阅读说明：本技术 使用交替极性的单相脉冲和被动电荷恢复进行的脊髓刺激 (Spinal cord stimulation using monophasic pulses of alternating polarity and passive charge recovery ) 是由 奎·T·多恩 卢卡·安东内洛·安内奇诺 伊斯梅尔·赫尔塔斯·费尔南德斯 于 2020-01-13 设计创作，主要内容包括：公开了用于在可植入脉冲发生器或外部试验刺激器中使用的新的波形,该波形模拟主动驱动的双相脉冲,并且特别地用于发出低频率脉冲。波形在每个电极处包括交错的第一脉冲和第二脉冲。每个第一脉冲包括第一单相脉冲和第一被动电荷恢复时段。每个第二脉冲包括具有与第一单相脉冲相反的极性的第二单相脉冲和第二被动电荷恢复时段。优选地,第一单相脉冲和第二单相脉冲的幅值和脉宽相等,或者至少在每个电极处电荷平衡。第一单相脉冲和第二单相脉冲模仿对称双相脉冲的功能,其中第一单相脉冲模仿双相脉冲的第一阶段的功能,并且其中第二单相脉冲模仿双相脉冲的第二阶段的功能。(Novel waveforms for use in an implantable pulse generator or external trial stimulator are disclosed that simulate actively driven biphasic pulses, and in particular for delivering low frequency pulses. The waveform includes interleaved first and second pulses at each electrode. Each first pulse includes a first monophasic pulse and a first passive charge recovery period. Each second pulse includes a second monophasic pulse having a polarity opposite to that of the first monophasic pulse and a second passive charge recovery period. Preferably, the first monophasic pulse and the second monophasic pulse are equal in amplitude and pulse width, or at least charge balanced at each electrode. The first monophasic pulse and the second monophasic pulse mimic the function of a symmetric biphasic pulse, wherein the first monophasic pulse mimics the function of a first phase of a biphasic pulse, and wherein the second monophasic pulse mimics the function of a second phase of a biphasic pulse.)

1. A stimulator device, comprising:

a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient; and

stimulation circuitry configured by stimulation parameters to provide a repeating sequence of interleaved first and second pulses at least two of the electrode nodes to create a stimulation current through tissue of the patient via the first and second pulses,

wherein, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity and a first passive charge recovery pulse of a second polarity opposite to the first polarity, the first passive charge recovery pulse being configured to recover charge stored during the first monophasic pulse, and

wherein, at the first electrode node, each second pulse comprises a second monophasic pulse of the second polarity and a second passive charge recovery pulse of the first polarity, the second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

2. The stimulator device according to claim 1, wherein the first passive recovery pulse immediately follows the first of the first pulses at the first electrode node, and wherein the second passive recovery pulse immediately follows the second of the second pulses at the first electrode node.

3. The stimulator device according to claim 1 or 2, wherein the first monophasic pulse has a first amplitude and a first pulse width, and wherein the second monophasic pulse has a second amplitude and a second pulse width.

4. The stimulator device as defined by claim 3, wherein the first and second amplitudes are equal, and wherein the first and second pulse widths are equal.

5. The stimulator device as defined in any one of claims 1 to 4, wherein the first monophasic pulse and the second monophasic pulse are charge balanced at the first electrode node.

6. The stimulator device according to any one of claims 1 to 5, wherein the stimulation circuitry includes one or more digital-to-analog converters (DACs) configured to actively drive the first monophasic pulse and the second monophasic pulse at the first electrode node.

7. The stimulator device according to claim 6, wherein the stimulation circuitry includes a plurality of passive recovery switches each coupled between one of the electrode nodes and a reference potential, wherein the first and second passive charge recovery pulses are formed by closing the passive recovery switch coupled to the first electrode node, wherein the one or more DACs are not configured to actively drive the first and second passive charge recovery pulses.

8. The stimulator device according to claim 6 or 7, wherein the one or more DACs include one or more Positive DACs (PDACs) configured to provide current and one or more Negative DACs (NDACs) designed to absorb current, wherein the first monophasic pulse is actively driven by at least one PDAC of the one or more PDACs at the first electrode node, and wherein the second monophasic pulse is actively driven by at least one NDAC of the one or more NDACs at the first electrode node.

9. The stimulator device as defined in any one of claims 1 to 8, wherein the second pulse is centered in time with respect to the first pulse at the first electrode node.

10. Stimulator device as claimed in any one of the claims 1 to 9,

wherein at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity and a third passive charge recovery pulse of the first polarity, the third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse,

wherein, at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity and a fourth passive charge recovery pulse of the second polarity configured to recover charge stored during the fourth monophasic pulse.

11. The stimulator device according to claim 10, wherein the first monophasic pulse and the third monophasic pulse are temporally coincident, wherein the second monophasic pulse and the fourth monophasic pulse are temporally coincident, wherein the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident.

12. The stimulator device as defined by claim 10 or 11, further comprising a housing for housing the stimulation circuitry, wherein the housing is electrically conductive and includes one of the plurality of electrodes, wherein the second electrode node comprises an electrode node coupled to the electrically conductive housing.

13. The stimulator device according to any one of claims 1 to 12, wherein an interval period during which no stimulation current flows is between (i) the first monophasic pulse and the first passive charge recovery pulse in each first pulse, and (ii) the second monophasic pulse and the second passive charge recovery pulse in each second pulse.

14. The stimulator device as defined in any one of claims 1 to 13, wherein the first pulse is issued at a first frequency at the first electrode node, and wherein the second pulse is issued at the first electrode node at the first frequency.

15. The stimulator device as claimed in any one of claims 1 to 14, wherein each electrode node is coupled to its associated electrode by a DC blocking capacitor.

16. A system, comprising:

a stimulator device comprising a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient; and

an external device for programming the stimulator device, comprising a non-transitory computer readable medium containing a software program, wherein the software program when executed on the external device is configured to:

presenting a Graphical User Interface (GUI) on the external device,

receiving at the (GUI) stimulation parameters of pulses to be produced at least two of the electrode nodes in the stimulator device,

automatically deriving a waveform from the stimulation parameters, wherein the waveform comprises interleaved first and second pulses at the at least two electrode nodes,

wherein in the automatically derived waveform, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity followed by a first passive charge recovery pulse configured to recover charge stored during the first monophasic pulse, and

wherein in the automatically derived waveform, at the first electrode node, each second pulse comprises a second monophasic pulse of a second polarity opposite the first polarity, followed by a second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

17. The system of claim 16, wherein the stimulation parameters do not independently specify the interleaved first and second pulses.

18. The system according to claim 16 or 17,

wherein in the automatically derived waveform, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity followed by a third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse,

wherein in the automatically derived waveform, at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity followed by a fourth passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

19. The system of claim 18, wherein the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time.

20. The system of claim 19, wherein the first passive charge recovery pulse and the third passive charge recovery pulse are coincident in time, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are coincident in time.

21. The system according to any one of claims 16 to 20, wherein the software program, when executed on the external device, is further configured to transmit the derived waveform to the stimulator device to generate pulses at the at least two of the electrode nodes.

22. The system of any of claims 16 to 21, wherein the GUI includes a user selectable option to automatically derive the waveform from the stimulation parameters.

Technical Field

The present application relates to Implantable Medical Devices (IMDs), typically spinal cord stimulators, and more particularly to methods of controlling such devices.

Background

Implantable neurostimulator devices are devices that generate and deliver electrical stimulation to bodily nerves and tissues for treatment of various biological diseases, such as pacemakers for treating cardiac arrhythmias, defibrillators for treating cardiac fibrillation, cochlear stimulators for treating deafness, retinal stimulators for treating blindness, muscle stimulators for producing coordinated limb movements, spinal cord stimulators for treating chronic pain, cortical and deep brain stimulators for treating motor and psychological diseases, and other neurostimulators for treating urinary incontinence, sleep apnea, shoulder subluxation, and the like. The following description will generally focus on the use of the present invention in a Spinal Cord Stimulation (SCS) system, such as the system disclosed in U.S. patent 6,516,227. However, the present invention may be applicable to any implantable neurostimulator device system.

SCS systems generally include an Implantable Pulse Generator (IPG) 10 shown in fig. 1. The IPG 10 includes a generally electrically conductive biocompatible device housing 12 that houses the circuitry of the IPG and a battery 14 for powering operation of the IPG. The IPG 10 is coupled to the tissue stimulation electrodes 16 by one or more electrode leads forming an electrode array 17. For example, one or more percutaneous leads 15 having a ring or open ring electrode 16 carried on a flexible body 18 may be used. In another example, the paddle leads 19 provide the electrodes 16 positioned on one of their substantially planar surfaces. A lead wire 20 within the lead is coupled to the electrode 16 and to a proximal contact 21 that is insertable into a lead connector 22 that is secured in a head 23 on the IPG 10, which may comprise, for example, epoxy. Once inserted, the proximal contacts 21 connect to header contacts 24 within the lead connector 22, which in turn are coupled through feedthrough pins 25 to stimulation circuitry 28 within the housing 12 through housing feedthroughs 26.

In the illustrated IPG 10, there are 32 electrodes (E1-E32) split between four percutaneous leads 15, or contained on a single paddle lead 19, and thus the header 23 may include a 2 x 2 array of 8-electrode lead connectors 22. However, the type and number of leads and the number of electrodes in an IPG are application specific and may vary accordingly. The conductive housing 12 may also include an electrode (Ec). In SCS applications, one or more electrode leads are typically implanted in the spine near the dura mater, in the spinal cord of the patient, preferably across the left and right of the spinal column of the patient. The proximal contacts 21 penetrate through the patient's tissue to a distal location, such as the buttocks where the IPG housing 12 is implanted, at which point they couple to the lead connector 22. In other IPG examples designed for implantation directly at a site requiring stimulation, the IPG may be leadless, with the electrodes 16 instead appearing on the body of the IPG 10 for contacting the patient's tissue. In other solutions, one or more IPG leads may be integrated with the IPG 10 and permanently connected to the IPG 10. The goal of SCS therapy is to provide electrical stimulation from electrodes 16 to alleviate the patient's symptoms, such as chronic back pain.

The IPG 10 may include an antenna 27a that allows it to communicate bi-directionally with a number of external devices used to program or monitor the IPG, such as a hand-held patient controller or a clinician's programmer as described later with reference to fig. 5. The antenna 27a is shown to comprise a conductive coil within the housing 12, although the coil antenna 27a may also be present in the head 23. When the antenna 27a is configured as a coil, communication with an external device preferably occurs using near field magnetic induction. The IPG 10 may also include a Radio-Frequency (RF) antenna 27 b. In fig. 1, the RF antenna 27b is shown within the head 23, but it could also be within the housing 12. The RF antenna 27b may include patches, slots or wires and may operate as a monopole or dipole. The RF antenna 27b preferably communicates using far-field electromagnetic waves and may operate in accordance with any number of known RF communication standards, such as bluetooth, Zigbee, MICS, and the like.

Stimulation in the IPG 10 is typically provided by pulses, as shown in fig. 2A and 2B. Stimulation parameters typically include the amplitude (A; whether current or voltage) of the pulse; the frequency (F) of the pulses; pulse Width (PW) of the pulse (or its various stages as described below); electrodes 16(E) activated to provide such stimulation; and the polarity (P) of such active electrodes, i.e. whether the active electrode acts as an anode for supplying (source) current to the tissue or as a cathode for drawing (sink) current from the tissue. These and possibly other stimulation parameters employed together constitute a stimulation program that the IPG 10 may execute to provide stimulation to the patient.

The pulses in fig. 2A include two pulse phases 30a and 30b each actively driven by the stimulation circuitry 28 shown in fig. 3. During the first phase 30a, electrode E4 is selected to be the anode and thus provide a positive current of magnitude + A to the tissue, while electrode E5 is selected to be the cathode and thus absorb a corresponding negative current of magnitude-A from the tissue. However, more than one electrode may act as an anode at a given time and more than one electrode may act as a cathode at a given time. Stimulation may also be performed using the housing electrode Ec, as shown in fig. 3.

The pulse shown in fig. 2A with two actively driven phases 30a and 30b is generally referred to as a "biphasic" pulse, where the phases 30a and 30b have opposite polarities. (there may be a short interval period between the two phases 30a and 30b during which no current flows, although this is not shown). The use of biphasic pulses is useful in charge recovery, which may be necessary in view of the capacitance in the current path established between the selected electrodes, as explained further below. Although not shown, each of the stages 30a and 30b may be broken down into a series of higher frequency pulses, commonly referred to as a "train" of pulses, as is well known.

The stimulation circuitry 28 as shown in FIG. 3 includes one or more current source circuits 40_iAnd one or more current sink circuits 42_i. Source 40_iAnd an absorber 42_iMay include a Digital-to-Analog converter (DAC) and may be referred to as the PDAC 40 based on their respective emitted positive (supply, anode) and negative (sink, cathode) currents_iAnd NDAC42_i. In the illustrated example, the NDAC/PDAC 40_i/42_iThe pair is dedicated (hardwired) to a particular electrode node ei 39. For reasons explained below, each electrode node Ei 39 is connected to an electrode Ei 16 via a DC blocking capacitor Ci 38. The stimulation circuitry 28 in this example also supports the selection of the conductive housing 12 as the electrode (Ec 12), which is typically selected for monopolar stimulation. PDAC 40_iAnd NDAC42_iA voltage source may also be included. Although not shown, a switch matrix may be interposed between one or more PDACs 40_iAnd electrode node ei 39, and one or more NDACs 42_iAnd between electrode nodes. The switch matrix allows one or more of the PDACs or one or more of the NDACs to be connected to one or more anode or cathode electrode nodes at a given time.

The stimulation circuitry 28 is configured by stimulation parameters, which may be provided to the stimulation circuitry 28 by controller circuitry 29 in the IPG 10. The controller circuitry 29 may include a microcontroller, microprocessor, microcomputer, FPGA, other digital logic structure, etc., which is capable of executing instructions for the electronic device. The controller circuitry 29 may comprise a separate component or may be Integrated with an Application Specific Integrated Circuit (ASIC) that includes the stimulation circuitry 28 and other circuitry required to operate the various functions of the IPG 10. PDAC 40 pair by stimulation parameters_iAnd NDAC42_iThe appropriate control of which allows any one of the electrodes 16 to act as an anode or cathode to produce a prescribed magnitude of current I through the patient's tissue R, with a desirable therapeutic effect. In the example shown, and during the first stage 30a in which electrodes E4 and E5 are selected as anode and cathode, respectively, PDAC 40₄And NDAC42₅Is activated and digitally programmed (e.g., according to a prescribed frequency F and pulse width PWa) to produce the desired current a with the correct timing. During the second stage 30b (PWb), the PDAC 40₅And NDAC42₄Will be activated to reverse the polarity of the current. More than one anode electrode and more than one cathode electrode may be selected at a time, and thus current may flow through the tissue R between two or more of the electrodes 16. Power for the stimulation circuitry 28 is provided by the compliance voltage VH, as described in further detail in U.S. patent application publication 2013/0289665. Other examples of stimulation circuitry and details of various PDAC and NDAC circuits are disclosed in USP 6,181,969, 8,606,362, 8,620,436, U.S. patent application publications 2018/0071520 and 2019/0083796. Note that stimulation circuitry 28 can be uniqueThe Current at any one of the electrodes is set up on site — this is sometimes referred to as Multiple Independent Current Control (MICC).

A DC blocking capacitor Ci 38 is placed in series between each of the electrode nodes Ei 39 and the electrode Ei 16 (including the case electrode Ec 12). The DC blocking capacitor 38 acts as a safety measure to prevent DC current from being injected into the patient, such as would occur if there were a circuit failure in the stimulation circuitry 28. The DC blocking capacitor 38 is typically provided off-chip (outside of the ASIC or ASICs) and may instead be provided in or on a circuit board in the IPG 10 for integrating its various components, as explained in U.S. patent application publication 2015/0157861.

As described above, the biphasic pulse shown in fig. 2A may be used to restore the charge stored on the capacitance in the current path, particularly the charge stored on the DC blocking capacitor 38. When driving a constant current I during the first phase 30a, the capacitors in the current path (C4 and C5) will store charge at a rate dV/dt I/C and thus build up a voltage across these capacitors (Vc4 and Vc 5). When the polarity of this current is reversed during the second phase 30b, this stored charge is restored and the voltage across the capacitor preferably returns to zero before the next pulse is issued (i.e., before the next phase 30 a). The use of biphasic pulses in this manner is sometimes referred to as "active" charge recovery, because the charge stored during the first phase 30a is recovered by the current actively driven by the stimulation circuitry 28 during the second phase 30 b. It is generally preferred that during active charge recovery phases 30a and 30b be charge balanced, that is, the amount of charge passed during the first phase 30a is equal to the amount of charge passed during the second phase 30 b. This can be achieved by setting the current amplitude and pulse width to equal values during both phases (| + a | -a |;, PWa ═ PWb). However, this is not strictly necessary and charge balancing can also be achieved if the products of amplitude and pulse width are equal for both phases (or more generally if the areas under their curves are equal).

Sheets may also be usedThe phase pulse then uses passive charge recovery (passive charge recovery) to provide the stimulation pulse, as shown in fig. 2B. Such monophasic pulses include only a single active phase 30a, which is actively driven as before. Since this phase 30a will charge the capacitance in the current path as just described, it is also prudent to recover this charge, but this happens passively without the stimulus circuitry 28 (i.e., PDAC and NDAC) driving the active current. Specifically, the passive charge recovery switch 41_iIs provided in the stimulation circuitry 28 (fig. 3). Switch 41_iCoupled between each of the electrode nodes ei 39 and a reference potential. In the depicted example, this reference potential comprises the voltage of the battery 14 (Vbat), although another reference potential may be used. After the first pulse phase 30a has been emitted, these switches 41_iOf which electrode nodes e4 and e5 participate in providing all, or at least 41, of the current during the first phase₄And 41₅) Closed during the passive charge recovery period 30c (fig. 2B). This places the capacitor charged during the first phase in parallel between the reference potential (Vbat) and the tissue R of the patient. As a result, and as shown in fig. 2B, as the capacitor discharges, a current pulse of opposite polarity will flow at each electrode, which will decay exponentially at a rate dependent on the values of capacitance and resistance inherent in the circuitry and tissue R of the IPG. Preferably, the switch 41_iClosed during period 30c for a duration sufficient to effectively restore all of the charge stored on the capacitive element (e.g., capacitor 38) during the first phase 30 a. At the end of the passive charge recovery period, switch 41_iCan be opened again. Passive charge recovery is more fully explained in U.S. patent application publications 2018/0071527 and 2018/0140831.

Note that passive charge recovery may also be used with the biphasic pulse shown in fig. 2A. Thus, the passive charge recovery period 30c may follow the second active drive phase 30 b. Even if the active drive phases 30a and 30b are designed to be charge balanced, non-idealities may result in imperfect charge balance, and thus it may be prudent to provide passive charge recovery during phase 30c to ensure that charge is fully recovered before the next pulse is issued.

Fig. 4 illustrates an external trial stimulation environment that may be used prior to implantation of the IPG 10 in a patient. During external trial stimulation, stimulation may be attempted on the intended implanted patient without reaching the point at which the IPG 10 is to be implanted. Alternatively, a trial electrode array 17' including one or more leads (e.g., one or more percutaneous leads 15 or paddle leads 19) is implanted in patient tissue 32 at a target location 34, such as within the spine as previously described. The proximal ends of the leads of the test electrode array 17' exit the incision 36 and are connected to an External Test Stimulator (ETS) 40. The ETS 40 generally mimics the operation of the IPG 10, and thus may provide stimulation pulses to the patient's tissue as explained above. See, for example, 9,259,574 which discloses a design for ETS. ETS 40 are typically worn externally by the patient for a short period of time (e.g., two weeks), which allows the patient and his clinician to experiment with different stimulation parameters to try and find a stimulation program that alleviates the patient's symptoms (e.g., pain). If the external trial stimulation proved successful, the trial electrode array 17' is removed and the complete IPG 10 and electrode array 17 are implanted as described above; if unsuccessful, the electrode array 17' is simply removed.

Like the IPG 10, the ETS 40 may include one or more antennas to enable bi-directional communication with external devices, as will be further explained with reference to fig. 5. Such antennas may include near field magnetic induction coil antennas 42a and/or far field RF antennas 42b, as previously described. The ETS 40 may also include stimulation circuitry capable of forming stimulation pulses according to a stimulation program, which may be similar or identical to the stimulation circuitry 28 present in the IPG 10. The ETS 40 may also include a battery (not shown) for operating power.

Fig. 5 illustrates various external devices capable of communicating data wirelessly with the IPG 10 and ETS 40, including a patient hand-held external controller 45 and a clinician programmer 50. Both of the devices 45 and 50 may be used to send a stimulation program to the IPG 10 or ETS 40-that is, their stimulation circuitry is programmed to produce pulses having the desired shape and timing described previously. Both devices 45 and 50 may also be used to adjust one or more stimulation parameters of the stimulation program currently being performed by the IPG 10 or ETS 40. The devices 45 and 50 may also receive information, such as various status information, etc., from the IPG 10 or ETS 40.

The external controller 45 may be, for example, as described in U.S. patent application publication 2015/0080982, and may include a dedicated controller configured to work with the IPG 10. The external controller 45 may also comprise a general purpose mobile electronic Device, such as a mobile telephone that has been programmed with a Medical Device Application (MDA), allowing it to operate as a wireless controller for the IPG 10 or ETS 40, as described in U.S. patent Application publication 2015/0231402. The external controller 45 includes a user interface including means for inputting commands (e.g., buttons or icons) and a display 46. The user interface of the external controller 45 enables the patient to adjust the stimulation parameters, although it may have limited functionality compared to the more powerful clinician programmer 50 described later.

The external controller 45 may have one or more antennas capable of communicating with the IPG 10 and ETS 40. For example, the external controller 45 may have a near field magnetic induction coil antenna 47a capable of wirelessly communicating with the coil antenna 27a or 42a in the IPG 10 or ETS 40. The external controller 45 may also have a far field RF antenna 47b that is capable of wirelessly communicating with the RF antenna 27b or 42b in the IPG 10 or ETS 40. The external controller 45 may also have controller circuitry 48, such as a microcontroller, microprocessor, microcomputer, FPGA, other digital logic structure, etc., capable of executing instructions of the electronic device. The controller circuitry 48 may, for example, receive patient adjustments to the stimulation parameters and create a stimulation program to be wirelessly transmitted to the IPG 10 or ETS 40.

The clinician programmer 50 is further described in U.S. patent application publication 2015/0360038 and is only briefly explained herein. The clinician programmer 50 may include a computing device 51, such as a desktop, laptop or notebook computer, tablet, mobile smart phone, Personal Data Assistant (PDA) -type mobile computing device, or the like. In FIG. 5, the computing device 51 is shown as a laptop computer including typical computer user interface means such as a screen 52, mouse, keyboard, speakers, stylus, printer, etc., all of which are not shown for convenience. Also shown in fig. 5 are accessory devices of the clinician programmer 50 that are typically specific to its operation as a stimulation controller (such as a communication "wand" 54 and joystick 58), which may be coupled to suitable ports on the computing device 51, such as a USB port 59.

The antenna in the clinician programmer 50 used to communicate with the IPG 10 or ETS 40 may depend on the type of antenna included in those devices. If the patient's IPG 10 or ETS 40 includes a coil antenna 27a or 42a, the wand 54 may likewise include a coil antenna 56a to establish near field magnetic induction communication over small distances. In this case, the wand 54 may be attached near the patient, such as by placing the wand 54 in a belt or holster that the patient can wear and near the patient's IPG 10 or ETS 40. If the IPG 10 or ETS 40 includes RF antenna 27b or 42b, the wand 54, computing device 51, or both may likewise include RF antenna 56b to establish communication over a greater distance with the IPG 10 or ETS 40. (in this case, the rod 54 may not be necessary). The clinician programmer 50 may also establish communication with other devices and networks, such as the internet, wirelessly or via a wired link provided at an ethernet or network port.

To program the stimulation program or stimulation parameters for the IPG 10 or ETS 40, the clinician interacts with a clinician programmer Graphical User Interface (GUI)64 provided on the display 52 of the computing device 51. As understood by those skilled in the art, the GUI64 may be presented by executing clinician programmer software 66 on the computing device 51, which may be stored in a non-volatile memory 68 of the device. Those skilled in the art will also recognize that execution of the clinician programmer software 66 in the computing device 51 may be facilitated by control circuitry 70 (such as a microprocessor, microcomputer, FPGA, other digital logic structure, etc.) capable of executing programs in the computing device. In addition to executing the clinician programmer software 66 and presenting the GUI64, such control circuitry 70 is also capable of communicating via the antenna 56a or 56b to communicate stimulation parameters selected via the GUI64 to the IPG 10 of the patient.

A portion of the GUI64 is shown in one example of fig. 6. Those skilled in the art will appreciate that the details of the GUI64 will depend on the location of the clinician programmer software 66 in its execution, which may depend on previous GUI selections that the clinician has made. Fig. 6 shows the GUI64 at a point that allows for setting stimulation parameters for the IPG 10 or ETS 40 of a patient. Although the GUI64 is shown operating in the clinician programmer 50, a user interface of the external controller 45 may provide similar functionality.

Shown on the right is an interface in which specific stimulation parameters may be defined for the stimulation program. The values of the stimulation parameters (A; in this example, current, PW, F) that are related to the shape of the waveform are shown in the waveform parameters interface 84, including buttons that the clinician can use to increase or decrease these values. Such that stimulation parameters associated with the electrode 16 (the active electrode and its polarity) are adjustable in the electrode parameter interface 86. Electrode parameters are also visible and can be manipulated in a lead interface 92 that displays the electrode array 17 (or 17') in approximately its proper position relative to each other, for example, on the left and right sides of the spine (only two leads are shown for simplicity). A cursor 94 (or other selection device such as a mouse pointer) may be used to select a particular electrode in the lead interface 92. Buttons in the electrode parameter interface 86 allow the selected electrode (including the housing electrode Ec) to be designated as anode, cathode, or off. The electrode parameter interface 86 also allows the relative intensity of the anode or cathode current of the selected electrode to be specified in percent X. This is particularly useful if more than one electrode acts as an anode or cathode at a given time, as explained in the' 038 publication. According to the example waveforms shown in fig. 2A and 2B, electrode E4 is selected as the only anode that provides current, as shown by lead interface 92, and this electrode receives X ═ 100% of the specified anode current + a. Likewise, electrode E5 has been selected as the only cathode that absorbs current, and this electrode receives a cathodic current-a of X-100%. Also, more than one electrode at a time may be selected to serve as an anode or cathode, where the electrodes share an anode current + A or a cathode current-A. For example, both electrodes E3 and E4 may be selected to act as anodes, with E3 receiving 30% of + a and E4 receiving 70% of + a. The GUI64 may also include other advanced options not shown that allow, for example, setting the duty cycle (on/off time) of the stimulation pulses, setting the rise time at which the stimulation pulses will reach their programmed amplitude (a), specifying the option to use a biphasic waveform and/or passive charge recovery, etc.

Disclosure of Invention

A method for programming a stimulator device including a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient is disclosed. The method can comprise the following steps: programming a stimulator device to provide a repeating sequence of interleaved first and second pulses at least two of the electrode nodes to create a stimulation current through tissue of the patient via the first and second pulses, wherein at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity and a first passive charge recovery pulse of a second polarity opposite the first polarity, the first passive charge recovery pulse being configured to recover charge stored during the first monophasic pulse, and wherein at the first electrode node, each second pulse comprises a second monophasic pulse of the second polarity and a second passive charge recovery pulse of the first polarity, the second passive charge recovery pulse being configured to recover charge stored during the second monophasic pulse.

In one example, the first passive recovery pulse immediately follows a first monophasic pulse of the first pulses at the first electrode node, and wherein the second passive recovery pulse immediately follows a second monophasic pulse of the second pulses at the first electrode node. In one example, the first monophasic pulse has a first amplitude and a first pulse width, and wherein the second monophasic pulse has a second amplitude and a second pulse width. In one example, the first amplitude and the second amplitude comprise constant current amplitudes. In one example, the first and second magnitudes are equal, and wherein the first and second pulse widths are equal. In one example, the first monophasic pulse and the second monophasic pulse are charge balanced at the first electrode node. In one example, the first monophasic pulse and the second monophasic pulse are not charge balanced at the first electrode node. In one example, the stimulator device includes stimulation circuitry including one or more digital-to-analog converters (DACs) configured to actively drive the first monophasic pulse and the second monophasic pulse at the first electrode node. In one example, the stimulation circuitry includes a plurality of passive recovery switches each coupled between one of the electrode nodes and a reference potential, wherein the first and second passive charge recovery pulses are formed by closing a passive recovery switch coupled to the first electrode node. In one example, the one or more DACs are not configured to actively drive the first and second passive charge recovery pulses. In one example, the one or more DACs include one or more Positive DACs (PDACs) configured to provide current and one or more Negative DACs (NDACs) designed to sink current, wherein the first monophasic pulse is actively driven by at least one of the one or more PDACs at the first electrode node, and wherein the second monophasic pulse is actively driven by at least one of the one or more NDACs at the first electrode node. In one example, the second pulse is centered in time relative to the first pulse at the first electrode node. In one example, the first pulse and the second pulse do not overlap at the first electrode. In one example, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity and a third passive charge recovery pulse of the first polarity, the third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity and a fourth passive charge recovery pulse of the second polarity, the fourth passive charge recovery pulse configured to recover charge stored during the fourth monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the stimulator device further includes a housing for housing the stimulation circuitry, wherein the housing is electrically conductive and includes one of the plurality of electrodes, wherein the second electrode node includes an electrode node coupled to the electrically conductive housing. In one example, the interval period during which no stimulation current flows is between (i) the first monophasic pulse and the first passive charge recovery pulse in each first pulse, and (ii) the second monophasic pulse and the second passive charge recovery pulse in each second pulse. In one example, a first pulse is emitted at a first frequency at a first electrode node, and wherein a second pulse is emitted at the first electrode node at the first frequency. In one example, the stimulator device includes at least one implantable lead, wherein at least some of the electrodes are located on the at least one implantable lead. In one example, the first electrode node comprises an electrode node coupled to an electrode located on at least one implantable lead. In one example, each electrode node is coupled to its associated electrode through a DC blocking capacitor. In one example, the stimulator device includes an implantable pulse generator or an external trial stimulator.

Disclosed is a stimulator device, which may include: a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes of patient tissue configured to be contacted; and stimulation circuitry configured by the stimulation parameters to provide a repeating sequence of interleaved first and second pulses at least two of the electrode nodes, thereby creating a stimulation current through tissue of the patient via the first and second pulses, wherein, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity and a first passive charge recovery pulse of a second polarity opposite to the first polarity, the first passive charge recovery pulse being configured to recover charge stored during the first monophasic pulse, and wherein, at the first electrode node, each second pulse includes a second monophasic pulse of a second polarity and a second passive charge recovery pulse of the first polarity, the second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

In one example, the first passive recovery pulse immediately follows a first monophasic pulse of the first pulses at the first electrode node, and wherein the second passive recovery pulse immediately follows a second monophasic pulse of the second pulses at the first electrode node. In one example, the first monophasic pulse has a first amplitude and a first pulse width, and wherein the second monophasic pulse has a second amplitude and a second pulse width. In one example, the first amplitude and the second amplitude comprise constant current amplitudes. In one example, the first and second magnitudes are equal, and wherein the first and second pulse widths are equal. In one example, the first monophasic pulse and the second monophasic pulse are charge balanced at the first electrode node. In one example, the first monophasic pulse and the second monophasic pulse are not charge balanced at the first electrode node. In one example, the stimulation circuitry includes one or more digital-to-analog converters (DACs) configured to actively drive the first monophasic pulse and the second monophasic pulse at the first electrode node. In one example, the stimulation circuitry includes a plurality of passive recovery switches each coupled between one of the electrode nodes and a reference potential, wherein the first and second passive charge recovery pulses are formed by closing a passive recovery switch coupled to the first electrode node. In one example, the one or more DACs are not configured to actively drive the first and second passive charge recovery pulses. In one example, the one or more DACs include one or more Positive DACs (PDACs) configured to provide current and one or more Negative DACs (NDACs) designed to sink current, wherein the first monophasic pulse is actively driven by at least one of the one or more PDACs at the first electrode node, and wherein the second monophasic pulse is actively driven by at least one of the one or more NDACs at the first electrode node. In one example, the second pulse is centered in time relative to the first pulse at the first electrode node. In one example, the first pulse and the second pulse do not overlap at the first electrode. In one example, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity and a third passive charge recovery pulse of the first polarity, the third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity and a fourth passive charge recovery pulse of the second polarity, the fourth passive charge recovery pulse configured to recover charge stored during the fourth monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the stimulator device further includes a housing for housing the stimulation circuitry, wherein the housing is electrically conductive and includes one of the plurality of electrodes, wherein the second electrode node includes an electrode node coupled to the electrically conductive housing. In one example, the interval period during which no stimulation current flows is between (i) the first monophasic pulse and the first passive charge recovery pulse in each first pulse, and (ii) the second monophasic pulse and the second passive charge recovery pulse in each second pulse. In one example, a first pulse is emitted at a first frequency at a first electrode node, and wherein a second pulse is emitted at the first electrode node at the first frequency. In one example, the stimulator device further includes at least one implantable lead, wherein at least some of the electrodes are located on the at least one implantable lead. In one example, the first electrode node comprises an electrode node coupled to an electrode located on at least one implantable lead. In one example, each electrode node is coupled to its associated electrode through a DC blocking capacitor. In one example, the stimulator device includes an implantable pulse generator or an external trial stimulator.

Disclosed is a non-transitory computer readable medium comprising instructions for programming a stimulator device comprising a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient, wherein the instructions, when executed, are configured to perform the method of: programming stimulation circuitry in the stimulator device to provide a repeating sequence of interleaved first and second pulses at least two of the electrode nodes to create a stimulation current through tissue of the patient via the first and second pulses, wherein, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity and a first passive charge recovery pulse of a second polarity opposite to the first polarity, the first passive charge recovery pulse being configured to recover charge stored during the first monophasic pulse, and wherein, at the first electrode node, each second pulse includes a second monophasic pulse of a second polarity and a second passive charge recovery pulse of the first polarity, the second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

In one example, the non-transitory computer readable medium resides in a stimulator device. In one example, the non-transitory computer readable medium resides in an external device for programming the stimulator device. In one example, the first passive recovery pulse immediately follows a first monophasic pulse of the first pulses at the first electrode node, and wherein the second passive recovery pulse immediately follows a second monophasic pulse of the second pulses at the first electrode node. In one example, the first monophasic pulse has a first amplitude and a first pulse width, and wherein the second monophasic pulse has a second amplitude and a second pulse width. In one example, the first amplitude and the second amplitude comprise constant current amplitudes. In one example, the first and second magnitudes are equal, and wherein the first and second pulse widths are equal. In one example, the first monophasic pulse and the second monophasic pulse are charge balanced at the first electrode node. In one example, the first monophasic pulse and the second monophasic pulse are not charge balanced at the first electrode node. In one example, the second pulse is centered in time relative to the first pulse at the first electrode node. In one example, the first pulse and the second pulse do not overlap at the first electrode. In one example, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity and a third passive charge recovery pulse of the first polarity, the third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity and a fourth passive charge recovery pulse of the second polarity, the fourth passive charge recovery pulse configured to recover charge stored during the fourth monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the stimulator device further includes a housing for housing the stimulation circuitry, wherein the housing is electrically conductive and includes one of the plurality of electrodes, wherein the second electrode node includes an electrode node coupled to the electrically conductive housing. In one example, the interval period during which no stimulation current flows is between (i) the first monophasic pulse and the first passive charge recovery pulse in each first pulse, and (ii) the second monophasic pulse and the second passive charge recovery pulse in each second pulse. In one example, a first pulse is emitted at a first frequency at a first electrode node, and wherein a second pulse is emitted at the first electrode node at the first frequency.

A method for programming a stimulator device including a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient is disclosed. The method can comprise the following steps: receiving, at a Graphical User Interface (GUI) on an external device for programming a stimulation device, stimulation parameters for pulses to be produced at least two of the electrode nodes in the stimulation device; automatically deriving a waveform from the stimulation parameters at the external device, wherein the waveform comprises interleaved first and second pulses at the at least two electrode nodes, wherein in the automatically derived waveform, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity, followed by a first passive charge recovery pulse configured to recover charge stored during the first monophasic pulse, and wherein in the automatically derived waveform, at the first electrode node, each second pulse comprises a second monophasic pulse of a second polarity opposite the first polarity, followed by a second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

In one example, the stimulation parameters do not independently specify interleaved first and second pulses. In one example, in the automatically derived waveform, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity, followed by a third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein in the automatically derived waveform, at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity, followed by a fourth passive charge recovery pulse configured to recover charge stored during the second monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the method further includes transmitting the derived waveform to a stimulator device to generate pulses at least two of the electrode nodes. In one example, automatically deriving the waveform from the stimulation parameters occurs when a user selection is received at the GUI.

A system is disclosed that may include: a stimulator device comprising a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient; and an external device for programming the stimulator device, comprising a non-transitory computer readable medium containing a software program, wherein the software program when executed on the external device is configured to: presenting a Graphical User Interface (GUI) on an external device, receiving stimulation parameters at the (GUI) for pulses to be produced at least two of the electrode nodes in the stimulator device, automatically deriving a waveform from the stimulation parameters, wherein the waveform comprises interleaved first and second pulses at least two electrode nodes, wherein in the automatically derived waveform, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity, followed by a first passive charge recovery pulse configured to recover charge stored during the first monophasic pulse, and wherein in the automatically derived waveform, each second pulse includes, at the first electrode node, a second monophasic pulse of a second polarity opposite the first polarity, followed by a second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

In one example, the stimulation parameters do not independently specify interleaved first and second pulses. In one example, in the automatically derived waveform, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity, followed by a third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein in the automatically derived waveform, at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity, followed by a fourth passive charge recovery pulse configured to recover charge stored during the second monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the software program, when executed on the external device, is further configured to transmit the derived waveform to the stimulator device to generate pulses at least two of the electrode nodes. In one example, the GUI includes a user selectable option to automatically derive waveforms from stimulation parameters.

Disclosed is a non-transitory computer readable medium comprising instructions for an external device for programming a stimulator device comprising a plurality of electrode nodes, each electrode node configured to be coupled to one of a plurality of electrodes configured to contact tissue of a patient, wherein the instructions, when executed on the external device, are configured to perform the method of: providing an input at a Graphical User Interface (GUI) on the external device to receive stimulation parameters of pulses to be generated at least two of the electrode nodes in the stimulator device; automatically deriving a waveform from the stimulation parameters at the external device, wherein the waveform comprises interleaved first and second pulses at the at least two electrode nodes, wherein in the automatically derived waveform, at a first electrode node of the at least two electrode nodes, each first pulse comprises a first monophasic pulse of a first polarity, followed by a first passive charge recovery pulse configured to recover charge stored during the first monophasic pulse, and wherein in the automatically derived waveform, at the first electrode node, each second pulse comprises a second monophasic pulse of a second polarity opposite the first polarity, followed by a second passive charge recovery pulse configured to recover charge stored during the second monophasic pulse.

In one example, the stimulation parameters do not independently specify interleaved first and second pulses. In one example, in the automatically derived waveform, at a second electrode node of the at least two electrode nodes, each first pulse comprises a third monophasic pulse of the second polarity, followed by a third passive charge recovery pulse configured to recover charge stored during the third monophasic pulse, wherein in the automatically derived waveform, at the second electrode node, each second pulse comprises a fourth monophasic pulse of the first polarity, followed by a fourth passive charge recovery pulse configured to recover charge stored during the second monophasic pulse. In one example, the first monophasic pulse and the third monophasic pulse are coincident in time, and wherein the second monophasic pulse and the fourth monophasic pulse are coincident in time. In one example, the first passive charge recovery pulse and the third passive charge recovery pulse are temporally coincident, and wherein the second passive charge recovery pulse and the fourth passive charge recovery pulse are temporally coincident. In one example, the instructions, when executed on the external device, further include transmitting the derived waveform to the stimulator device to generate pulses at least two of the electrode nodes. In one example, the instructions, when executed on the external device, further include providing a user-selectable option on the GUI to automatically derive the waveform from the stimulation parameters.

Drawings

Fig. 1 shows an Implantable Pulse Generator (IPG) that can be used for Spinal Cord Stimulation (SCS) according to the prior art.

Fig. 2A and 2B illustrate examples of stimulation pulses that may be generated by an IPG using active charge recovery and passive charge recovery, respectively, according to the prior art.

Fig. 3 shows stimulation circuitry at an IPG for providing stimulation pulses according to the prior art.

Fig. 4 illustrates an External Trial Stimulator (ETS) that may be used to provide stimulation prior to implantation of an IPG, according to the prior art.

Fig. 5 illustrates various external devices capable of communicating with the IPG and ETS and programming the stimuli therein, according to the prior art.

Fig. 6 shows a Graphical User Interface (GUI) of a clinician programmer external device for setting or adjusting stimulation parameters according to the prior art.

Figure 7 illustrates the "best point search" for determining the effective electrode for a patient using a movable super-perception (supra-perception) bipole.

Fig. 8 shows an optimal point search in which a bipole is composed of virtual poles that do not correspond to the positions of electrodes in an electrode array.

Fig. 9 shows data associating lower frequencies with optimal pulse widths that can be used to provide sub-perception (sub-perception) stimulation in an IPG or ETS.

Fig. 10 illustrates an example of a symmetrical biphasic waveform that may preferably be used to provide the lower frequency stimulation of fig. 9.

Fig. 11 shows a first example of a waveform that mimics the function of the biphasic waveform of fig. 10 but employs the use of monophasic pulses followed by passive charge recovery.

Fig. 12 to 15 show other examples of modifications to the waveform of fig. 11.

FIG. 16 illustrates the use of the waveform of FIG. 11 to create a virtual pole.

Fig. 17 shows options on the external device GUI for allowing the clinician to form the pulse as a biphasic pulse (fig. 10), or a monophasic pulse followed by passive charge recovery (fig. 11).

Detailed Description

Although Spinal Cord Stimulation (SCS) therapy is an effective means of alleviating pain in patients, such stimulation can also lead to paresthesia. Paresthesia, sometimes referred to as "super-perception" therapy, is a sensation that may accompany SCS therapy, such as tingling, stinging, heat, cold, and the like. Generally, the effects of paresthesia are mild, or at least not too severe for the patient. Moreover, paresthesia is often a reasonable trade-off for patients whose chronic pain is now controlled by SCS therapy. Some patients even feel paresthesia comfortable and soothing.

Nonetheless, SCS therapy will ideally provide complete pain relief without paresthesia, at least for some patients — this is often referred to as "sub-perception" or sub-threshold therapy that is not felt by the patient. Effective sub-perception therapy can alleviate pain without paresthesia by delivering stimulation pulses at a higher frequency. Unfortunately, such higher frequency stimulation may require more power, which tends to drain the battery 14 of the IPG 10. See, for example, U.S. patent application publication 2016/0367822. If the battery 14 of the IPG is a primary cell and is not rechargeable, high frequency stimulation means that the IPG 10 needs to be replaced more quickly. Alternatively, if the IPG battery 14 is rechargeable, the IPG 10 will need to be charged more frequently, or for a longer period of time. In any event, the patient is inconvenient.

In SCS applications, it is desirable to determine the therapeutic stimulation program that is effective for each patient. An important part of determining an effective therapeutic stimulation program is to determine the "sweet spot" of stimulation in each patient, i.e. to select which electrodes should be active (E) and with what polarity (P) and relative amplitude (X%) to recruit (recurait) and thus treat the nerve site in the patient from which the pain originates. The selection of electrodes near this painful nerve site can be difficult to determine, and experiments are typically conducted to select the best combination of electrodes to provide treatment for the patient. The best point search for determining electrodes for subsequent therapeutic stimulation after the patient has first implanted an electrode array, i.e. after receiving an IPG or ETS, is particularly useful in a trial setting, but the best point search may also be performed at any time during the lifetime of the IPG to optimize the therapy.

As described in U.S. patent application publication 2019/0046800 (' 800 publication), when using sub-perception therapy, selecting electrodes for a given patient may be more difficult because the patient does not feel the stimulation, and thus the patient may have difficulty perceiving whether the stimulation "masks" his pain, and thus whether the selected electrodes are effective. Further, sub-sensory stimulation therapy may require a "wash in" period before it may become effective. The wash period may take one day or more and thus the sub-sensory stimulus may not be immediately effective, making electrode selection more difficult.

The' 800 publication discloses that the sweet spot search can therefore preferably be performed using super-perception stimuli, even if the final stimulation therapy provided after the sweet spot search is sub-perception. By definition, the super-sensory treatment allows the patient to feel the stimulus, which enables the patient to provide substantially immediate feedback to the clinician during the sweet spot search, i.e., whether the paresthesia seems to mask his pain well, without requiring a wash-in period. Further, using super-sensory stimulation during the best point search ensures that the electrodes are determined to be well recruiting the patient's painful nerve sites. As a result, after the sweet spot search is completed and the final sub-perception therapy is provided at the determined electrode, the wash-in of the sub-perception therapy may not take that long because the electrode needed for good recruitment has been reliably determined.

Referring to fig. 7, the sweet spot search described in the' 800 publication is briefly described in a simple example. In this example, it is assumed that the pain site 100 is likely within the tissue region 102. Such regions 102 may be inferred by the clinician based on patient symptoms, for example, by understanding which electrodes are proximate to certain vertebrae (not shown), such as within the T9-T10 gap. In fig. 7, the superaware bipole 104 is selected and applied to the patient at a first location (location 1) in the electrode array 17 or 17'. In this example, the bipolar 104 is initially placed near electrodes E2 and E3, where electrode E2 is selected as the anode that will provide a positive current (+ a) to the patient's tissue, and where electrode E3 is selected as the cathode that will draw a negative current (-a) from the tissue. The particular stimulation parameters selected when forming the bipole 104 may be selected at the GUI64 of the clinician programmer 50 or other external device (such as the patient external controller 45) and wirelessly telemetered to the patient's IPG or ETS for execution. The super-aware dipoles 104 are provided to the patient for a short duration during which the patient provides feedback to the clinician as to how well the dipoles 104 contribute to their symptoms. Such patient feedback may include a pain scale level, which may be entered into the GUI64 of the clinician programmer 50 (or patient controller 45; fig. 5) (as shown in fig. 7), as well as information regarding the current position of the bipole 102 reflected in the anode and cathode electrode positions. The pain Scale Rating may include a Scale from 1 to 10 using a Numerical Rating Scale (NRS) or Visual Analog Scale (VAS), where 1 represents no or little pain and 10 represents the most severe pain that is conceivable. If desired, the GUI64 may include inputs for marking and recording pain levels and bipolar positions.

After testing the bipole 104 in this first position, the bipole 104 can be moved to a different electrode combination, such as anode electrode E3 and cathode electrode E4 (position 2), to again test and record its efficacy. The movement of the dipole may occur in different ways. For example, the GUI may include a dial 112 with arrows that allow the clinician to move both poles up, down, left, and right in the electrode array 17 or 17', which may be engaged using the cursor 94. An accessory device such as joystick 58 (fig. 5) may also be used to move the dipole 104. The user may also enter text into the GUI to set a new position for the dipole. In the example shown, when it is desired to find an electrode combination that covers the pain site 100, one electrode lead of the bipole 104 is moved down and the other electrode lead is moved up, as shown by path 106. In the example of fig. 6, considering that the pain site 100 is close to electrodes E13 and E14, it is expected that the bipole 104 at these electrodes will provide the patient with the best relief, as reflected by the patient's pain score rating. During the sweet spot search, it is not necessary to move the dipole in any particular path 106, but the dipole 104 may move randomly or in other logical ways, perhaps as directed by the patient's input.

The bipole 104 can be formed in different ways and, as described in the' 800 publication, can be formed using a virtual pole 108 (i.e., a virtual anode or cathode) that is not necessarily located at the physical location of the electrode 16. The virtual pole 108 is further discussed in U.S. patent application publication 2018/0243569 (' 569 publication), and thus the virtual pole 108 is only briefly explained herein. If the stimulation circuitry 28 used in the IPG or ETS is capable of independently setting the current at any of the electrodes, a virtual pole is assisted in forming, as explained above with reference to fig. 3.

When using the virtual bipole 104a and as shown in fig. 8, the GUI64 of the clinician programmer 50 (fig. 4) may be used to define the anode (+) and cathode (-)108 at coordinates X, Y in the electrode array 17 or 17'. As explained in the' 569 publication, the electrode configuration algorithm 120 programmed into the control circuitry 70 of the clinician programmer 50 (fig. 5) can calculate from these locations and from other tissue modeling information which physical electrodes 16 will need to be selected, and at what relative magnitudes virtual anodes and virtual cathodes are formed at the specified locations. For example, in fig. 8, the virtual anode is located at a position between the electrodes E2, E3, and E10. The electrode configuration algorithm 120 may then calculate, based on this position, an appropriate fraction (X%) of the total anode current + a that each of the electrodes (during the first pulse phase 30 a) will receive to position the virtual anode at this position. Because the virtual anode is located closest to electrode E2, this electrode E2 may receive the largest share of the specified anode current + a (e.g., 75% + a). Electrodes E3 and E10, which are located close to the virtual anode but farther away, receive a smaller share of the anode current (e.g., 15% x + a and 10% x + a, respectively). Likewise, as can be seen from the designated locations of the virtual cathodes proximate electrodes E4, E11, and E12, these electrodes will receive the appropriate fraction of the designated cathode current a- (e.g., 20% > -a, and 60% > -a, respectively, during the first pulse phase 30 a). These polarities will then be reversed during the second phase 30b of the pulse, as shown by the waveforms of fig. 8. Regardless, the use of virtual poles in the formation of the dipoles 104a allows the field in the tissue to be shaped, and many different electrode combinations may be tried during the optimum point search. In this regard, it is not strictly necessary that the (virtual) bipole moves along the ordered path 106 relative to the electrodes, and the path may be random, possibly as guided by feedback from the patient.

The' 800 publication explains that once the sweet spot search has been completed and the electrodes near the pain site 100 of the patient have been determined, these electrodes (or electrodes near them) may be used to provide sub-perception therapy to the patient. Notably, the' 800 publication discloses that effective sub-perception treatment can occur even at lower frequencies (less than or equal to 10kHz) where lower amounts of power are used in the IPG 10 or ETS 40, and that effectiveness at such lower frequencies is achieved when the pulse width is adjusted to a particular value at each frequency. The graph taken from the' 800 publication is shown in fig. 10, and fig. 10 shows the relationship between this lower frequency and the pulse width that is noted to provide the best sub-perception therapy based on empirical testing. The' 800 publication analyzes this data more deeply, including identifying specific relationships (curve fitting) and frequency/pulse width regions that indicate sub-perceptual significance. The amplitude a of the stimulus provided at such a frequency and pulse width may be titrated down until sub-perception is reached. The reader is assumed to be familiar with the' 800 publication and therefore these details are not repeated here.

Of particular interest in the' 800 publication is the observation that effective super-perception sweet-spot searching and effective sub-perception therapy can be achieved at very low frequencies (less than or equal to 200 Hz). In the' 800 publication, the pulses used during the super-perception optimal point search and/or during sub-perception therapy are preferably symmetrical biphasic pulses. That is, and as shown in fig. 10, the pulse includes at least two active drive phases 30a and 30b, wherein the amplitude a is the same (but of opposite polarity) during each of these phases, and wherein the pulse width PW is also equal. (it is assumed here that a bipolar is formed using the electrodes E13 and E14 near the site of pain 100 in fig. 7). It is postulated that effectiveness is enhanced because each stage 30a and 30b will tend to actively recruit a different neural target in the patient's tissue. That is, a first population of neural targets is recruited during stage 30a, and a second population of (possibly overlapping) neural targets is recruited during stage 30 b. Thus, stimulation coverage is enlarged. In addition, the use of a symmetrical biphasic pulse is beneficial because, as described above, such a pulse is charge balanced and therefore (ideally) restores all stored charge at the end of the second phase 30 b.

However, in some IPGs or ETS, it may be difficult or impossible to form a symmetric biphasic pulse at lower frequencies (e.g., <200 Hz). This is because some IPG/ETS manufacturers may not provide the ability to use dual active drive stages at such low frequencies. Alternatively, the IPG or ETS may only support and the GUI64 of the external device may only allow for the use of monophasic pulses using passive charge recovery, as explained above with reference to fig. 2B. Although it may be possible to "spoof" such devices into a symmetrical biphasic pulse at low frequencies, even if such spoofing is possible, it is inconvenient and difficult to implement. In short, in the inventors 'view, some of the teachings of the' 800 publication may be difficult to implement when using lower frequencies during super-perception sweet spot searching or sub-perception therapy.

To overcome this problem, the inventors disclose the use of new waveforms for use in IPGs or ETS that can effectively create the desired effect of actively driven biphasic pulses at lower frequencies, but through the use of monophasic pulses using passive charge recovery. The waveform includes interleaved first and second pulses at each electrode, such that each electrode emits a first sequence of pulses, followed by a second pulse, followed by a first pulse, and so on. Each first pulse includes a first monophasic pulse of a first polarity having a first amplitude and a first pulse width, and a first passive charge recovery period. The first pulse is preferably emitted at a desired frequency, such as less than 200Hz, which is shown to be useful in, for example, the' 800 publication. Each second pulse includes a second monophasic pulse of a second polarity opposite the first polarity having a second amplitude and a second pulse width, and a second passive charge recovery period. The second pulses are emitted at the same frequency as the first pulses, and each second pulse may be centered in time with respect to the previous and next first pulses at each electrode. Preferably, the first and second amplitudes and the first and second pulse widths are equal, or at least it is desirable that the first and second monophasic pulses of opposite polarity are charge balanced at each electrode. The first monophasic pulse and the second monophasic pulse mimic the function of a biphasic pulse, wherein the first monophasic pulse mimics the function of a first phase of a biphasic pulse, and wherein the second monophasic pulse mimics the function of a second phase of a biphasic pulse. Because each of the first and second pulses comprises a monophasic pulse followed by a passive charge recovery period, they are easily formed at low frequencies in conventional IPG or ETS devices.

Such a waveform is shown in a first example in fig. 11. As just explained, the first pulse 130 is emitted at a frequency F. For example, this frequency F may be less than 200Hz, as shown, for example, to be useful in the' 800 publication, although the disclosed waveforms may be used at any desired frequency. Each first pulse 130 includes a monophasic pulse 132 followed by a passive charge recovery period 134 that generates a passive charge recovery pulse. The passive recovery pulse 134 immediately follows the monophasic pulse 132 of the first pulses at the first electrode node, meaning that it is followed by a minimum interval period, or otherwise meaning that no pulse is emitted between the two, even if the time interval between them is relatively long. Monophasic pulses 132 are actively driven by stimulation circuitry 28 (fig. 3), i.e., by one or more PDACs 40_iOr NDAC42_iDriven depending on whether its polarity is positive or negative. At electrode E13, this monophasic pulse 132 is positive (anodic) with a constant current + a during the pulse width PWa, while at electrode E14, the monophasic pulse is negative (cathodic) with a constant current-a during the pulse width PWa. However, it is not strictly necessary that monophasic pulse 132 remain constant across its pulse width PWa. Alternatively, the amplitude of monophasic pulse 132 may be variable. Further, monophasic pulse 132 may include a voltage rather than a current, which may be positive or variable.

Monophasic pulse 132 at each electrode is followed by a passive charge recovery period 134, which results in a pulse that is not actively driven by stimulation circuitry 28. Alternatively, during the passive charge recovery period 134, the passive charge recovery switch 41 in the stimulation circuitry 28 (fig. 3) is activated_iClosed (i.e., all switches 41) during the passive charge recovery period 134_iOr at least the switch 41₁₃And 41₁₄). Passive charge recovery 134 occurs for a duration PWb. PWb is preferably long enough to allow all stored charge (e.g., + Q at E13, or-Q at E14) to be passively restored (e.g., -Q at E13 or + Q at E14) during period 134 during monophasic pulse 132. The duration PWb of the passive charge recovery period 134 may be variable because of full recoveryThe duration of time required for the complex stored charge will depend on the particular capacitance and resistance involved. Although not shown, a short interval period may separate the monophasic pulse 132 from the passive charge recovery pulse 134 in each first pulse 130.

The second pulses 140 are interleaved with the first pulses 130 at each of the electrodes. The second pulse 140 is preferably identical to the first pulse 130, but of opposite polarity. Thus, the second pulse 140 also includes a monophasic pulse 142 followed by a passive charge recovery period 144. At electrode E13 monophasic pulse 142 is negative (cathodic) having a constant current-A during pulse width PWa, while at electrode E14 monophasic pulse 132 is positive (anodic) having a constant current + A during pulse width PWa. In this example, the monophasic pulses 132 and 142 have the same amplitude (a, although different in polarity) as their pulse width PWa at each electrode, which means that monophasic pulses 132 and 142 are symmetrical and charge balanced at each electrode. However, as described in the examples that follow, this is not strictly necessary. As before, the associated passive charge recovery switch 41 may be closed_iTo implement passive charge recovery period 144, which may again occur over a duration PWb that is again preferably long enough to allow all stored charge during monophasic pulse 142 (e.g., -Q at E13, or + Q at E14) to be passively recovered (e.g., + Q at E13 or-Q at E14) during period 144.

Because the second pulses 140 are interleaved with the first pulses 130 at each electrode, they are also emitted at each electrode at a frequency F. Each second pulse 140 may be completely centered in time with respect to the first pulses 130 that come before and after each electrode. In other words, at each electrode, each second pulse 140 may be issued after the previous first pulse 130 time ta, and may be issued before the next first pulse 140 time tb. (as shown, ta and tb may be measured between the start of monophasic pulses 132 and 142, although other reference points may be selected). As shown in fig. 11, if ta tb, each second pulse 140 may be centered in time, meaning that pulses 130 and 140 are emitted at each electrode at a periodic frequency of 2F. However, it is not strictly necessary that the second pulse 140 be centered in time relative to the first pulses on both sides at each electrode, as discussed subsequently.

When one compares the biphasic waveform of fig. 10 with the waveform of fig. 11, it will be appreciated that the two waveforms should have similar therapeutic effects. As previously described, assuming the waveform of fig. 10 is effective (particularly at lower frequencies, and particularly when sub-perception therapy is applied), because both active drive phases 30a and 30b will tend to actively recruit different neural targets in the patient's tissue, thus expanding stimulation coverage in the patient's tissue. This is also true when pulses 130 and 140 are considered in fig. 11. In essence, the first phase 30a of the active driving of the biphasic pulse of fig. 10 is achieved by the monophasic pulse 132 in the first pulse 130 of fig. 11. Likewise, the second phase 30b of the active drive of the biphasic pulse of fig. 10 is achieved by the monophasic pulse 142 in the second pulse 130 of fig. 11. Moreover, this stimulation in fig. 11 occurs at the same effective frequency F as in fig. 10. In addition, as with the symmetrical biphasic pulse of fig. 10, the waveform of fig. 11 is also charge balanced, and this charge balance can occur in two ways. First, monophasic pulses 132 and 142 may be charge balanced at each electrode. Second, each monophasic pulse 132 and 142 may be charge balanced with its associated passive charge recovery stage 134 and 144. In either case, the waveform of fig. 11 fully restores charge at each electrode within each pulse 130 or 140, or between successive pulses 130 and 140.

In addition, because the waveform at each electrode comprises a monophasic pulse, followed by a passive charge recovery pulse, such a pulse is easily formed in the IPG or ETS, which may not otherwise allow the formation of an actively driven biphasic pulse at the lower frequency F (fig. 10). In this regard, it is noted that IPGs or ETS typically support defining different prescribed pulses in different Timing Channels (TCs). The use of different timing channels allows more complex treatments to be provided by the IPG or ETS, where each timing channel provides its pulses at the same time as the pulses in the other timing channels, even though the pulses in these timing channels do not overlap in time. See, for example, USP 9,656,081 which describes the timing channels in IPGs in more detail). When forming the waveform of fig. 11, note that the first pulse 130 may be defined and formed in a first timing channel (TC1), while the second pulse 140 may be defined and formed in a second timing channel (TC 2). Alternatively, pulses 130 and 140 may be formed in a single timing channel.

Modifications to the waveform of fig. 11 are possible, some of which are shown in fig. 12-16. In fig. 12, the second pulse 140 is not centered in time with respect to the first pulse 130. Alternatively, the second pulse 140 is issued immediately after the end of the first pulse, that is, immediately after the end of the passive charge recovery period 134 of the previous first pulse 130. That is, the second pulse 140 may be emitted at a time ta after the previous first pulse 130. In this case, ta will be shorter than tb (the time to the next first pulse 130), and preferably, ta is at least long enough to encompass the duration of the monophasic pulse 132 (PWa) and the duration of the passive charge recovery period 134 (PWb). Fig. 13 shows a similar modification, except that the second pulse 140 is issued as late as possible before the next first pulse 130 starts. In this example, the second pulse 140 begins with sufficient time to end before a given electrode emits the next first pulse 130. This means that the second pulse starts at least at a time tb before the next first pulse, which means that the time tb is at least as long as the duration of the monophasic pulse 142(PWa) and the passive charge recovery period 144(PWb) of the second pulse 140. In this case, the time tb may be shorter than the time ta, as shown in fig. 13. Of course, the second pulse 140 may occur anywhere between the extremes shown in fig. 12 and 13.

In the modification of fig. 14, the monophasic portions 132 and 142 of the first and second pulses 130 and 140, while having opposite polarities, are not otherwise symmetrical. Specifically, in this example, monophasic pulse 142 in second pulse 140 has a longer duration (PW ') and a lower amplitude (-A') than monophasic pulse 132(PW, + A) in first pulse 130 at electrode E13. Even if asymmetric, monophasic pulses 132 and 142 are still charge balanced at each electrode, i.e., + Q ═ Q |, since PW + a ═ PW' | -a |, in this case. As previously described, in general, charge balancing of pulses 132 and 142 may occur if the areas under each of these curves are equal (although of opposite polarity). The same is true at electrode E14, although the polarity is reversed.

In the modification of fig. 15, monophasic pulses 132 and 142 are not charge balanced at each electrode. Specifically, at electrode E13, monophasic pulse 132 has a charge of + Q, and monophasic pulse 142 has a charge of-Q'. In this example, | Q ' | is less than Q, which may be affected by making the pulse width (PW ') of monophasic pulse 142 less than the Pulse Width (PW) of monophasic pulse 132, or making the amplitude (a ') of 142 less than the amplitude (a) of 132, or both. Even though monophasic pulses 132 and 142 are not charge balanced, each of first and second pulses 130 and 140 is individually charge balanced when considering their passive recovery periods 134 and 144. When monophasic pulse 132 provides a charge of + Q, passive recovery period 134 recovers-Q (assuming that its duration is sufficiently long). Likewise, when monophasic pulse 142 provides a charge of-Q ', passive recovery period 144 recovers + Q' (again assuming that its duration is sufficiently long). Thus, each pulse 130 and 140 is individually charge balanced. Again, the same is true at electrode E14, although the polarity is reversed.

Fig. 16 shows that the waveforms of fig. 11-15 may be provided to more than two electrodes, which as previously described is useful for creating stimulation having virtual poles whose positions may not correspond to the physical positions of the electrodes 16 in the electrode array. Fig. 16 shows this modification applied to the waveforms of fig. 11, but similar modifications may be made to the waveforms of fig. 12-15.

In fig. 16, a dipole 104a having poles 108 is created as previously described (fig. 8). In this example, the anode 108 is virtual and its position does not correspond to the physical position of the electrodes. However, the cathode 108 is positioned at electrode (E14), although this pole 108 may in fact be formed at any random position in the electrode array 17 or 17' by dividing the cathode current-a between the different electrodes. In view of the position of the virtual anode 108 relative to the electrodes E5 and E13, it can be seen that the electrode configuration algorithm 120 explained above has been operated in an associated external device (e.g., clinician programmer 50) to calculate how the anode current + a should be divided between the electrodes to optimally form the virtual anode at the desired location. Specifically, electrode configuration algorithm 120 has calculated that electrode E13 should receive 75% of the anode current + A, while electrode E5 receives the remaining 25%. Note that the use of the electrode configuration algorithm 120 is not strictly necessary. Alternatively, the user may manually choose to use electrodes E13 and E5 as anode electrodes, and may manually choose to split the anode current between them at 75% and 25%, for example using GUI64 of fig. 6.

In any case, the resulting waveform at the electrodes is formed as before, with the first pulse 130 having a monophasic pulse 132 and a passive charge recovery period 134, and the interleaved second pulse 140 having a monophasic pulse 142 and a passive charge recovery period 144. The only difference is the resulting amplitude of the pulse at the activation electrode.

As previously discussed, the use of the described waveforms is considered particularly useful when providing therapeutic sub-sensory stimulation at lower frequencies. However, the use of the disclosed waveforms is not so limited. For example, the disclosed waveforms may be used during a sweet spot search, as discussed above with reference to fig. 7 and 8. In addition, the use of the disclosed waveforms is not limited to sub-perception stimulation or any particular frequency or pulse width. Alternatively, the waveform may be more generally used to provide the oversensing stimulus. Indeed, for the reasons described above, using the disclosed waveforms to provide supra-sensory stimulation may be particularly useful during sweet spot searching. The disclosed waveforms, which simulate the function of an actively driven biphasic waveform (fig. 10), can be used in other stimulation environments where biphasic waveforms are traditionally used.

Fig. 17 illustrates an optional aspect of the GUI64 of the clinician programmer 50 that may be used to form the waveforms of fig. 11-16 with monophasic pulses followed by passive charge recovery. Options have been included that allow the clinician to select the forming of pulses whose stimulation parameters are otherwise specified (e.g., using interfaces 84 and 86) as biphasic pulses (150) (e.g., as shown in fig. 10) or as monophasic pulses (152) (e.g., as shown in fig. 11) using passive charge recovery. If option 150 is selected, the software 66 will acquire the inputted amplitude, pulse width and frequency information, as well as the activated electrodes, their polarities and current fractions (X%) to automatically derive a biphasic waveform with active drive phases 30a and 30b, as explained previously. Once derived, stimulation parameters representing this waveform may be sent from the clinician programmer 50 to the IPG or ETS for execution by the stimulation circuitry. If option 152 most relevant to this is selected, software 66 will take those same parameters and automatically derive waveforms having first and second pulses 130 and 140 of opposite polarity, with each of pulses 130 and 140 having an actively driven monophasic pulse 132 and 142 followed by a passive charge recovery pulse 134 and 144, as explained previously. This is true even though the input stimulation parameters (e.g., a, PW, F) do not themselves independently specify interleaved first and second pulses. The software 66 may derive these waveforms in a single or multiple (e.g., two) timing channels, if necessary, as explained previously. Once derived, stimulation parameters representing this waveform may be sent from the clinician programmer 50 to the IPG or ETS for execution by the stimulation circuitry. Although not shown, the GUI64 may have other options for implementing the modifications previously discussed in fig. 12-16. For example, other options may allow the amplitude and pulse width of monophasic pulses 132 and 142 to be separately tailored (e.g., fig. 14 and 15), or to adjust the relative timing of pulses 130 and 140 (fig. 12 and 13).

Various aspects of the disclosed technology, including programs (such as software program 66) that may be implemented in an IPG or ETS, or in an external device (such as a clinician programmer or external controller), may be formulated and stored as instructions in a computer-readable medium associated with such devices, such as magnetic, optical, or solid-state memory. The computer readable medium having such stored instructions may also include a device readable by a clinician programmer or external controller, such as in a memory stick or removable disk, and may be provided wirelessly to the IPG or ETS. The computer readable medium may reside elsewhere. For example, the computer readable medium may be associated with a server or any other computer device, allowing instructions to be downloaded to a clinician programmer system or external controller or to an IPG or ETS, e.g., over the internet.

Note that some of the applications to which the present disclosure claims priority relate to concepts related to the disclosed waveforms (e.g., selecting optimal stimulation parameters, and particularly stimulation parameters that cause sub-perception at lower frequencies). The techniques in this disclosure may also be used in the context of these priority applications.