scholarly journals Multistage nonlinear optimization to recover neural activation patterns from evoked compound action potentials of cochlear implant users

2015 ◽  
pp. 1-1 ◽  
Author(s):  
Stefano Cosentino ◽  
Etienne Gaudrain ◽  
John Deeks ◽  
Robert Carlyon
Keyword(s):  
Cochlear Implant ◽  
Nonlinear Optimization ◽  
Action Potentials ◽  
Neural Activation ◽  
Activation Patterns ◽  
Compound Action Potentials ◽  
Compound Action

scholarly journals SpeedCAP: An Efficient Method for Estimating Neural Activation Patterns Using Electrically-Evoked Compound Action-Potentials in Cochlear Implant Users

2021 ◽  
Author(s):  
Charlotte Garcia ◽  
John M. Deeks ◽  
Tobias Goehring ◽  
Daniele Borsetto ◽  
Manohar Bance ◽  
...  
Keyword(s):  
Data Collection ◽  
Cochlear Implant ◽  
Action Potentials ◽  
Forward Masking ◽  
Patient Specific ◽  
Neural Activation ◽  
Current Spread ◽  
Wide Range ◽  
Compound Action Potentials ◽  
Compound Action

Objectives: Electrically-Evoked Compound Action-Potentials (ECAPs) can be recorded using the electrodes in a cochlear implant (CI) and represent the synchronous responses of the electrically-stimulated auditory-nerve. ECAPs can be obtained using a forward-masking method that measures the neural response to a probe and masker electrode separately and in combination. The Panoramic ECAP (PECAP) method measures ECAPs using multiple combinations of masker and probe electrodes and uses a nonlinear optimization algorithm to estimate current spread from each electrode and neural health along the cochlea. However, the measurement of ECAPs from multiple combinations of electrodes is too time-consuming for use in clinics. This study proposes and evaluates a fast version of the PECAP measurements, SpeedCAP, that minimises recording time by exploiting redundancies between multiple ECAP measures, and that can be applied to methods where multiple ECAPs are required. Design: In the first study, 11 users of Cochlear Limited CIs took part. ECAPs were recorded using the forward-masking artefact-cancellation technique at the most comfortable loudness level (MCL) for every combination of masker and probe electrodes for all active electrodes in the users’ MAPs, as per the standard PECAP recording paradigm. The same current levels and recording parameters were then used to collect ECAPs in the same users with the SpeedCAP method. The ECAP amplitudes were then compared between the two conditions, as were the corresponding estimates of neural health and current spread calculated using the PECAP method described by Garcia et al (2021). The second study measured SpeedCAP intra-operatively in 8 CI patients and with all maskers and probes presented at the same current level to assess feasibility. ECAPs for the subset of conditions where the masker and probe were presented on the same electrode were compared to those obtained using the slower approach leveraged by the standard clinical software. Results: Data collection time was reduced from 45 (PECAP) to 8 (SpeedCAP) minutes. There were no significant differences between normalized root mean squared error (RMSE) repeatability metrics for post-operative PECAP and SpeedCAP data, nor for the RMSEs calculated between PECAP and SpeedCAP data. When between-participant differences were removed, both the neural health (r = 0.73) and current spread (r = 0.65) estimates were significantly correlated (p < 0.0001, df = 218) between SpeedCAP and PECAP conditions across all electrodes. Valid ECAPs were obtained in all patients in the second study, demonstrating intra-operative feasibility of SpeedCAP. No significant differences in RMSEs were detectable between post- and intra-operative ECAP measurements. Conclusions: The improved efficiency of SpeedCAP provides time savings facilitating multi-electrode ECAP recordings in routine clinical practice. The SpeedCAP data collection is sufficiently quick to record intra-operatively, and adds no significant error to the ECAP amplitudes. Such measurements could thereafter be submitted to models such as PECAP to provide patient-specific patterns of neural activation to inform programming of clinical MAPs and/or identify causes of poor performance at the electrode-nerve interface of CI users. The speed and accuracy of these measurements also opens up a wide range of additional research questions to be addressed.

Using Evoked Compound Action Potentials to Assess Activation of Electrodes and Predict C-Levels in the Tempo+ Cochlear Implant Speech Processor

2010 ◽  
Vol 31 (1) ◽  
pp. 134-145 ◽  
Author(s):  
Isaac Alvarez ◽  
Angel de la Torre ◽  
Manuel Sainz ◽  
Cristina Roldán ◽  
Hansjoerg Schoesser ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Action Potentials ◽  
Speech Processor ◽  
Compound Action Potentials ◽  
Compound Action

scholarly journals The Panoramic ECAP Method: estimating patient-specific patterns of current spread and neural health in cochlear implant users

2020 ◽  
Author(s):  
Charlotte Garcia ◽  
Tobias Goehring ◽  
Stefano Cosentino ◽  
Richard E Turner ◽  
John M. Deeks ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Significant Negative Correlation ◽  
Patient Specific ◽  
Clinical Settings ◽  
Neural Activation ◽  
Activation Patterns ◽  
Current Spread ◽  
Compound Action Potentials ◽  
In Cis

The knowledge of patient-specific neural excitation patterns from cochlear implants can provide important information for optimising efficacy and improving speech perception outcomes. The Panoramic ECAP (or ‘PECAP’) method (Cosentino, et al., 2015) uses forward-masked electrically evoked compound action potentials (ECAPs) to estimate neural activation patterns of cochlear implant (CI) stimulation. The algorithm requires ECAPs be measured for loudness-balanced stimuli from all combinations of probe and masker electrodes, and takes advantage of ECAP amplitudes being a result of the overlapping excitatory areas of both probes and maskers. Here we present an improved version of the PECAP algorithm that imposes biologically realistic constraints on the solution and produces separate estimates of current spread and neural health along the length of the electrode array. The algorithm was evaluated for reliability and accuracy in three ways: (1) computer-simulated current-spread and neural-health scenarios, (2) comparisons to psychophysical correlates of neural health and electrode-modiolus distances in human CI users, and (3) detection of simulated neural ‘dead’ regions (using forward masking) in human CI users. The PECAP algorithm reliably estimated the computer simulated scenarios. A moderate but significant negative correlation between focused thresholds and PECAP’s neural health estimates was found, consistent with previous literature. It also correctly identified simulated dead regions in seven CI users. The revised PECAP algorithm provides an estimate of the electrode-to-neuron interface in CIs that could be used to inform and optimize CI stimulation strategies for individual patients in clinical settings.

scholarly journals Effect of Depth of Total Intravenous General Anesthesia on Intraoperative Electrically Evoked Compound Action Potentials in Cochlear Implantation Surgery

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Ala”a Alhowary ◽  
Abdelwahab Aleshawi ◽  
Obada Alali ◽  
Manal Kassab ◽  
Diab Bani Hani ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Cochlear Implantation ◽  
Action Potentials ◽  
Compound Action Potential ◽  
Cochlear Implant Surgery ◽  
Compound Action Potentials ◽  
Evoked Compound Action Potential ◽  
Electrode Lead ◽  
Intravenous General Anesthesia ◽  
Compound Action

Purpose. This study aims to compare the effect of the depth of total intravenous anesthesia (TIVA) on intraoperative electrically evoked compound action potential (e-ECAP) thresholds in cochlear implant operations. Methods. Prospectively, a total of 39 patients aged between 1 and 48 years who were scheduled to undergo cochlear implantation surgeries were enrolled in this study. Every patient received both light and deep TIVA during the cochlear implant surgery. The e-ECAP thresholds were obtained during the light and deep TIVA. Results. After comparing the e-ECAP means for each electrode (lead) between the light and deep anesthesia, no significant differences were detected between the light and deep anesthesia. Conclusion. The depth of TIVA may have no significant influence on the e-ECAP thresholds as there was no statistical difference between the light and deep anesthesia.

Use of Electrically Evoked Compound Action Potentials for Cochlear Implant Fitting

2018 ◽  
Vol 39 (3) ◽  
pp. 401-411 ◽  
Author(s):  
Johan J. de Vos ◽  
Jan Dirk Biesheuvel ◽  
Jeroen J. Briaire ◽  
Pieter S. Boot ◽  
Margriet J. van Gendt ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Action Potentials ◽  
Compound Action Potentials ◽  
Compound Action
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