System and method for coupling burst and tonic stimulation

1. A method for controlling burst stimulation of nervous tissue of a patient, the method comprising:

providing a lead having at least one electrode on the lead configured to be implanted at a target position proximate to nervous tissue of interest;

delivering a first current pulse configured as a tonic stimulation waveform to the at least one electrode, the tonic stimulation waveform configured to excite A-beta fibers of the nervous tissue;

after a tonic-burst delay, delivering second current pulses configured as a burst stimulation waveform to the at least one electrode, the burst stimulation waveform configured to excite C-fibers of the nervous tissue; and

adjusting the tonic-burst delay between the tonic and burst stimulation waveforms to deliver the burst stimulation waveform during a refractory period of the A-beta fibers excited by the tonic stimulation waveform to avoid excitation of the A-beta fibers excited by the tonic stimulation waveform.

2. The method of claim 1 , wherein the current pulses of the burst stimulation waveform are delayed by a predetermined initial delay following the current pulse of the tonic stimulation waveform, the predetermined initial delay representing the tonic-burst delay and being programmed by a clinician.

3. The method of claim 1 , wherein the tonic stimulation waveform represents a biphasic waveform and the burst stimulation waveform represents a series of monophasic pulses.

4. The method of claim 1 , wherein the tonic stimulation waveform is biphasic with first and second phase pulses, the first phase pulse configured to capture at least a portion of the A-beta fibers to deliver a first pain relief, the second phase pulse configured to repolarize charge at a stimulation site to limit excitation of A-beta fibers.

5. The method of claim 1 , further comprising sensing signals at the at least one electrode on the lead, and analyzing the signals to identify a C-fiber sensory action potential (C-fiber SAP) component of the signals.

6. The method of claim 5 , further comprising adjusting the tonic-burst delay based on the C-fiber SAP component of the signals.

7. The method of claim 6 , wherein the adjusting operation includes adjusting the tonic-burst delay to reduce the C-fiber SAP component.

8. The method of claim 5 , further comprising analyzing a feature of interest from a morphology of the C-fiber SAP component over time, counting a number of occurrences of the feature of interest that occur within the C-fiber SAP component over a predetermined duration, comparing the number of occurrences to a prior number of occurrences, and adjusting the tonic-burst delay based on the comparing operation.

9. The method of claim 5 , further comprising analyzing the C-fiber SAP component to determine SAP activity level data for a present coupled tonic-burst therapy.

10. The method of claim 1 , wherein the at least one electrode comprises a plurality of electrodes; and wherein the delivering operation comprises delivering the tonic stimulation waveform to a first sub-set of the electrodes and the burst stimulation waveform to a second sub-set of the electrodes, the first and second sub-sets have at least one unique electrode relative to each other.

11. The method of claim 1 , wherein the at least one electrode includes a microelectrode located immediately adjacent C-fibers, the method further comprising sensing a C-fiber sensory action potential (SAP) directly at the microelectrode and performing an iterative feedback loop to adjust at least one therapy parameter for a coupled tonic-burst therapy based on the C-fiber SAP.

12. A system for coupling burst and tonic stimulation, the system comprising:

a lead having at least one stimulation electrode, the lead configured to be implanted at a target position proximate to nervous tissue of interest; and

an implantable pulse generator (IPG) coupled to the lead, the IPG configured to:

deliver a first current pulse configured as a tonic stimulation waveform to the at least one electrode, the tonic stimulation waveform configured to excite A-beta fibers of the nervous tissue;

after a tonic-burst delay, deliver second current pulses configured as a burst stimulation waveform to the at least one electrode, the burst stimulation waveform configured to excite C-fibers of the nervous tissue; and

adjust the tonic-burst delay between the tonic and burst stimulation waveforms to deliver the burst stimulation waveform during a refractory period of the A-beta fibers excited by the tonic stimulation waveform to avoid excitation of the A-beta fibers excited by the tonic stimulation waveform.

13. The system of claim 12 , wherein the lead includes a plurality of electrodes, and the IPG is configured to deliver the tonic stimulation waveform to a first sub-set of the electrodes and the burst stimulation waveform to a second sub-set of the electrodes, the first and second sub-sets have at least one unique electrode relative to each other.

14. The system of claim 12 , wherein the at least one electrode includes a microelectrode configured to be located immediately adjacent C-fibers and configured to sense a C-fiber sensory action potential (SAP) directly at the microelectrode.

15. The system of claim 11 , wherein the at least one electrode on the lead senses signals and the processor analyzes the signals to identify a C-fiber sensory action potential (C-fiber SAP) component of the signals.

16. The system of claim 15 , wherein the processor is configured to adjust the tonic-burst delay based on the C-fiber SAP component of the signals.

17. The system of claim 15 , wherein the processor is configured to adjust the tonic-burst delay to reduce the C-fiber SAP component.

18. The system of claim 15 , wherein the processor is configured to analyze a feature of interest from a morphology of the C-fiber SAP component over time, count a number of occurrences of the feature of interest that occur within the C-fiber SAP component over a predetermined duration, compare the number of occurrences to a prior number of occurrences, and adjust the tonic-burst delay based on the comparing operation.

19. The system of claim 15 , wherein the processor is configured to analyze the C-fiber SAP component to determine SAP activity level data for a present coupled tonic-burst therapy.

20. The system of claim 11 , wherein the at least one electrode comprises a plurality of electrodes; and wherein the processor is configured to deliver the tonic stimulation waveform to a first sub-set of the electrodes and the burst stimulation waveform to a second sub-set of the electrodes, the first and second sub-sets have at least one unique electrode relative to each other.