Survey of the American Neurotology Society on Cochlear Implantation: Part 2, Surgical and Device-Related Practice Patterns

Minimum intraoperative testing battery for cochlear implantation: the international practice trend

PURPOSE

In cochlear implantation (CI) surgery, there are a wide variety of intraoperative tests available. However, no clear guide exists on which tests must be performed as the minimum intraoperative testing battery. Toward this end, we studied the usage patterns, recommendations, and attitudes of practitioners toward intraoperative testing.

METHODS

This study is a multicentric international survey of tertiary referral CI centers. A survey was developed and administered to a group of CI practitioners (n = 34) including otologists, audiologists and biomedical engineers. Thirty six participants were invited to participate in this study based on a their scientific outputs to the literature on the intraoperative testing in CI field and based on their high load of CI surgeries. Thirty four, from 15 countries have accepted the invitation to participate. The participants were asked to indicate the usage trends, perceived value, influence on decision making and duration of each intraoperative test. They were also asked to indicate which tests they believe should be included in a minimum test battery for routine cases.

RESULTS

Thirty-two (94%) experts provided responses. The most frequently recommended tests for a minimum battery were facial nerve monitoring, electrode impedance measurements, and measurements of electrically evoked compound action potentials (ECAPs). The perceived value and influence on surgical decision-making also varied, with high-resolution CT being rated the highest on both measures.

CONCLUSION

Facial nerve monitoring, electrode impedance measurements, and ECAP measurements are currently the core tests of the intraoperative test battery for CI surgery.

Patient Preferences in Cochlear Implant Manufacturer Selection

OBJECTIVE

To assess the factors that drive a patient's selection of cochlear implant (CI) manufacturer.

STUDY DESIGN

Prospective survey study.

SETTING

Tertiary referral center.

PATIENTS

One hundred twenty-eight adult patients undergoing primary CI.

INTERVENTIONS

Survey administered in the preoperative area.

MAIN OUTCOME MEASURES

Sources of information regarding CI manufacturer offerings, factors that were most important in deciding on a manufacturer, and manufacturer ultimately selected.

RESULTS

One hundred twenty-eight patients were included (average age, 63.7 years; 97% White). The most cited source of information that patients used to choose a device was his/her audiologist (80.5% of patients). When asked his/her number 1 reason for choosing their CI manufacturer, the most commonly cited reason was technology (e.g., battery life, device pairing), regardless of manufacturer. When asked about specific technology offerings, hearing aid pairing was rated as the most important. The numbers 2 and 3 reasons for choosing a manufacturer were cosmetics/structure of the wearable portion of the device and audiologist recommendation of that manufacturer, respectively. The relative weight given to each of the top 3 reasons differed significantly across the three manufacturers ( p = 0.017).

CONCLUSIONS

Audiologists are by far the leading source of information used by patients choosing a CI manufacturer. Patients prioritize technology most when choosing an implant manufacturer, but audiologist recommendation and the cosmetics and structure of the wearable device are also important. CI manufacturers should be mindful of patient priorities when designing and marketing their devices.

Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates

OBJECTIVES

Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation.

METHODS

Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA.

RESULTS

Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing.

DISCUSSION

There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs.

CONCLUSION

Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.

Cochlear implant positioning: development and validation of an automatic method using computed tomography image analysis

The aim of this study was to preoperatively asses the feasibility of drilling a bony recess for the fixation of a cochlear implant in the temporal bone. Even though complications are rare with cochlear implantations, drilling at the site of implantation have resulted in hematoma or cerebrospinal fluid leakage. Mainly in cases with a reduced temporal bone thickness, the risk for complications has increased, such as in paediatric patients.

Methods

An in-house designed semi-automatic algorithm was developed to analyse a 3D model of the skull. The feasibility of drilling the recess was determined by a gradient descent method to search for the thickest part of the temporal bone. Feasibility was determined by the residual bone thickness which was calculated after a simulated drilling of the recess at the thickest position. An initial validation of the algorithm was performed by measuring the accuracy of the algorithm on five 3D models with known thickest locations for the recess. The accuracy was determined by a part comparison between the known position and algorithm provided position.

Results

In four of the five validation models a standard deviation for accuracy below the predetermined cut-off value of 4.2 mm was achieved between the actual thickest position and the position determined by the algorithm. Furthermore, the residual thickness calculated by the algorithm showed a high agreement (max. 0.02 mm difference) with the actual thickness.

Conclusion

With the developed algorithm, a semi-automatic method was created to analyse the temporal bone thickness within a specified region of interest on the skull. Thereby, providing indications for surgical feasibility, potential risks for anatomical structures and impact on procedure time of cochlear implantation. This method could be a valuable research tool to objectively assess feasibility of drilling a recess in patients with thin temporal bones preoperatively.

Age and Incidence of Cochlear Implantation in the Pediatric Population With Congenital Bilateral Profound Hearing Loss

OBJECTIVES

The current study characterizes age and incidence of cochlear implantation among qualifying children with congenital bilateral profound hearing loss in the U.S.

STUDY DESIGN

Deidentified cochlear implantation data were acquired from prospectively collected patient registries from two cochlear implant (CI) manufacturers (Cochlear Americas and Advanced Bionics). Children <36 months old were assumed to have congenital bilateral profound sensorineural hearing loss.

SETTING

U.S. CI centers.

PATIENTS

Children <36 months old who received CIs.

INTERVENTIONS

Cochlear implantation.

MAIN OUTCOME MEASURES

Age at implantation and incidence.

RESULTS

A total of 4,236 children <36 months old underwent cochlear implantation from 2015 to 2019. The median age at implantation was 16 months (interquartile range, 12-24 mo) and did not change significantly during the 5-year study period (p = 0.09). Patients residing closer to CI centers (p = 0.03) and treated at higher-volume centers (p = 0.008) underwent implantation at a younger age. Bilateral simultaneous implantation increased from 38% to 53% of CI surgeries in 2015 and 2019, respectively. Children who received bilateral simultaneous CIs were younger compared with those receiving unilateral or bilateral sequential CIs (median, 14 versus 18 mo; p < 0.001). The incidence of cochlear implantation increased from 7,648 per 100,000 person-years in 2015 to 9,344 in 2019 (p < 0.001).

CONCLUSION

Although the incidence of pediatric CI recipients and the frequency of bilateral simultaneous implantation increased over the study period, age at implantation did not change significantly and far exceeded current Food and Drug Administration (9 mo) and American Academy of Otolaryngology and Head and Neck Surgery position statement (6-12 mo) guidelines.

Impact of Scala Tympani Geometry on Insertion Forces during Implantation

(1) Background: During a cochlear implant insertion, the mechanical trauma can cause residual hearing loss in up to half of implantations. The forces on the cochlea during the insertion can lead to this mechanical trauma but can be highly variable between subjects which is thought to be due to differing anatomy, namely of the scala tympani. This study presents a systematic investigation of the influence of different geometrical parameters of the scala tympani on the cochlear implant insertion force. The influence of these parameters on the insertion forces were determined by testing the forces within 3D-printed, optically transparent models of the scala tympani with geometric alterations. (2) Methods: Three-dimensional segmentations of the cochlea were characterised using a custom MATLAB script which parametrised the scala tympani model, procedurally altered the key shape parameters (e.g., the volume, vertical trajectory, curvature, and cross-sectional area), and generated 3D printable models that were printed using a digital light processing 3D printer. The printed models were then attached to a custom insertion setup that measured the insertion forces on the cochlear implant and the scala tympani model during a controlled robotic insertion. (3) Results: It was determined that the insertion force is largely unaffected by the overall size, curvature, vertical trajectory, and cross-sectional area once the forces were normalised to an angular insertion depth. A Capstan-based model of the CI insertion forces was developed and matched well to the data acquired. (4) Conclusion: By using accurate 3D-printed models of the scala tympani with geometrical alterations, it was possible to demonstrate the insensitivity of the insertion forces to the size and shape of the scala tympani, after controlling for the angular insertion depth. This supports the Capstan model of the cochlear implant insertion force which predicts an exponential growth of the frictional force with an angular insertion depth. This concludes that the angular insertion depth, rather than the length of the CI inserted, should be the major consideration when evaluating the insertion force and associated mechanical trauma caused by cochlear implant insertion.

Current Estimates of Cochlear Implant Utilization in the United States

OBJECTIVE

To present key data from a private marketing report that characterizes U.S. cochlear implant (CI) utilization, potential CI candidate and recipient population sizes, and CI market growth.

PATIENTS

Individuals who may benefit from CI and CI recipients in the United States.

INTERVENTIONS

Cochlear implantation.

MAIN OUTCOME MEASURES

CI utilization, potential CI candidate and recipient population sizes, and CI market size and value.

RESULTS

As of 2015, a cumulative 170,252 people (240,056 devices) had undergone cochlear implantation in the United States. In the year 2015, approximately 30% of devices were implanted in bilateral CI patients, through simultaneous or sequential implantation. When considering traditional audiometric CI candidacy criteria (patients with severe to profound sensorineural hearing loss in the better hearing ear), utilization rates among the population who may benefit from CI approximated 12.7%. When considering expanded criteria including individuals with single-sided deafness or asymmetrical hearing loss (severe to profound hearing loss in the worse hearing ear), utilization rates approximated 2.1%. In 2015, there was a net increase of 20,093 individuals who may have benefited from CI who had not undergone CI, adding to the group of about 1.3 M untreated audiometric CI candidates who existed prior to that year. The CI market was valued at $450.8 M in 2015, with an average device selling price of $25,701 per device.

CONCLUSIONS

CI utilization rates remain low among individuals who meet audiometric criteria for CI. Although the annual proportion of CI recipients to new audiometric candidates has increased, the total population of untreated audiometric CI candidates continues to rise.

Conversations in Cochlear Implantation: The Inner Ear Therapy of Today

As biomolecular approaches for hearing restoration in profound sensorineural hearing loss evolve, they will be applied in conjunction with or instead of cochlear implants. An understanding of the current state-of-the-art of this technology, including its advantages, disadvantages, and its potential for delivering and interacting with biomolecular hearing restoration approaches, is helpful for designing modern hearing-restoration strategies. Cochlear implants (CI) have evolved over the last four decades to restore hearing more effectively, in more people, with diverse indications. This evolution has been driven by advances in technology, surgery, and healthcare delivery. Here, we offer a practical treatise on the state of cochlear implantation directed towards developing the next generation of inner ear therapeutics. We aim to capture and distill conversations ongoing in CI research, development, and clinical management. In this review, we discuss successes and physiological constraints of hearing with an implant, common surgical approaches and electrode arrays, new indications and outcome measures for implantation, and barriers to CI utilization. Additionally, we compare cochlear implantation with biomolecular and pharmacological approaches, consider strategies to combine these approaches, and identify unmet medical needs with cochlear implants. The strengths and weaknesses of modern implantation highlighted here can mark opportunities for continued progress or improvement in the design and delivery of the next generation of inner ear therapeutics.

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.

The Limitations of FDA Criteria: Inconsistencies with Clinical Practice, Findings, and Adult Criteria as a Barrier to Pediatric Implantation

Children require greater access to sound than adults as they are learning to communicate using hearing and spoken language. Yet when it comes to cochlear implant candidacy, currently approved Food and Drug Administration (FDA) criteria for adults are much less restrictive than those for children, allowing for greater levels of residual hearing and aided speech recognition in adults. Cochlear implant guidelines for children have changed very little in the 30 years since cochlear implants have been approved for pediatrics, and this lack of change has proven to be a barrier to implantation. Using evidence-based practice, centers have been providing off-label implantation for children who fall outside of current FDA criteria, including children with more residual hearing, children with single-side deafness younger than 5 years, and infants with bilateral profound loss younger than 9 months. The purpose of this article is to outline how these restrictions impede access to implants for children and describe the evidence supporting cochlear implantation in children who fall outside of current criteria.

Robotic Milling of Electrode Lead Channels During Cochlear Implantation in an ex-vivo Model

Objective: Robotic cochlear implantation is an emerging surgical technique for patients with sensorineural hearing loss. Access to the middle and inner ear is provided through a small-diameter hole created by a robotic drilling process without a mastoidectomy. Using the same image-guided robotic system, we propose an electrode lead management technique using robotic milling that replaces the standard process of stowing excess electrode lead in the mastoidectomy cavity. Before accessing the middle ear, an electrode channel is milled robotically based on intraoperative planning. The goal is to further standardize cochlear implantation, minimize the risk of iatrogenic intracochlear damage, and to create optimal conditions for a long implant life through protection from external trauma and immobilization in a slight press fit to prevent mechanical fatigue and electrode migrations.

Methods: The proposed workflow was executed on 12 ex-vivo temporal bones and evaluated for safety and efficacy. For safety, the difference between planned and resulting channels were measured postoperatively in micro-computed tomography, and the length outside the planned safety margin of 1.0 mm was determined. For efficacy, the channel width and depth were measured to assess the press fit immobilization and the protection from external trauma, respectively.

Results: All 12 cases were completed with successful electrode fixations after cochlear insertions. The milled channels stayed within the planned safety margins and the probability of their violation was lower than one in 10,000 patients. Maximal deviations in lateral and depth directions of 0.35 and 0.29 mm were measured, respectively. The channels could be milled with a width that immobilized the electrode leads. The average channel depth was 2.20 mm, while the planned channel depth was 2.30 mm. The shallowest channel depth was 1.82 mm, still deep enough to contain the full 1.30 mm diameter of the electrode used for the experiments.

Conclusion: This study proposes a robotic electrode lead management and fixation technique and verified its safety and efficacy in an ex-vivo study. The method of image-guided robotic bone removal presented here with average errors of 0.2 mm and maximal errors below 0.5 mm could be used for a variety of other otologic surgical procedures.

Barriers to Adult Cochlear Implant Care in the United States: An Analysis of Health Care Delivery

Persistent underutilization of cochlear implants (CIs) in the United States is in part a reflection of a lack of hearing health knowledge and the complexities of care delivery in the treatment of sensorineural hearing loss. An evaluation of the patient experience through the CI health care delivery process systematically exposes barriers that must be overcome to undergo treatment for moderate-to-severe hearing loss. This review analyzes patient-facing obstacles including diagnosis of hearing loss, CI candidate identification and referral to surgeon, CI evaluation and candidacy criteria interpretation, and lastly CI surgery and rehabilitation. Pervasive throughout the process are several themes which demand attention in addressing inequities in hearing health disparities in the United States.

Hydraulic insertions of cochlear implant electrode arrays into the human cadaver cochlea: preliminary findings

OBJECTIVES

(1) To evaluate the feasibility of a non-invasive, novel, simple insertion tool to perform automated, slow insertions of cochlear implant electrode arrays (EA) into a human cadaver cochlea; (2) to estimate the handling time required by our tool.

METHODS

Basic science study conducted in an experimental OR. Two previously anonymized human cadaver heads, three commercially available EAs, and our novel insertion tool were used for the experiments. Our tool operates as a hydraulic actuator that delivers an EA at continuous velocities slower than manually feasible.

INTERVENTION(S)

the human cadaver heads were prepared with a round-window approach for CI surgery in a standard fashion. Twelve EA insertion trials using our tool involved: non-invasive fixation of the tool to the head; directing the tool to the round window and EA mounting onto the tool; automated EA insertion at approximately 0.1 mm/s driven by hydraulic actuation. Outcome measurement(s): handling time of the tool; post-insertion cone-beam CT scans to provide intracochlear evaluation of the EA insertions.

RESULTS

Our insertion tool successfully inserted an EA into the human cadaver cochlea (n = 12) while being attached to the human cadaver head in a non-invasive fashion. Median time to set up the tool was 8.8 (7.2-9.4) min.

CONCLUSION

The first insertions into the human cochlea using our novel, simple insertion tool were successful without the need for invasive fixation. The tool requires < 10 min to set up, which is clinically acceptable. Future assessment of intracochlear trauma is needed to support its safety profile for clinical translation.

The Effect of Ultra-slow Velocities on Insertion Forces: A Study Using a Highly Flexible Straight Electrode Array

OBJECTIVE

The present study sought to 1) characterize insertion forces resulting from a flexible straight electrode array (EA) inserted at slow and ultra-slow insertion velocities, and 2) evaluate if ultra-slow velocities decrease insertion forces independent of other variables.

BACKGROUND

Low insertion forces are desirable in cochlear implant (CI) surgery to reduce trauma and preserve hearing. Recently, ultra-slow insertion velocities (lower than manually feasible) have been shown to produce significantly lower insertion forces using other EAs.

METHODS

Five flexible straight EAs were used to record insertion forces into an inelastic artificial scala tympani model. Eleven trial recordings were performed for each EA at five predetermined automated, continuous insertion velocities ranging from 0.03 to 1.6 mm/s.

RESULTS

An ultra-slow insertion velocity of 0.03 mm/s resulted in a median insertion force of 0.010 N at 20 mm of insertion depth, and 0.026 N at 24.3 mm-the final insertion depth. These forces represent only 24 to 29% of those measured using 1.6 mm/s. After controlling for insertion depth of the EA into the artificial scala tympani model and trial insertion number, decreasing the insertion velocity from 0.4 to 0.03 mm/s resulted in a 50% decrease in the insertion forces.

CONCLUSION

Using the tested EA ultra-slow velocities can decrease insertion forces, independent of variables like insertion depth. Our results suggest ultra-slow velocities can reduce insertion forces at least 60%, compared with humanly feasible continuous velocities (≥0.9 mm/s).

Clinical characteristics and outcomes of children with cochlear implants who had preoperative residual hearing

OBJECTIVE

Cochlear implants (CI) candidacy criteria have expanded to include children with more residual hearing. This study explored the clinical profiles and outcomes of children with CIs who had preoperative residual hearing in at least one ear.

DESIGN

A retrospective chart review was conducted to collect clinical characteristics and speech perception data. Pre- and post-CI auditory and speech perception data were analysed using a modified version of the Pediatric Ranked Order Speech Perception (PROSPER) score.

STUDY SAMPLE

This study included all children with residual hearing who received CIs in one Canadian paediatric centre from 1992 to 2018.

RESULTS

A total of 100 of 389 (25.7%) children with CIs had residual hearing (median 77.6 dB HL, better ear). The proportion of children with residual hearing increased from 1992 to 2018. Children who had auditory behaviour and speech perception tests (n = 83) showed higher modified PROSPER scores post-CI compared to pre-CI. Phonologically Balanced Kindergarten (PBK) test scores were available for 71 children post-CI; 81.7% (58/71) of children achieved > 80% on the PBK.

CONCLUSIONS

One in four children who received CIs had residual hearing, and most of them had severe hearing loss at pre-CI. These children showed a high level of speech perception with CIs.

Cochlear Implantation and Electric Acoustic Stimulation in Children With TMPRSS3 Genetic Mutation

BACKGROUND

Mutations in the TMPRSS3 gene, although rare, can cause high frequency hearing loss with residual hearing at low frequencies. Several previous studies have reported cochlear implant (CI) outcomes for adults with TMPRSS3 mutation with mixed results. Although some studies have suggested that TMPRSS3 is expressed in spiral ganglion cells, it remains unclear if previously reported poor CI outcomes in this population were secondary to long durations of deafness or to the effects of the TMPRSS3 mutation. To date, no studies in the literature have reported CI outcomes for children with TMPRSS3 mutation treated with CI.

OBJECTIVE

The current case series aimed to describe outcomes for three children with sloping hearing loss caused by TMPRSS3 mutation who underwent bilateral CI.

STUDY DESIGN

Case series.

SETTING

Academic medical center.

PATIENTS

Three children (3-4 yr) with TMPRSS3 mutation and normal sloping to profound high frequency hearing loss.

INTERVENTIONS

CI and electric acoustic stimulation (EAS).

MAIN OUTCOME MEASURES

Outcome measures were residual hearing thresholds, speech recognition scores, and electrode placement determined via intraoperative CT imaging.

RESULTS

All three children maintained residual acoustic hearing and received benefit from EAS. Mean change in low-frequency pure-tone average was 17 dB. Mean postoperative word and sentence recognition scores in the bilateral EAS condition were 80 and 75%, respectively.

CONCLUSIONS

Results indicate that CI with EAS is an appropriate treatment for children with TMPRSS3 genetic mutation. Pediatric results from this case series show more favorable CI outcomes than are currently reported for adults with TMPRSS3 mutation suggesting that the intervention may be time sensitive.

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

OBJECTIVE

To evaluate the outcomes and association factors of long-term hearing preservation (HP) in cochlear implantation with lateral wall (LW) electrode arrays.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary academic center.

PATIENTS

Thirty-four consecutive ears from 32 patients with a ≤ 80 dB HL preoperative low-frequency pure-tone average of 250 to 500 Hz were included.

INTERVENTION

Cochlear implantation with LW electrode arrays and the intention of achieving HP.

MAIN OUTCOME MEASURES

HP classifications according to the HEARRING group and functional HP methods (≤ 85 dB HL of pure-tone threshold at 250 Hz) at 1 year postoperatively.

RESULTS

Based on the HEARRING classification, complete, partial, and minimal HP was achieved in 7 ears (21%), 12 ears (35%), and 4 ears (12%), respectively. Under functional classification, 14 ears (41%) exhibited functional hearing after surgery. The average threshold shift was 17.1 dB HL (SD = 16.9 dB HL). Among various clinical features, a ≤ 60 dB HL preimplant pure-tone threshold of 250 Hz was associated with HP outcome in both classifications (OR = 12.95, 95% CI = 1.29-130.01, p = 0.029 in HEARRING classification; OR = 14.36, 95% CI = 1.07-191.40, p = 0.044 in functional classification). The following parameters were not associated with HP (p > 0.05): patient demographics, surgical aspects (insertion route and depth), electrode array size, scalar electrode position, and presence of comorbidity.

CONCLUSION

With LW electrode arrays, HP was achieved in 68% of HEARRRING group patients and 41% of functional classification patients. A ≤ 60 dB HL preimplant pure-tone threshold of 250 Hz was significantly associated with an increased rate of long-term HP.

Osseointegration Pharmacology: A Systematic Mapping Using Artificial Intelligence

Clinical performance of osseointegrated implants could be compromised by the medications taken by patients. The effect of a specific medication on osseointegration can be easily investigated using traditional systematic reviews. However, assessment of all known medications requires the use of evidence mapping methods. These methods allow assessment of complex questions, but they are very resource intensive when done manually. The objective of this study was to develop a machine learning algorithm to automatically map the literature assessing the effect of medications on osseointegration. Datasets of articles classified manually were used to train a machine-learning algorithm based on Support Vector Machines. The algorithm was then validated and used to screen 599,604 articles identified with an extremely sensitive search strategy. The algorithm included 281 relevant articles that described the effect of 31 different drugs on osseointegration. This approach achieved an accuracy of 95%, and compared to manual screening, it reduced the workload by 93%. The systematic mapping revealed that the treatment outcomes of osseointegrated medical devices could be influenced by drugs affecting homeostasis, inflammation, cell proliferation and bone remodeling. The effect of all known medications on the performance of osseointegrated medical devices can be assessed using evidence mappings executed with highly accurate machine learning algorithms.

Cochlear implants in Japan: Results of cochlear implant reporting system over more than 30 years

OBJECTIVE

To conduct a longitudinal national survey of cochlear implantation (CI) in Japan from 1985 through 2017.

METHODS

A retrospective analysis of adult and pediatric CI cases from 1985 to 2017 using the Oto-Rhino-Laryngological Society of Japan CI registration database was conducted. Surgical statistics were obtained, including number of surgeries, age, implanted side, facilities, and preoperative threshold levels for CI.

RESULTS

Since 1985, more than 11,100 CI surgeries have been conducted in Japan. The number exceeded 500 in 2005 and 1,000 in 2015. Since 2007, pediatric cases consistently surpassed adult cases until 2016. More facilities meet criteria for conducting CI as determined by Ministry of Health, Labor and Welfare and have now reached more than 100. Adult patients over 70 years old have become proportionally higher. Age at implantation steadily reduced in accordance with modifications of Japanese CI guidelines for children but is still not comparable to that in other developed countries. Although the number of CI surgeries for patients with moderate to severe hearing loss increased in the past ten years, the proportion was small.

CONCLUSIONS

The CI database in Japan is quite unique in that it documents almost all the CI surgeries in Japan, allowing us to summarize the present situation as follows: fewer CI surgeries occur than are necessary, and children receiving implants are older than those in other developed countries. Continuous improvement of CI awareness is needed in Japan.

Operative Technique and Workflow of Deep Brain Stimulation Surgery With Pre-existing Cochlear Implants

BACKGROUND

Deep brain stimulation (DBS) surgery in patients with pre-existing cochlear implants (CIs) poses various challenges. We previously reported successful magnetic resonance imaging (MRI)-based, microelectrode recording (MER)-guided subthalamic DBS surgery in a patient with a pre-existing CI. Other case reports have described various DBS procedures in patients with pre-existing CIs using different techniques, leading to varying issues to address. A standardized operative technique and workflow for DBS surgery in the setting of pre-existing CIs is much needed.

OBJECTIVE

To provide a standardized operative technique and workflow for DBS lead placement in the setting of pre-existing CIs.

METHODS

Our operative technique is MRI-based and MER-guided, following a workflow involving coordination with a neurotology team to remove and re-implant the internal magnets of the CIs in order to safely perform DBS lead placement, altogether within a 24-h time frame. Intraoperative nonverbal communication with the patient is easily possible using a computer monitor.

RESULTS

A 65-yr old woman with a 10-yr history of craniocervical dystonia and pre-existing bilateral CIs underwent successful bilateral pallidal DBS surgery at our institution. No merging errors or difficulties in targeting globus pallidus internus were experienced. Also, inactivated CIs do not interfere with MER nor with stimulation, and intraoperative communication with the patient using a computer monitor proved feasible and satisfactory.

CONCLUSION

DBS procedures are safe and feasible in patients with pre-existing CIs if precautions are taken following our workflow.

Cochlear Implant Receiver Location and Migration: Experimental Validation Pilot Study of a Clinically Applicable Screening Method

Objectives: Postoperative follow-up after cochlear implantation lacks a reliable screening method to detect cochlear implant receiver device migration. This study aims to validate a clinically applicable method to assess the position and migration of the cochlear implant receiver device.

Study design: Validation study.

Setting: Tertiary university medical center.

Participants and method: To assess the cochlear implant receiver device location, round markers representing the external magnet were placed on both sides of the head of volunteers. Four independent clinicians took measurements of the distances between reference points on the head and the center of the marker. The reference points were: the lateral canthus (LC), tragus tip (TT), the mastoid angle (MA), and the mandibular angle (AM).

Main outcome measures: The inter-clinician reliability was determined by calculating the intraclass correlation coefficient (ICC) and confidence interval (CI) with a two-way mixed model and both consistency and absolute agreement types for each distance.

Results: Eight volunteers were included resulting in 16 individual cases. The consistency type ICC's for each reference point were: LC 0.90 (CI = 0.80, 0.96), TT 0.83 (CI = 0.69, 0.93), MA 0.75 (CI = 0.56, 0.89), and AM 0.29 (CI = 0.05, 0.59). The absolute agreement ICC's were: LC 0.87 (CI = 0.73, 0.95), TT 0.83 (CI = 0.68, 0.93), MA 0.68 (CI = 0.42, 0.86), and AM 0.18 (CI = 0.01, 0.46). The inter-clinician reliability was good to excellent for the lateral canthus and tragus tip reference points.

Conclusions: The cochlear receiver device location can be assessed reliably by measuring the distance between the LC, TT, and the external magnet. This method can be used to registrate implant receiver location after implantation and detect implant migration postoperatively.

The Forgotten Second Window: A Pictorial Review of Round Window Pathologies

The round window serves to decompress acoustic energy that enters the cochlea via stapes movement against the oval window. Any inward motion of the oval window via stapes vibration leads to outward motion of the round window. Occlusion of the round window is a cause of conductive hearing loss because it increases the resistance to sound energy and consequently dampens energy propagation. Because the round window niche is not adequately evaluated by otoscopy and may be incompletely exposed during an operation, otologic surgeons may not always correctly identify associated pathology. Thus, radiologists play an essential role in the identification and classification of diseases affecting the round window. The purpose of this review is to highlight the developmental, acquired, neoplastic, and iatrogenic range of pathologies that can be encountered in round window dysfunction.

Speech Recognition in Noise for Adults With Normal Hearing: Age-Normative Performance for AzBio, BKB-SIN, and QuickSIN

OBJECTIVE

Characterize performance for adults aged 20 to 79 years with normal hearing on tasks of AzBio, Bamford-Kowal-Bench speech-in-noise (BKB-SIN), quick speech-in-noise (QuickSIN), and acoustic Quick Spectral Modulation Detection (QSMD) in the sound field.

SETTING

Cochlear implant (CI) program.

PATIENTS

Eighty-one adults with normal hearing and cognitive function were recruited evenly across four age groups (20-49, 50-59, 60-69, and 70-79 yr).

INTERVENTIONS

Subjects completed AzBio sentence recognition testing in quiet and in five signal-to-noise ratios (SNRs: +10, +5, 0, -5, -10 dB), as well as the BKB-SIN, QuickSIN, and QSMD tasks.

MAIN OUTCOME MEASURES

AzBio, BKB-SIN, QuickSIN, and acoustic QSMD scores were analyzed to characterize typical sound field performance in an older adult population with normal hearing.

RESULTS

AzBio sentence recognition performance approached ceiling for sentences presented at ≥ 0 dB SNR with mean scores ranging from 3.5% at -10 dB SNR to 99% at +10 dB SNR. Mean QuickSIN SNR-50 was -0.02. Mean BKB-SIN SNR-50 was -1.31 dB. Mean acoustic QSMD score was 88%. Performance for all measures decreased with age.

CONCLUSION

Adults with age-normative hearing achieve ceiling-level performance for AzBio sentence recognition at SNRs used for clinical cochlear implant and/or hearing aid testing. Thus, these tasks are not inherently contraindicated for older listeners. Older adults with normal hearing, however, demonstrated greater deficits for speech in noise compared to younger listeners-an effect most pronounced at negative SNRs. Lastly, BKB-SIN data obtained in the sound field replicated previous normative data for only the youngest age group, suggesting that new norms should be considered for older populations.

Considerations and Rationale for Cochlear Implant Electrode Design - Past, Present and Future

The electrode array of a cochlear implant forms a permanent, often lifelong interface between the implanted electronics and neural structures of the cochlea. A cochlear implant is primarily prescribed to restore hearing via electrical stimulation of the auditory nerve. As with any neural stimulator intended to either deliver electrical stimulus or record a neural response, the aim is to place the electrodes in close proximity to the target neural structures. The broadening of indications and the concept of preservation of low-frequency residual hearing over the last two decades has resulted in an increased understanding of the mechanisms and implications of intracochlear trauma for both the hearing preservation surgery and electrical stimulation outcomes with cochlear implantation, as well as the influence of many biographic and audiological patient factors correlated with achieving better hearing outcomes. These two goals, the proximity to the cochlear nerve for electrical stimulation and the preservation of cochlear structures, have typically been viewed as mutually exclusive, with perimodiolar electrode arrays being preferred for the former, and lateral wall electrode arrays for the latter. The design evolution of both the lateral wall and perimodiolar electrodes is presented, considering the cochlea anatomy and continued understanding of the mechanics and dynamics of electrode insertion, along with the influence of the ongoing changes to the intracochlear environment to provide a rationale for the electrode design with the intent to provide the greatest patient benefit over their implanted lifetime.