Impedance matching and electrode conditioning in patient interface systems

• US 10,434,308 B2
• Filed: 05/29/2015
• Issued: 10/08/2019
• Est. Priority Date: 05/29/2015
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Isaacson, Benjamin P., Denison, Timothy J., Paralikar, Kunal J., Stanslaski, Scott R.
• Primary Examiner(s): Natnithithadha, Navin
• Assistant Examiner(s): Shostak, Andrey
• Application Number:
  US14/726,028
• Publication Number:
  US 20160346534A1
• Time in Patent Office: 1,593 Days
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/6868 Brain
• CPC Class Codes: A61N 1/0529 Electrodes for brain stimulation
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/36067 Movement disorders, e.g. tremor or Parkinson disease stimulating motor muscle A61N1/36003
• CPC Class Codes: A61N 1/3614 based on impedance measurement
• CPC Class Codes: A61N 1/36185 Selection of the electrode configuration

Abstract

Systems and method may be used for interfacing with a patient. Systems may include a plurality of electrodes in electrical communication with a processor. The processor may determine a relative impedance difference between a first electrode and a second electrode, and apply a sub-therapeutic stimulation pulse to one of the first and second electrodes to adjust the relative impedance difference therebetween. Systems may include a processor capable of one or both of providing therapeutic stimulation to a patient via at least one electrode, and receiving electrical signals indicative of the patient'"'"'s physiological activity. In some examples, the processor may simultaneously provide therapeutic stimulation to a patient and receive electrical signals from the patient indicative of the patient'"'"'s physiological activity.

Claims

1. A system comprising:

a first electrode and a second electrode, the first electrode and the second electrode configured to electrically and chronically engage neural tissue of a patient, wherein neural tissue is brain tissue or spinal cord tissue; and

a processor in communication with the first electrode and the second electrode, the processor configured to;

receive electrical signals representative of a patients physiological activity;

determine a first relative impedance difference between the first electrode and the second electrode, wherein an impedance of the first electrode is greater than an impedance of the second electrode;

cause the impedance of the first electrode to decrease by controlling a stimulation generator to provide a first impedance-reducing stimulation pulse from the first electrode based on the determined relative impedance difference, such that the first relative impedance difference between the first electrode and the second electrode is reduced, wherein the impedance-reducing pulse comprises pulse characteristics configured to reduce a localized electrode-to-neural tissue impedance, wherein an extent of the localized electrode-to-neural tissue impedance reduction effect is less than a distance between the first electrode and a nearest adjacent electrode;

determine a second relative impedance difference between the first electrode and the second electrode;

in response to the second relative impedance difference exceeding a predetermined threshold, cause the impedance of the first electrode to decrease by controlling the stimulation generator to provide a second impedance-reducing stimulation pulse from the first electrode based on the determined relative impedance difference, such that the second relative impedance difference between the first electrode and the second electrode is reduced;

determine a third relative impedance difference between the first electrode and the second electrode; and

in response to the third relative impedance difference satisfying the predetermined threshold, receive subsequent electrical signals with the first electrode and the second electrode having the reduced relative impedance difference.

2. The system of claim 1, further comprising a third electrode in communication with the processor, the third electrode being separate from first electrode and the second electrode and being configured to electrically engage the neural tissue of the patient.

3. The system of claim 2, wherein the processor is further configured to control the stimulation generator to provide a therapeutic treatment stimulation pulse from the third electrode while the processor is simultaneously configured to detect signals from the patient via the first electrode and the second electrode.

4. The system of claim 3, wherein the first electrode, the second electrode, and the third electrode are selectable from a plurality of electrodes.

5. The system of claim 2, wherein the processor is configured to:

control the stimulation generator to provide a test stimulation pulse from the third electrode;

receive signals from the first electrode and the second electrode indicative of the patient'"'"'s physiological activity; and

determine the common-mode rejection ratio (CMRR) between the first electrode and the second electrode based on the received signals.

6. The system of claim 5, wherein the determined CMRR is indicative of the relative impedance difference between the first electrode and the second electrode.

7. The system of claim 5, wherein the processor is configured to, in the event that the determined CMRR is above a predetermined threshold, control the stimulation generator to provide the impedance-reducing stimulation pulse.

8. The system of claim 4, wherein the processor and the plurality of electrodes are implantable within the patient.

9. The system of claim 8, further comprising a user interface by which a user can manually query the system to determine the relative impedance difference between the first electrode and the second electrode and manually instruct the system to provide the first impedance-reducing stimulation pulse from the first electrode.

10. The system of claim 1, wherein the processor is configured to periodically determine the relative impedance difference between the first electrode and the second electrode, and, in the event that the relative impedance difference exceeds a predetermined threshold, provide the first impedance-reducing stimulation pulse from the first electrode.

11. The system of claim 1, wherein the processor is configured to monitor the relative impedance difference between the first electrode and the second electrode while controlling the stimulation generator to provide the first impedance-reducing stimulation pulse and the second impedance-reducing stimulation pulse from the first electrode.

12. The system of claim 11, wherein to monitor the relative impedance difference between the first electrode and the second electrode while controlling the stimulation generator to provide the first impedance-reducing stimulation pulse and the second impedance-reducing stimulation pulse from the first electrode comprises:

periodically ceasing controlling the stimulation generator to provide the first impedance-reducing stimulation pulse or the second impedance-reducing stimulation pulse,

determining the relative impedance difference, and,

in response to the relative impedance difference being above a predetermined threshold, resuming the controlling the stimulation generator to provide the first impedance-reducing stimulation pulse or the second impedance-reducing stimulation pulse.

13. The system of claim 1, wherein the processor is configured to determine the relative impedance difference between the first electrode and the second electrode based on a result of signals received from the first electrode and the second electrode.

14. The system of claim 1, wherein the processor is configured to control the stimulation generator to provide a plurality of stimulation pulses to at least one of the first electrode and the second electrode.

15. The system of claim 1, wherein the first impedance-reducing stimulation pulse and the second impedance-reducing stimulation pulse has at least one non-therapeutic characteristic.

16. The system of claim 1 wherein the received electrical signals are generated from local field potentials (LFP) within the neural tissue.