<b>Clinical use of a system for the automated recording and analysis of electrically evoked compound action potentials (ECAPs) in cochlear implant patients</b>

Gärtner, Lutz; Lenarz, Thomas; Joseph, G.; Büchner, Andreas

doi:10.3109/00016480903380539

Cited by 21 publications

(15 citation statements)

References 19 publications

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“…Second, as the minimum age for implantation continues to decrease while the inclusion criteria continue to expand, the psychophysical test may be challenging or even impossible for the pediatric and expanded populations. The objective physiological measure is relatively reliable, fast and requires no subjective responses, which makes it useful to not only predict threshold and maximal loudness, but also spatial selectivity in cochlear implants (e.g., Eisen et al, 2004; Gartner et al, 2010). Combining these physiological measures could allow efficient and effective fitting of the cochlear implant and improve its overall performance.…”

Section: Discussionmentioning

confidence: 99%

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation

et al. 2012

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Sharp spatial selectivity is critical to auditory performance, particularly in pitch related tasks. Most contemporary cochlear implants have employed monopolar stimulation that produces broad electric fields, which presumably contribute to poor pitch and pitch-related performance by implant users. Bipolar or tripolar stimulation can generate focused electric fields but requires higher current to reach threshold and, more interestingly, has not produced any apparent improvement in cochlear implant performance. The present study addressed this dilemma by measuring psychophysical and physiological spatial selectivity with both broad and focused stimulations in the same cohort of subjects. Different current levels were adjusted by systematically measuring loudness growth for each stimulus, each stimulation mode, and in each subject. Both psychophysical and physiological measures showed that, although focused stimulation produced significantly sharper spatial tuning than monopolar stimulation, it could shift the tuning position or even split the tuning tips. The altered tuning with focused stimulation is interpreted as a result of poor electrode-to-neuron interface in the cochlea, and is suggested to be mainly responsible for the lack of consistent improvement in implant performance. A linear model could satisfactorily quantify the psychophysical and physiological data and derive the tuning width. Significant correlation was found between the individual physiological and psychophysical tuning widths, and the correlation was improved by log-linearly transforming the physiological data to predict the psychophysical data. Because the physiological measure took only one-tenth of the time of the psychophysical measure, the present model is of high clinical significance in terms of predicting and improving cochlear implant performance.

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Section: Discussionmentioning

confidence: 99%

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation

et al. 2012

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“…We envisage a closed-loop CI which can automatically accesses and analyze neural responses from multiple levels in the auditory neural pathway. First, the ECAP and EABR responses [20], [64] could be used in a closed-loop CI to automatically set the comfort and threshold levels, eliminating a tedious job for the audiologist [17]. However, further work is still needed to find a completely automated and method of estimating behavioral thresholds from ECAP and EABR responses.…”

Section: B Applications For the Eer Techniquementioning

confidence: 99%

“…To design a completely closed-loop CI system it would be necessary to record and analyze EP responses automatically. Recently, an important study [17] has shown that automated collection and analysis of ECAP responses is feasible, reliable and repeatable. We envisage a closed-loop CI which can automatically accesses and analyze neural responses from multiple levels in the auditory neural pathway.…”

Section: B Applications For the Eer Techniquementioning

confidence: 99%

“…A number of techniques for separating the artifact from ECAP response have been developed and are discussed in Section III. CI manufacturers have implemented and automated these methods [17], making the recording of ECAPs in the clinic relatively straightforward with no additional conventional EP equipment required. The commercialization of these techniques mean that ECAPs are the most widely used objective measure by audiologists working with CI patients.…”

Section: A Auditory Nervementioning

confidence: 99%

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Towards a Closed-Loop Cochlear Implant System: Application of Embedded Monitoring of Peripheral and Central Neural Activity

McLaughlin

Dimitrijevic

et al. 2012

IEEE Trans. Neural Syst. Rehabil. Eng.

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Although the cochlear implant (CI) is widely considered the most successful neural prosthesis, it is essentially an open-loop system that requires extensive initial fitting and frequent tuning to maintain a high, but not necessarily optimal, level of performance. Two developments in neuroscience and neuroengineering now make it feasible to design a closed-loop CI. One development is the recording and interpretation of evoked potentials (EPs) from the peripheral to the central nervous system. The other is the embedded hardware and software of a modern CI that allows recording of EPs. We review EPs that are pertinent to behavioral functions from simple signal detection and loudness growth to speech discrimination and recognition. We also describe signal processing algorithms used for electric artifact reduction and cancellation, critical to the recording of electric EPs. We then present a conceptual design for a closed-loop CI that utilizes in an innovative way the embedded implant receiver and stimulators to record short latency compound action potentials ( ~1 ms), auditory brainstem responses (1-10 ms) and mid-to-late cortical potentials (20-300 ms). We compare EPs recorded using the CI to EPs obtained using standard scalp electrodes recording techniques. Future applications and capabilities are discussed in terms of the development of a new generation of closed-loop CIs and other neural prostheses.

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“…In this way, verification of an auditory response is obtained as well as some level of confirmation of device function, and response characteristics can be useful in the setting of processor fitting parameters, particularly in young children who are unable to provide reliable behavioural responses [6,16]. Because of the evolved state of this method and its automatic determination of the neural responses [18], the method has gained broad clinical application in this patient group. In addition, eCAP measures are able to identify certain electrode anomalies, although the amount of direct information is limited.…”

Section: Introductionmentioning

confidence: 99%

The Intra-Cochlear Impedance-Matrix (IIM) test for the Nucleus® cochlear implant

Hey

Böhnke

Dillier

et al. 2015

Biomedical Engineering / Biomedizinische Technik

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Objective: To describe the principles and operation of a new telemetry-based function test for the Nucleus ® cochlear implant, known as the CS19 Intra-Cochlear Impedance Matrix (IIM) and to present results from a multicentre clinical study to establish reproducibility (test-retest reliability) and normative ranges. Method: The IIM test measures bipolar impedances between all electrode pairs and employs a normalization procedure based on common ground impedances in order to identify abnormal current paths among electrodes. Six European clinics collected IIM data from a total of 192 devices. Results: Reproducibility was high between initial and repeat measurements. The normative analysis demonstrated narrow ranges among devices after normalization of impedance data. The IIM is able to identify abnormal current paths that are not evident from standard impedance telemetry and may otherwise only be found utilising average electrode voltage measurements (AEV). Conclusions:The IIM test was found to be straightforward to perform clinically and demonstrated reproducible data with narrow ranges in normally-functioning devices. Because this test uses a very low stimulation level the IIM test is well suited for children or multiply handicapped CI users who cannot reliably report on their auditory percepts. The new algorithms show potential to improve implant integrity testing capabilities if implemented in future clinical software.

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Clinical use of a system for the automated recording and analysis of electrically evoked compound action potentials (ECAPs) in cochlear implant patients

Abstract: The time required to determine a TECAP threshold for a single electrode contact was found to be between 0.5 and 1 min.

Cited by 21 publications

References 19 publications

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation

Towards a Closed-Loop Cochlear Implant System: Application of Embedded Monitoring of Peripheral and Central Neural Activity

The Intra-Cochlear Impedance-Matrix (IIM) test for the Nucleus® cochlear implant

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