Method and system for generating a cochlear implant program using multi-electrode stimulation to elicit the electrically-evoked compound action potential
First Claim
1. In a cochlear implant system having multiple electrode contacts through which electrical stimuli are adapted to be applied to a patient'"'"'s inner ear, a method of generating stimulation parameters for use by the cochlear implant system, comprising:
- generating electrical stimuli with selectable degrees of amplitude intensity;
delivering the electrical stimuli to selected groups of electrode contacts while gradually adjusting the intensity of the electrical stimuli and while monitoring at least one electrode contact near the group of electrode contacts receiving the delivered electrical stimuli for the occurrence of an evoked compound action potential (ECAP);
determining an electrical-stimuli intensity threshold level (tNRI) associated with the occurrence of the ECAP for each selected group of electrode contacts, the tNRI threshold level for all of the selected groups comprising tNRI threshold data;
processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact; and
using the contour of tNRI threshold levels to define stimulation parameters thereafter used by the cochlear implant system to control the intensity of the electrical stimuli applied through the electrode contacts,wherein processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact comprises combining the tNRI threshold level data from each selected group of electrodes and smoothing discontinuities therein; and
wherein smoothing discontinuities in the tNRI threshold data comprises applying a three-point weighted average, with the first and last data points of a three-consecutive data points being weighted a first prescribed percentage, and with the middle data point being weighted a second prescribed percentage, where the second prescribed percentage is greater than the first prescribed percentage.
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Abstract
A multichannel cochlear implant system spatially spreads the excitation pattern in the target neural tissue by either: (1) rapid sequential stimulation of a small group of electrodes, or (2) simultaneously stimulating a small group of electrodes. Such multi-electrode stimulation stimulates a greater number of neurons in a synchronous manner, thereby increasing the amplitude of the extra-cellular voltage fluctuation and facilitating its recording. The electrical stimuli are applied simultaneously (or sequentially at a rapid rate) on selected small groups of electrodes while monitoring the evoked compound action potential (ECAP) on a nearby electrode. The presence of an observable ECAP not only validates operation of the implant device at a time when the patient may be unconscious or otherwise unable to provide subjective feedback, but also provides a way for the magnitude of the observed ECAP to be recorded as a function of the amplitude of the applied stimulus. From this data, a safe, efficacious and comfortable threshold level can be obtained which may be used thereafter as the initial setting of the stimulation parameters of the neurostimulation device, or to guide the setting of the stimulation parameters of the neurostimulation device.
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Citations
32 Claims
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1. In a cochlear implant system having multiple electrode contacts through which electrical stimuli are adapted to be applied to a patient'"'"'s inner ear, a method of generating stimulation parameters for use by the cochlear implant system, comprising:
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generating electrical stimuli with selectable degrees of amplitude intensity; delivering the electrical stimuli to selected groups of electrode contacts while gradually adjusting the intensity of the electrical stimuli and while monitoring at least one electrode contact near the group of electrode contacts receiving the delivered electrical stimuli for the occurrence of an evoked compound action potential (ECAP); determining an electrical-stimuli intensity threshold level (tNRI) associated with the occurrence of the ECAP for each selected group of electrode contacts, the tNRI threshold level for all of the selected groups comprising tNRI threshold data; processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact; and using the contour of tNRI threshold levels to define stimulation parameters thereafter used by the cochlear implant system to control the intensity of the electrical stimuli applied through the electrode contacts, wherein processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact comprises combining the tNRI threshold level data from each selected group of electrodes and smoothing discontinuities therein; and wherein smoothing discontinuities in the tNRI threshold data comprises applying a three-point weighted average, with the first and last data points of a three-consecutive data points being weighted a first prescribed percentage, and with the middle data point being weighted a second prescribed percentage, where the second prescribed percentage is greater than the first prescribed percentage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for setting stimulation parameters used in a cochlear implant system, the cochlear implant system having a multiplicity of electrode contacts and means for delivering electrical stimuli to a selected electrode contact or a selected group of electrode contacts, the method comprising steps for:
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(a) defining a first group of electrode contacts; (b) defining an initial stimulation level; (c) simultaneously applying electrical stimuli at the defined stimulation level to the defined group of electrode contacts; (d) determining whether an evoked compound action potential (ECAP) is observed on an electrode contact near the defined group of electrode contacts, and if not, adjusting the defined stimulation level and repeating step (c); (e) recording the magnitude of the ECAP and the corresponding stimulation level by measuring the peak-to-peak amplitude of the ECAP from ECAP peak N1 to ECAP peak P2; (f) determining whether at least three ECAP measurements have been made for the selected croup of electrode contacts, each measurement being made at a different stimulation level, and if not, adjusting the defined stimulation level and repeating steps (c) through (e); (g) determining an appropriate NRI threshold (tNRI) for the defined electrode group of electrode contacts; (h) determining whether all desired groups of electrode contacts have been evaluated to determine a tNRI threshold, and if not, defining a next group of electrode contacts and repeating steps (b) through (g); (I) processing the tNRI threshold for each group of electrode contacts to obtain tNRI thresholds for each individual electrode contact; and (j) using the processed tNRI thresholds as a guide for setting stimulation parameters of the cochlear implant system. - View Dependent Claims (9, 10)
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11. A cochlear implant system comprising:
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multiple electrode contacts through which electrical stimuli are adapted to be applied to a patient'"'"'s inner ear; means for generating electrical stimuli with selectable degrees of amplitude intensity; means for delivering the electrical stimuli to selected groups of electrode contacts while gradually adjusting the intensity of the electrical stimuli and while monitoring at least one electrode contact near the group of electrode contacts receiving the delivered electrical stimuli for the occurrence of an evoked compound action potential (ECAP); means for determining an electrical-stimuli intensity threshold level (tNRI) associated with the occurrence of the ECAP for each selected group of electrode contacts, the tNRI threshold level for all of the selected groups comprising tNRI threshold data; means for processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact; and means for using the contour of tNRI threshold levels to define stimulation parameters thereafter used by the cochlear implant system to control the intensity of the electrical stimuli applied through the electrode contacts, wherein the means for processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact comprises means for combining the tNRI threshold level data from each selected croup of electrodes and means for smoothing discontinuities therein; and wherein the means for smoothing discontinuities in the tNRI threshold data comprises means for applying a three-point weighted average, with the first and last data points of a three-consecutive data points being weighted a first prescribed percentage, and with the middle data point being weighted a second prescribed percentage, where the second prescribed percentage is greater than the first prescribed percentage. - View Dependent Claims (12, 13, 14)
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15. In a cochlear implant system having multiple electrode contacts through which electrical stimuli are adapted to be applied to a patient'"'"'s inner ear, a method of generating stimulation parameters for use by the cochlear implant system, comprising:
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generating electrical stimuli with selectable degrees of amplitude intensity; delivering the electrical stimuli to selected groups of electrode contacts, such that at least two of the selected groups of electrode contacts output an electrical current into the inner ear tissue, while gradually adjusting the intensity of the electrical stimuli and while monitoring for the occurrence of an evoked compound action potential (ECAP) with another separate electrode contact near the at least two of the selected group electrode contacts; determining an electrical-stimuli intensity threshold level (tNRI) associated with the occurrence of the ECAP for each selected group of electrode contacts, the tNRI threshold level for all of the selected groups comprising tNRI threshold data; processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact; and using the contour of tNRI threshold levels to define stimulation parameters thereafter used by the cochlear implant system to control the intensity of the electrical stimuli applied through the electrode contacts. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for setting stimulation parameters used in a cochlear implant system, the cochlear implant system having a multiplicity of electrode contacts and means for delivering electrical stimuli to a patient'"'"'s inner ear with a selected electrode contact or a selected group of electrode contacts, the method comprising steps for:
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(a) defining a first group of electrode contacts; (b) defining an initial stimulation level; (c) simultaneously applying electrical stimuli at the defined stimulation level to the defined group of electrode contacts, wherein at least two of the defined groups of electrode contacts output an electrical current into the inner ear tissue, while gradually adjusting the intensity of the electrical stimuli; (d) determining whether an evoked compound action potential (ECAP) is observed with another electrode contact near the at least two of the defined group of electrode contacts, and if not, adjusting the defined stimulation level and repeating step (c); (e) recording the magnitude of the ECAP and the corresponding stimulation level; (f) determining whether sufficient ECAP data has been obtained, and if not, adjusting the defined stimulation level and repeating steps (c) through (e); (g) determining an appropriate NRI threshold (tNRI) for the defined electrode group of electrode contacts; (h) determining whether all desired groups of electrode contacts have been evaluated to determine a tNRI threshold, and if not, defining a next group of electrode contacts and repeating steps (b) through (g); (I) processing the tNRI threshold for each group of electrode contacts to obtain tNRI thresholds for each individual electrode contact; and (j) using the processed tNRI thresholds as a guide for setting stimulation parameters of the cochlear implant system. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A cochlear implant system comprising:
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multiple electrode contacts through which electrical stimuli are adapted to be applied to a patient'"'"'s inner ear; means for generating electrical stimuli with selectable degrees of amplitude intensity; means for delivering the electrical stimuli to selected groups of electrode contacts, such that at least two of the selected groups of electrode contacts output an electrical current into the inner ear tissue, while gradually adjusting the intensity of the electrical stimuli and while monitoring for the occurrence of an evoked compound action potential (ECAP) with another separate electrode contact near the at least two of the selected groups of electrode contacts receiving the delivered electrical stimuli for the occurrence of an evoked compound action potential (ECAP); means for determining an electrical-stimuli intensity threshold level (tNRI) associated with the occurrence of the ECAP for each selected group of electrode contacts, the tNRI threshold level for all of the selected groups comprising tNRI threshold data; means for processing the tNRI threshold data to determine a contour of tNRI threshold levels that defines a tNRI threshold for each electrode contact; and means for using the contour of tNRI threshold levels to define stimulation parameters thereafter used by the cochlear implant system to control the intensity of the electrical stimuli applied through the electrode contacts. - View Dependent Claims (28, 29, 30, 31, 32)
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Specification