Self-Assessment of Cochlear Health by New Cochlear Implant Recipients: Daily Impedance, Electrically Evoked Compound Action Potential and Electrocochleography Measurements Over the First Three Postoperative Months.

HYPOTHESES: In newly implanted cochlear implant (CI) users, electrically evoked compound action (eCAPs) and electrocochleography (ECochGs) will remain stable over time. Electrode impedances will increase immediately postimplantation due to the initial inflammatory response, before decreasing after CI switch-on and stabilizing thereafter. BACKGROUND: The study of cochlear health (CH) has several applications, including explaining variation in CI outcomes, informing CI programming strategies, and evaluating the safety and efficacy of novel biological treatments for hearing loss. Very early postoperative CH patterns have not previously been intensively explored through longitudinal daily testing. Thanks to technological advances, electrode impedances, eCAPs, and ECochGs can be independently performed by CI users at home to monitor CH over time. METHODS: A group of newly implanted CI users performed daily impedances, eCAPs, and ECochGs for 3 months at home, starting from the first day postsurgery (N = 7) using the Active Insertion Monitoring system by Advanced Bionics. RESULTS: Measurement validity of 93.5, 93.0, and 81.6% for impedances, eCAPs, and ECochGs, respectively, revealed high participant compliance. Impedances increased postsurgery before dropping and stabilizing after switch-on. eCAPs showed good stability, though statistical analyses revealed a very small but significant increase in thresholds over time. Most ECochG thresholds did not reach the liberal signal-to-noise criterion of 2:1, with low threshold stability over time. CONCLUSION: Newly implanted CI recipients can confidently and successfully perform CH recordings at home, highlighting the valuable role of patients in longitudinal data collection. Electrode impedances and eCAPs are promising objective measurements for evaluating CH in newly implanted CI users.

Self-assessment of cochlear health by cochlear implant recipients.

Recent technological advances in cochlear implant (CI) telemetry have enabled, for the first time, CI users to perform cochlear health (CH) measurements through self-assessment for prolonged periods of time. This is important to better understand the influence of CH on CI outcomes, and to assess the safety and efficacy of future novel treatments for deafness that will be administered as adjunctive therapies to cochlear implantation. We evaluated the feasibility of using a CI to assess CH and examined patterns of electrode impedances, electrically-evoked compound action potentials (eCAPs) and electrocochleography (ECochGs), over time, in a group of adult CI recipients. Fifteen subjects were trained to use the Active Insertion Monitoring tablet by Advanced Bionics, at home for 12 weeks to independently record impedances twice daily, eCAPs once weekly and ECochGs daily in the first week, and weekly thereafter. Participants also completed behavioral hearing and speech assessments. Group level measurement compliance was 98.9% for impedances, 100% for eCAPs and 99.6% for ECochGs. Electrode impedances remained stable over time, with only minimal variation observed. Morning impedances were significantly higher than evening measurements, and impedances increased toward the base of the cochlea. eCAP thresholds were also highly repeatable, with all subjects showing 100% measurement consistency at, at least one electrode. Just over half of all subjects showed consistently absent thresholds at one or more electrodes, potentially suggesting the existence of cochlear dead regions. All subjects met UK NICE guidelines for cochlear implantation, so were expected to have little residual hearing. ECochG thresholds were, unsurprisingly, highly erratic and did not correlate with audiometric thresholds, though lower ECochG thresholds showed more repeatability over time than higher thresholds. We conclude that it is feasible for CI users to independently record CH measurements using their CI, and electrode impedances and eCAPs are promising measurements for objectively assessing CH.

Cochlear Implantation in Neurofibromatosis Type 2: Experience From the UK Neurofibromatosis Type 2 Service.

OBJECTIVE: To review the outcomes of cochlear implants (CI) in patients with neurofibromatosis type 2 (NF2) in a large cohort, and identify factors associated with poor hearing benefit. STUDY DESIGN: Fifteen-year retrospective national observational case series. SETTING: United Kingdom regional NF2 multidisciplinary teams. PATIENTS: Consecutive patients with NF2 receiving a CI. INTERVENTIONS: CI for hearing rehabilitation. MAIN OUTCOME MEASURES: 1) Audiometric performance at 9 to 12 months after implantation using City University of New York (CUNY) sentence recognition score, and Bamford- Kowal-Bench (BKB) word recognition score in quiet (BKBq), and in noise (BKBn). 2) CI use at most recent review. RESULTS: Sixty four consecutive patients, median age 43 years, were included. Nine to 12 months mean audiometric scores were: CUNY 60.9%, BKBq 45.8%, BKBn 41.6%. There was no difference in audiometric outcomes between VS treatment modalities. At most recent review (median 3.6 years from implantation), 84.9% with device in situ/available data were full or part-time users. Between 9 and 12 months and most recent review there was an interval reduction in mean audiometric scores: CUNY -12.9%, BKBq -3.3%, BKBn -4.9%. Larger tumor size and shorter duration of profound hearing loss were the only variables associated with poorer audiometric scores. Tumor growth at the time of surgery was the only variable associated with CI non-use. Individual patient response was highly variable. CONCLUSIONS: CI can provide significant and sustained auditory benefits to patients with NF2 independent of tumor treatment modality, with the majority of those implanted becoming at least part-time users. Larger datasets are required to reliably assess the role of independent variables.

Establishing Reproducibility and Correlation of Cochlear Microphonic Amplitude to Implant Electrode Position Using Intraoperative Electrocochleography and Postoperative Cone Beam Computed Tomography.

OBJECTIVES: The primary objective of this study was to establish the reproducibility of cochlear microphonic (CM) recordings obtained from a cochlear implant (CI) electrode contact during and immediately after insertion. This was achieved by evaluating the insertion angle and calculating the position of the apical electrode contact during insertion, using postoperative cone beam computed tomography (CBCT). The secondary objective was to create individualized patient maps of electrode contacts located within acoustically sensitive regions by correlating the CM amplitude to the electrode position determined using CBCT. METHODS: CMs were recorded from a CI electrode contact during and immediately after insertion in 12 patients (n = 14 ears). Intraoperative recordings were made for a 0.5 kHz tone burst stimulus and were recorded from the apical electrode contact. Postinsertion recordings were made from the odd-numbered electrode contacts (1-15) along the array, using a range of stimulus frequencies (from 0.125 to 2 kHz). The time point at which each electrode contact passed through the round window was noted throughout the insertion, and the CM amplitude at this point was correlated to postoperative CBCT. This correlation was then used to estimate the CM amplitude at particular points within the cochlea, which was in turn compared with the amplitudes recorded from each electrode postoperatively to assess the reproducibility of the recordings. RESULTS: Significant correlation was shown between intraoperative insertion and postinsertion angles at two amplitude events (maximum amplitude: 29° mean absolute error, r = 0.77, p = 0.006; 10% of maximum amplitude: 52° mean absolute error, r = 0.85, p = 0.002). CONCLUSION: We have developed a novel method to demonstrate the reproducibility of the CM responses recorded from a CI electrode during insertion. By correlating the CM amplitude with the postoperative CBCT, we have also been able to create individualized maps of CM responses, categorizing the cochlea into acoustically responsive and unresponsive regions. If the electrode contacts within the acoustically sensitive regions are shown to be associated with improved loudness discrimination, it could have implications for optimal electrode mapping and placement.

The Outcomes of Cochlear Implantation in Elderly Patients: A Single United Kingdom Center Experience.

OBJECTIVES: The average life expectancy in the United Kingdom is currently nearly 80 years for a newborn baby with nearly 15% of the population, by 2040, being >75 years old. Hearing impairment is a common disability in the elderly individual, and there have been significant drives to support this population to lead longer and healthier working lives. We aimed to assess the long-term audiological and health-related quality-of-life benefits of cochlear implants (CI) in elderly individuals. METHODS: A retrospective and cross-sectional study of patients who received a CI at ≥70 years. Data extracted included speech perception scores, adverse events, telephone use, and patient-reported outcome measures using the Glasgow Benefit Inventory questionnaire with a minimum of 12 months follow-up. RESULTS: Sixty-four patients aged ≥70 years received a unilateral CI. A significant improvement in speech perception scores in all conditions was noted with no significant difference between differing age groups. Glasgow Benefit Inventory scores showed a significant positive impact on patients' lives and their health status, with no significant difference between the differing age groups. CONCLUSIONS: Cochlear implantation is a safe and well-tolerated procedure in the elderly patients with significant improvements observed in audiological performance, health status, and social interactions.

A systematic review of the impact of adjusting input dynamic range (IDR), electrical threshold (T) level and rate of stimulation on speech perception ability in cochlear implant users.

OBJECTIVE: To systematically review the evidence of how adjustments of the electrical threshold (T) level, input dynamic range (IDR) and electrical stimulation rate impact on speech perception for cochlear implant (CI) users. DESIGN: Systematic review. STUDY SAMPLE: A search of two electronic data sources yielded 32 studies, which met the inclusion criteria. A quality assessment and two evidence-based practice (EBP) review rating schemes were used to grade studies. RESULTS: Due to the heterogeneity of speech perception measures, CI device type and study design, comparisons were made by structured review. CONCLUSION: The quality of studies was found to be moderate to poor. Increasing T levels above behavioural threshold, or as a proportion of electrical dynamic range (EDR), has been demonstrated to improve perception of monosyllables in quiet and sentences in both quiet and in noise. Specific IIDR and IDR setting may improve perception of monosyllables in quiet and sentences in noise. However, no recommendation could be determined for setting rate of stimulation as speech perception varied significantly across rates examined. To optimise speech perception, a bespoke approach to parameter setting providing an individualised CI fitting is recommended; however, detail of how to optimise settings and the interactions between parameters is as yet unknown.

Evaluating the effectiveness and reliability of the Vibrant Soundbridge and Bonebridge auditory implants in clinical practice: Study design and methods for a multi-centre longitudinal observational study.

BACKGROUND: The Vibrant Soundbridge middle ear implant and the Bonebridge bone conducting hearing device are hearing implants that use radio frequency transmission to send information from the sound processor to the internal transducer. This reduces the risk of skin problems and infection but requires a more involved surgical procedure than competitor skin penetrating devices. It is not known whether more complex surgery will lead to additional complications. There is little information available on the reliability of these systems and adverse medical or surgical events. The primary research question is to determine the reliability and complication rate for the Vibrant Soundbridge and Bonebridge. The secondary research question explores changes in quality of life following implantation of the devices. The tertiary research question looks at effectiveness via changes in auditory performance. METHOD: The study was designed based on a combination of a literature search, two clinician focus groups and expert review.A multi-centre longitudinal observational study was designed. There are three study groups, two will have been implanted prior to the start of the study and one group, the prospective group, will be implanted after initiation of the study. Outcomes are surgical questionnaires, measures of quality of life, user satisfaction and speech perception tests in quiet and in noise. CONCLUSION: This is the first multi-centre study to look at these interventions and includes follow up over time to understand effectiveness, reliability, quality of life and complications.

Preliminary assessment of the feasibility of using AB words to assess candidacy in adults.

BACKGROUND: Adult cochlear implant (CI) candidacy is assessed in part by the use of speech perception measures. In the United Kingdom the current cut-off point to fall within the CI candidacy range is a score of less than 50% on the BKB sentences presented in quiet (presented at 70 dBSPL). GOAL: The specific goal of this article was to review the benefit of adding the AB word test to the assessment test battery for candidacy. RESULTS: The AB word test scores showed good sensitivity and specificity when calculated based on both word and phoneme scores. The word score equivalent for 50% correct on the BKB sentences was 18.5% and it was 34.5% when the phoneme score was calculated; these scores are in line with those used in centres in Wales (15% AB word score). CONCLUSION: The goal of the British Cochlear Implant Group (BCIG) service evaluation was to determine if the pre-implant assessment measures are appropriate and set at the correct level for determining candidacy, the future analyses will determine whether the speech perception cut-off point for candidacy should be adjusted and whether other more challenging measures should be used in the candidacy evaluation.

Assessment of 'Fitting to Outcomes Expert' FOX™ with new cochlear implant users in a multi-centre study.

OBJECTIVE: To compare the fitting time requirements and the efficiency in achieving improvements in speech perception during the first 6 months after initial stimulation of computer-assisted fitting with the Fitting to Outcome eXpert' (FOX) and a standard clinical fitting procedure. METHOD: Twenty-seven post-lingually deafened adults, newly implanted recipients of the Advanced Bionics HiRes 90K™ cochlear implant from Germany, the UK, and France took part in a controlled, randomized, clinical study. Speech perception was measured for all participants and fitting times were compared across groups programmed using FOX and conventional programming methods. RESULTS: The fitting time for FOX was significantly reduced at 14 days (P < 0.001) but equivalent over the 6-month period. The groups were not well matched for duration of deafness; therefore, speech perception could not be compared across groups. DISCUSSION: Despite including more objective measures of performance than a standard fitting approach and the adjustment of a greater range of parameters during initial fitting, FOX did not add to the overall fitting time when compared to the conventional approach. FOX significantly reduced the fitting time in the first 2 weeks and by providing a standard fitting protocol, reduced variability across centres. CONCLUSIONS: FOX computer-assisted fitting can be successfully used at switch on, in different clinical environments, reducing fitting time in the first 2 weeks and is efficient at providing a usable program.

Comparison of the benefits of cochlear implantation versus contra-lateral routing of signal hearing aids in adult patients with single-sided deafness: study protocol for a prospective within-subject longitudinal trial.

BACKGROUND: Individuals with a unilateral severe-to-profound hearing loss, or single-sided deafness, report difficulty with listening in many everyday situations despite having access to well-preserved acoustic hearing in one ear. The standard of care for single-sided deafness available on the UK National Health Service is a contra-lateral routing of signals hearing aid which transfers sounds from the impaired ear to the non-impaired ear. This hearing aid has been found to improve speech understanding in noise when the signal-to-noise ratio is more favourable at the impaired ear than the non-impaired ear. However, the indiscriminate routing of signals to a single ear can have detrimental effects when interfering sounds are located on the side of the impaired ear. Recent published evidence has suggested that cochlear implantation in individuals with a single-sided deafness can restore access to the binaural cues which underpin the ability to localise sounds and segregate speech from other interfering sounds. METHODS/DESIGN: The current trial was designed to assess the efficacy of cochlear implantation compared to a contra-lateral routing of signals hearing aid in restoring binaural hearing in adults with acquired single-sided deafness. Patients are assessed at baseline and after receiving a contra-lateral routing of signals hearing aid. A cochlear implant is then provided to those patients who do not receive sufficient benefit from the hearing aid. This within-subject longitudinal design reflects the expected care pathway should cochlear implantation be provided for single-sided deafness on the UK National Health Service. The primary endpoints are measures of binaural hearing at baseline, after provision of a contra-lateral routing of signals hearing aid, and after cochlear implantation. Binaural hearing is assessed in terms of the accuracy with which sounds are localised and speech is perceived in background noise. The trial is also designed to measure the impact of the interventions on hearing- and health-related quality of life. DISCUSSION: This multi-centre trial was designed to provide evidence for the efficacy of cochlear implantation compared to the contra-lateral routing of signals. A purpose-built sound presentation system and established measurement techniques will provide reliable and precise measures of binaural hearing. TRIAL REGISTRATION: Current Controlled Trials http://www.controlled-trials.com/ISRCTN33301739 (05/JUL/2013).

Cochlear implantation in patients with vestibular schwannoma: a single United Kingdom center experience.

OBJECTIVES/HYPOTHESIS: To evaluate the outcome of cochlear implantation (CI) in patients with vestibular schwannoma (VS). STUDY DESIGN: A retrospective case series from a tertiary auditory implant center. METHODS: A retrospective case note review was carried out to evaluate patients with bilateral profound hearing loss and VS who underwent unilateral CI within the Auditory Implant Centre at St. Thomas' Hospital, London, between 2000 and 2012. This included both bilateral VS with neurofibromatosis type 2 (NF2) and unilateral sporadic VS. Outcome measures included speech perception with Bamford-Kowal-Bench and City University of New York sentences, sound-field thresholds with warble tones, and the subjective benefits reported by patients. RESULTS: The study included five patients with NF2 and bilateral VS and two patients with sporadic unilateral VS. The standard preoperative audiologic assessment for CI often could not be carried out in NF2 patients. Preoperative testing was more complete in the two patients with sporadic VS. The audiologic outcome was variable. Open-set speech perception was achieved in three out of five NF2 patients, and another reported significant improvement in environmental sound perception and ease of communication. The outcome was overall better in patients with sporadic VS, both of whom were able to use the telephone in their implanted ear. CONCLUSIONS: Good speech perception can be achieved in some cases, and CI should be considered as an option for auditory rehabilitation in patients with VS.

STARR: a speech test for evaluation of the effectiveness of auditory prostheses under realistic conditions.

OBJECTIVES: The objective was to develop and evaluate a new sentence test, the Sentence Test with Adaptive Randomized Roving levels, intended to emulate everyday listening experience, using both normal-hearing (NH) and cochlear implant (CI) groups, examining practicality, learning, test-retest variability, and interlist variability. DESIGN: In experiment 1, each of 25 NH adults was tested using five lists, each comprising 30 sentences. One male and one female speaker each spoke 15 sentences. Ten sentences were presented at each of three presentation levels: 50, 65, and 80 dB SPL. The relative level of a speech-shaped noise was varied adaptively to estimate the speech reception threshold (SRT). Counterbalance for list order was achieved by staggering the allocation of lists to participants. To allow assessment of learning effects, no practice was given. The variability of mean SRTs across lists was small, but correction factors were derived for each list so that, after correction, all lists gave the same mean SRT. Test-retest variability was estimated by examining the corrected SRTs for each subject's five lists. In experiment 2, 25 CI users each received one test list after a small amount of practice. Experiment 3 examined the effect of speech rate using time-compressed speech, for age-matched NH and CI users. RESULTS: The mean SRT for the NH participants was approximately -6 dB and was similar for the male and female speakers. There was a small but significant improvement in SRTs between the first and later lists administered, but no further improvement for subsequent lists. On the basis of the variability of the corrected SRTs within each participant, a 2.2 dB difference in SRT is meaningful for comparisons using one test list per condition, for a single participant. The percentage of key words correct varied with presentation level over a 13% range, being best at 65 dB SPL. Only 40% of the CI group achieved an SRT lower than 20 dB for both speakers. There was large individual variability in the SRTs, and SRTs were higher for the female than for the male speaker. For the CI participants, the percentage of key words correct varied markedly with level, from 19% at the lowest level to 57% at the medium level. Time compression had a small effect for NH participants but a very large effect for CI participants. CONCLUSIONS: The Sentence Test with Adaptive Randomized Roving levels seems practical to administer and is reasonably sensitive. For NH participants, a 2.2 dB difference in SRT is meaningful for a single list per condition and a single participant. Although learning effects were small for NH participants, it seems prudent to provide some practice sentences when testing hearing-impaired or CI participants. The very large effect of time compression for the CI group has implications for live voice testing of children, because speech rate is only poorly controlled in such testing.

Outcome of bone-anchored hearing aids for single-sided deafness: a prospective study.

CONCLUSION: The bone-anchored hearing aid (BAHA) system can offer significant benefits to patients with single-sided deafness (SSD), primarily by lifting the head shadow effect. OBJECTIVE: To evaluate the efficacy of BAHA for SSD by comparing pre- and postoperative speech, spatial and qualities of hearing scale (SSQ) scores. METHODS: This was a prospective study conducted within a tertiary auditory implant department. The inclusion criteria were unilateral profound hearing loss with normal or mild high frequency hearing loss in the hearing ear (pure tone average better than or equal to 25 dBHL measured at 0.5, 1, 2 and 3 kHz) and subjective benefits reported by patients following a home trial with a BAHA Softband. Patients who met the above criteria and opted for surgery were asked to complete the SSQ questionnaire. The postoperative SSQ response was collected after at least 6 months of consistent BAHA usage. RESULTS: This study included 25 adult patients (mean age at implantation 57.5 years). There was a statistically significant improvement in the average SSQ score in all three sections of the questionnaire with the use of the BAHA. Our patients experienced most marked benefits in speech hearing in challenging listening situations. All patients remain consistent users and there has been no explantation to date.

The effect of Gaussian noise on the threshold, dynamic range, and loudness of analogue cochlear implant stimuli.

The deliberate addition of Gaussian noise to cochlear implant signals has previously been proposed to enhance the time coding of signals by the cochlear nerve. Potentially, the addition of an inaudible level of noise could also have secondary benefits: it could lower the threshold to the information-bearing signal, and by desynchronization of nerve discharges, it could increase the level at which the information-bearing signal becomes uncomfortable. Both these effects would lead to an increased dynamic range, which might be expected to enhance speech comprehension and make the choice of cochlear implant compression parameters less critical (as with a wider dynamic range, small changes in the parameters would have less effect on loudness). The hypothesized secondary effects were investigated with eight users of the Clarion cochlear implant; the stimulation was analogue and monopolar. For presentations in noise, noise at 95% of the threshold level was applied simultaneously and independently to all the electrodes. The noise was found in two-alternative forced-choice (2AFC) experiments to decrease the threshold to sinusoidal stimuli (100 Hz, 1 kHz, 5 kHz) by about 2.0 dB and increase the dynamic range by 0.7 dB. Furthermore, in 2AFC loudness balance experiments, noise was found to decrease the loudness of moderate to intense stimuli. This suggests that loudness is partially coded by the degree of phase-locking of cochlear nerve fibers. The overall gain in dynamic range was modest, and more complex noise strategies, for example, using inhibition between the noise sources, may be required to get a clinically useful benefit.