Systems and methods with activation recharge stimulation

Abstract

A neural stimulation system may include at least one electrode contact and a neural stimulator configured to deliver stimulation therapy to a patient using an electrical waveform including a first phase of a first polarity and a second phase of a second polarity opposite the first polarity using the at least one electrode contact. The neural stimulator may be configured to therapeutically stimulate nervous tissue using both the first and second phases of the electrical waveform to provide stimulation therapy. The second phase removes accumulated charge caused by the first phase from the at least one electrode contact, and the first phase removes accumulated charge caused by the second phase from the at least one electrode contact. Benefits include reducing energy consumption, using a recharge pulse to activate a population of neuron devices to reduce energy consumption.

Description

[0001] Priority requirements This application claims the benefit of U.S. Provisional Application No. 63 / 527,722, filed July 19, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This document generally relates to medical systems, and more specifically, but not in a limiting way, to systems, devices, and methods for delivering neural stimulation. Background Technology

[0003] Neurostimulation has been proposed as a treatment for a variety of diseases. Generally, neurostimulation and neuromodulation are used interchangeably to describe excitatory stimuli that elicit action potentials, as well as inhibitory and other effects. Examples of neuromodulation include spinal cord stimulation (SCS), deep brain stimulation (DBS), peripheral nerve stimulation (PNS), and functional electrical stimulation (FES).

[0004] Neurostimulation therapy may include an active driving phase (e.g., a stimulation pulse), followed by an active or passive recharge phase to restore the charge injected during the active driving phase. The recharge phase, which restores the charge, addresses potential electrode corrosion and tissue damage. A passive recharge phase may involve setting a switch in the IPG to connect the electrode to a common voltage, effectively short-circuiting the electrode and causing any stored charge in the current path to be balanced by exponential decay through the patient's tissue. An active recharge phase forms part of a biphasic waveform comprising two phases of opposite polarities, both actively driven in opposite directions. The active recharge phase actively restores the charge injected during the first pulse phase. Specifically, when the current is actively driven during the first pulse phase of a biphasic pulse, charge is stored on capacitances in the current path, and when the polarity and therefore direction of the current are reversed during the second phase of the biphasic pulse, the stored charge is actively restored and removed from those capacitances. The interphase interval between the first and second phases of a conventional biphasic pulse is very short (e.g., 100 µs), such that the second phase does not activate the neural element.

[0005] However, because the recharge phase is actively driven in a two-phase pulse, it requires twice the energy compared to an equivalent single-phase pulse with passive recharge. Therefore, some fully implanted devices with limited battery life may not be able to implement two-phase pulses. Summary of the Invention

[0006] By way of example and not limitation, the various embodiments provided herein offer a stimulation pulse paradigm that reduces energy consumption by delivering active recharge pulses in a manner that not only restores charge but also activates neural elements. Thus, as an example, biphasic pulses delivered according to this subject matter would use both phases of the biphasic pulse to stimulate neural elements.

[0007] One example of a system (e.g., Example 1) may include a neurostimulation system comprising at least one electrode contact and a neurostimulator configured to deliver therapeutic stimulation to a patient using the at least one electrode contact using an electrical waveform comprising a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. The neurostimulator may be configured to deliver therapeutic stimulation by using both the first and second phases of the electrical waveform. The second phase removes accumulated charge from the at least one electrode contact caused by the first phase, and the first phase removes accumulated charge from the at least one electrode contact caused by the second phase. The treatment may be provided by a cathode phase and / or an anode phase within the electrical waveform.

[0008] In Example 2, the subject of Example 1 can optionally be configured such that the electrical waveform includes multiple interphase intervals, each of which separates the various phases in the first phase and the various phases in the second phase. The interphase intervals can be longer than the refractory period of the neural tissue. However, if asynchronous activity is intentionally generated in different neural elements, stimulation faster than the refractory period can have the desired effect.

[0009] In Example 3, the subject of Example 2 can optionally be configured such that multiple interphase intervals include an interphase interval of approximately 11 ms to stimulate the target neural tissue at a stimulation frequency of approximately 90 Hz.

[0010] In Example 4, any one or more of the topics in Examples 2-3 can optionally be configured such that the multiple phase intervals include equal intervals.

[0011] In Example 5, any one or more of the topics in Examples 2-4 can optionally be configured such that the multiple phase intervals include different intervals.

[0012] In Example 6, any one or more of the topics in Examples 2-5 can optionally be configured such that each of the plurality of interphase intervals includes at least 1 ms between consecutive phases of the first and second phases.

[0013] In Example 7, any one or more of the subjects in Examples 2-5 may optionally be configured such that the electrical waveform includes a series of therapeutic pulses delivered during a time window, wherein the series of therapeutic pulses includes one or more pulses of a first phase and one or more pulses of a second phase for balancing the net charge on at least one of the first electrode contacts or the second electrode contacts.

[0014] In Example 8, the subject of Example 7 can optionally be configured such that the neurostimulator is also configured to perform additional charge balancing in addition to a series of therapeutic pulses intermittently within a time window according to a predefined charge balancing rule, in order to further balance the net charge.

[0015] In Example 9, the subject of Example 8 can be optionally configured such that the predefined charge balancing rules include rules for performing additional charge balancing at a predefined time, after the delivery of a predefined number of therapeutic pulses, after the delivery of a predefined charge, after the predefined charge per unit time, or based on an estimated instantaneous charge that takes into account slow charge diffusion.

[0016] In Example 10, any one or more of the subjects in Examples 8-9 may optionally be configured such that the neurostimulator is configured to perform additional charge balancing by inserting at least one non-therapeutic pulse within a time window to reduce residual net charge.

[0017] In Example 11, the subject of Example 10 may optionally be configured such that the therapeutic pulse has a first amplitude and a first pulse width, and the non-therapeutic pulse has a second amplitude and a second pulse width, wherein the second amplitude is less than the first amplitude and less than the depolarization threshold for neural tissue, and the second pulse width is greater than the first pulse width.

[0018] In Example 12, the subject of Example 11 can optionally be configured such that the second amplitude is a fraction of the first amplitude (1 / X), the first pulse width is a fraction of the second pulse width (1 / Y) (both X and Y are greater than 1), and Y is greater than X, such that the charge provided by the non-therapeutic pulses is greater than the charge provided by one of the therapeutic pulses. The charge per pulse corresponds to the area under the pulse curve (e.g., the amplitude of a straight wave x the pulse width). The area under the curve for non-therapeutic pulses can be greater than the area under the curve for therapeutic pulses.

[0019] In Example 13, any one or more of the subjects in Examples 8-12 may optionally be configured such that the neural stimulator is configured to perform additional charge balancing by monitoring the net charge and inserting charges to reduce the monitored net charge below a predefined threshold.

[0020] In Example 14, any one or more of the subjects in Examples 1-13 may optionally be configured such that three or more electrode contacts are used to deliver an electrical waveform, with a first phase distributed on at least one of the three or more electrode contacts and a second phase distributed on at least one of the three or more electrode contacts.

[0021] In Example 15, any one or more of the subjects in Examples 1-14 can optionally be configured such that an electrical waveform is delivered via a first timing channel to a first set of electrode contacts including at least one electrode contact. The neurostimulation system can be configured to deliver a second electrical waveform to a second set of electrode contacts via a second timing channel. The second electrical waveform may include a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. At least one shared electrode contact may be present in both the first and second sets of electrode contacts. At least one of the first and second phases of the second electrical waveform removes charge accumulated at at least one shared electrode contact from the first electrical waveform.

[0022] Example 16 includes topics such as methods, devices for performing actions, machine-readable media including instructions that, when executed by a machine, cause the machine to perform actions, or means for execution. This topic can be used to deliver an electrical waveform using at least one electrode contact. The electrical waveform may include a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. Delivering the electrical waveform may include using the first and second phases of the electrical waveform to therapeutically stimulate nerve tissue, using the second phase to reduce the charge buildup from the at least one electrode contact caused by the first phase, and using the first phase to reduce the charge buildup from the at least one electrode contact caused by the second phase.

[0023] In Example 17, the subject of Example 16 may optionally be configured such that the electrical waveform includes a plurality of phase intervals, each of the plurality of phase intervals separating the respective phases in the first phase and the respective phases in the second phase.

[0024] In Example 18, the subject of Example 17 can optionally be configured such that multiple interphase intervals include an interphase interval of approximately 11 ms, to stimulate the target neural tissue with a stimulation frequency of approximately 90 Hz.

[0025] In Example 19, any one or more of the topics in Examples 17-18 can optionally be configured such that the multiple phase intervals include equal intervals.

[0026] In Example 20, any one or more of the topics in Examples 17-19 can optionally be configured such that the multiple phase intervals include different intervals.

[0027] In Example 21, any one or more of the topics in Examples 17-20 may optionally be configured such that each of the plurality of interphase intervals includes at least 1 ms between consecutive phases of the first and second phases.

[0028] In Example 22, any one or more of the subjects in Examples 16-21 may optionally be configured such that the delivery electrical waveform includes delivering a series of therapeutic pulses within a time window by delivering one or more pulses of the first phase and one or more pulses of the second phase within a time window, for balancing the net charge on at least one electrode contact.

[0029] In Example 23, the subject of Example 22 can optionally be configured to further include performing additional charge balancing intermittently in addition to a series of therapeutic pulses, according to predefined charge balancing rules.

[0030] In Example 24, the subject of Example 23 may optionally be configured such that the predefined charge balancing rules include rules for performing additional charge balancing at a predefined time, after delivery of a predefined number of therapeutic pulses, after delivery of a predefined charge, after a predefined charge per unit time, or based on an estimated instantaneous charge taking into account slow charge diffusion.

[0031] In Example 25, any one or more of the subjects in Examples 23-24 may optionally be configured such that additional charge balancing is performed by inserting at least one non-therapeutic pulse within a time window to reduce residual net charge.

[0032] In Example 26, the subject of Example 25 can optionally be configured such that the therapeutic pulse has a first amplitude and a first pulse width, and the non-therapeutic pulse has a second amplitude and a second pulse width. The second amplitude is less than the first amplitude and less than the depolarization threshold for neural tissue, and the second pulse width is greater than the first pulse width.

[0033] In Example 27, the subject of Example 26 can be optionally configured such that the second amplitude is a fraction of the first amplitude (1 / X), the first pulse width is a fraction of the second pulse width (1 / Y) (both X and Y are greater than 1), and Y is greater than X, such that the charge provided by the non-therapeutic pulse is greater than the charge provided by one of the therapeutic pulses.

[0034] In Example 28, any one or more of the topics in Examples 23-27 may optionally be configured such that the neural stimulator is configured to perform additional charge balancing by monitoring the net charge and inserting charges to reduce the monitored net charge below a predefined threshold.

[0035] In Example 29, the subject matter of any one or more of Examples 16-28 may optionally be configured such that the delivery of the electrical waveform includes using three or more electrode contacts, distributing a first phase on at least one of the three or more electrode contacts, and distributing a second phase on at least one of the three or more electrode contacts.

[0036] In Example 30, the subject matter of any one or more of Examples 16-29 may optionally be configured such that delivering an electrical waveform includes delivering a first electrical waveform to a first set of electrode contacts, including at least one electrode contact, via a first timing channel. The subject matter may also include delivering a second electrical waveform to a second set of electrode contacts via a second timing channel. The second electrical waveform may include a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. At least one shared electrode contact is present in both the first and second sets of electrode contacts. At least one of the first and second phases of the second electrical waveform removes charge accumulated at at least one shared electrode contact from the first electrical waveform.

[0037] Example 31 includes a subject matter (such as a non-transitory machine-readable medium including instructions that, when executed by a machine, cause the machine to perform a method for identifying the effective placement of at least one lead having multiple electrodes). The machine-executed method may include delivering an electrical waveform using at least one electrode contact. The electrical waveform may include a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. Delivering the electrical waveform may include using both the first and second phases of the electrical waveform to therapeutically stimulate nerve tissue, using the second phase to reduce the charge buildup from the at least one electrode contact caused by the first phase, and using the first phase to reduce the charge buildup from the at least one electrode contact caused by the second phase. In a further example, the subject matter of Example 32 may be configured such that the machine-executed method may include any of the subject matter described in Examples 17-30.

[0038] In Example 32, the subject of Example 31 may optionally be configured such that the electrical waveform includes a plurality of phase intervals, and each of the plurality of phase intervals separates the respective phases in the first phase and the respective phases in the second phase.

[0039] In Example 33, the subject of Example 32 can optionally be configured such that multiple interphase intervals include an interphase interval of approximately 11 ms, to stimulate the target neural tissue with a stimulation frequency of approximately 90 Hz.

[0040] In Example 34, the subject of Example 31 can optionally be configured such that the method also includes performing additional charge balancing intermittently according to a predefined charge balancing rule.

[0041] In Example 35, the subject of Example 34 may optionally be configured such that therapeutically stimulating neural tissue includes delivering a therapeutic pulse having a first amplitude and a first pulse width, and performing additional charge balancing includes inserting a non-therapeutic pulse having a second amplitude and a second pulse width, the second amplitude being less than the first amplitude and less than a depolarization threshold for neural tissue, and the second pulse width being greater than the first pulse width, and the charge provided by the non-therapeutic pulse being greater than the charge provided by one of the therapeutic pulses.

[0042] This overview is a summary of some of the teachings of this application and is not intended to be exclusive or exhaustive of the subject matter. Further details regarding the subject matter can be found in the detailed description and the appended claims. Other aspects of this disclosure will become apparent to those skilled in the art upon reading and understanding the following detailed description and examining the accompanying drawings, each of which should not be considered limiting. The scope of this disclosure is defined by the appended claims and their legal equivalents. Attached Figure Description

[0043] Various embodiments are shown by way of example in the accompanying drawings. These embodiments are exemplary and are not intended to be exhaustive or exclusive embodiments of the subject matter.

[0044] Figure 1 An embodiment of the neural modulation system is shown by way of example, not limitation.

[0045] Figure 2 It shows that, for example, it can be done Figure 1 An example of a modulation device implemented in a neural modulation system.

[0046] Figure 3 An embodiment of a programming system, such as a programming device, is shown, which can be implemented as follows: Figure 1 Programming devices in neural modulation systems.

[0047] Figure 4 The implantable neural modulation system and a portion of the environment in which the system can be used are illustrated by way of example.

[0048] Figure 5 An example of an SCS system, which may also be referred to as a spinal cord modulation (SCM) system, is shown by way of example.

[0049] Figure 6 Electrical waveforms of a first phase with a first polarity and a second phase with a second polarity opposite to the first polarity are shown by way of example rather than limitation, where both phases are used to therapeutically stimulate nerve tissue while reducing the accumulated charge.

[0050] Figure 7A neurostimulator is shown by way of example, not limitation, which is configured to deliver electrical waveforms from a pulse generator to an electrode contact group via a timing channel.

[0051] Figures 8A-8B The current of the neural stimulation field generated by the first and second phases of the electrical waveform is shown by way of example rather than limitation.

[0052] Figure 9 An electrical waveform with non-uniform biphase pulses is shown by way of example, not limitation, having a uniform phase spacing between the first and second phases, but with non-uniform intervals and non-uniform pulse amplitudes between the biphase pulses.

[0053] Figure 10 An electrical waveform with non-uniform biphase pulses is shown by way of example, not limitation, having a non-uniform phase spacing between the first and second phases, and a non-uniform interval and non-uniform pulse amplitude between the biphase pulses.

[0054] Figure 11 The electrical waveforms delivered to different groups of electrode contacts via multiple timing channels are shown by way of example, not limitation, in a manner that therapeutically stimulates nerve tissue using two phases while reducing the charge buildup.

[0055] Figure 12 Methods for delivering neural stimulation are shown in an illustrative rather than restrictive manner. Detailed Implementation

[0056] The following detailed description of this subject matter takes into account the accompanying drawings, which illustrate specific aspects and embodiments in which the subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the subject matter. Other embodiments may be utilized, and structural, logical, and electrical changes may be made without departing from the scope of the subject matter. References to “a,” “an,” or “various” embodiments in this disclosure do not necessarily refer to the same embodiment, and these references contemplate more than one embodiment. Therefore, the following detailed description should not be considered limiting, and the scope is defined only by the appended claims and the full scope of their legal equivalents.

[0057] This topic provides systems, apparatus, and methods for delivering neural stimulation using electrical waveforms that employ active recharge pulses to not only restore charge but also stimulate neural tissue. Therefore, both phases of a biphasic pulse can be used to deliver neural stimulation, compared to using only the second phase of a biphasic pulse to remove charge, which can reduce the energy consumption of the apparatus used for delivering neural stimulation.

[0058] Figure 1Embodiments of a neural modulation system are illustrated by way of example, not limitation. The illustrated system 100 includes electrode contacts 101 (which may also be simply referred to as electrodes), a modulation device 102, and a programming system (such as programming device 103). The programming system may include multiple devices. The electrode contacts 101 are configured to be placed on or near one or more neural targets of a patient. The modulation device 102 is configured to be electrically connected to the electrode contacts 101 and to deliver neurally modulated energy (such as in the form of electrical pulses) to one or more neural targets via the electrode contacts 101. The delivery of neural modulation is controlled by using multiple modulation parameters. The modulation parameters may specify an electrical waveform (e.g., a pulse or pulse pattern or other waveform shape) and the selection of the electrode contacts through which the electrical waveform is delivered. In various embodiments, at least some of the multiple modulation parameters may be programmable by a user, such as a physician or other caregiver. The programming device 103 provides the user with access to user-programmable parameters. In various embodiments, the programming device 103 is configured to be communicatively coupled to the modulation device via a wired or wireless link. In various embodiments, the programming device 103 includes a graphical user interface (GUI) 104 that allows a user to set and / or adjust the values ​​of user-programmable modulation parameters.

[0059] Figure 2 It shows that, for example, it can be done Figure 1This document describes an embodiment of a modulation device 202 implemented in a neural modulation system 100. The modulation device 202 may also be referred to as a neurostimulator. Various embodiments of neurostimulators can be used to deliver different types of neurotherapy, such as, but not limited to, SCS, DBS, PNS, or FES therapy. The illustrated embodiment of the modulation device 202 includes a modulation output circuit 205 and a modulation control circuit 206. Those skilled in the art will understand that a neural modulation system may include additional components such as sensing circuitry for feedback control of patient monitoring and / or treatment, telemetry circuitry, and a power supply. The modulation output circuit 205 generates and delivers neural modulation. A neural modulation pulse is provided herein as an example. However, the subject matter is not limited to pulses but may include other electrical waveforms (e.g., waveforms with different waveform shapes and waveforms with various pulse patterns). The modulation control circuit 206 uses multiple modulation parameters to control the delivery of the neural modulation pulse. Lead system 207 includes one or more leads and a plurality of electrode contacts 201-1 to 201-N, each lead being configured to be electrically connected to modulation device 202, the plurality of electrode contacts being distributed in an electrode contact arrangement using one or more leads. Each lead may have an electrode contact array consisting of two or more electrode contacts, which may also be referred to as contacts. The plurality of leads can provide a plurality of electrode contact arrays to provide an electrode contact arrangement. Each electrode contact is a single conductive contact providing an electrical interface between modulation output circuit 205 and patient tissue, where N ≥ 2. Neural modulation pulses are each delivered from modulation output circuit 205 through a set of electrode contacts selected from electrode contacts 201-1 to 201-N. For example, the number of leads and the number of electrode contacts on each lead may depend on the distribution of targets for neural modulation and the need to control the distribution of electric field at each target. In one embodiment, by way of example and not limitation, the lead system includes two leads, each with eight electrode contacts. Some embodiments may use a lead system including paddle-shaped leads.

[0060] The actual number and shape of the leads and electrode contacts can vary depending on the intended application. An implantable waveform generator may include a housing for housing electronics and other components. The housing may be composed of a conductive, biocompatible material, such as titanium, forming a sealed compartment where the internal electronics are protected from body tissue and fluids. In some cases, the housing may serve as electrode contacts (e.g., housing electrodes). The waveform generator may include electronic components such as a controller / processor (e.g., a microcontroller), memory, a battery, telemetry circuitry, monitoring circuitry, modulation output circuitry, and other suitable components known to those skilled in the art. The microcontroller executes an appropriate program stored in memory to direct and control the neural modulation performed by the waveform generator. Electrically modulated energy is provided to the electrode contacts according to a set of modulation parameters programmed into the pulse generator. By way of example and not limitation, the electrically modulated energy may be in the form of a pulsed electrical waveform. These modulation parameters may include electrode contact combinations, defining which electrode contacts are activated as anode (positive), cathode (negative), and off (zero), the percentage of modulation energy allocated to each electrode contact (fractionalized electrode contact configuration), and electrical pulse parameters, defining pulse amplitude (measured in milliamperes or volts, depending on whether the pulse generator provides a constant current or a constant voltage to the electrode contact array), pulse width (measured in microseconds), pulse rate (measured in pulses per second), and burst rate (measured in modulation on duration X and modulation off duration Y). Electrode contacts selected for transmitting or receiving electrical energy are referred to herein as "activated," while electrode contacts not selected for transmitting or receiving electrical energy are referred to herein as "inactive."

[0061] Electrical modulation occurs between or among multiple activated electrode contacts, one of which can be the housing of a waveform generator. The system is capable of delivering modulated energy to tissue in a unipolar or multipolar (e.g., bipolar, tripolar, etc.) manner. Unipolar modulation occurs when one of the lead electrode contacts is activated together with the housing of the waveform generator, causing modulated energy to be transferred between the selected electrode contact and the housing. Any of the electrode contacts E1-E16 and the housing electrode contacts can be assigned to up to k possible groups or timing “channels.” In one embodiment, k can be equal to four. The timing channels identify which electrode contacts are selected to synchronously provide or absorb current to create an electric field in the tissue to be stimulated. The amplitude and polarity of the electrode contacts on the channels can vary. Specifically, in any of the k timing channels, the electrode contacts can be selected as positive (anode, source current), negative (cathode, absorb current), or off (no current) polarity. The waveform generator can operate in a mode that delivers electrically modulated energy with a therapeutic effect, causing the patient to perceive the energy delivery (e.g., a therapeutic effect of relieving pain in the presence of perceived sensory abnormalities), and in a sub-sensory mode that delivers electrically modulated energy with a therapeutic effect, but not causing the patient to perceive the energy delivery (e.g., a therapeutic effect of relieving pain in the absence of perceived sensory abnormalities). The waveform generator can also be configured to deliver waveforms or pulses without a therapeutic effect but which can be used for intermittent charge balancing.

[0062] Waveform generators can be configured to individually control the magnitude of the current flowing through each of the electrode contacts. For example, a current generator can be configured to selectively generate individual current-regulated amplitudes from independent current sources for each electrode contact. In some embodiments, the pulse generator can have a voltage-regulated output. While individually programmable electrode contact amplitudes are required for fine control, a single output source that switches across electrode contacts can also be used, although with less fine control in the programming. Neural modulators can be designed using hybrid current and voltage regulation devices.

[0063] A neuromodulation system can be configured to modulate target tissue in the spinal column or other neural tissue. The configuration of electrode contacts used to deliver electrical pulses to the target tissue constitutes an electrode contact configuration, wherein the electrode contacts can be selectively programmed to be anode (positive), cathode (negative), or off (zero). In other words, the electrode contact configuration represents polarity as positive, negative, or zero. The electrode contact configuration can be used to control or modify the electrical waveform used for delivery. The electrical waveform can be an analog or digital signal. In some embodiments, the electrical waveform includes pulses. Pulses can be delivered in a regular, repetitive pattern, or they can be delivered using complex, seemingly irregular pulse patterns. Other parameters that can be controlled or modified include the amplitude, pulse width, and rate (or frequency) of the electrical pulses. Each electrode contact configuration and electrical pulse parameters can be referred to as a “modulation parameter set.” Each set of modulation parameters, including the fractionalized current distribution of the electrode contacts (as a cathode current percentage, anode current percentage, or off), can be stored and combined into a modulation program that can then be used to modulate multiple regions within the patient's body.

[0064] The combination of the number of available electrode contacts and the ability to generate a wide variety of complex electrical waveforms (e.g., pulses) provides clinicians or patients with a vast selection of modulation parameter sets. For example, if a neural modulation system to be programmed has 16 electrode contacts, millions of modulation parameter sets are available for programming into the system. Furthermore, an SCS system, for instance, can have 32 electrode contacts, which exponentially increases the number of modulation parameter sets available for programming. To facilitate this selection, clinicians typically program the modulation parameter sets using computerized programming systems, allowing the optimal modulation parameters to be determined based on patient feedback or other means, and subsequently programming the desired modulation parameter set.

[0065] Figure 3 An embodiment of a programming system, such as programming device 303, is shown, which can be implemented as follows: Figure 1Programming device 103 in a neural modulation system. Programming device 303 includes storage device 308, programming control circuitry 309, and graphical user interface (GUI) 304. Programming control circuitry 309 generates multiple modulation parameters controlling the delivery of neural modulation pulses according to the pattern of the neural modulation pulses. In various embodiments, GUI 304 includes any type of presentation device, such as an interactive or non-interactive screen, and any type of user input device that allows the user to program the modulation parameters, such as a touchscreen, keyboard, keypad, touchpad, trackball, joystick, and mouse. Storage device 308 may store modulation parameters to be programmed into the modulation device. Programming device 303 may send multiple modulation parameters to the modulation device. In some embodiments, programming device 303 may send power to the modulation device. Programming control circuitry 309 may generate multiple modulation parameters. In various embodiments, programming control circuitry 309 may check the values ​​of the multiple modulation parameters against safety rules to limit these values ​​within the constraints of the safety rules.

[0066] In various embodiments, circuitry for neural modulation can be implemented using a combination of hardware, software, and firmware, including the various embodiments discussed herein. For example, GUI circuitry, modulation control circuitry, and programmable control circuitry, including the various embodiments discussed herein, can be implemented using dedicated circuitry configured to perform one or more specific functions or general-purpose circuitry programmed to perform such functions. Such general-purpose circuitry includes, but is not limited to, microprocessors or portions thereof, microcontrollers or portions thereof, and programmable logic circuitry or portions thereof.

[0067] Figure 4An implantable neural modulation system and a portion of the environment in which the system can be used are illustrated by way of example. The system is shown for implantation near the spinal cord. However, the neural modulation system can be configured to modulate other neural targets, including but not limited to SBS, PNS, or FES targets. System 410 includes an implantable system 411, an external system 412, and a telemetry link 413 that provides wireless communication between the implantable system 411 and the external system 412. The implantable system is shown for implantation in a patient. The implantable system 411 includes an implantable modulation device (also referred to as an implantable pulse generator or IPG) 402, a lead system 407, and electrode contacts 401. The lead system 407 includes one or more leads and a plurality of electrode contacts 401 distributed in the one or more leads, each lead being configured to be electrically connected to the modulation device 402. In various embodiments, the external system 412 includes one or more external (non-implantable) devices, each of which allows a user (e.g., a clinician or other caregiver and / or patient) to communicate with the implantable system 411. In some embodiments, the external system 412 includes a programming device designed for initialization and adjustment of settings for the implantable system 411 by a clinician or other caregiver, and a remote control device designed for use by a patient. For example, the remote control device may allow the patient to turn treatment on and off and / or adjust certain patient-programmable parameters among a plurality of modulation parameters. The external system 412 may include personal devices such as telephones and tablets.

[0068] One or more neuromodulation leads of the lead system 407 can be placed near (i.e., resting near) or on the dura mater adjacent to the area of ​​the spinal cord to be stimulated. For example, one or more neuromodulation leads can be implanted along the longitudinal axis of the patient's spinal cord. Due to the lack of space near the location where the neuromodulation leads leave the spine, the implantable modulation device 402 can be implanted in a surgically created pocket in the abdomen or above the buttocks, or it can be implanted in other locations on the patient's body. One or more lead extensions can be used to facilitate implantation of the implantable modulation device 402 away from the exit point of the one or more neuromodulation leads.

[0069] Figure 5An embodiment of an SCS system, also known as a Spinal Cord Modulation (SCM) system, is illustrated by way of example. Similar systems with one or more DBS leads can be used to provide a DBS system. An SCS system 514 typically includes one or more (two illustrated) implantable neural modulation leads 515, an electrical waveform generator 516 such as an implantable pulse generator, an external controller (RC) 517, a clinician's programmer (CP) 518, and an external experimental modulator (ETM) 519. An IPG is used herein as an example of an electrical waveform generator. However, it is particularly noteworthy that the waveform generator can be configured to deliver regular, repetitive pulse patterns, or complex patterns of seemingly irregular pulse patterns, in which the pulses have different amplitudes, pulse widths, pulse intervals, and bursts of different numbers of pulses. It is also particularly noteworthy that the waveform generator can be configured to deliver electrical waveforms other than pulses. Waveform generator 516 may include a pulse generation circuitry system that delivers electrically modulated energy to electrode contacts in the form of a pulsed electrical waveform (i.e., a time sequence of electrical pulses) based on a set of modulation parameters. The electrical waveform may include a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity. Both the first and second phases of the electrical waveform can be used to therapeutically stimulate nerve tissue. The electrical waveform includes a plurality of phase intervals, each of which separates the respective phases in the first and second phases. The second phase can be used to reduce the charge buildup from at least one electrode contact caused by the first phase, and the first phase can be used to reduce the charge buildup from at least one electrode contact caused by the second phase. Waveform generator 516 may be physically connected to a neural modulation lead 515 via one or more percutaneous lead extensions 520, the neural modulation lead 515 carrying a plurality of electrode contacts 521. As shown, the neural modulation lead 515 may be a percutaneous lead, with the electrode contacts arranged in a straight line along the neural modulation lead. Any suitable number of neuromodulation leads can be provided, including only one, as long as the number of electrode contacts is greater than two (including waveform generator housing functions as housing electrode contacts) to allow for lateral current redirection. Alternatively, surgical paddle wires can be used instead of one or more percutaneous leads.

[0070] The ETM 519 can also be physically connected to the neural modulation lead 515 via a percutaneous lead extension 522 and an external cable 523. The ETM 519 may have a waveform generation circuitry similar to that of the waveform generator 516 to deliver electrically modulated energy to the electrode contacts based on a set of modulation parameters. The ETM 519 is a non-implantable device used as a testbed after the neural modulation lead 515 has been implanted and before the waveform generator 516 has been implanted to test the responsiveness of the modulation to be delivered. The functionality described herein with respect to the waveform generator 516 can also be performed with respect to the ETM 519.

[0071] RC 517 can be used for telemetry control of ETM 519 via bidirectional RF communication link 524. RC 517 can also be used for telemetry control of waveform generator 516 via bidirectional RF communication link 525. This control allows waveform generator 516 to be turned on or off and programmed with different sets of modulation parameters. Waveform generator 516 can also be operated to modify the programmed modulation parameters to actively control the characteristics of the electrically modulated energy output by waveform generator 516. Clinicians can use CP 518 to program modulation parameters into waveform generator 516 and ETM 519 in the operating room and during follow-up sessions. Waveform generator 516 can be implantable. Implantable waveform generator 516 and ETM 519 can have features related to... Figure 2 Similar features discussed in the modulation device 202 described.

[0072] CP 518 can communicate indirectly with waveform generator 516 or ETM 519 via RC 517, IR communication link 526, or other links. CP 518 can also communicate directly with waveform generator 516 or ETM 519 via RF communication link or other links (not shown). Detailed modulation parameters provided by CP 518 can also be used to program RC 517 so that the modulation parameters can be subsequently modified by operating RC 517 in stand-alone mode (i.e., without the assistance of CP 518). Various devices can be used as CP 518. Such devices can include portable devices such as laptops, minicomputers, personal digital assistants (PDAs), tablets, mobile phones, or remote controls (RCs) with extended functionality. Therefore, the programming method can be executed by executing software instructions contained in CP 518. Alternatively, this programming method can be executed using firmware or hardware. In any case, CP 518 can actively control the characteristics of the electrical modulation generated by waveform generator 516 to allow the determination of desired parameters based on patient feedback or other feedback, and subsequently program waveform generator 516 with the desired modulation parameters. To allow the user to perform these functions, CP 518 may include user input devices (e.g., a mouse and keyboard) and a programming display screen housed in a housing. In addition to a mouse, or in lieu of a mouse, other directional programming devices may be used, such as a trackball, touchpad, joystick, touchscreen, or directional keys included as part of the keys associated with the keyboard. External devices (e.g., CP) can be programmed to provide a display screen that, among other functions, allows clinicians to select or input patient profile information (e.g., name, date of birth, patient identity, physician, diagnosis, and address), input procedural information (e.g., programming / follow-up, implantation of experimental systems, implantation of waveform generators, implantation of waveform generators and leads, replacement of waveform generators, replacement of waveform generators and leads, replacement or modification of leads, explants, etc.), generate patient pain maps, define lead configuration and orientation, initiate and control the electrically modulated energy output from the neuromodulation leads, and select and program IPG with modulation parameters in surgical and clinical settings.

[0073] The external charger 527 can be a portable device for percutaneous charging of the waveform generator via a wireless link (such as an inductive link 528). Once the waveform generator has been programmed and its power supply has been charged by the external charger or otherwise supplemented, the waveform generator can operate as programmed without the presence of RC or CP.

[0074] Various embodiments of this subject provide an electrical waveform configured to provide a recharge phase of a bipolar stimulation pulse. The bipolar stimulation consists of at least one electrode contact serving as a cathode and at least one electrode contact serving as an anode, which are simultaneously switched on in space and have balanced currents. Typically, neural activation occurs near the cathode, and this cathode neural activation is typically therapeutic. However, it should be noted that the anodic phase can sometimes be therapeutic when the stimulation amplitude is sufficiently high. For example, both phases are considered potentially therapeutic in deep brain stimulation.

[0075] Figure 6 The electrical waveforms of a first phase with a first polarity and a second phase with a second polarity opposite to the first polarity are shown by way of example, not limitation, where both phases are used to therapeutically stimulate nerve tissue while reducing accumulated charge. The figure shows leads 629 having a first electrode contact 630A and a second electrode contact 630B for delivering the electrical waveforms. The waveforms can be represented by a first waveform 631A at the first electrode contact 630A and a second waveform 631B at the second electrode contact 630B. The pulses in the first waveform 630A and the second waveform 630B are opposite because the current flowing from the first electrode contact 630A will return to the second electrode contact 630B, and the current flowing from the second electrode contact 630B will return to the first electrode contact 630A.

[0076] The waveform is shown as alternating pulse phases (e.g., phase 1 and the opposite phase 2), which can be considered together as biphasic pulses (e.g., see biphasic pulse 1 (BP1) and biphasic pulse 2 (BP2)). During each of these two phases, a neural population may be activated. The stimulated neural tissue may be located between the first and second electrode contacts, below either the first or second electrode contact, and / or may be an axon or other long conductive element extending below both the first and second electrode contacts. For example, in cases where the same neural tissue is activated by each of the two phases, the phase interval can be used to control the desired stimulation frequency. In one specific example, a 10 ms phase interval from one pulse phase to another may be used to provide a stimulation frequency of 100 Hz (1 / 10 ms = 100 Hz). In another specific example, an 11 ms phase interval from one pulse phase to another may be used to provide a stimulation frequency of 90 Hz (1 / 11 ms is approximately equal to 90 Hz). The second pulse or recharge pulse may be symmetrical to the first pulse having the opposite polarity. The second pulse can remove the charge density accumulated on both contacts. For example, when delivering waveforms using the first and second electrode contacts, the first pulse can activate a neural population at least near the original cathode, and the second pulse can activate a neural population at least near the original anode.

[0077] Some embodiments may intermittently introduce one or more charge-balancing pulses to ensure no charge accumulation at the electrode contacts due to irreversible redox reactions. For example, some embodiments may incorporate a charge-balancing pulse after each second stimulation pulse. The charge-balancing pulse may “skip” the period of the biphasic pulse waveform and may take any shape, including but not limited to rectangles, attenuation exponents (including phase-to-phase), triangles, and rectified sine curves. The width and amplitude of the charge-balancing pulse may depend on the waveform shape. Charge balance can be determined using the discrete integral or sum of the charge accumulation calculated from the stimulation phase. Charge balance “trimming” may also take into account charge discharge after the initial stimulation phase due to the length of the phase intervals between pulses. Additional charge-balancing pulses may not activate the neural element and may therefore be considered non-therapeutic pulses rather than therapeutic pulses. Additional charge balancing may be performed according to predefined charge-balancing rules. Examples of such rules include, but are not limited to, performing additional charge balancing at a predefined time, after delivering a predetermined number of therapeutic pulses, after delivering a predefined charge, after a predefined charge per unit time, or based on an estimated instantaneous charge considering slow charge diffusion. Non-therapeutic pulses may be delivered to reduce residual net charge. The therapeutic pulse may have a first amplitude and a first pulse width, and the non-therapeutic charge balancing pulse may have a second amplitude and a second pulse width. Typically, the second amplitude may be smaller than the first amplitude and may be smaller than the depolarization threshold for neural tissue. The second pulse width may be greater than the first pulse width. The charge provided by the non-therapeutic pulse may be greater than the charge provided by one of the therapeutic pulses. For example, the charge associated with a linear pulse is the area under the curve, which corresponds to the product of the pulse amplitude and the pulse width. The second amplitude of the non-therapeutic pulse may be a fraction of the first amplitude of the therapeutic pulse (1 / X) (e.g., X is greater than 1). The first pulse width of the therapeutic pulse may be a fraction of the second pulse width of the non-therapeutic pulse (1 / Y) (e.g., Y is greater than 1). That is, the proportion by which the second pulse width is greater than the first pulse width is greater than the proportion by which the first pulse amplitude is greater than the second pulse amplitude, such that the charge provided by the non-therapeutic pulse is greater than the charge provided by one of the therapeutic pulses. As described above, the second amplitude may be smaller than the first amplitude and may be smaller than the depolarization threshold for neural tissue, and the second pulse width may be greater than the first pulse width. However, if the first pulse is cathode and the second pulse is anode, a technically larger anode pulse can be used to achieve charge balancing without activating almost the same amount of underlying neural tissue, and the pulse width of the second pulse can be correspondingly smaller. According to some embodiments, the neurostimulator can be configured to perform additional charge balancing by monitoring the net charge and inserting charges to reduce the monitored net charge below a predefined threshold.

[0078] Figure 6The waveform shown is a relatively simple embodiment in which the first phase and each of these pulse phases have the same pulse amplitude and the same pulse width, and also have the same pulse interval, including the pulse interval between the first phase and the subsequent second phase (phase interval 1-2) and the same pulse interval between the second phase and the subsequent first phase (phase interval 2-1). Furthermore, phase interval 1-2 and phase interval 2-1 can be equal. However, as long as the charge balance is maintained within a certain window and the waveform remains generally non-polarized, the pulses do not need to be the same throughout the waveform.

[0079] Figure 7 A neurostimulator is shown by way of example, not limitation, configured to deliver electrical waveforms from a pulse generator to an electrode contact assembly via a timing channel. Neurostimulator 702 may be... Figure 1 and Figure 2 This is one embodiment of the modulation devices 102 and 202 shown. The neurostimulator 702 includes a pulse generator 732, an arrangement of electrode contacts 733, and at least two channels 734A and 734B through which the pulse generator 732 delivers electrical waveforms to the electrode contact group 733 formed by the arrangement of electrode contacts. The waveform delivered in each timing channel 734A and 734B includes its own set of pulse parameters defining the electrical waveform, including pulse amplitude, pulse width, inter-pulse interval, and polarity, etc. Furthermore, each timing channel is connected to a set of electrode contacts, which may be different from a set of electrode contacts used by other timing channels. Thus, for example, the arrangement of electrode contacts may include a first set of electrode contacts and a second set of electrode contacts. The first and second sets may include one or more identical electrode contacts, and the first and second sets may include one or more different electrode contacts. Furthermore, some electrode contacts in a given group may have the same first polarity, and other electrode contacts in a given group may have the same second polarity opposite to the first polarity.

[0080] Figures 8A-8B The current of the neural stimulation field generated by the first and second phases of the electrical waveform is illustrated by way of example, not limitation. The field extends between electrode contacts of a first subset 835 having a first polarity and electrode contacts of a second subset 836 having a second polarity. For simplicity, each of the first and second subsets includes only one electrode contact, such that electrode contact 1 and electrode contact 2 have opposite polarities. Therefore, in the case of... Figure 8A During the first pulse phase shown, the stimulation field 837 can extend from electrode contact 1, where a positive current is injected into the tissue, to electrode contact 2, where a positive current is returned; and as shown Figure 8BDuring the second pulse phase shown, the stimulation field 837 extends from electrode contact 2 where a positive current is injected into the tissue to electrode contact 1 where a positive current is returned. Those skilled in the art of neurostimulation will understand that negatively charged electrons provide an electronic current in the opposite direction to the positive current. Therefore, the first phase causes electrons to appear at electrode contact 2, and the second phase causes electrons to appear at electrode contact 1. Furthermore, the first phase tends to remove charge (e.g., electrons) accumulated at electrode contact 1, and the second phase tends to remove charge (e.g., electrons) accumulated at electrode contact 2. Typically, neural activation occurs near electrode contacts from which a negative pulse injects an electronic current into the tissue. These electrode contacts act as cathodes during the negative pulse. Negative (cathode) pulses can be used to induce action potentials in nerve tissue and are therefore considered therapeutic pulses. However, anodic stimulation from electrode contacts from which positive pulses originate can also provide therapeutic pulses.

[0081] Figure 9 An electrical waveform with non-uniform biphase pulses is shown by way of example, not limitation, where the non-uniform biphase pulses have a uniform interphase spacing between the first and second phases, but non-uniform intervals and non-uniform pulse amplitudes between the biphase pulses. The figure shows leads 929 with first electrode contacts 930A and second electrode contacts 930B for delivering the electrical waveform. The waveform can be represented by a first waveform 931A at the first electrode contact 930A and a second waveform 931B at the second electrode contact 930B. The pulses in the first waveform 930A and the second waveform 930B are opposite because the current flowing from the first electrode contact 930A returns to the second electrode contact 930B, and the current flowing from the second electrode contact 930B returns to the first electrode contact 933A. Each biphase pulse (e.g., BP1, BP2, BP3, etc.) has a first phase and a second phase of equal magnitude but opposite polarity. Therefore, each biphase pulse is charge-balanced. However, the interphase interval 1-2 from the first phase to the second phase is different for different pulses in a biphase pulse (e.g., BP1, BP2, BP3, etc.). Furthermore, the interphase interval 2-1 from the second phase to the subsequent first phase also varies in the electrical waveform. In cases where the electrical waveform comprises a series of biphase pulses, the interphase interval 2-1 may also be referred to as the interval between biphase pulses or simply the biphase pulse interval, and the interphase interval 1-2 may be referred to as the biphase pulse interval. This figure illustrates that individual cathode and anode pulses do not need to be uniformly spaced. However, pulses can be delivered in a manner that maintains charge balance within a time window. In some embodiments, continuous pulses may be charge-balanced. Additionally or alternatively, some embodiments may include a charge balance “trimming” phase during the interphase time.

[0082] Figure 10An electrical waveform with non-uniform biphase pulses is illustrated by way of example, not limitation, having a non-uniform interphase spacing between the first and second phases, and a non-uniform interval and non-uniform pulse amplitude between the biphase pulses. The figure shows leads 1029 having first electrode contacts 1030A and second electrode contacts 1030B for delivering the electrical waveform. The waveform can be represented by a first waveform 1031A at the first electrode contact 1030A and a second waveform 1031B at the second electrode contact 1030B. The pulses in the first waveform 1030A and the second waveform 1030B are opposite because the current flowing from the first electrode contact 1030A returns to the second electrode contact 1030B, and the current flowing from the second electrode contact 1030B returns to the first electrode contact 1030A. Each of the biphase pulses (e.g., BP1, BP2, BP3, etc.) has a first phase and a second phase of equal magnitude but opposite polarity. Therefore, each biphase pulse is charge-balanced. However, the phase interval 1-2 from the first phase to the second phase is different for different pulses in a biphase pulse (e.g., BP1, BP2, BP3, etc.). Furthermore, the pulse amplitude of one biphase pulse may differ from the pulse amplitude of another biphase pulse. Additionally, the phase interval 2-1 from the second phase to the subsequent first phase also varies in the electrical waveform. In cases where the electrical waveform comprises a series of biphase pulses, the phase interval 2-1 may also be referred to as the interval between biphase pulses or simply the biphase pulse interval, and the phase interval 1-2 may be referred to as the biphase pulse interval. Pulses can be delivered in a manner that maintains charge balance within a time window. Some embodiments may include a charge balance "trimming" phase during the phase-to-phase time.

[0083] Figure 11 The electrical waveforms delivered via multiple timing channels to different groups of electrode contacts are illustrated by way of example, not limitation, in a manner that therapeutically stimulates neural tissue using two phases while reducing accumulated charge. Pulses can be delivered in a spatially distributed manner. That is, different combinations of electrode contacts can be used to deliver pulses. Charge balance can be maintained via trimming phases or by charge balance window rules as described above. For simplicity, amplitudes are shown as identical, and pulses are shown as being delivered simultaneously through two electrode contacts. However, pulses can propagate across three or more electrode contacts in a manner that maintains charge balance rules. Some embodiments may implement rules such that the stimulation phases are always alternating.

[0084] The figure illustrates leads 1129 having first electrode contacts 1130A, second electrode contacts 1130B, third electrode contacts 1130C, and fourth electrode contacts 1130D for delivering electrical waveforms. In the non-limiting example shown, both the first pulse 1138 and the second pulse 1139 utilize electrode contacts E1 and E4 (e.g., timing channel 1). The combination of these two pulses is similar to the biphase pulses shown in the previous example. However, the third pulse 1340 uses electrode contacts E3 and E4 (e.g., timing channel 2), the fourth pulse 1341 uses electrode contacts E2 and E3 (e.g., timing channel 3), the fifth pulse 1342 uses electrode contacts E2 and E4 (e.g., timing channel 4), the sixth pulse 1343 uses electrode contacts E2 and E3 (e.g., timing channel 3), the seventh pulse 1344 uses electrode contacts E1 and E2 (e.g., timing channel 5), the eighth pulse 1345 uses electrode contacts E1 and E4 (e.g., timing channel 1), and the ninth pulse 1346 uses electrode contacts E1 and E3 (e.g., timing channel 6). These pulses from different timing channels can cooperate to remove charge from previous pulses. Each contact can be paired or associated with at least one other electrode contact to deliver a pulse. Continuous pulses of the same polarity can be given in a manner that maintains charge balance within a time window. The inter-pulse interval can be defined to provide the desired stimulation frequency. For example, an inter-pulse interval of approximately 11 ms can be used to deliver a stimulation frequency of approximately 90 Hz. In one example, a frequency range from approximately 85 Hz to 95 Hz can be considered approximately 90 Hz. In another example, a narrower frequency range from approximately 88 Hz to 92 Hz can be considered approximately 90 Hz. In contrast, the standard inter-phase interval for biphasic pulses is 100 µs, which is a hundred times shorter. As an example, and not a limitation, a 90 Hz pulse width can range from 160 µs to 260 µs. Waveforms delivered according to these parameters are considered beneficial for rapidly recruiting larger areas of neural tissue and for providing rapid-acting subsensory therapy using energy-efficient, low-frequency pulses. The waveforms can also produce patterned (and not necessarily regular) activation of the target dorsal column fibers, sufficient to participate in dorsal horn inhibition mechanisms but insufficient to induce sensory abnormalities (e.g., anterograde activation via the dorsal column nuclei). This pattern is frequency-dependent, and simulations show that the pattern generated by a 90 Hz waveform leads to effective inhibition (Gilbert, JE, Titus, N., Zhang, T., Esteller, R., & Grill, WM (2022), Peripheral inhibition mediates pain relief via low-amplitude spinal cord stimulation: modeling and measurement). Eneuro ).

[0085] Since the inter-pulse interval reflects the true stimulation frequency, it is at least 1-2 ms and can last for 1 second or longer. A 1 ms inter-pulse interval corresponds to a signal of approximately 1 kHz, and a 1-second inter-pulse interval corresponds to an interval of approximately 1 Hz. Mandatory charge balance "trimming" can be enforced according to charge balance rules. Examples of charge balance rules include, but are not limited to, rules for performing additional charge balance at a predefined time, after delivering a predefined number of therapeutic pulses, after delivering a predefined charge, after a predefined charge per unit time, or based on an estimated instantaneous charge that takes into account slow charge diffusion. Trimming can restore perfect charge balance or reduce the value below a threshold. For example, the threshold can be derived from the g. Shannon model limit of 30 μC / cm².

[0086] Figure 12 A method for delivering neural stimulation is illustrated by way of example, not limitation. As shown at 1247, the illustrated method may include delivering an electrical waveform comprising a first phase and a second phase. At 1248, a time window may be monitored to maintain charge balance. At 1249, it may be determined whether the end of the window has been reached. If the end has not been reached, the process may return to continue delivering the electrical waveform 1247 and monitoring the window 1248. If the end of the time window has been reached, the method may check the net charge of one or more electrodes 1250. For example, the charge may be sensed using the electrode contacts themselves by sensing extracellular potential. At 1251, it may be determined whether the charge at the electrode contacts is above a threshold. If it is not above the threshold, the process may return to continue delivering the electrical waveform 1247 and monitoring the window 1248. If it is above the threshold, the process may continue generating trimming pulses to further balance the charge 1252. Waveform delivery may continue by returning to 1247.

[0087] The above detailed description includes reference to the accompanying drawings, which form part of the detailed description. The drawings illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as “examples.” These examples may include elements other than those shown or described. However, the inventors also contemplate examples that provide only those elements shown or described. Furthermore, the inventors also contemplate examples using combinations or arrangements of those elements shown or described.

[0088] The methods described herein may be implemented, at least in part, by a machine or computer. Some examples may include a computer-readable or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the examples above. Implementations of this method may include code, such as microcode, assembly language code, or high-level language code. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of such tangible computer-readable media may include, but are not limited to, hard disks, removable disks or tape cartridges, removable optical discs (e.g., optical discs and digital video discs), memory cards or memory sticks, random access memory (RAM), and read-only memory (ROM).

[0089] The above description is intended to illustrate and not limit. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, such as those employed by one of ordinary skill in the art after reading the above description. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A system comprising: A neurostimulation system comprising at least one electrode contact and a neurostimulator configured to deliver stimulation therapy to a patient using the at least one electrode contact using an electrical waveform comprising a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity, wherein the neurostimulator is configured to deliver the stimulation therapy by therapeutically stimulating nerve tissue using both the first phase and the second phase of the electrical waveform, the second phase removing accumulated charge from the at least one electrode contact caused by the first phase, and the first phase removing accumulated charge from the at least one electrode contact caused by the second phase.

2. The system according to claim 1, wherein, The electrical waveform includes multiple phase intervals, each of which separates the phases in the first phase from the phases in the second phase.

3. The system according to claim 2, wherein, The multiple phase intervals include a phase interval of approximately 11 ms, to stimulate the target neural tissue at a stimulation frequency of approximately 90 Hz.

4. The system according to any one of claims 2-3, wherein, The plurality of phase intervals include equal intervals.

5. The system according to any one of claims 2-4, wherein, The multiple phase intervals include different intervals.

6. The system according to any one of claims 2-5, wherein, Each of the plurality of phase intervals includes at least 1 ms between consecutive phases of the first phase and the second phase.

7. The system according to any one of claims 1-6, wherein, The electrical waveform includes a series of therapeutic pulses delivered during a time window, the series of therapeutic pulses including one or more pulses of the first phase and one or more pulses of the second phase, for balancing the net charge on at least one of the first electrode contacts or the second electrode contacts during the time window.

8. The system according to claim 7, wherein, The neurostimulator is also configured to intermittently perform additional charge balancing beyond the series of therapeutic pulses according to a predefined charge balancing rule, in order to further balance the net charge within the time window.

9. The system according to claim 8, wherein, The predefined charge balance rules include rules for performing additional charge balance at a predefined time, after the delivery of a predefined number of therapeutic pulses, after the delivery of a predefined charge, after a predefined charge per unit time, or based on an estimated instantaneous charge that takes into account slow charge diffusion.

10. The system according to any one of claims 8-9, wherein, The neurostimulator is configured to perform additional charge balancing by inserting at least one non-therapeutic pulse within the time window to reduce residual net charge.

11. The system according to claim 10, wherein, The therapeutic pulse has a first amplitude and a first pulse width, and the non-therapeutic pulse has a second amplitude and a second pulse width, wherein the second amplitude is less than the first amplitude and less than the depolarization threshold for the neural tissue, and the second pulse width is greater than the first pulse width.

12. The system according to claim 11, wherein, The second pulse width is greater than the first pulse width by a greater ratio than the first pulse amplitude is greater than the second pulse amplitude by a greater ratio, such that the charge provided by the non-therapeutic pulse is greater than the charge provided by one of the therapeutic pulses.

13. The system according to any one of claims 8-12, wherein, The neurostimulator is configured to perform additional charge balancing by monitoring net charge and inserting charges to reduce the monitored net charge below a predefined threshold.

14. The system according to any one of claims 1-13, wherein, The electrical waveform is delivered using three or more electrode contacts, wherein the first phase is distributed on at least one of the three or more electrode contacts, and the second phase is distributed on at least one of the three or more electrode contacts.

15. The system according to any one or more of claims 1-14, wherein, The electrical waveform is a first waveform delivered to a first group of electrode contacts including the at least one electrode contact via a first timing channel, and the neurostimulation system is configured to deliver a second electrical waveform to a second group of electrode contacts via a second timing channel, wherein the second waveform includes a first phase of a first polarity and a second phase of a second polarity opposite to the first polarity, and wherein at least one shared electrode contact is present in both the first group of electrode contacts and the second group of electrode contacts, wherein at least one of the first phase and the second phase of the second electrical waveform removes the charge accumulated at the at least one shared electrode contact from the first electrical waveform.

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