Systems and methods for producing asynchronous neural responses to treat pain and/or other patient conditions
Systems and methods for producing asynchronous neural responses to treat pain and/or other patient conditions are disclosed. A method in accordance with a particular embodiment includes selecting a target stimulation frequency that is above a threshold frequency, with the threshold frequency corresponding to a refractory period for neurons of a target sensory neural population. The method can further include producing a patient sensation of paresthesia by directing an electrical signal to multiple sensory neurons of the target sensory neural population at the stimulation frequency, with individual neurons of the sensory neural population completing corresponding individual refractory periods at different times, resulting in an asynchronous sensory neuron response to the electrical signal.
1. A system for producing an asynchronous neural response, comprising:
a pulse generator having a machine-readable medium containing instructions that, when executed, cause the pulse generator to—
(a) transmit a first electrical stimulation signal having a first frequency, and a second electrical stimulation signal having a second frequency, wherein—
the first frequency is less than one half of a target stimulation frequency sufficient to produce the asynchronous neural response, and
the second frequency is less than one half of the target stimulation frequency, and
(b) transmit a plurality of paired pulses that produce the asynchronous neural response, wherein individual paired pulses comprise a first pulse of the first electrical stimulation signal separated by a phase shift from a second pulse of the second electrical stimulation signal; and
a signal delivery element couplable to the pulse generator to deliver the first electrical stimulation signal and the second electrical stimulation signal to a target neural population.
2. The system of claim 1 wherein the instructions further cause the pulse generator to transmit an initial electrical stimulation signal, prior to transmittal of the first electrical stimulation signal and the second electrical stimulation signal, and wherein the initial electrical stimulation signal has a frequency equal to the target stimulation frequency.
3. The system of claim 2 wherein the target stimulation frequency is at least an order of magnitude greater than a threshold frequency corresponding to a refractory period for neurons of the target neural population.
4. The system of claim 1 wherein the individual paired pulses have a corresponding combined period equal to the time between a start of the first pulse and a start of a second pulse, and wherein the inverse of the combined period is greater than 3.0 kHz.
5. The system of claim 1 wherein consecutive individual paired pulses are separated by a quiescent period, and wherein the quiescent period is longer than the phase shift.
6. The system of claim 5 wherein the quiescent period is less than a refractory period for the target neural population.
7. The system of claim 1 wherein the first electrical stimulation signal has a first amplitude, and the second electrical stimulation signal has a second amplitude greater than the first amplitude.
8. The system of claim 1 wherein the instructions, when executed, further cause the pulse generator to transmit a generally constant stream of pulses during a first period of time to initiate the asynchronous neural response, and wherein the paired pulses are delivered during a second period in time, after the first period of time, to extend the duration of the asynchronous neural response.
9. The system of claim 8 wherein the individual paired pulses have a first spacing therebetween, and wherein the stream of pulses have a second spacing therebetween that is different than the first spacing.
10. The system of claim 8 wherein the paired pulses comprise pulses of the first and second electrical stimulation signals interleaved with one another such that individual pulses of the first electrical stimulation signal are followed by individual pulses of the second electrical stimulation signal, and individual pulses of the second electrical stimulation signal are followed by individual pulses of the first electrical stimulation signal.
11. The system of claim 8 wherein the target stimulation frequency is in a range from about 3 kHz to about 10 kHz, and wherein the paired pulses have a frequency at or above the target stimulation frequency.
12. A method for configuring a stimulation device to produce an asynchronous neural response, the method comprising:
determining a target stimulation frequency based on a threshold frequency corresponding to a refractory period for neurons of a target sensory neural population, wherein the target stimulation frequency is greater than the threshold frequency; and
programming the stimulation device to deliver a first electrical stimulation signal having a plurality of first pulses at a first frequency, and a second electrical stimulation signal having a plurality of second pulses at a second frequency, wherein the first frequency and the second frequency are less than one half of the target stimulation frequency, and wherein the stimulation device is programmed to deliver the first pulses at an offset from the second pulses to produce the asynchronous neural response.
13. The method of claim 12 wherein the target stimulation frequency is in a range from 3.0 kHz to 10 kHz.
14. The method of claim 13 wherein the offset produces a paired pulse having an individual first pulse from the first electrical stimulation signal and an individual second pulse from the second electrical stimulation signal, wherein the paired pulse has a combined period equal to the time between a start of the individual first pulse and a start of the individual second pulse, and wherein the inverse of the combined period is greater than 3.0 kHz.
15. The method of claim 14 wherein the inverse of the combined period is at least an order of magnitude greater than the threshold frequency.
16. The method of claim 12 wherein the offset produces a plurality of paired pulses, and wherein consecutive individual paired pulses are separated by a quiescent period that is greater than the offset.
17. The method of claim 16 wherein the quiescent period is less than a refractory period for a target neural population.
18. The method of claim 12 , further comprising programming the stimulation device to deliver a continuous stream of pulses at the target stimulation frequency prior to delivering the first electrical stimulation signal and the second electrical stimulation signal.
19. The method of claim 12 , further comprising programming the stimulation device to deliver the first electrical stimulation signal at a first amplitude, and to deliver the second electrical stimulation signal at a second amplitude, wherein the second amplitude is greater than the first amplitude.
20. A system for initiating and maintaining an asynchronous neural response, the system comprising:
an implantable pulse generator having a machine-readable medium containing instructions that, when executed, cause the pulse generator to:
transmit an initial electrical stimulation signal to initiate the asynchronous neural response in a target neural population, wherein the initial electrical stimulation signal is transmitted at a target stimulation frequency, and wherein the target stimulation frequency is greater than a threshold frequency for the target neural population;
subsequent to transmitting the initial electrical stimulation signal, transmit a first electrical stimulation signal having a first frequency, wherein the first frequency is less than one half of the target stimulation frequency; and
concurrent with transmitting the first electrical stimulation signal, transmit a second electrical stimulation signal having a second frequency, wherein the second frequency is less than one half of the target stimulation frequency, wherein the first electrical stimulation signal and the second electrical stimulation signal are transmitted with an offset, wherein the offset is less than a refractory period for neurons of the target neural population, and wherein the offset is selected to maintain the asynchronous neural response; and
an implantable lead having a plurality of electrodes, wherein the lead is positionable to deliver the initial electrical stimulation signal, the first electrical stimulation signal, and the second electrical stimulation signal to the target neural population.
21. The system of claim 20 wherein the target stimulation frequency is at least 3.0 kHz.
22. The system of claim 21 wherein the threshold frequency is less than 1000 Hz.
23. The system of claim 20 wherein the first electrical stimulation signal and the second electrical stimulation signal comprise a plurality of paired pulses, wherein consecutive paired pulses are separated by a quiescent period, and wherein the quiescent period is greater than the offset and less than the refractory period.
24. The system of claim 23 wherein the first frequency is not equal to the second frequency.