Early cochlear implantation for children with single sided deafness

OBJECTIVES

Single-sided deafness (SSD) can have consequences for a child's language, educational, and social development. A cochlear implant (CI) is the only device which can restore true binaural hearing, yet they are only approved for children with (SSD) over the age of five in the United States. Reports on speech perception outcomes for children implanted at a younger age are limited. The present study aims to examine the effects of age at implantation, duration of deafness, hearing loss etiology, and presence of additional disabilities on device usage and speech perception outcomes.

METHODS

A retrospective chart review was used to examine demographics and speech perception outcomes for 18 children implanted at age five or younger.

RESULTS

Speech perception results were highly variable, with some children deriving significant benefit and others demonstrating no sound awareness through the implant alone. Age at implantation and duration of deafness did not have a clear impact on outcomes. Device usage was low in many children, often those with anatomical abnormalities such as a hypoplastic cochlear nerve. There are challenges to assessing speech perception in young children with SSD, leading to a lack of standardized outcome measures.

CONCLUSIONS

Early CI for children with SSD may improve speech perception, but benefit is not guaranteed. Candidacy evaluation should consider both medical and audiological factors, in addition to the degree of family support and realistic expectations. Caution is especially warranted in children with significant anatomical anomalies.

Influence of listening environment on usage patterns in cochlear implant patients with single-sided deafness

OBJECTIVE

To compare cochlear implant (CI) data logging of patients with single-sided deafness (SSD) and bilateral sensorineural hearing loss (biSNHL) in various acoustic environments and study the implications of data logging on auditory performance.

STUDY DESIGN

Retrospective case control study.

METHODS

Adult CI patients with SSD or biSNHL from 2010 to 2021 with usage data collected at 3-, 6-, and 12-months following device activation were identified. The CI listening environment was defined as speech in noise, speech in quiet, quiet, music or noise. Auditory performance was measured using the CNC word, AzBio sentence tests and the Tinnitus Handicap Index (THI).

RESULTS

60 adults with SSD or biSNHL were included. CI patients with biSNHL wore their devices more than those with SSD at 3-months post-activation (11.18 versus 8.97 hours/day, p = 0.04), though there were no significant differences at 6-12 months. Device usage was highest in the speech in quiet environment. In SSD CI users, there was a positive correlation (p = 0.03) between device use and CNC scores at 12-months and an improvement in THI scores at 12-months (p = 0.0004).

CONCLUSIONS

CI users with SSD and biSNHL have comparable duration of device usage at longer follow-up periods with greatest device usage recorded in speech in quiet environments.

Postoperative optimization of cochlear implantation for single sided deafness and asymmetric hearing loss: a systematic review

OBJECTIVE

Identify and evaluate the effectiveness of methods for improving postoperative cochlear implant (CI) hearing performance in subjects with single-sided deafness (SSD) and asymmetric hearing loss (AHL).

DATA SOURCES

Embase, PubMed, Scopus.

REVIEW METHODS

Systematic review and narrative synthesis. English language studies of adult CI recipients with SSD and AHL reporting a postoperative intervention and comparative audiometric data pertaining to speech in noise, speech in quiet and sound localization were included.

RESULTS

32 studies met criteria for full text review and 6 (n = 81) met final inclusion criteria. Interventions were categorized as: formal auditory training, programming techniques, or hardware optimization. Formal auditory training (n = 10) found no objective improvement in hearing outcomes. Experimental CI maps did not improve audiologic outcomes (n = 9). Programed CI signal delays to improve synchronization demonstrated improved sound localization (n = 12). Hardware optimization, including multidirectional (n = 29) and remote (n = 11) microphones, improved sound localization and speech in noise, respectively.

CONCLUSION

Few studies meeting inclusion criteria and small sample sizes highlight the need for further study. Formal auditory training did not appear to improve hearing outcomes. Programming techniques, such as CI signal delay, and hardware optimization, such as multidirectional and remote microphones, show promise to improve outcomes for SSD and AHL CI users.

Cochlear implantation in single-sided deafness: a single-center experience of 138 cases

OBJECTIVES

Assess the outcomes in patients who underwent cochlear implant (CI) for single-sided deafness (SSD).

METHODS

All patients affected by SSD who underwent CI at Gruppo Otologico, Piacenza, from October 2012 to May 2022 with at least 6 months of follow-up were selected in the study group. The analysis included subjective and objective measures performed pre-operative and up to 24 months after surgery. Hearing threshold on both sides was evaluated with a weighted four-frequency average (PTA [0.5 kHz + 1 kHz + 2 kHz + 4 kHz]/4) on pure tone audiometry and speech audiometry (Speech Discrimination Score, SDS). The Speech Spatial and Qualities of Hearing scale (SSQ Questionnaire) for binaural hearing benefits and sound localization, the Tinnitus Handicap Inventory Questionnaire (THI) and Dizziness Handicap Inventory Questionnaire (DHI) were used for subjective assessment.

RESULTS

Data from 138 patients, 69 males and 69 females, (mean age 49 years, range 17-77 years) underwent CI for SSD were examined. Single-sided hearing deprivation average before undergoing CI surgery was 2.5 years (range 3 months-35 years). There was a significant reduction of THI and DHI scores compared to pre-operative scores alongside a referred improvement in social, physical, and emotional well-being through the SSQ questionnaire.

CONCLUSIONS

To the best of our knowledge, this paper descried the largest cohort of SSD who underwent CI in a single institution. According to our findings CI in patients affected by SSD represents a valuable tool for an overall improvement of tinnitus and dizziness but also quality of life, after at least 6 months of follow-up. Further studies are desirable to improve rehabilitation pathways and possibly set new standards of care of this condition.

Brazilian Society of Otology task force - Vestibular Schwannoma ‒ evaluation and treatment

OBJECTIVE

To review the literature on the diagnosis and treatment of vestibular schwannoma.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on vestibular schwannoma were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) Diagnosis - audiologic, electrophysiologic tests, and imaging; (2) Treatment - wait and scan protocols, surgery, radiosurgery/radiotherapy, and systemic therapy.

CONCLUSIONS

Decision making in VS treatment has become more challenging. MRI can diagnose increasingly smaller tumors, which has disastrous consequences for the patients and their families. It is important to develop an individualized approach for each case, which highly depends on the experience of each surgical team.

Hearing rehabilitation for unilateral deafness using a cochlear implant: the influence of the subjective duration of deafness on speech intelligibility

BACKGROUND

For patients with single sided deafness (SSD) or severe asymmetric sensorineural hearing loss (ASHL), cochlear implantation remains the only solution to restore bilateral hearing capacity. Prognostically, the duration of hearing loss in terms of audiological outcome is not yet clear. Therefore, the aim of this study was to retrospectively investigate the influence of subjective deafness duration on postoperative speech perception after cochlear implantation for SSD as well as its impact on quality of life.

MATERIALS AND METHODS

The present study included a total of 36 adults aged 50.2 ± 15.5 years who underwent CI for SSD/ASHL at our clinic between 2010 and 2015. Patients were audiometrically assessed at 3 and 12-36 months postoperatively. Test results were correlated with self-reported duration of deafness. Quality of life was assessed by questionnaire.

RESULTS

Mean duration of deafness was 193.9 ± 185.7 months. The side-separated hearing threshold showed an averaged target range between 30 and 40 dB HL. Freiburg monosyllable test increased from 0% pre-operatively to 20% after 3 months (p = 0.001) and to 50% after 12-36 months (p = 0.002). There was a significant correlation between audiometric outcome and subjective deafness duration at 12-36 months postoperatively (r = - 0.564; p = 0.02) with a cutoff for open-set monosyllable recognition at a duration of deafness of greater than 408 months. Quality of life was significantly improved by CI.

CONCLUSIONS

CI implantation in unilaterally deafened patients provides objective and subjective benefits. Duration of deafness is unlikely to be an independent negative predictive factor and thus should not generally be considered as contraindication.

Disease Related Morbidity and Quality of Life Impairment in Patients with Single Sided Deafness

Patients with single sided-deafness (SSD) have hearing deficits amounting to a handicap to their everyday quality of life and are likely to suffer serious social challenges. There is a significant gap in the "disability" aspect of SSD in literature. The study was undertaken to compare the quality of life of SSD patients in various domains with normal hearing individuals. 51 patients of SSD with pure sensorineural hearing loss with impaired ear having a pure tone average of more than or equal to 70 dB was compared with 50 subjects with normal hearing sensitivity. Pure tone audiometric testing and the english version of Speech, Spatial and Qualities of Hearing Scale (SSQ) were used to enumerate subjective advantage. Total average SSQ score across domains in patients (6.6 ± 1.2) was significantly poorer in comparison to the control group (8.4 ± 0.9). Based on SSQ, patients with SSD experience hearing disability in comparison to the control group (p < 0.01). The ratings of all the items in the SSQ subdomains were higher in the reference group than in the patient group. Individuals with single sided-deafness experience significant auditory disability in all the three domains of speech, spatial & qualities of hearing. Therefore, these patients should be strongly counselled for currently available treatment options.

Cochlear Implantation for Unilateral Hearing Loss

Pediatric cochlear implantation for unilateral hearing loss is a new application of cochlear implants with Federal Drug Administration approval for this indication in 2019. The criteria for cochlear implant candidacy include evaluation of the etiology of hearing loss, the duration of deafness, child and family motivation, and the child's comorbidities. Studies have demonstrated significant improvements in speech perception in quiet and noise, sound localization, and speech and language development after implantation. Additional research is required to determine the best candidate and device for cochlear implantation.

How do patients decide on interventions for single sided deafness? A qualitative investigation of patient views

BACKGROUND

Single-sided deafness presents communication challenges for adults. There are a range of care options, including CROS hearing aids, available but little is known about patient preferences for these interventions.

OBJECTIVE

The objective of this study was to understand the viewpoints of patients making decisions about audiological interventions they use.

METHODS

A constructivist worldview using thematic analysis to undertake a constant comparative analysis of 8 semi-structured interviews.

SAMPLING

Participants were recruited from Portsmouth Hospitals University NHS Trust audiology service in England.

FINDINGS

The results of the study describe ongoing iterative judgements being made by participants, informed by their access to information, effectiveness of audiological interventions, stigma, barriers to accessing care, and constant cost-benefit analyses being made. The key factors involved in decision-making by individuals with Single-sided deafness (SSD) are discussed.

CONCLUSIONS

This study represents the first in-depth exploration of the individual's lifeworld related to which factors influence use of different audiological interventions by individuals with SSD. It highlights the complex and ongoing nature of how decisions are made by these individuals and identifies the need for greater information provision by clinicians, such as through use of a decision aid tool.

Expanding the indications for the bone anchored hearing system (BAHS) in patients with single sided deafness

PURPOSE

Provide data to support expansion of FDA indications for the Bone anchored hearing system (BAHS).

MATERIALS AND METHODS

This retrospective study in a tertiary otologic referral center included106 consecutive subjects who were implanted with a Bone Anchored Hearing System (BAHS) between January 2009 and January 2015 for single sided deafness. Subjects were divided into three groups by bone conduction pure tone average (PTA) of the better hearing ear: 0-20 dB (group 1), 21-40 dB (group 2) and 41-55 dB (group 3). All patients underwent BAHS implantation. Speech perception data (Hearing In Noise Test and Consonant-Nucleus-Consonant testing) was collected before and after surgical intervention. Patient-reported quality of life measures were obtained at least 6 months after activation. These included the Abbreviated Profile of Hearing Aid Benefit and Glasgow Benefit Inventory.

RESULTS

All three groups of subjects demonstrated statistically significant improvement in outcome measures following BAHS. Subject reported quality of life outcome measures demonstrated significant improvement in disability from hearing loss and in quality of life.

CONCLUSIONS

Patients with single sided deafness who have bone conduction thresholds worse than 20 dB in their contralateral ear are still able to benefit significantly from BAHS.

Long-term results of cochlear implantation in children with congenital single-sided deafness

Purpose

The purpose of this retrospective study was to investigate the outcome and critical age of cochlear implantation in congenital single-sided deafness (SSD).

Methods

11 children with congenital SSD were implanted with a cochlear implant (CI). Auditory performance was measured through the results of speech discrimination, subjective assessment by the Categories of auditory performance (CAP) score, the Speech, Spatial and Qualities scale questionnaire (SSQ) and the German version of the IOI-HA [Internationales Inventar zur Evaluation von Hörgeräten (IIEH, version for CI)].

Results

Long-term follow-up [median: 3 years and 5 months (3;5 years)] revealed that nine children use their CI (> 8 h/day) and two became nonusers. In children aged below 3;2 years at surgery, there was a substantial long-term increase in speech discrimination and subjective benefit. Children over 4;4 years of age at CI surgery improved partially in audiological/subjective measurements. Among children above 5 years, the SSQ score did not improve despite further slight improvement in speech discrimination long-term.

Conclusion

Our data suggest a critical age for CI surgery below 3 years in children with congenital SSD for successful hearing rehabilitation. It is mandatory to identify children with SSD as early as bilaterally deaf children.

Therapeutic challenges and clinical characteristics of single-sided deafness in children

INTRODUCTION

The clinical implications of single-sided deafness (SSD) in children has historically been underappreciated by patients and providers alike, despite a large body of literature on the wide-ranging neurocognitive, language, scholastic, and functional impairments that occur. Conventional amplification options are marked by variable results and frequent loss of follow-up.

METHODS

Retrospective case series for pediatric SSD from 2008 to 2018.

RESULTS

88 children with congenital SSD were identified. Seventeen (N = 17/88, 23.9%) passed their newborn hearing screen. Median age at first otolaryngology evaluation was 0.65 years (range 0.1-16.9 years). Most common etiologies included cochlear nerve deficiency (N = 39, CND, 44.3%), unknown (N = 30, 35.2%), inner ear malformation (N = 7, 8.0%), and congenital cytomegalovirus (N = 6, 6.8%). 32.5% of patients elected for continued observation only, followed by bone conduction hearing aid (27.7%), contralateral routing of sound aid (20.5%), conventional hearing aid (13.3%), or cochlear implant (6%). Lack of follow-up at ≥1 year was common (39.8%). Of those with device use data (N = 39), 84.7% reported either discontinued or <6 h of daily use.

CONCLUSIONS

Despite early diagnosis and evaluation, the pediatric SSD cohort is characterized by high rates of loss of follow-up and amplification discontinuation. Cochlear nerve deficiency is commonly seen in congenital SSD. Early specialist referral is critical for habilitation evaluation. Patients and caregivers should be educated on the significant implications of unilateral hearing loss.

Usefulness of cochlear implantation in children with single sided deafness

OBJECTIVES

Children with single sided deafness (SSD) show a poorer performance at school, which is attributable to reduced speech discrimination in noise, to reduced localization ability, and to a decreased power of concentration due to faster hearing exhaustion. Therefore, it is important to provide children with SSD with adequate hearing amplification to restore binaural hearing. This can only be achieved by provision with a cochlear implant (CI). But these treatment option in children with SSD is still under discussion. The aim of the present study is to evaluate audiological and clinical results in children with SSD following cochlear implantation. A special focus was placed on the duration of deafness before implantation and on the frequency of CI-use in everyday life.

METHODS

Seven children with SSD of different etiologies who were provided with a CI between 3 and 16 years of age were evaluated. Every child underwent multiple audiological tests before and after cochlear implantation. After cochlear implantation speech recognition tests in noise using the HSM (Hochmair, Schulz and Moser 1997) test and localization tests were performed. Furthermore, the frequency of implant use was evaluated.

RESULTS

Speech recognition in noise with CI compared to the unaided condition significantly improved in all children in different settings. Improvement of the localization ability measured by the root mean square error (RMSE) was shown in all children. All children are very satisfied with the decision to have undergone cochlear implantation and are all full-time users.

CONCLUSIONS

Cochlear implantation benefits speech recognition in noise and sound localization ability in children with SSD at different ages. All implanted children are full-time users regardless of age or duration of deafness before implantation.

Unilateral congenital hearing loss in children: Challenges and potentials

The estimated incidence of sensorineural hearing impairment (>40 dB HL) at birth is 1.86 per 1000 newborns in developed countries and 30-40% of these are unilateral. Profound sensorineural unilateral hearing impairment or single sided deafness (SSD) can be treated with a cochlear implant. However, this treatment is costly and invasive and unnecessary in the eyes of many. Very young children with SSD often do not exhibit language and cognitive delays and it is hard to imagine that neurocognitive skills will present difficulties with one good ear. In the current paper we review the most recent evidence on the consequences of unilateral hearing impairment for auditory and neurocognitive factors. While data of both adults and children are discussed, we focus on developmental factors, congenital deafness and a window of opportunity for intervention. We discuss which etiologies qualify for a cochlear implant and present our multi-center prospective study on cochlear implants in infants with one deaf ear. The large, state-of-the art body of research allows for evidence-based decisions regarding management of unilateral hearing loss in children.

Prevalence and etiology of sensorineural hearing loss in children with down syndrome: A cross-sectional study

BACKGROUND

The prevalence and causes of sensorineural hearing loss (SNHL) in children with Down syndrome (DS) are poorly delineated.

OBJECTIVE

To describe the prevalence, severity, laterality and underlying etiology of SNHL in a cohort of children with DS.

METHODS

A cross-sectional study was performed among all children with DS followed at the multidisciplinary Downteam of the Antwerp University Hospital. Patients' characteristics, risk factors for hearing loss, audiometric data and results of an etiological work-up were collected.

RESULTS

Among 291 patients in follow-up, 138 patients (47.4%) presented with hearing loss. In the majority this was caused by middle ear effusion and only 13 patients (4.5%) had sensorineural hearing loss, 7 boys and 6 girls with a mean age of 14.4 ± 7.4 years. Hearing loss was bilateral in 8 cases. Hearing loss severity was graded as mild in 38.5%, moderate in 30.8% and profound in 30.8% of the patients. An etiological work-up was completed in 9 children. Four patients presented with single sided deafness due to cochlear nerve deficiency. One patient had a genetic cause and in 2 patients the hearing loss was attributed to excessive noise exposure. The etiology of hearing loss was unknown in 6 patients.

CONCLUSION

Sensorineural hearing loss is uncommon in children with DS with a prevalence of 4.5%. Etiological work-up may allow identifying a specific underlying cause. Cochlear nerve deficiency was found in 4 children with DS and single sided deafness.

Contralateral suppression of human hearing sensitivity in single-sided deaf cochlear implant users

Cochlear implants (CIs) are being implanted in people with unilateral hearing loss because they can improve speech intelligibility and sound source localization. Though designed to restore the afferent auditory stimulation, the CI possibly restores some efferent effects. The present study aimed at investigating this possibility. Five single-sided deaf CI users with less than 30 dB hearing loss up to 4 kHz in their acoustic ear participated in the study. Absolute thresholds for their acoustic ears were measured for pure tones of 500 and 4000 Hz with durations of 10 and 200 ms in the presence and in the absence of contralateral broadband electrical stimulation (CBES) delivered with the CI. The electrical stimulus consisted of pulse trains (symmetric biphasic pulses with phase duration 36 μs) on all 16 electrodes sequentially stimulated at a rate of 843 Hz. Its intensity was set to sound as loud as broadband noise at 50 or 60 dB SPL in the acoustic ear. Thresholds were measured using a three-interval, three-alternative, forced-choice procedure with a two-down, one-up adaptive rule to estimate the level for 71% correct in the psychometric function. Thresholds measured without the CBES were lower for the longer than for the shorter tones, and the difference was larger at 500 than at 4000 Hz. CBES equivalent to 50 or 60 dB SPL caused significant threshold elevation only for short (10 ms) and low frequency (500 Hz) acoustic tones of 1.2 and 2.2 dB. These increases appear smaller than previously reported for normal hearing listeners in related experiments. These results support the notion that for single-sided deaf CI users, the CI modulates hearing in the acoustic ear. The possible mechanisms that may be contributing this effect are discussed.

Restoration of spatial hearing in adult cochlear implant users with single-sided deafness

In recent years, cochlear implants (CIs) have been provided in growing numbers to people with not only bilateral deafness but also to people with unilateral hearing loss, at times in order to alleviate tinnitus. This study presents audiological data from 15 adult participants (ages 48 ± 12 years) with single sided deafness. Results are presented from 9/15 adults, who received a CI (SSD-CI) in the deaf ear and were tested in Acoustic or Acoustic + CI hearing modes, and 6/15 adults who are planning to receive a CI, and were tested in the unilateral condition only. Testing included (1) audiometric measures of threshold, (2) speech understanding for CNC words and AzBIO sentences, (3) tinnitus handicap inventory, (4) sound localization with stationary sound sources, and (5) perceived auditory motion. Results showed that when listening to sentences in quiet, performance was excellent in the Acoustic and Acoustic + CI conditions. In noise, performance was similar between Acoustic and Acoustic + CI conditions in 4/6 participants tested, and slightly worse in the Acoustic + CI in 2/6 participants. In some cases, the CI provided reduced tinnitus handicap scores. When testing sound localization ability, the Acoustic + CI condition resulted in improved sound localization RMS error of 29.2° (SD: ±6.7°) compared to 56.6° (SD: ±16.5°) in the Acoustic-only condition. Preliminary results suggest that the perception of motion direction, whereby subjects are required to process and compare directional cues across multiple locations, is impaired when compared with that of normal hearing subjects.

Baha Attract: Our Experience

In this study, we have highlighted our experience with a new transcutaneous bone conduction hearing device, the Baha Attract System along with finer details on its surgical technique, some challenges faced intraoperatively and the surgical outcome. This study was carried out in our tertiary care hospital over the last 1 year. Our study included the first 4 patients, all of which were males; with a mean age of 13.25 years in whom the new Baha Attract System was used. The mean air-bone gap was 48 dB. Bone smoothening around the implant was needed in 2 patients. We did the switch-on after 6-12 weeks for all the patients where the programmed processor was applied with the help of a magnet at the implanted site. Our study results suggest that the Baha Attract System is promising for the patients with microtia-anotia having conductive or mixed hearing loss. These patients cannot be offered conventional air conduction hearing aids. Their hearing outcomes were comparable to percutaneous Baha systems.

Access to cochlear implants: Time to reflect

Cochlear implant (CI) intervention is expensive and accessed mainly by developed countries. The introduction of Universal Newborn Hearing Screening and funding via a public health service give children better access to CIs. However for adults large disparities exist between utilization and estimated prevalence. In the UK CI selection criteria are restrictive compared with many other countries. Improved audiological awareness and screening programmes for adults would improve access to hearing technologies that would improve health and quality of life. Hearing loss itself has significant medical and financial burdens on society and by investing in early intervention and using best technology this would mitigate some of the rising associated medical costs.

Induction of single-sided deafness in the newborn rat and its consequence for cochlear nucleus volume development

Aim of this study was to induce a single-sided deafness (SSD) in rats before hearing onset. Rats were operated at postnatal day 10 by approaching the tympanic cavity along a retroauricular path without manipulating ossicles or tympanic membrane. The ototoxic aminoglycoside neomycin was injected intracochlearly through the round window membrane on one side. When the animals have reached young adult stages, their hearing threshold was determined by their auditory brainstem response (ABR). Monaural deafening was considered successful when the hearing threshold was at least 95 dB above the threshold of the normal hearing ear. Growing up with one non-functional ear, rats developed a striking anatomical asymmetry of their cochlear nuclei (CN). The CN from age-matched normal hearing brains and from both sides of single-sided deaf brains were cut into series of frontal sections and their volumes calculated. No difference was detected between the volume of the normal hearing CN and the contralateral CN in SSD rats. By contrast, growth retardation was found for the ventral CN on the deaf side to result in a volume of only 57% compared to the normal hearing side. Marginal growth retardation was also observed for the dorsal CN on the deaf side. Thus, loss of sensory activation leads mainly, but not exclusively, to a reduction of tissue volume in the ventral CN of the deaf side, leaving the contralateral side apparently unaffected.

Interaural stimulation timing in single sided deaf cochlear implant users

The interaural time difference (ITD) is an important cue for the localization of sounds. ITD changes as little as 10 μs can be detected by the human auditory system. By provision of one ear with a cochlear implant (CI) ITD are altered due to the partial replacement of the peripheral auditory system. A hearing aid (HA), in contrast, does not replace but adds a processing delay component to the peripheral auditory system extending ITD. The aim of the present study was to quantify interaural stimulation timing between these different modalities to estimate the need for central auditory temporal compensation in single sided deaf CI users or bimodal CI/HA users. For this purpose, wave V latencies of auditory brainstem responses evoked either acoustically (ABR) or electrically via the CI (EABR) have been measured. The sum of delays consisting of CI signal processing measured in the MED-EL OPUS2 audio processor and EABR wave V latencies evoked on different intracochlear sites allowed an estimation of the entire CI channel-specific delay for MED-EL MAESTRO CI systems. We compared these values with ABR wave V latencies measured in the contralateral normal hearing or HA provided ear in different frequency bands. The results showed that EABR wave V latencies were consistently shorter than those evoked acoustically in the unaided normal hearing ear. Thus, artificial delays within the audio processor can be implemented to adjust interaural stimulation timing. The currently implemented group delays in the MED-EL CI system turned out to be reasonably similar to those of the unaided ear. For adjustment of CI and contralateral HA, in contrast, an adjustable additional across-frequency delay in the range of 1-11 ms implemented in the CI would be required. Especially for bimodal CI/HA users the adjustment of interaural stimulation timing may induce improved binaural hearing, reduced need for central auditory temporal compensation and increased acceptance of the CI/HA provision.

VALIDATION OF ACOUSTIC MODELS OF AUDITORY NEURAL PROSTHESES

Acoustic models have been used in numerous studies over the past thirty years to simulate the percepts elicited by auditory neural prostheses. In these acoustic models, incoming signals are processed the same way as in a cochlear implant speech processor. The percepts that would be caused by electrical stimulation in a real cochlear implant are simulated by modulating the amplitude of either noise bands or sinusoids. Despite their practical usefulness these acoustic models have never been convincingly validated. This study presents a tool to conduct such validation using subjects who have a cochlear implant in one ear and have near perfect hearing in the other ear, allowing for the first time a direct perceptual comparison of the output of acoustic models to the stimulation provided by a cochlear implant.

Surgical outcome of bone anchored hearing aid (baha) implant surgery: a 10 years experience

Bone anchored hearing aid (Baha) implant is an option for patient with canal atresia, single sided deafness(SSD) and chronically discharging ears despite treatments. This retrospective study was conducted from 2001 to 2011 to evaluate the surgical outcome of Baha implant surgery. Thirty-three patients were identified during this study period. Their age at implantation ranged from 5 to 40 years. Of 33 patients, 29 (87.9 %) patients had bilateral microtia and canal atresia, 3 (9.1 %) patients had unilateral microtia and canal atresia and 1 (3.0 %) patients have SSD following labyrinthitis. One patient (3.2 %) had major complication which is lost of implant due to failure of osseointegration. Soft tissue reactions were seen 7 patients (21.1 %). Of these 7 patients, 4 patients required 3-4 procedures as day care operation for excision of the skin overgrowth surrounding the abutment. Recurrent antibiotic treatment was required in 3 patients (9.7 %). None of our patient had history of intraoperative or peri-operative complication following Baha surgery. The commonest complications are local infection and inflammation at the implant site. None of our patient had history of intraoperative or peri-operative complication following Baha implant surgery.