Apparatus and methods for stimulating tissue

1 . A method, comprising the steps of:

generating action potentials in neural fibers in first and second neural fiber bundles with a first electrode that is a first distance from the first neural fiber bundle and is a second distance, that is greater than the first distance, from the second neural fiber bundle; and

blocking at least some of the action potentials in the first neural fiber bundle with a second electrode that is the first distance from the first neural fiber bundle and the second distance from the second neural fiber bundle.

2 . A method as claimed in claim 1 , wherein

generating action potentials comprises sinking a portion of current from the second electrode at the first electrode;

and further comprising the step of:

sinking another portion of the current from the second electrode at a remote electrode.

3 . A method as claimed in claim 1 , wherein blocking at least some of the action potentials comprises blocking at least some of the action potentials in the first neural fiber bundle with second and third electrodes that are each the first distance from the first neural fiber bundle and the second distance from the second neural fiber bundle and are located on opposite sides of the first electrode.

4 . A method as claimed in claim 3 , wherein

generating action potentials comprises sinking a portion of current from the second and third electrodes at the first electrode;

and further comprising the step of:

sinking another portion of the current from the second and third electrode at a remote electrode.

5 . A neurostimulation system for use with a first implantable lead including a plurality of lead electrodes, the neurostimulation system comprising:

an implanted pulse generator (IPG) including a lead connector;

circuitry, operably connected to the lead connector, to generate electrical waveforms that create action potentials in neural fibers in first and second neural fiber bundles with a first lead electrode, the first neural fiber bundle being a first distance from the first implantable lead and the second neural fiber bundle being a second distance, that is greater than the first distance, from the first implantable lead; and

circuitry, operably connected to the lead connector, that generates electrical waveforms to block at least some of the action potentials in the first neural fiber bundle with a second lead electrode.

6 . A neurostimulation system as claimed in claim 5 ,

further comprising a remote electrode;

wherein the circuitry generating electrical waveforms to block at least some of the action potentials comprises circuitry to source current at the second lead electrode; and

wherein the circuitry to generate electrical waveforms to create action potentials comprises circuitry to sink a portion of the current from the second lead electrode at the first lead electrode and to sink a portion of the current from the second lead electrode at the remote electrode.

7 . A neurostimulation system as claimed in claim 5 , wherein

the IPG includes a case electrode;

the circuitry generating electrical waveforms to block at least some of the action potentials comprises circuitry to source current at the second lead electrode; and

the circuitry to generate electrical waveforms to create action potentials comprises circuitry to sink a portion of the current from the second lead electrode at the first lead electrode and to sink a portion of the current from the second lead electrode at the case electrode.

8 . A neurostimulation system as claimed in claim 5 , wherein

the circuitry generating electrical waveforms to block at least some of the action potentials comprises circuitry to generate electrical waveforms to block at least some of the action potentials in the first neural fiber bundle with second and third lead electrodes located on opposite sides of the first lead electrode.

9 . A neurostimulation system as claimed in claim 8 , wherein

the circuitry generating electrical waveforms to block at least some of the action potentials comprises circuitry to source current at the second and third lead electrodes; and

the circuitry to generate electrical waveforms to create action potentials comprises circuitry to sink a portion of the current from the second and third lead electrodes at the first lead electrode and to sink a portion of the current from the second and third lead electrodes at a remote electrode.

10 . A neurostimulation system as claimed in claim 8 , wherein

the IPG includes a case electrode;

the circuitry generating electrical waveforms to block at least some of the action potentials comprises circuitry to source current at the second and third lead electrodes; and

the circuitry to generate electrical waveforms to create action potentials comprises circuitry to sink a portion of the current from the second and third lead electrodes at the first lead electrode and to sink a portion of the current from the second and third lead electrodes at the case electrode.

11 . A neurostimulation system for use with a first implantable lead including a plurality of lead electrodes, the neurostimulation system comprising:

an implanted pulse generator (IPG) including a lead connector and a case electrode;

circuitry, operably connected to the lead connector, to source current at a first lead electrode; and

circuitry, operably connected to the lead connector and the case electrode, to sink a portion of the current from the first lead electrode at a second lead electrode and to sink a portion of the current from the first lead electrode at the case electrode.

12 . A neurostimulation system as claimed in claim 11 , wherein

the circuitry to source current comprises circuitry to source current at first and third lead electrodes located on opposite sides of the second lead electrode; and

the circuitry to sink current comprises circuitry to sink a portion of the current from the first and third lead electrodes at the second lead electrode and to sink another portion of the current from the first and third lead electrodes at the case electrode.

13 . A neurostimulation system as claimed in claim 12 , wherein

the circuitry to source current comprises circuitry to source equal amounts of current at the first and third lead electrodes.

14 . A method, comprising the steps of:

sourcing current into neural tissue with a first electrode on an implantable lead;

sinking a portion of the current from the first electrode at a second electrode on the implantable lead; and

sinking another portion of the current from the first electrode at a remote electrode.

15 . A method as claimed in claim 14 , wherein

sourcing current into neural tissue comprises sourcing current into neural tissue with first and third electrodes located on the implantable lead and on opposite sides of the second electrode.

16 . A method as claimed in claim 15 , wherein

all of the current sourced at the first and third electrodes is sunk at the second electrode and the remote electrode.

17 . A method as claimed in claim 14 , wherein

sinking a portion of the current from the first electrode at a second electrode comprises sinking current sufficient to generate action potentials in the neural tissue at the second electrode.

18 . A method as claimed in claim 14 , wherein

sourcing current into neural tissue with first electrode comprises sourcing current sufficient to block action potentials at the first electrode.

19 . A method as claimed in claim 14 , wherein

sinking another portion of the current from the first electrode comprises sinking another portion of the current from the first electrode at a case electrode.

20 . A method as claimed in claim 14 , wherein the neural tissue comprises elongate fibers, the method further comprising the step of:

orienting the implantable lead transverse to the elongate fibers.