Evaluating Reasons for Revision Surgery and Device Failure Rates in Patients Who Underwent Cochlear Implantation Surgery

Implantation and reimplantation: epidemiology, etiology and pathogenesis over the last 30 years

INTRODUCTION

Due to the increasing number of cochlear implant (CI) recipients, growing indications, and the aging population, the reimplantation of CI recipients has become a focus of attention. The aim of this study is to examine the causes, timing, and postoperative speech understanding in a large cohort over the past 30 years.

METHODS

A retrospective data analysis was conducted on over 4000 CI recipients and 214 reimplanted children and adults from 1993 to 2020. This involved collecting and comparing data on causes, manufacturer information, and demographic data. In addition, a comparison of speech understanding in Freiburg monosyllables and numbers before and after reimplantation was carried out.

RESULTS

Children did not exhibit elevated rates of reimplantation. The overall reimplantation rate in the entire cohort was 5%. The CI overall survival rate after 10 years in the entire cohort was 95.2%. Device failure was the most common reason for reimplantation, with 48% occurring within the first 5 years after implantation. The second most common reason was medical complications, with the risk of reimplantation decreasing as more time passed since the initial implantation. There were no significant differences in Freiburg numbers and monosyllable comprehension before and after reimplantation, both in the overall cohort and in the subcohorts based on indications. Even a technical upgrade did not result in a significant improvement in speech understanding.

DISCUSSION

There was no significant difference in the frequency of reimplantation based on patient age, especially when comparing children and adults. Device failure is by far the most common indication for reimplantation, with no significant difference in implant survival between manufacturers. Patients most often choose the same manufacturer for reimplantation. The likelihood of reimplantation decreases with increasing time since the initial implantation. The indication for reimplantation should be carefully considered, as on average, no improved speech understanding is achieved, regardless of the cause, even with a technical upgrade.

Failure in HiRes Ultra Series Recall Devices Does Not Necessarily Lead to Decrement in Performance

OBJECTIVE

To understand the impact on speech perception for patients experiencing Advanced Bionics V1 series Ultra and Ultra 3D cochlear implant failure.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary academic center.

PATIENTS

Adult patients implanted with V1 series devices.

INTERVENTIONS

Device integrity and speech perception testing.

MAIN OUTCOME MEASURES

consonant-nucleus-consonant and AzBio in quiet speech recognition scores.

RESULTS

At our institution, 116 V1 series cochlear implants were placed in 114 patients. Thirteen devices in prelingual patients were excluded, leaving 103 (89%) for final analysis. Forty-eight (46.6%) devices were considered as failed using the company provided EFI analysis tool. There were 36 (65.5%) of the remaining 55 devices that consistently tested within normal range; the remainder lost to follow-up with unknown status. Among the 48 device failures, 29 were revised and 19 patients were not revised. Among those not revised, 11 self-opted for observation (57.9%). Observed patients, despite impedance changes meeting failure criteria, had no subjective or objective changes in speech perception. Sentence testing scores for failure patients who elected observation (82.9 ± 11.4%) were significantly higher at failure compared with those opting for revision (55 ± 22.8%, p = 0.006). For those undergoing revision surgery, significant improvement in post-activation scores was noted as compared with time of failure with a mean improvement of 12.9% (p = 0.002, n = 24) for consonant-nucleus-consonant word scores and 17.2% (p = 0.001, n = 19) for AzBio in quiet scores.

CONCLUSIONS

Proactive monitoring using EFI identifies a higher rate of Ultra Series V1 device failure than previously reported. However, about 20% of these patients may not have subjective change in hearing or objective decline in test scores and could be observed. Should performance worsen, reimplantation provides significant improvement in speech recognition.

Speech perception in patients submitted to cochlear reimplantation

PURPOSE

To analyze the performance of auditory speech perception (PF) after cochlear implant (CI) replacement surgery and associations with age, times of use of the first CI, deprivation, recovery and use of the second device.

METHODS

The retrospective study analyzed the medical records of 68 participants reimplanted from 1990 to 2016, and evaluated with PF performance tests, considering as a reference, the greater auditory capacity identified during the use of the first CI. Also analyzed were: Etiology of hearing loss; the reasons for the reimplantation; device brands; age range; sex; affected ear; age at first implant; time of use of the first CI, deprivation, recovery and use of the second device. The analyzes followed with the Chi-Square and Spearman, Mann-Whitney and Kruskal-Wallis tests (CI=95%; p≤0.05; Software SPSS®.v22).

RESULTS

Most were children with hearing loss due to idiopathic causes and meningitis. Abrupt stoppage of operation was the most common cause for device replacement. Most cases recovered and maintained or continued to progress in PF after reimplantation. Adults have the worst recovery capacity when compared to children and adolescents. The PF capacity showed a significant association (p≤0.05) with: age at first implant; time of use of the first and second CI.

CONCLUSION

Periodic programming and replacement of the device when indicated are fundamental for the maintenance of auditory functions. Being young and having longer use of implants represent advantages for the development of speech perception skills.

Seven-Year Revision Rates for Cochlear Implants in Pediatric and Adult Populations of an Integrated Healthcare System

OBJECTIVE

We assessed three cochlear implant (CI) suppliers: Advanced Bionics, Cochlear Limited, and MED-EL, for implant revision requiring reoperation after CI placement.

STUDY DESIGN

Retrospective cohort study of integrated-health-system database between 2010 and 2021. Separate models were created for pediatric (age <18) and adult (age ≥18) cohorts.

PATIENTS

Pediatric (age <18) and adult (age ≥18) patients undergoing cochlear implantation within our integrated healthcare system.

MAIN OUTCOME MEASURE

Revision after CI placement. Cox proportional hazard regression was used to evaluate revision risk and adjust for confounding factors. Hazard ratios (HRs) and 95% confidence intervals (CIs) are presented.

RESULTS

A total of 2,347 patients underwent a primary CI placement, and Cochlear Limited was most implanted (51.5%), followed by Advanced Bionics (35.2%) and MED-EL (13.3%). In the pediatric cohort, the 7-year crude revision rate was 10.9% for Advanced Bionics and 4.8% for Cochlear Limited, whereas MED-EL had insufficient cases. In adults, the rates were 9.1%, 4.5%, and 3.3% for Advanced Bionics, MED-EL, and Cochlear Limited, respectively. After 2 years of postoperative follow-up, Advanced Bionics had a significantly higher revision risk (HR = 8.25, 95% CI = 2.91-23.46); MED-EL had no difference (HR = 2.07, 95% CI = 0.46-9.25).

CONCLUSION

We found an increased revision risk after 2 years of follow-up for adults with Advanced Bionics CI devices. Although we found no statistical difference between manufacturers in the pediatric cohort, after 2 years of follow-up, there were increasing trends in the revision probability for Advanced Bionics. Further research may determine whether patients are better suited for some CI devices.

Changes in Revision Cochlear Implantation and Device Failure Profiles

OBJECTIVES

As cochlear implantation (CI) experiences rapid innovations and its indications expand, the characteristics of revision CI (RCI) are evolving. This study investigated changes in the RCI profile and explored their clinical implications.

METHODS

A retrospective chart review was conducted of all CIs performed at a tertiary medical institution between October 2001 and January 2023. The rates of and reasons for RCI were evaluated in relation to the manufacturer and device model. Kaplan-Meier analysis was employed to examine cumulative and device survival curves. Cumulative and device survival rates were additionally analyzed based on age group, period of primary CI, and manufacturer. A Cox proportional hazards model was employed to evaluate the association between RCI and the device manufacturer.

RESULTS

Among 1,430 CIs, 73 (5.1%) required RCI. The predominant reason for RCI was device failure (40 of 73 RCIs [54.8%]), with an overall device failure rate of 2.8%. This was followed by flap-associated problems and migration (nine of 73 RCIs each [12.3%]). Flap retention issues emerged as a new cause in three cases (two involving the CI 632 and one involving the SYNCHRONY 2 implant), and six instances of electrode tip fold-over arose (four for the CI 600 series and two for the CI 500 series). The overall 10-year cumulative and device survival rates were 93.4% and 95.8%, respectively. After excluding models with recall issues, significant differences in cumulative (P =0.010) and device (P =0.001) survival rates were observed across manufacturers.

CONCLUSION

While the overall CI survival rate is stable, device failure persists as the predominant reason for RCI. Moreover, the types of complications leading to revision (including issues with flap retention and electrode tip fold-over) have shifted, particularly for newer implant models. Given the clinical importance of device failure and subsequent reoperation, clinicians should remain informed about and responsive to these trends.

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.

A monocenter, patient-blinded, randomized, parallel-group, non-inferiority study to compare cochlear implant receiver/stimulator device fixation techniques (COMFIT) with and without drilling in adults eligible for primary cochlear implantation

BACKGROUND

During the cochlear implantation procedure, the receiver/stimulator (R/S) part of the implant is fixated to prevent postoperative device migration, which could have an adverse effect on the position of the electrode array in the cochlea. We aim to compare the migration rates of two fixation techniques, the bony recess versus the subperiosteal tight pocket without bony sutures.

METHODS AND ANALYSIS

This single-blind randomized controlled trial will recruit a total of 112 primary cochlear implantation adult patients, eligible for implantation according to the current standard of practice. Randomization will be performed by an electronic data capture system Castor EDC, with participants block randomized to either bony recess or standard subperiosteal tight pocket in a 1:1 ratio, stratified by age. The primary outcome of this study is the R/S device migration rate; secondary outcomes include patient-experienced burden using the validated COMPASS questionnaire, electrode migration rate, electrode impedance values, speech perception scores, correlation between R/S migration, electrode array migration and patient complaints, assessment of complication rates, and validation of an implant position measurement method. Data will be collected at baseline, 1 week, 4 weeks, 8 weeks, 3 months, and 12 months after surgery. All data analyses will be conducted according to the intention-to-treat principle.

DISCUSSION

Cochlear implantation by means of creating a tight subperiosteal pocket without drilling a bony seat is a minimally invasive fixation technique with many advantages. However, the safety of this technique has not yet been proven with certainty. This is the first randomized controlled trial that directly compares the minimally invasive technique with the conventional method of drilling a bony seat.

TRIAL REGISTRATION

Netherlands Trial Register NL9698. Registered on 31 August 2021.

The experience of device failure after cochlear implantation

BACKGROUND

The present study describes the treatment of patients at a tertiary institution who experienced device failure after Cochlear Implantation (CI), as well as identifying prodromic symptoms that could assist in the timely identification and management of device failure.

STUDY DESIGN

Retrospective database review (January 2000-May 2017).

SETTING

Single tertiary hospital.

METHODS

Factors recorded included the etiology of hearing loss; age at first and revision CI surgeries; surgical information, including operation time and approach; electrical outcomes after implantation; device implanted; symptoms of device failure; history of head trauma; and audiologic outcomes as determined by categories of auditory performance (CAP).

RESULTS

From January 2000 to May 2017, 1431 CIs were performed, with 27 (1.9%) undergoing revision surgeries due to device failure. The most common etiology of hearing loss was idiopathic (12/27), followed by cochlear hypoplasia (5/27). Mean age at initial CI was 11.8 (1-72) years, with 21 being pre-lingual and 6 being post-lingual. Of the total devices initially implanted, 80.5% were from Cochlear, 15.9% from MED-EL, and 3.5% from Advanced Bionics. The failure rates of these devices were 1.3%, 3.1%, and 10.0%, respectively. The most suggestive symptom of device failure was intermittent loss of signal. Mean CAP scores were 5.17 before reimplantation and 5.54 and 5.81 at 1- and 3-years, respectively, after reimplantation.

CONCLUSION

The most suggestive symptom preceding device failure was intermittent loss of signal. Patients who present with this symptom should undergo electrical examination for suspected device failure. Audiologic outcomes showed continuous development despite revision surgeries.

Cochlear Implant Revisions Over Three Decades of Experience

IMPORTANCE

The indications, technology, and surgical technique for cochlear implantation have evolved over the last three decades. Understanding the risk of cochlear implant revision (CIR) is important for patient counseling.

OBJECTIVE

The objective of this study was to analyze the rates, indications, and audiologic outcomes for CIR over three decades of experience at a single academic medical center.

DESIGN

A retrospective chart review was performed at a single academic medical center for individuals who underwent cochlear implantation between 1985 and 2022.

SETTING

Single academic medical center.

PARTICIPANTS

Three thousand twenty-five individuals who underwent 3,934 cochlear implant operations from 1985 to 2022.

EXPOSURE

Cochlear implantation.

MAIN OUTCOMES AND MEASURES

Rates, indications, risk factors, and audiologic outcomes for CIR.

RESULTS

There were 276 cases of CIR after primary implantation and an overall revision rate of 7.6% (95% confidence interval, 6.8-8.5%) over 37 years of follow-up with many cases of CIR secondary to Advanced Bionics vendor B and field action failure groups. CIR rates increased sharply through the early and mid-2000s and have since remained stable. Hard or soft device failure was the most common indication for CIR, accounting for 73% of cases. Pediatric patient status and previous CIR were associated with an increased risk of CIR. Audiologic outcomes after CIR were similar to those before device failure.

CONCLUSIONS AND RELEVANCE

CIR remains a common procedure most often performed for device failure. Pediatric patients and those who have undergone previous CIR are at the highest risk for future CIR. Audiologic outcomes remain stable after CIR, and these data will help providers counsel patients at the risk of future CIR and understand the risk factors associated with CIR.

Pediatric cochlear implant explantation and reimplantation over a 32-year period

OBJECTIVES

Cochlear implantation is indicated for pediatric patients with bilateral severe to profound sensorineural hearing loss. The literature reports large variability in cochlear implant (CI) device survival and rates of explantation and reimplantation. This retrospective chart review summarizes CI survival and rates of explantation and reimplantation in pediatric CI recipients at a Canadian tertiary pediatric hospital over 32 years.

METHODS

A retrospective chart review of all pediatric patients who received a Cochlear Corporation® CI between April 1988 and June 2020 was undertaken. Rates of explantation/reimplantation were collected and categorized based on device type and reason for failure (medical, device, and inconclusive failure). Device survival analysis based on implant model was also completed utilizing Kaplan-Meier curves.

RESULTS

512 CIs were implanted over the 32-year period by four surgeons (77.1%, 18.16%, 4.49%, and 0.20%, respectively). Patient age ranged from seven months to 20.4 years. The overall explantation and reimplantation rate was 3.32% (17/512 implants), with seven as a result of device failure (1.37%), nine events of medical failure (1.76%), and one inconclusive failure (0.20%). Cumulative CI survival rates at 5, 10, 15, and 20 years were 98.15%, 96.33%, 95.53%, and 94.39%.

CONCLUSION

The overall institutional CI failure, explantation, and reimplantation rates are lower than the average reported rates in the literature.

Institutional Experience With Cochlear Implants Falling Under the 2020 FDA Corrective Action

OBJECTIVE

To determine the rate of device failure for those cochlear implants falling under the 2020 Food and Drug Administration (FDA) voluntary corrective action.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary otology-neurotology practice.

PATIENTS

Those with cochlear implant failure falling under the FDA corrective action.

INTERVENTIONS

Cochlear implant explant and reimplantation.

OUTCOME MEASURES

Reason for cochlear implant failure, time to failure, symptoms of failure, and benefit from reimplantation.

RESULTS

The overall failure rate was 20.0% (18 of 90 ears); of the failures, 15 of 18 (83.3%) were hard device failures, and 3 of 18 (16.7%) were medical or surgical failures. All hard device failures were confirmed with integrity testing as performed by the company. The average time to integrity testing was 38.0 months. Of the hard failures, 14 of 15 had successful initial activation and benefit. Lack of expected progress was seen in 7 of 15 and a sudden decline in function in 8 of 15. Electrodes 9 to 16 were most often defunct. Significant drops in speech perception were often seen in device failure cases. Three medical/surgical failures were explanted; one had migration of the receiver/stimulator causing discomfort, and the other two had electrode migration after partial insertion. Of the reimplanted patients, 11 of 12 are deriving benefit from their new devices.

CONCLUSIONS

The rate of device failure for the cochlear implants of interest is significantly higher in our series than reported in the initial FDA voluntary field corrective action publication.

Infected Cochlear Implant and Re-implantation in a Pediatric Case

Cochlear implant (CI) surgery is relatively safe, however reports of complications and failure following cochlear implant surgery are higher nowadays due to the increasing number of patients with CI. Herein, we report a case of infected cochlear implant 10 months after surgery. A three-year-six-month-old girl underwent right cochlear implantation for bilateral profound sensorineural hearing loss. From day one until six months after the surgery, it was uneventful and the wound healed well. However, at 10 months post-surgery, she presented with a chronic discharging wound over the previous surgical site. Despite being on IV antibiotics for six weeks and daily dressing, the wound over the implant site keep discharging and eventually the implant was removed two months later. She was later re-implanted with a cochlear implant on the same side at the age of five years 10 months old. Currently, she is showing good speech improvement with the right CI. Her aided hearing threshold is at 30-40 dB at all frequencies. Early diagnosis is crucial, and the proper course of action should be taken as soon as possible if implant failure is suspected. Prior to implant surgery, any potential risk factors that could lead to implant failure should be identified and addressed appropriately to reduce the risk of an infected cochlear implant.

Delayed-onset swelling around the implant after cochlear implantation: a series of 26 patients

PURPOSE

We aimed to clarify the clinical features of delayed-onset swelling around cochlear implants (CI), and to present our experience on how to avoid and address this problem.

METHODS

We performed a retrospective review of all CI cases at our institution between June 2001 and June 2020. Information on postoperative complications of swelling in the receiver area > 3 months after implantation were analyzed, and clinical data sheets were drawn.

RESULTS

Twenty-six of 1425 patients (1.82%) with an age at implantation ranging from 1 to 9 years experienced delayed-onset swelling around the implant. Swelling episodes occurred as early as 4 months, and as late as 178 months after implantation (median, 79.7 months). The predisposing factor in 12 cases was unclear, 7 cases were caused by trauma at the implantation site, 5 cases were without predisposing factors, and 2 cases were related to infection. We found the frequency of delayed-onset swelling after cochlear implantation with different incision was statistically insignificant (P = 0.423). Nineteen patients (73.1%) were cured after one treatment, and five patients (19.2%) relapsed. Follow-up examinations at least 18 months after surgery revealed that all patients experienced a complete recovery.

CONCLUSIONS

Delayed-onset swelling at the receiver site is a long term but not exactly uncommon complication after cochlear surgery and long-term follow-up is eagerly required. It can recur more than once, causing more complex treatment strategies in clinical practice. Conservative treatment first recommended, while needle aspiration should initially be considered in recurrent cases also when the effusion swelling is > 3 ml.

HiRes Ultra Series Recall: Failure Rates and Revision Speech Recognition Outcomes

OBJECTIVE

To report Advanced Bionics (AB) Ultra (V1) and Ultra 3D (V1) cochlear implant (CI) electrode failures and revision speech recognition outcomes for patients at a large CI program.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Patients receiving Ultra (V1) or Ultra 3D (V1) devices as of September 21, 2021.

MAIN OUTCOME MEASURES

Failure rate, revision surgery, speech recognition scores.

RESULTS

To data, 65 (21.1%) of the 308 implanted devices are known failures, with 63 (20.5%) associated with the recent voluntary field corrective action (FCA). Average time to failure was 2.2 ± 1.1 years. Fifty-two patients (82.5%) elected for revision surgery. Among adults, immediate prerevision scores demonstrated a significant decrease from best-achieved scores with the faulty implant, with mean difference of -15.2% (p = 0.0115) for consonant-nucleus-consonant (CNC) and -27.3% (p < 0.0001) for AzBio in quiet. By 3 months postactivation of the revised device, CNC (p = 0.9766) and AzBio in quiet (p = 0.9501) scores were not significantly different than best prerevision scores. Overall, 15 of 19 patients regained or improved their best prerevision CNC score. The current trajectory for FCA device failures is approximately 6% per year.

CONCLUSION

Compared to manufacturer reporting, a high number of patients experienced hard failures of the Ultra (V1) and Ultra 3D (V1) devices. Early identification of failures is possibly because of the diligent use of electrical field imaging testing. Most patients affected by the FCA regain or exceed their prefailure speech recognition score as soon as 3 months after revision surgery.

The Importance of a Preinsertion Integrity Device Test of Cochlear Implants

OBJECTIVES

The surgery of a cochlear implant is a complex interdisciplinary procedure with high quality standards to ensure patients safety and implant durability. An integrity test of the device prior to insertion is an additional tool to improve quality standards by detecting potentially malfunctioning implants without burdening the patient.

METHODS

At the Department of Otorhinolaryngology, University Hospital Frankfurt a. M. (Germany) since 2010 an integrity device test ("pre-insertion telemetry") has been performed prior to the implantation of a cochlear implant. The preinsertion telemetry measures the electrical impedances of the implant electrode contacts in conductive saline solution and thereby confirms regular bidirectional data transmission and electrode integrity. In the case of irregular results with suspected implant malfunction, the device was discarded during surgery and returned to the manufacturer for further technical review. Data and test results of the preinsertion telemetry and from rejected implants (manufacturers' reports) between January 2010 and December 2020 were analyzed.

RESULTS

From 2010 to 2020, 1,926 cochlear implants from three manufacturers were implanted at our institution. All implants had fully functioning bidirectional data transmission. 15 implants had irregular preinsertion telemetry results (electrode circuit failures) and were rejected during surgery. In 13 cases, the manufacturer confirmed implant malfunction. In the last 5 years, only one implant with irregular preinsertion telemetry was detected.

CONCLUSION

Preinsertion telemetry is strongly recommended as a quick and reliable integrity test of the device to confirm the functionality of a cochlear implant.

Photon-Counting Detector CT Virtual Monoengergetic Images for Cochlear Implant Visualization—A Head to Head Comparison to Energy-Integrating Detector CT

Cochlear implants (CIs) are the primary treatment method in patients with profound sensorineural hearing loss. Interpretation of postoperative imaging with conventional energy-integrating detector computed tomography (EID-CT) following CI surgery remains challenging due to metal artifacts. Still, the photon-counting detector (PCD-CT) is a new emerging technology with the potential to eliminate these problems. This study evaluated the performance of virtual monoenergetic (VME) EID-CT images versus PCD-CT in CI imaging. In this cadaveric study, two temporal bone specimens with implanted CIs were scanned with EID-CT and PCD-CT. The images were assessed according to the visibility of interelectrode wire, size of electrode contact, and diameter of halo artifacts. The visibility of interelectrode wire sections was significantly higher when reviewing PCD-CT images. The difference in diameter measurements for electrode contacts between the two CT scanner modalities showed that the PCD-CT technology generally led to significantly larger diameter readings. The larger measurements were closer to the manufacturer’s specifications for the CI electrode. The size of halo artifacts surrounding the electrode contacts did not differ significantly between the two imaging modalities. PCT-CT imaging is a promising technology for CI imaging with improved spatial resolution and better visibility of small structures than conventional EID-CT.

Cochlear implant explantation: An in vitro model to evaluate electrode explant force and trauma

OBJECTIVES

Removal of a cochlear implant and its intracochlear electrode array is sometimes necessary, potentially causing cochlear explant trauma. Explantation typically occurs years post-implantation by which time reactive tissue has formed around the electrode. We aimed to create an in-vitro electrode explant model to examine explant forces and intracochlear trauma across multiple electrode types and insertion depths.

STUDY DESIGN

An in-vitro model using gel to represent tissue surrounding the electrode was developed. Pre-curved electrodes and straight electrodes at different insertion depths (20mm, 25mm, 28mm) were explanted from the model. During explantation, explant force was measured, and high-definition videos were recorded to capture electrode exit path and gel disruption.

RESULTS

Explant force patterns varied based on electrode position in the scala tympani. Explant forces did not correlate with gel disruption, which represented explant trauma. The least gel disruption occurred with pre-curved electrodes and the under-inserted straight electrode. The greatest disruption occurred with the overly inserted straight electrode.

CONCLUSION

An in-vitro model using gel to mimic tissue surrounding the electrode may provide insights into potential electrode explant trauma. Explant force did not correlate with explant trauma in our model. Pre-curved electrodes and shallower insertion depth of a straight electrode resulted in the least amount of explant trauma.

Infectious Complications Following Cochlear Implant: Risk Factors, Natural History, and Management Patterns

OBJECTIVE

To describe the natural history, detail the treatment patterns, and identify the risk factors for cochlear implant (CI) infections in a large US cohort.

STUDY DESIGN

Retrospective study based on insurance claims.

SETTING

Optum Data Mart database: 6101 patients who received CIs from 2003 to 2019.

METHODS

Infections, treatments patterns, and timelines were described. A multivariable logistic regression model was used to assess the association between postoperative oral antibiotics and CI infection.

RESULTS

The cohort includes 4736 (77.6%) adults and 1365 (22.4%) children. Between adult and pediatric patients, rates of CI infection (5.1% vs 4.5%, P = .18) and explantation (1.2% vs 0.8%, P = .11) were not significantly different. Infections typically occurred within 5 months of surgery. Children were diagnosed with CI infection earlier than adults (median difference, -1.5 months; P = .001). Postoperative oral antibiotic supply was not associated with lower risk of CI infection in either children or adults. However, among adults, otitis media was associated with higher odds of CI infection (odds ratio, 1.41; P < .001), while higher income was associated with lower odds of CI infection (odds ratio, 0.71; P = .03).

CONCLUSIONS

Postoperative oral antibiotics were not associated with lower risk of infection or interventions. Otitis media episodes and lower income were associated with increased risk of infection among adults as well as intervention overall. Infection typically presented within the first 6 months after surgery, with children presenting earlier than adults. Overall, our findings serve as a resource for providers to consider in their care of patients with CIs.

Cochlear implant failure: diagnosis and treatment of soft failures

Objective

Early diagnosis of cochlear implant failures (CIF) is a critical part of post-implantation follow-up. Diagnosis is challenging and time consuming. Our study aimed to describe diagnoses of CIF with emphasis on soft failures (SF), focusing on symptoms, time from symptoms to replacement, and differences between SF and hard failures (HF).

Methods

A retrospective review of medical records in a tertiary care referral paediatric medical centre including all patients who experienced CIF during 2000-2020.

Results

Of 1004 CI surgeries, 72 (7.2%) cases of CIF were included, of which 60 CIF were in children (mean age 3.1 years). Twenty-five cases were due to HF, 26 SF, and 21 due to medical reasons. Patients with SF were more likely to present with headache, dizziness, or tinnitus compared with those with HF. Facial stimulation and disconnections were more common in implants from Advanced Bionics, dizziness and tinnitus in Cochlear, and poor progression in Med-El. Mean time from symptoms to implant replacement surgery was longer in cases with SF compared to HF.

Conclusions

SF poses a diagnostic challenge. Symptoms such as headache, dizziness, and tinnitus are common. Diagnosis of failure should often be based on assessments of the implant and rehabilitation teams.

Potential Implications of Slim Modiolar Electrodes for Severely Malformed Cochleae: A Comparison With the Straight Array With Circumferential Electrodes

Objectives

Malformations of the inner ear account for approximately 20% of cases of congenital deafness. In current practice, straight arrays with circumferential electrodes (i.e., full-banded electrodes) are widely used in severely malformed cochleae. However, the unpredictability of the location of residual spiral ganglion neurons in such malformations argues against obligatorily using full-banded electrodes in all cases. Here, we present our experience of electrically evoked compound action potential (ECAP) and radiography-based selection of an appropriate electrode for severely malformed cochleae.

Methods

Three patients with severely malformed cochleae, showing cochlear hypoplasia type II (CH-II), incomplete partition type I (IP-I), and cochlear aplasia with a dilated vestibule (CADV), respectively, were included, and the cochlear nerve deficiency (CND) was evaluated. A full-banded electrode (CI24RE(ST)) and slim modiolar electrode (CI632) were alternately inserted to compare ECAP responses and electrode position.

Results

In patient 1 (CH-II with CND), who had initially undergone cochlear implantation (CI) using a lateral wall electrode (CI422), revision CI was performed due to incomplete insertion of CI422 and resultant unsatisfactory performance by explanting the CI422 and re-inserting the CI24RE(ST) and CI632 sequentially. Although both electrodes elicited reliable ECAP responses with correct positioning, CI24RE(ST) showed overall lower ECAP thresholds compared to CI632; thus, CI24RE(ST) was selected. In patient 2 (IP-I with CND), CI632 elicited superior ECAP responses relative to CI24RE(ST), with correct positioning of the electrode; CI632 was chosen. In patient 3 (CADV), CI632 did not elicit an ECAP response, while meaningful ECAP responses were obtained with the CI24RE(ST) array once correct positioning was achieved. All patients’ auditory performance markedly improved postoperatively.

Conclusion

The ECAP and radiography-based strategy to identify an appropriate electrode may be useful for severely malformed cochleae, leading to enhanced functional outcomes. The practice of sticking to full-banded straight electrodes may not always be optimal for IP-I and CH-II.

A retrospective review of cochlear implant revision surgery: a 24-year experience in China

PURPOSE

We aimed to analyse the reasons behind the need for cochlear implant revision surgeries, as well as the rate at which they occur, to reduce the revision surgery rate for non-device failures. We also aimed to elucidate the cumulative survival and device survival rates in different age groups.

METHODS

This retrospective single cohort study reviewed 4563 cochlear implant surgeries and 119 revision surgeries performed at a tertiary referral hospital in China between 1996 and 2019. Kaplan-Meier curves were used to calculate the cumulative survival and device survival rates.

RESULTS

The revision surgery rate was 2.61%. The reasons for revision included device (73.1%) and non-device (26.9%) failures. The most common reasons were hard device (47.1%) and non-device failure (28.6%). The 10- and 20-year cumulative survival rates were 96.8% and 96.7%, respectively. Younger children were more likely to undergo a second surgery.

CONCLUSION

This study is the longest study about revision surgery in China. Cochlear implantation is a reliable treatment. It has a low complication rate in patients with sensorineural hearing loss. Children have a higher revision rate than adults. Doctors should be aware of each complication and perform the appropriate procedure.