Single Intravenous High Dose Administration of Prednisolone Has No Influence on Postoperative Impedances in the Majority of Cochlear Implant Patients

Impedance Change as an Indicator of Cochlear Implant Failure

OBJECTIVE

In February 2020, Advanced Bionics initiated a field action notice to remove the MS Ultra (V1) implant from circulation. In this study, we quantify a single site's incidence with device failure and examine the relationship between impedance change and declining speech perception.

STUDY DESIGN

Retrospective/cohort study.

SETTING

Tertiary healthcare center.

PATIENTS

Forty-nine adult patients (52 devices) were implanted between October 2017 and December 2019, with the following exclusion criteria: <18 years of age, medical/surgical failures, and lack of English-language proficiency.

INTERVENTIONS

Diagnostic.

MAIN OUTCOME MEASURES

Postoperative speech perception (AzBio sentence test) scores at 12 months postactivation were compared with repeat testing at 6- to 12-month intervals. Degree of change in impedances from 1 month postactivation was analyzed at similar intervals. Device failures were suspected when impedance levels on three or more electrodes dropped to <3.5 kΩ and AzBio scores declined >15%. Device failures were confirmed through analyses completed by the manufacturer.

RESULTS

To date, 21% (11/52) of devices have met all three criteria for a confirmed failure with an average decline in speech perception of 27.7 ± 22%. The average length of time for detection of device failure was 21.9 ± 5 months postimplantation. An additional 7 devices (13%) are currently being monitored for failure but have not yet met full criteria. There was no predictive relationship between degree of impedance change and speech perception scores. Electrodes along the entire array (channels 1-16) can be affected.

CONCLUSIONS

Impedance values can be used as a reliable indicator of device malfunction, thus facilitating patient counseling and early intervention. No correlation was identified between impedance changes and speech perception scores.

Dual Drug Delivery in Cochlear Implants: In Vivo Study of Dexamethasone Combined with Diclofenac or Immunophilin Inhibitor MM284 in Guinea Pigs

Cochlear implants are well established to treat severe hearing impairments. Despite many different approaches to reduce the formation of connective tissue after electrode insertion and to keep electrical impedances low, results are not yet satisfying. Therefore, the aim of the current study was to combine the incorporation of 5% dexamethasone in the silicone body of the electrode array with an additional polymeric coating releasing diclofenac or the immunophilin inhibitor MM284, some anti-inflammatory substances not yet tested in the inner ear. Guinea pigs were implanted for four weeks and hearing thresholds were determined before implantation and after the observation time. Impedances were monitored over time and, finally, connective tissue and the survival of spiral ganglion neurons (SGNs) were quantified. Impedances increased in all groups to a similar extent but this increase was delayed in the groups with an additional release of diclofenac or MM284. Using Poly-L-lactide (PLLA)-coated electrodes, the damage caused during insertion was much higher than without the coating. Only in these groups, connective tissue could extend to the apex of the cochlea. Despite this, numbers of SGNs were only reduced in PLLA and PLLA plus diclofenac groups. Even though the polymeric coating was not flexible enough, MM284 seems to especially have potential for further evaluation in connection with cochlear implantation.

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.

Cochlear Implantation in Obliterated Cochlea: A Retrospective Analysis and Comparison between the IES Stiff Custom-Made Device and the Split-Array and Regular Electrodes

Anatomical malformations, obliterations of the cochlea, or re-implantations pose particular challenges in cochlear implantation. Treatment methods rely on radiological and intraoperative findings and include incomplete insertion, the implantation of a double array, and radical cochleostomy. In addition, a stiff electrode array, e.g., the IE stiff (IES) custom-made device (CMD, MED-EL), was prescribed individually for those special cases and pre-inserted prior to facilitate cochlear implantation in challenging cases. Data on outcomes after implantation in obliterated cochleae are usually based on individual case reports since standardised procedures are lacking. A retrospective analysis was conducted to analyse our cases on obliterated cochleae treated with MED-EL devices in order to allow the different cases to be compared. Impedances and speech perception data of patients treated with the IES CMD and the double array were retrospectively compared to patients treated with a STANDARD or FLEX electrode array (the REGULAR group). Patients with a Split-Array CMD had a poor speech perception when compared to patients treated with the IES CMD device. Thus, the IES CMD can successfully be used in patients with obliterated cochleae who would otherwise be non-users, candidates for a Split-Array CMD, or candidates for partial insertion with insufficient cochlear coverage.

Cochlear implant in immune mediated inner ear diseases: Impedance variations and clinical outcomes

OBJECTIVE

Immune-mediated inner ear disease (IMIED) might cause severe/profound hearing loss and these patients are considered ideal candidates to cochlear implant (CI) surgery. The aim of the study was to evaluate impedance changes over time.

METHOD

The Study Group (SG) was composed of CI IMIED patients (31 ears) and a Control Group (CG) of CI patients with hearing loss not related to their immune system (31 ears). Audiological performance and impedance values were measured and compared amongst groups at 3, 6, 12 and 18 months following the fitting sessions.

RESULTS

Speech perception was significantly better for SG in word and sentence recognition in quiet. Impedance values were, on average, significantly higher for apical and middle electrode segments in SG compared to CG at the 3- month follow-up and were maintained over time. Additionally, a subset of SG patients (active patients) experienced significantly greater impedance fluctuation corresponding to clinical symptom reactivation.

CONCLUSION

IMIED patients achieve good audiological performance. However, the relapsing inflammation could change the inner ear environment, causing impedance fluctuations and, consequently, more frequent CI fittings. Additionally, impedance evaluation could be utilized as an early warning sign of IMIED recurrence and as an aid to therapeutic decision-making.

Does early activation within hours after cochlear implant surgery influence electrode impedances?

OBJECTIVE

This study aims to determine if early device activation can influence cochlear implant electrode impedances by providing electrical stimulation within hours after cochlear implant surgery.

DESIGN

Electrode impedances were measured intraoperatively, at device activation, and one-month after device activation in three groups: users whose devices were activated (1) on the same day (Same Day), (2) the next day (Next Day), and (3) 10-14 days (Standard), after cochlear implant surgery.

STUDY SAMPLE

Electrode impedances are reported in fifty-one patients implanted with a Cochlear™ Nucleus^® Cochlear Implant.

RESULTS

Compared to intraoperative levels, impedances dropped within hours for the Same Day activation group (p < 0.001) and continued dropping on the next day after surgery (p < 0.001). Similarly, electrode impedances were significantly (p < 0.001) lower at device activation for the Next Day group as compared to their intraoperative measurements. For Standard activation, impedances increased significantly from intraoperative levels, prior to device activation (p < 0.001). One-month after initial activation, impedances were not statistically different between the Same Day, Next Day, and Standard activation groups.

CONCLUSIONS

Early device activation does not influence long-term impedances in a clinically meaningful manner.

Impedance Values Do Not Correlate With Speech Understanding in Cochlear Implant Recipients

OBJECTIVE

To evaluate a possible correlation between impedance values and speech perception after cochlear implantation.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS AND INTERVENTION

All patients implanted with a MedEl Flex28 device in our department with complete audiometric data (Freiburger monosyllabic testing at 65 dB, Hochmaier-Schulz-Moser testing in quiet and in 10 dB noise) and impedance measurements at the 1-year refitting appointment were enrolled in this study. Further inclusion criteria were age > 17 years, native speakers, and no use of electric-acoustic-stimulation.

MAIN OUTCOME MEASURES

Mean values for impedances were calculated over all electrode contacts and separately for basal, medial, and apical regions. These data were correlated statistically (Pearson's correlation) with speech testing results. Furthermore, groups of patients with extreme values were built and compared against each other and against the rest of the collective.

RESULTS

Impedance values did not correlate significantly with speech performance in any of the audiometric tests neither for all electrode contacts nor for specific clusters of contacts. Patients with the lowest impedances did not perform statistically different than patients with the highest impedances in any condition.

CONCLUSION

To our knowledge, this is the first data on a possible correlation between impedances and speech perception. The extent of the impedances as a benchmark for a good performance in speech discrimination tests could not be verified. Further prospective studies, possibly with more precise diagnostic tools, should be carried out to define the value of impedance measurements for cochlear implantation provision.

Dose-Dependent Transient Decrease of Impedances by Deep Intracochlear Injection of Triamcinolone With a Cochlear Catheter Prior to Cochlear Implantation-1 Year Data

Administration of low-dose steroids via a catheter inserted into the cochlea to apply pharmaceuticals to more apical regions was previously shown not to be sufficient for long-term reduction of electrode impedances. The aim of the present study was to investigate the effect of intra-cochlear high-dose triamcinolone application on impedances in cochlear implant recipients. Patients received low-dose (4 mg/ml; n = 5) or high-dose (20 mg/ml; n = 5) triamcinolone via a cochlear catheter just prior to the insertion of a Med-El Flex28 electrode. Impedances were measured at defined time points from intra-operatively up to 12 months after first fitting and retrospectively compared with a control group (no steroid application). Patients who received a high-dose application of crystalloid triamcinolone showed significantly reduced impedances in the first fitting measurements compared to the control group. This effect was no longer detectable in patients of the low-dose group at that time. Looking at the different regions of the electrode, the impedance values were lowered significantly only at the basal and medial contacts. At later time points, there were no significant differences between any of the groups. This is the first study to demonstrate a dose-dependent reduction of impedances by deep intra-cochlear injection of triamcinolone in cochlear implant patients. With a high-dose, single application of triamcinolone using a cochlear catheter prior to insertion of a Flex28 electrode, the impedances can be significantly reduced up to and including the first fitting. Although the effect was longer lasting than when compared to low-dose triamcinolone, it was also not permanent.