (p-Value < 0.04). Finally, gender (OR: 0.092; 95%CI: 0.009-0.982; p-Value = 0.048) and VAD at the midpoint (OR: 0.106; 95%CI: 0.015-0.735; p-Value = 0.023) were significant predictors of gusher risk. Patients' gusher risk was significantly differentiated by gender and VAD width at the midpoint.

Enhancing cochlear duct length estimation by incorporating second-turn parameters.

Estimating insertion depth, cochlear duct length (CDL), and other inner ear parameters is vital to optimizing cochlear implantation outcomes. Most current formulas use only the basal turn dimensions for CDL prediction. In this study, we investigated the importance of the second turn parameters in estimating CDL. Two experienced neuro-otologists blindly used segmentation software to measure (in mm) cochlear parameters, including basal turn diameter (A), basal turn width (B), second-turn diameter (A2), second-turn width (B2), CDL, first-turn length, and second-turn length (STL). These readings were taken from 33 computed tomography (CT) images of temporal bones from anatomically normal ears. We constructed regression models using A, B, A2, and B2 values fitted to CDL, two-turn length, and five-fold cross-validation to ensure model validity. CDL, A value, and STL were longer in males than in females. The mean B2/A2 ratio was 0.91 ± 0.06. Adding A2 and B2 values improved CDL prediction accuracy to 86.11%. Therefore, we propose a new formula for more accurate CDL estimation using A, B, A2, and B2 values. In conclusion, the findings of this study revealed a notable improvement in the prediction of two-turn length (2TL), and CDL by clinically appreciable margins upon adding A2 and B2 values to the prediction formulas.

Cochlear Implant Single-Unit Audio Processors in Young Children.

BACKGROUND: RONDO 2 is a lightweight, compact, wirelessly charged, and fully integrated single-unit speech processor. Single-unit processors provide an effective and convenient alternative to behind-the-ear processors for adults. Therefore, the aim of this study was to investigate if RONDO 2 is suitable for and did not compromise the hearing performance of young children in everyday life. METHODS: Thirteen children aged -lt;4 years were fitted with the RONDO 2 speech processor at the first activation of the cochlear implant. They were evaluated with the LittlEARS® Auditory Questionnaire, LittlEARS® Early Speech Production Questionnaire, and the Speech, Spatial, and Qualities of Hearing Scale 12 pre-implantation. In addition to these measures, they were evaluated with the Audio Processor Satisfaction Questionnaire post-implantation. Duration of daily use and troubleshooting data were acquired. Evaluation occurred at 4 time points: before implantation and 1, 3, and 12 months post-initial activation. RESULTS: Ten out of 13 children continued using RONDO 2 after the study. Twelve months after implantation, they used it on average 11.6 hours per day and had an average Audio Processor Satisfaction Questionnaire score of 9.1 out of 10. Average hearing performance scores continuously improved throughout the follow-up period across measures. Twelve months after implantation, the mean scores were 30.1 out of 35 for the LittlEARS® Auditory Questionnaire, 19.9 out of 27 for the LittlEARS® Early Speech Production Questionnaire, and 7.4 out of 10 for the Speech, Spatial, and Qualities of Hearing Scale 12. CONCLUSION: Participants demonstrated high levels of satisfaction and good hearing performance with RONDO 2, which indicates that this single-unit processor could be a viable and comfortable alternative to behind-the-ear processors in young children, although larger controlled experiments are warranted.

Cochlear Implantation in Pediatrics: The Effect of Cochlear Coverage.

The effect of insertion depth and position of cochlear implant (CI) electrode arrays on speech perception remains unclear. This study aimed to determine the relationship between cochlear coverage and speech performance in children with prelingual hearing loss with CI. Pure tone audiometry (PTA) and speech audiometry, including speech reception threshold (SRT) using spondee words and speech discrimination score (SDS) using phonetically balanced monosyllabic words, were tested. The Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scales were also used. Thirty-one ears were implanted with the FLEX 28 electrode array, and 54 with the FORM 24 were included in the current study. For the studied ear, the mean cochlear duct length was 30.82 ± 2.24 mm; the mean cochlear coverage was 82.78 ± 7.49%. Cochlear coverage was a significant negative predictor for the mean pure tone threshold across frequecnies of 0.5, 1, 2, and 4 kHz (PTA4) (p = 0.019). Cochlear coverage was a significant positive predictor of SDS (p = 0.009). In children with cochlear coverage ≥ 82.78%, SDS was significantly better than in those with coverage < 82.78% (p = 0.04). Cochlear coverage was not a significant predictor of the SRT, CAP, or SIR. In conclusion, the cochlear coverage of the CI electrode array has an impact on the users' SDS. Further long-term studies with larger sample sizes should be conducted to address the most critical factors affecting CI recipients' outcomes.

A Literature Review on Cochlear Implant Activation: From Weeks to Hours.

Objectives: The present literature review discusses the chronological evolution of Cochlear Implant (CI) activation and its definition among the relevant studies in the literature. In addition, the benefits of standardizing the early activation process in implantation centers worldwide are discussed. Methods: A comprehensive literature search was conducted in the major databases such as PubMed, Scopus, and Embase to retrieve all the relevant articles that reported early activation approaches following CI. Results: The evolution of the timing of early activation after CI has been remarkable in the past few years. Some studies reported the feasibility of early activation 1 day after the CI surgery in their users. Conclusions: Within the last decade, some studies have been published to report the feasibility and outcomes of its early activation. However, the process of early activation was not adequately defined, and no apparent guidelines could be found in the literature.

Pregnancy-Related Giant Nasal Mass: A Diagnostic Dilemma.

SIGNIFICANCE STATEMENT: Pregnancy-related giant nasal masses often present a diagnostic challenge and clinical dilemma due to the obvious restrictions in utilizing imaging and general anesthesia during pregnancy. Therefore, we highlight the importance of clinical judgment, especially during pregnancy, and should not disregard certain clinical cues. In addition, we recommend an in-office polypectomy for giant nasal polyps worsening during pregnancy and nasal steroids to optimize their quality of life while avoiding systemic medications or further interventions.

Changes in the Area Adjacent to the Internal Receiver-Stimulator of Cochlear Implant: A Retrospective Study.

BACKGROUND: In some patients with cochlear implants, bony resorption at the internal receiver- stimulator site can be observed on postoperative computed tomography. Therefore, it is essential to elucidate the effects of the internal receiver-stimulator on the scalp and bony bed over time. OBJECTIVE: We aimed to evaluate how the internal receiver-stimulator of a cochlear implant device changed the thickness of the surrounding scalp and skull over time using computed tomography. METHODS: This retrospective study evaluated patients who underwent cochlear implantation and received two computed tomography scans postoperatively for different indications at a tertiary referral centre. The main outcomes were scalp thickness and bony bed depth. RESULTS: Fourteen ears were included in this study. There was very good inter-rater reliability among the two readers who evaluated the computed tomography of the included patients, with a Cronbach's alpha of 0.94. The mean scalp thickness over the internal receiver-stimulator was 6.02 (+/-2.4) mm in the first scan and decreased with no significant change to 5.62 mm (+/-1.64) in the second scan (p = 0.59, paired t-test). The mean depth of the bony bed increased significantly from 1.39 mm (+/-0.93) to 2.62 mm (+/-1.24) (p = 0.03). CONCLUSION: There was no change in the thickness of the scalp overlying the internal receiver-stimulator indicating that the scalp was more resistant than the bony skull to the tensile pressure exerted by the internal receiver-stimulator. In contrast, the bony bed depth of the internal receiver-stimulator increased over time. This can result in decreased internal receiver-stimulator protrusion and decreased risk of device displacement and migration.

A Machine Learning Model to Predict Citation Counts of Scientific Papers in Otology Field.

One of the most widely used measures of scientific impact is the number of citations. However, due to its heavy-tailed distribution, citations are fundamentally difficult to predict but can be improved. This study was aimed at investigating the factors and parts influencing the citation number of a scientific paper in the otology field. Therefore, this work proposes a new solution that utilizes machine learning and natural language processing to process English text and provides a paper citation as the predicted results. Different algorithms are implemented in this solution, such as linear regression, boosted decision tree, decision forest, and neural networks. The application of neural network regression revealed that papers' abstracts have more influence on the citation numbers of otological articles. This new solution has been developed in visual programming using Microsoft Azure machine learning at the back end and Programming Without Coding Technology at the front end. We recommend using machine learning models to improve the abstracts of research articles to get more citations.

Mastoid Growth and the Configuration of Cochlear Implant Electrode Lead.

OBJECTIVES: To study the changes in the coiled configuration of electrode excess lead in the mastoid cavity in the cochlear implant recipients over time. METHODS: Post-operative CT scans at two different appointments of fourteen patients with cochlear implants (CI) were retrospectively analyzed using a DICOM viewer software (3D-slicer). Mastoid thickness (MT) was measured in the oblique coronal plane from the round window (RW) entrance to the mastoid edge and inter-cochlear distance (ICD) was measured in the axial plane at the fundus level between two ears. 3D segmentation of the entire inner ear of both sides and coiled electrode excess lead was performed to visually compare the changes in coiled configuration between the two CT scan time points. RESULT: MT and ICD increased logarithmically with the patient's age, as has been measured from both the 1st and the 2nd CT scans and a weak linear correlation between MT and ICD was observed. Growth in MT and ICT measured between the time of 1st and 2nd CT scans showed a strong linear correlation. In eight cases, changes in the electrode excess lead have been observed in the 2nd CT scan, either a change in the coiling configuration of electrode excess lead or shifted laterally toward the mastoid edge. The ICD growth between the 1st and the 2nd CT scans was >2 mm in only seven cases and all of them were children. All other six cases had no observed changes in the coiled electrode lead. In addition, the mastoid growth between the 1st and the 2nd CT scan was >2.5 mm in only 4 cases. CONCLUSION: Coiled configuration of electrode excess lead could change when the MT and ICD increased over time.

Shape of the Cochlear Basal Turn: An Indicator for an Optimal Electrode-to-Modiolus Proximity With Precurved Electrode Type.

OBJECTIVE: The objective of this study was to determine the shape of cochlear basal turn through basic cochlear parameters measurement. The secondary aim was to overlay an image of the precurved electrode array on top of the three-dimensional (3D) image of the cochlea to determine which shape of the cochlear basal turn gives optimal electrode-to-modiolus proximity. MATERIALS AND METHODS: Computed tomography (CT) preoperative image-data sets of 117 ears were made available for the measurements of cochlear parameters retrospectively. Three-dimensional slicer was used in the visualization and measurement of cochlear parameters from both 3D and 2D (2-dimensional) images of the inner ear. Cochlear parameters including basal turn diameter (A), width of the basal turn (B), and cochlear height (H) were measured from the appropriate planes. B/A ratio was made to investigate which ratios correspond to round and elliptical shape of the cochlear basal turn. RESULTS: The cochlear size as measured by A value ranged between 7.4 mm and 10 mm. The B value and the cochlear height (H) showed a weak positive linear relation with A value. The ratio between the B and A values anything above or below 0.75 could be an indicator for a more round- or elliptical shaped cochlear basal turn, respectively. One sized/shaped commercially available precurved electrode array would not offer a tight electrode-to-modiolus in the cochlea that has an elliptical shaped basal turn as identified by the B/A ratio of <0.75. CONCLUSION: Accurate measurement of cochlear parameters adds value to the overall understanding of the cochlear geometry before a cochlear implantation procedure. The shape of cochlear basal turn could have clinical implications when comes to electrode-to-modiolus proximity.