Apparatus and method for determining the relative position and orientation of neurostimulation leads

• US 20060122654A1
• Filed: 01/30/2006
• Published: 06/08/2006
• Est. Priority Date: 12/04/2001
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Thacker, James R., Bradley, Kerry
• Granted Patent: US 8,682,447 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes

Abstract

Interelectrode impedance or electric field potential measurements are used to determine the relative orientation of one lead to other leads in the spinal column or other body/tissue location. Interelectrode impedance is determined by measuring impedance vectors. The value of the impedance vector is due primarily to the electrode-electrolyte interface, and the bulk impedance between the electrodes. The bulk impedance between the electrodes is, in turn, made up of (1) the impedance of the tissue adjacent to the electrodes, and (2) the impedance of the tissue between the electrodes. In one embodiment, the present invention makes both monopolar and bipolar impedance measurements, and then corrects the bipolar impedance measurements using the monopolar measurements to eliminate the effect of the impedance of the tissue adjacent the electrodes. The orientation and position of the leads may be inferred from the relative minima of the corrected bipolar impedance values. These corrected impedance values may also be mapped and stored to facilitate a comparison with subsequent corrected impedance measurement values. Such comparison allows a determination to be made as to whether the lead position and/or orientation has changed appreciably over time. In another embodiment, one or more electrodes are stimulated and the resulting electric field potential on the non-stimulated electrodes is measured. Such field potential measurements provide an indication of the relative orientation of the electrodes. Once known, the relative orientation may be used to track lead migration, to setup stimulation configurations and parameters for nominal stimulation and/or navigation. Also, such measurements allow automatic adjustment of stimulation energy to a previously-defined optimal potential field in the case of lead migration or postural changes.

Claims

1. A method, comprising:

determining the relative position of first and second multiple-electrode leads; and

displaying the relative position of the first and second multiple-electrode leads.

2. A method as claimed in claim 1, wherein determining the relative position of first and second multiple-electrode leads comprises measuring impedance vectors between lead electrodes and inferring the relative position of the leads by the relative minima of the impedance vectors.

3. A method as claimed in claim 1, wherein determining the relative position of the first and second multiple-electrode leads comprises measuring impedance vectors between respective electrode pairs that each include one of the electrodes on the first multiple-electrode lead and one of the electrodes on the second multiple-electrode lead.

4. A method as claimed in claim 1, wherein determining the relative position of first and second multiple-electrode leads comprises applying a stimulus to a selected group of lead electrodes and measuring the voltage at the electrodes not included in the group of electrodes to which the stimulus is applied.

5. A method as claimed in claim 1, wherein displaying the relative position of the first and second multiple-electrode leads comprises displaying the relative position of the first and second multiple-electrode leads on a programmer display.

6. A method as claimed in claim 1, further comprising:

comparing the displayed relative position of the first and second multiple-electrode leads with a display of a previously measured relative position of the first and second multiple-electrode leads.

7. A method as claimed in claim 1, further comprising:

comparing the displayed relative position of the first and second multiple-electrode leads with a display of a previously entered relative position of the first and second multiple-electrode leads.

8. An apparatus for use with first and second leads that include respective pluralities of electrodes, the apparatus comprising:

means for determining the relative position of the first and second leads; and

means for displaying the relative position of the first and second leads.

9. An apparatus as claimed in claim 8, further comprising:

means for comparing the displayed relative position of the first and second leads with a display of a previously measured relative position of the first and second leads.

10. An apparatus as claimed in claim 8, further comprising:

means for comparing the displayed relative position of the first and second leads with a display of a previously entered relative position of the first and second leads.

11. An apparatus for use with first and second leads that include respective pluralities of electrodes, the apparatus comprising:

a display;

circuitry to determine the relative position of the first and second leads; and

circuitry to display the relative position of the first and second leads on the display.

12. An apparatus as claimed in claim 11, wherein the display is associated with a programmer.

13. An apparatus as claimed in claim 11, wherein the circuitry to determine the relative position comprises circuitry to measure impedance vectors between lead electrodes and infer the relative position of the leads by the relative minima of the impedance vectors.

14. An apparatus as claimed in claim 11, wherein the circuitry to determine the relative position comprises circuitry to measure impedance vectors between respective electrode pairs that each include one of the electrodes on the first lead and one of the electrodes on the second lead.

15. An apparatus as claimed in claim 11, wherein the circuitry to determine the relative position comprises circuitry to apply a stimulus to a selected group of lead electrodes and measure the voltage at the electrodes not included in the group of electrodes to which the stimulus is applied.

16. An apparatus as claimed in claim 11, further comprising:

circuitry to compare the displayed relative position of the first and second leads with a display of a previously measured relative position of the first and second leads.

17. An apparatus as claimed in claim 11, further comprising:

circuitry to compare the displayed relative position of the first and second leads with a display of a previously entered relative position of the first and second leads.