Management of Severe Facial Nerve Cross Stimulation by Cochlear Implant Replacement to Change Pulse Shape and Grounding Configuration: A Case-series.

OBJECTIVES: To investigate the combined effect of changing pulse shape and grounding configuration to manage facial nerve stimulation (FNS) in cochlear implant (CI) recipients. PATIENTS: Three adult CI recipients with severe FNS were offered a replacement implant when standard stimulation strategies and programming adjustments did not resolve symptoms. Our hypothesis was that the facial nerve was less likely to be activated when using anodic pulses with "mixed-mode" intra-cochlear and extra-cochlear current return. INTERVENTION: All patients were reimplanted with an implant that uses a pseudo-monophasic anodic pulse shape, with mixed-mode grounding (stimulus mixed-mode anodic)-the Neuro Zti CI (Oticon Medical). This device also allows measurements of neural function and loudness with monopolar, symmetric biphasic pulses (stimulus MB), the clinical standard used by most CIs as a comparison. MAIN OUTCOME MEASURES: The combined effect of pulse shape and grounding configuration on FNS was monitored during surgery. Following CI activation, FNS symptoms and performance with the Neuro Zti implant were compared with outcomes before reimplantation. RESULTS: FNS could only be recorded using stimulus MB for all patients. In clinical use, all patients reported reduced FNS and showed an improvement in Bamford-Kowal-Bench sentences recognition compared with immediately before reimplantation. Bamford-Kowal-Bench scores with a male speaker were lower compared with measurements taken before the onset of severe FNS for patients 1 and 2. CONCLUSIONS: In patients where CI auditory performance was severely limited by FNS, charge-balanced pseudo-monophasic stimulation mode with a mixed-mode grounding configuration limited FNS and improved loudness percept compared with standard biphasic stimulation with monopolar grounding.

Cochlear implants in the management of hearing loss in Neurofibromatosis Type 2.

OBJECTIVE: Review of cochlear implant (CI) outcomes in patients with Neurofibromatosis Type 2 (NF2), implanted in the presence of an ipsilateral vestibular schwannoma (VS). Hearing restoration was combined in some cases with a Bevacizumab regime. METHOD: Retrospective review of 12 patients, managed over the period 2009-2016, at a tertiary referral multidisciplinary NF2 clinic. The patients are grouped by hearing outcomes to explore likely protective factors, and to generate a proposed decision-making tool for the selection of either CI or Auditory Brainstem Implant (ABI). RESULTS: Four of the 12 patients achieved speech discrimination without lip-reading. In these individuals there is reason to think that the mechanism of their hearing loss was cochlear dysfunction. A further four patients received benefit to lip-reading and awareness of environmental sound. For such patients their hearing loss may have been due to both cochlear and neural dysfunction. Two patients gained access to environmental sound only from their CI. Two patients derived no benefit from their CIs, which were subsequently explanted. Both these latter patients had had prior ipsilateral tumour surgery, one just before the CI insertion. CONCLUSION: Cochlear implantation can lead to open set speech discrimination in patients with NF2 in the presence of a stable VS. Use of promontory stimulation and intraoperative electrically evoked auditory brainstem response testing, along with case history, can inform the decision whether to implant an ABI or CI.

Pitch Discrimination: An Independent Factor in Cochlear Implant Performance Outcomes.

OBJECTIVE: To assess differences in pitch-ranking ability across a range of speech understanding performance levels and as a function of electrode position. STUDY DESIGN: An observational study of a cross-section of cochlear implantees. SETTING: Tertiary referral center for cochlear implantation. PATIENTS: A total of 22 patients were recruited. All three manufacturers' devices were included (MED-EL, Innsbruck, Austria, n = 10; Advanced Bionics, California, USA, n = 8; and Cochlear, Sydney, Australia, n = 4) and all patients were long-term users (more than 18 months). Twelve of these were poor performers (scores on BKB sentence lists <60%) and 10 were excellent performers (BKB >90%). INTERVENTION: After measurement of threshold and comfort levels, and loudness balancing across the array, all patients underwent thorough pitch-ranking assessments at 80% of comfort levels. MAIN OUTCOME MEASURE: Ability to discriminate pitch across the electrode array, measured by consistency in discrimination of adjacent pairs of electrodes, as well as an assessment of the pitch order across the array using the midpoint comparison task. RESULTS: Within the poor performing group there was wide variability in ability to pitch rank, from no errors, to a complete inability to reliably and consistently differentiate pitch change across the electrode array. Good performers were overall significantly more accurate at pitch ranking (p = 0.026). Consistent pitch ranking was found to be a significant independent predictor of BKB score, even after adjusting for age. Users of the MED-EL implant experienced significantly more pitch confusions at the apex than at more basal parts of the electrode array. CONCLUSIONS: Many cochlear implant users struggle to discriminate pitch effectively. Accurate pitch ranking appears to be an independent predictor of overall outcome. Future work will concentrate on manipulating maps based upon pitch discrimination findings in an attempt to improve speech understanding.

English consensus protocol evaluating candidacy for auditory brainstem and cochlear implantation in neurofibromatosis type 2.

OBJECTIVE: Hearing loss resulting from bilateral vestibular schwannomas (VSs) has a significant effect on the quality of life of patients with neurofibromatosis Type 2 (NF2). A national consensus protocol was produced in England as a guide for cochlear implantation (CI) and auditory brainstem implantation (ABI) in these patients. STUDY DESIGN: Consensus statement. SETTING: English NF2 Service. PARTICIPANTS: Clinicians from all 4 lead NF2 units in England. MAIN OUTCOME MEASURES: A protocol for the assessment, insertion and rehabilitation of CI and ABI in NF2 patients. RESULTS: Patients should undergo more detailed hearing assessment once their maximum aided speech discrimination score falls below 50% in the better hearing ear. Bamford-Kowal-Bench sentence testing scores below 50% should trigger assessment for auditory implantation, as recommended by the National Institute for Clinical Excellence guidelines on CI. Where this occurs in patients with bilateral stable VS or a unilateral stable VS where the contralateral cochlear nerve was lost at previous surgery, CI should be considered. Where VS surgery is planned, CI should be considered where cochlear nerve preservation is thought possible, otherwise an ABI should be considered. Intraoperative testing using electrically evoked auditory brainstem responses or cochlear nerve action potentials may be used to determine whether a CI or ABI is inserted. CONCLUSION: The NF2 centers in England agreed on this protocol. Multisite, prospective assessments of standardized protocols for auditory implantation in NF2 provide an essential model for evaluating candidacy and outcomes in this challenging patient population.

Surgical management of vestibular schwannomas and hearing rehabilitation in neurofibromatosis type 2.

OBJECTIVES: To report our approach to the surgical management of vestibular schwannomas (VSs) and hearing rehabilitation in neurofibromatosis Type 2 (NF2). DESIGN: Retrospective cohort study. SETTING: Tertiary referral NF2 unit. PATIENTS: Between 1981 and 2011, seventy-five patients were managed in our NF2 unit, of which, 58 patients are under current review. MAIN OUTCOME MEASURES: Patients who underwent VS excision were evaluated for tumor size, surgical approach, and outcomes of hearing and facial nerve function. All current patients were evaluated for NF2 mutation, hearing, and auditory implantation outcomes. RESULTS: Forty-four patients underwent resection of 50 VS in our unit, of which, 14% had facial neuroma excision and reinnervation during the same operation. At 12 months after surgery, facial nerve outcomes were House-Brackmann (HB) 1 in 33%, HB2 in 21%, and HB3 in 30%. Total VS resection was achieved in 78% of patients using a translabyrinthine approach. Seventy-two percent of the current patients have American Association of Otolaryngology-Head and Neck Surgery class A to C hearing (maximum speech discrimination score over 50%) in the better hearing ear, and a further 14% are full-time users of cochlear implants or auditory brainstem implants. The remaining patients have been assessed for auditory implantation. CONCLUSION: By following a policy of treating VS in NF2 patients where tumor growth is observed, complete tumor resection can be achieved through a translabyrinthine approach while achieving comparable facial nerve outcomes to published series. We advocate proactive hearing rehabilitation in all patients with timely assessment for auditory implantation to maintain quality of life.

Benefits of the HiRes 120 coding strategy combined with the Harmony processor in an adult European multicentre study.

CONCLUSION: The Harmony processor was found to be reliable, comfortable and offered a substantially increased battery life compared with the previous generation processor. No significant improvement in speech understanding with HiRes was demonstrated from objective measures, but the majority of subjects showed a clear subjective preference for the combination HiRes 120/Harmony processor. OBJECTIVES: To evaluate experience with the Harmony™ sound processor, together with the HiRes 120 strategy. METHODS: Postlingually deafened adults implanted with a CII or HiRes 90K were included and divided into three groups: (1) experienced users using the Platinum body-worn processor; (2) experienced users who had been using other processors; (3) new users with the Harmony processor from first fitting. The latter group entered a randomized crossover protocol where half were initially fitted with HiRes and half with HiRes 120. The initial strategy was used for 3 months and the alternative for a further 3 months. Speech perception tests and questionnaires were performed. RESULTS: The study included 65 subjects. Implementing HiRes 120 was straightforward. The speech test group results did not show significant differences between HiRes and HiRes 120. However, the questionnaires showed significantly higher ratings for HiRes 120 in some instances. Subjects were highly satisfied with the Harmony processor.

The use of Lean Thinking techniques in implementing the Department of Health, UK, 18-week waiting time directive for cochlear implantation.

In October 2007, Primary Care Trusts throughout the East of England agreed to fund assessment and implantation for all patients referred to Cambridge University Hospitals' Cochlear Implant Unit ('the Unit') providing they met locally agreed criteria. Subsequently, the Unit has employed Lean Thinking techniques to maximize departmental efficiency in order to comply with the Department of Health's 18-week guideline. Analysis of the patient's pathway, from referral to implantation surgery, highlighted areas of 'waste' that were causing delays in downstream processes. Through a number of streamlining measures a large waiting list of long-waiting patients (n = 141) has been cleared. Of those patients not receiving a preliminary hearing aid trial, 89% were implanted within 18 weeks (31/35 patients). Of those receiving the hearing aid trial 100% were assessed and commenced on the trial within 18 weeks, and 47% received implantation within the allotted time frame (7/15 patients). The Unit is continuing to monitor these processes to ensure these change s are continuing to maintain shorter waiting times. Equally, patients must feel that they have received optimal care and received sufficient information throughout the entire patient pathway.

Bilateral sequential cochlear implantation in the congenitally deaf child: evidence to support the concept of a 'critical age' after which the second ear is less likely to provide an adequate level of speech perception on its own.

This study attempts to answer the question of whether there is a 'critical age' after which a second contralateral cochlear implant is less likely to provide enough speech perception to be of practical use. The study was not designed to predict factors that determine successful binaural implant use, but to see if there was evidence to help determine the latest age at which the second ear can usefully be implanted, should the first side fail and become unusable.Outcome data, in the form of speech perception test results, were collected from 11 cochlear implant programmes in the UK and one centre in Australia. Forty-seven congenitally bilaterally deaf subjects who received bilateral sequential implants were recruited to the study. The study also included four subjects with congenital unilateral profound deafness who had lost all hearing in their only hearing ear and received a cochlear implant in their unilaterally congenitally deaf ear. Of those 34 subjects for whom complete sets of data were available, the majority (72%) of those receiving their second (or unilateral) implant up to the age of 13 years scored 60 per cent or above in the Bamford Kowal Bench (BKB) sentence test, or equivalent. In contrast, of those nine receiving their second or unilateral implant at the age of 15 or above, none achieved adequate levels of speech perception on formal testing: two scored 29 per cent and 30 per cent, respectively, and the rest seven per cent or less.A discriminant function analysis performed on the data suggests that it is unlikely that a second contralateral implant received after the age of 16 to 18 years will, on its own, provide adequate levels of speech perception. As more children receive sequential bilateral cochlear implants and the pool of data enlarges the situation is likely to become clearer.The results provide support for the concept of a 'critical age' for implanting the second ear in successful congenitally deaf unilateral cochlear implant users. This would argue against 'preserving' the second ear beyond a certain age, in order to use newer models of cochlear implant or for the purpose of hair cell regeneration and similar procedures in the future. The results suggest a new and more absolute reason for bilateral implantation of congenitally deaf children at an early age.