A systematic review of the effectiveness and cost-effectiveness of bilateral multichannel cochlear implants in adults with severe-to-profound hearing loss

Simultaneous Bilateral Cochlear Implantation in Adults

The objective of this study is to review our experience with simultaneous bilateral cochlear implantation (BiCI) in adults, and assess its feasibility. This could shorten the time required to regain binaural hearing, prevent social isolation, and potentially eliminate the need for hearing aids, as seen with sequential BiCI. A retrospective study was conducted involving adult patients who received simultaneous BiCI at our center between 2010 and 2023. The feasibility of simultaneous BiCI was assessed through postoperative clinical evaluations, outpatient visits, discharge status, and the acceptance of device fitting. Twenty-seven patients underwent simultaneous BiCIs. Their mean age was 37 years, comprising 59.3% males and 40.7% females. Out of the included patients, 51.9% had childhood-onset hearing loss, while 29.6% developed hearing loss later in life. Causes of hearing loss included meningitis 7.4%, trauma 11.1%, non-specific high-grade fever 11.1%, and Brucellosis infection 3.7%. Labyrinthine ossificans (LO) was present in 7.4%, and retrofenestral otospongiosis in 3.7%. The post-operative period and initial outpatient visit were uneventful for 88.8% and 81.5% of patients, respectively. Intraoperative complications were absent in 96.2% of cases. Simultaneous BiCI is feasible in adults without major intraoperative complications or troublesome recovery periods, offering potential benefits by reducing the number of surgeries and hospital admissions compared to the sequential method.

Comparison of Outcomes in Unilateral and Bilateral Pediatric Cochlear Implants: Our Experience

The aim of our study is to compare the outcomes in unilateral and bilateral cochlear implants in pediatric age and also between simultaneous and sequential cochlear implant surgery. This retrospective study was carried out with 83 children aged between 12 months to 2.5 years which included 41 children with bilateral Cochlear implants and 42 with unilateral implants. Out of these 41 children, 21 were simultaneous and 20 were sequential cochlear implant. All the children were operated at civil hospital Gandhinagar, Gujarat, India. CAP, SIR, localization, traffic noise and speech in noise scores were assessed at regular intervals over the period of 4 years. Also the drug administration time, surgical time, operating room time were assessed for simultaneous and sequential cochlear implant surgery. Children with bilateral simultaneous implants fared significantly better with CAP, SIR, localization, speech noise and traffic noise scores than sequential bilateral implants and unilateral implants with a significant difference of means t tests between the two groups. Simultaneous cochlear implant surgery is associated with reduced surgical time, operating room time, it shortens the total in patient stay. There is less of drug administration and bilateral ones are stimulated simultaneously. Bilateral cochlear implants perform better with respect to auditory perception skills and spontaneous speech when compared with unilateral implants, but simultaneous surgery is better and safe option for pediatric cochlear implantation.

Oscillation Characteristics of an Artificial Cochlear Sensory Epithelium Optimized for a Micrometer-Scale Curved Structure

Based on the modern microelectromechanical systems technology, we present a revolutionary miniaturized artificial cochlear sensory epithelium for future implantation tests on guinea pigs. The device was curved to fit the spiral structure of the cochlea and miniaturized to a maximum dimension of <1 mm to be implanted in the cochlea. First, the effect of the curved configuration on the oscillation characteristics of a trapezoidal membrane was evaluated using the relatively larger devices, which had a trapezoidal and a comparable curved shape designed for high-precision in vitro measurements. Both experimental and numerical analyses were used to determine the resonance frequencies and positions, and multiple oscillation modes were clearly observed. Because the maximum oscillation amplitude positions, i.e., the resonance positions, differed depending on the resonance frequencies in both trapezoidal and curved membrane devices, the sound frequency was determined based on the resonance position, thus reproducing the frequency selectivity of the basilar membrane in the organ of Corti. Furthermore, the resonance frequencies and positions of these two devices with different configurations were determined to be quantitatively consistent and similar in terms of mechanical dynamics. This result shows that despite a curved angle of 50−60°, the effect of the curved shape on oscillation characteristics was negligible. Second, the nanometer-scale oscillation of the miniaturized device was successfully measured, and the local resonance frequency in air was varied from 157 to 277 kHz using an experimental system that could measure the amplitude distribution in a two-dimensional (2D) plane with a high accuracy and reproducibility at a high speed. The miniaturized device developed in this study was shown to have frequency selectivity, and when the device was implanted in the cochlea, it was expected to discriminate frequencies in the same manner as the basilar membrane in the biological system. This study established methods for fabricating and evaluating the miniaturized device, and the proposed miniaturized device in a curved shape demonstrated the feasibility of next-generation cochlear implants.

Improvements in Hearing and in Quality of Life after Sequential Bilateral Cochlear Implantation in a Consecutive Sample of Adult Patients with Severe-to-Profound Hearing Loss

Bilateral cochlear implantation is increasing worldwide. In adults, bilateral cochlear implants (BICI) are often performed sequentially with a time delay between the first (CI1) and the second (CI2) implant. The benefits of BICI have been reported for well over a decade. This study aimed at investigating these benefits for a consecutive sample of adult patients. Improvements in speech-in-noise recognition after CI2 were followed up longitudinally for 12 months with the internationally comparable Finnish matrix sentence test. The test scores were statistically significantly better for BICI than for either CI alone in all assessments during the 12-month period. At the end of the follow-up period, the bilateral benefit for co-located speech and noise was 1.4 dB over CI1 and 1.7 dB over CI2, and when the noise was moved from the front to 90 degrees on the side, spatial release from masking amounted to an improvement of 2.5 dB in signal-to-noise ratio. To assess subjective improvements in hearing and in quality of life, two questionnaires were used. Both questionnaires revealed statistically significant improvements due to CI2 and BICI. The association between speech recognition in noise and background factors (duration of hearing loss/deafness, time between implants) or subjective improvements was markedly smaller than what has been previously reported on sequential BICI in adults. Despite the relatively heterogeneous sample, BICI improved hearing and quality of life.

Evidence gaps in economic analyses of hearing healthcare: A systematic review

BACKGROUND

Hearing loss is a common and costly medical condition. This systematic review sought to identify evidence gaps in published model-based economic analyses addressing hearing loss to inform model development for an ongoing Lancet Commission.

METHODS

We searched the published literature through 14 June 2020 and our inclusion criteria included decision model-based cost-effectiveness analyses that addressed diagnosis, treatment, or prevention of hearing loss. Two investigators screened articles for inclusion at the title, abstract, and full-text levels. Data were abstracted and the studies were assessed for the qualities of model structure, data assumptions, and reporting using a previously published quality scale.

FINDINGS

Of 1437 articles identified by our search, 117 unique studies met the inclusion criteria. Most of these model-based analyses were set in high-income countries (n = 96, 82%). The evaluated interventions were hearing screening (n = 35, 30%), cochlear implantation (n = 34, 29%), hearing aid use (n = 28, 24%), vaccination (n = 22, 19%), and other interventions (n = 29, 25%); some studies included multiple interventions. Eighty-six studies reported the main outcome in quality-adjusted or disability-adjusted life-years, 24 of which derived their own utility values. The majority of the studies used decision tree (n = 72, 62%) or Markov (n = 41, 35%) models. Forty-one studies (35%) incorporated indirect economic effects. The median quality rating was 92/100 (IQR:72-100).

INTERPRETATION

The review identified a large body of literature exploring the economic efficiency of hearing healthcare interventions. However, gaps in evidence remain in evaluation of hearing healthcare in low- and middle-income countries, as well as in investigating interventions across the lifespan. Additionally, considerable uncertainty remains around productivity benefits of hearing healthcare interventions as well as utility values for hearing-assisted health states. Future economic evaluations could address these limitations.

FUNDING

NCATS 3UL1-TR002553-03S3.

A Preliminary Prototype High-Speed Feedback Control of an Artificial Cochlear Sensory Epithelium Mimicking Function of Outer Hair Cells

A novel feedback control technique for the local oscillation amplitude in an artificial cochlear sensory epithelium that mimics the functions of the outer hair cells in the cochlea is successfully developed and can be implemented with a control time on the order of hundreds of milliseconds. The prototype artificial cochlear sensory epithelium was improved from that developed in our previous study to enable the instantaneous determination of the local resonance position based on the electrical output from a bimorph piezoelectric membrane. The device contains local patterned electrodes deposited with micro electro mechanical system (MEMS) technology that is used to detect the electrical output and oscillate the device by applying local electrical stimuli. The main feature of the present feedback control system is the principle that the resonance position is recognized by simultaneously measuring the local electrical outputs of all of the electrodes and comparing their magnitudes, which drastically reduces the feedback control time. In this way, it takes 0.8 s to control the local oscillation of the device, representing the speed of control with the order of one hundred times relative to that in the previous study using the mechanical automatic stage to scan the oscillation amplitude at each electrode. Furthermore, the intrinsic difficulties in the experiment such as the electrical measurement against the electromagnetic noise, adhesion of materials, and fatigue failure mechanism of the oscillation system are also shown and discussed in detail based on the many scientific aspects. The basic knowledge of the MEMS fabrication and the experimental measurement would provide useful suggestions for future research. The proposed preliminary prototype high-speed feedback control can aid in the future development of fully implantable cochlear implants with a wider dynamic range.

Methodological Quality of Systematic Reviews and Meta-analyses Published in High-Impact Otolaryngology Journals

OBJECTIVE

To assess the methodological quality of intervention-focused systematic reviews (SRs) and meta-analyses (MAs) published in high-impact otolaryngology journals.

DATA SOURCES

Ovid Medline, Embase, and Cochrane Library.

REVIEW METHODS

A comprehensive search was performed for SR and MA citations from 2012 to 2017 in the 10 highest impact factor otolaryngology journals. Abstracts were screened to identify published manuscripts in which the authors indicated clearly that they were performing an SR or MA. Applying a modified typology of reviews, 4 reviewers characterized the review type as SR, MA, or another review type. A simplified version of the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews 2) tool was used to assess the reporting and methodological quality of the SRs and MAs that were focused on interventions.

RESULTS

Search and abstract screening generated 499 manuscripts that identified themselves as performing an SR or MA. A substantial number (85/499, 17%) were review types other than SRs or MAs, including 34 (7%) that were literature reviews. In total, 236 SRs and MAs focused on interventions. Over 50% of these SRs and MAs had weaknesses in at least 3 of the 16 items in the AMSTAR 2, and over 40% had weaknesses in at least 2 of the 7 critical domains. Ninety-nine percent of SRs and MAs provided critically low confidence in the results of the reviews.

CONCLUSION

Intervention-focused SRs and MAs published in high-impact otolaryngology journals have important methodological limitations that diminish confidence in the results of these reviews.

General Health Quality of Life Instruments Underestimate the Impact of Bilateral Cochlear Implantation

OBJECTIVE

To determine the extent to which bilateral cochlear implantation increases patient-reported benefit as compared with unilateral implantation and no implantation.

DATA SOURCES

PubMed, Scopus, CINAHL, and Cochrane databases searches were performed using the keywords ("Cochlear Implant" or "Cochlear Implantation") and ("bilateral").

STUDY SELECTION

Studies assessing hearing/CI-specific (CI) and general-health-related (HR) quality of life (QOL) in adult patients after bilateral cochlear implantation were included.

DATA EXTRACTION

Of the 31 articles meeting criteria, usable QOL data were available for 16 articles (n = 355 bilateral CI recipients).

DATA SYNTHESIS

Standardized mean difference (Δ) for each measure and weighted effects were determined. Meta-analysis was performed for all QOL measures and also independently for hearing/CI-specific QOL and HRQOL.

CONCLUSION

When measured using hearing/CI-specific QOL instruments, patients reported very large improvements in QOL comparing before cochlear implantation to bilateral CI (Δ=2.07 [1.76-2.38]) and medium improvements comparing unilateral CI to bilateral CI (Δ=0.51 [0.32- 0.71]). Utilization of parallel versus crossover study design did not impact QOL outcomes (χ = 0.512, p = 0.47). No detectable improvements were observed in either CI transition when using HRQOL instruments (no CI to bilateral CI: Δ=0.40 [-0.02 to 0.81]; unilateral CI to bilateral CI: Δ=0.22 [-0.02 to 0.46]).The universal nature of HRQOL instruments may render them insensitive to the medium to large QOL improvements reported by patients using hearing/CI-specific QOL instruments. Given that HRQOL instruments are used to determine the economic benefit of health interventions, these measurement differences suggest that the health economic value of bilateral cochlear implantation has been underestimated.

Benefits of a contralateral routing of signal device for unilateral Naída CI cochlear implant recipients

PURPOSE

Many bilaterally deaf adults are only able to receive one cochlear implant (CI), resulting in suboptimal listening performance, especially in challenging listening environments. Adding a contralateral routing of signal (CROS) device to a unilateral CI is one possibility to alleviate these challenges. This study examined the benefit of such a CROS device.

METHODS

Thirteen adult subjects with at least 6 months of CI use, and no or limited benefit of a hearing instrument in the contralateral ear were included in the study. The perceived benefit of a CROS device in everyday listening environments was evaluated up to 1 year after initial fitting using several questionnaires. Speech intelligibility performance was determined using the French matrix sentence test in quiet and in two speech-in-noise setups and was followed for 3 months after CROS fitting.

RESULTS

Subjects indicated high satisfaction with the practical usability of the CROS device and long-term device retention was high. Perceived benefits in everyday listening environments were reported. Formal speech intelligibility tests revealed statistically significant median improvements of 6.93 dB SPL (Wilcoxon Z = 2.380, p = 0.017) in quiet and up to 8.00 dB SNR (Wilcoxon Z = 2.366, p = 0.018) in noise. These benefits were accessible immediately without a need for prolonged acclimatization.

CONCLUSIONS

Subjective satisfaction and device retention as well as speech intelligibility benefits in quiet and in noise prove the CROS device to be a valuable addition to a unilateral CI in cases of bilateral deafness where bilateral implantation is not an option.

No Difference in Behavioral and Self-Reported Outcomes for Simultaneous and Sequential Bilateral Cochlear Implantation: Evidence From a Multicenter Randomized Controlled Trial

Objective: The primary aim of this study was to longitudinally compare the behavioral and self-reported outcomes of simultaneous bilateral cochlear implantation (simBiCI) and sequential BiCI (seqBiCI) in adults with severe-to-profound postlingual sensorineural hearing loss. Design: This study is a multicenter randomized controlled trial with a 4-year follow-up period after the first moment of implantation. Participants were allocated by randomization to receive bilateral cochlear implants (CIs) either, simultaneously (simBiCI group) or sequentially with an inter-implant interval of 2 years (UCI/seqBiCI group). All sequential patients where encouraged to use their hearing aid on the non-implanted ear over of the first 2 years. Patients were followed-up on an annual basis. The primary outcome was speech perception in noise coming from a source directly in front of the patient. Other behavioral outcome measures were speech intelligibility-in-noise from spatially separated sources, localization and speech perception in quiet. Self-reported outcome measures encompassed questionnaires on quality of life, quality of hearing and tinnitus. All outcome measures were analyzed longitudinally using a linear or logistic regression analysis with an autoregressive residual covariance matrix (generalized estimating equations type). Results: Nineteen participants were randomly allocated to the simBiCI group and 19 participants to the UCI/seqBiCI group. Three participants in the UCI/seqBiCI group did not proceed with their second implantation and were therefore unavailable for follow-up. Both study groups performed equally well on speech perception in noise from a source directly in front of the patient longitudinally. During all 4 years of follow-up the UCI/seqBiCI group performed significantly worse compared to the simBiCI group on spatial speech perception in noise in the best performance situation (8.70 dB [3.96 - 13.44], p < 0.001) and localization abilities (largest difference 60 degrees configuration: -44.45% [-52.15 - -36.74], p < 0.0001). Furthermore, during all years of follow-up, the UCI/seqBiCI group performed significantly worse on quality of hearing and quality of life questionnaires. The years of unilateral CI use were the reason for the inferior results in the UCI/SeqBiCI group. One year after receiving CI2, the UCI/seqBiCI group performance did not statistically differ from the performance of the simBiCI group on all these outcomes. Furthermore, no longitudinal differences were seen in tinnitus burden prevalence between groups. Finally, the complications that occurred during this trial were infection, dysfunction of CI, facial nerve palsy, tinnitus and vertigo. Conclusion: This randomized controlled trial on bilaterally severely hearing impaired participants found a significantly worse longitudinal performance of UCI/seqBiCI compared to simBiCI on multiple behavioral and self-reported outcomes regarding speech perception in noise and localization abilities. This difference is associated with the inferior performance of the UCI/seqBiCI participants during the years of unilateral CI use. After receiving the second CI however, the performance of the UCI/seqBiCI group did not significantly differ from the simBiCI group. Trial Registration: Dutch Trial Register NTR1722.

PVDF-Based Piezoelectric Microphone for Sound Detection Inside the Cochlea: Toward Totally Implantable Cochlear Implants

We report the fabrication and characterization of a prototype polyvinylidene fluoride polymer-based implantable microphone for detecting sound inside gerbil and human cochleae. With the current configuration and amplification, the signal-to-noise ratios were sufficiently high for normally occurring sound pressures and frequencies (ear canal pressures >50-60 dB SPL and 0.1-10 kHz), though 10 to 20 dB poorer than for some hearing aid microphones. These results demonstrate the feasibility of the prototype devices as implantable microphones for the development of totally implantable cochlear implants. For patients, this will improve sound reception by utilizing the outer ear and will improve the use of cochlear implants.

Objective and Subjective Measures of Simultaneous vs Sequential Bilateral Cochlear Implants in Adults: A Randomized Clinical Trial

Importance

To date, no randomized clinical trial on the comparison between simultaneous and sequential bilateral cochlear implants (BiCIs) has been performed.

Objective

To investigate the hearing capabilities and the self-reported benefits of simultaneous BiCIs compared with those of sequential BiCIs.

Design, Setting, and Participants

A multicenter randomized clinical trial was conducted between January 12, 2010, and September 2, 2012, at 5 tertiary referral centers among 40 participants eligible for BiCIs. Main inclusion criteria were postlingual severe to profound hearing loss, age 18 to 70 years, and a maximum duration of 10 years without hearing aid use in both ears. Data analysis was conducted from May 24 to June 12, 2016.

Interventions

The simultaneous BiCI group received 2 cochlear implants during 1 surgical procedure. The sequential BiCI group received 2 cochlear implants with an interval of 2 years between implants.

Main Outcomes and Measures

First, the results 1 year after receiving simultaneous BiCIs were compared with the results 1 year after receiving sequential BiCIs. Second, the results of 3 years of follow-up for both groups were compared separately. The primary outcome measure was speech intelligibility in noise from straight ahead. Secondary outcome measures were speech intelligibility in noise from spatially separated sources, speech intelligibility in silence, localization capabilities, and self-reported benefits assessed with various hearing and quality of life questionnaires.

Results

Nineteen participants were randomized to receive simultaneous BiCIs (11 women and 8 men; median age, 52 years [interquartile range, 36-63 years]), and another 19 participants were randomized to undergo sequential BiCIs (8 women and 11 men; median age, 54 years [interquartile range, 43-64 years]). Three patients did not receive a second cochlear implant and were unavailable for follow-up. Comparable results were found 1 year after simultaneous or sequential BiCIs for speech intelligibility in noise from straight ahead (difference, 0.9 dB [95% CI, -3.1 to 4.4 dB]) and all secondary outcome measures except for localization with a 30° angle between loudspeakers (difference, -10% [95% CI, -20.1% to 0.0%]). In the sequential BiCI group, all participants performed significantly better after the BiCIs on speech intelligibility in noise from spatially separated sources and on all localization tests, which was consistent with most of the participants' self-reported hearing capabilities. Speech intelligibility-in-noise results improved in the simultaneous BiCI group up to 3 years following the BiCIs.

Conclusions and Relevance

This study shows comparable objective and subjective hearing results 1 year after receiving simultaneous BiCIs and sequential BiCIs with an interval of 2 years between implants. It also shows a significant benefit of sequential BiCIs over a unilateral cochlear implant. Until 3 years after receiving simultaneous BiCIs, speech intelligibility in noise significantly improved compared with previous years.

Trial Registration

trialregister.nl Identifier: NTR1722.

Cost-effectiveness of pediatric bilateral cochlear implantation in Spain

OBJECTIVES/HYPOTHESIS

To determine the incremental cost-effectiveness of bilateral versus unilateral cochlear implantation for 1-year-old children suffering from bilateral sensorineural severe to profound hearing loss from the perspective of the Spanish public health system.

STUDY DESIGN

Cost-utility analysis.

METHODS

We conducted a general-population survey to estimate the quality-of-life increase contributed by the second implant. We built a Markov influence diagram and evaluated it for a life-long time horizon with a 3% discount rate in the base case.

RESULTS

The incremental cost-effectiveness ratio of simultaneous bilateral implantation with respect to unilateral implantation for 1-year-old children with severe to profound deafness is €10,323 per quality-adjusted life year (QALY). For sequential bilateral implantation, it rises to €11,733/QALY. Both options are cost-effective for the Spanish health system, whose willingness to pay is estimated at around €30,000/QALY. The probabilistic sensitivity analysis shows that the probability of bilateral implantation being cost-effective reaches 100% for that cost-effectiveness threshold.

CONCLUSIONS

Bilateral implantation is clearly cost-effective for the population considered. If possible, it should be done simultaneously (i.e., in one surgical operation), because it is as safe and effective as sequential implantation, and saves costs for the system and for users and their families. Sequential implantation is also cost-effective for children who have received the first implant recently, but it is difficult to determine when it ceases to be so because of the lack of detailed data. These results are specific for Spain, but the model can easily be adapted to other countries.

LEVEL OF EVIDENCE

2C. Laryngoscope, 127:2866-2872, 2017.

Trials of a Contralateral Hearing Aid After Long-Term Unilateral Cochlear Implant Use in Early-Onset Deafness

PURPOSE

The purpose of this study was to evaluate the practicability of binaural hearing by adding a contralateral hearing aid (HA) after long-term cochlear implant (CI) use in prelingually deaf adults.

METHOD

Five individuals with 1 CI volunteered for a 3-week bimodal (CI + HA) trial. HA gain was set low until sound was tolerable, then increased as listeners acclimated. Participants logged their daily listening experiences and were closely monitored by the audiologist. Measures included pre- and posttrial consonant-nucleus-consonant (CNC) word and phoneme scores and self-reports of satisfaction and listening ability in difficult situations.

RESULTS

Acoustic stimulation was initially unpleasant, but approached comfort at target gain within the 3-week period. Benefit was demonstrated in continued voluntary HA use and higher bimodal phoneme scores compared to CI alone (8%-31% increases) for 4 of the participants.

CONCLUSIONS

When a second CI is not a consideration, a contralateral HA should be pursued as the standard of care for prelingually deaf adults despite substantial auditory deprivation in the previously unaided ear, unpleasant sensations at initial HA fit, or lack of dramatic objective test gains. Frequent audiologist contact, repeated HA adjustments, and client journals are valuable in promoting favorable outcomes with bimodal hearing (adaptation, acceptance, and benefit) for this population.

Systematic overview of economic evaluations of health-related rehabilitation

BACKGROUND

Health related rehabilitation is instrumental in improving functioning and promoting participation by people with disabilities. To make clinical and policy decisions about health-related rehabilitation, resource allocation and cost issues need to be considered.

OBJECTIVES

To provide an overview of systematic reviews (SRs) on economic evaluations of health-related rehabilitation.

METHODS

We searched multiple databases to identify relevant SRs of economic evaluations of health-related rehabilitation. Review quality was assessed by AMSTAR checklist.

RESULTS

We included 64 SRs, most of which included economic evaluations alongside randomized controlled trials (RCTs). The review quality was low to moderate (AMSTAR score 5-8) in 35, and high (score 9-11) in 29 of the included SRs. The included SRs addressed various health conditions, including spinal or other pain conditions (n = 14), age-related problems (11), stroke (7), musculoskeletal disorders (6), heart diseases (4), pulmonary (3), mental health problems (3), and injury (3). Physiotherapy was the most commonly evaluated rehabilitation intervention in the included SRs (n = 24). Other commonly evaluated interventions included multidisciplinary programmes (14); behavioral, educational or psychological interventions (11); home-based interventions (11); complementary therapy (6); self-management (6); and occupational therapy (4).

CONCLUSIONS

Although the available evidence is often described as limited, inconsistent or inconclusive, some rehabilitation interventions were cost-effective or showed cost-saving in a variety of disability conditions. Available evidence comes predominantly from high income countries, therefore economic evaluations of health-related rehabilitation are urgently required in less resourced settings.

Cost effectiveness of cochlear implants

PURPOSE OF REVIEW

Health professionals would be well served to have as good an understanding of cost effectiveness as clinical effectiveness, as both are critical to their patients having access to better health care and achieving better health outcomes. Cost-effectiveness evaluations allow decision makers a means of comparing different interventions when deciding resource allocation. It is a powerful tool, but like any analysis, not understanding the processes and assumptions involved leads to misinterpretation.

RECENT FINDINGS

Cost effectiveness is an economic evaluation of cost and benefit. The threshold at which an intervention is considered cost effective is reflected by the payer's "willingness to pay", which can vary considerably from country to country. These evaluations are complex and can involve the use of incomplete financial data, and subjective impressions of benefit, while excluding broader social and economic benefits.

SUMMARY

Pediatric unilateral and simultaneous bilateral cochlear implantation, and adult unilateral cochlear implantation are felt to be cost effective in the United States. Pediatric sequential cochlear implantation, adult bilateral cochlear implantation, implantation in the aged and the long deaf are not. However, cost-effectiveness economic evaluations are only part of broader assessment of social and economic benefit when determining resource allocation.

Validation of the U-STARR with the AB-York Crescent of Sound, a New Instrument to Evaluate Speech Intelligibility in Noise and Spatial Hearing Skills

The Advanced Bionics® (AB)-York crescent of sound is a new test setup that comprises speech intelligibility in noise and localization tests that represent everyday listening situations. One of its tests is the Sentence Test with Adaptive Randomized Roving levels (STARR) with sentences and noise both presented from straight ahead. For the Dutch population, we adopted the AB-York setup and replaced the English sentences with a validated set of Dutch sentences. The Dutch version of the STARR is called the Utrecht-STARR (U-STARR). This study primarily assesses the validity and reliability of the U-STARR compared to the Plomp test, which is the current Dutch gold standard for speech-in-noise testing. The outcome of both tests is a speech reception threshold in noise (SRTn). Secondary outcomes are the SRTn measured with sounds from spatially separated sources (SISSS) as well as sound localization capability. We tested 29 normal-hearing adults and 18 postlingually deafened adult patients with unilateral cochlear implants (CI). This study shows that the U-STARR is adequate and reliable and seems better suited for severely hearing-impaired persons than the conventional Plomp test. Further, CI patients have poor spatial listening skills, as demonstrated with the AB-York test.

The current state of the brain-computer interface problem

It was only 40 years ago that the first PC appeared. Over this period, rather short in historical terms, we have witnessed the revolutionary changes in lives of individuals and the entire society. Computer technologies are tightly connected with any field, either directly or indirectly. We can currently claim that computers are manifold superior to a human mind in terms of a number of parameters; however, machines lack the key feature: they are incapable of independent thinking (like a human). However, the key to successful development of humankind is collaboration between the brain and the computer rather than competition. Such collaboration when a computer broadens, supplements, or replaces some brain functions is known as the brain-computer interface. Our review focuses on real-life implementation of this collaboration.

The mismatch negativity (MMN) brain response to sound frequency changes in adult cochlear implant recipients: a follow-up study

CONCLUSION

Plasticity of auditory pitch discrimination driven by cochlear implant (CI) use uring a 2.5-year follow-up was indicated by an enhancement of the amplitude of mismatch negativity (MMN) event-related brain potential (ERP) to pure tone frequency changes.

OBJECTIVES

To follow up changes in MMN elicited to frequency and duration changes in tones during 2.5 years of CI use and to compare MMN results with audiometric speech recognition scores (SRSs).

METHODS

Postlingually deafened adults with Cochlear Nucleus CI-22 and spectra processor with SPEAK strategy were recruited. MMN was measured at 1 and 2.5 years after CI activation. Repetitive 100 ms standard tones with a frequency of 500, 1000, 2000 or 4000 Hz in separate sequences were delivered to participants concentrating on a silent movie. Deviant tones occurring infrequently among standard tones were 20% lower in frequency or 50% shorter in duration than the standards. Speech recognition ability was followed with SRSs.

RESULTS

Both time from CI activation and the frequency range of tones had significant effects on the MMN amplitude. A significant enhancement was observed for the MMN elicited by 3200 Hz deviant tones among 4000 Hz standards. Also SRSs significantly increased with time and correlated with MMN amplitudes to the 3200 Hz deviants in both measurements.