Activity sensing for stimulator control

• US 8,831,737 B2
• Filed: 05/31/2013
• Issued: 09/09/2014
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Wesselink, Wilbert A.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): MORALES, JON ERIC C
• Application Number:
  US13/907,163
• Publication Number:
  US 20130268022A1
• Time in Patent Office: 466 Days
• Field of Search: 607/2, 607/62, 607/117
• US Class Current: 607/62
• CPC Class Codes: A61B 5/107 Measuring physical dimensions, e.g. size of the entire body or parts thereof
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/6886 Monitoring or controlling distance between sensor and tissue
• CPC Class Codes: A61N 1/0531 Brain cortex electrodes
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/0553 Paddle shaped electrodes, e.g. for laminotomy
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: A61N 1/36135 using physiological parameters
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration

Abstract

The disclosure describes a system that measures the distance between one or more electrodes and tissue of a patient, and controls one or more parameters of the stimulation delivered to the tissue by the electrodes based on the measured distance. The system controls the measurement of the distance between the electrodes and the tissue as a function of activity of the patient. The system uses, for example, a piezoelectric transducer to sense activity of the patient, and may determine whether or how frequently to measure the distance between electrodes and tissue based on the sensed physical activity. A piezoelectric transducer may be used both to sense activity and to measure the distance between the electrodes and the tissue.

Claims

1. A system comprising:

a sensor configured to measure a distance between an electrode and a tissue of a patient to which the electrode delivers stimulation; and

at least one processor configured to;

control the sensor to measure the distance between the electrode and the tissue of the patient;

determine whether the measured distance has changed; and

responsive to determining that the measured distance has changed, adjust, as a function of the measured distance, a parameter of the stimulation to provide a substantially consistent stimulation intensity at the tissue, wherein adjusting the parameter of the stimulation comprises adjusting a parameter of one or more electrical pulses that are generated by a stimulation generator and that are delivered by the electrode to the tissue of the patient.

2. The system of claim 1,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is configured to determine how frequently to control the first sensor to measure the distance between the electrode and the tissue of the patient as a function of the sensed activity.

3. The system of claim 2, further comprising a lead that carries the electrode and the first and second sensors.

4. The system of claim 2, wherein the second sensor comprises a piezoelectric transducer.

5. The system of claim 2, wherein the first sensor ultrasonically measures the distance.

6. The system of claim 5, wherein the first sensor comprises a piezoelectric transducer.

7. The system of claim 2, wherein the first and second sensors comprise a common piezoelectric transducer.

8. The system of claim 1,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is configured to compare the sensed activity to a threshold value, and to control the first sensor to measure the distance when the sensed activity exceeds the threshold value.

9. The system of claim 1,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is configured to compare the sensed activity to a plurality of thresholds, each of the thresholds associated with a respective one of a plurality of distance measurement frequencies, and to control the first sensor to measure the distance at one of the plurality of frequencies based on the comparison.

10. The system of claim 1, further comprising an implantable medical device that includes the stimulation generator, wherein the implantable medical device is configured to deliver the stimulation via the electrode, and wherein the at least one processor comprises one or more processors of the implantable medical device.

11. The system of claim 1, wherein the tissue comprises tissue of the spinal cord.

12. The system of claim 1, wherein the tissue comprises brain tissue, cardiac tissue, gastric tissue, muscular tissue, or nerve tissue.

13. The system of claim 1, wherein the electrode is implanted within the patient.

14. The system of claim 1, wherein the at least one processor is configured to control the sensor to measure the distance upon receiving an indication of activity of the patient.

15. The system of claim 1, wherein adjusting the parameter of the one or more electrical pulses that are generated by the stimulation generator comprises adjusting at least one of a pulse amplitude, a pulse width, and a pulse rate of the one or more electrical pulses.

16. A system comprising:

a sensor configured to measure a distance between an electrode and a tissue of a patient to which the electrode delivers stimulation; and

at least one processor configured to;

control the sensor to measure the distance upon determining a likelihood that the distance between the electrode and the tissue has changed;

determine whether the measured distance has changed; and

responsive to determining that the measured distance has changed, adjust, as a function of the measured distance, a parameter of the stimulation delivered by the electrode, wherein adjusting the parameter of the stimulation comprises adjusting a parameter of one or more electrical pulses that are generated by a stimulation generator and that are delivered by the electrode to the tissue of the patient.

17. The system of claim 16,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is further configured to determine how frequently to control the first sensor to measure the distance between the electrode and the tissue of the patient as a function of the sensed activity.

18. The system of claim 17, further comprising a lead that carries the electrode and the first and second sensors.

19. The system of claim 17, wherein the second sensor comprises a piezoelectric transducer.

20. The system of claim 17, wherein the first sensor ultrasonically measures the distance.

21. The system of claim 20, wherein the first sensor comprises a piezoelectric transducer.

22. The system of claim 17, wherein the first and second sensors comprise a common piezoelectric transducer.

23. The system of claim 16,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is configured to compare the sensed activity to a threshold value, and to control the first sensor to measure the distance when the sensed activity exceeds the threshold value.

24. The system of claim 16,

wherein the sensor comprises a first sensor,

wherein the system further comprises a second sensor configured to sense activity of the patient, and

wherein the at least one processor is configured to compare the sensed activity to a plurality of thresholds, each of the thresholds associated with a respective one of a plurality of distance measurement frequencies, and to control the first sensor to measure the distance at one of the plurality of frequencies based on the comparison.

25. The system of claim 16, further comprising an implantable medical device that includes the stimulation generator, wherein the implantable medical device is configured to deliver the stimulation via the electrode, wherein the at least one processor comprises one or more processors of the implantable medical device.

26. The system of claim 16, wherein the tissue comprises tissue of the spinal cord.

27. The system of claim 16, wherein the tissue comprises brain tissue, cardiac tissue, gastric tissue, muscular tissue, or nerve tissue.

28. The system of claim 16, wherein the electrode is implanted within the patient.

29. The system of claim 16, wherein the at least one processor is configured to control the sensor to measure the distance upon receiving an indication of activity of the patient.

30. The system of claim 16, wherein adjusting the parameter of the one or more electrical pulses that are generated by the stimulation generator comprises adjusting at least one of a pulse amplitude, a pulse width, and a pulse rate of the one or more electrical pulses.

31. A method comprising:

controlling, by at least one processor, measurement of a distance between an electrode and a tissue of a patient to which the electrode delivers stimulation;

determining, by the at least one processor, whether the measured distance between the electrode and the tissue of the patient has changed; and

responsive to determining that the measured distance has changed, adjusting, by the at least one processor and as a function of the measured distance, a parameter of the stimulation to provide a substantially consistent stimulation intensity at the tissue, wherein adjusting the parameter of the stimulation comprises adjusting a parameter of one or more electrical pulses that are generated by a stimulation generator and that are delivered by the electrode to the tissue of the patient.

32. A method comprising:

controlling, by at least one processor, measurement of a distance between an electrode and a tissue of a patient to which the electrode delivers stimulation upon determining a likelihood that the distance has changed;

determining, by the at least one processor, whether the measured distance between the electrode and the tissue of the patient has changed; and

responsive to determining that the measured distance has changed, adjusting, by the at least one processor and as a function of the measured distance, a parameter of the stimulation delivered by the electrode, wherein adjusting the parameter of the stimulation comprises adjusting a parameter of one or more electrical pulses that are generated by a stimulation generator and that are delivered by the electrode to the tissue of the patient.