Sustained-Release Triamcinolone Acetonide Hydrogels Reduce Hearing Threshold Shifts in a Model for Cochlear Implantation with Hearing Preservation
Introduction: In recent years, the preservation of residual hearing has become a major factor in patients undergoing cochlear implantation (CI). In studies attempting to pharmaceutically improve hearing preservation rates, glucocorticoids (GCs) applied perioperatively in many institutions have emerged as a promising treatment regimen. Although dexamethasone is most commonly used and has been applied successfully by various research groups, recently pharmacological properties have been reported to be relatively unsuitable for topical delivery to the inner ear. Consequently other glucocorticoids merit further evaluation. The aim of this study was therefore to evaluate the otoprotective effects of the topical application of a sustained-release triamcinolone acetonide (TAAC) hydrogel in CI with hearing preservation. Methods: Normal-hearing pigmented guinea pigs were randomized into a group receiving a single dose of a 6% TAAC poloxamer 407 hydrogel, a group receiving a 30% TAAC hydrogel and a control group. All hydrogel applications were performed 1 day prior to CI. After a cochleostomy was drilled, a specifically designed silicone electrode was inserted into the scala tympani for 5 mm. Frequency-specific compound action potentials of the auditory nerve (0.5–32 k
Hz) were measured pre- and directly postoperatively as well as on days 3, 7, 14, 21, and 28. Finally, temporal bones were harvested for histological evaluation. Results: Application of the TAAC hydrogels resulted in significantly reduced hearing threshold shifts in low, middle and high frequencies and improved spiral ganglion cell survival in the second turn of the cochlea. Outer hair cell numbers in the basal and second turn of the cochlea were slightly reduced after TAAC application. Conclusion: In summary, we were able to demonstrate functional benefits of a single preoperative application of a TAAC hydrogel in a guinea pig model for CI, which persisted until the end of the observational period, that is, 28 days after surgery.
Wide-Band Tympanometry Results during an Acute Episode of Ménière’s Disease
25-09-2019 – A Cakir Cetin,S Gurkan,G Kirkim,EA Guneri
Background: Wide-band tympanometry (WBT) was introduced as a beneficial diagnostic test for Ménière’s disease (MD) almost 15 years ago. However, an acute episode of MD has not been evaluated by using WBT yet. Objective: To investigate WBT findings in patients with MD during acute attacks. Method: Thirty definite MD patients with unilateral acute low-tone sensorineural hearing loss and aural fullness, and thirty age- and sex-matched control subjects were enrolled prospectively in a tertiary referral center. Ears were divided into three groups as follows: (1) affected ears of MD patients, (2) contralateral ears of MD patients, (3) control ears. Individuals underwent WBT. The resonance frequency (RF), mean absorbance value, mean low- and high-frequency absorbance values (LF-A and HF-A), and double peak width at 2 k
Hz of conductance tympanometry (2-k
Hz PW) were assessed. Results: Seventy percent in group 1, 66.7% in group 2, and 78.3% in group 3 demonstrated double peaks at 2 k
Hz. The mean 2-k
Hz PW values were 157.52 ± 79.19, 177.40 ± 79.14, and 139.64 ± 87.501 da
Pa for groups 1, 2, and 3, respectively. There were no significant differences between groups with respect to 2-k
Hz PW, RF, absorbance, LF-A, and HF-A. Conclusion: This was the first study that evaluated the effects of acute Ménière attacks on WBT findings. An acute Ménière attack was found to have no significant effect on the 2-k
Hz PW and other variables measured using WBT.
Concepts and Physiological Aspects of the Otolith Organ in Relation to Electrical Stimulation
25-09-2019 – IS Curthoys
Journal Article, Review
Background: This paper discusses some of the concepts and major physiological issues in developing a means of electrically stimulating the otolithic system, with the final goal being the electrical stimulation of the otoliths in human patients. It contrasts the challenges of electrical stimulation of the otolith organs as compared to stimulation of the semicircular canals. Electrical stimulation may consist of trains of short-duration pulses (e.g., 0.1 ms duration at 400 Hz) by selective electrodes on otolith maculae or otolithic afferents, or unselective maintained DC stimulation by large surface electrodes on the mastoids – surface galvanic stimulation. Summary: Recent anatomical and physiological results are summarized in order to introduce some of the unique issues in electrical stimulation of the otoliths. The first challenge is that each otolithic macula contains receptors with opposite polarization (opposing preferred directions of stimulation), unlike the uniform polarization of receptors in each semicircular canal crista. The puzzle is that in response to the one linear acceleration in the one macula, some otolithic afferents have an increased activation whereas others have decreased activation. Key Messages: At the vestibular nucleus this opposite receptor hair cell polarization and consequent opposite afferent input allow enhanced response to the one linear acceleration, via a “push-pull” neural mechanism in a manner analogous to the enhancement of semicircular canal responses to angular acceleration. Within each otolithic macula there is not just one uniform otolithic neural input to the brain – there are very distinctly different channels of otolithic neural inputs transferring the neural data to the brainstem. As a simplification these channels are characterized as the sustained and transient systems. Afferents in each system have different responses to stimulus onset and maintained stimulation and likely different projections, and most importantly different thresholds for activation by electrical stimulation and different adaptation rates to maintained stimulation. The implications of these differences are considered.
High Risk of Sudden Sensorineural Hearing Loss in Several Autoimmune Diseases according to a Population-Based National Sample Cohort Study
24-09-2019 – J Jeong,H Lim,K Lee,CE Hong,HS Choi
Objective: We investigated the risk of sudden sensorineural hearing loss (SSNHL) in patients with autoimmune diseases compared with a control group in a population-based study using a National Health Insurance Service National Sample Cohort data from Korea. Methods:We enrolled autoimmune-disease patients who were ≥20 years of age in 2006 into the autoimmune-disease group, and selected a control group with similar demographic characteristics. We tracked the 2 groups from 2006 to 2015 and compared the proportions of patients who developed SSNHL. Results: Of 13,250 patients in the autoimmune-disease group, 145 experienced an SSNHL event (1.09%). Of the 66,250 in the control group, 484 experienced an SSNHL event (0.73%). The SSNHL risk was significantly higher in the autoimmune-disease group than in the control group. SSNHL incidence was significantly higher among patients with antiphospholipid syndrome (APS), multiple sclerosis (MS), rheumatoid arthritis (RA), and connective-tissue diseases including Sjögren syndrome and Behçet disease. In detailed stratified analyses using reinforced additional diagnostic codes, only RA patients had a significantly higher SSNHL incidence than the control group. Conclusion: The association of several autoimmune diseases with SSNHL was evaluated in this large-scale, population-based, big-data study. The risk of SSNHL was significantly higher in patients with APS, MS, RA, and connective-tissue diseases including Sjögren syndrome and Behçet disease than in patients without autoimmune diseases. SSNHL, in particular, was significantly associated with RA according to detailed analyses using reinforced additional diagnostic codes.
Electrical Vestibular Stimulation in Humans: A Narrative Review
18-09-2019 – M Sluydts,I Curthoys,R Vanspauwen,BC Papsin,SL Cushing,A Ramos,A Ramos de Miguel,S Borkoski Barreiro,M Barbara,M Manrique,A Zarowski
Journal Article, Review
Background: In patients with bilateral vestibulopathy, the regular treatment options, such as medication, surgery, and/or vestibular rehabilitation, do not always suffice. Therefore, the focus in this field of vestibular research shifted to electrical vestibular stimulation (EVS) and the development of a system capable of artificially restoring the vestibular function. Key Message: Currently, three approaches are being investigated: vestibular co-stimulation with a cochlear implant (CI), EVS with a vestibular implant (VI), and galvanic vestibular stimulation (GVS). All three applications show promising results but due to conceptual differences and the experimental state, a consensus on which application is the most ideal for which type of patient is still missing. Summary: Vestibular co-stimulation with a CI is based on “spread of excitation,” which is a phenomenon that occurs when the currents from the CI spread to the surrounding structures and stimulate them. It has been shown that CI activation can indeed result in stimulation of the vestibular structures. Therefore, the question was raised whether vestibular co-stimulation can be functionally used in patients with bilateral vestibulopathy. A more direct vestibular stimulation method can be accomplished by implantation and activation of a VI. The concept of the VI is based on the technology and principles of the CI. Different VI prototypes are currently being evaluated regarding feasibility and functionality. So far, all of them were capable of activating different types of vestibular reflexes. A third stimulation method is GVS, which requires the use of surface electrodes instead of an implanted electrode array. However, as the currents are sent through the skull from one mastoid to the other, GVS is rather unspecific. It should be mentioned though, that the reported spread of excitation in both CI and VI use also seems to induce a more unspecific stimulation. Although all three applications of EVS were shown to be effective, it has yet to be defined which option is more desirable based on applicability and efficiency. It is possible and even likely that there is a place for all three approaches, given the diversity of the patient population who serves to gain from such technologies.
Rat Model of Ménière’s Attack: Intratympanic Injection of Potassium Chloride Produces Direction-Changing Spontaneous Nystagmus and Hearing Fluctuations
13-09-2019 – T Kamakura,T Kitahara,M Kondo,A Horii,Y Hanada,Y Takimoto,Y Ishida,Y Nakamura,T Imai,H Inohara,S Shimada
The major symptoms of Ménière’s disease are episodic vertigo, fluctuating hearing loss, and tinnitus. Direction-changing spontaneous nystagmus is a characteristic vestibular finding in Ménière’s disease. In the acute stage, spontaneous nystagmus beating to the affected side (irritative nystagmus) is often observed, while paralytic nystagmus beating to the healthy side is found in the chronic stage. This direction-changing nystagmus can be reproduced in guinea pigs by increasing the potassium ion concentration in the perilymph. The objectives of the present study were to examine the effects of increasing the potassium ion concentration of the rat perilymph on hearing and nystagmus. Under isoflurane anesthesia, 22 rats received intratympanic injection of different concentrations of potassium chloride (KCl) solution or distilled water: groups 1, 2, 3, and 4 received saturated (3.4 M) KCl solution, 2 M KCl, 1 M KCl, and distilled water, respectively. The nystagmus direction and number per 15 s were monitored for 150 min. In the other 8 rats, hearing was monitored 30 min and 20 h after intratympanic injection of 2 M KCl (group 5) or distilled water (group 6) using the auditory brainstem responses. Rats in groups 1 and 2 showed spontaneous irritative nystagmus beating to the affected ear followed by paralytic nystagmus beating to the contralateral side. In group 3, irritative nystagmus occurred but paralytic nystagmus was rarely observed. Rats in group 4 showed no nystagmus. Rats in group 5 showed significant hearing impairment 30 min after KCl injection that recovered 20 h later. Control animals in group 6 showed no significant changes in hearing. The reversible hearing impairment with direction-changing spontaneous nystagmus induced by potassium injection into the tympanic cavity in rats was quite similar to that observed in acute Ménière’s attacks. This rat model could be used for basic research investigating the pathophysiological mechanisms underlying Ménière’s attacks.
Data Logging Evidence of Cochlear Implant Use in Single-Sided and Bilateral Deafness
11-09-2019 – AK Rauch,S Kagermann,T Wesarg,TF Jakob,A Aschendorff,G Ihorst,I Speck,S Arndt
Purpose: This study analyses data logs in order to investigate the usage pattern of cochlear implant (CI) recipients with single-sided deafness (SSD-CI) and bilaterally deaf, uni- or bilaterally implanted CI recipients (Uni-CI and Bil-CI). Data logging is available from SCAN, an automated auditory scene classifier which categorizes auditory input into 6 listening environments. Methods: CI usage data were retrospectively available from data logs of 206 CI recipients using the Nucleus 6 system obtained between January 2013 and June 2015. For all recipients, we analysed time on air and time spent in the listening environments. For statistical analysis, we matched the CI recipients according to age and duration of CI experience and classified them into 4 age groups. Results: SSD-CI showed a similar time on air compared to Uni- and Bil-CI. Usage behaviour of SSD-CI was comparable to Uni- and Bil-CI regarding exposure to music, speech in quiet and speech in noise. With increasing age, exposure to quiet increased and exposure to music decreased across all CI recipient groups in relation to time on air. Conclusion: In total, the CI usage pattern of SSD-CI is comparable for the majority of listening environments and age groups to that of Uni- and Bil-CI. The results of our study show that SSD-CI benefit equally from CI implantation.
Early Assessment of Vestibular Function after Unilateral Cochlear Implant Surgery
10-09-2019 – M Barbara,R Talamonti,AT Benincasa,S Tarentini,C Filippi,E Covelli,S Monini
Introduction: Cochlear implantation (CI) has been reported to negatively affect vestibular function. The study of vestibular function has variably been conducted using different types of diagnostic tools. The combined use of modern, rapidly performing diagnostic tools could prove useful for standardization of the evaluation protocol. Methods: In a group of 28 subjects undergoing CI, the video head impulse test (v
HIT), the cervical vestibular evoked myogenic potentials (cVEMP) and the short form of the Dizziness Handicap Inventory (DHI) questionnaire were investigated preoperatively and postoperatively (implant on and off) in both the implanted and the contralateral, nonimplanted ear. All surgeries were performed with a round window approach (RWA), except for 3 otosclerosis cases in which the extended RWA (e
RWA) was used. Results: The v
HIT of the lateral semicircular canal showed preoperative vestibular involvement in nearly 50% of the cases, while the 3 canals were contemporarily affected in only 14% of the cases. In all the hypofunctional subjects, cVEMP were absent. A low VOR gain in all of the investigated superior semicircular canals was found in 4 subjects (14%). In those subjects (21.7%) in whom cVEMP were preoperatively present and normal on the operated side, the absence of a response was postoperatively recorded. Discussion/Conclusion: The vestibular protocol applied in this study was found to be appropriate for distinguishing between the CI-operated ear and the nonoperated ear. In this regard, cVEMP was found to be more sensitive than v
HIT for revealing a vestibular sufferance after CI, though without statistical significance. Finally, the use of RWA surgery apparently did not reduce the occurrence of signs of vestibular impairment.
Outcomes after Application of Active Bone Conducting Implants
09-09-2019 – E Koro,M Werner
Background: A bone conducting implant is a treatment option for individuals with conductive or mixed hearing loss (CHL, MHL) who do not tolerate regular hearing aids, and for individuals with single-sided deafness (SSD). An active bone conducting implant (ABCI) was introduced in 2012 with indication in CHL, MHL, and SSD, and it is still the only ABCI available. With complete implantation of the active transducer and consequent intact skin, a decrease in infections, skin overgrowth, and implant losses, all common disadvantages with earlier passive bone conducting implants, could be expected. Our Ear, Nose and Throat Department, a secondary care center for otosurgery that covers a population of approximately 365,000 inhabitants, was approved to implant ABCIs in 2012. Objectives: Our aim was to conduct an evaluation of audiological and subjective outcomes after ABCIs. Method: A cohort study with retrospective and prospective data collection was performed.
The first 20 consecutive patients operated with an ABCI were asked for informed consent. The main outcome measures werepure tone and speech audiometry and the Glasgow Benefit Inventory (GBI). Results: Seventeen patients accepted to participate and 15 were able to complete all parts. Six patients had CHL or MHL. In this group the pure tone audiometry tests are comparable with an average functional hearing gain of 29.8 d
B HL. With bilateral hearing, the mean Word Recognition Score (WRS) in noise was 35.7% unaided and 62.7% aided. Ten patients had the indication SSD. With the hearing ear blocked, the pure tone average was #x3e;101 d
B HL, compared to 29.3 d
B HL in sound field aided. With bilateral hearing, the mean WRS in noise was 59.7% unaided and 72.8% aided. The mean of the total GBI score was 42.1 in the group with CHL or MHL and 20.6 in the group with SSD. Conclusions: The patients benefit from their implants in terms of quality of life, and there is a substantial hearing gain from the implant for patients with conductive or MHL. Patients with SSD benefit less from the implant than other diagnoses but the positive outcomes are comparable to other options for this group.
Genetics of Hereditary Hearing Loss in the Middle East: A Systematic Review of the Carrier Frequency of the GJB2 Mutation (35delG)
05-09-2019 – M Koohiyan
Background and Objectives: Mutations in the GJB2 gene are a major cause of hearing loss in many populations. A single mutation of this gene (c.35del
G) accounts for approximately 70% of mutations in Caucasians with a carrier frequency of 2–4% in Europe. This study aims to determine the rate of c.35del
G carrier frequency in the Middle East. Method: A systematic literature review of the PubMed, Google Scholar, Web of Science, and Science Direct databases was conducted for articles published before March 2019. The primary data of eligible studies including the number of samples, carrier frequency and so on were extracted. Results: Fourteen studies that involved 5,200 random controls from 15 populations of the Middle East were included and analyzed for the carrier frequency. The overall c.35del
G carrier frequency was found to be 1.38% in the studied populations which is significantly lower than that identified in European populations, and also a west-to-east Middle Eastern gradient in the carrier frequency of c.35del
G is suggested. Conclusion: This study shows the importance of establishing prevalence, based on the local population, for screening and diagnostic programs of live births.