Evolution of impedance values in two different electrode array designs following activation of cochlear implants 1 day after surgery: A study of 58 patients

Early activation of cochlear implants: a systematic review and narrative synthesis

BACKGROUND

Device activation typically occurs four weeks post cochlear implant surgery. Emerging evidence suggests earlier activation is feasible and beneficial, giving patients quicker access to sound and rehabilitation.

OBJECTIVES

Assess current literature for effects of early cochlear implant activation.

METHODS

Electronic searches of Medline/PubMed, AMED, EMBASE, CINAHL and the Cochrane Library following PRISMA guidelines. Studies investigating any aspect of early activation were included for review.

RESULTS

From 15 studies, 625 patients received early activation, compared with 243 patients in the control groups. Early activation was considered as within 7 days post-operatively with 12 studies reporting within 1 day post-operatively, compared with standard activation of 9-46 days post-operatively in the control group. Some studies indicated earlier low levels of impedance in the early activation group. Magnet strength adjustment or off-ear processor wear was often recommended within the early activation cohort. Complication rates were low in both groups. Early activation improved patient satisfaction and anxiety levels without detriment to speech recognition or rehabilitation.

CONCLUSION

Early cochlear implant activation is feasible and allows patients with no contraindications, earlier access to auditory perception and rehabilitation and reduces anxiety linked to delay in activation. Further evidence is required to monitor long-term effects of early activation.

Postoperative Impedance-Based Estimation of Cochlear Implant Electrode Insertion Depth

OBJECTIVES

Reliable determination of cochlear implant electrode positions shows promise for clinical applications, including anatomy-based fitting of audio processors or monitoring of electrode migration during follow-up. Currently, electrode positioning is measured using radiography. The primary objective of this study is to extend and validate an impedance-based method for estimating electrode insertion depths, which could serve as a radiation-free and cost-effective alternative to radiography. The secondary objective is to evaluate the reliability of the estimation method in the postoperative follow-up over several months.

DESIGN

The ground truth insertion depths were measured from postoperative computed tomography scans obtained from the records of 56 cases with an identical lateral wall electrode array. For each of these cases, impedance telemetry records were retrieved starting from the day of implantation up to a maximum observation period of 60 mo. Based on these recordings, the linear and angular electrode insertion depths were estimated using a phenomenological model. The estimates obtained were compared with the ground truth values to calculate the accuracy of the model.

RESULTS

Analysis of the long-term recordings using a linear mixed-effects model showed that postoperative tissue resistances remained stable throughout the follow-up period, except for the two most basal electrodes, which increased significantly over time (electrode 11: ~10 Ω/year, electrode 12: ~30 Ω/year). Inferred phenomenological models from early and late impedance telemetry recordings were not different. The insertion depth of all electrodes was estimated with an absolute error of 0.9 mm ± 0.6 mm or 22° ± 18° angle (mean ± SD).

CONCLUSIONS

Insertion depth estimations of the model were reliable over time when comparing two postoperative computed tomography scans of the same ear. Our results confirm that the impedance-based position estimation method can be applied to postoperative impedance telemetry recordings. Future work needs to address extracochlear electrode detection to increase the performance of the method.

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

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

Early activation after cochlear implantation: a systematic review

PURPOSE

To systematically review the outcomes of early activation following cochlear implantation (CI) based on the findings from different studies in the literature.

METHODS

A comprehensive search strategy was conducted through different databases to identify relevant articles. Our outcomes included impedance levels, rates of complications, hearing and speech perception performance, and patients' satisfaction levels.

RESULTS

The total number of included studies in this systematic review is 19, which recruited 1157 patients, including 857 who underwent early activation following CI. Seventeen studies investigated impedance levels or feasibility rates of early activation approaches. Most of these studies (n = 10) reported that mean impedance levels remarkably decreased within the first day-to-month (first measurement) post-activation. In addition, all 17 studies showed that impedance levels finally normalize and become comparable with intraoperative levels or the conventional activation group. Seventeen studies reported the occurrence of complications in their population. Ten of these studies indicated that none of their patients developed any post-operative complications after early activation. Seven studies reported the development of some minor complications, including pain 9.2% (28/304), infection 4.7% (13/275), swelling 8.2% (25/304), vertigo 15.1% (8/53), skin hyperemia 2.2% (5/228), and others 16.4% (9/55). Hearing and speech perception was assessed in six studies, which showed a remarkable improvement in their patients. Three studies investigated patients' satisfaction and showed high satisfaction levels. Only one report investigated the economic advantages of early activation.

CONCLUSION

Early activation is safe and feasible and does not impact the hearing and speech outcomes of the patients undergoing CI procedures.

Very early activation of cochlear implants: A review of the literature

Cochlear implantation (CI) has become the standard treatment for patients with severe-to-profound hearing loss. To date, an estimated 750,000 individuals spanning the entire lifecycle have benefited from this life-changing technology. Traditionally, the device is not "activated" for 3 to 4 weeks after surgery. However, an increasing number of centers have recently begun to question the conventional wisdom that several weeks are necessary and are activating their patients' device sooner after CI. This review aimed to provide a comprehensive insight to better understand the feasibility, outcomes, benefits, and limitations of very early cochlear implant activation. Data sources from published medical literature were reviewed. A detailed examination and summary were provided. History and safety were also emphasized. It was observed that approximately 20 studies have reported their experience with very early cochlear implant activation, ranging from the day of surgery to 1 week. Outcome measures are disparate, although there is general agreement that early activation is not only feasible but also provides some real-life benefits to patients and caregivers. The surgical, electrophysiological, audiological, and other outcomes were also reviewed. Very early activation is safe and beneficial in patients with cochlear implants. Many CI centers believe that such a process can lead to improvements in both patient-centered and fiscally responsible care. Although not ideal for all patients, cochlear implant programs may consider this option for their patients.

Effect of initial switch-on within 24 hours of cochlear implantation using slim modiolar electrodes

Reducing electrode impedance is an important factor in improving the functional benefits of cochlear implants (CIs). The immediate effect of early switch-on within 24 h of surgery on impedance among CI recipients with various types of electrodes has been reported previously; however, the immediate change and the evolution of electrode impedances of slim modiolar electrodes after early switch-on within 24 h of implantation has not. Therefore, the focus of this retrospective cohort study of CI patients was to compare the effect of early switch-on (n = 36) and conventional switch-on (n = 72) 2–4 weeks post-operation on impedance. Compared with impedance measured intraoperatively, our results demonstrate a significant decrease in impedance from 11.5 to 8.9 kΩ (p < 0.001) at 2–4 weeks after implantation in the early switch-on group, which sharply contrasted with elevated impedance values for conventional switch-on 2–4 weeks after implantation (from 10.7 to 14.2 kΩ, p = 0.001). Notably, a comparatively lower impedance than the conventional switch-on protocol was observed for up to 2 months post-operation. Most importantly, a much earlier stabilization of impedance can be achieved with the early switch-on protocol coupled with the slim modiolar electrode array compared to the conventional switch-on protocol, offering the advantage of reducing the number of required mapping sessions in the early stages of rehabilitation.

Feasibility of Day Surgery for Cochlear Implantation under Conscious Sedation with Same-Day Fitting

OBJECTIVES

To evaluate the feasibility of performing cochlear implantation under conscious sedation (CS) as day surgery with same-day fitting.

MATERIALS AND METHODS

All patients underwent cochlear implantation under CS between November 2017 and April 2018. The data collected included demographic information, preoperative clinical characteristics, surgical details, postoperative fitting information, and side effects, if any.

RESULTS

Nine patients had 11 cochlear implants (CIs) placed under CS (2 patients received bilateral CIs). One patient's data were excluded from the audiological results because conversion to general anesthesia (GA) was necessary. One patient (11%) vomited just before the end of the procedure. Seven patients had uneventful procedures. Eight (88%) patients were discharged home the same day. There was a statistically significant difference in recovery time between the CS group and the GA group (t=-2.26, df=12, p<0.05). In the CS group, there was no statistically significant change in the maximum comfortable loudness level for all electrodes from the day of the surgery to the following day. However, there was a statistically significant difference in the threshold levels of all electrodes from the day of the surgery to the following day (Z=-2.04, N=120, p<0.05). Further analysis revealed a statistically significant difference in the four most apical electrodes (Z=-3.496, N=40, p<0.0001), but not in the middle or basal electrodes.

CONCLUSION

Cochlear implantation can be performed under CS with careful patient selection. This approach facilitates same-day fitting and day surgery by minimizing comorbidity.

High Electrode Impedance Values in Pediatric Cochlear Implant Recipients May Imply Insufficient Auditory and Language Skills Development

Background: Measurements of electrode impedance values are routinely performed after cochlear implantation. The primary objective of the study was to determine if pediatric, prelingually deafened patients with different postoperative performances showed significantly different impedance values one year after implantation. Methods: This study comprised 42 pediatric cochlear implant recipients provided with the device in a single academic tertiary referral center between 1 January 2000, and 31 December 2016. Medical chart analysis was performed in order to assess evolution of impedance values during the first postoperative year on a monthly basis. Electrode impedance values measurements one year postoperatively were compared between children with successful and unsuccessful auditory and language skills development assessed using the EARS protocol (a name of a performance test). Furthermore, values were compared among recipients of different implant types and among different cochlear segments. Results: A gradual rise of average impedance values was found during the first months of implant use (1st month, 7.32 kΩ; 3rd month, 7.86 kΩ) with the peak at the 4th postoperative month (7.96 kΩ), followed by a gradual decrease towards the 12th month (6th month, 7.62 kΩ; 12th month, 6.86 kΩ). Lower values at the 12th postoperative month were observed in recipients with successful development compared to patients presented with unsuccessful development (6.22 kΩ vs. 7.82 kΩ; p = 0.001). Mean impedance values were different when compared among cochlear segments and among different implant types. Conclusion: High electrode impedance values one year after implantation in pediatric patients may imply insufficient auditory and language skills development. Further studies are needed in order to validate our results.

Rounded Insertion Technique for Cochlear Implantation Surgery to Treat Cystic Inner Ear Malformation

OBJECTIVE

This article outlines the advantages and applicability of the rounded insertion technique of cochlear implants in patients with cystic inner ear malformation. This technique enables the insertion of the maximum number of electrodes and prevents the unwanted entry of electrodes into the internal auditory canal.

METHODS

We conducted a retrospective chart review of consecutive patients with cochlear hypoplasia (CH) and/or common cavity (CC) who underwent CI (cochlear implantation) via rounded insertion technique. The position of the electrode array in each patient was confirmed postoperatively via X-ray, and the number of functional electrodes was confirmed during the mapping process.

RESULTS

This study included five male and two female patients (median age: 3 years; age range: 2-7 years). Among the seven patients, four received a cochlear implant on the right side, one on the left side, and two bilaterally. Of the nine ears, six were cases of CH, and three were CC. All cochlear implant surgeries via rounded insertion technique were completed without complications. The maximum number of electrode contacts with fair function in the cystic cochlea was confirmed via postoperative X-ray and the subsequent mapping process.

CONCLUSION

This consecutive series of patients demonstrated the safety and reliability of rounded insertion technique for CI in patients with CH and/or CC.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:2229-2233, 2020.