US-12623076-B2 - Electrode selection based on impedance for sensing or stimulation

Abstract

An example medical device includes processing circuitry configured to determine an electrode impedance value for each of one or more electrodes of a lead coupled to the medical device, identify one or more of the electrodes having electrode impedance values that are greater than electrode impedance values of other electrodes of the lead, from the identified one or more electrodes, determine a recommendation of electrodes to use for sensing a signal, and output information indicative of the recommendation.

Inventors

• David A. Dinsmoor
• Juan G. Hincapie

Assignees

• MEDTRONIC, INC.

Dates

Publication Date

20260512

Application Date

20220218

Claims (20)

1. 1 . A medical device comprising: processing circuitry configured to: determine an electrode impedance value for each of a plurality of electrodes of a lead coupled to the medical device; identify a subset of one or more electrodes from the plurality of electrodes, the subset of one or more electrodes of the lead having electrode impedance values that are greater than electrode impedance values of other electrodes of the lead that are not in the subset; determine a recommendation of one or more electrodes from the subset of one or more electrodes to use for sensing a signal subsequent to placement of the lead; and output information indicative of the recommendation.
2. 2 . The medical device of claim 1 , wherein the signal is an evoked compound action potential (ECAP) signal of a patient.
3. 3 . The medical device of claim 1 , wherein at least one of the recommended electrodes is configured to be under a laminar bone of a patient.
4. 4 . The medical device of claim 1 , wherein to determine the electrode impedance value, the processing circuitry is configured to determine at least one of: a first bipolar electrode impedance value for the plurality of electrodes of the lead, wherein the first bipolar electrode impedance value is determined based on an impedance between two or more electrodes of the lead, a second bipolar electrode impedance value for the plurality of electrodes of the lead, wherein the second bipolar electrode impedance value is determined based on an impedance between one of the electrodes of the lead and an electrode of another lead, or a unipolar electrode impedance value for the plurality of electrodes of the lead, wherein the unipolar electrode impedance value is determined based on an impedance between the one or more electrodes of the lead and an indifferent electrode that is not on the lead.
5. 5 . The medical device of claim 1 , wherein to identify the subset of one or more electrodes, the processing circuitry is configured to determine pairs of the electrodes that have a greater impedance than other pairs of the electrodes.
6. 6 . The medical device of claim 1 , wherein the processing circuitry is configured to determine which electrodes of the subset of one or more electrodes are near a proximal or distal end of the lead, and wherein to determine the recommendation of one or more electrodes from the subset of one or more electrodes, the processing circuitry is configured to determine the recommendation based on the determination of which electrodes of the subset of one or more electrodes are near the proximal or distal end of the lead.
7. 7 . The medical device of claim 1 , wherein the processing circuitry is configured to determine a recommendation of electrodes to use for stimulation based on the electrode impedance value.
8. 8 . The medical device of claim 1 , wherein the processing circuitry is configured to determine a recommendation of electrodes to use for stimulation based on the electrode impedance value and the signal sensed by the one or more electrodes recommended to use for sensing the signal.
9. 9 . The medical device of claim 1 , wherein at least one electrode of the subset of electrodes is located in a dorsal epidural space of a spine, and a laminar bone is dorsal to the at least one electrode and partially or fully covering the electrode.
10. 10 . A method comprising: determining an electrode impedance value for each of a plurality of electrodes of a lead coupled to a medical device; identifying a subset of one or more electrodes from the plurality of electrodes, the subset of one or more electrodes of the lead having electrode impedance values that are greater than electrode impedance values of other electrodes of the lead that are not in the subset; determining a recommendation of one or more electrodes from the subset of one or more electrodes to use for sensing a signal subsequent to placement of the lead; and outputting information indicative of the recommendation.
11. 11 . The method of claim 10 , wherein the signal is an evoked compound action potential (ECAP) signal of a patient.
12. 12 . The method of claim 10 , wherein at least one of the recommended electrodes is configured to be under a laminar bone of a patient.
13. 13 . The method of claim 10 , wherein identifying the subset of one or more electrodes comprises determining pairs of the electrodes that have a greater impedance than other pairs of the electrodes.
14. 14 . The method of claim 10 , further comprising determining which electrodes of the subset of one or more electrodes are near a proximal or distal end of the lead, and wherein determining the recommendation of one or more electrodes from the subset of one or more electrodes comprises determining the recommendation based on the determination of which electrodes of the subset of one or more electrodes are near the proximal or distal end of the lead.
15. 15 . The method of claim 10 , further comprising determining a recommendation of electrodes to use for stimulation based at least in part on (1) the electrode impedance value or (2) the electrode impedance value and the sensed signal.
16. 16 . The method of claim 10 , wherein determining the electrode impedance comprises determining at least one of: a first bipolar electrode impedance value for the plurality of electrodes, wherein the first bipolar electrode impedance value is determined based on an impedance between electrodes on the lead, a second bipolar electrode impedance value for the plurality of electrodes, wherein the second bipolar electrode impedance value is determined based on an impedance between an electrode on the lead and an electrode on another lead, or a unipolar electrode impedance value for the plurality of electrodes, wherein the unipolar electrode impedance value is determined based on an impedance between the one or more electrodes and an indifferent electrode that is not on the lead.
17. 17 . A method for selecting sensing electrodes, the method comprising: receiving information indicative of an electrode impedance value for a plurality of electrodes of a lead; identifying a subset of one or more electrodes from the plurality of electrodes for sensing a signal based on the electrode impedance value for the plurality of electrodes, wherein the identified subset of one or more electrodes include electrodes having electrode impedance values that are greater than electrode impedance values of other electrodes on the lead that are not in the subset; and selecting one or more electrodes from the subset of one or more electrodes to sense the signal subsequent to placement of the lead.
18. 18 . The method of claim 17 , wherein the signal is an evoked compound action potential (ECAP) signal.
19. 19 . The method of claim 17 , wherein selecting the one or more electrodes from the subset of one or more electrodes comprises selecting the one or more electrodes of the subset of one or more electrodes that are on a proximal or distal end of the lead.
20. 20 . A computer readable storage medium having instructions stored thereon that when executed cause one or more processors to: determine an electrode impedance value for each of a plurality of electrodes of a lead coupled to a medical device; identify a subset of one or more electrodes from the plurality of electrodes, the subset of one or more electrodes of the lead having electrode impedance values that are greater than electrode impedance values of other electrodes of the lead that are not in the subset; determine a recommendation of one or more electrodes from the subset of one or more electrodes to use for sensing a signal subsequent to placement of the lead; and output information indicative of the recommendation.

Description

This application is a U.S. National Stage entry under 35 U.S.C. § 371 of International Application No. PCT/US2022/070735, filed Feb. 18, 2022, which claims priority to U.S. Provisional Patent Application No. 63/152,915, filed Feb. 24, 2021, the entire content of each of which is incorporated herein by reference. TECHNICAL FIELD This disclosure generally relates to medical devices, and more specifically, for electrode selection for sensing or stimulation. BACKGROUND Medical devices may be external or implanted and may be used to deliver electrical stimulation therapy to patients via various tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. A medical device may deliver electrical stimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Stimulation proximate the spinal cord, proximate the sacral nerve, within the brain, and proximate peripheral nerves are often referred to as spinal cord stimulation (SCS), sacral neuromodulation (SNM), deep brain stimulation (DBS), and peripheral nerve stimulation (PNS), respectively. Electrical stimulation may be delivered to a patient by the medical device in a train of electrical pulses, and parameters of the electrical pulses may include a frequency, an amplitude, a pulse width, and a pulse shape. An evoked compound action potential (ECAP) is synchronous firing of a population of neurons which occurs in response to the application of a stimulus including, in some cases, an electrical stimulation by a medical device. SUMMARY In general, systems, devices, and techniques are described for determining electrodes to use for sensing signals and/or outputting stimulation signals. For ease of description and not limitation, the examples are described with respect to sensing evoked compound action potential (ECAP) signals. ECAP signals tend to emanate in all directions from the neural target being sensed in response to an electrical stimulation. This disclosure describes example techniques to determine which electrodes are more likely to reliably sense the ECAP signal. A bone, such as a laminar bone, tends to have higher electrical impedance compared to nearby tissue. Accordingly, the bone tends to restrict the emanation of the ECAP signal and confines the ECAP signal. For instance, a laminar bone tends to constrain the ECAP signal to a region towards the spinal cord. In one or more examples, the electrodes that are under a bone (e.g., ventral to the laminar hone) may be better suited to sense ECAP signals because the bone directs the ECAP signal towards such electrodes. Under the bone refers to the electrodes being fully or partially covered by the hone where the electrode lies on the tissue (e.g., the dura overlaying the spinal cord). Because the bone tends to have higher electrical impedance, electrodes under the bone tend to have higher electrode impedance as compared to electrodes between bones, or under a lower impedance part of the body such as the ligamentum flavum or the epidural fat. Electrode impedance of an electrode may refer to the impedance between two electrodes on a lead (e.g., bipolar impedance between two electrodes on one lead or between two electrodes on different leads) or impedance between an electrode on a lead and an indifferent electrode (e.g., unipolar impedance), where the indifferent electrode is not on the lead. This disclosure describes example techniques to determine impedance of electrodes from which electrodes that are likely to be under the bone can be selected for sensing ECAP signals. In this way, rather than relying only on imaging techniques to determine whether electrodes are under bone, the example techniques provide for utilizing electrical measurements, such as impedance obtained at least in part using one or more implanted electrodes, to determine whether electrodes are under the hone, allowing for a less intrusive way of determining electrode positioning for selecting electrodes that are well positioned for ECAP signal sensing. Furthermore, in some examples, having electrodes positioned under the bone may be beneficial because the bone applies pressure to the lead that causes the electrodes to be in closer proximity to the neural target being sensed. Also, although the above is described for selection of implanted electrodes for sensing of ECAP signals, impedance measurements may also be utilized for sensing other types of signals and/or determining which implanted electrodes to use for delivery of stimulation. In one example, this disclosure describes a medical device comprising processing circuitry configured to determine an electrode impedance value for each of one or more electrodes of a lead coupled to the medical device,