Controlling electrical stimulation by medical device

Abstract

A system includes processing circuitry configured to: receive a first signal via sensing circuitry of the system, the first signal representing a first evoked electrical signal induced by an electrical stimulation delivered during a posture state of a patient; determining a first signal characteristic of the first evoked electrical signal; receiving a patient input via one or more user devices of the system, the patient input indicating a comfort level of the patient associated with the first evoked electrical signal; determining a target characteristic of the posture state based on the first signal characteristic and the patient input; receiving a second signal via the sensing circuit, the second signal representing a second evoked electrical signal induced by the electrical stimulation delivered during the gestural state; and control one or more parameters based on a second signal characteristic of the second evoked electrical signal and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation.

Description

[0001] This application claims priority to U.S. Provisional Patent Application 63 / 499,059, filed April 28, 2023, the entirety of which is incorporated by reference herein. TECHNICAL FIELD

[0002] The present disclosure relates generally to electrical stimulation therapy, and more particularly to control of electrical stimulation therapy. BACKGROUND

[0003] 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 that include electrodes positioned proximate to a target location associated with the patient’s brain, spinal cord, pelvic nerve, peripheral nerve, or gastrointestinal tract. Stimulation proximate to the spinal cord, proximate to the sacral nerve, within the brain, and proximate to peripheral nerves are commonly referred to as spinal cord stimulation (SCS), sacral neuromodulation (SNM), deep brain stimulation (DBS), and peripheral nerve stimulation (PNS), respectively. SUMMARY

[0004] Generally, the present disclosure relates to devices, systems, and techniques for controlling electrical stimulation therapy based at least in part on evoked signals (e.g., evoked compound action potentials (ECAPs)) elicited by electrical stimulation signals in a posture state of a patient.

[0005] A medical device (e.g., an implantable medical device) can deliver one or more electrical stimulation signals to a patient via one or more leads, and the medical device can sense ECAPs elicited by the electrical stimulation signals. The medical device can receive patient input indicating a posture of the patient and / or a level of pain perceived by the patient in the patient’s body. In some examples, the medical device can determine a posture of the patient based on sensor data of one or more sensors coupled with processing circuitry of the medical device, and associate patient input indicating a level of pain or other patient-perceived feedback with the detected posture state.

[0006] The medical device can be configured to compare a currently sensed evoked signal to a previous evoked signal and corresponding patient input for the same posture state when the patient is in the same posture state. Based on the comparison between the current evoked signal and the previous evoked signal, the medical device can adjust stimulation parameters of the electrical stimulation signal to optimize treatment of perceived pain or discomfort the patient can experience in the posture state and other posture states. In some examples, the medical device can compare evoked signals to perform different functions, including but not limited to: detecting damage and / or displacement of an electrical lead coupled to the medical device and configured to deliver the electrical stimulation signal, determining a change in a disease state of the patient, determining an effect of one or more medications or therapeutic substances on the patient, or any combination thereof.

[0007] In some examples, the disclosure describes a system comprising: processing circuitry configured to: receive, via sensing circuitry of the system, a first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determine a first signal characteristic of the one or more first evoked electrical signals for the posture state; receive, via one or more user devices of the system, patient input indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determine, based on the first signal characteristic and the patient input, a target characteristic for the posture state; receive, via the sensing circuitry, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and control one or more parameters based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation to the patient during the posture state.

[0008] In some examples, the disclosure describes a method comprising: receiving, by processing circuitry of a medical device system, via sensing circuitry of the medical device system, a first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determining, by the processing circuitry, a first signal characteristic of the one or more first evoked electrical signals for the posture state; receiving, by the processing circuitry, patient input from one or more user devices indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determining, by the processing circuitry, a target characteristic for the posture based on the first signal characteristic and the patient input; receiving, by the processing circuitry via the sensing circuitry, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and controlling, by the processing circuitry, one or more parameters defining at least in part subsequent delivery of the electrical stimulation to the patient during the posture state based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic.

[0009] In some examples, the disclosure describes a computer-readable medium comprising instructions that, when executed, cause processing circuitry of an implantable medical device system to perform a method comprising: receiving, by processing circuitry of a medical device system, via sensing circuitry of the medical device system, a first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determining, by the processing circuitry, a first signal characteristic of the one or more first evoked electrical signals for the posture state; receiving, by the processing circuitry, patient input from one or more user devices indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determining, by the processing circuitry, a target characteristic for the posture based on the first signal characteristic and the patient input; receiving, by the processing circuitry via the sensing circuitry, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and controlling, by the processing circuitry, one or more parameters defining at least in part subsequent delivery of the electrical stimulation to the patient during the posture state based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic.

[0010] This 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, devices, and methods described in detail within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and in the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a conceptual diagram illustrating an example system including an implantable medical device (IMD) configured to deliver stimulation therapy to a patient and an external programmer, in accordance with one or more techniques of this disclosure.

[0012] Figure 2 is a block diagram illustrating an example configuration of components of an IMD of Figure 1

[0013] Figure 3 is a block diagram illustrating an example configuration of components of an external programmer of Figure 1

[0014] Figure 4 is a plot illustrating example evoked compound action potentials (ECAPs) sensed for respective stimulation pulses, in accordance with one or more techniques of this disclosure.

[0015] Figure 5 is an example timing diagram illustrating examples of an electrical stimulation pulse, a respective stimulation pulse, and a respective sensed ECAP, in accordance with one or more techniques of this disclosure.

[0016] Figure 6A is a conceptual diagram illustrating a spine of a patient implanted with an electrical lead in a first posture state, in accordance with one or more techniques of this disclosure.

[0017] Figure 6B is a conceptual diagram illustrating a spine of Figure 6A in a second posture state, in accordance with one or more techniques of this disclosure.

[0018] Figure 7 is a flow diagram illustrating an example process for delivering stimulation therapy to a patient based on a sensed evoked signal and a posture state of the patient, in accordance with one or more techniques of this disclosure.

[0019] Figure 8 is a flow diagram illustrating an example process for controlling stimulation therapy based on a sensed evoked signal and a posture state of the patient, in accordance with one or more techniques of this disclosure.

[0020] Figure 9 ​​is a flowchart illustrating an example process for determining damage and / or displacement of an electrical lead within a patient's body based on a sensed evoked signal and a patient posture state in accordance with one or more techniques of the present disclosure.

[0021] Throughout the specification and drawings like reference numerals refer to like elements. DETAILED DESCRIPTION

[0022] The present disclosure describes example medical devices, systems, and techniques for controlling electrical stimulation therapy delivered to a patient based, at least in part, on an evoked electrical signal (e.g., an evoked compound action potential (ECAP)) sensed or detected by the medical device in a determined patient posture state. The electrical stimulation therapy is typically delivered by the medical device to a target tissue (e.g., one or more nerves or muscles) of the patient 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 a clinician, the patient, and / or the medical device to alleviate various symptoms, such as pain, muscle disorders, etc.

[0023] An ECAP is a measure of neural recruitment because each ECAP signal represents a superposition of potentials generated in response to the firing of axons in response to an electrical stimulation (e.g., a stimulation pulse). Changes in characteristics of the ECAP signal (e.g., amplitude of a portion of the signal, area under one or more peaks, frequency content, and / or maximum peak timing and / or minimum peak timing) occur depending on how many axons are activated by the delivered stimulation pulse. The system can monitor changes in the characteristics of the ECAP signal and use the changes in the characteristics to adjust one or more stimulation parameters that at least partially define the stimulation pulses delivered to the patient. For example, the system can decrease the intensity of the stimulation pulses (e.g., decrease the current amplitude and / or pulse width) in response to detecting an increase in the amplitude of the ECAP signal. The ECAP can vary based on the posture state of the patient. In some examples, changes in the ECAP signal can be due to changes in the posture state of the patient, and changes in the ECAP signal alone can not be sufficient to determine that parameters of the electrical stimulation therapy need to be adjusted. Furthermore, it can be difficult to track disease progression or changes in patient therapy over time by monitoring the ECAP signal alone.

[0024] In some examples, the medical device can deliver stimulation pulses in the form of control pulses and notification pulses. More specifically, the electrical stimulation pulses are delivered in the form of notification pulses and control pulses that at least partially interleave with each other. Control pulses (e.g., stimulation signal test pulses) are those stimulation pulses configured to elicit one or both of a stimulation signal and a detectable ECAP signal. In some examples, the control pulses can contribute to therapy of the patient. In other examples, the control pulses do not contribute to therapy of the patient, e.g., non-therapeutic pulses. In this way, the control pulses can or can not be configured to elicit a therapeutic effect on the patient. Notification pulses are those stimulation pulses defined at least in part based on one or more parameters of a detectable stimulation signal elicited by one or more control pulses. In some examples, the one or more notification pulses are defined at least in part based on one or more parameters of a respective ECAP elicited by one or more control pulses. In this way, the notification pulses are “informed” by the ECAP signals detected from the control pulses. The notification pulses are also configured to provide therapy to the patient, such as providing paresthesia that alleviates a symptom of pain.

[0025] As described herein, a medical device can sense evoked signals (e.g., ECAP signals) elicited by electrical stimulation delivered to tissue of a patient when the patient is in a particular postural state (e.g., standing, sitting, squatting, lying down). The medical device can determine the postural state based on the sensed signals, and / or receive patient input identifying the current postural state. The medical device can further receive patient input (e.g., via an external programmer, or via interaction with the medical device by tapping or other means) indicating a patient comfort or discomfort associated with (e.g., related to) the sensed evoked signals. Based on the sensed evoked signals and the patient input, the medical device and / or medical device system can correspond different levels of evoked signal characteristic(s) to different levels of patient-perceived comfort. In some examples, a particular level of evoked signal characteristic that correlates to no patient-perceived discomfort can be established as a target value or target range of the evoked signal characteristic in the patient’s baseline evoked electrical signal in a particular postural state. Each postural state or each group of one or more postural states can be associated with a target value or target range of the evoked signal characteristic.

[0026] Subsequently, the medical device can sense other evoked signals in response to the electrical stimulation therapy. The medical device and / or medical device system can compare the evoked signals and adjust parameters of the electrical stimulation therapy based on a deviation of the signal characteristic(s) of the subsequently sensed evoked signals from the signal characteristic of the baseline evoked signal. The medical device can also monitor patient input of comfort levels and corresponding evoked signal characteristic values over time to adjust the target value or target range of the evoked signal characteristic value.

[0027] The techniques disclosed herein can provide one or more advantages. For example, adjusting the parameters of stimulation therapy based on sensed evoked signals of a given patient postural state can reduce the amount of patient input required to adjust the stimulation therapy and / or reduce the amount of time required to adjust the stimulation therapy, thereby simplifying the process required to alleviate patient-perceived discomfort via stimulation therapy. In some examples, adjusting parameters based on sensed evoked signals and postural state can increase the optimization of stimulation therapy delivery (e.g., optimization to a minimum effective dose), thereby reducing power consumption and increasing the operational life of the medical device. In some examples, using sensed evoked signals and postural state to control stimulation therapy can allow medical devices and / or medical device systems to avoid unnecessary adjustments to stimulation therapy due to acute discomfort perceived by the patient, thereby reducing patient discomfort, for example, due to unnecessary changes in stimulation therapy. In some examples, medical devices and / or medical device systems can use sensed evoked signals and patient postural state to detect potential damage or displacement of electrical leads coupled to the medical device, and / or determine changes in the patient's disease state, thereby improving responsiveness to the possibility of damage to the medical device.

[0028] Figure 1 This is a conceptual diagram illustrating an example system 100 including an implantable medical device (IMD) 106. While this disclosure is primarily described with reference to one IMD 106, other examples may include two or more IMDs 106. The IMD 106 may deliver electrical stimulation pulses to the tissues of a patient 102, for example, via leads 108A, 108B (collectively referred to herein as “leads 108”). The IMD 106 may be configured to sense evoked signals (e.g., ECAP) or other bioelectrical signals, sense the posture of the patient 102, deliver other medical treatments to the patient 102 (e.g., deliver therapeutic substances via a pump), and / or perform any other medical function.

[0029] like Figure 1 As shown, IMD 106 is configured to deliver spinal cord stimulation (SCS) therapy to or near the spinal cord 104 of patient 102. In some examples, multiple IMDs 106 may be configured to deliver SCS therapy and / or PNS therapy to patient 102. For example, as part of SCS therapy, one IMD may deliver a “pre-excitation” stimulation pulse to the glial cells of spinal cord 104, and another IMD 106 may deliver a “baseline” stimulation pulse to peripheral nerves to alleviate pain experienced by patient 102. In such examples, the baseline stimulation pulse may generate action potentials (e.g., ECAPs) in the peripheral nerves, which can be detected by IMD 106.

[0030] According to one or more techniques of this disclosure, the IMD 106 can be configured to communicate with an external programmer 120. While the techniques described in this disclosure are generally applicable to a wide variety of medical devices, including external devices and IMDs, for illustrative purposes, the application of such techniques 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 to other types of medical devices or other therapeutic applications of medical devices.

[0031] like Figure 1 As shown, system 100 includes an IMD 106, a lead wire 108, and an external programmer 120 shown together with a patient 102 (which is typically a human patient). Figure 1 In the examples, IMD 106 is an implantable electrical stimulator configured to generate and deliver electrical stimulation therapy to a patient 102 via one or more electrodes of leads 108A and / or 108B, for example, to relieve chronic pain or other symptoms. In some examples, IMD 106 may be coupled to a single lead 108 carrying multiple electrodes or two or more leads 108 each carrying multiple electrodes. This electrical stimulation may be delivered in the form of continuous stimulation signals or stimulation pulses. In some examples, IMD 106 may be configured to generate and deliver control pulses configured to elicit an ECAP signal, for example, to sense an ECAP signal for a given postural state. In some examples, the control pulses may or may not contribute to treatment. In some examples, in addition to control pulses, IMD 106 may also deliver notification pulses that contribute to patient treatment but do not elicit a detectable ECAP signal. IMD 106 may be a chronic electrical stimulator that remains implanted in the patient 102 for weeks, months, or even years. In other examples, IMD 106 may be a temporary or experimental stimulator used to screen or evaluate the efficacy of electrical stimulation for chronic treatment. IMD 106 may be implanted in the patient 102 or coupled to a percutaneously implanted lead (e.g., lead 108). In some examples, IMD 106 is leadless.

[0032] IMD 106 can be made of components sufficient to mount IMD 106 (e.g., Figure 2Any polymer, metal, or composite material that is housed within the patient 102 (of the illustrated components) is constructed. In this example, the IMD 106 can be constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material, such as silicone, polyurethane, or liquid crystal polymer. The IMD 106 can be surgically implanted in a location near the pelvis, abdomen, thigh, or buttocks of the patient 102. In other examples, the IMD 106 can be implanted within other suitable locations within the patient 102, which can depend on, for example, a target site within the patient 102 that requires delivery of electrical stimulation therapy (e.g., only the spinal cord 104 of the patient 102). The housing of the IMD 106 can be configured to provide a hermetic seal for components such as a rechargeable or non-rechargeable power source. Additionally, in some examples, the housing of the IMD 106 is selected from materials that facilitate receiving energy in order to charge a rechargeable power source.

[0033] For example, electrical stimulation energy, which can be pulses based on constant current or constant voltage, is delivered from the IMD 106 to one or more target tissue sites of the patient 102 via one or more electrodes (not shown) of the corresponding implantable lead 108. In examples, the electrical stimulation energy is delivered to the spinal cord 104 of the patient 102. Figure 1 In examples, each of the leads 108 carries electrodes placed near a target tissue (e.g., near the spinal cord 104). One or more electrodes can be disposed at a distal end of each of the leads 108 and / or at other locations along an intermediate point of the lead. The leads 108 can be implanted and coupled to the IMD 106. The electrodes can convey electrical stimulation generated by an electrical stimulation generator in the IMD 106 to tissue of the patient 102. Although the leads 108 can each be a single lead, the leads 108 can include lead extensions or other segments that can facilitate implantation or positioning of the leads 108. In some examples, the IMD 106 can be a leadless stimulator with one or more electrode arrays arranged on the stimulator housing rather than on a lead extending from the housing. Additionally, in some other examples, the system 100 can include one lead or more than two leads, each coupled to the IMD 106 and directed to similar or different target tissue sites.

[0034] The electrodes of the leads 108 can be electrode pads on a paddle lead, circular (e.g., ring-shaped) electrodes around a lead body, conformable electrodes, cuff electrodes, segmented electrodes (e.g., electrodes disposed at different circumferential locations on a lead rather than a continuous ring-shaped electrode), any combination thereof (e.g., ring-shaped electrodes and segmented electrodes), or any other type of electrode capable of forming monopolar, bipolar, or multipolar electrode combinations for therapy. Ring-shaped electrodes arranged at different axial locations at a distal end of the leads 108 will be described for purposes of illustration.

[0035] Electrodes are described as being deployed via lead 108 for illustrative purposes, but electrode arrays can be deployed in different ways. For example, a housing associated with a leadless stimulator can carry an electrode array, e.g., in the form of rows and / or columns (or other patterns), to which shift operations can be applied. Such electrodes can be arranged as surface electrodes, ring electrodes, or protrusions. As another option, an electrode array can be formed of rows and / or columns of electrodes on one or more paddle leads. In some examples, an electrode array includes electrode segments arranged at respective locations on a periphery of a lead, e.g., in the form of one or more segmented rings on a circumference of a cylindrical lead. In other examples, one or more leads 108 are linear leads with 8 ring electrodes along an axial length of the lead. In another example, the electrodes are segmented rings arranged in a linear fashion along an axial length of the lead and at a periphery of the lead.

[0036] Stimulus parameters of a therapy stimulation program, which define an electrical stimulation therapy delivered by IMD 106 through electrodes of lead 108, can include information identifying which electrodes have been selected for delivery of stimulation according to the stimulation program, the polarity of the selected electrodes (i.e., the electrode combination of the program), and the voltage or current amplitude, pulse frequency, pulse width, pulse shape of the stimulation delivered by the electrodes. These stimulus parameters of a stimulation pulse (e.g., a control pulse and / or an informative pulse) are typically predetermined parameter value(s) determined (e.g., set according to the stimulation program) prior to delivery of the stimulation pulse. In some examples, however, system 100 automatically changes the parameter value(s) based on one or more factors or based on patient input.

[0037] Although Figure 1 While SCS therapy is described as being directed to, e.g., the treatment of pain, 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 disorders (e.g., urinary incontinence or other bladder dysfunction, fecal incontinence, pelvic pain, intestinal dysfunction, or sexual dysfunction), obesity, gastroparesis, or psychiatric 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 stimulation therapy capable of treating a condition of patient 102.

[0038] In some examples, the leads 108 and / or the IMD 106 include one or more sensors configured to allow the IMD 106 to monitor one or more parameters of the patient 102, such as a posture state of the patient 102. The posture state can include, but is not limited to, standing, sitting, hunched, crouching, lying down, etc. When the patient 102 is in each posture state, the patient’s 102 spine and spinal cord 104 can be in different positions, and the IMD 106 can deliver electrical stimulation to different nerves and / or nerve fiber tracts of the patient 102. Different delivery locations can cause the IMD 106 to sense ECAP signals having different signal characteristics for different posture states in response to the same electrical stimulation therapy. In some examples, the IMD 106 can stimulate the same nerves and / or the same fiber tracts in different posture states. In such examples, the IMD 106 can sense ECAP signals having the same or similar signal characteristic(s) for different posture states. In some examples, the one or more sensors of the IMD 106 can sense the ECAP signals, for example, from the nerves of the patient 102.

[0039] Each of the IMDs 106 can be configured to deliver electrical stimulation therapy to the patient 105 via a selected combination of electrodes carried by one or both of the leads 108, alone or in combination with an electrode carried by or defined by the housing of the IMD 106. The target tissue of the electrical stimulation therapy can be any tissue affected by electrical stimulation, which can be in the form of electrical stimulation pulses or continuous waveforms. In some examples, the target tissue includes a nerve, smooth muscle, or skeletal muscle. In Figure 1 In the illustrated example (e.g., with respect to the IMD 106), the target tissue is tissue near the spinal cord 104, such as within the intrathecal space or epidural space of the spinal cord 104, or in some examples, an adjacent nerve branching off from the spinal cord 104. The leads 108 (e.g., leads 108A, 108B) can be introduced to the spinal cord 104 via any suitable region, such as a thoracic, cervical, or lumbar region. Stimulation of the spinal cord 104, for example, can prevent pain signals from propagating through the spinal cord 104 and to the brain of the patient 102. The patient 102 can perceive the interruption of the pain signals as a reduction in pain, and thus as an effective therapeutic outcome. In other examples, stimulation of the spinal cord 104 can produce paresthesia, which can reduce the patient’s 102 perception of pain, and thus provide an effective therapeutic outcome.

[0040] A user, such as a clinician or patient 102, can interact with a user interface of external programmer 120 to program and / or control IMD 106. Programming IMD 106 can generally refer to generating and transmitting commands, programs, or other information used to control the operation of IMD 106. In this manner, IMD 106 can receive transmitted commands and programs from external programmer 120 to control electrical stimulation therapy (e.g., informed pulses) and control stimulation (e.g., control pulses). For example, external programmer 120 can transmit therapy stimulation programs, stimulation parameter adjustments, therapy stimulation program selections, patient inputs, or other information used to control the operation of IMD 106, e.g., through wireless telemetry or a wired connection. As described herein, stimulation delivered to a patient can include control pulses, and in some examples, stimulation can include control pulses and informed pulses.

[0041] In some cases, if external programmer 120 is primarily intended for use by a physician or clinician, it can be characterized as a physician or clinician programmer. In other cases, if external programmer 120 is primarily intended for use by a patient, it can be characterized as a patient programmer. A patient programmer is generally accessible to patient 102, and in many cases, it can be a portable device that can accompany patient 102 throughout their daily routine. For example, a patient programmer can receive input from patient 102 when the patient wishes to terminate or change electrical stimulation therapy, and / or can be configured to receive patient input indicating a level of comfort or a level of discomfort associated with therapy in that patient’s state. Generally, a physician or clinician programmer can support a clinician in selecting and generating programs for use by IMD 106, while a patient programmer can support a patient in adjusting and selecting these programs during normal use. In other examples, external programmer 120 can include or be part of an external charging device that recharges a power source of IMD 106. In this manner, a user can program and charge IMD 106 using one device or multiple devices.

[0042] As described herein, information can be transmitted between external programmer 120 and IMD 106. Accordingly, IMD 106 and external programmer 120 can communicate via wireless communication using any of the techniques known in the art. Examples of communication techniques can include, for example, radiofrequency (RF) telemetry and inductive coupling, although other techniques are also contemplated. In some examples, external programmer 120 includes a communication head that can be placed proximate to the patient’s body near the IMD 106 implant site to improve the quality or security of communication between IMD 106 and external programmer 120. Communication between external programmer 120 and IMD 106 can occur during or separate from power transmission. In some examples, IMD 106 and external programmer 120 can communicate via an intermediary device (e.g., another IMD, a body harness, a wearable intermediary device such as a smartwatch or a smartphone).

[0043] In some examples, in response to a command from external programmer 120, IMD 106 delivers electrical stimulation therapy to a target tissue site within patient 102 via electrodes (not depicted) on lead 108. In some examples, IMD 106 modifies the therapy stimulation program as therapy needs of patient 102 evolve over time and / or based on changes in the sensed ECAP signal when patient 102 is in the same postural state. For example, modification of the therapy stimulation program can result in an adjustment to at least one parameter of the plurality of notification pulses. The efficacy of therapy can decrease when patient 102 receives the same therapy over an extended period of time. In some cases, the parameters of the plurality of notification pulses can be updated automatically.

[0044] In some examples, the progression of a disease state, the effects of a therapeutic substance, damage and / or migration of lead 108, the onset of acute pain, changes in chronic pain, injury or degeneration of one or more nerves, and / or changes in discomfort perceived by patient 102 can result in changes to the sensed ECAP signal over time when patient 102 is in the same postural state. In such examples, based on differences in signal characteristic(s) between a currently sensed evoked signal and a previous evoked signal, system 100 (e.g., IMD 106, external programmer 120) can adjust parameters of the electrical stimulation therapy, for example, until IMD 106 determines that the signal characteristic(s) of the currently sensed evoked signal are within target range(s) based on target characteristics of the previous evoked signal. Signal characteristics of the ECAP signal can include, but are not limited to, a nerve conduction velocity of the signal, an amplitude of a portion of the signal (e.g., an amplitude between two peaks), an area under one or more peaks, a frequency content, and / or a maximum peak timing and / or a minimum peak timing.

[0045] In some examples, the patient 102 can switch from a first posture state to a second posture state, e.g., from sitting to standing. In such examples, the electrical stimulation therapy configured for the first posture state can elicit ECAP signals having signal characteristics outside of the target range(s) of target characteristics in the second posture state. In such examples, the system 100 can adjust parameters of the electrical stimulation therapy until the IMD 106 detects that the currently sensed ECAP signals have signal characteristics within the target range(s) of target characteristics in the second posture state. The target range of signal characteristics or target characteristic values can be derived from previous ECAP signals received during a posture state in which patient input indicating a level of comfort or a level of discomfort in that posture state was provided.

[0046] In Figure 1 In examples, the IMD 106 is described as performing a number of processing and computational functions. For example, the IMD 106 can determine a current posture state of the patient 102, receive sensed ECAP signals corresponding to the electrical stimulation therapy, determine whether the sensed ECAP signal(s) are within the target range(s) of target characteristic(s) for that posture state, and adjust parameters of the electrical stimulation therapy to elicit ECAP signals having signal characteristic(s) within the target range(s). The IMD 106 can perform the number of processing and computational functions in a closed loop process, i.e., without additional input from an external programmer 120, clinician, or patient 102. In some examples, the IMD 106 can receive the posture state of the patient 102 and the target range(s) of target characteristic(s) for that posture state from an external computing device and / or system, e.g., from the external programmer 120.

[0047] In some examples, the ECAP signal characteristic(s) for each posture state can change accordingly as the disease state of the patient 102 progresses over time. The IMD 106 can be configured to adjust the target range(s) of target characteristic(s) based on changes in the disease state. Similarly, in some examples, use of a particular therapeutic substance can affect physiological parameters of the patient 102, e.g., nerve conduction velocity, and in turn affect the ECAP signal characteristics. The IMD 106 can be configured to detect the presence of an effect of any therapeutic substance based on changes in the ECAP signal characteristics. Based on such a determination, the IMD 106 can adjust parameters of the electrical stimulation therapy to account for the effect of the therapeutic substance, and / or adjust the target range(s) of target characteristic(s) to account for the effect of the therapeutic substance. Additionally or alternatively, the IMD 106 can detect changes in the patient disease state by receiving additional patient input that changes a level of comfort or a level of discomfort of the therapy even if the signal characteristics remain within the target range.

[0048] In some examples, patient 102 can experience an acute onset of pain or discomfort. In other medical devices, patient input indicating perception of an acute onset can cause the medical device to unnecessarily adjust parameters of electrical stimulation therapy. Once the acute onset subsides, the medical device must revert the adjustment to the therapy parameters. Such changes can not resolve the acute onset of pain and can, for example, increase the discomfort of patient 102 contrary due to changes in electrical stimulation therapy.

[0049] In response to patient input indicating perception of an acute onset of pain or discomfort, IMD 106 can determine whether the sensed ECAP signal corresponds to the patient input. If the sensed ECAP signal does not correspond to pain or discomfort, IMD 106 can maintain the current parameters of electrical stimulation therapy. Maintaining the current parameters can reduce unnecessary power consumption and / or reduce discomfort perceived by patient 102 after the acute onset subsides. In some examples, IMD 106 can temporarily deliver a single dose of electrical stimulation to alleviate any acute pain or discomfort perceived by patient 102. If the characteristics of the ECAP signal do correspond to a change in patient comfort or discomfort, IMD 106 can determine an ECAP change corresponding to the patient input identifying the change in comfort and adjust the target ECAP value or range used, adjust stimulation.

[0050] In some examples, lead 108 can become dislodged, damaged, or caused to shift within the tissue of patient 102, for example, in response to a fall, car accident, or the like. In response to sensor data and / or patient input indicating an event in which acceleration changes drastically, IMD 106 can determine whether the signal characteristic(s) of the sensed ECAP signal after the event occurred are within the target range(s) of the target characteristic(s) for the current patient posture state. Based on determining that the signal characteristic(s) are outside the target range(s), IMD 106 can determine a likelihood that lead 108 is damaged or shifted and notify patient 102, for example, via external programmer 120 and / or an external computing device (e.g., a smartwatch, a smartphone, a tablet computer, a laptop computer, or the like).

[0051] In example techniques described in this disclosure, the target stimulation signal values (e.g., target ranges of characteristic value(s)) of the control stimulation parameters and stimulation signal can be initially set at a clinic, but can also be set and / or adjusted by the patient 102 at home. Once the target stimulation signal values (e.g., target ranges of characteristic value(s)) are set, the example techniques allow for automatic adjustment of the parameters of the stimulation pulses in order to maintain a consistent amount of neural activation and a consistent perception of therapy for the patient 102 as the distance of the electrodes to the neurons changes. The ability to change the stimulation parameter value(s) can also allow for therapy to have long-term efficacy, enabling the intensity of the stimulation (e.g., as indicated by the detected stimulation signal) to be maintained consistently by comparing the measured characteristic value(s) of the stimulation signal to the target ranges of characteristic values. The IMD 106 can perform these changes without intervention by a physician or the patient 102.

[0052] Figure 2 is a block diagram illustrating an example configuration of components of the IMD 106 in accordance with one or more techniques of this disclosure. In Figure 2 In the example shown, the IMD 106 includes a stimulation generation circuit 202, a switch circuit 204, a sensing circuit 206, a communication circuit 208, a processing circuit 210, a storage device 212, sensor(s) 221, and a power source 218. The components of the IMD 106 can be fixed within a housing 220.

[0053] In Figure 2 In the example shown, the storage device 212 stores the therapy stimulation programs 214 and the patient scenarios 216 in separate memories within the storage device 212 or separate areas within the storage device 212. Each of the stored therapy stimulation programs in the therapy stimulation programs 214 defines values for a set of electrical stimulation parameters (e.g., a set of stimulation parameters) such as a stimulation electrode combination, electrode polarity, current or voltage amplitude, pulse width, pulse rate, and pulse shape. In examples in which control pulses are provided to the patient without informing the pulses, a separate test stimulation program can not be needed. Instead, a test stimulation program for therapy that includes only control pulses can define the same control pulses as the corresponding therapy stimulation program for those control pulses.

[0054] Accordingly, in some examples, the stimulation generation circuit 202 generates electrical stimulation signals in accordance with the above-described electrical stimulation parameters. Other ranges of stimulation parameter value(s) can also be used, which can depend on the target stimulation site within the patient 102. While stimulation pulses are described, the stimulation signals can have any form, such as continuous-time signals (e.g., sinusoids), etc. The switching circuit 204 can include one or more switch arrays, one or more multiplexers, one or more switches (e.g., a switch matrix or other collection of switches), or other circuitry configured to direct stimulation signals from the stimulation generation circuit 202 to one or more of the electrodes 224A-D (collectively referred to herein as "electrodes 224"), or to direct sensing signals from one or more of the electrodes 222, 224 to the sensing circuit 206. In other examples, the stimulation generation circuit 202 and / or the sensing circuit 206 can include sensing circuitry that directs signals to and / or from one or more of the electrodes 222 and 224, which can or can not include the switching circuit 204.

[0055] The sensing circuit 206 monitors signals from any combination of the electrodes 222, 224. In some examples, the sensing circuit 206 includes one or more amplifiers, filters, and analog-to-digital converters. The sensing circuit 206 can be used to sense physiological signals, such as ECAP signals or other evoked signals. In some examples, the sensing circuit 206 detects electrical signals, such as ECAPs from a particular combination of the electrodes 222, 224. In some examples, the particular combination of electrodes used to sense ECAPs includes different electrodes than a set of electrodes 222, 224 used to deliver stimulation pulses. Alternatively, in other cases, the particular combination of electrodes used to sense ECAPs includes at least one of the same electrodes as a set of electrodes used to deliver stimulation pulses to the patient 102. The sensing circuit 206 can provide signals to an analog-to-digital converter for conversion to digital signals for processing, analysis, storage, or output by the processing circuit 210.

[0056] Under the control of the processing circuit 210, the communication circuit 208 supports communication by the IMD 106 with external programmers (e.g., an external programmer 104) and other devices. The communication circuit 208 can include one or more transmitters, receivers, and / or transceivers, and associated circuitry, such as one or more processors, microprocessors, digital signal processors, software, firmware, memory, and / or other circuitry. The communication circuit 208 can support wired and / or wireless communication, such as communication via Bluetooth®, Bluetooth Low Energy, ZigBee®, Wi-Fi, WiMAX, cellular, or other communication protocol. Figure 2Wireless communication between the IMD 106 (not shown) and another computing device. The processing circuitry 210 of the IMD 106 can receive multiple values ​​of various stimulation parameters (e.g., amplitude and electrode combinations) from an external programmer via the communication circuitry 208 as updates to the program. Updates to the therapeutic stimulation program 214 can be stored in the storage device 212. The communication circuitry 208 in the IMD 106, as well as communication circuitry in other devices and systems described herein (e.g., external programmers), can communicate via radio frequency (RF) communication technology. Additionally, the communication circuitry 208 can interact with an external medical device programmer (IMD 106) via proximity sensing interaction with the external programmer. Figure 2 (Not shown in the image) Communication. An external programmer can be... Figure 1 An example of an external programmer 120. Therefore, the communication circuit 208 can continuously, at periodic intervals, or upon request from the IMD 106 or the external programmer.

[0057] Processing circuitry 210 may include any 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), discrete logic circuitry, or any other processing circuitry configured to provide functionality attributable to processing circuitry 210, which may be embodied herein as firmware, hardware, software, or any combination thereof. Processing circuitry 210 controls stimulation generation circuitry 202 to generate stimulation signals according to therapeutic stimulation program 214 stored in storage device 212, applying stimulation parameter values(s) specified by one or more programs, such as the amplitude, pulse width, pulse rate, and pulse shape of each stimulation signal.

[0058] exist Figure 2 In the example shown, a set of electrodes 222 includes electrodes 222A, 222B, 222C, and 222D, and a set of electrodes 224 includes electrodes 224A, 224B, 224C, and 224D. In other examples, a single lead may include all eight electrodes 222 and 224 along a single axial length of the lead. Processing circuitry 210 also controls stimulation generation circuitry 202 to generate stimulation signals and apply them to selected combinations of electrodes 222, 224. In some examples, stimulation generation circuitry 202 includes switching circuitry (as an alternative to or complement to switching circuitry 204) that can couple stimulation signals to selected conductors within leadry 108, which in turn deliver stimulation signals across selected electrodes 222, 224. Such switching circuitry may be a switch array, switch matrix, multiplexer, or configured to selectively couple stimulation energy to selected electrodes 222, 224 and selectively utilize selected electrodes 222, 224 to sense bioelectric nerve signals in the patient's spinal cord. Figure 2any other type of switching circuitry (not shown).

[0059] In other examples, however, the stimulation generation circuitry 202 does not include switching circuitry, and the switching circuitry 204 does not interface between the stimulation generation circuitry 202 and the electrodes 222, 224. In these examples, the stimulation generation circuitry 202 includes pairs of voltage sources, current sources, voltage sinks, or current sinks connected to each electrode 222, 224, such that each pair of electrodes has a unique signal circuit. In other words, in these examples, each of the electrodes 222, 224 is independently controlled via its own signal circuit (e.g., via a combination of regulated voltage sources and sinks or regulated current sources and sinks), as opposed to switching signals between the electrodes 222, 224.

[0060] The electrodes 222, 224 on the respective lead 108 can be configured in a variety of different designs. For example, one or both of the leads 108 can include one or more electrodes at each longitudinal position along the length of the lead, such as one electrode at each of the different perimeter positions A, B, C, D on the perimeter of the lead. In one example, the electrodes can be electrically coupled to the stimulation generation circuitry 202 via respective conductive wires that are straight or coiled within the housing of the lead and extend to a connector at the proximal end of the lead. In another example, each electrode of the lead can be an electrode disposed on a thin film. The thin film can include a conductive trace for each electrode that extends the length of the thin film to the proximal connector. The thin film can then be wrapped (e.g., in a spiral) around an inner member to form the lead 108. These and other configurations can be used to construct leads with complex electrode geometries.

[0061] Although the sensing circuitry 206 is embedded in the common housing 220 with the stimulation generation circuitry 202 and the processing circuitry 210 in Figure 2 In other examples, the sensing circuitry 206 can be in a different housing from the IMD 200 and can communicate with the processing circuitry 210 via wired or wireless communication techniques. In some examples, the sensing circuitry 206 can be disposed in a separate IMD and can communicate with the IMD 200 via wired communication techniques or wireless communication techniques.

[0062] In some examples, one or more of the electrodes 222 and 224 are adapted to sense one or more ECAPs. For example, the electrodes 222 and 224 can sense a voltage amplitude of a portion of the ECAP signal, where the sensed voltage amplitude is a characteristic of the ECAP signal.

[0063] The storage device 212 can be configured to store information within the IMD 106 during operation. The storage device 212 can include a computer- readable storage medium or computer-readable storage device. In some examples, the storage device 212 includes one or more of a short-term memory or a long-term memory. The storage device 212 can include, for example, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), magnetic discs, optical discs, flash memory, or forms of electrical programmable memory (EPROM) or electrically erasable programmable memory (EEPROM). In some examples, the storage device 212 is used to store data indicative of instructions executed by the processing circuit 210. As discussed above, the storage device 212 is configured to store the therapy stimulation programs 214 and the patient scenarios 216.

[0064] The patient scenarios 216 can include a plurality of patient scenarios. Each patient scenario can be based on a different combination of a comfort level (e.g., a pain level value perceived by the patient 102), a corresponding posture state of the patient 102, and a signal property value(s) of a corresponding sensed ECAP signal for the respective posture state. At least some of the patient scenarios can include a corresponding ECAP signal that achieves a desired comfort level for a given posture. Such patient scenarios can be referred to herein as “baseline patient scenarios,” and the corresponding ECAP signals can be referred to herein as “baseline ECAP signals.” Each baseline patient scenario can include a corresponding posture state and a target property(s) of the baseline ECAP signal for that posture state. The target property(s) can be based at least in part on a previously sensed ECAP signal. The target property(s) can include, but are not limited to, an amplitude of a portion of the signal, a neural conduction velocity of the signal, an area under one or more peaks, a frequency content, and / or a maximum peak timing and / or a minimum peak timing. For each target property, the patient scenarios 216 can store one or more target values. In some examples, the patient scenarios 216 can store a target range(s) of values and / or a target value(s) for each target property. The target range(s) of a target property can be a range of values for each posture state within which the patient (e.g., via patient input) indicates that the patient does not perceive pain or discomfort. In some examples, the target range(s) of a target property can be an amount of deviation from a single value for each posture state at which the patient indicates that no pain or discomfort is perceived for that particular posture state of the plurality of posture states. In some examples, each patient state within the patient scenarios 216 and / or each target property can correspond to one or more of the therapy stimulation programs 214.

[0065] In some examples, the stimulation generation circuit 202 can be configured to deliver electrical stimulation therapy to the patient 102. In some examples, the electrical stimulation therapy can include a plurality of notification pulses. Additionally, the stimulation generation circuit 202 can be configured to deliver a plurality of control pulses, where the plurality of control pulses are interleaved with at least some of the plurality of notification pulses. The stimulation generation circuit 202 can deliver the plurality of notification pulses and the plurality of control pulses to a target tissue (e.g., the spinal cord 104) of the patient 102 via the electrodes 222, 224 of the lead 108. By delivering such notification pulses and control pulses, the stimulation generation circuit 202 can cause the IMD 106 to sense a stimulation signal indicative of the delivered pulses. Additionally or alternatively, the stimulation generation circuit 202 can deliver control pulses that evoke detectable responsive ECAPs in the target tissue, which propagate through the target tissue and then return to the electrodes 222, 224. The IMD 106 can not be able to detect the stimulation signal or ECAPs caused or elicited by the notification pulses, or the IMD 106 can not be configured to sense the ECAPs elicited by the notification pulses. In some examples, a different combination of electrodes 222, 224 can sense the responsive ECAPs and / or responsive stimulation signals than the combination of electrodes 222, 224 that deliver the notification pulses and the combination of electrodes 222, 224 that deliver the control pulses. The sensing circuit 206 can be configured to detect the responsive ECAPs and / or responsive stimulation signals via the electrodes 222, 224 and the lead 108. In other examples, the stimulation generation circuit 202 can be configured to deliver the plurality of control pulses without delivering any notification pulses when the control pulses also provide a therapeutic effect to the patient or contribute to a therapeutic effect on the patient.

[0066] In some examples, the stimulation generation circuit 202 can deliver multi-modal stimulation (e.g., differential targeting multiplexed stimulation). Multi-modal stimulation includes different stimulation pulses (e.g., pre-excitation stimulation pulses and base stimulation pulses) defined by different stimulation parameters, such as different frequencies and different electrode combinations. Because different types of cells, such as glial cells and neurons, react differently to electric fields, the reactions of these cell populations can be differentially modulated with significantly different electrical parameters. For example, pre-excitation stimulation pulses can be delivered to affect glial cells (e.g., in the spinal cord 104), and base stimulation pulses can be delivered to affect neurons. Typically, the pre-excitation stimulation pulses are delivered at a higher pulse frequency than the base stimulation pulses, as described in more detail herein.

[0067] In some cases, processing circuitry 210 can instruct sensing circuitry 206 to continuously monitor the ECAP signal. In other cases, processing circuitry 210 can instruct sensing circuitry 206 to monitor the ECAP signal periodically and / or based on a signal from sensor(s) 221. In some examples, activating and deactivating sensing circuitry 206 to monitor the ECAP signal periodically rather than continuously can prolong the battery life of power source 218.

[0068] Processing circuitry 210 can determine a posture state of patient 102, for example, based on data from sensor(s) 221. For example, processing circuitry 210 can determine a posture state of patient 102 based on accelerometer data from an accelerometer disposed within housing 220. In some examples, processing circuitry 210 can receive patient input indicative of a posture state of patient 102 via communication circuitry 208. IMD 106 can sense an ECAP signal from tissue of patient 102, for example, via sensing circuitry 206, and determine signal characteristic(s) of the ECAP signal. In some examples, IMD 106 can receive a signal corresponding to or representative of the ECAP signal and determine signal characteristic(s) of the ECAP signal based on the received signal. Processing circuitry 210 can receive patient input indicative of a level of comfort perceived by patient 102 at a first time via communication circuitry 208. The level of comfort perceived by patient 102 can include the presence and / or level of pain experienced by patient 102 at the first time.

[0069] Processing circuitry 210 can generate patient scenario 216 based at least in part on the posture state of patient 102, the sensed ECAP signal and / or determined signal characteristic(s) of the sensed ECAP signal, and the patient input indicative of the level of comfort perceived by patient 102. For example, for each time period (e.g., a first time), processing circuitry 210 can determine a posture state of patient 102, a corresponding patient input indicative of a level of comfort perceived by patient 102, and a corresponding sensed ECAP signal and / or determined signal characteristic(s). For each posture state, processing circuitry 210 can aggregate the corresponding levels of comfort, sensed ECAP signals, and / or determined signal characteristic(s) over a plurality of time periods.

[0070] For each posture state, processing circuitry 210 can determine target values of the determined signal property(s) of the ECAP signal, e.g., to achieve a desired level of comfort perceived by patient 102. The desired level of comfort perceived by patient 102 can be programmed and / or adjusted by a clinician, external programmer 120, and / or patient 102, and can include a threshold level of pain, no pain, no discomfort, etc. For example, for a given posture state, processing circuitry 210 can determine a time period in which patient 102 experiences no discomfort. Processing circuitry 210 can then determine the signal property(s) of the ECAP signal during that time period. Processing circuitry 210 can then select the determined signal property(s) during that time period as the target property(s), and select the values of the determined signal property(s) as the target values of the target property(s). The target values of the target property(s) can be target values of the target property(s) of a baseline ECAP signal of patient 102 in the given posture state. The baseline for each posture state can include the ECAP signal property value(s) corresponding to the desired level of comfort perceived by patient 102 in the posture state.

[0071] Patient 102 can experience an increased level of pain or discomfort over time (e.g., due to changes in the disease state of patient 102, due to the effects of a therapeutic substance administered to patient 102). In such examples, processing circuitry 210 determines the posture state of patient 102 and compares the currently sensed signal property(s) of the ECAP signal to the target signal property(s) for that posture state (e.g., stored in patient context 216). Processing circuitry 210 can determine whether patient 102 is perceiving an increased level of discomfort based on the comparison (e.g., as compared to the desired level of comfort). For example, based on a determination that the determined signal property(s) of the currently sensed ECAP signal deviate outside of the target range(s) of the corresponding target property(s), processing circuitry 210 can determine that patient 102 is perceiving an increased level of discomfort. Processing circuitry 210 can then adjust parameters of the electrical stimulation therapy to account for the increased level of discomfort and cause stimulation generation circuitry 202 to deliver the adjusted therapy to patient 102. Processing circuitry 210 can repeat this process until processing circuitry 210 determines that the determined signal property(s) of the currently sensed ECAP signal are within the target range(s) of the corresponding target property(s) (e.g., patient 102 is perceiving the desired level of comfort).

[0072] In some examples, the patient 102 can change posture from a first posture state to a second posture state. In such examples, the processing circuitry 210 can compare the determined signal characteristic(s) of the currently sensed ECAP signal to the target value(s) of the corresponding target characteristic(s) for the second posture state (e.g., as stored in the patient context 216). The processing circuitry 210 can then adjust the parameters of the electrical stimulation therapy and cause the stimulation generation circuitry 202 to deliver the adjusted therapy to the patient 102. The processing circuitry 210 can iteratively adjust the parameters of the electrical stimulation therapy until the processing circuitry 210 determines that the determined signal characteristic(s) of the currently sensed ECAP signal are within the target range of the corresponding target characteristic(s) for the second posture state.

[0073] In some examples, the patient 102 can experience an acute onset of pain or discomfort. The processing circuitry 210 can receive a patient input via the communication circuitry 208 indicating that the patient 102 experiences an acute onset of pain or discomfort. The processing circuitry 210 can determine whether any changes in the ECAP signal correspond to the patient input. Based on identifying a change in the ECAP signal that corresponds to the patient input, the processing circuitry 210 can adjust the parameters of the electrical stimulation therapy. In some examples, if the processing circuitry 210 fails to identify any corresponding changes in the ECAP signal, the processing circuitry 210 can adjust (e.g., temporarily adjust) or maintain the parameters of the electrical stimulation therapy. The temporary adjustment or maintenance of the parameters can reduce the power consumption of the components of the IMD 106 and / or reduce patient discomfort while the acute onset subsides. In some examples, one or more therapy stimulation programs 214 can be pre-selected (e.g., by a clinician) to address acute onsets of pain or discomfort. In such examples, the processing circuitry 210 can select the pre-selected therapy stimulation program 214 (e.g., based on the posture state of the patient 102, based on the signal characteristic(s) of the ECAP signal, based on the level of discomfort perceived by the patient 102) and cause the stimulation generation circuitry 202 to deliver a single dose of electrical stimulation therapy according to the selected therapy stimulation program 214, e.g., until the patient 102 no longer perceives the pain or discomfort.

[0074] In some examples, a high energy impact (e.g., a fall, a car accident, etc.) experienced by the patient 102 can damage the lead 108 and / or cause the lead 108 to shift, e.g., away from tissue proximate to the spinal cord 104. In such examples, the change in the position and / or integrity of the lead 108 can alter the electrical signals delivered by the lead 108 to the nerve, which in turn alters the ECAP signal sensed along the nerve.

[0075] The processing circuit 210 can determine the occurrence of a shock event, for example, based on a rapid change in acceleration detected by the sensor(s) 221. Based on the determination, the processing circuit 210 can compare the determined signal characteristic(s) of the currently sensed ECAP signal to the target value(s) of the corresponding target characteristic(s) for the current posture state of the patient 102. Based on a determination that the determined signal characteristic(s) exceed the target range(s), the processing circuit 210 can determine that the lead 108 can be damaged, displaced, and / or otherwise changed due to the shock event. The processing circuit 210 can then cause the communication circuit 208 to notify the clinician, an external programmer (e.g., the external programmer 120), and / or the patient 102 of the potential damage and / or displacement due to the shock event. In some examples, based on the determination that the lead 108 can be damaged and / or displaced, the processing circuit 210 can then initiate a comprehensive diagnostic procedure to assess the integrity of the lead 108.

[0076] The power source 218 is configured to deliver operating power to the components of the IMD 106. The power source 218 can include a battery and power generation circuitry to produce the operating power. In some examples, the battery is rechargeable to allow extended operation. In some examples, recharging is accomplished through inductive interactions between an external charger and an inductive charging coil within the IMD 106. The power source 218 can include any one or more of a variety of different battery types, such as nickel cadmium, and lithium ion.

[0077] Figure 3 is a block diagram illustrating an example configuration of components of the external programmer 120 in accordance with one or more techniques of this disclosure. Although the external programmer 120 can generally be described as a handheld device, the external programmer 120 can be a larger portable device or a more fixed device. Additionally, in other examples, the external programmer 120 can be included as part of, or include the functionality of, an external charging device. As Figure 3 As illustrated in FIG. 3, the external programmer 120 can include a processing circuit 302, a storage device 304, a user interface (UI) 306, a communication circuit 358, and a power source 310. The storage device 304 can store instructions that, when executed by the processing circuit 302, cause the processing circuit 302 and the external programmer 120 to provide the functionality attributed to the external programmer 120 in this disclosure. Each of these components, circuits, or modules can include circuitry configured to perform some or all of the functions described herein. For example, the processing circuit 302 can include processing circuitry configured to perform the processes discussed with respect to the processing circuit 302.

[0078] Generally, external programmer 120 includes any suitable hardware arrangement, alone or in combination with software and / or firmware, to perform the techniques attributed to external programmer 120, as well as processing circuitry 302, user interface 306, and communication circuitry 308 of external programmer 120. In various examples, external programmer 120 can include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. In various examples, external programmer 120 can also include a storage device 304, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, hard disks, CD-ROMs, the storage device including executable instructions to cause the one or more processors to perform the actions attributed to the processors. Additionally, while processing circuitry 302 and communication circuitry 308 are described as separate modules, in some examples, processing circuitry 302 and communication circuitry 308 are functionally integrated. In some examples, processing circuitry 302 and communication circuitry 308 correspond to separate hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0079] Storage device 304 (e.g., a memory device) can store instructions that, when executed by processing circuitry 302, cause processing circuitry 302 and external programmer 120 to provide the functionality attributed to external programmer 120 in this disclosure. For example, storage device 304 can include instructions that cause processing circuitry 302 to instruct IMD 106 to deliver stimulation pulses to patient 102 in accordance with one or more therapy stimulation programs 214 (not shown) stored in one or more of IMD 106 or external programmer 120. In some examples, storage device 304 can store information corresponding to previously sensed ECAP signals and / or patient scenarios 216 (not shown). For example, storage device 305 can store characteristic values of one or more ECAP signals sensed by IMD 106 and corresponding posture states (e.g., corresponding sensor data from sensor(s) 221 of IMD 106, corresponding patient input). Some of patient scenarios 216 can include different posture states of patient 102 and corresponding target values of target characteristic(s) of baseline ECAP signals of patient 102 for the particular posture state.

[0080] The storage device 304 can include a plurality of therapy stimulation programs, where each program includes a set of parameters defining stimulation pulses, such as pre- excitatory stimulation pulses and / or basal stimulation pulses. The storage device 304 can also store data received from a medical device, e.g., the IMD 106. The data can include, but is not limited to, sensed stimulation signals, sensed ECAP signals, and stimulation parameters (e.g., timing parameters) configured to be delivered by the medical device. For example, the storage device 304 can store stimulation signals and / or ECAP related data recorded at a sensing module of the medical device, and the storage device 304 can also store data from one or more sensors of the medical device.

[0081] The user interface 306 can include buttons or a keypad, lights, voice command speakers, displays such as liquid crystal (LCD), light emitting diodes (LED), or organic light emitting diodes (OLED). In some examples, the display includes a touch screen. The user interface 306 can be configured to display any information related to the delivery of electrical stimulation, identified patient behaviors, sensed patient parameter values, patient behavior criteria, or any other such information. The user interface 306 can also receive patient input via the user interface 306. The patient input can be in the form of, for example, pressing a button on a keypad or selecting an icon from a touch screen. The patient input can indicate a level of comfort perceived by the patient 102 at a particular point in time (e.g., a current perceived level of comfort by the patient 102). The patient input can also include an indication of a current posture state of the patient 102 (e.g., standing, sitting, squatting, lying down, etc.). In some examples, the patient 102 can input patient input to the user interface 306 indicating a sudden onset of pain or discomfort (i.e., acute pain) is perceived.

[0082] The communication circuitry 308 can support wireless communication between the IMD 106 and the external programmer 120 under the control of the processing circuitry 302. The communication circuitry 308 can also be configured to communicate with another computing device via a wireless communication technology or directly through a wired connection. In some examples, the communication circuitry 308 provides wireless communication via an RF or proximity inductive medium. The other computing device can include a medical device (e.g., a wearable medical device, an IMD) configured to communicate with the IMD 106 and the external programmer 120. In such examples, the IMD 106 can communicate with the external programmer 120 via the medical device and can not communicate directly with the external programmer 120. In some examples, the communication circuitry 308 includes an antenna, which can take a variety of forms, such as an internal or external antenna.

[0083] Examples of local wireless communication techniques that can be used to facilitate communication between external programmer 120 and IMD 106 include RF communication according to the 802.11 standard, or the Bluetooth® specification set, or other standard or proprietary telemetry protocols. In this manner, other external devices can be able to communicate with external programmer 120 without the need to establish a secure wireless connection. As described herein, communication circuitry 308 can be configured to transmit spatial electrode movement patterns or other stimulation parameter value(s) to IMD 106 for use in delivering electrical stimulation therapy.

[0084] In some examples, the stimulation parameters of the therapy stimulation program 214 are transmitted to IMD 106 for delivery to the patient (e.g., patient 102). In other examples, the therapy can include medication, activities, or other instructions that patient 102 can perform themselves or that a caregiver can perform for patient 102. In some examples, external programmer 120 provides a visual, audible, and / or tactile notification indicating that there is a new instruction. In some examples, external programmer 120 requires receiving patient input confirming that the instruction has been completed. Figure 1

[0085] According to the techniques of this disclosure, user interface 306 of external programmer 120 receives an indication from a clinician instructing a processor of a medical device (e.g., processing circuitry 210 of IMD 106) to update one or more of therapy stimulation programs or to generate and / or update a patient scenario 216 stored in the medical device. Updating a therapy stimulation program can include changing one or more parameters (e.g., timing parameters) of stimulation pulses delivered by IMD 106 according to the program, such as amplitude, pulse width, frequency, timing, pulse shape, and / or pulse type (e.g., informed pulses, control pulses, pre-excitation pulses, foundation pulses). Updating a patient scenario can include updating target value(s) and / or target range(s) of target characteristic(s) of ECAP signals of one or more posture states stored in patient scenario 216. User interface 306 can also receive instructions from the clinician commanding the start or stop of any electrical stimulation, including control pulses and / or informed pulses.

[0086] ​In some examples, based on instructions received via user interface 306, processing circuitry 302 can transmit patient input information to a medical device (e.g., to IMD 106) via communication circuitry 308. IMD 106 can then perform the functions previously described herein based at least in part on the patient input received from communication circuitry 308. For example, IMD 106 can generate and / or update a patient scenario (e.g., in patient scenario 216) that defines various target values and / or ranges for target characteristics of baseline ECAP signals for various posture states. In some examples, IMD 106 can determine whether to adjust parameters of electrical stimulation therapy based on receiving patient input indicating an acute episode of pain or discomfort perceived by patient 102. In some examples, IMD 106 can adjust target values for baseline ECAP signals and / or one or more therapy stimulation programs based on the received patient input. In some examples, processing circuitry 302 can cause communication circuitry 308 to transmit instructions on how to adjust the target values and / or the one or more therapy stimulation programs. In some examples, processing circuitry 210 of IMD 106 can automatically perform the adjustments in a closed loop process (e.g., based on sensed ECAP signals and / or received patient input). In some examples, in the event that patient 102 reports an acute episode of pain or discomfort that IMD 106 is unable to correspond to a change in sensed ECAP signals, processing circuitry 302 can cause communication circuitry 308 to transmit instructions on a predetermined electrical stimulation therapy (e.g., stimulation parameters of a predetermined electrical stimulation therapy) and cause IMD 106 to deliver a single dose of stimulation based on the predetermined electrical stimulation therapy, e.g., to alleviate the acute pain or discomfort experienced by patient 102.

[0087] Power source 310 is configured to deliver operating power to the components of external programmer 120. Power source 310 can include a battery and power generation circuitry to produce the operating power. In some examples, the battery is rechargeable to allow prolonged operation. Recharging can be accomplished through electrical coupling to a cradle or plug that is connected to an alternating current (AC) outlet. Additionally, recharging can be accomplished through inductive interaction between an external charger and an inductive charging coil within external programmer 120. In other examples, traditional batteries (e.g., cadmium nickel or lithium ion) can be used. Additionally, external programmer 120 can be directly coupled to an AC outlet to operate.

[0088] Figure 4 is a plot 400 of example evoked compound action potentials (ECAPs) sensed for respective stimulation pulses in accordance with the techniques of this disclosure. As Figure 4As shown, plot 400 illustrates an example ECAP signal 402 (dashed line) and ECAP signal 404 (solid line). In some examples, each of ECAP signals 402 and 404 are sensed from a stimulation pulse (e.g., control pulse, foundation pulse) delivered from a guard cathode, where the stimulation pulse is a biphasic pulse including an interphase interval between each positive phase and negative phase of the pulse. In some such examples, the guard cathode includes a stimulation electrode at the end of an 8-electrode lead (e.g., lead 108), while two sensing electrodes are provided at the other end of the 8-electrode lead. ECAP signal 402 demonstrates a voltage amplitude that is sensed as a result of a sub-detection threshold stimulation pulse or a stimulation pulse that results in an undetectable ECAP. It should be noted that there can be single phase, triphasic, or pulses with another number of phases in other examples. Figure 1

[0089] A peak 406 of ECAP signal 402 is detected, and this peak represents the stimulation signal of the delivered stimulation pulse. However, no propagating signal is detected following the stimulation signal in ECAP signal 402 because the strength (e.g., amplitude and / or pulse width) of the stimulation pulse is "sub-threshold" or below a detection threshold (e.g., sub-detection threshold) and / or below a propagation threshold (e.g., sub-propagation threshold).

[0090] In contrast to ECAP signal 402, ECAP signal 404 represents a voltage amplitude that is detected from a stimulation pulse that is above a detection stimulation threshold. A peak 406 of ECAP signal 404 is detected, and this peak represents the stimulation signal of the delivered stimulation pulse. Following peak 406, ECAP signal 404 also includes peaks PI, Nl, and P2, which are three representative peaks representing propagating action potentials from the ECAP. An example duration of the stimulation signal and peaks PI, Nl, and P2 is approximately 1 millisecond (ms).

[0091] ​When an ECAP of the ECAP signal 404 is detected, different characteristic(s) can be identified. For example, a characteristic of the ECAP can be the amplitude between N1 and P2. The N1-P2 amplitude can be easily detected even though the stimulation signal affects the relatively larger signal of P1, and the N1-P2 amplitude can be least affected by electronic drift in the signal. In other examples, a characteristic of the ECAP used to control a subsequent stimulation pulse (e.g., a control pulse and / or an informed pulse) can be the amplitude of P1, N1, or P2 relative to a neutral voltage or zero voltage. In some examples, a characteristic of the ECAP used to control a subsequent stimulation pulse is the sum of two or more of the peak P1, N1, or P2. In other examples, a characteristic of the ECAP signal 404 can be the area under one or more of the peak P1, N1, and / or P2. In other examples, a characteristic of the ECAP can be a ratio of one of the peak P1, N1, or P2 to another of these peaks. In some examples, a characteristic of the ECAP is the slope between two points in the ECAP signal, such as the slope between N1 and P2. In other examples, a characteristic of the ECAP can be the time between two points of the ECAP, such as the time between N1 and P2.

[0092] The time between the time when a stimulation pulse is delivered and a point in the ECAP signal can be referred to as the latency of the ECAP and can be indicative of the type of fiber captured by the stimulation pulse (e.g., control pulse). In this way, a latency can be determined from a number of points on the sensed ECAP signal. An ECAP signal with a lower latency (i.e., a smaller latency value) indicates a higher percentage of neural fibers with a higher signal propagation speed, while an ECAP signal with a higher latency (i.e., a larger latency value) indicates a higher percentage of neural fibers with a slower signal propagation speed. Latency can also refer to the time between detecting an electrical feature at one electrode and then detecting the electrical feature again at a different electrode. This time or latency is inversely proportional to the conduction velocity of the neural fiber. Other characteristic(s) of the ECAP signal can be used in other examples. In some examples, changes in pain can be reflected by different fiber activations, which can manifest as changes in latency.

[0093] The amplitude of the ECAP signal can increase with increasing stimulation pulse amplitude, as long as the pulse amplitude is greater than a threshold value, thereby depolarizing the nerve and propagating the signal, and there are additional fibers to be activated with increasing stimulation pulse amplitude. When an informed pulse is determined to be delivered to the patient 102 as an effective therapy, a target ECAP characteristic (e.g., a target ECAP amplitude) can be determined from the ECAP signal detected from the stimulation pulse (or control pulse). Thus, the ECAP signal is representative of the distance between the stimulation electrode and the nerve, which is appropriate for the stimulation parameter value(s) of the informed pulse delivered at the time. Additionally, the ECAP signal can be related to the patient posture state and the perception of the level of comfort by the patient 102. In such examples, the ECAP signal can be used to represent the level of comfort perceived by the patient 102 in a given posture state (e.g., when the patient 102 is standing, when the patient 102 is sitting).

[0094] When the patient 102 remains in a certain posture state, the position of the electrodes of the IMD 106 can remain constant relative to the target tissue of the patient 102. Nonetheless, the ECAP signal detected by the IMD 106 can change over time, e.g., due to progression of the disease state of the patient 102, effects of therapeutic substances. Additionally, the ECAP signal detected by the IMD 106 can change when the patient 102 changes posture states. The IMD 106 can use changes in the detected measured ECAP characteristic values to change the stimulation parameter value(s), e.g., to cause the patient 102 to perceive a target level of comfort. In some examples, the IMD 106 can update the target value(s) and / or target range(s) of the target ECAP characteristic of the baseline ECAP signal based on the detected changes in the measured ECAP characteristic.

[0095] Figure 5 A timing diagram 500 illustrating examples of electrical stimulation pulses, corresponding stimulation signals, and corresponding sensed ECAPs in accordance with one or more techniques of the present disclosure. For convenience, the IMD 106 of Figure 2 is described with reference to Figure 5 . As illustrated, the timing Figure 5 includes a first channel 502, a plurality of stimulation pulses 504A-504N (collectively, “stimulation pulses 504”), a second channel 506, and a plurality of corresponding ECAPs 508A-508N (collectively, “ECAPs 508”). In some examples, the stimulation pulses 504 can represent control pulses configured to elicit ECAPs 508 that can be detected by the IMD 200, but this is not required. In some examples, the stimulation pulses 504 can represent foundation pulses. The stimulation pulses 504 can represent any type of pulse deliverable by the IMD 200. In Figure 5In the example of FIG. 6, IMD 200 can deliver therapy with control pulses instead of notification pulses or without using notification pulses.

[0096] First channel 502 is a time / voltage (and / or current) graph indicating the voltage (or current) of at least one of electrodes 222, 224. In one example, the stimulation electrodes of first channel 502 can be located on an opposite side of the lead from the sensing electrodes of second channel 506. Stimulation pulses 504 can be electrical pulses delivered to the patient’s spinal cord by at least one of electrodes 222, 224 and can be shown as having a negative phase and a positive phase separated by an interphase interval. For example, the amount of time and the magnitude of the negative voltage of stimulation pulses 504 can be the same as its positive voltage. Note that the negative voltage phase can precede or follow the positive voltage phase. Stimulation pulses 504 can be delivered according to a therapy stimulation program 214 stored in storage device 212 of IMD 106. Therapy stimulation program 214 can be updated according to patient input via an external programmer (e.g., external programmer 120). Each of stimulation pulses 504 can have a pulse width of less than about 300 microseconds (e.g., the total time of the positive phase, the negative phase, and the interphase interval is less than 300 microseconds). In some examples, each of stimulation pulses 504 can have a pulse width of about 100 μβ for each phase of the biphasic pulse. As Figure 5 shown, stimulation pulses 504 can be delivered via channel 502. The delivery of stimulation pulses 504 can be delivered by lead 108 in a protected cathode electrode combination. For example, if lead 108 is a linear 8 electrode lead, the protected cathode combination is the central cathode electrode and the anode electrode immediately adjacent to the cathode electrode.

[0097] Second channel 506 is a time / voltage (and / or current) graph indicating the voltage (or current) of at least one of electrodes 222, 224. In one example, the electrodes of second channel 506 can be located on an opposite side of the lead from the electrodes of first channel 502. In response to stimulation pulses 504, ECAPs 508 can be sensed from the patient’s spinal cord at electrodes 222, 224. ECAPs 508 are electrical signals that can propagate along the nerve away from the origin of stimulation pulses 504. In one example, ECAPs 508 are sensed by a different electrode than the electrode used to deliver stimulation pulses 504. As Figure 5 shown, ECAPs 508 can be recorded on second channel 506.

[0098] Figure 6A is a conceptual diagram illustrating a spine 602 of patient 102 in a first posture 600A in accordance with one or more techniques of this disclosure. Figure 6B is a conceptual diagram illustrating a spine 602 of patient 102 in a second posture 600B in accordance with one or more techniques of this disclosure. Figure 6AA conceptual diagram of a spine 602. The spine 602 includes a plurality of vertebrae 604 extending downward along the back of the patient 102. Adjacent vertebrae 604 are separated by intervertebral discs 606. The vertebrae 604 define a passage extending along the spine 602. Each of the vertebrae 604 defines a spinous process 608 on the dorsal side of the spine 602, which at least partially defines the passage. The spinal cord 104 is situated within the passage of the vertebrae 604 extending through the spine 602. The vertebrae 604 may include spinous processes 608 extending away from the spinal cord 104.

[0099] One or more leads 108 can be implanted in the epidural space adjacent to the spinal cord 104 or spine 602. In some examples, such as Figure 6A and Figure 6B As shown, one or more leads 108 (e.g., lead 108A) may be positioned within a channel defined by vertebra 604 and adjacent to spinal cord 104. As shown, lead 108A includes electrodes 222 disposed at different longitudinal positions along at least a distal portion of its length. Each of the electrodes 222 may be configured to deliver an electrical stimulation signal to nerves and / or fiber bundles that are part of and / or extend from spinal cord 104, and / or sense electrical signals from these nerves and / or fiber bundles (e.g., ECAP). Each of the electrodes 222 may deliver an electrical stimulation signal and / or sense electrical signals from different regions along the length of spinal cord 104. In some examples, lead 108 may be positioned laterally or anterolaterally relative to spinal cord 104 to sense pain signals that may travel through lateral portions of the spinal cord and / or dorsal roots. In some examples, a sensing lead can be placed at this lateral location, and the stimulation lead can be positioned more medially relative to the spinal cord 104. This sensing lead, placed closer to the potential source of the pain signal, can use ECAP or other signals as described herein to improve pain sensing.

[0100] like Figure 6A and Figure 6BAs demonstrated, as the patient 102 transitions between posture states (e.g., transitions from the first posture 600A to the second posture 600B), the spinal column 602 and the spinal cord 104 can transition accordingly. Movement of the spinal column 602 and the spinal cord 104 can cause the lead 108 to move within the epidural space in the spinal column 602 and position the electrodes 222 proximate to different nerves and / or fiber tracts connected to the spinal cord 104. In some examples, as the spinal column 602 and the spinal cord 104 move, the lead 108 can remain relatively static, thereby positioning the electrodes 222 proximate to different nerves and / or fiber tracts. For example, due to physiological differences of the nerves, proximity of the electrodes 222 to the nerves and / or to the spinal cord 104, etc., the change in connection between the electrodes 222 and the nerves of the patient 102 can cause the IMD 106 to detect ECAP signals having different signal characteristic values. In some examples, one or more of the electrodes 222 can also remain proximate to the same nerves and / or fiber tracts despite changes in the posture state of the patient 102. In such examples, the IMD 106 can detect ECAP signals having the same signal characteristic values for different posture states.

[0101] Within each posture state, the position of the electrodes 222 can remain substantially constant with respect to the sensed ECAP signal characteristics. Thus, for each posture state, the system 100 can associate a particular signal characteristic value with a different level of comfort perceived by the patient 102. Based on the association of the signal characteristic values with the different levels of comfort, the system 100 can determine a baseline ECAP signal for each posture state and a best target value and / or a target range for each target characteristic of each baseline ECAP signal. The system 100 can then generate a patient scenario (e.g., the patient scenario 216) in which, for each posture state (e.g., for the first posture 600A, for the second posture 600B), the system 100 stores the target value and / or the target range for the target characteristic(s) of the sensed ECAP signal.

[0102] Figure 7 is a flowchart illustrating an example process for delivering stimulation therapy to a patient based on sensed evoked signals and patient posture states in accordance with one or more techniques of this disclosure. While Figure 7 The system 100 is described with reference to one IMD (e.g., the IMD 106), but the system 100 can include two or more IMDs. Additionally, while Figure 7 The example processes of are primarily described as being performed by the IMD 106 of the system 100, but the example processes described below can be performed by another medical device (e.g., a wearable medical device, another IMD), an external programmer of the system 100 (e.g., the external programmer 120), and / or other computing devices, systems, and / or cloud computing environments in communication with any component of the system 100.

[0103] IMD 106 can receive a first signal representative of a first evoked electrical signal elicited by delivery of electrical stimulation during a posture state (702). IMD 106 can receive the first signal from one or more sensors within IMD 106, such as from sensor(s) 221. In some examples, system 100 can receive the first signal from electrodes disposed on an implantable lead (e.g., lead 108) connected to IMD 106 (e.g., electrodes 222, 224). IMD 106 can process the received first signal to identify the first evoked electrical signal. The first evoked electrical signal can include a first ECAP signal, but in some examples, the first evoked electrical signal can include other action potential signals.

[0104] IMD 106 can determine a posture state of patient 102 based on sensor data from sensor(s) 221 of IMD 106. For example, IMD 106 can determine an orientation of IMD 106 based on sensor data from sensor(s) 221 and determine a posture state (e.g., standing, squatting, hunched, sitting, lying down) of patient 102 based on the determined orientation of IMD 106. Sensor(s) 221 can include, but are not limited to, an accelerometer, a gyroscope, and / or an inertial measurement unit (IMU). In some examples, system 100 can determine or confirm a posture state based on patient input received by external programmer 120 and / or based on external sensor data (e.g., from a camera connected to system 100). IMD 106 can receive the determined posture state via external programmer 120. In some examples, the sensor(s) can be disposed external to IMD 106 and within, on, or otherwise associated with patient 102. For example, the sensor(s) can be disposed on a computer device (e.g., smartwatch, smartphone) worn or used by patient 102. The sensor(s) can be in communication with IMD 106 and / or external programmer 120 and can transmit sensor data to IMD 106.

[0105] IMD 106 can determine a first signal characteristic of the first evoked electrical signal (704). The signal characteristic can include, but is not limited to, an amplitude of a portion of the first evoked electrical signal, a neural conduction velocity of the signal, an area under one or more peaks of the first evoked electrical signal, a frequency content, and / or a maximum peak timing and / or a minimum peak timing of the first evoked electrical signal. IMD 106 can determine a value of the one or more first signal characteristics based on the first evoked electrical signal.

[0106] IMD 106 can receive patient input indicating a level of comfort associated with the first evoked electrical signal during the posture state (706). IMD 106 can receive patient input indicating a level of comfort perceived by patient 102 at different times, for example, via user interface 306 of external programmer 120. IMD 106 can then correlate the level of comfort with the first evoked electrical signal in time to determine a level of comfort associated with the first evoked electrical signal. The level of comfort perceived by patient 102 can include a presence or absence of pain or discomfort perceived by patient 102, a type of pain or discomfort perceived by patient 102, a location of pain or discomfort perceived by patient 102, and / or a level of pain or discomfort perceived by patient 102. For example, patient input can indicate that patient 102 is perceiving pain, that patient 102 is perceiving sharp pain (e.g., as opposed to dull pain, throbbing pain, etc.), that patient 102 is perceiving sharp pain in the lower back, and / or that patient 102 is perceiving the sharp pain as moderate (e.g., according to a pain scale).

[0107] In some examples, IMD 106 can detect a plurality of evoked electrical signals during the posture in addition to the first evoked electrical signal and associate a level of comfort with each evoked electrical signal. The plurality of evoked electrical signals can be associated with varying levels of comfort. IMD 106 can determine a relationship between one or more signal characteristics of the evoked electrical signals and the level of comfort perceived by patient 102 based on the plurality of evoked electrical signals and the associated levels of comfort.

[0108] IMD 106 can determine a target characteristic for the posture state based on the first signal characteristic and the patient input (708). IMD 106 can determine a desired level of comfort for patient 102 in the posture state based on the first signal characteristic and the patient input. The desired level of comfort can include an absence of pain and / or discomfort, or can include a presence of pain and / or discomfort below a threshold level of severity. The desired level of comfort can be predetermined by a clinician or patient 102 and transmitted to IMD 106 via external programmer 120. For each posture state, IMD 106 can identify a desired level of comfort and determine a target value(s) and target range(s) of one or more signal characteristics of the evoked electrical signals that can be related to the desired level of comfort. The one or more signal characteristics can also be referred to as target characteristic(s) for the posture state.

[0109] In some examples, IMD 106 can determine that the first evoked electrical signal corresponds to a desired level of comfort and store the target characteristic value of the first evoked electrical signal as a target value and / or a target range. In some examples, IMD 106 can determine a deviation between the level of comfort corresponding to the first evoked electrical signal and the desired level of comfort and calculate a target value and / or a target range for the target characteristic based on the level of deviation from the desired level of comfort and the target characteristic value of the first evoked electrical signal. In some examples, IMD 106 can determine a target value and / or a target range for the target characteristic based on a plurality of evoked electrical signals and corresponding levels of comfort.

[0110] IMD 106 can determine a target value and / or a target range for each of the one or more target characteristics and for the target characteristic for each of the one or more posture states. In some examples, different posture states can use different target characteristics. In some examples, the target value for a same target characteristic for different posture states can be the same, for example, because the electrodes of lead 108 of IMD 106 sense evoked electrical signals from the same nerve and / or the same nerve fiber bundle. The target value and / or the target range for the target characteristic(s) can be stored in IMD 106 (e.g., in patient context 216 of storage device 212) and / or transmitted to external programmer 120. In some examples, the target value and / or the target range for the target characteristic(s) can define a baseline evoked electrical signal for a posture state.

[0111] In some examples, IMD 106 can adjust the electrical stimulation therapy based at least in part on the target value and / or the target range for the target characteristic(s) of the baseline evoked electrical signal. For example, IMD 106 can determine a minimum stimulation amplitude that is capable of generating the baseline evoked electrical signal (e.g., a minimum amplitude configured to cause patient 102 to perceive a desired level of comfort, a minimum amplitude configured to reduce or eliminate pain or discomfort perceived by patient 102). IMD 106 can then determine a parameter value(s) for the electrical stimulation therapy based on the determined minimum stimulation amplitude and deliver electrical stimulation to patient 102 based on the determined parameter value(s). Delivering electrical stimulation with a minimum stimulation amplitude can reduce excess power consumption and increase the operational life of IMD 106, thereby requiring fewer medical procedures to replace IMD 106 and / or replace a power source of IMD 106. An increased operational life of IMD 106 can also increase the amount of time between charging sessions for IMD 106.

[0112] IMD 106 can receive a second signal representative of a second evoked electrical signal elicited by the electrical stimulation during the posture state (710). The second signal can be later in time than the first signal, and can be in response to a different electrical stimulation pulse. IMD 106 can determine the second evoked electrical signal based on the second signal. IMD 106 can determine values of one or more signal characteristics for the second evoked electrical signal. The one or more signal characteristics of the second evoked electrical signal can be the same as the target characteristic type(s) for the posture state.

[0113] IMD 106 can control one or more parameters of subsequent electrical stimulation based on the second signal characteristic of the second evoked electrical signal and the target characteristic (712). IMD 106 can compare the second signal characteristic of the one or more signal characteristics of the second evoked electrical signal to the target characteristic, for example, to determine a deviation between the first evoked electrical signal and the second evoked electrical signal. The deviation can be caused by movement and / or damage of lead 108, progression of the disease state, effects of a therapeutic substance, changes in physiology of patient 102, etc. Based on the deviation, the electrical stimulation can no longer cause patient 102 to perceive the desired level of comfort. If IMD 106 determines that the deviation is outside of the target range, IMD 106 can control one or more parameters of the electrical stimulation therapy (e.g., electrode combination, voltage or current amplitude, pulse width, pulse frequency) to cause patient 102 to perceive the desired level of comfort.

[0114] Changing the one or more parameters can also change one or more aspects of the evoked electrical signal. IMD 106 can iteratively adjust the one or more parameters until IMD 106 determines that the deviation of the value of the second signal characteristic of the evoked electrical signal is within the target range of the target value of the target characteristic. IMD 106 can determine that the deviation between the second signal characteristic and the target characteristic exceeds a threshold amount, and adjust the one or more parameters based on the determination. In some examples, IMD 106 can determine the deviation between the first evoked electrical signal or the baseline electrical signal and the second evoked electrical signal based on a comparison of two or more signal characteristics to corresponding target characteristics.

[0115] In some examples, changes in patient physiology and / or progression of a patient disease state can affect the ability of the neural to propagate and / or affect characteristics of the evoked electrical signal generated by the neural in response to the electrical stimulation signal. These changes can be reflected in a difference between the second signal characteristic and the target characteristic. In some examples, IMD 106 can adjust the target characteristic to account for such changes. IMD 106 can adjust the target value and / or the target range of the target characteristic, for example, to match a value of the second signal characteristic, to match a median or average of a plurality of signal characteristics including the second signal characteristic, or otherwise adjust the target value and / or the target range based at least in part on the second signal characteristic.

[0116] Figure 8 An example process is shown for controlling one or more parameters of a subsequent electrical stimulation based on a second signal characteristic of a second evoked electrical signal and a target characteristic(s) (i.e., Figure 7 The steps of the example process of 712) are described above with reference to the example system of Figure 1 and the example process of Figure 7 Although the example processes described herein can be performed by any of the example devices, systems, or methods described in the present disclosure.

[0117] The IMD 106 can receive a second signal representing a second evoked electrical signal evoked by the electrical stimulation during the posture state (710). The IMD 106 can then determine a second signal characteristic of the second evoked electrical signal (802). For example, the IMD 106 can determine one or more of the following for the second evoked electrical signal: an amplitude of a portion of the second evoked electrical signal, a neural conduction velocity of the second evoked electrical signal, an area under one or more peaks of the second evoked electrical signal, a frequency of the second evoked electrical signal, and / or a maximum peak timing and / or a minimum peak timing of the second evoked electrical signal. The second signal characteristic can be the same type as one of the target characteristics of the posture state. For example, both the second signal characteristic and the target characteristic can be a frequency of a respective evoked electrical signal (e.g., the second evoked electrical signal, the baseline evoked electrical signal).

[0118] The IMD 106 can determine whether a deviation of the second signal characteristic from the target characteristic reaches a threshold amount (804). The IMD 106 can determine whether a deviation between a value of the second signal characteristic and a value within the target value(s) and / or target range of the target characteristic reaches a threshold amount. The threshold amount can be pre-determined by a clinician and transmitted to the IMD 106 by the external programmer 120. In some examples, the IMD 106 can adjust the threshold amount based on changes in the signal characteristic of the sensed evoked electrical signal over time, for example to account for changes in patient physiology, changes in patient disease state, etc.

[0119] Based on determining that the deviation of the second signal characteristic from the target characteristic does not reach the threshold amount (“NO” branch of 804), IMD 106 can deliver subsequent electrical stimulation based on one or more parameters (808). The value of the one or more parameters of the subsequent electrical stimulation can be similar or identical to the value of the one or more parameters of the previously delivered electrical stimulation (e.g., the electrical stimulation that evoked the second evoked electrical signal). IMD 106 can notify patient 102 that the electrical stimulation is within the target range (810). IMD 106 can continue to deliver electrical stimulation to patient 102 at the same parameter values and / or according to the same predetermined therapy stimulation program. While delivering the subsequent electrical stimulation based on the one or more parameters, IMD 106 can continue to receive signals representative of evoked electrical signals evoked by the subsequent electrical stimulation during the posture state of patient 102 (710).

[0120] Based on determining that the deviation of the second signal characteristic from the target characteristic reaches the threshold amount (“YES” branch of 804), IMD 106 can adjust one or more parameters of the subsequent electrical stimulation (806). IMD 106 can select the one or more parameters from a plurality of parameters based on predetermined instructions stored in storage device 212 of IMD 106. In some examples, IMD 106 can select the one or more parameters based on the type of the second signal characteristic. In some examples, IMD 106 can select the one or more parameters based on the magnitude of the deviation between the second signal characteristic and the target characteristic.

[0121] IMD 106 can deliver subsequent electrical stimulation to tissue of patient 102 based on the one or more parameters (808). The subsequent electrical stimulation can be defined by the adjusted values of the one or more parameters and can be delivered to the same tissue or different tissue of patient 102 depending on the adjusted values. The subsequent electrical stimulation is configured to cause patient 102 to perceive a desired level of comfort in the current posture state. IMD 106 can notify patient 102 that the electrical stimulation is within the target range (810).

[0122] IMD 106 can iteratively perform steps 710-808 of the example process of Figure 8 until IMD 106 receives an indication from patient 102 to terminate delivery of electrical stimulation, to temporarily stop delivery of electrical stimulation, or to switch to another therapy stimulation program.

[0123] Figure 9 is a flowchart of an example process for determining damage and / or displacement of an electrical lead (e.g., lead 108) within patient 102’s body based on sensed evoked signals and posture states of patient 102 in accordance with one or more techniques of the present disclosure. While Figure 9The primary description is to determine the occurrence of an impact event (e.g., a fall, a car crash, etc.) using accelerations experienced by the patient 102, but other sensor data can be used. Other sensor data can include, but is not limited to, changes in sensor orientation and / or changes in forces, pressures, and / or velocities detected by the sensors.

[0124] The IMD 106 can determine the occurrence of an impact event (902). The IMD 106 can detect a change in acceleration experienced by the patient 102. The IMD 106 can include sensor(s) 221 (e.g., accelerometer, IMU) configured to detect changes in acceleration experienced by the IMD 106. In some examples, the sensor(s) can be coupled to the patient 102 and can be in communication with the IMD 106 and / or the external programmer 120. The IMD 106 can determine whether a magnitude of the detected acceleration satisfies a threshold condition. The threshold condition can be based on a minimum acceleration magnitude experienced by the IMD 106 in an impact event that can damage or move the lead 108 within the patient 102. Based on determining that the magnitude of the change in acceleration satisfies the threshold condition, the IMD 106 can determine the occurrence of an “impact event.” The IMD 106 can transmit the detected acceleration magnitude and accompanying contextual information (e.g., a timestamp of the change in acceleration) to the external programmer 120.

[0125] The IMD 106 can receive a signal representative of an evoked electrical signal elicited by the electrical stimulation following the impact event (904). For example, in accordance with the example processes previously described in Figure 7 and Figure 8 The IMD 106 can further determine a value of a signal characteristic of the evoked electrical signal, in accordance with the example processes previously described in

[0126] The IMD 106 can receive patient input indicative of a level of comfort perceived by the patient 102 (906). The IMD 106 can cause the external programmer 120 (e.g., via the user interface 306) to request patient input indicative of a level of comfort perceived by the patient 102. The level of comfort can be a current level of comfort perceived by the patient 102 if the request for patient input is relatively close in time to the impact event (e.g., within seconds, less than an hour, following the impact event). In some examples, the request for patient input occurs after a period of time (e.g., hours, days) has elapsed since the impact event. The IMD 106 can request patient input indicative of a level of comfort perceived by the patient 102 at a time immediately following the occurrence of the impact event. The IMD 106 can cause the external programmer 120 to provide a relevant time to help the patient recall.

[0127] IMD 106 can determine a threshold condition for a signal characteristic corresponding to a level of comfort (908). IMD 106 can determine a threshold for a signal characteristic at a given posture state and a level of comfort perceived by patient 102 based on one or more of patient scenarios 216. For example, if patient 102 indicates that a desired level of comfort is perceived, the threshold can be a target value for a target characteristic of a baseline evoked electrical signal. As another example, if patient 102 indicates that a perceived level of comfort deviates from a desired level of comfort by a first amount, IMD 106 can determine a value for the target characteristic based on a first amount of deviation from a target value for a target characteristic of a baseline evoked electrical signal. In some examples, IMD 106 can determine a target range of possible values for the target characteristic for a given level of comfort.

[0128] IMD 106 can determine whether the signal characteristic of the evoked electrical signal satisfies the threshold (910). Based on a determination that the threshold is satisfied (YES branch of 910), IMD 106 can determine that the electrode of IMD 106 is sensing an expected ECAP signal at a given level of comfort perceived by patient 102 and take no further action. In such examples, IMD 106 can still repeat the example process illustrated in FIG. 6 or another lead integrity verification process at a later time, e.g., to verify the determination. Figure 9

[0129] Based on a determination that the signal characteristic of the evoked electrical signal does not satisfy the threshold (NO branch of 910), IMD 106 can notify patient 102 that the electrical lead can be damaged and / or displaced (912), e.g., via external programmer 120. IMD 106 can further notify a clinician that lead damage and / or displacement can have occurred. In some examples, IMD 106 can perform an additional lead integrity verification process, e.g., to verify the determination.

[0130] The following examples are example systems, devices, and methods described herein.

[0131] ​Example 1: A system comprising: processing circuitry configured to: receive, via sensing circuitry of the system, a first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determine a first signal characteristic of the one or more first evoked electrical signals for the posture state; receive, via one or more user devices of the system, patient input indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determine a target characteristic for the posture state based on the first signal characteristic and the patient input; receive, via the sensing circuitry, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and control one or more parameters based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation to the patient during the posture state.

[0132] Example 2: The system of Example 1, wherein at least one of the one or more first evoked electrical signals and the one or more second evoked electrical signals comprises an evoked compound action potential (ECAP) signal.

[0133] Example 3: The system of any one of Examples 1 and 2, wherein the processing circuitry is further configured to determine the posture state of the patient based at least in part on signals received from an accelerometer associated with the patient.

[0134] Example 4: The system of any one of Examples 1-3, wherein to control the one or more parameters, the processing circuitry is further configured to: determine whether a deviation of the second signal characteristic from the target characteristic reaches a threshold amount; and based on determining that the deviation of the second signal characteristic from the target characteristic reaches the threshold amount, adjust the one or more parameters.

[0135] Example 5: The system of Example 4, wherein the processing circuitry is further configured to: sense, via the sensing circuitry, a third signal representing one or more third evoked electrical signals sensed in the tissue and elicited by the subsequent delivery of the electrical stimulation; determine a third signal characteristic of the third evoked electrical signals; determine whether a deviation of the third signal characteristic from the target characteristic reaches the threshold amount; and based on determining that the deviation of the third signal characteristic from the target characteristic is less than the threshold amount, notify the one or more user devices that the electrical stimulation is within a target range.

[0136] Example 6: The system of any of examples 4 and 5, wherein the processing circuit is further configured to adjust the target characteristic of the posture state based at least in part on the second signal characteristic.

[0137] Example 7: The system of any of examples 1-6, wherein the patient input comprises a level of pain experienced by the patient for the electrical stimulation, and wherein the processing circuit is further configured to: determine a correlation between the second signal characteristic and the patient input; and adjust the one or more parameters based at least in part on the correlation.

[0138] Example 8: The system of any of examples 1-7, wherein to control the one or more parameters, the processing circuit is configured to: determine a minimum stimulation amplitude for reducing pain experienced by the patient based on the first signal characteristic and the patient input; determine one or more parameter values for the electrical stimulation based at least in part on the determined minimum amplitude; and adjust the one or more parameters of the electrical stimulation to the one or more parameter values.

[0139] Example 9: The system of any of examples 7 and 8, wherein the processing circuit is configured to: determine a plurality of patient scenarios based on a plurality of combinations of one or more of pain level values, signal characteristic values, or patient posture states from a range of possible pain level values, possible signal characteristic values, and possible patient posture states, respectively, wherein each patient scenario comprises one or more predetermined parameter values that at least partially define the electrical stimulation; select a patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input, wherein each patient scenario of the plurality of patient scenarios comprises one or more predetermined parameters that at least partially define the electrical stimulation delivered to the patient; and adjust the one or more parameters to the one or more predetermined parameter values.

[0140] Example 10: The system of example 9, wherein the processing circuit is further configured to adjust the one or more predetermined parameter values of one or more patient scenarios of the plurality of patient scenarios or the minimum stimulation amplitude based at least in part on the one or more second evoked electrical signals.

[0141] Example 11: The system of any of examples 9 and 10, wherein the processing circuit is configured to: determine a minimum stimulation amplitude for each of the plurality of patient scenarios; select the patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and based on the selected patient scenario, adjust the one or more parameters based on the minimum stimulation amplitude of the selected patient scenario.

[0142] Example 12: The system of any of examples 1-11, wherein the patient input comprises first patient input, and wherein the processing circuit is further configured to: receive, via the one or more user devices, second patient input indicating that the patient is being affected by a medication; determine, based on the one or more second evoked electrical signals, an effect of the medication on the second signal characteristic; and adjust the one or more parameters based at least in part on the effect of the medication on the second signal characteristic.

[0143] Example 13: The system of example 12, wherein the second signal characteristic comprises a nerve conduction velocity of the patient, and wherein the processing circuit is configured to determine an effect of the medication on the nerve conduction velocity of the patient.

[0144] Example 14: The system of any of examples 1-13, wherein the processing circuit is further configured to: determine, based on the patient input, a level of comfort perceived by the patient; determine whether at least one of the one or more second evoked electrical signals satisfies a threshold condition corresponding to the level of comfort; and based on a determination that the at least one second evoked electrical signal satisfies the threshold condition, transmit, to the one or more user devices, a notification indicating that an electrical lead coupled with a medical device is displaced or damaged, wherein the medical device is configured to deliver the electrical stimulation to the patient during the posture state.

[0145] Example 15: The system of example 14, wherein the threshold condition comprises a threshold evoked electrical signal amplitude for the determined level of comfort and the posture state.

[0146] Example 16: The system of any of examples 1-15, wherein the processing circuit is further configured to: determine, based on the patient input, that the patient is experiencing pain; and determine, based on the second signal characteristic, whether a change in the one or more second evoked electrical signals relative to the one or more first evoked electrical signals corresponds to the pain experienced by the patient.

[0147] Example 17: The system of example 16, wherein the processing circuit is further configured to: based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain, maintain the one or more parameters that at least partially define the electrical stimulation.

[0148] Example 18: The system of example 16, wherein the processing circuit is further configured to: based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain, adjust the one or more parameters that at least partially define the electrical stimulation.

[0149] Example 19: The system of Example 18, wherein the processing circuit is configured to adjust the one or more parameters to a predetermined level based on determining that the change in the one or more second evoked electrical signals does not correspond to the pain, wherein the predetermined level is configured to reduce acute pain experienced by the patient.

[0150] Example 20: The system of any of Examples 1-19, wherein the first signal characteristic and the second signal characteristic each include a maximum amplitude of the one or more first evoked electrical signals and the one or more second evoked electrical signals, respectively.

[0151] Example 21 : The system of any of Examples 1-20, further comprising a stimulation generator configured to deliver electrical stimulation to the patient via one or more electrodes electrically connected with the stimulation generator, and wherein the processing circuit is configured to control delivery of the electrical stimulation by controlling the one or more parameters that at least partially define the delivery of the electrical stimulation.

[0152] Example 22: A method comprising: receiving, by processing circuit of a medical device system, a first signal via sensing circuit of the medical device system, the first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determining, by the processing circuit, a first signal characteristic of the one or more first evoked electrical signals for the posture state; receiving, by the processing circuit, patient input from one or more user devices, the patient input indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determining, by the processing circuit, a target characteristic for the posture based on the first signal characteristic and the patient input; receiving, by the processing circuit via the sensing circuit, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and controlling, by the processing circuit, one or more parameters based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation to the patient during the posture state.

[0153] Example 23: The method of Example 22, wherein at least one of the one or more first evoked electrical signals and the one or more second evoked electrical signals includes an evoked compound action potential (ECAP) signal.

[0154] Example 24: The method of any of examples 22 and 23, further comprising determining, by the processing circuit, a posture state of the patient based at least in part on a signal received from an accelerometer associated with the patient.

[0155] Example 25: The method of any of examples 22 to 24, wherein controlling the one or more parameters comprises: determining, by the processing circuit, whether a deviation of the second signal characteristic from the target characteristic reaches a threshold amount; and adjusting, by the processing circuit, the one or more parameters based on a determination that the deviation of the second signal characteristic from the target characteristic reaches the threshold amount.

[0156] Example 26: The method of example 25, further comprising: sensing, by the processing circuit via the sensing circuit, a third signal representing one or more third evoked electrical signals sensed in the tissue and elicited by the subsequent delivery of the electrical stimulation; determining, by the processing circuit, a third signal characteristic of the third evoked electrical signals; determining, by the processing circuit, whether a deviation of the third signal characteristic from the target characteristic reaches the threshold amount; and based on a determination that the one or more third signal characteristics deviate from the target characteristic by less than the threshold amount, notifying, by the processing circuit via the one or more user devices, the patient that the electrical stimulation is within a target range.

[0157] Example 27: The method of any of examples 25 and 26, further comprising adjusting, by the processing circuit, the target characteristic of the posture state based at least in part on a second signal characteristic.

[0158] Example 28: The method of any of examples 22 to 27, wherein the patient input comprises a level of pain experienced by the patient with respect to the electrical stimulation, and wherein the method further comprises: determining, by the processing circuit, a correlation between the second signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters based at least in part on the correlation.

[0159] Example 29: The method of any of examples 22 to 28, wherein controlling the one or more parameters comprises: determining, by the processing circuit, a minimum stimulation amplitude for reducing pain experienced by the patient based on the first signal characteristic and the patient input; determining, by the processing circuit, one or more parameter values for the electrical stimulation based at least in part on the determined minimum amplitude; and adjusting, by the processing circuit, the one or more parameters of the electrical stimulation to the one or more parameter values.

[0160] Example 30: The method of any of examples 28 and 29, further comprising: determining, by the processing circuit, a plurality of patient scenarios based on a plurality of combinations of one or more of pain level values, signal characteristic values, or patient posture states from a range of possible pain level values, possible signal characteristic values, and possible patient posture states, respectively, wherein each patient scenario includes one or more predetermined parameter values that at least partially define the electrical stimulation; determining, by the processing circuit, a minimum stimulation amplitude for each of the plurality of patient scenarios; selecting, by the processing circuit, a patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters to the one or more predetermined parameter values.

[0161] Example 31 : The method of example 30, further comprising adjusting, by the processing circuit, the one or more predetermined parameter values of one or more patient scenarios of the plurality of patient scenarios based at least in part on the second signal characteristic.

[0162] Example 32: The method of any of examples 30 and 31, further comprising: determining, by the processing circuit, a minimum stimulation amplitude for each of the plurality of patient scenarios; selecting, by the processing circuit, the patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters based on the minimum stimulation amplitude of the corresponding patient scenario.

[0163] Example 33: The method of any of examples 22 to 32, wherein the patient input includes a first patient input, and wherein the method further comprises: receiving, by the processing circuit via the one or more user devices, a second patient input indicating that the patient is being affected by a medication; determining, by the processing circuit, an effect of the medication on the second signal characteristic based on the one or more second evoked electrical signals; and adjusting, by the processing circuit, the one or more based at least in part on the effect of the medication on the second signal characteristic.

[0164] Example 34: The method of example 33, wherein the second signal characteristic includes a nerve conduction velocity of the patient, and wherein the method further comprises: determining, by the processing circuit, an effect of the medication on the nerve conduction velocity of the patient.

[0165] Example 35: The method of any one of examples 22 to 34, further comprising: determining, by the processing circuit, a level of comfort perceived by the patient based on the patient input; determining, by the processing circuit, whether at least one of the one or more second evoked electrical signals satisfies a threshold condition corresponding to the level of comfort; and based on determining that the at least one second evoked electrical signal satisfies the threshold condition, transmitting, by the processing circuit, a notification to the patient via the one or more user devices indicating one or more of: a possible dislodgement of an electrical lead, or a possible damage to at least one electrode of one or more electrodes disposed on the electrical lead.

[0166] Example 36: The method of example 35, wherein the threshold condition comprises a threshold sensed evoked electrical signal amplitude for the determined level of comfort and the posture state by the patient.

[0167] Example 37: The method of any one of examples 22 to 36, further comprising: determining, by the processing circuit, that the patient is experiencing pain based on the patient input; and determining, by the processing circuit, whether a change in the one or more second evoked electrical signals relative to the one or more first evoked electrical signals corresponds to the pain experienced by the patient based on the second signal characteristic.

[0168] Example 38: The method of example 37, further comprising maintaining, by the processing circuit, the one or more parameters based on determining that the change in the one or more second evoked electrical signals does not correspond to the pain.

[0169] Example 39: The method of example 37, further comprising adjusting, by the processing circuit, the one or more parameters based on determining that the change in the one or more second evoked electrical signals does not correspond to the pain.

[0170] Example 40: The method of example 39, further comprising adjusting, by the processing circuit, the one or more parameters of the electrical stimulation to one or more predetermined values based on determining that the change in the one or more second evoked electrical signals does not correspond to the pain, wherein the one or more predetermined values are configured to mitigate acute pain experienced by the patient.

[0171] Example 41: The method of any one of examples 22 to 40, wherein the first signal characteristic and the second signal characteristic each comprise a maximum amplitude of the one or more first evoked electrical signals and the one or more second evoked electrical signals, respectively.

[0172] Example 42: A computer-readable medium comprising instructions that, when executed, cause a processing circuit of an implantable medical device system to perform the method of any of examples 22-41.

[0173] The techniques described in this disclosure can be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the techniques can be implemented within one or more microprocessors, DSPs, ASICs, FPGAs or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in external devices, such as physician or patient programmers, stimulators, or other devices. The term "processor" and "processing circuitry" should be interpreted in broad terms to encompass any of the foregoing circuitry, as well as any other integrated or discrete logic circuits. ASICs are typically programmed by techniques of logic programming, such as Hardy logic programming.

[0174] For aspects implemented in software, at least some of the functionality attributed to the systems and devices described in this disclosure can be embodied as instructions on a computer-readable storage medium such as RAM, DRAM, SRAM, magnetic disks, optical disks, flash memory, or EPROM or EEPROM form. Such instructions can be executed to support one or more aspects of the functionality described in this disclosure.

[0175] Moreover, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules. Different embodiments are depicted with discrete features to emphasize different aspects of the functionality, but it is understood that these features can be combined in a single hardware or software module, or multiple hardware or software modules. Further, the functionality described herein can be implemented in one or more circuits or logic elements. The techniques of this disclosure can be implemented in a wide variety of devices or apparatuses, including an IMD, an external programmer, a combination of an IMD and external programmer, an integrated circuit (IC) or ICs, and / or discrete electrical circuitry, such as resides in an IMD and / or external programmer.

[0176] Further disclosed herein are the subject matter of the following examples:

[0177] Example 1 : A system comprising: processing circuitry configured to: receive, via sensing circuitry of the system, a first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determine a first signal characteristic of the one or more first evoked electrical signals for the posture state; receive, via one or more user devices of the system, patient input indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determine a target characteristic for the posture state based on the first signal characteristic and the patient input; receive, via the sensing circuitry, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and control one or more parameters based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation to the patient during the posture state.

[0178] Example 2: The system of claim 1, wherein at least one of the one or more first evoked electrical signals and the one or more second evoked electrical signals comprises an evoked compound action potential (ECAP) signal.

[0179] Example 3: The system of any one of claims 1 and 2, wherein the processing circuitry is further configured to determine the posture state of the patient based at least in part on signals received from an accelerometer associated with the patient.

[0180] Example 4: The system of any one of claims 1 to 3, wherein to control the one or more parameters, the processing circuitry is further configured to: determine whether a deviation of the second signal characteristic from the target characteristic reaches a threshold amount; and based on determining that the deviation of the second signal characteristic from the target characteristic reaches the threshold amount, adjust the one or more parameters.

[0181] Example 5: The system of claim 4, wherein the processing circuitry is further configured to: sense, via the sensing circuitry, a third signal representing one or more third evoked electrical signals sensed in the tissue and elicited by the subsequent delivery of the electrical stimulation; determine a third signal characteristic of the third evoked electrical signals; determine whether a deviation of the third signal characteristic from the target characteristic reaches the threshold amount; and based on determining that the deviation of the third signal characteristic from the target characteristic is less than the threshold amount, notify the one or more user devices that the electrical stimulation is within a target range.

[0182] Example 6: The system of any of claims 4 and 5, wherein the processing circuit is further configured to adjust the target characteristic of the posture state based at least in part on the second signal characteristic.

[0183] Example 7: The system of any of claims 1 to 6, wherein the patient input comprises a level of pain experienced by the patient for the electrical stimulation, and wherein the processing circuit is further configured to: determine a correlation between the second signal characteristic and the patient input; and adjust the one or more parameters based at least in part on the correlation.

[0184] Example 8: The system of any of claims 1 to 7, wherein to control the one or more parameters, the processing circuit is configured to: determine a minimum stimulation amplitude for reducing pain experienced by the patient based on the first signal characteristic and the patient input; determine one or more parameter values for the electrical stimulation based at least in part on the determined minimum amplitude; and adjust the one or more parameters of the electrical stimulation to the one or more parameter values.

[0185] Example 9: The system of any of claims 7 and 8, wherein the processing circuit is configured to: determine a plurality of patient scenarios based on a plurality of combinations of one or more of pain level values, signal characteristic values, or patient posture states from a range of possible pain level values, possible signal characteristic values, and possible patient posture states, respectively, wherein each patient scenario comprises one or more predetermined parameter values that at least partially define the electrical stimulation; select a patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input, wherein each patient scenario of the plurality of patient scenarios comprises one or more predetermined parameters that at least partially define the electrical stimulation delivered to the patient; and adjust the one or more parameters to the one or more predetermined parameter values.

[0186] Example 10: The system of claim 9, wherein the processing circuit is further configured to adjust the one or more predetermined parameter values of one or more patient scenarios of the plurality of patient scenarios or the minimum stimulation amplitude based at least in part on the one or more second evoked electrical signals.

[0187] Example 11: The system of any of claims 9 and 10, wherein the processing circuit is configured to: determine a minimum stimulation amplitude for each of the plurality of patient scenarios; select the patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and based on the selected patient scenario, adjust the one or more parameters based on the minimum stimulation amplitude of the selected patient scenario.

[0188] Example 12: The system of any one of claims 1 to 11, wherein the patient input comprises first patient input, and wherein the processing circuit is further configured to: receive, via the one or more user devices, second patient input indicating that the patient is being affected by a medication; determine, based on the one or more second evoked electrical signals, an effect of the medication on the second signal characteristic; and adjust the one or more parameters based at least in part on the effect of the medication on the second signal characteristic.

[0189] Example 13: The system of claim 12, wherein the second signal characteristic comprises a nerve conduction velocity of the patient, and wherein the processing circuit is configured to determine an effect of the medication on the nerve conduction velocity of the patient.

[0190] Example 14: The system of any one of claims 1 to 13, wherein the processing circuit is further configured to: determine, based on the patient input, a level of comfort perceived by the patient; determine whether at least one of the one or more second evoked electrical signals satisfies a threshold condition corresponding to the level of comfort; and based on a determination that the at least one second evoked electrical signal satisfies the threshold condition, transmit, to the one or more user devices, a notification indicating that an electrical lead coupled with a medical device is displaced or damaged, wherein the medical device is configured to deliver the electrical stimulation to the patient during the posture state.

[0191] Example 15: The system of claim 14, wherein the threshold condition comprises a threshold evoked electrical signal amplitude for the determined level of comfort and the posture state.

[0192] Example 16: The system of any one of claims 1 to 15, wherein the processing circuit is further configured to: determine, based on the patient input, that the patient is experiencing pain; and determine, based on the second signal characteristic, whether a change in the one or more second evoked electrical signals relative to the one or more first evoked electrical signals corresponds to the pain experienced by the patient.

[0193] Example 17: The system of claim 16, wherein the processing circuit is further configured to: based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain, maintain the one or more parameters that at least partially define the electrical stimulation.

[0194] Example 18: The system of claim 16, wherein the processing circuit is further configured to: based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain, adjust the one or more parameters that at least partially define the electrical stimulation.

[0195] Example 19: The system of claim 18, wherein the processing circuit is configured to adjust the one or more parameters to a predetermined level based on determining that the change in the one or more second evoked electrical signals does not correspond to the pain, wherein the predetermined level is configured to reduce acute pain experienced by the patient.

[0196] Example 20: The system of any one of claims 1 to 19, wherein the first signal characteristic and the second signal characteristic each include a maximum amplitude of the one or more first evoked electrical signals and the one or more second evoked electrical signals, respectively.

[0197] Example 21 : The system of any one of claims 1 to 20, further comprising a stimulation generator configured to deliver electrical stimulation to the patient via one or more electrodes in electrical connection with the stimulation generator, and wherein the processing circuit is configured to control delivery of the electrical stimulation by controlling the one or more parameters that at least partially define the delivery of the electrical stimulation.

[0198] Example 22: A method comprising: receiving, by processing circuit of a medical device system, a first signal via sensing circuit of the medical device system, the first signal representing one or more first evoked electrical signals sensed from tissue of a patient and elicited by electrical stimulation delivered during a posture state of the patient; determining, by the processing circuit, a first signal characteristic of the one or more first evoked electrical signals for the posture state; receiving, by the processing circuit, patient input from one or more user devices, the patient input indicating a level of comfort of the patient associated with the one or more first evoked electrical signals during the posture state; determining, by the processing circuit, a target characteristic for the posture based on the first signal characteristic and the patient input; receiving, by the processing circuit via the sensing circuit, a second signal representing one or more second evoked electrical signals sensed from the tissue of the patient and elicited by the electrical stimulation delivered during the posture state; and controlling, by the processing circuit, one or more parameters based on a second signal characteristic of the one or more second evoked electrical signals and the target characteristic, the one or more parameters at least partially defining subsequent delivery of the electrical stimulation to the patient during the posture state.

[0199] Example 23: The method of claim 22, wherein at least one of the one or more first evoked electrical signals and the one or more second evoked electrical signals includes an evoked compound action potential (ECAP) signal.

[0200] Example 24: The method of any of claims 22 and 23, further comprising determining, by the processing circuit, a posture state of the patient based at least in part on a signal received from an accelerometer associated with the patient.

[0201] Example 25: The method of any of claims 22 to 24, wherein controlling the one or more parameters comprises: determining, by the processing circuit, whether a deviation of the second signal characteristic from the target characteristic reaches a threshold amount; and adjusting, by the processing circuit, the one or more parameters based on a determination that the deviation of the second signal characteristic from the target characteristic reaches the threshold amount.

[0202] Example 26: The method of claim 25, further comprising: sensing, by the processing circuit via the sensing circuit, a third signal representing one or more third evoked electrical signals sensed in the tissue and elicited by the subsequent delivery of the electrical stimulation; determining, by the processing circuit, a third signal characteristic of the third evoked electrical signals; determining, by the processing circuit, whether a deviation of the third signal characteristic from the target characteristic reaches the threshold amount; and based on a determination that the one or more third signal characteristics deviate from the target characteristic by less than the threshold amount, notifying, by the processing circuit via the one or more user devices, the patient that the electrical stimulation is within a target range.

[0203] Example 27: The method of any of claims 25 and 26, further comprising adjusting, by the processing circuit, the target characteristic of the posture state based at least in part on a second signal characteristic.

[0204] Example 28: The method of any of claims 22 to 27, wherein the patient input comprises a level of pain experienced by the patient with respect to the electrical stimulation, and wherein the method further comprises: determining, by the processing circuit, a correlation between the second signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters based at least in part on the correlation.

[0205] Example 29: The method of any of claims 22 to 28, wherein controlling the one or more parameters comprises: determining, by the processing circuit, a minimum stimulation amplitude for reducing pain experienced by the patient based on the first signal characteristic and the patient input; determining, by the processing circuit, one or more parameter values for the electrical stimulation based at least in part on the determined minimum amplitude; and adjusting, by the processing circuit, the one or more parameters of the electrical stimulation to the one or more parameter values.

[0206] Example 30: The method of any one of claims 28 and 29, further comprising: determining, by the processing circuit, a plurality of patient scenarios based on a plurality of combinations of one or more of pain level values, signal characteristic values, or patient posture states from a range of possible pain level values, possible signal characteristic values, and possible patient posture states, respectively, wherein each patient scenario comprises one or more predetermined parameter values that at least partially define the electrical stimulation; determining, by the processing circuit, a minimum stimulation amplitude for each of the plurality of patient scenarios; selecting, by the processing circuit, a patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters to the one or more predetermined parameter values.

[0207] Example 31 : The method of claim 30, further comprising adjusting, by the processing circuit, the one or more predetermined parameter values of one or more patient scenarios of the plurality of patient scenarios based at least in part on the second signal characteristic.

[0208] Example 32: The method of any one of claims 30 and 31, further comprising: determining, by the processing circuit, a minimum stimulation amplitude for each of the plurality of patient scenarios; selecting, by the processing circuit, the patient scenario of the plurality of patient scenarios based on the first signal characteristic and the patient input; and adjusting, by the processing circuit, the one or more parameters based on the minimum stimulation amplitude of the corresponding patient scenario.

[0209] Example 33: The method of any one of claims 22 to 32, wherein the patient input comprises a first patient input, and wherein the method further comprises receiving, by the processing circuit via the one or more user devices, a second patient input indicating that the patient is being affected by a medication; determining, by the processing circuit, an effect of the medication on the second signal characteristic based on the one or more second evoked electrical signals; and adjusting, by the processing circuit, the one or more based at least in part on the effect of the medication on the second signal characteristic.

[0210] Example 34: The method of claim 33, wherein the second signal characteristic comprises a nerve conduction velocity of the patient, and wherein the method further comprises: determining, by the processing circuit, an effect of the medication on the nerve conduction velocity of the patient.

[0211] Example 35: The method of any one of claims 22 to 34, further comprising: determining, by the processing circuit, a level of comfort perceived by the patient based on the patient input; determining, by the processing circuit, whether at least one of the one or more second evoked electrical signals satisfies a threshold condition corresponding to the level of comfort; and based on a determination that the at least one second evoked electrical signal satisfies the threshold condition, transmitting, by the processing circuit to the patient via the one or more user devices, a notification indicating one or more of: a possible dislodgement of an electrical lead, or a possible damage to at least one electrode of one or more electrodes disposed on the electrical lead.

[0212] Example 36: The method of claim 35, wherein the threshold condition comprises a threshold sensed evoked electrical signal amplitude for the determined level of comfort and the posture state by the patient.

[0213] Example 37: The method of any one of claims 22 to 36, further comprising: determining, by the processing circuit, that the patient is experiencing pain based on the patient input; and determining, by the processing circuit, whether a change in the one or more second evoked electrical signals relative to the one or more first evoked electrical signals corresponds to the pain experienced by the patient based on the second signal characteristic.

[0214] Example 38: The method of claim 37, further comprising maintaining, by the processing circuit, the one or more parameters based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain.

[0215] Example 39: The method of claim 37, further comprising adjusting, by the processing circuit, the one or more parameters based on a determination that the change in the one or more second evoked electrical signals does not correspond to the pain.

[0216] Example 40: The method of claim 39, further comprising adjusting, by the processing circuit, the one or more parameters of the electrical stimulation to one or more predetermined values based on the determination that the change in the one or more second evoked electrical signals does not correspond to the pain, wherein the one or more predetermined values are configured to mitigate acute pain experienced by the patient.

[0217] Example 41: The method of any one of claims 22 to 40, wherein the first signal characteristic and the second signal characteristic each comprise a maximum amplitude of the one or more first evoked electrical signals and the one or more second evoked electrical signals, respectively.

[0218] Example 42: A computer-readable medium comprising instructions that, when executed, cause a processing circuit of an implantable medical device system to perform the method of any of claims 22-41.

[0219] Various different examples have been described. These and other examples fall within the scope of the following claims.

Claims

1. A system comprising: Processing circuit, the processing circuit being configured to: The system receives a first signal via its sensing circuitry, the first signal representing one or more first evoked signals sensed from the patient’s tissues and triggered by electrical stimulation delivered during the patient’s postural state; A first signal characteristic of the one or more first evoked signals that determine the posture state; Patient input is received via one or more user devices of the system, the patient input indicating the patient's comfort level associated with the one or more first evoked signals during the postural state; The target characteristics of the posture state are determined based on the first signal characteristics and the patient input. A second signal is received via the sensing circuit, the second signal representing one or more second evoked signals sensed from the patient's tissue and triggered by the electrical stimulation delivered during the postural state; and One or more parameters are controlled based on the second signal characteristics of the one or more second evoked signals and the target characteristics, the one or more parameters being at least partially defined in the subsequent delivery of the electrical stimulation to the patient during the postural state.

2. The system as claimed in claim 1, wherein, At least one of the one or more first evoked signals and the one or more second evoked signals includes an evoked compound action potential (ECAP) signal.

3. The system as described in any one of claims 1 and 2, wherein, The processing circuitry is further configured to determine the patient’s posture state based at least in part on signals received from an accelerometer associated with the patient.

4. The system as described in any one of claims 1 to 3, wherein, In order to control the one or more parameters, the processing circuit is further configured to: Determine whether the deviation between the second signal characteristic and the target characteristic reaches a threshold value; and Based on the determination that the deviation between the second signal characteristic and the target characteristic reaches the threshold amount, one or more parameters are adjusted.

5. The system as described in claim 4, wherein, The processing circuit is further configured to: A third signal is sensed via the sensing circuit, the third signal representing one or more third evoked signals sensed in the tissue and triggered by the subsequent delivery of the electrical stimulation; Determine the third signal characteristics of the third induced electrical signal; Determine whether the deviation between the third signal characteristic and the target characteristic reaches the threshold amount; and Based on the determination that the deviation between the third signal characteristic and the target characteristic is less than the threshold amount, the one or more user devices are notified that the electrical stimulation is within the target range.

6. The system as described in any one of claims 4 and 5, wherein, The processing circuitry is further configured to adjust the target characteristic of the posture state based at least in part on the second signal characteristic.

7. The system as claimed in any one of claims 1 to 6, wherein, The patient input includes the level of pain experienced by the patient in response to the electrical stimulation, and wherein the processing circuitry is further configured to: Determine the correlation between the second signal characteristic and the patient input; and The one or more parameters are adjusted based at least in part on the correlation.

8. The system as claimed in any one of claims 1 to 7, wherein, In order to control the one or more parameters, the processing circuit is configured to: The minimum stimulus amplitude for alleviating the pain experienced by the patient is determined based on the first signal characteristics and the patient input. One or more parameter values ​​of the electrical stimulation are determined at least in part based on the determined minimum amplitude; and Adjust one or more parameters of the electrical stimulation to the one or more parameter values.

9. The system as described in any one of claims 7 and 8, wherein, The processing circuit is configured as follows: Multiple patient scenarios are determined based on multiple combinations of one or more of a series of possible pain level values, possible signal characteristic values, and possible patient postural states, wherein each patient scenario includes one or more predetermined parameter values ​​that at least partially define the electrical stimulation. The patient scenario is selected from the plurality of patient scenarios based on the first signal characteristics and the patient input, wherein each of the plurality of patient scenarios includes one or more predetermined parameters that at least partially define the electrical stimulation delivered to the patient; and Adjust the one or more parameters to the one or more predetermined parameter values.

10. The system of claim 9, wherein, The processing circuitry is further configured to adjust the one or more predetermined parameter values ​​or the minimum stimulation amplitude of one or more of the plurality of patient scenarios based at least in part on the one or more second evoked signals.

11. The system as claimed in any one of claims 9 and 10, wherein, The processing circuit is configured as follows: Determine the minimum stimulus amplitude for each of the plurality of patient scenarios; The patient scenario is selected from the plurality of patient scenarios based on the first signal characteristics and the patient input. and Based on the selected patient scenario, one or more parameters are adjusted based on the minimum stimulus amplitude of the selected patient scenario.

12. The system as claimed in any one of claims 1 to 11, wherein, The patient input includes a first patient input, and wherein the processing circuit is further configured to: Receive second patient input via the one or more user devices, indicating that the patient is being affected by medication; The effect of the drug on the second signal characteristics is determined based on the one or more second evoked signals; and The one or more parameters are adjusted based at least in part on the effect of the drug on the second signal characteristic.

13. The system of claim 12, wherein, The second signal characteristic includes the patient's nerve conduction velocity, and wherein the processing circuit is configured to determine the effect of the drug on the patient's nerve conduction velocity.

14. The system as claimed in any one of claims 1 to 13, wherein, The processing circuit is further configured to: The patient's perceived level of comfort is determined based on the patient's input; Determine whether at least one of the one or more second evoked signals satisfies a threshold condition corresponding to the comfort level; and Based on determining that the at least one second evoked signal satisfies the threshold condition, a notification indicating that the electrical lead coupled to the medical device has been displaced or damaged is transmitted to the one or more user devices, wherein the medical device is configured to deliver the electrical stimulation to the patient during the posture state.

15. The system of any one of claims 1 to 14, further comprising a stimulation generator configured to deliver electrical stimulation to the patient via one or more electrodes electrically connected to the stimulation generator, and wherein, The processing circuitry is configured to control the delivery of the electrical stimulation by controlling one or more parameters that at least partially define the delivery of the electrical stimulation.

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