ECAP spread of excitation with virtual channels and physical electrodes.
The primary goal of this study was to evaluate physiological spatial excitation patterns for stimulation of adjacent physical electrodes and intermediate virtual channels. Two experiments were conducted that utilized electrically evoked compound action potential (ECAP) spread-of-excitation (SOE) functions obtained with the traditional forward-masking subtraction method. These two experiments examined spatial excitation patterns for virtual-channel maskers and probes, respectively. In Experiment 1, ECAP SOE patterns were obtained for maskers applied to physical electrodes and virtual channels to determine whether virtual-channel maskers yield SOE patterns similar to those predicted from physical electrodes. In Experiment 2, spatial separation of SOE functions was compared for two adjacent physical probe electrodes and the intermediate virtual channel to determine the extent to which ECAP SOE patterns for virtual-channel probes are spatially separate from those obtained with physical electrodes. Data were obtained for three electrode regions (basal, middle, apical) for 35 ears implanted with Cochlear (N = 16) or Advanced Bionics (N = 19) devices. Results from Experiment 1 showed no significant difference between predicted and measured ECAP amplitudes for Advanced Bionics subjects. Measured ECAP amplitudes for virtual-channel maskers were significantly larger than the predicted amplitudes for Cochlear subjects; however, the difference was <2 μV and thus is likely not clinically significant. Results from Experiment 2 showed that the probe set in the apical region demonstrated the least amount of spatial separation amongst SOE functions, which may be attributed to more uniform nerve survival patterns, closer electrode spacing, and/or the tapered geometry of the cochlea. As expected, adjacent physical probes demonstrated greater spatial separation than for comparisons between each physical probe and the intermediate virtual channel. Finally, the virtual-channel SOE functions were generally weighted toward the basal electrode in the pair.
['Hughes|Michelle L|ML|', 'Stille|Lisa J|LJ|', 'Baudhuin|Jacquelyn L|JL|', 'Goehring|Jenny L|JL|']
D000200:Action Potentials D000293:Adolescent D000328:Adult D000368:Aged D000369:Aged, 80 and over D001701:Bionics D002648:Child D002675:Child, Preschool D019929:Cochlear Implantation D003054:Cochlear Implants D017097:Electric Impedance D004558:Electric Stimulation D004566:Electrodes D004867:Equipment Design D006801:Humans D007223:Infant D008875:Middle Aged D009474:Neurons D012815:Signal Processing, Computer-Assisted D013686:Telemetry D055815:Young Adult
ECAP spread of excitation electrically evoked compound action potential SOE virtual-channel maskers Advanced Bionics AB BEDCS Bionic Ear Data Collection System CI CL CPI II Clinical Programming Interface MPI NRT Neural Response Telemetry PM PSP Platinum Series Processor RM ANOVA SD VM cochlear implant current level units masker-probe interval physical-electrode maskers pps pulses per second repeated-measures analysis of variance standard deviation