Implantable microstimulators and methods for unidirectional propagation of action potentials

• US 20040015204A1
• Filed: 06/20/2002
• Published: 01/22/2004
• Est. Priority Date: 06/20/2002
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Carbunaru, Rafael, Whitehurst, Todd K., Haller, Matthew I., McGivern, James P., Bradley, Kerry, He, Tom Xiaohai, Kuzma, Janusz A.
• Granted Patent: US 7,860,570 B2
• Time in Patent Office: Days
• US Class Current: 607/48
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0556 Cuff electrodes
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient

Abstract

Miniature implantable stimulators (i.e., microstimulators) are capable of producing unidirectionally propagating action potentials (UPAPs). The methods and configurations described may, for instance, arrest action potentials traveling in one direction, arrest action potentials of small diameters nerve fibers, arrest action potentials of large diameter nerve fibers. These methods and systems may limit side effects of bidirectional and/or less targeted stimulation.

Claims

1. A method for arresting propagation of action potentials in one direction along a nerve, comprising:

providing a microstimulator with at least a first cathode and a first anode;

applying a relatively high-amplitude depolarizing cathodic current to a nerve via the first cathode, which cathodic current initiates bidirectional action potentials in large diameter nerve fibers and small diameter nerve fibers;

before the action potentials pass the first anode, applying a relatively high-amplitude hyperpolarizing anodic current to the nerve via the first anode at a side of the cathode where arrest of action potentials is desired, which high-amplitude anodic current arrests action potentials in large diameter nerve fibers and small diameter nerve fibers; and

tapering the anodic current.

2. The method of claim 1 wherein providing a microstimulator with a first cathode and a first anode comprises providing a programmably configurable microstimulator with at least two activated electrodes configured as the first cathode and the first anode.

3. The method of claim 1 wherein the hyperpolarizing anodic current is of the same amplitude and duration as the depolarizing cathodic current.

4. The method of claim 1 wherein the hyperpolarizing anodic current is at least one of higher in amplitude and of longer duration than the depolarizing cathodic current.

5. The method of claim 1 wherein the relatively high-amplitude depolarizing cathodic current is applied at an amplitude of about 0.01 mA to about 15 mA and a pulse width of about 0.01 msec to about 5.0 msec and the relatively high-amplitude hyperpolarizing anodic current is applied at an amplitude of about 0.1 mA to about 15 mA and a pulse width of about 0.05 msec to about 10.0 msec.

6. The method of claim 1 further comprising:

providing at least a second anode; and

applying a lower amplitude anodic current to the nerve via the second anode at the side of the cathode where propagation of action potentials is desired, which lower amplitude anodic current reduces a virtual cathode created near the first anode.

7. The method of claim 6 wherein providing a microstimulator with a first cathode and a first anode and a second anode comprises providing a programmably configurable microstimulator with at least three activated electrodes programmably configured as the first cathode and the first anode and the second anode.

8. The method of claim 6 wherein the relatively high-amplitude depolarizing cathodic current is applied at an amplitude of about 0.01 mA to about 15 mA and a pulse width of about 0.01 msec to about 5.0 msec and the relatively high-amplitude hyperpolarizing anodic current is applied at an amplitude of about 0.1 mA to about 15 mA and a pulse width of about 0.05 msec to about 10.0 msec and the lower amplitude anodic current is applied at an amplitude of about 0.01 mA to about 10 mA and a pulse width of about 0.01 msec to about 5.0 msec.

9. The method of claim 1 wherein the microstimulator includes a fixation device.

10. The method of claim 9 wherein the fixation device includes a nerve cuff.

11. The method of claim 1 wherein the microstimulator includes at least one lead.

12. The method of claim 1 further comprising applying the relatively high-amplitude hyperpolarizing anodic current to a more distal portion of the nerve than the relatively high-amplitude cathodic current, thereby effectively selecting afferent fibers of the nerve.

13. The method of claim 1 further comprising applying the relatively high-amplitude hyperpolarizing anodic current to a more proximal portion of the nerve than the relatively high-amplitude cathodic current, thereby effectively selecting efferent fibers of the nerve.

14. The method of claim 1 further comprising sensing a physical condition of a patient and adjusting the application of currents to the nerve based on the sensed physical condition.

15. The method of claim 14 wherein the sensed physical condition of the patient comprises the action potentials propagating along the nerve.

16. A method for arresting propagation of action potentials in small diameter nerve fibers, comprising:

providing a microstimulator with at least a first cathode and a first anode;

applying a depolarizing cathodic current to a nerve via the first cathode, which current initiates bidirectional action potentials in small diameter nerve fibers and large diameter nerve fibers;

waiting an amount of time allowing the action potentials to propagate in the large diameter nerve fibers;

applying a hyperpolarizing anodic current to the nerve via the first anode at a side of the cathode where arrest of action potentials in the small diameter nerve fibers is desired, which current arrests action potentials in the small diameter nerve fibers;

tapering the anodic current.

17. The method of claim 16 wherein providing a microstimulator with at least a first cathode and a first anode comprises providing a programmably configurable microstimulator with at least two activated electrodes configured as the first cathode and the first anode.

18. The method of claim 16 further comprising:

providing at least one additional anode; and

applying at least one additional anodic current via the at least one additional anode, which additional anodic current inhibits stimulation at a virtual cathode.

19. The method of claim 18 wherein providing a microstimulator with a first cathode and a first anode and at least one additional anode comprises providing a programmably configurable microstimulator with at least three activated electrodes programmably configured as the first cathode and the first anode and the additional anode.

20. The method of claim 16 wherein the side of the cathode where arrest of action potentials in the small diameter nerve fibers is desired comprises more than one side of the cathode and further comprising applying the hyperpolarizing anodic current via the first anode and the additional anode.

21. The method of claim 16 wherein the microstimulator includes a fixation device.

22. The method of claim 16 further comprising sensing a physical condition of a patient and adjusting the application of currents to the nerve based on the sensed physical condition.

23. The method of claim 22 wherein the sensed physical condition of the patient comprises the action potentials propagating along the nerve.

24. The method of claim 23 wherein the sensed action potentials are used to determine the amount of time to wait to allow the action potentials to propagate in the large diameter nerve fibers.

25. A method for arresting propagation of action potentials in large diameter nerve fibers, comprising:

providing a microstimulator with at least a first cathode and a first anode;

applying a relatively high-amplitude depolarizing cathodic current to a nerve via the first cathode, which current initiates bidirectional action potentials in small diameter nerve fibers and large diameter nerve fibers;

applying a relatively low-amplitude hyperpolarizing anodic current to the nerve via the first anode at a side of the cathode where arrest of action potentials in the large diameter nerve fibers is desired, which current arrests action potentials in large diameter nerve fibers and allows propagation of action potentials in small diameter nerve fibers;

tapering the anodic current.

26. The method of claim 25 wherein providing a microstimulator with at least a first cathode and a first anode comprises providing a programmably configurable microstimulator with at least two activated electrodes configured as the first cathode and the first anode.

27. The method of claim 25 further comprising:

providing at least one additional anode; and

applying at least one additional anodic current via the at least one additional anode, which additional anodic current inhibits stimulation at a virtual cathode by reducing current flow from the first anode to the first cathode.

28. The method of claim 27 wherein providing a microstimulator with a first cathode and a first anode and at least one additional anode comprises providing a programmably configurable microstimulator with at least three activated electrodes programmably configured as the first cathode and the first anode and the additional anode.

29. The method of claim 25 wherein the side of the cathode where arrest of action potentials in large diameter nerve fibers is desired comprises more than one side of the cathode and further comprising applying the hyperpolarizing anodic current via the first anode and the second anode.

30. The method of claim 25 wherein the microstimulator includes a fixation device.

31. A method of stimulating a nerve, comprising:

providing at least one implantable microstimulator with at least two electrodes, wherein the electrodes comprise at least a first cathode and a first anode;

configuring the electrodes to apply stimulation that unidirectionally propagates action potentials of a nerve;

applying the stimulation to the nerve to effectively select orthodromic action potentials traveling in one direction along the nerve, thereby limiting side effects of bidirectional stimulation.

32. The method of claim 31, further comprising:

applying a depolarizing cathodic current to a nerve via the first cathode, which cathodic current initiates bidirectional action potentials in large diameter nerve fibers and small diameter nerve fibers;

applying a hyperpolarizing anodic current to the nerve via the first anode at a side of the cathode where arrest of action potentials is desired; and

tapering the anodic current.

33. The method of claim 32 wherein the hyperpolarizing current is relatively high-amplitude hyperpolarizing current, which high-amplitude hyperpolarizing current arrests action potentials in large diameter nerve fibers and small diameter nerve fibers.

34. The method of claim 32 further comprising waiting an amount of time allowing the action potentials to propagate in the large diameter nerve fibers, then applying the hyperpolarizing anodic current to the nerve at the side of the cathode where arrest of action potentials in the small diameter nerve fibers is desired, which hyperpolarizing current arrests action potentials in the small diameter nerve fibers.

35. The method of claim 32 further comprising applying the hyperpolarizing current before the action potentials pass the first anode, which hyperpolarizing current is a relatively low-amplitude hyperpolarizing current, which low-amplitude hyperpolarizing current arrests action potentials in large diameter nerve fibers and allows propagation of action potentials in small diameter nerve fibers.

36. The method of claim 31 wherein the microstimulator includes a fixation device.

37. The method of claim 36 wherein the fixation device includes a nerve cuff.

38. The method of claim 31 further comprising sensing a physical condition of a patient and adjusting the application of stimulation to the nerve based on the sensed physical condition.

39. The method of claim 38 wherein the sensed physical condition of the patient comprises the action potentials propagating along the nerve.

40. The method of claim 39 wherein the sensed action potentials are used to determine the stimulation to apply to the nerve, and wherein determining the stimulation to apply includes determining the timing of the stimulation.

41. A system for directing action potentials unidirectionally, comprising:

a microstimulator including;

at least one cathode;

at least two anodes, configured with the at least one cathode between the at least two anodes;

electrical circuitry electrically connected to the at least one cathode and at least two anodes, wherein the electrical circuitry generates electric current applied by the cathodes and anodes;

programmable memory connected to the electrical circuitry, which programmable memory stores parameters determining the electric current generated by the electrical circuitry and applied by the cathodes and anodes; and

a power source providing operating power to at least the electrical circuitry;

wherein the electric current generated and applied by the microstimulator comprises at least one depolarizing current and at least one hyperpolarizing current.

42. The system of claim 41 wherein the depolarizing current triggers action potentials in a first direction and in a second direction and the at least one hyperpolarizing current interrupts the action potentials in at least one of the first direction and second direction, thereby allowing the action potentials to propagate in one direction.

43. The system of claim 41 further including a lead, which lead is used for positioning at least one of a cathode and an anode.

44. The system of claim 41 further including a nerve cuff, which cuff is used for positioning at least one of a cathode and an anode.

45. The system of claim 41 further including a fixation device, which fixation device is used for positioning at least one of a cathode and an anode.

46. The system of claim 45 wherein the fixation device includes a nerve cuff.

47. The system of claim 41 further including at least one sensor for sensing at least one physical condition of a patient.

48. The system of claim 47 further comprising circuitry using the sensed physical condition to adjust the parameters determining the electric currents.

49. The system of claim 48 wherein sensing at least one physical condition of the patient comprises sensing action potentials.

50. The system of claim 41 wherein the microstimulator further includes programmably configurable electrodes, wherein at least three electrodes are activated and configured as the at least one cathode and the at least two anodes.