Cochlear Implant Impedance Fluctuation in Ménière's Disease: A Case Study

Role of prior intratympanic gentamicin and corticosteroids therapy on speech understanding in patients with Menière's disease after cochlear implantation

AIM

Intratympanic injection of corticosteroids (ITC) and gentamicin therapy (ITG) are widely used treatments for vertigo in Meniere's disease (MD). Even though studies show good results after cochlea implantation (CI) in MD patients when compared to non-MD groups, there is no indication on the effect of ITC and ITG prior to CI on hearing after CI. This study compares the post-operative hearing of CI patients with and without MD and patients who have received ITG or ITC prior to CI.

METHODS

In a retrospective case control study, adult patients with MD who received CI from 2002 till 2021 were compared to a matched control group of CI patients without MD. Patients with prior ITC/ITG were extracted from MD group. Pre-operative audiological results were measured and trends across post-operative monosyllabic word recognition score at 65 decibels (WRS65CI) at switch-on, 3-6 months, 1 year and last yearly value were analyzed across all groups.

RESULTS

28 MD ears were compared with 33 control ears. From MD ears 9 had received ITG and 6 ITC prior to CI. WRS65CI increased significantly with time within MD and control groups, but no difference in WRS65CI was found between these 2 groups. ITG ears showed fluctuating WRS65CI after CI with no change across time, while ITC ears showed significant increase in trend of WRS65CI values across time.

CONCLUSION

MD and non-MD patients showed comparable hearing results after CI. Prior ITC might positively influence hearing preservation after CI in MD patients whereas ITG group showed fluctuating hearing.

Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics

OBJECTIVE

To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI).

STUDY DESIGN

Retrospective and prospective case series.

PATIENTS

Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited.

INTERVENTIONS

Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted.

MAIN OUTCOME MEASURES

Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests.

RESULTS

Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients.

CONCLUSION

High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.

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.

Cochlear implant outcomes in patients with Meniere's disease: a large case series

OBJECTIVE

To perform a matched cohort study to assess whether patients with Meniere's Disease (MD) require more intensive auditory rehabilitation following cochlear implantation (CI) and identify factors that may affect outcomes in patients with MD.

METHODS

A retrospective case review was performed. MD and control patients were matched for age, biological sex, implant manufacturer and electrode design. Outcomes measured were speech scores, number of visits to audiology department following switch-on, and post-operative active MD.

RESULTS

Forty consecutive implanted MD patients were identified between May 1993 and May 2019. Patients with active MD following CI required significantly more visits to the audiology department compared to controls (P < 0.01) and patients who had inactive MD post-operatively (P < 0.01). However, in MD patients, active MD was less likely following CI (P = 0.03). In patients who continued to experience active MD post-operatively, further medical and surgical ablative intervention was required to control ongoing Meniere's attacks.

CONCLUSION

We present the largest case series of performance outcomes in CI patients with MD. Although speech outcomes in MD patients are comparable to controls, patients with active MD pre-operatively are more likely to experience variation in CI performance requiring a prolonged period of auditory rehabilitation compared to inactive preoperative MD.

Electrode Impedance Fluctuations and Sudden Decline in Cochlear-Implant Benefit

OBJECTIVE

The main objective of this clinical capsule was to outline the narrative of three teen cochlear implant (CI) users who experienced a sudden increase in their CI electrode impedance values, which coincided with decreased overall speech perception ability. In addition, the study explored the following questions: Are there any similarities between cases? What recommendations should be made for continuing treatment regarding these cases?

PATIENTS

Three teenagers who reported sudden change in CI benefit were included in this study.

INTERVENTIONS

Electrode impedance values and speech identification scores were obtained routinely during the CI mapping appointments. Specifically, word and sentence recognition scores were obtained using the Consonant-Nucleus-Consonant word list and the AZBio sentence test, respectively. Both patient 1 and patient 2 underwent CI reimplantation operations as a result of their perceived difficulties and decreased impedances. Patient 3 did not undergo reimplantation surgery.

MAIN OUTCOMES

All three patients' CI electrode impedances and speech perception scores eventually stabilized over time. No relationship could be drawn between revision surgery and stabilization of CI electrode impedances and speech perception scores.

CONCLUSIONS

Overall, we found no similarities between cases that could potentially explain the sudden electrode impedance value increase or the decrease in speech perception scores. Each case should be evaluated uniquely and carefully for CI revision operations by frequent monitoring, including mapping and speech perception testing. The most common factor contributing to each teen's eventual resolution of electrode impedance values and speech perception scores was time.

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.

Fluctuation in electrical hearing in a Morbus Meniere's patient

The glycerol test is an easy-to-use instrument to elucidate fluctuations of electrical hearing in patients with Meniere's disease and it might be also used as a therapeutic option.

Cochlear Implantation in Meniere's Disease: A Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

Meniere's disease (MD) is a debilitating condition characterized by hearing loss, vertigo, and tinnitus. The objective of this study was to systematically investigate outcomes in MD after cochlear implantation (CoI), with and without labyrinthectomy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of articles in Medline and Embase was performed to identify all studies of patients with MD who underwent CoI. This analysis evaluates outcomes of speech recognition, pure tone audiometry, vertigo, tinnitus, and quality of life.

RESULTS

Of 321 studies identified, 37 were included, involving 216 patients. Mean age at implantation was 61.4 years (range 27-85 years) with average length of follow-up at 1.7 years (range 0-9 years). Forty-four (20.4%) patients underwent labyrinthectomy. Meta-analysis demonstrated significant improvements in audiometric outcomes following CoI. There was a statistically significant improvement in Hearing in Noise Test performance, with a mean difference improvement of 44.7 (95% confidence interval [CI] [8.8, 80.6]) at 6 months and 60.1 (95% CI [35.3, 85.0]) at 12 months. The Freiburger Monosyllabic Test (FMT) and Consonant-Nucleus-Consonant (CNC) also improved significantly, with mean difference improvements of 46.2 (95% CI [30.0, 62.4]) for FMT and 19.3 (95% CI [8.1, 30.4]) for CNC. There was a statistically significant decrease in tinnitus, as measured by a mean difference reduction of 48.1 (95% CI [1.0, 95.2]) in the Tinnitus Handicap Index.

CONCLUSIONS

CoI with and without simultaneous labyrinthectomy is a viable treatment option for patients with MD, yielding high rates of tinnitus suppression and vertigo control. Post-CoI MD patients demonstrate similar postoperative speech perception outcomes to non-MD implant recipients. Laryngoscope, 131:1845-1854, 2021.

Effect of exceeding compliance voltage on speech perception in cochlear implants

OBJECTIVES

In cochlear implants, the maximum current I (Amperes) that can be delivered on a cochlear implant electrode is determined by V = I * R, where V = compliance voltage (Volts) and R = electrode impedance (Ohms). Generally, electrode impedances are measured during each clinical visit and are used to set electrical stimulation parameters in cochlear implants. However, electrode impedances can rise during the course of cochlear implant use and lead to electrical stimulation voltage requirements exceeding the maximum compliance voltage of the medical device. Electric stimulation requirements that exceed the compliance voltage lead to clipping of the biphasic electrical pulse (current going into the cochlea) and are known to adversely affect cochlear implant outcomes.

DESIGN

Thirteen (11 unilateral and 2 bilateral) Advanced Bionics cochlear implant patients with a HiRes 90k™ cochlear implant participated in this study. Speech perception scores were measured using the patient's baseline clinical program with the most comfortable loudness levels (M-levels) and the following four test programs: (1) stimulation clipped at 15% below clinical M-levels (15%C) (2) stimulation clipped at 30% below clinical M-levels (30%C) (3) M-levels decreased by 15% (15%M) and (4) M-levels decreased by 30% (30%C). Speech perception scores were measured using AzBio sentences presented at 60 dB SPL in quiet and in the presence of multi-talker babble (+10 dB SNR).

RESULTS

Relative to the clinical baseline program, speech perception scores with the four test programs decreased in both quiet and noisy listening conditions. In quiet, speech perception scores measured with the 30%M and 30%C programs were significantly (p < 0.001) poorer than the baseline program. No significant differences in speech perception scores were measured between the baseline and the 15%C or 15%M programs. In the noisy listening condition, speech perception scores were significantly poorer than the baseline program for the 15%C (p = 0.008), 30%C (p < 0.001), and 30%M (p < 0.001) programs. No significant differences in speech perception scores were obtained between the baseline and the 15%M program in the noisy listening condition. Speech perception scores measured with the 30%C program were significantly (p < 0.001) poorer than those with the 30%M program, suggesting that clipping was more detrimental than reducing electrical stimulation levels.

CONCLUSION

Small amounts (15%) of clipping can significantly decrease speech perception in the presence of background noise. Large amounts (30%) of both clipping and M-level reduction may lead to significantly poorer speech perception in quiet and in background noise. The decrease in speech perception scores can most likely be attributed to reduced volume and poorer spectro-temporal representation. Therefore, it is important to establish comfortably loud electrical stimulation levels without exceeding the compliance voltage to maximize cochlear implant outcomes.

Cochlear implantation in Ménière's disease: a systematic review of literature and pooled analysis

Objective: The aim of this study was to evaluate the effect of cochlear implantation (CI) in advanced Ménière's disease (MD).Design: The initial search on PubMed, EMBASE, and Cochrane databases yielded 171 articles; no language restriction was applied.Study sample: A total of 11 articles met the inclusion criteria and were included in this systematic review. Six articles provided patient-level data on improvement in speech recognition testing after CI.Results: The methodological quality of included studies was assessed by examining the study design, level of evidence, method of measurement and adequacy of outcome reporting. A random-effect model was fitted for calculating weighted means. Post-operative improvement in word recognition score (WCS) was 50.8% (95% confidence interval: 34.6-67.1%); general improvement of vestibular symptoms after CI was found in 67% of the pooled patients; when reported in the studies, quality of life (QoL) and tinnitus were also generally improved after CI.Conclusions: CI in advanced MD is a valid option providing good outcomes in terms of speech performances, regardless of the disease duration, uni- or bilaterality, age at implantation, previous therapeutic procedures and stage of activity of MD.

Cochlear Implantation in Ménière's Disease With and Without Labyrinthectomy

OBJECTIVE

To investigate outcomes of cochlear implantation (CI) in patients with Ménière's disease (MD) with and without surgical labyrinthectomy.

STUDY DESIGN

Retrospective study.

SETTING

Multiple tertiary referral centers.

SUBJECTS

Thirty one ears from 27 patients (17 men, 10 women, aged 42-84) with CI in ipsilateral MD ear.

INTERVENTION

CI in ears with intact labyrinths (Group 1), CI with simultaneous surgical labyrinthectomy (Group 2), and CI sequential to surgical labyrinthectomy (Group 3).

MAIN OUTCOME MEASURE

Within-subject improvement on Bamford Kowal Bench test or City University of New York open set sentence tests.

RESULTS

Majority of ears achieved excellent open-set speech recognition by 12 months post-CI, irrespective of intervention group. Preoperative details including patient age and sex, implant, MD and previous intervention, and audiological test results did not significantly affect outcomes. Patients with MD undergoing CI only may experience vestibular dysfunction which may cause long-term concerns. Incidental finding was noted of eight ears with fluctuating symptoms in ipsilateral ear during 12-month period post-CI, with five of eight ears showing objective fluctuating impedances and mapping.

CONCLUSION

CI in MD can yield good hearing outcomes in all three groups and this is possible even after a long delay after labyrinthectomy. Bilateral MD patients are complex and prospective quality of life (QoL) measures would be beneficial in being better able to manage the vestibular outcomes as well as the audiological ones.