Imaging-based frequency mapping for cochlear implants - Evaluated using a daily randomized controlled trial.

Background: Due to variation in electrode design, insertion depth and cochlear morphology, patients with a cochlear implant (CI) often have to adapt to a substantial mismatch between the characteristic response frequencies of cochlear neurons and the stimulus frequencies assigned to electrode contacts. We introduce an imaging-based fitting intervention, which aimed to reduce frequency-to-place mismatch by aligning frequency mapping with the tonotopic position of electrodes. Results were evaluated in a novel trial set-up where subjects crossed over between intervention and control using a daily within-patient randomized approach, immediately from the start of CI rehabilitation. Methods: Fourteen adult participants were included in this single-blinded, daily randomized clinical trial. Based on a fusion of pre-operative imaging and a post-operative cone beam CT scan (CBCT), mapping of electrical input was aligned to natural place-pitch arrangement in the individual cochlea. That is, adjustments to the CI's frequency allocation table were made so electrical stimulation of frequencies matched as closely as possible with corresponding acoustic locations in the cochlea. For a period of three months, starting at first fit, a scheme was implemented whereby the blinded subject crossed over between the experimental and standard fitting program using a daily randomized wearing schedule, and thus effectively acted as their own control. Speech outcomes (such as speech intelligibility in quiet and noise, sound quality and listening effort) were measured with both settings throughout the study period. Results: On a group level, standard fitting obtained subject preference and showed superior results in all outcome measures. In contrast, two out of fourteen subjects preferred the imaging-based fitting and correspondingly had better speech understanding with this setting compared to standard fitting. Conclusion: On average, cochlear implant fitting based on individual tonotopy did not elicit higher speech intelligibility but variability in individual results strengthen the potential for individualized frequency fitting. The novel trial design proved to be a suitable method for evaluation of experimental interventions in a prospective trial setup with cochlear implants.

Toward neural health measurements for cochlear implantation: The relationship among electrode positioning, the electrically evoked action potential, impedances and behavioral stimulation levels.

Introduction: Estimating differences in neural health across different sites within the individual cochlea potentially enables clinical applications for subjects with a cochlear implant. The electrically evoked compound action potential (ECAP) is a measure of neural excitability that possibly provides an indication of a neural condition. There are many factors, however, that affect this measure and increase the uncertainty of its interpretation. To better characterize the ECAP response, its relationship with electrode positioning, impedances, and behavioral stimulation levels was explored. Methods: A total of 14 adult subjects implanted with an Advanced Bionics cochlear electrode array were prospectively followed up from surgery to 6 months postoperative. Insertion depth, distance to the modiolus, and distance to the medial wall were assessed for each electrode by postoperative CT analysis. ECAPs were measured intraoperatively and at three visits postoperatively on all 16 electrodes using the NRI feature of clinical programming software and characterized using multiple parameters. Impedances and behavioral stimulation levels were measured at every fitting session. Results: Patterns in ECAPs and impedances were consistent over time, but high variability existed among subjects and between different positions in the cochlea. Electrodes located closer to the apex of the cochlea and closer to the modiolus generally showed higher neural excitation and higher impedances. Maximum loudness comfort levels were correlated strongly with the level of current needed to elicit a response of 100 µV ECAP. Conclusion: Multiple factors contribute to the ECAP response in subjects with a cochlear implant. Further research might address whether the ECAP parameters used in this study will benefit clinical electrode fitting or the assessment of auditory neuron integrity.

A Multinational Cost-Consequence Analysis of a Bone Conduction Hearing Implant System-A Randomized Trial of a Conventional vs. a Less Invasive Treatment With New Abutment Technology.

Background: It is hypothesized that, for patients with hearing loss, surgically placing an implant/abutment combination whilst leaving the subcutaneous tissues intact will improve cosmetic and clinical results, increase quality of life (QoL) for the patient, and reduce medical costs. Here, incremental costs and consequences associated with soft tissue preservation surgery with a hydroxyapatite (HA)-coated abutment (test) were compared with the conventional approach, soft tissue reduction surgery with an all-titanium abutment (control). Methods: A cost-consequence analysis was performed based on data gathered over a period of 3 years in an open randomized (1:1) controlled trial (RCT) running in four European countries (The Netherlands, Spain, France, and Sweden). Subjects with conductive or mixed hearing loss or single-sided sensorineural deafness were included. Results: During the first year, in the Netherlands (NL), France (FR), and Spain (ES) a net cost saving was achieved in favor of the test intervention because of a lower cost associated with surgery time and adverse event treatments [NL €86 (CI -50.33; 219.20), FR €134 (CI -3.63; 261.30), ES €178 (CI 34.12; 97.48)]. In Sweden (SE), the HA-coated abutment was more expensive than the conventional abutment, which neutralized the cost savings and led to a negative cost (SE €-29 CI -160.27; 97.48) of the new treatment modality. After 3 years, the mean cost saving reduced to €17 (CI -191.80; 213.30) in the Netherlands, in Spain to €84.50 (CI -117.90; 289.50), and in France to €80 (CI -99.40; 248.50). The mean additional cost in Sweden increased to €-116 (CI -326.90; 68.10). The consequences in terms of the subjective audiological benefit and Health-related quality of life (HRQoL) were comparable between treatments. A trend was identified for favorable results in the test group for some consequences and statistical significance is achieved for the cosmetic outcome as assessed by the clinician. Conclusions: From this multinational cost-consequence analysis it can be discerned that health care systems can achieve a cost saving during the first year that regresses after 3 years, by implementing soft tissue preservation surgery with a HA-coated abutment in comparison to the conventional treatment. The cosmetic results are better. (sponsored by Cochlear Bone Anchored Solutions AB; Clinical and health economic evaluation with a new Baha® abutment design combined with a minimally invasive surgical technique, ClinicalTrials.gov NCT01796236).

Minimally Invasive Ponto Surgery Versus the Linear Incision Technique With Soft Tissue Preservation for Bone Conduction Hearing Implants: A Multicenter Randomized Controlled Trial.

OBJECTIVE: To compare the surgical outcomes of the Minimally Invasive Ponto Surgery (MIPS) technique with those of the linear incision technique with soft-tissue preservation for bone-anchored hearing systems (BAHS). DESIGN: Sponsor-initiated multicenter, open, randomized, controlled clinical trial. SETTING: Maastricht University Medical Centre, Ziekenhuisgroep Twente and Medisch Centrum Leeuwarden, all situated in The Netherlands. PARTICIPANTS: Sixty-four adult patients eligible for unilateral BAHS surgery.Interventions Single-stage BAHS surgery with 1:1 randomization to the linear incision technique with soft-tissue preservation (control) or the MIPS (test) group. PRIMARY AND SECONDARY OUTCOME MEASUREMENTS: Primary objective: compare the incidence of inflammation (Holgers Index ≥ 2) during 12 weeks' follow-up after surgery. Secondary objectives: skin dehiscence, pain scores, loss of sensibility around the implant, soft-tissue overgrowth, skin sagging, implant extrusion, cosmetic results, surgical time, wound healing and Implant Stability Quotient measurements. RESULTS: Sixty-three subjects were analyzed in the intention-to-treat population. No significant difference was found for the incidence of inflammation between groups. Loss of skin sensibility, cosmetic outcomes, skin sagging, and surgical time were significantly better in the test group. No statistically significant differences were found for dehiscence, pain, and soft-tissue overgrowth. A nonsignificant difference in extrusion was found for the test group. The Implant Stability Quotient was statistically influenced by the surgical technique, abutment length, and time. CONCLUSION: No significant differences between the MIPS and the linear incision techniques were observed regarding skin inflammation. MIPS results in a statistically significant reduction in the loss of skin sensibility, less skin sagging, improved cosmetic results, and reduced surgical time. Although nonsignificant, the implant extrusion rate warrants further research.

A Mid-scala Cochlear Implant Electrode Design Achieves a Stable Post-surgical Position in the Cochlea of Patients Over Time-A Prospective Observational Study.

INTRODUCTION: Cochlear implant (CI) electrode design impacts the clinical performance of patients. Stability and the occurrence of electrode array migration, which is the postoperative movement of the electrode array, were investigated using a mid-scalar electrode array and postoperative image analysis. METHODS: A prospective observational study was conducted. A mid-scalar electrode was surgically placed using a mastoidectomy, followed by a posterior tympanotomy and an extended round-window or cochleostomy insertion. A few days after surgery and 3 months later Cone Beam Computed Tomography (CBCT) was performed. The two different CBCT's were fused, and the differences between the electrode positions in three dimensions were calculated (the migration). A migration greater than 0.5 mm was deemed clinically relevant. RESULTS: Fourteen subjects participated. The mid-scalar electrode migrated in one patient (7%). This did not lead to the extrusion of an electrode contact. The mean migration of every individual electrode contact in all patients was 0.36 mm (95% confidence interval 0.22-0.50 mm), which approximates to the estimated measurement error of the CBCT technique. CONCLUSION: A mid-scalar electrode array achieves a stable position in the cochlea in a small but representative group of patients. The methods applied in this work can be used for providing postoperative feedback for surgeons and for benchmarking electrode designs.

Minimally Invasive Ponto Surgery compared to the linear incision technique without soft tissue reduction for bone conduction hearing implants: study protocol for a randomized controlled trial.

BACKGROUND: Over the last years, less invasive surgical techniques with soft tissue preservation for bone conduction hearing implants (BCHI) have been introduced such as the linear incision technique combined with a punch. Results using this technique seem favorable in terms of rate of peri-abutment dermatitis (PAD), esthetics, and preservation of skin sensibility. Recently, a new standardized surgical technique for BCHI placement, the Minimally Invasive Ponto Surgery (MIPS) technique has been developed by Oticon Medical AB (Askim, Sweden). This technique aims to standardize surgery by using a novel surgical instrumentation kit and minimize soft tissue trauma. METHODS: A multicenter randomized controlled trial is designed to compare the MIPS technique to the linear incision technique with soft tissue preservation. The primary investigation center is Maastricht University Medical Center. Sixty-two participants will be included with a 2-year follow-up period. Parameters are introduced to quantify factors such as loss of skin sensibility, dehiscence of the skin next to the abutment, skin overgrowth, and cosmetic results. A new type of sampling method is incorporated to aid in the estimation of complications. To gain further understanding of PAD, swabs and skin biopsies are collected during follow-up visits for evaluation of the bacterial profile and inflammatory cytokine expression. The primary objective of the study is to compare the incidence of PAD during the first 3 months after BCHI placement. Secondary objectives include the assessment of parameters related to surgery, wound healing, pain, loss of sensibility of the skin around the implant, implant extrusion rate, implant stability measurements, dehiscence of the skin next to the abutment, and esthetic appeal. Tertiary objectives include assessment of other factors related to PAD and a health economic evaluation. DISCUSSION: This is the first trial to compare the recently developed MIPS technique to the linear incision technique with soft tissue preservation for BCHI surgery. Newly introduced parameters and sampling method will aid in the prediction of results and complications after BCHI placement. TRIAL REGISTRATION: Registered at the CCMO register in the Netherlands on 24 November 2014: NL50072.068.14 . Retrospectively registered on 21 April 2015 at ClinicalTrials.gov: NCT02438618 . This trial is sponsored by Oticon Medical AB.

Auditory maturation in premature infants: a potential pitfall for early cochlear implantation.

OBJECTIVES/HYPOTHESIS: To describe spontaneous hearing improvement in the first years of life of a number of preterm neonates relative to cochlear implant candidacy. STUDY DESIGN: Retrospective case study. METHODS: Hearing levels of 14 preterm neonates (mean gestational age at birth = 29 weeks) referred after newborn hearing screening were evaluated. Initial hearing thresholds ranged from 40 to 105 dBHL (mean = 85 dBHL). RESULTS: Hearing level improved to normal levels for four neonates and to moderate levels for five, whereas for five neonates, no improvement in hearing thresholds was observed and cochlear implantation was recommended. Three of the four neonates in whom the hearing improved to normal levels were born prior to 28 weeks gestational age. Hearing improvement was mainly observed prior to a gestational age of 80 weeks. CONCLUSIONS: Delayed maturation of an immature auditory pathway might be an important reason for referral after newborn hearing screening in premature infants. Caution is advised regarding early cochlear implantation in preterm born infants. Audiological follow-ups until at least 80 weeks gestational age are therefore recommended.

Compensating for deviant middle ear pressure in otoacoustic emission measurements, data, and comparison to a middle ear model.

OBJECTIVE: Deviant middle ear pressure has a negative effect on the forward and backward transmission of stimulus and emissions through the middle ear. Resolving this deviant middle ear pressure is expected to lead to better middle ear transmission and, as a result of this, stronger otoacoustic emissions, which are better detectable. We investigated the effect of compensation o a deviant tympanic peak pressure on click-evoked otoacoustic emissions (CEOAEs). Second, we compared patient data to model predictions made by Zwislocki's middle ear model. SETTING: University Medical Center. PATIENTS: Fifty-nine children aged between 0.5 and 9 years (mean, 4.4 yr). INTERVENTION: Hearing investigations including CEOAE measurements at ambient and at compensated tympanic peak pressure (TPP). MAIN OUTCOME MEASURE: CEOAEs at ambient and compensated TPP. RESULTS: Compensation of TPP resulted in higher emission amplitudes below 2 kHz (increase of 8-11 dB). In addition, the compensated measurement showed an increased phase lag (up to one-fourth cycle). For ears with mild deviations of TPP, Zwislocki's model could describe these changes. Pressure compensation was well described by a compliance increase of the tympanic membrane, the malleus, and the incus. CONCLUSION: Compensating the ear canal pressure for negative tympanic peak pressure increased CEOAE amplitudes below 2 kHz and increased the phase lag. These changes can be predicted from an increase of the compliance of the tympanic membrane, incus, and malleus, as a consequence of the pressure compensation.

Bone-anchored hearing aid: a comparison of surgical techniques.

OBJECTIVE: To determine which bone-anchored hearing aid (BAHA) implantation surgical technique is associated with the fewest major postoperative complications and shortest time between surgery and use of the BAHA. The techniques evaluated were 1) a free retroauricular "full-thickness" skin graft, 2) a pedicled parieto-occipital epidermal graft, 3) a dermatome-pedicled parieto-occipital dermal graft, and 4) two broad pedicled local epidermal skin envelopes/skin flaps. STUDY DESIGN: Retrospective case study. SETTING: Tertiary referral center. PATIENTS: One hundred forty-three patients who received a BAHA at Maastricht University Medical Center between November 1996 and January 2007. Number and mean age of patients in each group: Technique 1 (n = 30; mean age, 55 yr), Technique 2 (n = 45; mean age, 54 yr), Technique 3 (n = 47; mean age, 55 yr), and Technique 4 (n = 21; mean age, 54 yr). MAIN OUTCOME MEASURES: Cumulative proportion of implants that remained free of major complications versus follow-up interval, time between surgery and use of BAHA. RESULTS: Technique 4 (2 broad pedicled local epidermal envelopes/skin flaps) has a significantly higher proportion of implants that remained free of major complications during first year of follow-up (91%; p = 0.021). Pairwise comparisons revealed that Technique 4 also has a significantly shorter time until use (2 mo) than Techniques 1 (2.5 mo), 2, and 3 (both 2.3 mo). CONCLUSION: Two broad pedicled, local epidermal envelopes/flaps are associated with significantly fewer major complications and have one of the shortest times between surgery and use of the BAHA. The use of a dermatome is not associated with fewer major complications. We recommend Technique 4 as the preferred standard in BAHA surgery to minimize complications, postoperative medication, discomfort, and cost.