Preimplant Hearing Threshold: An Important Predictor of Hearing Preservation in Cochlear Implantation With Lateral Wall Electrodes

Hearing Preservation Techniques in Pediatric Cochlear Implantation: A Systematic Review and Meta-Analysis

OBJECTIVE

Preserving residual hearing following cochlear implantation (CI) improves outcomes and allows patients to use electrical and acoustic stimulation. Hearing preservation and minimizing intracochlear trauma during implantation have become key areas of research and device development in recent years. This meta-analysis evaluated whether patient characteristics or surgical methodology impact hearing preservation postpediatric CI.

DATA SOURCES

A systematic search was performed in PubMed, Web of Science, Cochrane Library, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature.

REVIEW METHODS

Per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the databases were searched for English studies published before August 2024. Search terms were "hearing preservation," "cochlear implant," "audiometry," and "pediatric" and their synonyms. The main outcome was the percentage of ears with hearing preservation after CI. Patient, audiological, device, and surgical technique characteristics were extracted. The impact of these factors on hearing preservation was evaluated.

RESULTS

Twenty-four studies were included, with a total of 567 patients. Males comprised 50% of patients (95% confidence interval [CI]: 45%-55%). Mean patient age was 9.68 years (95% CI: 8.27-11.09 years). Mean pure tone averages (PTAs) before and after CI were 60.48 dB (95% CI: 48.81-72.14 dB) and 70.95 dB (95% CI: 56.75-85.15 dB), respectively. Hearing preservation was reported in 78% of ears (95% CI: 71%-85%), with high heterogeneity between studies (I2 = 79.96%). Gender, surgical approach, electrode array, topical corticosteroids, and initial PTA were not significantly associated with hearing preservation.

CONCLUSIONS

Hearing preservation following pediatric CI occurred in 78% of ears. In this meta-analysis, no patient characteristic or surgical technique was significantly associated with hearing preservation.

Scala Tympani Volume Influences Initial 6-Month Hearing Preservation With Lateral Wall Electrode Arrays

OBJECTIVES

To examine the effects of scala tympani (ST) volume, cochlear duct length (CDL), and angular insertion depth (AID) on low-frequency hearing preservation for cochlear implant (CI) recipients of lateral wall electrode arrays.

METHODS

A retrospective review identified 45 adult CI recipients of 24-, 28-, or 31.5-mm lateral wall electrode arrays with preoperative unaided hearing thresholds ≤45 decibel hearing level (dB HL) at 250 Hz. All patients underwent preoperative and postoperative computed tomography to evaluate cochlear morphology and electrode array position. A linear mixed effects model evaluated effects of ST volume, CDL, AID, preoperative low-frequency pure-tone average (LFPTA; 125, 250, and 500 Hz), age at surgery, and biological sex on the postoperative change in LFPTA at activation and 6 months post-activation.

RESULTS

There were significant main effects of ST volume (p = 0.044), age (p = 0.028), and biological sex (p = 0.003), indicating better low-frequency hearing preservation for CI recipients with larger ST volumes, younger age at surgery, and female biological sex. Although CDL positively correlated with ST volume (r = 0.74, p < 0.001), there was no significant main effect of CDL (p = 0.367). A broad range in AID of the most apical electrode contact was observed (301.4°-681.8°); however, there was no significant main effect of AID on low-frequency hearing preservation (p = 0.700).

CONCLUSIONS

During the initial 6 months following implantation, intrinsic factors such as cochlear morphology may have a greater impact on low-frequency hearing preservation than apical positioning of a flexible lateral wall electrode array when using soft surgical techniques.

LEVEL OF EVIDENCE

3 Laryngoscope, 135:1781-1787, 2025.

Outcomes of attempted hearing preservation after cochlear implantation (HPCI): a prognostic factor (PF) systematic review of the literature

OBJECTIVE

There's a need to highlight prognostic factors (PFs) determining hearing preservation in cochlear implantation (HPCI), as currently there is large variability in outcomes. Given the potential benefits of HPCI, it is important to understand the factors influencing this variation. We apply a novel methodology to outline and assess the accuracy of prognostic factors reporting for HPCI.

DATA SOURCES

A preferred reporting item for systematic reviews and meta-analyses compliant systematic review, searches applied to Medline, EMBASE, and Cochrane.

STUDY SELECTION

The CHARMS-PF tool assessed the strength of PF study designs.

DATA EXTRACTION

The QUIPS tool assessed for risk of bias.

DATA SYNTHESIS AND RESULTS

Ninety-two papers were suitable for data extraction. The domain's preoperative hearing loss, size of the round window opening, round window accessibility, surgical insertion speed and route (Round window or cochleostomy), electrode length and type were identifiable exploratory PFs for HPCI. Overall, the study's heterogeneity and risk of bias precluded reporting by forest plots and meta-analysis.

CONCLUSIONS

Most exploratory PF studies for HPCI are hindered by the risk of bias. This systematic review identifies potential independent PFs which should be measured, and adjusted for, in future confirmatory studies using a multivariate analysis. This would determine the independent prognostic effects associated with HPCI while facilitating prognostic model development and the predict individual HPCI.

Predicting Acoustic Hearing Preservation Following Cochlear Implant Surgery Using Machine Learning

OBJECTIVES

The aim of the study was to train and test supervised machine-learning classifiers to predict acoustic hearing preservation after CI using preoperative clinical data.

STUDY DESIGN

Retrospective predictive modeling study of prospectively collected single-institution CI dataset.

METHODS

One hundred and seventy-five patients from a REDCap database including 761 patients >18 years who underwent CI and had audiometric testing preoperatively and one month after surgery were included. The primary outcome variable was the lowest quartile change in acoustic hearing at one month after CI using various formulae (standard pure tone average, SPTA; low-frequency PTA, LFPTA). Analysis involved applying multivariate logistic regression to detect statistical associations and training and testing supervised learning classifiers. Classifier performance was assessed with numerous metrics including area under the receiver operating characteristic curve (AUC) and Matthews correlation coefficient (MCC).

RESULTS

Lowest quartile change (indicating hearing preservation) in SPTA was positively associated with a history of meningitis, preoperative LFPTA, and preoperative SPTA. Lowest quartile change in SPTA was negatively associated with sudden hearing loss, noise exposure, aural fullness, and abnormal anatomy. Lowest quartile change in LFPTA was positively associated with preoperative LFPTA. Lowest quartile change in LFPTA was negatively associated with tobacco use. Random forest demonstrated the highest mean classification performance on the validation dataset when predicting each of the outcome variables.

CONCLUSIONS

Machine learning demonstrated utility for predicting preservation of residual acoustic hearing in patients undergoing CI surgery, and the detected associations facilitated the interpretation of our machine-learning models. The models and statistical associations together may be used to facilitate improvements in shared clinical decision-making and patient outcomes.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:926-936, 2024.

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

OBJECTIVE

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.

STUDY DESIGN

Retrospective cohort study.

SETTING

Large academic cochlear implant referral center.

METHODS

We reviewed adult HP CI cases using either the slim modiolar electrode (SME) (CI 532/CI 632) or th slim lateral wall electrode (SLWE) (CI 624). One-year speech outcomes and HP status were the primary outcomes.

RESULTS

A total of 132 implanted ears were analyzed (mean age 73.1 years, standard deviation [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 (66.9 vs 80.3 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.

CONCLUSION

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.

National study of hearing preservation rates and outcomes after cochlear implantation in Ireland

OBJECTIVE

To study the rate of hearing preservation and outcomes of hearing preservation candidates in a national cochlear implant centre. The HEARRING criteria was used.

METHODS

All cochlear implant candidates with preserved low frequency pure tone average (PTA) were included. All patients underwent cochlear implantation using a standard 'soft-surgery' technique. PTA was assessed at switch-on, 3, 6, 9 and 12 months postoperatively. The primary outcome was hearing preservation at 12 months.

RESULTS

Sixty six patients were included in the study between 2015 and 2020. Seventy one ears were implanted including 33 adults and 33 children with 5 bilateral implantations. Mean preoperative PTA was 74.8 dB (range 52.3-92 dB), mean postoperative PTA was 95.3 dB corresponding to a mean shift of 20.5 dB. In the adult population, HP rates were as follows: complete HP in 13%, partial HP in 39.1%, minimal HP in 30.4%, loss of hearing in 17.4%. In the paediatric population: complete HP in 20.7%, partial HP in 51.7%, minimal HP in 13.8% and loss of hearing in 13.8%. After the initial postoperative shift, there was no significant worsening of residual hearing during follow-up between 3 and 12 months. There were no significant prognostic factors for hearing preservation.

CONCLUSION

Hearing preservation rates using the HEARRING criteria are described. This study will help counselling and decision making in patients eligible for cochlear implantation with hearing preservation. Further studies are required to assess the performances and outcomes of electronatural and electroacoustic stimulation.

Pneumolabyrinth as an Early Computed Tomographic Finding After Cochlear Implantation and its Clinical Significance

OBJECTIVE

To determine the incidence and volume of pneumolabyrinth using early temporal bone computed tomography (TBCT) findings and evaluate the correlation between pneumolabyrinth and various clinical variables.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary academic center.

PATIENTS

Fifty-three consecutive adult cochlear implantation (CI) recipients (53 ears) with normal inner ears who underwent high-resolution TBCT within 3 days after CI were included.

INTERVENTION

Axial TBCT images were used for detection and measurement of pneumolabyrinth.

MAIN OUTCOME MEASURES

Incidence and volume of pneumolabyrinth were evaluated. In addition, the following clinical variables were analyzed to evaluate the correlation with pneumolabyrinth volume: demographics, implant type, surgical approach, postoperative dizziness, and preservation of functional residual hearing.

RESULTS

Pneumolabyrinth was present in all patients, and the average volume was 8.496 mm3. Pneumolabyrinth was confined to the cochlea (pneumocochlea) in all patients except for one who also had pneumovestibule. The pneumolabyrinth volume in patients with postoperative dizziness was significantly larger than that in patients without postoperative dizziness (10.435 mm3 vs. 8.016 mm3; p = 0.029). Multivariate analysis showed that a larger volume of pneumolabyrinth was significantly associated with postoperative dizziness (odds ratio, 1.420; 95% confidence interval, 1.114-1.808; p = 0.005).

CONCLUSION

A certain volume of pneumolabyrinth was always present in the early stage after CI, and the volume of pneumolabyrinth measured using early TBCT findings was significantly associated with the occurrence of postoperative dizziness.

One Year Assessment of the Hearing Preservation Potential of the EVO Electrode Array

Background: A prospective longitudinal multicentre study was conducted to assess the one-year postsurgical hearing preservation profile of the EVO^TM electrode array. Methods: Fifteen adults presenting indications of electro-acoustic stimulation (pure-tone audiometry (PTA) thresholds ≤70 dB below 750 Hz) were implanted with the EVO™ electrode array. Hearing thresholds were collected at five time-points from CI activation to twelve months (12M) after activation. Hearing thresholds and hearing preservation profiles (HEARRING group classification) were assessed. Results: All subjects had measurable hearing thresholds at follow-up. No case of complete loss of hearing or minimal hearing preservation was reported at any time point. At activation (N_act = 15), five participants had complete hearing preservation, and ten participants had partial hearing preservation. At the 12M time point (N_12m = 6), three participants had complete hearing preservation, and three participants had partial hearing preservation. Mean hearing loss at activation was 11 dB for full range PTA and 25 dB for PTAs low-frequency (125–500 Hz). Conclusions: This study provides the first longitudinal follow-up on associated hearing profiles to the EVO™ electrode array, which are comparable to the literature. However, other studies on larger populations should be performed.