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1.
Hear Res ; 447: 109011, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38692015

RESUMO

This study introduces and evaluates the PHAST+ model, part of a computational framework designed to simulate the behavior of auditory nerve fibers in response to the electrical stimulation from a cochlear implant. PHAST+ incorporates a highly efficient method for calculating accommodation and adaptation, making it particularly suited for simulations over extended stimulus durations. The proposed method uses a leaky integrator inspired by classic biophysical nerve models. Through evaluation against single-fiber animal data, our findings demonstrate the model's effectiveness across various stimuli, including short pulse trains with variable amplitudes and rates. Notably, the PHAST+ model performs better than its predecessor, PHAST (a phenomenological model by van Gendt et al.), particularly in simulations of prolonged neural responses. While PHAST+ is optimized primarily on spike rate decay, it shows good behavior on several other neural measures, such as vector strength and degree of adaptation. The future implications of this research are promising. PHAST+ drastically reduces the computational burden to allow the real-time simulation of neural behavior over extended periods, opening the door to future simulations of psychophysical experiments and multi-electrode stimuli for evaluating novel speech-coding strategies for cochlear implants.


Assuntos
Potenciais de Ação , Adaptação Fisiológica , Implantes Cocleares , Nervo Coclear , Simulação por Computador , Estimulação Elétrica , Modelos Neurológicos , Nervo Coclear/fisiologia , Animais , Humanos , Fatores de Tempo , Implante Coclear/instrumentação , Biofísica , Estimulação Acústica
2.
Otol Neurotol ; 45(4): e322-e327, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38378178

RESUMO

OBJECTIVE: To evaluate the clinical applicability of a semiautomatic radiological tool for scalar translocation detection. STUDY DESIGN: Retrospective study. SETTING: Tertiary care academic center. PATIENTS: We included 104 patients implanted with 116 HiFocus Mid-Scala electrode arrays between January 2013 and September 2016. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: The tool's scalar position assessments were compared with manual ones by calculating intraclass coefficient (ICC) for individual contacts and sensitivity and specificity for translocation detection of the whole array. In addition, ICC was calculated for diameters A and B, ratio A/B, and angular insertion depth (AID). RESULTS: Nine-one percent of cases could be processed, which took 5 to 10 minutes per case. Comparison of manual and semiautomatic scalar position showed for individual contacts an ICC of 0.89 and for the whole array a sensitivity of 97% and a specificity of 96%. ICCs for A, B, and A/B were 0.82, 0.74, and 0.39 respectively. For AID, ICC of each of the 16 contacts was 0.95 or higher. CONCLUSIONS: The semiautomatic radiological tool could analyze most cases and showed good to excellent agreement with manual assessments for translocation detection, diameter A, diameter B, and AID. The variability between semiautomatic and manual measurements is comparable to interobserver variability, indicating that clinical implementation of the tool is feasible.


Assuntos
Implante Coclear , Implantes Cocleares , Humanos , Estudos Retrospectivos , Radiografia , Cóclea/cirurgia
3.
Hear Res ; 432: 108741, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36972636

RESUMO

Performing simulations with a realistic biophysical auditory nerve fiber model can be very time-consuming, due to the complex nature of the calculations involved. Here, a surrogate (approximate) model of such an auditory nerve fiber model was developed using machine learning methods, to perform simulations more efficiently. Several machine learning models were compared, of which a Convolutional Neural Network showed the best performance. In fact, the Convolutional Neural Network was able to emulate the behavior of the auditory nerve fiber model with extremely high similarity (R2>0.99), tested under a wide range of experimental conditions, whilst reducing the simulation time by five orders of magnitude. In addition, a method for randomly generating charge-balanced waveforms using hyperplane projection is introduced. In the second part of this paper, the Convolutional Neural Network surrogate model was used by an Evolutionary Algorithm to optimize the shape of the stimulus waveform in terms of energy efficiency. The resulting waveforms resemble a positive Gaussian-like peak, preceded by an elongated negative phase. When comparing the energy of the waveforms generated by the Evolutionary Algorithm with the commonly used square wave, energy decreases of 8%-45% were observed for different pulse durations. These results were validated with the original auditory nerve fiber model, which demonstrates that the proposed surrogate model can be used as its accurate and efficient replacement.


Assuntos
Implante Coclear , Implantes Cocleares , Estimulação Elétrica/métodos , Nervo Coclear/fisiologia , Aprendizado de Máquina
4.
Ear Hear ; 44(2): 276-286, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36253905

RESUMO

OBJECTIVES: Many studies have assessed the performance of individuals with cochlear implants (CIs) with electrically evoked compound action potentials (eCAPs). These eCAP-based studies have focused on the amplitude information of the response, without considering the temporal firing properties of the excited auditory nerve fibers (ANFs), such as neural latency and synchrony. These temporal features have been associated with neural health in animal studies and, consequently, could be of importance to clinical CI outcomes. With a deconvolution method, combined with a unitary response, the eCAP can be mathematically unraveled into the compound discharge latency distribution (CDLD). The CDLD reflects both the number and the temporal firing properties of excited ANFs. The present study aimed to determine to what extent the CDLD derived from intraoperatively recorded eCAPs is related to speech perception in individuals with CIs. DESIGN: This retrospective study acquired data on monosyllabic word recognition scores and intraoperative eCAP amplitude growth functions from 124 adult patients with postlingual deafness that received the Advanced Bionics HiRes 90K device. The CDLD was determined for each recorded eCAP waveform by deconvolution. Each of the two Gaussian components of the CDLD was described by three parameters: the amplitude, the firing latency (the average latency of each component of the CDLD), and the variance of the CDLD components (an indication of the synchronicity of excited ANFs). Apart from these six CDLD parameters, the area under the CDLD curve (AUCD) and the slope of the AUCD growth function were determined as well. The AUCD was indicative of the total number of excited ANFs over time. The slope of the AUCD growth function indicated the increases in the number of excited ANFs with stimulus level. Associations between speech perception and each of these eight CDLD-related parameters were investigated with linear mixed modeling. RESULTS: In individuals with CIs, larger amplitudes of the two CDLD components, greater AUCD, and steeper slopes of the AUCD growth function were all significantly associated with better speech perception. In addition, a smaller latency variance in the early CDLD component, but not in the late, was significantly associated with better speech recognition scores. Speech recognition was not significantly dependent on CDLD latencies. The AUCD and the slope of the AUCD growth function provided a similar explanation of the variance in speech perception (R 2 ) as the eCAP amplitude, the slope of the amplitude growth function, the amplitude, and variance of the first CDLD component. CONCLUSION: The results demonstrate that both the number and the neural synchrony of excited ANFs, as revealed by CDLDs, are indicative of postimplantation speech perception in individuals with a CI. Because the CDLD-based parameters yielded a higher significance than the eCAP amplitude or the AGF slope, the authors conclude that CDLDs can serve as a clinical predictor of the survival of ANFs and that they have predictive value for postoperative speech perception performance. Thus, it would be worthwhile to incorporate the CDLD into eCAP measures in future clinical applications.


Assuntos
Implante Coclear , Implantes Cocleares , Percepção da Fala , Potenciais de Ação/fisiologia , Percepção da Fala/fisiologia , Estudos Retrospectivos , Potenciais Evocados Auditivos/fisiologia , Implante Coclear/métodos , Potenciais Evocados , Estimulação Elétrica , Nervo Coclear
5.
Int J Audiol ; 62(10): 992-1001, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-35875843

RESUMO

OBJECTIVE: We sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch discrimination and speech perception. DESIGN: In two tests, participants identified one stimulus (probe) as the odd-one-out compared with two reference stimuli. Probe stimuli were evoked using dual electrode stimulation characterised by the current steering coefficient α. The first test measured psychometric functions (PFs) on pre-defined contacts, with just a noticeable difference (JNDα) as the outcome variable. The second test estimated channel discrimination on the full electrode array, yielding a discrimination score of Dα. We measured speech perception as free-field consonant-vowel-consonant phoneme recognition scores. STUDY SAMPLE: We included 25 adults with at least 6 months of CI experience. RESULTS: JNDα and Dα scores measured on the same contact correlated significantly (rs = 0.64, p < 0.001). Mean JNDα and speech perception scores showed significant relationships in quiet and in noise. CONCLUSIONS: Dα correlated strongly with JNDα scores obtained with the PFs. For poor performers, the full-array test may underestimate JNDα. The full-array pitch discrimination test could be a helpful clinical tool, such as for fitting regions of lesser pitch discrimination ability.


Assuntos
Implante Coclear , Implantes Cocleares , Percepção da Fala , Adulto , Humanos , Discriminação da Altura Tonal , Ruído , Percepção da Fala/fisiologia
6.
Int J Audiol ; 62(10): 983-991, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-35997570

RESUMO

OBJECTIVES: We examined which preoperative diagnostic measure is most suited to serve as a selection criterion to determine adult cochlear implantation (CI) candidacy. DESIGN: Preoperative diagnostic measures included pure tone audiometry (PTA; 0.5, 1, 2, 4 kHz), speech perception tests (SPT) unaided with headphones and with best-aided hearing aids (in quiet and in noise). Gain in speech perception was used as outcome measure. Performance of preoperative measures was analysed using the area under the curve (AUC) of receiver operating characteristic (ROC) curves. STUDY SAMPLE: This retrospective longitudinal cohort study included 552 post-lingually deafened adults with CI in a tertiary referral centre in the Netherlands. RESULTS: Best-aided SPT in quiet was the most accurate in defining which CI candidates improved their speech perception in quiet postoperatively. For an improvement in speech perception in noise, the best-aided SPT in noise was the most accurate in defining which adult would benefit from CI. PTA measures performed lower compared to the SPT measures. CONCLUSIONS: SPT is better than PTA for selecting CI candidates who will benefit in terms of speech perception. Best-aided SPT in noise was the most accurate for indicating an improvement of speech perception in noise but was only evaluated in high performers with residual hearing. These insights will assist in formulating more effective selection criteria for CI.


Assuntos
Implante Coclear , Implantes Cocleares , Percepção da Fala , Adulto , Humanos , Estudos Longitudinais , Estudos Retrospectivos , Audiometria de Tons Puros , Resultado do Tratamento
7.
Hear Res ; 420: 108522, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35617925

RESUMO

BACKGROUND: The refractory recovery function (RRF) measures the electrically evoked compound action potential (eCAP) in response to a second pulse (probe) after masking by a first pulse (masker). This RRF is usually used to assess the refractory properties of the electrically stimulated auditory nerve (AN) by recording the eCAP amplitude as a function of the masker probe interval. Instead of assessing eCAP amplitudes only, recorded waveforms can also be described as a combination of a short-latency component (S-eCAP) and a long-latency component (L-eCAP). It has been suggested that these two components originate from two different AN fiber populations with differing refractory properties. The main objective of this study was to explore whether the refractory characteristics revealed by S-eCAP, L-eCAP, and the raw eCAP (R-eCAP) differ from each other. For clinical relevance, we compared these refractory properties between children and adults and examined whether they are related to cochlear implant (CI) outcomes. DESIGN: In this retrospective study, the raw RRF (R-RRF) was obtained from 121 Hi-Focus Mid-Scala or 1 J cochlear implant (Advanced Bionics, Valencia, CA) recipients. Each R-eCAP of the R-RRF was split into an S-eCAP and an L-eCAP using deconvolution to produce two new RRFs: S-RRF and L-RRF. The refractory properties were characterized by fitting an exponential decay function with three parameters: the absolute refractory period (T); the saturation level (A); and the speed of recovery from nerve refractoriness (τ), i.e., a measure of the relative refractory period. We compared the parameters of the R-RRF (RT, RA, Rτ) with those obtained from the S-RRF (ST, SA, Sτ) and L-RRF (LT, LA, Lτ) and investigated whether these parameters differed between children and adults. In addition, we examined the associations between these parameters and speech perception in adults with CI. Linear mixed modeling was used for the analyses. RESULTS: We found that TR was significantly longer than ST and LT, and ST was significantly longer than LT. RA was significantly larger than SA and LA, and SA was significantly larger than LA. Also, Sτ was significantly longer in comparison to Rτ and Lτ, but no significant difference was found between Rτ and Lτ. Children presented a significantly larger SA and LA and a shorter RT in comparison to adults. Shorter Sτ was significantly associated with better speech perception in adult CI recipients, but other parameters were not. CONCLUSION: We demonstrated that the two components of the eCAP have different refractory properties and that these also differ from those of the R-eCAP. In comparison with the R-eCAP, the refractory properties derived from the S-eCAP and L-eCAP can reveal additional clinical implications in terms of the refractory difference between children and adults as well as speech performance after implantation. Thus, it is worthwhile considering the two components of the eCAP in the future when assessing the clinical value of the auditory refractory properties.


Assuntos
Implante Coclear , Implantes Cocleares , Potenciais de Ação/fisiologia , Adulto , Criança , Nervo Coclear , Humanos , Estudos Retrospectivos
8.
Hear Res ; 420: 108490, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35395510

RESUMO

OBJECTIVE: Spread of excitation (SOE) in cochlear implants (CI) is a measure linked to the specificity of the electrode-neuron interface. The SOE can be estimated objectively by electrically evoked compound action potential (eCAP) measurements, recorded with the forward-masking paradigm in CI recipients. The eCAP amplitude can be plotted as a function of the roving masker, resulting in a spatial forward masking (SFM) curve. The eCAP amplitudes presented in the SFM curves, however, reflect an interaction between a masker and probe stimulus, making the SFM curves less reliable for examining SOE effects at the level of individual electrode contacts. To counter this, our previously published deconvolution method estimates the SOE at the electrode level by deconvolving the SFM curves (Biesheuvel et al., 2016). The aim of this study was to investigate the effect of stimulus level on the SOE of individual electrode contacts by using SFM curves analyzed with our deconvolution method. DESIGN: Following the deconvolution method, theoretical SFM curves were calculated by the convolution of parameterized excitation density profiles (EDP) attributable to masker and probe stimuli. These SFM curves were subsequently fitted to SFM curves from CI recipients by iteratively adjusting the EDPs. We first improved the EDP parameterization to account for stimulus-level effects and validated this updated parameterization by comparing the EDPs to simulated excitation density profiles (sEDP) from our computational model of the human cochlea. Secondly, we analyzed SFM curves recorded with varying probe stimulus level in 24 patients, all implanted with a HiFocus Mid-Scala electrode array. With the deconvolution method extended to account for stimulus level effects, the SFM curves measured with varying probe stimulus levels were converted into EDPs to elucidate the effects of stimulus level on the SOE. RESULTS: The updated EDP parameterization was in good agreement with the sEDPs from the computational model. Using the extended deconvolution method, we found that higher stimulus levels caused significant widening of EDPs (p < 0.001). The stimulus level also affected the EDP amplitude (p < 0.001) and the center of excitation (p < 0.05). Concerning the raw SFM curves, an increase in current level led to higher SFM curve amplitudes (p < 0.001), while the width of the SFM curves did not change significantly (p = 0.62). CONCLUSION: The extended deconvolution method enabled us to study the effect of stimulus level on excitation areas in an objective way, as the EDP parameterization was in good agreement with sEDPs from our computational model. The analysis of SFM curves provided new insights into the effect of the stimulus level on SOE. We found that the EDPs, and therefore the SOE, mainly became wider when the stimulus level increased. Lastly, the comparison of the EDP parameterization with simulations in our computation model provided new insights about the validity of the deconvolution method.


Assuntos
Implante Coclear , Implantes Cocleares , Potenciais de Ação/fisiologia , Cóclea/fisiologia , Implante Coclear/métodos , Estimulação Elétrica , Potenciais Evocados Auditivos , Humanos
9.
Otol Neurotol ; 43(4): e427-e434, 2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-35213473

RESUMO

HYPOTHESIS: Insertion speed during cochlear implantation determines the risk of cochlear trauma. By slowing down insertion speed tactile feedback is improved. This is highly conducive to control the course of the electrode array along the cochlear contour and prevent translocation from the scala tympani to the scala vestibuli. BACKGROUND: Limiting insertion trauma is a dedicated goal in cochlear implantation to maintain the most favorable situation for electrical stimulation of the remaining stimulable neural components of the cochlea. Surgical technique is one of the potential influencers on translocation behavior of the electrode array. METHODS: The intrascalar position of 226 patients, all implanted with a precurved electrode array, aiming a mid-scalar position, was evaluated. One group (n = 113) represented implantation with an insertion time less than 25 seconds (fast insertion) and the other group (n = 113) was implanted in 25 or more seconds (slow insertion). A logistic regression analysis studied the effect of insertion speed on insertion trauma, controlled for surgical approach, cochlear size, and angular insertion depth. Furthermore, the effect of translocation on speech performance was evaluated using a linear mixed model. RESULTS: The translocation rate within the fast and slow insertion groups were respectively 27 and 10%. A logistic regression analysis showed that the odds of dislocation increases by 2.527 times with a fast insertion, controlled for surgical approach, cochlear size, and angular insertion depth (95% CI = 1.135, 5.625). We failed to find a difference in speech recognition between patients with and without translocated electrode arrays. CONCLUSION: Slowing down insertion speed till 25 seconds or longer reduces the incidence of translocation.


Assuntos
Implante Coclear , Implantes Cocleares , Cóclea/cirurgia , Implante Coclear/métodos , Eletrodos Implantados , Humanos , Rampa do Tímpano/cirurgia , Rampa do Vestíbulo/cirurgia
10.
Audiol Neurootol ; 27(1): 75-82, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-33849023

RESUMO

INTRODUCTION: Contralateral routing of signals (CROS) can be used to eliminate the head shadow effect. In unilateral cochlear implant (CI) users, CROS can be achieved with placement of a microphone on the contralateral ear, with the signal streamed to the CI ear. CROS was originally developed for unilateral CI users without any residual hearing in the nonimplanted ear. However, the criteria for implantation are becoming progressively looser, and the nonimplanted ear can have substantial residual hearing. In this study, we assessed how residual hearing in the contralateral ear influences CROS effectiveness in unilateral CI users. METHODS: In a group of unilateral CI users (N = 17) with varying amounts of residual hearing, we deployed free-field speech tests to determine the effects of CROS on the speech reception threshold (SRT) in amplitude-modulated noise. We compared 2 spatial configurations: (1) speech presented to the CROS ear and noise to the CI ear (SCROSNCI) and (2) the reverse (SCINCROS). RESULTS: Compared with the use of CI only, CROS improved the SRT by 6.4 dB on average in the SCROSNCI configuration. In the SCINCROS configuration, however, CROS deteriorated the SRT by 8.4 dB. The benefit and disadvantage of CROS both decreased significantly with the amount of residual hearing. CONCLUSION: CROS users need careful instructions about the potential disadvantage when listening in conditions where the CROS ear mainly receives noise, especially if they have residual hearing in the contralateral ear. The CROS device should be turned off when it is on the noise side (SCINCROS). CI users with residual hearing in the CROS ear also should understand that contralateral amplification (i.e., a bimodal hearing solution) will yield better results than a CROS device. Unilateral CI users with no functional contralateral hearing should be considered the primary target population for a CROS device.


Assuntos
Implante Coclear , Implantes Cocleares , Auxiliares de Audição , Localização de Som , Percepção da Fala , Progressão da Doença , Audição , Humanos
11.
Hear Res ; 415: 108413, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34952734

RESUMO

The main aim of this computational modelling study was to test the validity of the hypothesis that sensitivity to the polarity of cochlear implant stimulation can be interpreted as a measure of neural health. For this purpose, the effects of stimulus polarity on neural excitation patterns were investigated in a volume conduction model of the implanted human cochlea, which was coupled with a deterministic active nerve fibre model based on characteristics of human auditory neurons. The nerve fibres were modelled in three stages of neural degeneration: intact, with shortened peripheral terminal nodes and with complete loss of the peripheral processes. The model simulated neural responses to monophasic, biphasic, triphasic and pseudomonophasic pulses of both polarities. Polarity sensitivity was quantified as the so-called polarity effect (PE), which is defined as the dB difference between cathodic and anodic thresholds. Results showed that anodic pulses mostly excited the auditory neurons in their central axons, while cathodic stimuli generally excited neurons in their peripheral processes or near their cell bodies. As a consequence, cathodic thresholds were more affected by neural degeneration than anodic thresholds. Neural degeneration did not have a consistent effect on the modelled PE values, though there were notable effects of electrode contact insertion angle and distance from the modiolus. Furthermore, determining PE values using charge-balanced multiphasic pulses as approximations of monophasic stimuli produced different results than those obtained with true monophasic pulses, at a degree that depended on the specific pulse shape; in general, pulses with lower secondary phase amplitudes showed polarity sensitivities closer to those obtained with true monophasic pulses. The main conclusion of this study is that polarity sensitivity is not a reliable indicator of neural health; neural degeneration affects simulated polarity sensitivity, but its effect is not consistently related to the degree of degeneration. Polarity sensitivity is not simply a product of the state of the neurons, but also depends on spatial factors.


Assuntos
Implante Coclear , Implantes Cocleares , Axônios , Cóclea/fisiologia , Nervo Coclear/fisiologia , Estimulação Elétrica , Humanos
12.
MethodsX ; 8: 101240, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34434763

RESUMO

The electrically evoked compound action potential (eCAP) has been widely studied for its clinical value for the evaluation of the surviving auditory nerve (AN) cells. However, many unknowns remain about the temporal firing properties of the AN fibers that underlie the eCAP in CI recipients. These temporal properties may contain valuable information about the condition of the AN. Here, we propose an iterative deconvolution model for estimating the human evoked unitary response (UR) and for extracting the compound discharge latency distribution (CDLD) from eCAP recordings, under the assumption that all AN fibers have the same UR. In this model, an eCAP is modeled by convolving a parameterized UR and a parameterized CDLD model. Both the UR and CDLD are optimized with an iterative deconvolution fitting error minimization routine to minimize the error between the modeled eCAP and the recorded eCAP.•This method first estimates the human UR from eCAP recordings. The human eCAP is unknown at the time of this writing. The UR is subsequently used to extract the underlying temporal neural excitation pattern (the CDLD) that reflects the contributions from individual AN fibers in human eCAPs.•By calculating the CDLD, the synchronicity of AN fibers can be evaluated.

13.
Front Neurol ; 12: 676812, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34262523

RESUMO

Objectives: Video head impulse test (v-HIT) is a quick, non-invasive and relatively cheap test to evaluate vestibular function compared to the caloric test. The latter is, however, needed to decide on the optimal side to perform cochlear implantation to avoid the risk on inducing a bilateral vestibular areflexia. This study evaluates the effectiveness of using the v-HIT to select cochlear implant (CI) candidates who require subsequent caloric testing before implantation, in that way reducing costs and patient burden at the same time. Study Design: Retrospective study using clinical data from 83 adult CI-candidates, between 2015 and 2020 at the Leiden University Medical Center. Materials and Methods: We used the v-HIT mean gain, MinGain_LR, the gain asymmetry (GA) and a newly defined parameter, MGS (Minimal Gain & Saccades) as different models to detect the group of patients that would need the caloric test to decide on the ear of implantation. The continuous model MGS was defined as the MinGain_LR, except for the cases with normal gain (both sides ≥0.8) where no corrective saccades were present. In the latter case MGS was defined to be 1.0 (the ideal gain value). Results: The receiver operating characteristics curve showed a very good diagnostic accuracy with and area under the curve (AUC) of 0.81 for the model MGS. The v-HIT mean gain, the minimal gain and GA had a lower diagnostic capacity with an AUC of 0.70, 0.72, and 0.73, respectively. Using MGS, caloric testing could be avoided in 38 cases (a reduction of 46%), with a test sensitivity of 0.9 (i.e., missing 3 of 28 cases). Conclusions: The newly developed model MGS balances the sensitivity and specificity of the v-HIT better than the more commonly evaluated parameters such as mean gain, MinGain_LR and GA. Therefore, taking the presence of corrective saccades into account in the evaluation of the v-HIT gain can considerably reduce the proportion of CI-candidates requiring additional caloric testing.

14.
Ear Hear ; 42(5): 1397-1404, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33974777

RESUMO

OBJECTIVES: Misplacement of the electrode array is associated with impaired speech perception in patients with cochlear implants (CIs). Translocation of the electrode array is the most common misplacement. When a CI is translocated, it crosses the basilar membrane from the scala tympani into the scala vestibuli. The position of the implant can be determined on a postoperative CT scan. However, such a scan is not obtained routinely after CI insertion in many hospitals, due to radiation exposure and processing time. Previous studies have shown that impedance measures might provide information on the placement of the electrode arrays. The electrode impedance was measured by dividing the plateau voltage at the end of the first phase of the pulse by the injected current. The access resistance was calculated using the so-called access voltage at the first sampled time point after the start of the pulse divided by the injected current. In our study, we obtained the electrode impedance and the access resistance to detect electrode translocations using electrical field imaging. We have investigated how reliably these two measurements can detect electrode translocation, and which method performed best. DESIGN: We calculated the electrode impedances and access resistances using electrical field imaging recordings from 100 HiFocus Mid-Scala CI (Advanced Bionics, Sylmar, CA) recipients. We estimated the normal values of these two measurements as the baselines of the implant placed in the cochlea without translocation. Next, we calculated the maximal electrode impedance deviation and the maximal access-resistance deviation from the respective baselines as predictors of translocation. We classified these two predictors as translocations or nontranslocations based on the bootstrap sampling method and receiver operating characteristics curves analysis. The accuracy could be calculated by comparing those predictive results to a gold standard, namely the clinical CT scans. To determine which measurement more accurately detected translocation, the difference between the accuracies of the two measurements was calculated. RESULTS: Using the bootstrap sampling method and receiver operating characteristics-based optimized threshold criteria, the 95% confidence intervals of the accuracies of translocation detections ranged from 77.8% to 82.1% and from 89.5% to 91.2% for the electrode impedance and access resistance, respectively. The accuracies of the maximal access-resistance deviations were significantly larger than that of the maximal electrode impedance deviations. The location of the translocation as predicted by the access resistance was significantly correlated with the result derived from the CT scans. In contrast, no significant correlation was observed for the electrode impedance. CONCLUSIONS: Both the electrode impedance and access resistance proved reliable metrics to detect translocations for HiFocus Mid-Scala electrode arrays. The access resistance had, however, significantly better accuracy and it also reliably detected the electrode-location of translocations. The electrode impedance did not correlate significantly with the location of translocation. Measuring the access resistance is, therefore, the recommended method to detect electrode-array translocations. These measures can provide prompt feedback for surgeons after insertion, improving their surgical skills, and ultimately reducing the number of translocations. In the future, such measurements may allow near-real-time monitoring of the electrode array during insertion, helping to avoid translocations.


Assuntos
Implante Coclear , Implantes Cocleares , Cóclea/diagnóstico por imagem , Cóclea/cirurgia , Impedância Elétrica , Humanos , Rampa do Tímpano
15.
Ear Hear ; 42(6): 1602-1614, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33974780

RESUMO

OBJECTIVES: Speech understanding in noise is difficult for patients with a cochlear implant. One common and disruptive type of noise is transient noise. We have tested transient noise reduction (TNR) algorithms in cochlear implant users to investigate the merits of personalizing the noise reduction settings based on a subject's own preference. DESIGN: The effect of personalizing two parameters of a broadband and a multiband TNR algorithm (TNRbb and TNRmb, respectively) on speech recognition was tested in a group of 15 unilaterally implanted subjects in cafeteria noise. The noise consisted of a combination of clattering dishes and babble noise. Each participant could individually vary two parameters, namely the scaling factor of the attenuation and the release time (τ). The parameter τ represents the duration of the attenuation applied after a transient is detected. As a reference, the current clinical standard TNR "SoundRelax" from Advanced Bionics was tested (TNRbb-std). Effectiveness of the algorithms on speech recognition was evaluated adaptively by determining the speech reception threshold (SRT). Possible subjective benefits of the algorithms were assessed using a rating task at a fixed signal-to-noise ratio (SNR) of SRT + 3 dB. Rating was performed on four items, namely speech intelligibility, speech naturalness, listening effort, and annoyance of the noise. Word correct scores were determined at these fixed speech levels as well. RESULTS: The personalized TNRmb improved the SRT statistically significantly with 1.3 dB, while the personalized TNRbb degraded it significantly by 1.7 dB. For TNRmb, we attempted to further optimize its settings by determining a group-based setting, leaving out those subjects that did not experience a benefit from it. Using these group-based settings, however, TNRmb did not have a significant effect on the SRT any longer. TNRbb-std did not affect speech recognition significantly. No significant effects on subjective ratings were found for any of the items investigated. In addition, at a constant speech level of SRT + 3 dB, no effect of any of the algorithms was found on word correct scores, including TNRmb with personalized settings. CONCLUSIONS: Our study results indicate that personalizing noise reduction settings of a multiband TNR algorithm can significantly improve speech intelligibility in transient noise, but only under challenging listening conditions around the SRT. At more favorable SNRs (SRT + 3 dB), this benefit was lost. We hypothesize that TNRmb was beneficial at lower SNRs, because of more effective artifact detection under those conditions. Group-averaged settings of the multiband algorithm did not significantly affect speech recognition. TNRbb decreased speech recognition significantly using personalized parameter settings. Rating scores were not significantly affected by the algorithms under any condition tested. The currently available TNR algorithm for Advanced Bionics systems (SoundRelax) is a broadband filter that does not support personalization of its settings. Future iterations of this algorithm might benefit from upgrading it to a multiband variant with the option to personalize its parameter settings.


Assuntos
Implante Coclear , Implantes Cocleares , Infecções Sexualmente Transmissíveis , Percepção da Fala , Algoritmos , Implante Coclear/métodos , Humanos , Inteligibilidade da Fala
16.
J Deaf Stud Deaf Educ ; 26(3): 405-416, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-33866374

RESUMO

Children with hearing loss (HL) are at risk for a lower educational achievement. This longitudinal study compared the school career of a nationwide Dutch cohort with and without HL based on descriptive data of the governmental authority Statistics Netherlands. From 2008 to 2018, 3,367,129 children, of whom 1,193 used cochlear implants (CIs) and 8,874 used hearing aids (HAs), were attending primary and/or secondary education. Sixty-one percent of children with HL attended mainstream and 31% special primary education. Compared to mainstreamed pupils without HL, mainstreamed pupils with HL achieved lower levels for language and mathematics in primary education but eventually attended comparable types of secondary education. Children with HL attending special primary education attained lower types of secondary education compared to mainstreamed peers with and without HL. These findings suggest that future educational (and as a result professional) attainment of a child with HL depends on the type of primary educational setting.


Assuntos
Implantes Cocleares , Surdez , Perda Auditiva , Criança , Humanos , Estudos Longitudinais , Instituições Acadêmicas
17.
PLoS One ; 16(3): e0248546, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33690697

RESUMO

[This corrects the article DOI: 10.1371/journal.pone.0124102.].

18.
Ear Hear ; 42(5): 1338-1350, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33675588

RESUMO

OBJECTIVES: While the costs and outcomes of cochlear implantation (CI) have been widely assessed, most of these analyses were solely performed from the perspective of healthcare costs. This study assesses the costs and benefits of CI in the Netherlands from a broader societal perspective, including health outcomes, healthcare cost, educational cost, and productivity losses and gains. DESIGN: The cost and benefits of CI were analyzed in this cost-benefit analysis, in which a monetary value is put on both the resources needed and the outcomes of CI. The costs and benefits were analyzed by prototypical instances of three groups, representing the majority of cochlear implant patients: prelingually deaf children implanted at the age of 1, adults with progressive profound hearing loss implanted at the age of 40 and seniors implanted at the age of 70 with progressive profound hearing loss. Costs and benefits were estimated over the expected lifetimes of the members of each group, using a Markov state transition model. Model parameters and assumptions were based on published literature. Probabilistic and one-way sensitivity analyses were performed. RESULTS: In all three patient groups, the total benefits of CI exceeded the total cost, leading to a net benefit of CI. Prelingually deaf children with a bilateral CI had a lifetime positive outcome net benefit of €433,000. Adults and seniors with progressive profound hearing loss and a unilateral CI had a total net benefit of €275,000 and €76,000, respectively. These results ensue from health outcomes expressed in monetary terms, reduced educational cost, and increased productivity. CONCLUSIONS: Based on estimates from modeling, the increased healthcare costs due to CI were more than compensated by the value of the health benefits and by savings in educational and productivity costs. In particular, for children and working adults, the societal benefit was positive even without taking health benefits into account. Therefore, CI generates an advantage for both patients and society.


Assuntos
Implante Coclear , Implantes Cocleares , Adulto , Criança , Análise Custo-Benefício , Custos de Cuidados de Saúde , Humanos , Anos de Vida Ajustados por Qualidade de Vida
19.
Ear Hear ; 42(4): 949-960, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33480623

RESUMO

OBJECTIVES: The primary objective of this study is to identify the biographic, audiologic, and electrode position factors that influence speech perception performance in adult cochlear implant (CI) recipients implanted with a device from a single manufacturer. The secondary objective is to investigate the independent association of the type of electrode (precurved or straight) with speech perception. DESIGN: In a cross-sectional study design, speech perception measures and ultrahigh-resolution computed tomography scans were performed in 129 experienced CI recipients with a postlingual onset of hearing loss. Data were collected between December 2016 and January 2018 in the Radboud University Medical Center, Nijmegen, the Netherlands. The participants received either a precurved electrode (N = 85) or a straight electrode (N = 44), all from the same manufacturer. The biographic variables evaluated were age at implantation, level of education, and years of hearing loss. The audiometric factors explored were preoperative and postoperative pure-tone average residual hearing and preoperative speech perception score. The electrode position factors analyzed, as measured from images obtained with the ultrahigh-resolution computed tomography scan, were the scalar location, angular insertion depth of the basal and apical electrode contacts, and the wrapping factor (i.e., electrode-to-modiolus distance), as well as the type of electrode used. These 11 variables were tested for their effect on three speech perception outcomes: consonant-vowel-consonant words in quiet tests at 50 dB SPL (CVC50) and 65 dB SPL (CVC65), and the digits-in-noise test. RESULTS: A lower age at implantation was correlated with a higher CVC50 phoneme score in the straight electrode group. Other biographic variables did not correlate with speech perception. Furthermore, participants implanted with a precurved electrode and who had poor preoperative hearing thresholds performed better in all speech perception outcomes than the participants implanted with a straight electrode and relatively better preoperative hearing thresholds. After correcting for biographic factors, audiometric variables, and scalar location, we showed that the precurved electrode led to an 11.8 percentage points (95% confidence interval: 1.4-20.4%; p = 0.03) higher perception score for the CVC50 phonemes compared with the straight electrode. Furthermore, contrary to our initial expectations, the preservation of residual hearing with the straight electrode was poor, as the median preoperative and the postoperative residual hearing thresholds for the straight electrode were 88 and 122 dB, respectively. CONCLUSIONS: Cochlear implantation with a precurved electrode results in a significantly higher speech perception outcome, independent of biographic factors, audiometric factors, and scalar location.


Assuntos
Implante Coclear , Implantes Cocleares , Percepção da Fala , Adulto , Estudos Transversais , Humanos , Resultado do Tratamento
20.
Ear Hear ; 42(1): 68-75, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32590629

RESUMO

OBJECTIVES: The impact of the newly introduced cochlear implantation criteria of the United Kingdom and Flanders (Dutch speaking part of Belgium) was examined in the patient population of a tertiary referral center in the Netherlands. We compared the patients who would be included/excluded under the new versus old criteria in relation to the actual improvement in speech understanding after implantation in our center. We also performed a sensitivity analysis to examine the effectiveness of the different preoperative assessment approaches used in the United Kingdom and Flanders. DESIGN: The selection criteria were based on preoperative pure-tone audiometry at 0.5, 1, 2, and 4 kHz and a speech perception test (SPT) with and without best-aided hearing aids. Postoperatively, the same SPT was conducted to assess the benefit in speech understanding. RESULTS: The newly introduced criteria in Flanders and the United Kingdom were less restrictive, resulting in greater percentages of patients implanted with CI (increase of 30%), and sensitivity increase of 31%. The preoperative best-aided SPT, used by both countries, had the highest diagnostic ability to indicate a postoperative improvement of speech understanding. We observed that patient selection was previously dominated by the pure-tone audiometry criteria in both countries, whereas speech understanding became more important in their new criteria. Among patients excluded by the new criteria, seven of eight (the United Kingdom and Flanders) did exhibit improved postoperative speech understanding. CONCLUSIONS: The new selection criteria of the United Kingdom and Flanders led to increased numbers of postlingually deafened adults benefitting from CI. The new British and Flemish criteria depended on the best-aided SPT with the highest diagnostic ability. Notably, the new criteria still led to the rejection of candidates who would be expected to gain considerably in speech understanding after implantation.


Assuntos
Implante Coclear , Implantes Cocleares , Percepção da Fala , Adulto , Bélgica , Humanos , Países Baixos , Seleção de Pacientes , Estudos Retrospectivos , Resultado do Tratamento , Reino Unido
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