Determining a posture state from ecap

Abstract

Systems, devices, and techniques for determining a posture state of a patient based on a detected evoked compound action potential (ECAP) are described. In one example, a medical device includes stimulation circuitry configured to deliver electrical stimulation and sensing circuitry configured to sense a plurality of evoked compound action potential (ECAP) signals. The medical device also includes processing circuitry configured to control the stimulation circuitry to deliver a plurality of electrical stimulation pulses having different amplitude values, control the sensing circuitry to detect a respective ECAP signal of the plurality of ECAP signals after delivery of each electrical stimulation pulse of the plurality of electrical stimulation pulses, and determine a posture state of the patient based on the plurality of ECAP signals.

Description

Technical Field

[0001] This disclosure generally relates to electrical stimulation, and more specifically to the use of electrical stimulation to characterize a patient. Background Technology

[0002] Medical devices can be external or implanted and can be used to deliver electrical stimulation therapy to a patient via various tissue sites to treat a variety of symptoms or conditions, such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. Medical devices can deliver electrical stimulation therapy via one or more leads, which include electrodes located near target sites associated with the patient's brain, spinal cord, pelvic nerves, peripheral nerves, or gastrointestinal tract. Stimulation near the spinal cord, near the sacral nerves, within the brain, and near peripheral nerves are commonly referred to as spinal cord stimulation (SCS), sacral nerve modulation (SNM), deep brain stimulation (DBS), and peripheral nerve stimulation (PNS), respectively.

[0003] Electrical stimulation can be delivered to a patient by a medical device in the form of a train of electrical pulses, and the parameters of the pulses can include frequency, amplitude, pulse width, and pulse shape. Evoked compound action potentials (ECAPs) are synchronous firings of a population of neurons in response to stimulation applied by a medical device (in some cases, electrical stimulation). ECAPs can be detectable because they are events separate from the stimulation itself, and they can reveal the characteristics of the stimulus's effect on nerve fibers. Summary of the Invention

[0004] Generally, systems, devices, and techniques for determining a patient's postural state based on one or more evoked compound action potential (ECAP) signals sensed from the patient are described. The distance between the implanted electrode and the target nerve changes as the patient moves. For example, when the subject is in a supine position, the electrode implanted along the spine is closer to the spinal cord compared to a standing position. Similarly, when the subject coughs or sneezes, the implanted electrode can move closer to the spinal cord. Therefore, the characteristics of the ECAP signal change depending on the stimulus pulse that evokes the ECAP signal and the distance between the electrode and the nerve.

[0005] The devices and systems described herein can determine a subject's current postural state by utilizing the relationship between stimulation pulse parameters and characteristics of the ECAP signal. For example, an implantable medical device (IMD) can deliver multiple stimulation pulses with different stimulation parameter values ​​and detect the resulting ECAP signal from each pulse. The IMD can then determine the relationship between the stimulation parameter values ​​and one or more characteristics of the resulting ECAP signal and identify the subject's postural state. In some examples, the IMD can transmit the identified postural state to an external device for display to a user. In some examples, the IMD can use the identified postural state as feedback to control the delivery of treatment to the subject. For example, the IMD can select stimulation parameter values ​​for electrical stimulation based on the identified postural state or modulate the stimulation parameter values ​​by selecting a target ECAP value for the identified postural state.

[0006] In one example, a system includes: a stimulation circuit system configured to deliver electrical stimulation; a sensing circuit system configured to sense a plurality of evoked compound action potential (ECAP) signals; and a processing circuit system configured to: control the stimulation circuit system to deliver a plurality of electrical stimulation pulses with different amplitude values, control the sensing circuit system to detect a corresponding ECAP signal among the plurality of ECAP signals after each of the plurality of electrical stimulation pulses is delivered, and determine the patient's postural state based on the plurality of ECAP signals.

[0007] In another example, a method includes: a processing circuit system controlling a stimulation circuit system to deliver multiple electrical stimulation pulses with different amplitude values; a processing circuit system controlling a sensing circuit system to detect a corresponding ECAP signal among multiple evoked compound action potential (ECAP) signals after each of the multiple electrical stimulation pulses is delivered; and the processing circuit system determining the patient's postural state based on the multiple ECAP signals.

[0008] In another example, a computer-readable medium includes instructions that, when executed, cause a processing circuitry system to: control a stimulation circuitry system to deliver a plurality of electrical stimulation pulses with different amplitude values; control a sensing circuitry system to detect a corresponding ECAP signal among a plurality of evoked compound action potential (ECAP) signals after each of the plurality of electrical stimulation pulses has been delivered; and determine the patient’s postural state based on the plurality of ECAP signals.

[0009] The summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, apparatus, and methods described in detail in the accompanying drawings and the following detailed description. Further details of one or more examples of this disclosure are set forth in the accompanying drawings and the following detailed description. Other features, objectives, and advantages will be apparent from the specification, drawings, and claims. Attached Figure Description

[0010] Figure 1 This is a conceptual diagram illustrating an exemplary system according to one or more technologies of this disclosure, the exemplary system including an implantable medical device (IMD) configured to deliver spinal cord stimulation (SCS) therapy and an external programmer.

[0011] Figure 2 This is a block diagram illustrating an exemplary configuration of components of an implantable medical device (IMD) according to one or more technologies of this disclosure.

[0012] Figure 3 This is a block diagram illustrating an exemplary configuration of components of an exemplary external programmer according to one or more technologies disclosed herein.

[0013] Figure 4 It is an exemplary evoked compound action potential (ECAP) curve for sensing a corresponding stimulus pulse according to one or more techniques of this disclosure.

[0014] Figure 5 This is a timing diagram illustrating an example of an electrical stimulation pulse and a corresponding sensed ECAP according to one or more techniques of this disclosure.

[0015] Figure 6 It is an exemplary growth curve graph showing the relationship between ECAP amplitude and pulse amplitude under different posture states.

[0016] Figure 7 This is a flowchart illustrating an exemplary technique for determining a patient’s postural state and controlling treatment based on that postural state, according to one or more techniques disclosed herein.

[0017] Figure 8 This is a diagram illustrating an exemplary technique for adjusting stimulation therapy. Detailed Implementation

[0018] This disclosure describes examples of medical devices, systems, and techniques for determining a subject's postural state based on one or more characteristics of evoked compound action potentials (ECAPs). Electrical stimulation therapy is typically delivered to a patient's target tissue (e.g., nerves in the spinal cord or muscles) via two or more electrodes. Parameters of the electrical stimulation therapy (e.g., electrode combination, voltage or current amplitude, pulse width, pulse frequency, etc.) are selected by the clinician and / or patient to provide relief for a variety of symptoms (such as pain, neurological disorders, muscle disorders, etc.). However, the distance between the electrodes and the target tissue changes as the patient moves. Since neural recruitment at the nerve is a function of stimulation intensity (e.g., amplitude and / or pulse frequency) and the distance between the target tissue and the electrode, moving the electrode closer to the target tissue can result in increased neural recruitment (e.g., possible pain sensation or impaired motor function), while moving the electrode further away from the target tissue can result in decreased therapeutic efficacy for the patient. Certain patient postures (which may or may not include patient movement) can represent a corresponding distance (or change in distance) between the electrode and the nerve, and are therefore informative feedback variables for modulating stimulation therapy.

[0019] ECAP is a measure of neural recruitment because each ECAP signal represents a superposition of potentials generated from a set of axons in response to electrical stimulation (e.g., a stimulation pulse). Changes in the characteristics of the ECAP signal (e.g., the amplitude of a portion of the signal or the area under the curve of the signal) occur as a function of the number of axons that have been activated by the delivered stimulation pulse. For a given set of parameter values ​​defining the stimulation pulse and a given distance between the electrode and the target nerve, the detected ECAP signal may have a certain characteristic value (e.g., amplitude). Therefore, the system can determine whether the distance between the electrode and the nerve has increased or decreased in response to determining whether the measured ECAP characteristic value has increased or decreased. For example, if a set of parameter values ​​remains the same and the ECAP characteristic value of the amplitude increases, the system can determine that the distance between the electrode and the nerve has decreased.

[0020] In some examples, effective stimulation therapy may rely on neural recruitment at a certain level at the target nerve. This effective stimulation therapy can provide relief from one or more symptoms (e.g., pain perceived by the patient) without unacceptable levels of side effects (e.g., hypersensitivity to the stimulus). However, if the patient changes posture or otherwise engages in physical activity, the distance between the electrode and the nerve also changes. If the parameter values ​​defining the stimulation pulse are not adjusted to compensate for the distance change, this distance change may result in a loss of effective therapy and / or side effects. The system can modify the stimulation parameters to compensate for changes in the distance between the electrode and the target nerve, such as increasing the stimulation intensity in response to an increase in distance and decreasing the stimulation intensity in response to a decrease in distance. However, the magnitude of any change in the stimulation parameter values ​​may be affected by the patient's postural state. Therefore, if the patient's actual postural state is known and the parameter values ​​corresponding to that postural state are selected, the system can perform more accurate modifications to the stimulation parameter values.

[0021] As described herein, systems, devices, and techniques for determining a patient's postural state based on one or more evoked compound action potential (ECAP) signals sensed from the patient are described. As discussed above, the distance between the implanted electrode and the target nerve changes when the patient moves. For example, when the subject is in a supine position, the electrode implanted along the spine moves closer to the spinal cord than when the subject is in a standing position, the electrode moves closer to the spinal cord. Similarly, the implanted electrode can move closer to the spinal cord during transient events such as when the subject coughs, laughs, or sneezes. Therefore, the characteristic values ​​of the ECAP signal change depending on the stimulus pulse that evoked the ECAP signal and the distance between the electrode and the nerve.

[0022] The system can determine a subject's current postural state by utilizing the relationship between stimulation pulse parameters and characteristics of the ECAP signal. For example, an implantable medical device (IMD) can deliver multiple stimulation pulses with different stimulation parameter values ​​and detect the resulting ECAP signal from each corresponding pulse. Based on the detected ECAP signal, the IMD can determine a relationship between the stimulation parameter value and one or more characteristics of the resulting ECAP signal to identify the subject's postural state. In one example, the relationship could be the amplitude value of the ECAP signal relative to the amplitude of the corresponding pulse that evoked each ECAP signal. A steeper curve between values ​​can represent a positional state with a closer distance between the electrode and the target nerve (e.g., supine position) compared to a shallower curve between values ​​for postural states (e.g., prone position) where the distance between the electrode and the target nerve is greater.

[0023] In some examples, the IMD may use identified postural states as feedback to control the delivery of treatment to the subject. For example, the IMD may select stimulation parameter values ​​for electrical stimulation based on the identified postural state or modulate stimulation parameter values ​​by selecting a target ECAP value for the identified postural state. In some examples, the IMD may select a growth curve corresponding to the identified postural state and adjust the stimulation parameter values ​​of subsequent stimulation pulses according to the selected growth curve. Additionally or alternatively, the IMD may transmit the identified postural state to an external device for display to the user (e.g., via an external programmer). In some examples, the IMD or other device may store the identified postural states and / or use identified postural states detected over time to perform patient monitoring activities.

[0024] In some examples, the ECAP detected by the IMD can be an ECAP induced by a stimulation pulse designed to facilitate treatment of the patient or by a separate pulse configured to elicit an ECAP detectable by the IMD. After the delivered stimulation pulse first depolarizes the nerve, the nerve pulse, detectable as an ECAP signal, travels rapidly along the nerve fiber. If the stimulation pulse delivered by the first electrode has an excessively long pulse width, the different electrodes configured to sense the ECAP will sense the stimulation pulse itself as an artifact that blurs the lower amplitude ECAP signal. However, the ECAP signal loses fidelity as the potential propagates from the electrical stimulation because different nerve fibers propagate the potential at different speeds. Therefore, sensing the ECAP at a location away from the stimulation electrode can avoid artifacts caused by stimulation pulses with long pulse widths, but the ECAP signal may lose the fidelity required to detect changes in the ECAP signal that occur as the distance from the electrode to the target tissue changes. In other words, the system may not be able to identify an ECAP from a stimulation pulse configured to provide treatment to the patient at any distance from the stimulation electrode.

[0025] In some examples, ECAP can be detected from pulses intended to facilitate treatment of the patient. However, when these therapeutic pulses cause artifacts that interfere with the IMD's ability to detect ECAP, the IMD can be configured to deliver pulses separate from those intended to facilitate treatment, in order to achieve the purpose of detecting ECAP without interference from the pulses themselves. Pulses configured to trigger detectable ECAP may be called control pulses, and pulses from which ECAP is not detectable but are otherwise adjusted according to the ECAP signal may be called notification pulses. In this way, multiple control pulses may or may not facilitate treatment received by the patient, and notification pulses are generally configured to facilitate treatment received by the patient. Therefore, the IMD or other components associated with the medical device may alternatively determine the values ​​of one or more stimulation parameters that at least partially define the notification pulse based on the ECAP signal triggered by the control pulse. For example, the control pulse may be configured to trigger an ECAP for detecting the patient's postural state. In this way, the notification pulse can be notified by the ECAP triggered from the control pulse. The medical device or other components associated with the medical device may determine the values ​​of one or more stimulation parameters that at least partially define the control pulse based on the ECAP signal triggered by a previous control pulse.

[0026] Although electrical stimulation is typically described herein as an electrical stimulation pulse, it can be delivered in a non-pulsed form in other examples. For instance, electrical stimulation can be delivered as a signal with various waveform shapes, frequencies, and amplitudes. Thus, electrical stimulation in the form of a non-pulsed signal can be a continuous signal, which may have a sinusoidal waveform or other continuous waveforms.

[0027] Figure 1 This is a conceptual diagram illustrating an exemplary system 100 according to one or more technologies of this disclosure, the exemplary system including an implantable medical device (IMD) 110 configured to deliver spinal cord stimulation (SCS) therapy and an external programmer 150. While the technologies described in this disclosure are generally applicable to a variety of medical devices, including external devices and IMDs, for illustrative purposes, the application of such technologies to IMDs, and more specifically, to implantable electrical stimulators (e.g., neurostimulators), will be described. More specifically, for illustrative purposes, this disclosure relates to implantable SCS systems, but is not limited thereto, and also to other types of medical devices or other therapeutic applications of medical devices.

[0028] like Figure 1 As shown, system 100 includes IMD 110, leads 130A and 130B, and an external programmer 150, which is illustrated in conjunction with patient 105, typically a human patient. Figure 1In this example, IMD 110 is an implantable electrical stimulator configured to generate and deliver electrical stimulation therapy to patient 105 via one or more electrodes of leads 130A and / or 130B (collectively, "leads 130"), for example, to relieve chronic pain or other symptoms. In other examples, IMD 110 may be coupled to a single lead carrying multiple electrodes, or more than two leads each carrying multiple electrodes. In some examples, the stimulation signal or pulse may be configured to trigger a detectable ECAP signal, which IMD 110 may be used to determine the postural state of patient 105 and / or to determine how to adjust one or more parameters defining the stimulation therapy. IMD 110 may be a long-term electrical stimulator that remains implanted in patient 105 for weeks, months, or even years. In other examples, IMD 110 may be a temporary or experimental stimulator used to screen or evaluate the efficacy of electrical stimulation for long-term treatment. In one example, IMD 110 is implanted in patient 105, while in another example, IMD 110 is an external device coupled to a percutaneously implanted lead. In some examples, IMD 110 uses one or more leads, while in other examples, IMD 110 is leadless.

[0029] IMD 110 can be made of components sufficient to mount IMD 110 (e.g., Figure 2 The component shown may be constructed from any polymer, metal, or composite material housed within the patient 105. In this example, the IMD 110 may be constructed with a biocompatible shell, such as titanium or stainless steel, or a polymeric material (such as silicone, polyurethane, or liquid crystal polymer), and surgically implanted into a site near the pelvis, abdomen, or buttocks of the patient 105. In other examples, the IMD 110 may be implanted in other suitable sites within the patient 105, depending on, for example, the target site within the patient 105 for delivering electrical stimulation therapy. The outer shell of the IMD 110 may be constructed to provide a hermetically sealed component, such as a rechargeable or non-rechargeable power source. Furthermore, in some examples, the outer shell of the IMD 110 is selected from materials that facilitate the reception of energy to charge a rechargeable power source.

[0030] The electrical stimulation energy can be, for example, pulses based on a constant current or constant voltage, delivered from the IMD 110 to one or more target tissue sites in the patient 105 via one or more electrodes (not shown) of the implanted lead 130. Figure 1In this example, lead 130 carries electrodes disposed adjacent to the target tissue of spinal cord 120. One or more electrodes may be positioned at the distal end of lead 130 and / or at other locations along the midpoint of lead 130. Lead 130 may be implanted and coupled to IMD 110. The electrodes may transfer electrical stimulation generated by an electrical stimulator in IMD 110 to the tissue of patient 105. Although lead 130 may each be a single lead, lead 130 may include lead extensions or other segments that may facilitate implantation or positioning of lead 130. In some other examples, IMD 110 may be a leadless stimulator having one or more electrode arrays disposed on the housing of the stimulator, rather than leads extending from the housing. Furthermore, in some other examples, system 100 may include one or more leads, each coupled to IMD 110 and pointing to similar or different target tissue sites.

[0031] The electrodes of lead 130 may be electrode pads on a paddle-shaped lead, circular (e.g., annular) electrodes surrounding the lead body, conformal electrodes, cuff electrodes, segmented electrodes (e.g., electrodes disposed at different circumferential positions around the lead, rather than continuous annular electrodes), any combination thereof (e.g., annular electrodes and segmented electrodes), or any other type of electrode capable of forming a combination of monopolar, bipolar, or multipolar electrodes for treatment. For illustrative purposes, annular electrodes disposed at different axial positions at the distal end of lead 130 will be described.

[0032] The deployment of electrodes via lead 130 has been described for illustrative purposes, but electrode arrays can be deployed in different ways. For example, a housing associated with a leadless stimulator can hold electrode arrays, such as rows and / or columns (or other patterns), to which displacement operations can be applied. Such electrodes can be arranged as surface electrodes, ring electrodes, or protrusions. Alternatively, the electrode array can be formed by rows and / or columns of electrodes on one or more paddle-shaped leads. In some examples, the electrode array includes electrode segments arranged at corresponding locations around the periphery of the leads, for example, arranged as one or more segmented rings around the circumference of a cylindrical lead. In other examples, one or more leads in lead 130 are linear leads having eight ring electrodes along the axial length of the lead. In yet another example, the electrodes are segmented rings arranged linearly along the axial length of the lead around the periphery of the lead.

[0033] The set of stimulation parameters for a therapeutic stimulation program that defines the stimulation pulses delivered by the IMD 110 via electrodes of lead 130 for electrical stimulation therapy may include information identifying which electrodes have been selected to deliver stimulation according to the stimulation program, the polarity of the selected electrodes (i.e., the electrode combination used in the program), the voltage or current amplitude of the stimulation delivered by the electrodes, the pulse frequency, the pulse width, and the pulse shape. These stimulation parameter values ​​constituting the set of stimulation parameters defining the pulses may be predetermined parameter values ​​defined by the user and / or automatically determined by the system 100 based on one or more factors or user input.

[0034] If a detectable ECAP signal is required to be triggered by control pulses separate from the notification pulses used for treatment, system 100 may employ an ECAP test stimulation program that defines stimulation parameter values ​​for control pulses delivered by IMD 110 through at least some of the electrodes of lead 130. These stimulation parameter values ​​may include information identifying which electrodes have been selected to deliver the control pulses, the polarity of the selected electrodes (i.e., the electrode combination used in the program), and the voltage or current amplitude, pulse frequency, pulse width, and pulse shape of the stimulation delivered by the electrodes. The stimulation signal (e.g., one or more stimulation pulses or a continuous stimulation waveform) defined by the parameters of each ECAP test stimulation program is configured to evoke a compound action potential from the nerve. In some examples, the ECAP test stimulation program defines when to deliver the control pulse to the patient based on the frequency and / or pulse width of the notification pulse. However, the stimulation defined by each ECAP test stimulation program is not intended to provide treatment to the patient or contribute to the patient's treatment. Additionally, the ECAP test stimulation program may define control pulses for each pulse sweep used to determine the patient's postural state.

[0035] although Figure 1 While involving SCS therapy, such as for pain treatment, in other examples, system 100 can be configured to treat any other condition that can benefit from electrical stimulation therapy. For example, system 100 can be used to treat tremor, Parkinson's disease, epilepsy, pelvic floor abnormalities (e.g., urinary incontinence or other bladder dysfunction, fecal incontinence, pelvic pain, bowel dysfunction, or sexual dysfunction), obesity, gastroparesis, or mental disorders (e.g., depression, mania, obsessive-compulsive disorder, anxiety, etc.). In this way, system 100 can be configured to provide therapy in the form of deep brain stimulation (DBS), peripheral nerve stimulation (PNS), peripheral nerve field stimulation (PNFS), cortical stimulation (CS), pelvic floor stimulation, gastrointestinal stimulation, or any other form of stimulation therapy capable of treating the condition of patient 105.

[0036] In some examples, lead 130 includes one or more sensors configured to allow IMD 110 to monitor one or more parameters of patient 105, such as patient activity, pressure, temperature, or other characteristics. One or more sensors may be provided to supplement or replace treatment delivery performed by lead 130.

[0037] The IMD 110 is configured to deliver electrical stimulation therapy to a patient 105, either alone or in combination with electrodes carried or defined by an outer housing of the IMD 110, via a selected combination of electrodes carried by one or two leads 130. The target tissue for the electrical stimulation therapy can be any tissue affected by the electrical stimulation, which can be in the form of pulses or continuous waveforms. In some examples, the target tissue includes nerves, smooth muscle, or skeletal muscle. Figure 1 In the example shown, the target tissue is tissue close to the spinal cord 120, such as within the intrathecal or epidural space of the spinal cord 120, or in some examples, an adjacent nerve branching from the spinal cord 120. The lead 130 can be introduced into the spinal cord 120 via any suitable area, such as the thoracic, cervical, or lumbar region. For example, stimulation of the spinal cord 120 can prevent pain signals from traveling through the spinal cord 120 and reaching the brain of the patient 105. The patient 105 can perceive the interruption of the pain signal as pain relief and thus as an effective treatment outcome. In other examples, stimulation of the spinal cord 120 can produce sensory abnormalities, which can reduce the patient 105's perception of pain and thus provide an effective treatment outcome.

[0038] The IMD 110 is configured to generate electrical stimulation therapy according to one or more therapeutic stimulation programs and deliver it to a target stimulation site within the patient 105 via electrodes connected to a lead 130 leading to the patient 105. The therapeutic stimulation program defines the values ​​of one or more parameters (e.g., a set of parameters) that define one aspect of the therapy delivered by the IMD 110 according to the program. For example, a therapeutic stimulation program controlling the delivery of stimulation in pulses by the IMD 110 may define the values ​​of voltage or current pulse amplitude, pulse width, pulse rate (e.g., pulse frequency), electrode combination, pulse shape, etc., of the stimulation pulses delivered by the IMD 110 according to the program.

[0039] Furthermore, the IMD 110 can be configured to deliver control stimulation to the patient 105, either alone or in combination with electrodes carried or defined by the outer housing of the IMD 110, via a combination of electrodes of the lead 130, for the detection of ECAP signals (e.g., control pulses and / or notification pulses). The tissue targeted by the stimulation may be the same as or similar to the tissue targeted by electrical stimulation therapy, but the IMD 110 may deliver stimulation pulses for ECAP signal detection via the same electrodes, at least some of the same electrodes, or different electrodes. Because control stimulation pulses can be delivered in an interleaved manner with notification pulses (e.g., when pulses configured to facilitate therapy interfere with the detection of ECAP signals or when a pulse sweep intended to detect postural status via ECAP signals does not correspond to pulses intended for therapeutic purposes), clinicians and / or users can select any desired electrode combination for the notification pulses. Similar to electrical stimulation therapy, control stimulation can be in the form of electrical stimulation pulses or continuous waveforms. In one example, each control stimulation pulse may include a balanced biphasic square pulse employing an active recharge phase. However, in other examples, control stimulation pulses may include a monophasic pulse followed by a passive recharge phase. In other examples, the control pulse may include an unbalanced biphasic portion and a passive recharge portion. Although not required, the biphasic control pulse may include an interphase interval between positive and negative phases to facilitate the propagation of a neural impulse in response to the first phase of the biphasic pulse. The control stimulus may be delivered without interrupting the delivery of the electrical stimulation notification pulse, such as during a window between consecutive notification pulses. The control pulse may induce an ECAP signal from tissue, and the IMD 110 may sense the ECAP signal via two or more electrodes on the lead 130. When the control stimulation pulse is applied to the spinal cord 120, the signal may be sensed from the spinal cord 120 by the IMD 110.

[0040] The IMD 110 can deliver control stimuli via electrodes of lead 130 to a target stimulation site within the patient 105 according to one or more ECAP test stimulation programs. One or more ECAP test stimulation programs can be stored in the storage device of the IMD 110. Each of the one or more ECAP test stimulation programs includes values ​​for one or more parameters that define an aspect of the control stimulus delivered by the IMD 110 according to the program. These parameters include current or voltage amplitude, pulse width, pulse frequency, electrode combination, and, in some examples, timing based on a notification pulse to be delivered to the patient 105. In some examples, the ECAP test stimulation program may also define the number of pulses within a pulse sweep configured to obtain corresponding ECAP signals and parameter values ​​for each of the multiple pulses, in order to obtain a growth curve that the IMD 110 can use to determine the patient's current postural state. In some examples, the IMD 110 delivers control stimuli to the patient 105 according to multiple ECAP test stimulation programs.

[0041] Users (such as clinicians or patients 105) can interact with the user interface of external programmer 150 to program IMD 110. Programming IMD 110 typically refers to the generation and transfer of commands, programs, or other information to control the operation of IMD 110. In this way, IMD 110 can receive transmitted commands and programs from external programmer 150 to control stimulation, such as electrical stimulation therapy (e.g., notification pulses) and control stimulation (e.g., control pulses). For example, external programmer 150 can transmit therapeutic stimulation programs, ECAP test stimulation programs, stimulation parameter adjustments, therapeutic stimulation program selection, ECAP test program selection, user input, or other information to control the operation of IMD 110, for example, via wireless telemetry or a wired connection.

[0042] In some cases, if the external programmer 150 is primarily intended for use by a physician or clinician, it can be characterized as a physician or clinician programmer. In other cases, if the external programmer 150 is primarily intended for use by a patient, it can be characterized as a patient programmer. A patient programmer is typically accessible to the patient 105 and, in many cases, can be a portable device that accompanies the patient 105 throughout their daily life. For example, the patient programmer can receive input from the patient 105 when the patient wishes to terminate or change electrical stimulation therapy, or when the patient perceives the stimulation being delivered. Generally, a physician or clinician programmer can support the selection and generation of programs by a clinician for use by the IMD 110, while a patient programmer can support the adjustment and selection of such programs by the patient during regular use. In other examples, the external programmer 150 may include, or be part of, an external charging device for recharging the power source of the IMD 110. In this way, a user can use one or more devices to program and charge the IMD 110.

[0043] As described herein, information can be transmitted between the external programmer 150 and the IMD 110. Therefore, the IMD 110 and the external programmer 150 can communicate wirelessly using any technology known in the art. Examples of communication technologies may include, for example, radio frequency (RF) telemetry and inductive coupling, but other technologies are also contemplated. In some examples, the external programmer 150 includes a communication head that can be positioned close to the patient's body near the IMD 110 implantation site to improve the quality or safety of communication between the IMD 110 and the external programmer 150. Communication between the external programmer 150 and the IMD 110 can occur during power transmission or separately from power transmission.

[0044] In some examples, the IMD 110, in response to commands from an external programmer 150, delivers electrical stimulation therapy via electrodes (not shown) on lead 130 to the target tissue site of the spinal cord 120 of the patient 105 according to multiple therapeutic stimulation programs. In some examples, the IMD 110 modifies the therapeutic stimulation programs as the patient 105's treatment needs evolve over time. For example, modification of the therapeutic stimulation programs may cause adjustment of at least one parameter of multiple notification pulses. The efficacy of the treatment may decrease when the patient 105 receives the same treatment for an extended period. In some cases, the parameters of multiple notification pulses can be updated automatically.

[0045] As described herein, the IMD 110 can be configured to detect an ECAP signal representing the number of nerve fibers activated by a delivered stimulus signal (e.g., a delivered pulse). Since the distance between both the stimulating and sensing electrodes and the target nerve varies for different postural states (e.g., static posture and / or active component), characteristic values ​​of one or more ECAP signals can indicate the current postural state when one or more ECAP signals are detected by the IMD 110. In one example, the IMD 110 can deliver multiple pulses defined by different parameter values ​​and detect the corresponding ECAP signal induced by each pulse. The IMD 110 can determine a relationship between the characteristic values ​​from each ECAP signal and the different parameter values ​​of the pulse, and this relationship can be different for each different postural state. In one example, the relationship can be a curve of the characteristic values ​​of the ECAP (e.g., the amplitude of the ECAP signal) versus a curve of the values ​​of the stimulation parameters (e.g., the current amplitude of the corresponding pulse) from which the characteristic values ​​are derived. Each postural state can have a corresponding curve varying in slope and / or intercept. In this way, IMD 110 can determine the pose state by comparing the determined relationship with the previously stored relationship for each of the multiple different pose states.

[0046] In some examples, the IMD 110 can detect the ECAP signal from the pulse delivered for providing treatment to the patient. In other examples, the pulse configured to provide treatment to the patient may interfere with the detection of the ECAP signal. In this way, the treatment pulse can be referred to as a notification pulse, because the parameter values ​​defining the notification pulse can be determined by the IMD 110 based on the ECAP signal triggered from different control pulses.

[0047] In one example, each notification pulse may have a pulse width greater than approximately 300 μs (in some examples, such as between approximately 300 μs and 1000 μs (i.e., 1 ms)). At these pulse widths, the IMD 110 may be insufficient to detect the ECAP signal because the notification pulse is also detected as an artifact that obscures the ECAP signal. When the pulse intended to provide therapy has these longer pulse widths, the IMD 110 can control the form of the pulse to deliver a control stimulus in order to detect the ECAP signal. The control pulse may have a smaller pulse width than the interfering therapeutic pulse (e.g., less than approximately 300 μs), such as a biphasic pulse, where each phase has a duration of approximately 100 μs. Because the control pulse can have a shorter pulse width than the notification pulse, the ECAP signal can be sensed and identified after each control pulse and used to notify the IMD 110 of any changes that should be made to the notification pulse (and, in some examples, the control pulse). Generally, the term "pulse width" refers to the total duration of each phase of a single pulse, and the phase interval where appropriate. A single pulse may include a single phase in some examples (i.e., a single-phase pulse) or two or more phases in other examples (e.g., a biphase pulse or a triphase pulse). The pulse width is defined as the time period that begins at the start time of the first phase of the pulse and ends at the end time of the last phase of the pulse (e.g., a biphase pulse with a 100 μs positive phase, a 100 μs negative phase, and a 30 μs phase interval defines a pulse width of 230 μs). In other examples, a biphase pulse may have a 120 μs positive phase, a 120 μs negative phase, and a 30 μs phase interval, defining a pulse width of 270 μs.

[0048] In this disclosure, the efficacy of electrical stimulation therapy can be indicated by one or more characteristics of the action potentials induced by stimulation pulses delivered by the IMD 110 (e.g., the amplitude of one or more peaks or the amplitude between one or more peaks, or the area under the curve of one or more peaks) (i.e., characteristic values ​​of the ECAP signal). Electrical stimulation therapy delivered by the leads 130 of the IMD 110 can induce compound action potentials in neurons within the target tissue, which travel up and down along the target tissue and eventually reach the sensing electrodes of the IMD 110. Furthermore, stimulation (e.g., therapeutic pulses and / or control pulses) can also induce at least one ECAP signal, and an ECAP in response to a control stimulus can also be a substitute for the therapeutic effect. The amount of induced action potentials (e.g., the number of action potential signals propagating in neurons) can be based on various parameters of the electrical stimulation pulses, such as amplitude, pulse width, frequency, pulse shape (e.g., slew rate at the start and / or end of the pulse), etc. The slew rate can be defined as the rate of change of the voltage and / or current amplitude of the pulse at the start and / or end of each pulse or each phase within a pulse. For example, a very high slew rate indicates a steep edge or even a near-vertical edge of the pulse, while a low slew rate indicates a longer rise (or fall) in the pulse amplitude. In some examples, these parameters contribute to the intensity of the electrical stimulation. Furthermore, the characteristics of the ECAP signal (e.g., amplitude) can vary based on the distance between the stimulating electrode and the nerve affected by the electric field generated by the delivered controlled stimulation pulse.

[0049] Exemplary techniques for adjusting stimulation parameter values ​​of a notification pulse (e.g., a pulse configured to facilitate treatment of a patient) are based on comparing values ​​of characteristics of a measured ECAP signal with target ECAP characteristic values. During the delivery of a controlled stimulation pulse defined by one or more ECAP testing stimulation procedures, the IMD 110 senses tissue potentials of the spinal cord 120 of the patient 105 via two or more electrodes inserted on leads 130 to measure the electrical activity of the tissue. The IMD 110, for example, uses electrodes on one or more leads 130 and associated sensing circuitry to sense the ECAP from the target tissue of the patient 105. In some examples, the IMD 110 receives signals indicative of the ECAP from one or more sensors (e.g., one or more electrodes and circuitry) inside or outside the patient 105. Such exemplary signals may include signals indicative of the ECAP of the tissue of the patient 105. Examples of such sensors include one or more sensors configured to measure a compound action potential of the patient 105 or indicative of the physiological effects of a compound action potential. For example, to measure the physiological effects of a compound action potential, one or more sensors may be an accelerometer, a pressure sensor, a flexure sensor, a sensor configured to detect the posture of patient 105, or a sensor configured to detect the respiratory function of patient 105. However, in other examples, external programmer 150 receives a signal indicating a compound action potential in target tissue of patient 105 and sends a notification to IMD 110.

[0050] exist Figure 1 In this example, IMD 110 is described as performing various processing and computational functions. However, external programmer 150 may alternatively perform one, several, or all of these functions. In this alternative example, IMD 110 is used to relay sensed signals to external programmer 150 for analysis, and external programmer 150 sends instructions to IMD 110 to adjust one or more parameters defining electrical stimulation therapy based on the analysis of the sensed signals. For example, IMD 110 may relay sensed signals indicating ECAP to external programmer 150. External programmer 150 may compare the parameter values ​​of ECAP with target ECAP characteristic values, and in response to the comparison, external programmer 150 may instruct IMD 110 to adjust one or more stimulation parameters that define the electrical stimulation notification pulses delivered to patient 105, and in some examples, define the control pulses delivered to the patient.

[0051] In the exemplary techniques described in this disclosure, the control of stimulation parameters and target ECAP feature values ​​can be initially set in a clinic, but can also be set and / or adjusted by the patient 105 at home. For example, the target ECAP feature can be changed to match a stimulation threshold or to become a fraction of the stimulation threshold. In some examples, the target ECAP feature and / or growth curve can be specific to the patient's corresponding different postural states. Moreover, as discussed herein, the patient's postural state can be determined based on one or more feature values ​​of the ECAP signal detected for the patient. Once the target ECAP feature value is set, the exemplary techniques allow for automatic adjustment of notification pulse parameters to maintain consistent neural activation volume and consistent therapeutic perception for the patient as the distance from the electrode to the neuron changes. The ability to change stimulation parameter values ​​also allows for long-term therapeutic efficacy and enables consistency of stimulation intensity (e.g., as indicated by the ECAP) by comparing the measured ECAP value with the target ECAP feature value. The IMD110 can perform these changes without the intervention of a physician or the patient 105.

[0052] In some examples, the system modulates the target ECAP characteristic value and / or growth rate over a period of time, such as based on changes in a stimulus threshold (e.g., a perception threshold or a detection threshold). The system can be programmed to alter the target ECAP characteristic to adjust the intensity of the notification pulse, thereby providing the patient with a sensory experience of variation (e.g., an increase or decrease in neural activation volume). Although the system can alter the target ECAP characteristic value, it can still use the received ECAP signal to adjust one or more parameter values ​​of the notification pulse and / or control pulse to satisfy the target ECAP characteristic value.

[0053] One or more devices within system 100 (such as IMD 110 and / or external programmer 150) may perform various functions as described herein. For example, IMD 110 may include a stimulation circuit system configured to deliver electrical stimulation, a sensing circuit system configured to sense multiple ECAP signals, and a processing circuit system. The processing circuit system may be configured to control the stimulation circuit system to deliver multiple electrical stimulation pulses with different amplitude values ​​and to control the sensing circuit system to detect a corresponding ECAP signal among the multiple ECAP signals after each of the multiple electrical stimulation pulses is delivered. The processing circuit system of IMD 110 may then determine the patient's postural state based on the multiple ECAP signals.

[0054] In some examples, IMD 110 may include a stimulation circuitry, a sensing circuitry, and a processing circuitry. However, in other examples, one or more additional devices may be part of a system performing the functions described herein. For example, IMD 110 may include a stimulation circuitry and a sensing circuitry, while an external programmer 150 or other external device may include a processing circuitry that at least determines the patient's postural state. For example, IMD 110 may transmit a sensed ECAP signal or data representing an ECAP signal to external programmer 150. Thus, the processes described herein can be performed by multiple devices in a distributed system. In some examples, system 100 may include one or more electrodes that deliver and / or sense electrical signals. Such electrodes may be configured to sense ECAP signals. In some examples, the same electrodes may be configured to sense signals representing instantaneous movement of the patient. In other examples, other sensors (such as accelerometers, gyroscopes, or other motion sensors) may be configured to sense movement indicating that the patient may have transitioned to a different postural state. In this way, IMD 110 can re-detect the patient's postural state from a new ECAP signal.

[0055] A patient's postural state can be a patient's static posture and / or level of activity. For example, a static posture can be prone, supine, left lateral decubitus (left side lying position), right lateral decubitus (right side lying position), semi-recumbent, sitting, or standing. Each of these positions can be an independent postural state. A postural state can also be, or alternatively, a patient's level of activity. For example, a postural state can include activities such as walking, running, cycling, driving a car, etc. In some examples, a postural state can represent both a static posture and an activity. These combinations of posture and activity can represent a patient in a static posture while moving (such as in a moving vehicle). Any of these postural states can be included in a plurality of postural states from which the IMD 110 can determine the patient's current postural state. In this way, the processing circuitry of the IMD 110 can be configured to determine a postural state by selecting a postural state from a plurality of postural states, wherein the plurality of postural states may include at least two of prone, supine, sitting, and standing positions.

[0056] As discussed herein, determined postural states can be stored in memory, transmitted to another device, and / or presented to a user via a user interface. In this way, a patient movement log can be built over time. In some examples, the IMD 110 can determine that treatment is effective by detecting larger movements in the patient where pain no longer restricts movement. In some examples, the IMD 110 can be configured to adjust the values ​​of one or more parameters that at least partially define the patient's electrical stimulation treatment based on determined postural states. For example, the IMD 110 can select specific parameter values ​​for the detected postural states, select target ECAP eigenvalues ​​for the detected postural states, and / or select growth curves of the detected postural states to increase or decrease stimulation parameters designed to maintain nerve fiber activation volume (e.g., maintain a consistent treatment level).

[0057] As discussed above, the IMD 110 can deliver multiple electrical stimulation pulses with different amplitude values ​​to elicit corresponding ECAP signals with different characteristic values ​​representing ECAP signals. Generally, the different amplitude values ​​are below the patient's discomfort threshold. However, in some examples, one or more pulses may have amplitudes exceeding the patient's discomfort threshold. In some examples, the different amplitudes may be the current or voltage amplitude of the pulses. The amplitude can be selected to have the lowest possible value to reduce any stimulation perceived by the patient. The discomfort threshold may be determined by the clinician during initial implantation, but may be updated by the clinician or the patient over time. The IMD 110 can select the amplitude of the delivered pulses to be below the discomfort threshold or below a certain percentage of that discomfort threshold (e.g., below a certain safety factor below the discomfort threshold).

[0058] In some examples, the processing circuitry of the IMD 110 can be configured to determine characteristic values ​​of multiple ECAP signals detected after each of a plurality of electrical stimulation pulses. The characteristic value of each ECAP signal is a representation of the ECAP signal based on some metric. For example, the characteristic value could be the amplitude between the N1 and P2 troughs / peaks in the ECAP signal or the area under the curve of the troughs / peaks (e.g., the P2 peak) of the ECAP signal. Therefore, these characteristic values ​​can be used as a metric derived from the ECAP signal representing the relative nerve fiber activation induced by the delivered stimulation pulse. In this way, each of the multiple ECAP signals will be associated with a corresponding characteristic value. Provided the distance between the electrode and the target nerve remains relatively constant during pulse delivery and sensing of the corresponding ECAP signal, higher amplitude pulses generally result in more nerve recruitment and a larger ECAP signal.

[0059] Then, the IMD 110 can determine a growth curve representing the relationship between characteristic values ​​of multiple ECAP signals and different amplitude values ​​of multiple electrical stimulation pulses from which the ECAP signals were induced. This is achieved when the voltage amplitude of the ECAP signal is compared with the current amplitude from each corresponding stimulation pulse (e.g., as follows). Figure 6 When comparing the determined growth curve (as shown), the growth curve can typically be linear. The IMD 110 can then compare the determined growth curve with multiple calibrated growth curves associated with the corresponding postural state among multiple postural states. These calibrated growth curves can be growth curves previously associated with the corresponding postural state (i.e., known growth curves expected for each postural state). The IMD 110 can then determine the patient's postural state based on the comparison. For example, the IMD 110 can select the postural state with the calibrated growth curve that is closest to the determined growth curve.

[0060] The delivery of electrical stimulation pulses with different amplitude values ​​can be referred to as a pulse sweep. For example, the IMD 110 can be configured to control the stimulation circuitry system to deliver multiple electrical stimulation pulses as a pulse sweep comprising iteratively increasing amplitude values. However, in other examples, the pulses may have decreasing amplitude values ​​or randomly selected amplitude values. The IMD 110 can detect the ECAP signal from the previous stimulation pulse before delivering the next stimulation pulse. Therefore, the IMD 110 can schedule a detection time window between the delivery of each pulse within the pulse sweep.

[0061] In some examples, if patient movement is detected, the IMD 110 can restart the pulse sweep. Thus, the IMD can control the stimulation circuitry to deliver a first set of electrical stimulation pulses during a first time period, from which the corresponding ECAP signal in the first set of ECAP signals can be detected. However, the IMD 110 can be configured to recognize transient patient movement during the first time period. This transient movement could be a coughing, sneezing, laughing, or bending movement that could cause a change in the distance between the electrode and the target tissue. In response to recognizing transient movement, the IMD 110 can terminate the first time period and the delivery of the first set of electrical stimulation pulses and discard the first set of ECAP signals. The first set of ECAP signals may not be valuable because the patient's postural state is likely to change. The IMD 110 can monitor the transient movement and then determine that the transient movement has ended. For example, the IMD 110 can determine that no further movement has been detected within a predetermined time period. Then, after the transient movement has ended, the IMD 110 can be configured to control the stimulation circuitry to deliver a second set of electrical stimulation pulses and control the sensing circuitry to detect a second set of ECAP signals. This process can continue until the entire frequency sweep is complete. In this way, the IMD 110 can restart the pulse frequency sweep in response to determining that the instantaneous movement has ended in order to attempt to determine the patient's new postural status from the ECAP signal.

[0062] In some examples, the IMD 110 can detect transient movement from the ECAP signal itself during a frequency sweep. For instance, the IMD 110 can determine that the ECAP characteristic value is not within an acceptable deviation from a linear increase with increasing pulse intensity. Since the overall growth curve of postural states can typically be linear, the IMD 110 can analyze the characteristic value determined during a subsequent ECAP signal during a frequency sweep to determine whether the characteristic value begins to deviate from the expected linear growth curve by a predetermined deviation (e.g., magnitude or percentage). If the IMD 110 determines that the ECAP characteristic value increases or decreases exponentially or logarithmically, or that the characteristic value oscillates during a frequency sweep, the IMD 110 can determine that transient patient movement could be the cause of unexpected ECAP characteristic values.

[0063] In other examples, the IMD 110 may use other detected signals and / or sensors to detect transient movement. In one example, the IMD 110 may receive electromyography (EMG) signals from electrodes of lead 130 or some other electrodes of connected leads, or from a separate device, during a frequency sweep. The IMD 110 may analyze the EMG signals and determine that the patient 105 has made a transient movement during the frequency sweep. In other examples, the IMD 110 may receive information indicating transient movement from other sensors during the frequency sweep. For example, the sensors may include one or more accelerometers (or other movement detection devices), and the processing circuitry of the IMD 110 may receive information from the sensors and determine that the patient 105 has made a transient movement based on the movement detected by one or more accelerometers. In some examples, the IMD 110 may monitor information from two or more sensors and / or use two or more sensing modalities, and determine the transient movement that occurred during the frequency sweep based on this information from these two or more sensors and / or these two or more modalities. If any of the sensors and / or sensing modes indicates that a momentary movement has occurred, the IMD 110 may determine the momentary movement. Alternatively, the IMD 110 may require information from at least two or more sensors and / or sensing modes to confirm that a momentary movement has occurred.

[0064] The IMD 110 can also determine a calibration growth curve for each of a plurality of postural states. For example, the IMD 110 can be configured to control the stimulation circuitry system to deliver a plurality of calibration electrical stimulation pulses with different amplitude values ​​when the patient presents that postural state, and to control the sensing circuitry system to detect a corresponding calibration ECAP signal among a plurality of calibration ECAP signals after each of the plurality of calibration electrical stimulation pulses is delivered. The IMD 110 can then determine calibration characteristic values ​​for the plurality of calibration ECAP signals, wherein each of the plurality of calibration ECAP signals is associated with a corresponding characteristic value among the calibration characteristic values. The IMD 110 can then determine a corresponding calibration growth curve among a plurality of calibration growth curves, which represents the relationship between the calibration characteristic values ​​of the plurality of calibration ECAP signals and the different amplitude values ​​of the plurality of calibration electrical stimulation pulses from which the calibration ECAP signals were induced. The IMD 110 can repeat this process at any time as a scheduled task or in response to a triggering event. For example, IMD 110 may recalibrate these calibrated growth curves in response to receiving information indicating ineffective treatment, a user request to recalibrate the growth curves, and / or determining that a predetermined time has elapsed.

[0065] As described herein, the IMD 110 can then compare the growth curve determined during posture state sensing with the most currently calibrated growth curve for the posture state. The IMD 110 can select the posture state associated with the calibrated growth curve that is closest to the determined growth curve. The comparison may include comparing the slope and / or offset of the growth curves (e.g., the magnitude of the y-intercept of the growth curve). In some examples, the IMD 110 may employ an acceptable deviation of the growth curve compared to the calibrated growth curve before the IMD 110 would definitively identify the posture state. This mechanism prevents the IMD 110 from identifying the posture state if the determined growth curve does not properly match any calibrated growth curves in memory. If the determined growth curve is outside the acceptable deviation, the IMD 110 may responsively perform another frequency sweep against the ECAP signal to generate a new growth curve. In other examples, the IMD 110 may determine the posture state from another sensor, such as an accelerometer. In some examples where the IMD 110 cannot definitively determine the patient's postural state, the IMD 110 may revert to a "safe mode" in which stimulus parameter value adjustments are performed based on a conservative parameter value adjustment scheme or parameter value adjustments are disabled based on postural state detection.

[0066] Although in one example the IMD 110 takes the form of an SCS device, in other examples the IMD 110 takes the form of any combination of the following devices: such as a deep brain stimulation (DBS) device, an implantable cardioverter defibrillator (ICD), a pacemaker, a cardiac resynchronization therapy device (CRT-D), a left ventricular assist device (LVAD), an implantable sensor, an orthopedic device, or a drug pump. Furthermore, the techniques of this disclosure can be used to determine stimulation thresholds (e.g., sensing thresholds and detection thresholds) associated with any of the aforementioned IMDs, and then use these stimulation thresholds to indicate the intensity of treatment (e.g., stimulation level).

[0067] Figure 2 This is a block diagram illustrating an exemplary configuration of components of an IMD 200 according to one or more technologies disclosed herein. The IMD 200 may be... Figure 1 An example of IMD 110. In Figure 2 In the example shown, IMD 200 includes a stimulus generation circuit system 202, a switching circuit system 204, a sensing circuit system 206, a telemetry circuit system 208, a processing circuit system 210, a storage device 212, a sensor 222, and a power source 224.

[0068] exist Figure 2 In the illustrated example, storage device 212 stores patient posture data 240, stimulation parameter settings 242, and calibration instructions 244 in a separate memory or a separate area within storage device 212. In some examples, stimulation parameter settings 242 may include stimulation parameter values ​​for different stimulation procedures that can be selected by a clinician or patient for treatment. In this way, each stored treatment stimulation procedure or set of stimulation parameter values ​​in stimulation parameter settings 242 defines the values ​​of a set of electrical stimulation parameters (e.g., a set of stimulation parameters), such as stimulation electrode combinations, electrode polarity, current or voltage amplitude, pulse width, pulse rate, and pulse shape. Storage device 212 may also store ECAP test stimulation procedures as part of stimulation parameter settings 242 or as a separate memory area, which defines the values ​​of a set of electrical stimulation parameters (e.g., a control set of stimulation parameters) configured to elicit a detectable ECAP signal, such as stimulation electrode combinations, electrode polarity, current or voltage amplitude, pulse width, pulse rate, and pulse shape. The ECAP test stimulation procedure may also include additional information, such as instructions on when to deliver control pulses based on the pulse width and / or frequency of the notification pulse defined in stimulation parameter setting 242.

[0069] Therefore, in some examples, the stimulation generation circuit system 202 generates an electrical stimulation signal according to the described electrical stimulation parameters. Other ranges of stimulation parameter values ​​may also be useful and may depend on the target stimulation site within the patient 105. Although stimulation pulses are described, the stimulation signal can be of any form, such as a continuous-time signal (e.g., a sine wave). The switching circuit system 204 may include one or more switch arrays, one or more multiplexers, one or more switches (e.g., a switch matrix or other set of switches), or other circuit systems configured to direct the stimulation signal from the stimulation generation circuit system 202 to one or more of the electrodes 232, 234, or to direct a sensed signal from one or more of the electrodes 232, 234 to the sensing circuit system 206. In other examples, the stimulation generation circuit system 202 and / or the sensing circuit system 206 may include a sensing circuit system to direct signals to and / or from one or more of the electrodes 232, 234, which may or may not include the switching circuit system 204.

[0070] Sensing circuitry 206 is configured to monitor signals from any combination of electrodes 232, 234. In some examples, sensing circuitry 206 includes one or more amplifiers, filters, and analog-to-digital converters. Sensing circuitry 206 can be used to sense physiological signals, such as ECAP signals. In some examples, sensing circuitry 206 detects ECAP from a specific combination of electrodes 232, 234. In some cases, the specific combination of electrodes used to sense ECAP includes electrodes different from the set of electrodes 232, 234 used to deliver stimulation pulses. Alternatively, in other cases, the specific combination of electrodes used to sense ECAP includes at least one electrode from the same set of electrodes used to deliver stimulation pulses to patient 105. Sensing circuitry 206 can provide signals to an analog-to-digital converter for conversion into digital signals for processing, analysis, storage, or output by processing circuitry 210.

[0071] Under the control of the processing circuit system 210, the telemetry circuit system 208 supports IMD 200 and external programmers ( Figure 2Wireless communication between the IMD 200 (not shown) or another computing device. As an update to the program, the processing circuitry 210 of the IMD 200 can receive values ​​of various stimulation parameters (such as amplitude and electrode combinations) from an external programmer via the telemetry circuitry 208. The processing circuitry 210 can store updates to the stimulation parameter settings 242 or any other data in the storage device 212. The telemetry circuitry 208 in the IMD 200, as well as the telemetry circuitry in other devices and systems described herein (such as external programmers), can communicate via radio frequency (RF) communication technology. Furthermore, the telemetry circuitry 208 can interact with the external medical device programmer (IMD 200) via proximal sensor interaction with the external programmer. Figure 2 (Not shown) communicates. An external programmer can be... Figure 1 An example of an external programmer 150. Thus, the telemetry circuit system 208 can continuously, periodically, or upon request from the IMD 110 or the external programmer, send information to the external programmer.

[0072] Processing circuitry system 210 may include one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a discrete logic circuit system, or any other processing circuitry system configured to provide the functionality attributed to processing circuitry system 210, which may herein be embodied as firmware, hardware, software, or any combination thereof. Processing circuitry system 210 controls stimulus generation circuitry system 202 to generate stimulus signals according to stimulus parameter settings 242 stored in storage device 212 and any other instructions, to apply stimulus parameter values ​​specified by one or more programs, such as the amplitude, pulse width, pulse rate, and pulse shape of each stimulus signal in the stimulus signal.

[0073] exist Figure 2In the example shown, the set of electrodes 232 includes electrodes 232A, 232B, 232C, and 232D, and the set of electrodes 234 includes electrodes 234A, 234B, 234C, and 234D. In other examples, a single lead may include all eight electrodes 232 and 234 along a single axial length of the lead. The processing circuitry 210 also controls the stimulus generation circuitry 202 to generate stimulus signals and apply these stimulus signals to a selected combination of electrodes 232, 234. In some examples, the stimulus generation circuitry 202 includes a switching circuit (instead of or as a supplement to the switching circuitry 204) that can couple the stimulus signals to a selected conductor within the lead 230, which in turn delivers the stimulus signals through the selected electrodes 232, 234. Such a switching circuit can be a switch array, a switch matrix, a multiplexer, or any other type of switching circuit, which is configured to selectively couple stimulation energy to selected electrodes 232, 234 and selectively sense the patient using the selected electrodes 232, 234. Figure 2 Bioelectric nerve signals of the spinal cord (not shown in the image).

[0074] However, in other examples, the stimulus generation circuit system 202 does not include a switching circuit, and the switching circuit system 204 is not connected between the stimulus generation circuit system 202 and the electrodes 232, 234. In these examples, the stimulus generation circuit system 202 includes multiple pairs of voltage sources, current sources, voltage absorbers, or current absorbers connected to each of the electrodes 232, 234, such that each pair of electrodes has a unique signal circuit. In other words, in these examples, each of the electrodes 232, 234 is independently controlled via its own signal circuit (e.g., via a combination of a regulated voltage source and absorber or a regulated current source and absorber), which is the opposite of the switching signal between the electrodes 232, 234.

[0075] The electrodes 232, 234 on the corresponding leads 230 can be constructed using a variety of different designs. For example, one or both of the leads 230 may include one or more electrodes at each longitudinal location along the length of the lead, such as including one electrode at different peripheral locations around the periphery of the lead at each of locations A, B, C, and D. In one example, the electrodes may be electrically coupled to the stimulation generation circuitry system 202, for example, via a corresponding wire of a straight or coiled connector within the lead housing that extends to the proximal end of the lead, through the switching circuitry system 204 and / or the stimulation generation circuitry system 202. In another example, each electrode in the leads may be an electrode deposited on a thin film. The thin film may include conductive traces for each electrode that extend along the length of the film to the proximal end connector. The thin film may then be wrapped (e.g., spirally wrapped) around an internal component to form the lead 230. These and other configurations can be used to form leads with complex electrode geometries.

[0076] Although the sensing circuit system 206 is in Figure 2 The stimulation generation circuitry system 202 and the processing circuitry system 210 are integrated into a common housing. However, in other examples, the sensing circuitry system 206 may be located in a separate housing from the IMD 200 and may communicate with the processing circuitry system 210 via wired or wireless communication technologies. In some examples, one or more of electrodes 232 and 234 are adapted to sense the ECAP. For example, electrodes 232 and 234 may sense the voltage amplitude of a portion of the ECAP signal, wherein the sensed voltage amplitude (such as the voltage difference between features within the signal) is characteristic of the ECAP signal.

[0077] Storage device 212 can be configured to store information within IMD 200 during operation. Storage device 212 may include a computer-readable storage medium or a computer-readable storage device. In some examples, storage device 212 includes one or more of short-term memory or long-term memory. Storage device 212 may include, for example, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), magnetic disk, optical disk, flash memory, or electrically programmable memory (EPROM) or electrically erasable programmable memory (EEPROM). In some examples, storage device 212 is used to store data indicating instructions executed by processing circuitry system 210. As discussed above, storage device 212 is configured to store patient posture state data 240, stimulation parameter settings 242, and calibration instructions 244.

[0078] Patient posture state data 240 may store growth curves or other ECAP-related data and indications of one or more posture states associated with those growth curves or other ECAP-related data. For example, each posture state may be associated with a corresponding growth curve for an ECAP characteristic value. In some examples, multiple posture states may be associated with the same growth curve. In this way, processing circuitry system 210 may compare newly determined growth curves (determined from multiple ECAP signals) with growth curves stored in patient posture state data 240 to determine the patient's current posture state at the time the ECAP signal was detected.

[0079] Calibration instruction 244 may include instructions on how to determine the calibrated growth curve for each posture state and / or when to recalibrate the calibrated growth curve. For example, calibration instruction 244 may specify the parameter values ​​of the pulses used to trigger the ECAP signal, the number of pulses and ECAP signals that should be used to define each growth curve, the type of ECAP characteristic value to be used when defining the growth curve, or any other similar information.

[0080] In some examples, storage device 212 may also store instructions on how processing circuitry system 210 may adjust stimulation pulses in response to a detected postural state. For example, processing circuitry system 210 may select a specific procedure or set of stimulation parameter values ​​associated with a particular posture. In other examples, processing circuitry system 210 may be selected to define how the gain value or other factors of the stimulation parameter values ​​may be changed based on detected ECAP feature values. Processing circuitry system 210 may monitor ECAP feature values ​​obtained from the ECAP signal to modulate the stimulation parameter values ​​(e.g., increase or decrease stimulation intensity to maintain the target therapeutic effect). Since the target ECAP feature value can vary for different postural states, processing circuitry system 210 may select an appropriate target ECAP feature value for the patient's current postural state and modulate the stimulation parameter values ​​based on the postural state-specific target ECAP feature value.

[0081] Sensor 222 may include one or more sensing elements that sense values ​​of corresponding patient parameters, such as posture. As described above, electrodes 232 and 234 may be electrodes that sense characteristic values ​​of the ECAP signal. Sensor 222 may include one or more accelerometers, optical sensors, chemical sensors, temperature sensors, pressure sensors, or any other type of sensor. Sensor 222 may output patient parameter values ​​that can be used as feedback to control treatment delivery. For example, sensor 222 may indicate patient activity, and processing circuitry 210 may increase the frequency of control pulses and ECAP sensing in response to the detection of increased patient activity. In one example, processing circuitry 210 may initiate control pulses and corresponding ECAP sensing in response to a signal from sensor 222 indicating that patient activity has exceeded an activity threshold. In some examples, processing circuitry 210 may initiate a new sweep of the ECAP signal to determine a growth curve in response to the detection of an exceeded activity threshold. Conversely, processing circuitry 210 may decrease the frequency of control pulses and ECAP sensing (e.g., sweep frequency) in response to the detection of decreased patient activity. For example, in response to sensor 222 no longer indicating that the sensed patient activity exceeds a threshold, processing circuitry 210 can pause or stop delivering control pulses and ECAP sensing. In this way, processing circuitry 210 can dynamically deliver control pulses and sense ECAP signals based on patient activity to reduce system power consumption when the distance between the electrode and neuron cannot be changed, and to increase the system's response to changes in ECAP when the distance between the electrode and neuron may change. IMD 200 may include additional sensors coupled within the housing of IMD 200 and / or via one of the leads or other leads in lead 130. Furthermore, for example, IMD 200 may wirelessly receive sensor signals from remote sensors via telemetry circuitry 208. In some examples, one or more of these remote sensors may be located outside the patient's body (e.g., supported on an external surface of the skin, attached to clothing, or otherwise positioned outside the patient 105). In some examples, the signal from sensor 222 indicates a location or body state (e.g., sleeping, awake, sitting, standing, etc.), and the processing circuitry system 210 can select a target ECAP feature value based on the indicated location or body state.

[0082] Power source 224 is configured to deliver operating power to components of IMD 200. Power source 224 may include a battery and power generation circuitry for generating operating power. In some examples, the battery is rechargeable to allow for long-term operation. In some examples, recharging is achieved through near-side inductive interaction between an external charger and an inductive charging coil within IMD 200. Power source 224 may include any one or more of a variety of battery types, such as nickel-cadmium batteries and lithium-ion batteries.

[0083] Figure 3 This is a block diagram illustrating an exemplary configuration of components of an exemplary external programmer 300. The external programmer 300 may be... Figure 1 An example of an external programmer 150. Although the external programmer 300 is generally described as a handheld device, it can be a larger portable device or a more fixed device. Furthermore, in other examples, the external programmer 300 may be included as part of an external charging device or include the functionality of an external charging device. Figure 3 As shown, the external programmer 300 may include a processing circuitry 352, a storage device 354, a user interface 356, a telemetry circuitry 358, and a power source 360. The storage device 354 may store instructions that, when executed by the processing circuitry 352, cause the processing circuitry 352 and the external programmer 300 to provide the functions attributed to the external programmer 300 throughout this disclosure. Each of these components, circuitries, or modules may include a circuitry configured to perform some or all of the functions described herein. For example, the processing circuitry 352 may include a processing circuitry configured to perform the processes discussed with respect to the processing circuitry 352.

[0084] Generally, external programmer 300 includes any suitable hardware arrangement that, individually or in combination with software and / or firmware, executes the technologies belonging to external programmer 300 and its processing circuitry 352, user interface 356, and telemetry circuitry 358. In various examples, external programmer 300 may include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry system, and any combination of such components. In various examples, external programmer 300 may also include a storage device 354, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, hard disk, CD-ROM, containing executable instructions for causing one or more processors to perform actions belonging to those instructions. Furthermore, although processing circuitry 352 and telemetry circuitry 358 are described as separate modules, in some examples, processing circuitry 352 and telemetry circuitry 358 are functionally integrated. In some examples, processing circuitry 352 and telemetry circuitry 358 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0085] Storage device 354 (e.g., a storage device) may store instructions that, when executed by processing circuitry system 352, cause processing circuitry system 352 and external programmer 300 to provide the functions attributed to external programmer 300 throughout this disclosure. For example, storage device 354 may include instructions that cause processing circuitry system 352 to retrieve a parameter set from memory, select a spatial electrode mode, or receive user input and send a corresponding command to IMD 200, or instructions for any other function. Furthermore, storage device 354 may include multiple programs, each including a parameter set defining therapeutic or control stimulation. Storage device 354 may also store data received from a medical device (e.g., IMD 110). For example, storage device 354 may store ECAP-related data recorded at the sensing module of the medical device, and storage device 354 may also store data from one or more sensors of the medical device.

[0086] User interface 356 may include buttons or a keypad, lights, a speaker for voice commands, and a display such as a liquid crystal display (LCD), a light-emitting diode (LED) display, or an organic light-emitting diode (OLED) display. In some examples, the display includes a touchscreen. User interface 356 may be configured to display any information related to the delivery of electrical stimulation, identified postural states, sensed patient parameter values, or any other such information. User interface 356 may also receive user input (e.g., an indication of when the patient perceives a stimulation pulse). Input may be in the form of, for example, pressing a button on a keypad or selecting an icon from a touchscreen. Input may request the start or stop of electrical stimulation, may request a new spatial electrode pattern or a change to an existing spatial electrode pattern, or may request other changes to the delivery of electrical stimulation. During the calibration process of obtaining ECAP signals for different postural states, user interface 356 may present the postural state that the patient should be in, and user interface 356 may receive user input confirming that the patient is in the requested postural state. In other examples, user interface 356 may receive user input indicating the patient's postural state and generate a relationship (e.g., a calibrated growth curve) to the detected ECAP feature values ​​obtained during calibration for that indicated postural state.

[0087] Under the control of the processing circuitry 352, the telemetry circuitry 358 can support wireless communication between the medical device and the external programmer 300. The telemetry circuitry 358 can also be configured to communicate with another computing device via wireless communication technology, or directly with another computing device via a wired connection. In some examples, the telemetry circuitry 358 provides wireless communication via RF or a near-side sensing medium. In some examples, the telemetry circuitry 358 includes an antenna, which can take various forms, such as an internal antenna or an external antenna.

[0088] Examples of local wireless communication technologies that can be used to facilitate communication between the external programmer 300 and the IMD 110 include those based on 802.11 or... Radio frequency communication using a specification set or other standard or proprietary telemetry protocol. In this way, other external devices can be able to communicate with the external programmer 300 without establishing a secure wireless connection. As described herein, the telemetry circuitry system 358 can be configured to transmit spatial electrode movement patterns or other stimulation parameter values ​​to the IMD 110 for the delivery of electrical stimulation therapy.

[0089] In some examples, the selection of stimulation parameters or therapeutic stimulation procedures is transmitted to a medical device for delivery to the patient (e.g., Figure 1(Patient 105). In other examples, the treatment may include medication, activity, or other instructions that patient 105 must perform themselves or that a caregiver must perform for patient 105. In some examples, the external programmer 300 provides visual, auditory, and / or tactile notifications indicating the presence of new instructions. In some examples, the external programmer 300 requires receiving user input to confirm that the instruction has been completed.

[0090] The user interface 356 of the external programmer 300 can also be configured to receive instructions from a clinician to update one or more therapeutic stimulation programs or to update calibrated growth curves for one or more postural states. Updating the therapeutic stimulation programs and calibrated growth curves may include changing one or more parameters of the stimulation pulses delivered by the medical device according to the program, such as the amplitude, pulse width, frequency, and pulse shape of the notification and / or control pulses. The user interface 356 can also receive instructions from the clinician to start or stop any electrical stimulation (including therapeutic and control stimuli).

[0091] Power source 360 ​​is a component configured to deliver operating power to external programmer 300. Power source 360 ​​may include a battery and power generation circuitry for generating operating power. In some examples, the battery is rechargeable to allow for long-term operation. Recharging can be achieved by electrically coupling power source 360 ​​to a bracket or plug connected to an alternating current (AC) outlet. Alternatively, recharging can be achieved through near-side inductive interaction between an external charger and an inductive charging coil within external programmer 300. In other examples, conventional batteries (e.g., nickel-cadmium or lithium-ion batteries) may be used. Furthermore, external programmer 300 may be directly coupled to an AC outlet for operation.

[0092] Figure 3 The architecture of the external programmer 300 shown in this disclosure is illustrated as an example. The techniques described in this disclosure can be used in... Figure 3 This includes the exemplary external programmer 300 and other types of systems not specifically described herein. Nothing in this disclosure should be construed as limiting the technology of this disclosure to... Figure 3 An exemplary architecture is shown.

[0093] Figure 4 This is an exemplary evoked compound action potential (ECAP) curve 402 for sensing a corresponding stimulus impulse according to one or more techniques of this disclosure. Figure 4As shown, graph 402 illustrates exemplary ECAP signals 404 (dashed line) and 406 (solid line). In some examples, each of ECAP signals 404 and 406 is sensed by a control pulse delivered from the protected cathode, wherein the control pulse is a biphase pulse that includes an interphase interval between each positive and negative phase of the pulse. In some such examples, the protected cathode includes an 8-electrode lead (e.g., ...). Figure 1 The stimulation electrode is located at one end of the lead 130, while two sensing electrodes are located at the other end of the 8-electrode lead. The ECAP signal 404 shows the voltage amplitude sensed as a result of a sub-detection threshold stimulation pulse. In other words, the stimulation pulse does not elicit a detectable ECAP signal in the ECAP signal 404. Peak 408 of the ECAP signal 404 is detected, and this peak represents an artifact of the delivered stimulation pulse (e.g., a control pulse that may or may not contribute to the therapeutic effect on the patient). However, no propagation signal is detected after the artifact in the ECAP signal 404 because the control pulse is sub-detection threshold.

[0094] Compared to ECAP signal 404, ECAP signal 406 represents the voltage amplitude detected from the over-detection threshold control pulse. Peak 408 of ECAP signal 406 is detected, and this peak represents an artifact of the delivered control pulse. After peak 408, ECAP signal 406 also includes peaks P1, N1, and P2, which are three typical peaks representing the propagating action potential from ECAP. The exemplary duration of the artifacts with peaks P1, N1, and P2 is approximately 1 millisecond (ms). When the ECAP of ECAP signal 406 is detected, different features can be identified. For example, the feature of ECAP can be an amplitude between N1 and P2. This N1-P2 amplitude can be easily detected even if the artifact is projected onto a relatively large signal P1, and the N1-P2 amplitude can be minimally affected by electronic drift in the signal. In other examples, the feature of ECAP used to detect the patient's postural state and / or control notification pulses can be the amplitude of P1, N1, or P2 relative to a neutral voltage or zero voltage. In some examples, the characteristic of ECAP can be the sum of two or more of peaks P1, N1, or P2. In other examples, the characteristic of the ECAP signal 406 can be the area under one or more of peaks P1, N1, and / or P2. In other examples, the characteristic of ECAP can be the ratio of one of peaks P1, N1, or P2 to another of these peaks. In some examples, the characteristic of ECAP is the slope between two points in the ECAP signal, such as the slope between N1 and P2. In other examples, the characteristic of ECAP can be the time between two points in the ECAP, such as the time between N1 and P2. The time between two points in the ECAP signal can be referred to as the delay of ECAP and can indicate the type of fiber captured by the control pulse. An ECAP signal with a lower delay (i.e., a smaller delay value) indicates a higher percentage of nerve fibers with faster signal propagation, while an ECAP signal with a higher delay (i.e., a larger delay value) indicates a higher percentage of nerve fibers with slower signal propagation. In other examples, other characteristics of the ECAP signal can be used.

[0095] As long as the amplitude of the control pulse is greater than a threshold, the amplitude of the ECAP signal typically increases with the increase of the pulse amplitude, causing nerve depolarization and signal propagation. As discussed herein, the relationship between the ECAP signal amplitude and the pulse amplitude also depends on the patient's postural state, and therefore the relationship between the ECAP signal and the pulse amplitude changes for different postural states. Target ECAP characteristics (e.g., target ECAP amplitude) can be determined based on the ECAP signal detected from the control pulse when determining effective treatment delivery of the notification pulse to the patient 105. Therefore, the ECAP signal represents the distance between the stimulating electrode and the nerve appropriate for the stimulation parameter values ​​of the notification pulse delivered at that time. The IMD 110 can attempt to modify the notification pulse parameter values ​​and maintain the target ECAP characteristic values ​​during notification pulse delivery by using detected postural states from the ECAP characteristic values ​​and detected changes in the measured ECAP characteristic values.

[0096] Figure 5 This is a timing diagram 500A illustrating an example of an electrical stimulation pulse and a corresponding sensed ECAP according to one or more techniques of this disclosure. For convenience, refer to... Figure 2 IMD 200 pairs Figure 5 The following description is provided. As shown in the figure, timing diagram 500A includes a first channel 502, multiple control pulses 504A–504N (collectively referred to as "control pulses 504"), a second channel 506, multiple corresponding ECAPs 508A–508N (collectively referred to as "ECAP 508"), and multiple stimulus interference signals 509A–509N (collectively referred to as "stimulus interference signals 509"). Figure 5 In the example, control pulse 504 can be configured to promote or not promote treatment. In either case, control pulse 504 can trigger a corresponding ECAP 508 to achieve the purpose of determining the relationship between the parameter value of control pulse 504 and ECAP 508 (such as a growth curve indicating the patient's postural state).

[0097] The first channel 502 is a time / voltage (and / or current) graph indicating the voltage (or current) of at least one of the electrodes 232, 234. In one example, the stimulating electrode of the first channel 502 may be located on the side of the lead opposite to the sensing electrode of the second channel 506. The control pulse 504 may be an electrical pulse delivered to the patient's spinal cord by at least one of the electrodes 232, 234, and the control pulse 504 may be a balanced biphasic square pulse with phase intervals. In other words, each control pulse in the control pulse 504 is shown to have a negative phase and a positive phase separated by phase intervals. For example, the control pulse 504 may have a negative voltage, the same amount of time and amplitude as when it has a positive voltage. Note that the negative voltage phase may precede or follow the positive voltage phase. The control pulse 504 may be delivered according to instructions stored in the storage device 212 of the IMD 200.

[0098] In some examples, each control pulse in control pulse 504 may be part of a pulse sweep configured to determine the relationship between the stimulation parameter value of the pulse and the characteristic value of the resulting corresponding ECAP 508. For example, the relationship may be a growth curve of the ECAP voltage amplitude against the pulse current amplitude. In this way, each control pulse in control pulse 504 may be different from each other due to the parameter value (the iteratively increasing current amplitude). In one example, control pulse 504 may have a pulse width of less than about 300 microseconds (e.g., the total time of the positive phase, negative phase, and phase interval is less than 300 microseconds). In another example, for each phase of a biphasic pulse, control pulse 504 may have a pulse width of about 100 μs. In some examples, the pulse width of control pulse 504 may be longer than 300 microseconds, provided that the pulse width does not interfere with the detection of one or more desired characteristics of the induced ECAP 508. Figure 5 As shown, control pulse 504 can be delivered via channel 502. The delivery of control pulse 504 can be delivered via lead 230 in the protected cathode electrode assembly. For example, if lead 230 is a linear 8-electrode lead, the protected cathode assembly consists of a center cathode electrode and an anode electrode immediately adjacent to that cathode electrode.

[0099] The second channel 506 is a time / voltage (and / or current) graph indicating the voltage (or current) at at least one of the electrodes 232, 234. In one example, the electrode of the second channel 506 may be located on the side of the lead opposite to the electrode of the first channel 502. In response to a control pulse 504, an ECAP 508 can be sensed from the patient's spinal cord at electrodes 232, 234. The ECAP 508 is an electrical signal that can propagate along the nerve away from the origin of the control pulse 504. In one example, the ECAP 508 is sensed by an electrode different from the electrode used to deliver the control pulse 504. Figure 5 As shown, ECAP 508 can be recorded on the second channel 506.

[0100] Stimulus interference signals 509A, 509B, and 509N (e.g., artifacts of the stimulation pulse) can be sensed by lead 230 and can be sensed during the same time period as the delivery of control pulse 504. Because the amplitude and intensity of these interference signals may be greater than ECAP 508, any ECAP arriving at IMD 200 during the occurrence of stimulation interference signal 509 may not be adequately sensed by the sensing circuitry 206 of IMD 200. However, ECAP 508 can be adequately sensed by the sensing circuitry 206 because each ECAP 508, or at least a portion of ECAP 508 including one or more desired features of ECAP 508, decreases after each control pulse 504 ends. Figure 5 As shown, the stimulation interference signals 509 and ECAP 508 can be recorded on channel 506.

[0101] In some examples, for instance, IMD 200 may continuously deliver a full set of control pulses 504 (e.g., a sweep) without any other intermediate pulses to detect ECAP 508, from which corresponding characteristic values ​​are determined. IMD 200 can then determine the relationship between the characteristic values ​​from ECAP 508 and different parameter values ​​of control pulses 504. In one example, the sweep of pulses 504 may be delivered by IMD 200 during intervals between the delivery of treatment pulses. In other examples, the sweep of pulses 504 may be at least partially interleaved with different stimulation pulses (e.g., one or more notification pulses) configured to facilitate treatment for the patient. Thus, one or more pulses may be configured to facilitate treatment that can be delivered between at least two control pulses in control pulses 504.

[0102] Figure 6 Graph 600 is an example of growth curves 604, 606, and 608 illustrating the relationship between ECAP amplitude and pulse amplitude under different posture states. (See graph 600.) Figure 6 As shown, graph 600 illustrates exemplary ECAP eigenvalues ​​602, which are represented as dots, squares, and triangles corresponding to different current amplitudes of the stimulus pulse. Typically, ECAP will be undetectable until the stimulus pulse amplitude reaches a certain threshold (in...). Figure 6 In the example, approximately at a current of 4.5mA. Then, as the current amplitude increases, the ECAP amplitude also increases approximately linearly. This linear relationship is shown by each of the growth curves 604, 606, and 608.

[0103] The slope of each growth curve that increases linearly may be referred to herein as “gain” because it indicates the relationship between the sensed ECAP amplitude (e.g., a characteristic value) and the pulse amplitude. In other words, the gain value can represent the slope of a growth curve defined by the values ​​of characteristics of the ECAP signal (e.g., amplitude, such as the N1-P2 amplitude of the ECAP signal or the amplitude of any peak), which is triggered by a corresponding calibrated stimulation pulse delivered to the patient and is at least partially defined by different values ​​of stimulation parameters (e.g., current amplitude, voltage amplitude, or pulse width). As described herein, the gain value, or slope, can be associated with a specific postural state among multiple postural states. In some examples, the gain value for a particular patient can be used to dynamically adjust the notification pulse amplitude and control amplitude based on the sensed ECAP amplitude.

[0104] Each of growth curves 604, 606, and 608 represents a growth curve for a corresponding postural state. For example, four characteristic values ​​602 (circles) from the corresponding ECAP signal form a growth curve 604 that can be associated with a supine posture. Four characteristic values ​​602 (squares) from the corresponding ECAP signal form a growth curve 606 that can be associated with a sitting posture. Four characteristic values ​​602 (triangles) from the corresponding ECAP signal form a growth curve 608 that can be associated with a prone posture. Growth curves 604, 606, and 608 can be examples of calibrated growth curves. Each of growth curves 604, 606, and 608 can have a corresponding slope, such as a slope of approximately 32 μV / mA for growth curve 604, approximately 24 μV / mA for growth curve 606, and approximately 10 μV / mA for growth curve 608. Therefore, if the later-determined growth curve from the pulse sweep and the corresponding ECAP signal produce a slope of approximately 24 μV / mA, then IMD can determine that the patient's postural state is sitting upright. In this way, due to the different distances between the electrode and the target nerve in these different postural states, the different growth curves appear as a function of the patient's postural state.

[0105] For example, IMD 200 can generate a calibration growth curve (e.g., in terms of the relationship between parameter values ​​and ECAP characteristic values) after implantation and before treatment delivery. IMD 200 can periodically regenerate the calibration growth curve over time. For example, IMD 200 may have instructions indicating the time interval at which IMD 200 is triggered to regenerate the calibration growth curve upon expiration. This recalibration may be useful over time because electrodes may migrate in the tissue, nerves may become desensitized to stimulation, and / or electrodes may be encapsulated by tissue (which alters the deliverable and detectable voltages to and from the tissue). In some examples, IMD 200 may regenerate the calibration growth curve in response to triggers such as frequent user adjustments to stimulation parameter values ​​during treatment, recognition of diminished treatment efficacy, and / or receiving a user request for recalibration.

[0106] The IMD 200 can also perform periodic pulse sweeps at different parameter values ​​to determine the patient's current growth curve and associated current postural state. These periodic sweeps can be programmed to occur at predetermined intervals, such as intervals ranging from about 1 second to about 1 hour, from about 5 seconds to about 10 minutes, or from about 10 seconds to about 1 minute. In some examples, the intervals can be varied based on the patient's activity. For example, if different postural states are detected more frequently, the IMD 200 can shorten the intervals. Conversely, if the same postural state is detected within several consecutive sweeps, the IMD 200 can lengthen the intervals. The IMD 200 can also use different intervals during different time periods of the day. For example, the IMD 200 can use longer intervals between sweeps during periods when the patient was historically sleeping and shorter intervals between sweeps during periods when the patient was historically active.

[0107] Figure 7 This is a flowchart illustrating an exemplary technique for determining a patient's postural state and controlling treatment based on that postural state, according to one or more techniques of this disclosure. For convenience, refer to... Figure 2 IMD 200 pairs Figure 7 To describe. However, Figure 7 The technology can be performed by different components of the IMD 200 or by additional or optional medical devices. Figure 7 The description will use control pulses to trigger a detectable ECAP signal, wherein the control pulses may be therapeutic or non-therapeutic to the patient. For example, the IMD 200 may use the detected ECAP signal to determine a postural state and then determine one or more parameters of the control pulses based on that postural state. The IMD 200 may also, or alternatively, determine one or more parameters of a set of notification pulses, one or more parameters of other pulses that do not trigger an ECAP, or any combination thereof. Although the processing circuitry system 210 will be described as performing... Figure 7 Many of the technologies in the technology, but in other examples, other components and / or other devices of the IMD 200 may perform some or all of the technologies.

[0108] exist Figure 7 In an exemplary operation, processing circuitry 210 controls stimulation circuitry 202 to deliver treatment to the patient (702). Treatment may involve delivering stimulation pulses configured to facilitate treatment for the patient. Processing circuitry 210 may then determine whether the patient's postural state should be detected (704). If processing circuitry 210 does not have instructions for detecting the patient's postural state (the "No" branch of block 704), processing circuitry 210 may maintain stimulation treatment (706) and continue delivering treatment to the patient (702). If processing circuitry 210 does have instructions for detecting the patient's postural state (the "Yes" branch of block 704), processing circuitry 210 controls stimulation circuitry 202 to deliver a first stimulation pulse (e.g., a control pulse) as part of a frequency sweep of pulses with different parameter values ​​(708). Processing circuitry 210 controls sensing circuitry 206 to detect an ECAP signal triggered by the stimulation pulse (710). If more stimulation pulses for the sweep are available to be delivered (the "Yes" branch of box 712), the processing circuitry 210 selects the next stimulation parameter value (e.g., the next amplitude) for the next stimulation pulse of the sweep (714) and controls the stimulation circuitry 202 to deliver the next stimulation pulse of the sweep (708). The sweep of stimulation pulses may include at least two pulses, four or more pulses, or six or more pulses. While more pulses may achieve a more accurate relationship, as few pulses as possible can be used to reduce the amount of time required to deliver the sweep pulses and sense the resulting ECAP signal.

[0109] If no further stimulation pulses for the sweep are available to be delivered (the "No" branch of box 712), the processing circuitry 210 analyzes the detected ECAP signals from the sweep and determines growth curves (716) for these detected ECAP signals. The analysis of the detected ECAP signals may include determining at least one eigenvalue for each ECAP signal (e.g., amplitude between N1-P2 peaks, area under N1 and / or P2 peaks, or other metric) and then correlating that eigenvalue with at least one parameter value of the stimulation pulse that elicits the eigenvalue. All eigenvalues ​​and associated parameter values ​​are plotted, and the processing circuitry 210 may determine a best-fit line for the points and determine the slope of that best-fit line. In other examples, the processing circuitry 210 may determine a relationship between the ECAP eigenvalues ​​and the corresponding parameter values ​​that differs from the growth curve.

[0110] Then, the processing circuitry system 210 can determine the patient's current postural state based on the determined growth curve (718). For example, the processing circuitry system 210 can compare the determined growth curve with multiple stored calibration growth curves and select the closest matching calibration growth curve. The processing circuitry system 210 can select the postural state associated with the closest matching calibration growth curve. Then, the processing circuitry system 210 selects one or more parameter values ​​(702) that define the stimulation pulses to be delivered to the patient for stimulation therapy. For example, the processing circuitry system 210 can select parameter values ​​or a set of parameter values ​​from memory or a treatment program stored for the selected postural state. Then, the processing circuitry system 210 controls the stimulation circuitry system 202 to deliver therapy according to the newly selected parameter values ​​(702).

[0111] In other examples, the processing circuitry 210 may modulate the stimulation therapy in different ways using a patient's defined postural state. For example, the postural state may be associated with a corresponding target ECAP characteristic value employed by the processing circuitry 210 to adjust one or more stimulation parameter values. The processing circuitry 210 may periodically sense the ECAP signal during the delivery of pulses configured to facilitate a therapeutic effect on the patient. The ECAP signal may be generated by pulses configured to provide a therapeutic effect (e.g., notification pulses) or pulses configured to trigger a detectable ECAP signal (e.g., control pulses) that may or may not facilitate a therapeutic effect. In either case, if the characteristic value of the detected ECAP signal is greater than the target ECAP characteristic value for that postural state (or above the upper limit of a threshold window associated with the target ECAP characteristic value), the processing circuitry 210 may reduce the amplitude of the next stimulation pulse (or some parameter value affecting the pulse intensity). If the characteristic value of the detected ECAP signal is less than the target ECAP characteristic value for the posture state (or below the lower limit of the threshold window associated with the target ECAP characteristic value), the processing circuit system 210 may increase the amplitude of the next stimulus pulse (or some parameter values ​​that affect the pulse intensity). Figure 8 The example describes this technique for modulating parameter values.

[0112] Figure 8 This is a diagram illustrating an exemplary technique for adjusting stimulation therapy. (e.g.) Figure 8As illustrated in the example, a system (such as IMD 200 or any other device or system described herein) can dynamically adjust the parameter values ​​defining the stimulation pulses based on gain values ​​that represent the patient's sensitivity to stimulation. Since the patient's sensitivity to stimulation depends on postural state, IMD 200 can use the detected postural state from the ECAP signal to adjust the gain value for the patient's sensitivity at any given time. The processing circuitry system 214 of IMD 200 controls the stimulation circuitry system 202 to deliver stimulation pulses to the patient (e.g., control pulses from which the ECAP signal can be detected and which can contribute to a therapeutic effect). The processing circuitry system 202 then controls the sensing circuitry system 206 to sense the ECAP signal triggered by the control pulses and then identify characteristic values ​​of the ECAP signal (e.g., the amplitude of the ECAP signal). The processing circuitry system 210 then determines parameter values ​​(e.g., amplitude, pulse width value, pulse frequency value, and / or oscillation rate value) that at least partially define another control pulse and / or notification pulse (not shown) based on the characteristics of the ECAP signal and the gain value (e.g., selected according to the detected postural state). Then, the processing circuit system 210 can control the stimulation circuit system 202 to deliver the next control pulse according to the determined parameter values.

[0113] like Figure 8As shown, control pulse 812 is delivered to the patient via electrode assembly 814, shown as three electrodes, representing a protective cathode. Control pulse 812 can be configured to promote a therapeutic effect on the patient. The resulting ECAP signal is sensed by two electrodes at opposite ends of the leads of electrode assembly 816 fed to differential amplifier 818. For each sensed ECAP signal, processing circuitry 210 can measure the amplitude of a portion of the ECAP signal, such as the N1-P2 voltage amplitude from a portion of the ECAP signal. This amplitude of the ECAP signal can be a characteristic value of the ECAP signal. Processing circuitry 210 can average the most recently measured ECAP amplitudes 820 (such as averaging the most recent and consecutive, 2, 3, 5, 6, or more ECAP amplitudes). In some examples, the average can be the mean or median. In some examples, if the amplitude value is determined to be erroneous, one or more ECAP amplitudes can be ignored from the calculation. The measured amplitude (or averaged measured amplitude) is then subtracted from the selected target ECAP amplitude 808 to generate a differential amplitude. The selected target ECAP amplitude 808 can be determined from the ECAP sensed when the physician or patient initially detects effective treatment from the notification pulse. This target ECAP amplitude 808 can essentially represent a reference distance between the stimulating electrode and the target neuron (e.g., the spinal cord in the case of SCS). In some examples, the processing circuitry system 210 can select the target ECAP amplitude 808 associated with the detected postural state 802 to the degree to which the target ECAP amplitude will change for different postural states.

[0114] The differential amplitude is then multiplied by a gain value for the patient to generate a preliminary differential value 810. This preliminary differential value is added to the ECAP pulse amplitude 806 (e.g., the control pulse amplitude) to generate a new or adjusted ECAP pulse amplitude that at least partially defines the next control pulse 812. The processing circuitry 210 can determine the gain value based on the detected posture state. As discussed herein, the processing circuitry 210 can detect the current posture state 802 by determining the relationship between ECAP characteristic values ​​and parameter values ​​of the pulses that elicit those ECAP characteristic values ​​(e.g., during a frequency sweep of pulses with different parameter values). For example, the processing circuitry 210 can compare a determined growth curve with a calibrated growth curve and select the posture state associated with the calibrated growth curve that best fits the determined growth curve. The processing circuitry 210 can then select a calibrated growth curve 804 from the selected posture state and use the slope of the calibrated growth curve 804 as the multiplied gain value for step 810. In other examples, instead of determining the patient's posture during the detection of the ECAP signal, or otherwise, the processing circuitry 210 directly uses the slope of the determined growth curve as the gain value.

[0115] In some examples, when the notification pulse does not trigger a detectable ECAP signal, the processing circuitry system 210 may adjust the notification pulse in addition to the control pulse. For example, to adjust the amplitude of the notification pulse, the differential value generated after doubling by a gain value 810 is multiplied by a scaling factor to generate a treatment differential value. For example, the scaling factor may be the ratio of the amplitude of a previously delivered notification pulse to the amplitude of a previously delivered control pulse 806. The treatment differential value is then added to the amplitude of the previously delivered notification pulse to generate a new or adjusted notification pulse amplitude that at least partially defines the next notification pulse. This process can be applied to notification pulses from multiple stimulation procedures. For example, if notification pulses from two different stimulation procedures are delivered as part of stimulation therapy, the system may multiply the corresponding scaling factor by the differential value to obtain the corresponding treatment differential value for the notification pulse for each stimulation procedure. Then, in other examples, the next notification pulse (or the pulse in cases where multiple stimulation procedures are involved in the treatment) is delivered to the patient via electrode combination 814 or a set of different electrodes interleaved with the control pulse 812. In some examples, at least two control pulses may be delivered between consecutive notification pulses, and at least two corresponding ECAP signals may be sensed. This increased control pulse frequency allows the system to rapidly adjust the amplitude of the notification pulses in response to any changes in the distance between the electrode and the neuron.

[0116] although Figure 8 The technique is described as being used to adjust the amplitude of the control pulse; however, in other examples, other parameter values ​​may also be changed. For example, the sensed ECAP signal can be used to increase or decrease the pulse width of the control pulse to adjust the amount of charge delivered to the tissue to maintain a consistent volume of neural activation. In other examples, the electrode combination can be adjusted to deliver different amounts of charge and to modify the number of neurons recruited by each notification pulse. In other examples, the processing circuitry system 210 may be configured to adjust the slew rate of the control pulse (i.e., the rate of change of voltage and / or amplitude at the beginning and / or end of the pulse or each phase of the pulse) in response to characteristics of the ECAP signal, such as the amplitude in the most recent ECAP amplitude.

[0117] This document describes the following embodiments. Embodiment 1: A system comprising: a stimulation circuit system configured to deliver electrical stimulation; a sensing circuit system configured to sense a plurality of evoked compound action potential (ECAP) signals; and a processing circuit system configured to: control the stimulation circuit system to deliver a plurality of electrical stimulation pulses with different amplitude values; control the sensing circuit system to detect a corresponding ECAP signal among the plurality of ECAP signals after each of the plurality of electrical stimulation pulses is delivered; and determine the patient's postural state based on the plurality of ECAP signals.

[0118] Example 2: According to the system described in Example 1, the processing circuitry is configured to: determine characteristic values ​​of the plurality of ECAP signals, each of the plurality of ECAP signals being associated with a corresponding characteristic value among the characteristic values; determine a growth curve representing the relationship between the characteristic value of the plurality of ECAP signals and the different amplitude values ​​of the plurality of electrical stimulation pulses from which the ECAP signals were induced; compare the growth curve with a plurality of calibrated growth curves associated with a corresponding postural state among the plurality of postural states; and determine the postural state of the patient based on the comparison.

[0119] Example 3: According to the system described in Example 2, the processing circuitry is configured for each of the plurality of postural states: controlling the stimulation circuitry to deliver a plurality of calibration electrical stimulation pulses with different amplitude values ​​when the patient presents the postural state; controlling the sensing circuitry to detect a corresponding calibration ECAP signal among a plurality of calibration ECAP signals after each of the plurality of calibration electrical stimulation pulses is delivered; determining calibration feature values ​​of the plurality of calibration ECAP signals, each of the plurality of calibration ECAP signals being associated with a corresponding feature value among the calibration feature values; and determining a corresponding calibration growth curve among the plurality of calibration growth curves representing the relationship between the calibration feature value of the plurality of calibration ECAP signals and the different amplitude values ​​of the plurality of calibration electrical stimulation pulses that induced the calibration ECAP signals therefrom.

[0120] Example 4: The system according to any one of Examples 1 to 3, wherein the processing circuit system is configured to control the stimulation circuit system to deliver the plurality of electrical stimulation pulses as a pulse sweep including iteratively increasing amplitude values.

[0121] Example 5: A system according to any one of Examples 1 to 4, wherein the plurality of electrical stimulation pulses are a second set of electrical stimulation pulses, and the plurality of ECAP signals are a second set of ECAP signals, and wherein the processing circuit system is configured to: control the stimulation circuit system to deliver a first set of electrical stimulation pulses during a first time period, wherein a corresponding ECAP signal in the second set of ECAP signals can be detected from the first set of electrical stimulation pulses; identify a momentary movement of the patient during the first time period; in response to identifying the momentary movement, terminate the first time period and the delivery of the first set of electrical stimulation pulses and discard the second set of ECAP signals; determine that the momentary movement has ended; and after the momentary movement has ended, control the stimulation circuit system to deliver the second set of electrical stimulation pulses and control the sensing circuit system to detect the second set of ECAP signals.

[0122] Example 6: According to the system described in Example 5, the processing circuit system is configured to, in response to determining that the instantaneous movement has ended, control the stimulation circuit system to deliver the second set of electrical stimulation pulses and control the sensing circuit system to detect the second set of ECAP signals.

[0123] Example 7: The system according to any one of Examples 5 or 6, wherein the processor is configured to detect the instantaneous movement from the electromyography signal.

[0124] Example 8: The system according to any one of Examples 5 to 7, wherein the processing circuitry is configured to detect the instantaneous movement by information received from one or more accelerometers.

[0125] Example 9: The system according to any one of Examples 1 to 8, wherein the patient's postural state includes at least one of the patient's static posture or the patient's activity level.

[0126] Example 10: According to any one of Examples 1 to 9, the processing circuit system is configured to determine the posture state by selecting the posture state from a plurality of posture states, the plurality of posture states including at least two of prone, supine, sitting and standing positions.

[0127] Example 11: The system according to any one of Examples 1 to 10, wherein the different amplitude values ​​are below the patient's discomfort threshold.

[0128] Example 12: A system according to any one of Examples 1 to 11, wherein the processing circuitry is configured to adjust the values ​​of one or more parameters that at least partially define the electrical stimulation treatment of the patient based on the determined postural state.

[0129] Example 13: The system according to any one of Examples 1 to 12, wherein the implantable medical device includes the stimulation circuit system, the sensing circuit system and the processing circuit system.

[0130] Example 14: A method comprising: controlling a stimulation circuit system to deliver a plurality of electrical stimulation pulses with different amplitude values ​​by the processing circuit system; controlling a sensing circuit system to detect a corresponding ECAP signal among a plurality of evoked compound action potential (ECAP) signals after each of the plurality of electrical stimulation pulses is delivered by the processing circuit system; and determining the patient's postural state by the processing circuit system and based on the plurality of ECAP signals.

[0131] Example 15: According to the method of Example 14, the method further includes: determining characteristic values ​​of the plurality of ECAP signals, each of the plurality of ECAP signals being associated with a corresponding characteristic value of the characteristic values; determining a growth curve representing the relationship between the characteristic values ​​of the plurality of ECAP signals and the different amplitude values ​​of the plurality of electrical stimulation pulses from which the ECAP signals were induced; comparing the growth curve with a plurality of calibrated growth curves associated with a corresponding postural state among the plurality of postural states; and determining the postural state of the patient based on the comparison.

[0132] Example 16: According to the method of Example 15, the method further includes, for each of the plurality of postural states: controlling the stimulation circuitry system to deliver a plurality of calibration electrical stimulation pulses with different amplitude values ​​when the patient presents the postural state; controlling the sensing circuitry system to detect a corresponding calibration ECAP signal among a plurality of calibration ECAP signals after each of the plurality of calibration electrical stimulation pulses is delivered; determining calibration feature values ​​of the plurality of calibration ECAP signals, each of the plurality of calibration ECAP signals being associated with a corresponding feature value among the calibration feature values; and determining a corresponding calibration growth curve among the plurality of calibration growth curves representing the relationship between the calibration feature value of the plurality of calibration ECAP signals and the different amplitude values ​​of the plurality of calibration electrical stimulation pulses that induced the calibration ECAP signals therefrom.

[0133] Example 17: The method according to any one of Examples 14 to 16, wherein controlling the stimulation circuit system to deliver the plurality of electrical stimulation pulses includes controlling the stimulation circuit system to provide a pulse sweep frequency including iteratively increasing amplitude values.

[0134] Example 18: The method according to any one of Examples 14 to 16, wherein the plurality of electrical stimulation pulses is a second set of electrical stimulation pulses, and the plurality of ECAP signals is a second set of ECAP signals, and wherein the method further comprises: controlling the stimulation circuit system to deliver a first set of electrical stimulation pulses during a first time period, wherein a corresponding ECAP signal in the second set of ECAP signals can be detected from the first set of electrical stimulation pulses; identifying a momentary movement of the patient during the first time period; terminating the first time period and the delivery of the first set of electrical stimulation pulses and discarding the second set of ECAP signals in response to identifying the momentary movement; determining that the momentary movement has ended; and after the momentary movement has ended, controlling the stimulation circuit system to deliver the second set of electrical stimulation pulses and controlling the sensing circuit system to detect the second set of ECAP signals.

[0135] Example 19: According to the method of Example 18, the method further includes, in response to determining that the instantaneous movement has ended, controlling the stimulation circuit system to deliver the second set of electrical stimulation pulses and controlling the sensing circuit system to detect the second set of ECAP signals.

[0136] Example 20: The method according to any one of Examples 18 and 19, further comprising detecting the instantaneous movement from the electromyographic signal.

[0137] Example 21: The method according to any one of Examples 18 to 20, the method further includes detecting the instantaneous movement by information received from one or more accelerometers.

[0138] Example 22: The method according to any one of Examples 14 to 21, wherein the patient's postural state includes at least one of the patient's static posture or the patient's activity level.

[0139] Example 23: The method according to any one of Examples 14 to 22, wherein determining the posture state includes selecting the posture state from a plurality of posture states to determine the posture state, the plurality of posture states including at least two of prone, supine, sitting and standing positions.

[0140] Example 24: The method according to any one of Examples 14 to 23, wherein the different amplitude values ​​are below the patient's discomfort threshold.

[0141] Example 25: The method according to any one of Examples 14 to 24, further comprising adjusting the values ​​of one or more parameters that at least partially define the electrical stimulation treatment of the patient based on the determined postural state.

[0142] Example 26: A computer-readable medium comprising instructions that, when executed, cause a processing circuitry system to: control a stimulation circuitry system to deliver a plurality of electrical stimulation pulses having different amplitude values; control a sensing circuitry system to detect a corresponding ECAP signal among a plurality of evoked compound action potential (ECAP) signals after each of the plurality of electrical stimulation pulses is delivered; and determine the patient's postural state based on the plurality of ECAP signals.

[0143] The techniques described in this disclosure can be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, aspects of the techniques can be implemented within one or more processors or processing circuitry systems, including one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry system, and any combination of such components. The terms "processor" or "processing circuitry system" can generally refer to any of the aforementioned logic circuitry systems, alone or in combination with other logic circuitry systems, or any other equivalent circuitry system. A control unit, including hardware, can also perform one or more of the techniques disclosed herein.

[0144] Such hardware, software, and firmware may be implemented within the same device or in separate devices to support the various operations and functions described in this disclosure. Furthermore, any described unit, circuit, or component may be implemented together or individually as discrete but interoperable logic devices. Describing different features as circuits or units is intended to highlight different functional aspects and does not necessarily imply that such circuits or units must be implemented by separate hardware or software components. Rather, the functionality associated with one or more circuits or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components.

[0145] The techniques described in this disclosure can also be embodied or encoded in a computer-readable medium (such as a computer-readable storage medium) containing instructions, which can be described as a non-transitory medium. Instructions embedded or encoded in a computer-readable storage medium can cause a programmable processor or other processor to perform the method, for example, when executing those instructions. Computer-readable storage media may include random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, hard disk, CD-ROM, floppy disk, magnetic tape cassette, magnetic media, optical media, or other computer-readable media.

Claims

1. A system comprising: A stimulation circuit system configured to deliver electrical stimulation; A sensing circuit system configured to sense multiple evoked composite action potential (ECAP) signals; and Processing circuitry system, the processing circuitry system being configured to: The stimulation circuit system is controlled to deliver multiple electrical stimulation pulses with different amplitude values; The sensing circuit system is controlled to detect the corresponding ECAP signal among the plurality of ECAP signals after each of the plurality of electrical stimulation pulses is delivered; as well as The patient's posture is determined based on the multiple ECAP signals.

2. The system of claim 1, wherein the processing circuitry is configured as follows: Determine the feature values ​​of the plurality of ECAP signals, wherein each of the plurality of ECAP signals is associated with a corresponding feature value among the feature values; A growth curve is determined that represents the relationship between the characteristic values ​​of the plurality of ECAP signals and the different amplitude values ​​of the plurality of electrical stimulation pulses from which the ECAP signals were induced; The growth curve is compared with multiple calibrated growth curves associated with corresponding pose states in the same plurality of pose states; and The patient's postural state is determined based on the comparison.

3. The system of claim 2, wherein the processing circuitry is configured for each of the plurality of pose states: The stimulation circuitry system is controlled to deliver multiple calibrated electrical stimulation pulses with different amplitude values ​​when the patient assumes the posture. The sensing circuit system is controlled to detect the corresponding calibration ECAP signal among a plurality of calibration ECAP signals after each calibration electrical stimulation pulse is delivered from the plurality of calibration electrical stimulation pulses; Determine calibration feature values ​​for the plurality of calibration ECAP signals, wherein each calibration ECAP signal is associated with a corresponding feature value among the calibration feature values; as well as Determine the corresponding calibration growth curve among the plurality of calibration growth curves, representing the relationship between the calibration characteristic values ​​of the plurality of calibration ECAP signals and the different amplitude values ​​of the plurality of calibration electrical stimulation pulses that induced the calibration ECAP signals therefrom.

4. The system of claim 1, wherein the processing circuitry is configured to control the stimulation circuitry to deliver the plurality of electrical stimulation pulses as a pulse sweep comprising iteratively increasing amplitude values.

5. The system of claim 1, wherein the plurality of electrical stimulation pulses are a second set of electrical stimulation pulses, and the plurality of ECAP signals are a second set of ECAP signals, and wherein the processing circuitry is configured to: During the first time period, the stimulation circuit system is controlled to deliver a first set of electrical stimulation pulses, and the corresponding ECAP signal in the second set of ECAP signals can be detected from the first set of electrical stimulation pulses. Identify the patient's instantaneous movement during the first time period; In response to recognizing the instantaneous movement, the delivery of the first time period and the first set of electrical stimulation pulses is terminated and the second set of ECAP signals is discarded; It has been determined that the instantaneous movement has ended; as well as After the instantaneous movement has ended, the stimulation circuit system is controlled to deliver the second set of electrical stimulation pulses and the sensing circuit system is controlled to detect the second set of ECAP signals.

6. The system of claim 5, wherein the processing circuitry is configured to, in response to determining that the instantaneous movement has ended, control the stimulation circuitry to deliver the second set of electrical stimulation pulses and control the sensing circuitry to detect the second set of ECAP signals.

7. The system of claim 5, wherein the processing circuitry is configured to detect the instantaneous movement from the electromyography signal.

8. The system of claim 5, wherein the processing circuitry is configured to detect the instantaneous movement by information received from one or more accelerometers.

9. The system of claim 1, wherein the patient's postural state includes at least one of the patient's static posture or the patient's activity level.

10. The system of claim 1, wherein the processing circuitry is configured to determine the posture state by selecting the posture state from a plurality of posture states, the plurality of posture states including at least two of prone, supine, sitting, and standing positions.

11. The system of claim 1, wherein the different amplitude values ​​are below the patient's discomfort threshold.

12. The system of claim 1, wherein the processing circuitry is configured to adjust the values ​​of one or more parameters that at least partially define the electrical stimulation treatment of the patient based on the determined postural state.

13. The system of claim 1, wherein the implantable medical device comprises the stimulation circuit system, the sensing circuit system, and the processing circuit system.

14. An implantable medical device, comprising: Processing circuit system; A storage device storing instructions, which, when executed, cause the processing circuitry system to perform a method comprising: The processing circuit system controls the stimulation circuit system to deliver multiple electrical stimulation pulses with different amplitude values; The processing circuit system controls the sensing circuit system to detect the corresponding ECAP signal among the plurality of evoked compound action potential (ECAP) signals after each of the plurality of electrical stimulation pulses is delivered; and The patient's posture is determined by the processing circuitry system based on the multiple ECAP signals.

15. The implantable medical device according to claim 14, further comprising: Determine the feature values ​​of the plurality of ECAP signals, wherein each of the plurality of ECAP signals is associated with a corresponding feature value among the feature values; A growth curve is determined that represents the relationship between the characteristic values ​​of the plurality of ECAP signals and the different amplitude values ​​of the plurality of electrical stimulation pulses from which the ECAP signals were induced; The growth curve is compared with multiple calibrated growth curves associated with the corresponding posture states in the same multiple posture states; as well as The patient's postural state is determined based on the comparison.

16. The implantable medical device of claim 15, the method further comprising, for each of the plurality of posture states: The stimulation circuitry system is controlled to deliver multiple calibrated electrical stimulation pulses with different amplitude values ​​when the patient assumes the posture. The sensing circuit system is controlled to detect the corresponding calibration ECAP signal among a plurality of calibration ECAP signals after each calibration electrical stimulation pulse is delivered from the plurality of calibration electrical stimulation pulses; Determine calibration feature values ​​for the plurality of calibration ECAP signals, wherein each calibration ECAP signal is associated with a corresponding feature value among the calibration feature values; as well as Determine the corresponding calibration growth curve among the plurality of calibration growth curves, representing the relationship between the calibration characteristic values ​​of the plurality of calibration ECAP signals and the different amplitude values ​​of the plurality of calibration electrical stimulation pulses that induced the calibration ECAP signals therefrom.

17. The implantable medical device of claim 14, wherein controlling the stimulation circuit system to deliver the plurality of electrical stimulation pulses comprises controlling the stimulation circuit system to provide a pulse sweep frequency comprising iteratively increasing amplitude values.

18. The implantable medical device of claim 14, wherein the plurality of electrical stimulation pulses are a second set of electrical stimulation pulses, and the plurality of ECAP signals are a second set of ECAP signals, and wherein the method further comprises: During the first time period, the stimulation circuit system is controlled to deliver a first set of electrical stimulation pulses, and the corresponding ECAP signal in the second set of ECAP signals can be detected from the first set of electrical stimulation pulses. Identify the patient's instantaneous movement during the first time period; In response to recognizing the instantaneous movement, the delivery of the first time period and the first set of electrical stimulation pulses is terminated and the second set of ECAP signals is discarded; It has been determined that the instantaneous movement has ended; as well as After the instantaneous movement has ended, the stimulation circuit system is controlled to deliver the second set of electrical stimulation pulses and the sensing circuit system is controlled to detect the second set of ECAP signals.

19. The implantable medical device of claim 18, the method further comprising, in response to determining that the transient movement has ended, controlling the stimulation circuitry system to deliver the second set of electrical stimulation pulses and controlling the sensing circuitry system to detect the second set of ECAP signals.

20. The implantable medical device of claim 18, the method further comprising detecting the instantaneous movement from an electromyographic signal.

21. The implantable medical device of claim 18, the method further comprising detecting the instantaneous movement by information received from one or more accelerometers.

22. The implantable medical device of claim 14, wherein the patient's postural state includes at least one of the patient's static posture or the patient's activity level.

23. The implantable medical device of claim 14, wherein determining the posture state comprises selecting the posture state from a plurality of posture states to determine the posture state, the plurality of posture states including at least two of prone, supine, sitting, and standing positions.

24. The implantable medical device of claim 14, wherein the different amplitude values ​​are below the patient's discomfort threshold.

25. The implantable medical device of claim 14, the method further comprising adjusting the values ​​of one or more parameters that at least partially define the electrical stimulation treatment of the patient based on the determined postural state.

26. A computer-readable medium comprising instructions that, when executed, cause a processing circuit system to: The stimulation circuitry system delivers multiple electrical stimulation pulses with different amplitude values. The control sensing circuitry system detects the corresponding ECAP signal from a plurality of evoked compound action potential (ECAP) signals after each of the plurality of electrical stimulation pulses is delivered; and The patient's posture is determined based on the multiple ECAP signals.

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