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1. WO2005070494 - METHOD OF ROUTING ELECTRICAL CURRENT TO BODILY TISSUES VIA IMPLANTED PASSIVE CONDUCTORS

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WHAT IS CLAIMED IS :

1. An implant for electrically stimulating a target body tissue in a subject, the implant, once implanted, providing a conductive pathway for at least a portion of the electrical current flowing between surface cathodic and anodic electrodes positioned in spaced relationship on the subject' s skin and transmitting that portion of the electrical current to the target body tissue, the implant comprising:

an electrical conductor of sufficient length to extend, once implanted, from
subcutaneous tissue located below the surface cathodic electrode to the target body tissue, the electrical conductor having a pick-up end and a stimulating end and being insulated between its ends, the pick-up end forming an electrical termination having a sufficient surface area to allow a sufficient portion of the electrical current to flow through the conductor, in preference to flowing through body tissue between the surface cathodic and anodic electrodes, such that the target body tissue is stimulated, and the stimulating end forming an electrical termination for delivering the portion of electrical current to the target body tissue.

2. The implant according to claim 1, wherein the implant further comprises:
an electrical return conductor of sufficient length to extend, once implanted, from the target tissue to subcutaneous tissue located below the surface anodic electrode, the return conductor having a collecting end and a returning end and being insulated between its ends, the collecting end forming an electrical termination having a sufficient surface area to allow a portion of the current delivered to the target body tissue to return through the return conductor in preference to returning through body tissue, and the returning end forming an electrical termination that returns the electrical current to the surface anodic electrode via the subcutaneous tissue and skin underlying that electrode.

3. The implant according to claim 1 or 2, wherein one or both of the conductor and return conductor is formed from a metal wire, carbon fibers, a conductive rubber or other conductive polymer, or a conductive salt solution in rubber.

4. The implant according to claim 3, wherein the terminations on one or both ends of the conductor and return conductor provide an enlarged surface in the form of a coil, a spiral, a cuff, a rod, or a plate or sheet in the form of an oval or polygon.

5. The implant according to claim 4, wherein one or more of the terminations are formed from uninsulated ends of the conductor or return conductor, or from other conductive or capacitive materials.

6. The implant according to claim 5, further comprising a conductive or capacitive coating, or oxide layer on one or more of the terminations.

7. The implant according to claim 5, further comprising a coating on one or both of the terminations for providing an anti-inflammatory, an anti-bacterial or a tissue ingrowth effect, the coating being a substance selected from the group consisting of an anti-inflammatory agent, an antibacterial agent, an antibiotic, and a tissue ingrowth promoter.

8. A system for electrically stimulating a target body tissue in a subject comprising:

i) surface cathodic and anodic electrodes for making electrical contact with the subject's skin, and which, when positioned in spaced relationship on the subject's skin, for transmitting electrical current to the target body tissue;

ii) a stimulator external to the subject's body, electrically connected to the surface cathodic and anodic electrodes, the stimulator supplying direct, pulsatile, or alternating current to the surface cathodic and anodic electrodes; and

iii) an implant for picking up a portion of the electrical current flowing between the surface cathodic and anodic electrodes and transmitting that portion of the electrical current to the target body tissue, the implant comprising an electrical conductor of sufficient length to extend, once implanted, from subcutaneous tissue located below the surface cathodic electrode to the target body tissue, the electrical conductor having a pick-up end and a stimulating end and being insulated between its ends, the pick-up end forming an electrical termination having a sufficient surface area to allow a sufficient portion of the electrical current being applied to flow through the conductor, in preference to current flowing through body tissue between the surface cathodic and anodic electrodes, such that the target body tissue is stimulated, and the stimulating end forming an electrical termination for delivering the portion of electrical current to the target body tissue.

9. The system according to claim 8, further comprising an electrical return conductor of sufficient length to extend, once implanted, from the target tissue to subcutaneous tissue located below the surface anodic electrode, the return conductor having a collecting end and a returning end and being insulated between its ends, the collecting end forming an electrical termination having a sufficient surface area to allow a portion of the current delivered to the target body tissue to return through the return conductor in preference to returning through body tissue, and the returning end forming an electrical termination that returns the electrical current to the surface anodic electrode via the subcutaneous tissue and skin underlying that electrode.

10. The system according to claim 8, comprising comprising implanting a plurality of implants as defined in claim 8 for electrically stimulating more than one target body tissue independently or in unison, each implant being implanted entirely under the subject's skin and being of a sufficient length to extend to a different target body tissue, and positioning a plurality of surface cathodic and one or more surface anodic electrodes appropriately relative to the implants to stimulate the different target body tissues independently or in unison.

11. The system according to claim 8, 9 or 10, wherein the conductor is formed from a metal wire, carbon fibers, a conductive rubber or other conductive polymer, or a conductive salt solution in rubber.

12. The system according to claim 11 , wherein the terminations on one or both of the pick-up end or stimulating end provide an enlarged surface in the form of a coil, a spiral, a cuff, a rod, or a plat or sheet in the form of an oval or polygon.

13. The system according to claim 12, wherein the surface cathodic and anodic electrodes comprise a conductive plate or sheet, a conductive gel electrode, a conductive rubber or polymer electrode that may be partially coated with an electrode paste or gel, or a moistened absorbent pad electrode.

14. The system according to claim 12, wherein the terminations can be formed from uninsulated ends of the conductor itself, or from other conductive or capacitive materials.

15. The system according to claim 12, further comprising a conductive or capacitive coating, or oxide layer on one or both of the terminations.

16. The system according to claim 12, further comprising a coating on one or both of the terminations for providing an anti-inflammatory, an anti-bacterial or a tissue ingrowth effect, the coating being a substance selected from the group consisting of an anti-inflammatory agent, an antibacterial agent, an antibiotic, and a tissue ingrowth promoter.

17. A method for electrically stimulating a target body tissue in a subject comprising the steps of:
a) providing an implant to act as a conductive pathway for at least a portion of the electrical current flowing between surface cathodic and anodic electrodes positioned in spaced relationship on the subject's skin and transmitting the portion of the electrical current to the target body tissue, the implant comprising an electrical conductor of sufficient length to extend, once implanted, from subcutaneous tissue located below the surface cathodic electrode to the target body tissue, the electrical conductor having a pick-up end and a stimulating end and being insulated between its ends, the pick-up end forming an electrical termination having a sufficient surface area to allow a sufficient portion of the electrical current to flow through the conductor, in preference to flowing through body tissue between the surface cathodic and anodic electrodes, such that the target body tissue is stimulated, and the stimulating end forming an electrical termination for delivering the portion of electrical current to the target body tissue;

b) implanting the implant entirely under the subject's skin, with the pick-up end positioned in subcutaneous tissue located below the surface cathodic electrode, and the stimulating end positioned proximate to the target body tissue;

c) positioning the surface cathodic and anodic electrodes in spaced relationship on the subject's skin, with the surface cathodic electrode positioned over the pick-up end of the electrical conductor so the portion of the current is transmitted through the conductor to the target body tissue, and so that the current flows through the target body tissue and returns to the anodic surface electrode through body tissues or through an implanted electrical return conductor extending between the target body tissue and subcutaneous tissue located below the surface anodic electrode; and

d) applying direct, pulsatile or alternating electrical current between the surface cathodic electrode and the surface anodic electrode to cause the portion of the electrical current to flow through the implant sufficient to stimulate the target body tissue.

18. The method according to claim 17, further comprising the return conductor entirely under the subject's skin, the return conductor comprising sufficient length to extend, once implanted, from the target tissue to subcutaneous tissue located below the surface anodic electrode, the return conductor having a collecting end and a returning end and being insulated between its ends, the collecting end forming an electrical termination having a sufficient surface area to allow a portion of the current delivered to the target body tissue to return through the return conductor in preference to returning through body tissue, and the returning end forming an electrical termination that returns the electrical current to the surface anodic electrode via the subcutaneous tissue and skin underlying that electrode.

19. The method according to claim 17, further comprising implanting a plurality of implants as defined in claim 17 for electrically stimulating more than one target body tissue independently or in unison, each implant being implanted entirely under the subject's skin and being of a sufficient length to extend to a different target body tissue, and positioning a plurality of surface cathodic and one or more surface anodic electrodes appropriately relative to the implants to stimulate the different target body tissues independently or in unison.

20. The method according to claim 17, 18 or 19, wherein the conductor is formed from a metal wire, carbon fibers, a conductive rubber or other conductive polymer, or a conductive salt solution in rubber.

21. The method according to claim 20, wherein the terminations on one or both of the pick-up end or stimulating end provide an enlarged surface in the form of a coil, a spiral, a cuff, a rod, or a plate or sheet in the form of an oval or polygon.

22. The method according to claim 21, wherein the surface cathodic and anodic electrodes comprise a conductive plate or sheet, a conductive gel electrode, a conductive rubber or polymer electrode that may be paitially covered with an electrode paste or gel, or a moistened absorbent pad electrode.

23. The method according to claim 21, wherein the terminations can be formed from uninsulated ends of the conductor itself, or from other conductive or capacitive materials.

24. The method according to claim 21, further comprising a conductive or capacitive coating, or oxide layer on one or both of the terminations.

25. The method according to claim 21, further comprising a coating on one or both of the terminations for providing an anti-inflammatory, anti-bacterial or growth effect, the coating being a substance selected from the group consisting of an anti-inflammatory agent, an antibacterial agent, an antibiotic, and a tissue ingrowth promoter.

26. The method according to claim 17, 18 or 19, wherein the body tissue is selected from a neural tissue in the peripheral or central nervous system, a nerve, a muscle or an organ.

27. The method according to claim 17, 18 or 19, wherein stimulation of the body tissue is conducted to treat a condition selected from the group consisting of a movement disorder, a muscular disorder, incontinence, urinary retention, pain, epilepsy, a cerebrovascular disorder, a sleep disorder, an autonomic disorder, a disorder of vision, hearing or balance, and a neuropsychiatric disorder, to promote bone growth or wound healing, or to promote tissue regeneration.