Multi-site mixed neuromodulation control

Abstract

Devices, systems, or methods are configured to deliver open-loop electrical stimulation together with closed-loop stimulation. For example, processing circuitry is configured to receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window and control, based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes. The processing circuitry may also be configured to control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open- loop electrical stimulation.

Description

Docket No.: A0013641W001MULTI-SITE MIXED NEUROMODULATION CONTROLCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 748,330, filed January 22, 2025, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure generally relates to medical devices, and more specifically, electrical stimulation.BACKGROUND

[0003] Medical devices may be external or implanted and may be used to deliver electrical stimulation therapy to patients 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. A medical device may deliver electrical stimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Stimulation proximate the spinal cord, proximate the sacral nerve, within the brain, and proximate peripheral nerves are often referred to as spinal cord stimulation (SCS), sacral neuromodulation (SNM), deep brain stimulation (DBS), and peripheral nerve stimulation (PNS), respectively.SUMMARY

[0004] In general, the disclosure is directed to devices, systems, and techniques for providing various therapies to a patient (e.g., pain relief therapy) by using mixed delivery of open-loop and closed-loop stimulation at different respective tissue sites. For example, a system may be configured to deliver open-loop electrical stimulation via one or more electrode combinations and closed-loop electrical stimulation via one or more different electrode combinations. Open-loop electrical stimulation (or static stimulation) refers to one or more trains of electrical stimulation pulses that are delivered according to a set of stimulation parameter values that are not changed in response to any sensed signals. In contrast, closed-loop electrical stimulation (or dynamic stimulation) refers to one or moreDocket No.: A0013641W001trains of electrical stimulation pulses defined by one or more stimulation parameters that can be adjusted in response to a sensed signal.

[0005] The system can at least partially interleave pulses of the open-loop electrical stimulation with at least some pulses of the closed-loop electrical stimulation while preventing open-loop electrical stimulation pulses from interfering with closed-loop electrical stimulation pulses and / or a sensing window within which a physiological signal is configured to be sensed. For example, the sensing window may be configured to have a duration that enables sensing of an evoked signal (e.g., an evoked compound action potential (ECAP)) elicited by a pulse of the closed-loop electrical stimulation. The system can withhold any pulses of the open-loop electrical stimulation pulse train, modify one or more pulses of the open-loop electrical pulse train, or even disable open-loop electrical stimulation delivery in order to prevent interference with the closed-loop electrical stimulation or the sensing of the evoked signal. The closed-loop electrical stimulation may be delivered to a neural target within the central nervous system (e.g., a spinal cord or brain), and the open-loop electrical stimulation may be delivered to a dorsal root ganglion (DRG) or peripheral nerve (e.g., sacral nerve, tibial nerve, etc.).

[0006] In one example, this disclosure describes a system including: processing circuitry configured to: receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window; control, based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open-loop electrical stimulation.

[0007] In another example, this disclosure describes a method including: receiving, by processing circuitry and from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window; controlling, by the processing circuitry and based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; controlling, by the processing circuitry, the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglionDocket No.: A0013641W001or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the openloop electrical stimulation.

[0008] In another example, this disclosure describes computer-readable storage medium including instructions that, when executed, cause the processing circuitry to: receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window; control, based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; and control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open-loop electrical stimulation.

[0009] The summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, device, and methods described in detail within the accompanying drawings and description below. Further details of one or more examples of this disclosure 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

[0010] FIG. 1A is a conceptual diagram illustrating an example system that includes an implantable medical device (IMD) configured to deliver closed-loop stimulation together with open-loop stimulation, in accordance with one or more techniques of this disclosure.

[0011] FIG. IB is a conceptual diagram illustrating an example system that includes an implantable medical device (IMD) configured to deliver closed-loop stimulation to a spinal cord and open-loop stimulation to a peripheral nerve, such as a sacral nerve, in accordance with one or more techniques of this disclosure.Docket No.: A0013641W001

[0012] FIG. 2 is a block diagram illustrating an example configuration of components of an IMD, in accordance with one or more techniques of this disclosure.

[0013] FIG. 3 is a block diagram illustrating an example configuration of components of an external programmer, in accordance with one or more techniques of this disclosure.

[0014] FIG. 4 is a timing diagram illustrating an example of delivering open-loop electrical stimulation pulses together with closed-loop electrical stimulation and associated sensing windows.

[0015] FIGS. 5 A and 5B are timing diagrams illustrating an example of delivering open-loop electrical stimulation pulses together with closed-loop electrical stimulation and associated sensing windows.

[0016] FIG. 6 is a flow diagram illustrating an example technique for delivering open-loop electrical stimulation pulses outside of sensing windows associated with closed-loop electrical stimulation pulses.

[0017] FIG. 7 is a conceptual diagram of an example user interface that enables a user to enable or disable closed-loop stimulation for a stimulation program.

[0018] FIG. 8 is a conceptual diagram of an example user interface that displays groups of respective stimulation programs and an indication of which programs are closed-loop stimulation enabled or disabled.

[0019] Like reference characters denote like elements throughout the description and figures.DETAILED DESCRIPTION

[0020] The disclosure describes examples of medical devices, systems, and techniques for providing various therapy to a patient (e.g., pain relief therapy) by using mixed delivery of open-loop and closed-loop stimulation at different respective tissue sites. Clinical benefit may be realized by the simultaneous application of neuromodulation to multiple targets. For instance, spinal cord stimulation (SCS) can be combined with dorsal root ganglion stimulation (DRG-S). In one example, one lead may be positions with electrodes placed over an L3 / L4 DRG and a second lead is placed over a dorsal column of the spinal cord at L1 / L2. Alternatively, SCS can be combined with peripheral nerve stimulation (PNS) (e.g., sacral nerve stimulation, tibial nerve stimulation, vagus nerve stimulation, etc.).Docket No.: A0013641W001

[0021] There are different programming considerations for both SCS and PNS / DRG-S. With SCS, stimulation energy is generally delivered through the cerebrospinal fluid (CSF) to the mobile spinal cord. Since the spinal cord is mobile, or can move within the CSF, there is variable delivery of the stimulation energy as the cord moves. In other words, the distance between electrodes and spinal cord can change with patient movement. However, this is not the case with DRG-S and PNS as the orientation of the neural target with respect to the stimulating electrodes is substantially fixed. Put another way, little postural sensitivity exists with DRG-S. Due to these physiological differences in neural targets, SCS can benefit from closed-loop stimulation (e.g., ECAP-controlled stimulation), while DRG-S or PNS may not benefit from closed-loop control. In this manner, DRG-S or PNS can be delivered via open-loop electrical stimulation that does not change stimulation parameter values. Although open-loop electrical stimulation can thus be delivered to one neural target while closed-loop electrical stimulation can be delivered to a second different neural target, the open-loop electrical stimulation should not interfere with any sensing or associated closed-loop control.

[0022] As described herein, systems, devices, and techniques provide for delivering both multi-site, open-loop neuromodulation (electrical stimulation) together with closed-loop neuromodulation so that the open-loop neuromodulation does not interfere with aspects of the closed-loop control of the closed-loop neuromodulation (e.g., biopotential sensing of the system). Possible neural targets for the closed-loop neuromodulation can be within the central nervous system (CNS), such as the dorsal columns or the anterior nucleus of the thalamus. Possible targets for open-loop neuromodulation can be neural targets at or near the DRG or in the peripheral nervous system (e.g., sacral nerve, pudendal nerve, tibial nerve, etc.).

[0023] Open-loop electrical stimulation (or static stimulation) refers to one or more trains of electrical stimulation pulses that are delivered according to a set of stimulation parameter values that are not changed in response to any sensed signals. In contrast, closed-loop electrical stimulation (or dynamic stimulation) refers to one or more trains of electrical stimulation pulses defined by one or more stimulation parameters that can be adjusted in response to a sensed signal.

[0024] The system can at least partially or fully interleave pulses of the open-loop electrical stimulation with at least some pulses of the closed-loop electrical stimulation while preventing open-loop electrical stimulation pulses from interfering with closed-loopDocket No.: A0013641W001electrical stimulation pulses and / or a sensing window within which a physiological signal is configured to be sensed. This interleaving of pulses from the different trains of open and closed-loop stimulation can provide the sensation of simultaneous therapy to the different respective neural targets of the patient. In sone examples, the sensing window may be configured to have a duration that enables sensing of an evoked signal (e.g., an ECAP) elicited by a pulse of the closed-loop electrical stimulation. The system can withhold any pulses of the open-loop electrical stimulation pulse train, modify one or more pulses of the open-loop electrical pulse train, or even disable open-loop electrical stimulation delivery in order to prevent interference with the closed-loop electrical stimulation. In some examples, the system may include a user interface that enables a user to turn closed-loop stimulation on or off, which may change how the open-loop stimulation can be delivered.

[0025] The delivery of both closed-loop stimulation together with open-loop stimulation as described herein can provide various advantages. For example, the system can provide open-loop stimulation together with closed-loop stimulation by removing one or more pulses, or modifying one or more pulses, of the open-loop stimulation to avoid disruption of sensing physiological signals needed for closed-loop control. This dynamic adjustment to therapy can enable the system to provide closed-loop control to appropriate neural targets, such as the spinal cord, while also providing stimulation to other neural targets that may otherwise interfere with sensing physiological signals. In addition, the system may automatically perform adjustments to therapy without requiring the user to ensure that different pulse trains do not interfere with each other. According to these techniques, open-loop and closed-loop stimulation can be delivered from the same IMD or different IMDs as needed.

[0026] Although electrical stimulation is generally described herein in the form of electrical stimulation pulses, electrical stimulation may be delivered in non-pulse form in other examples. For example, electrical stimulation may be delivered as a signal having various waveform shapes, frequencies, and amplitudes. Therefore, electrical stimulation in the form of a non-pulse signal may be a continuous signal than may have a sinusoidal waveform or other continuous waveform.

[0027] FIG. 1A is a conceptual diagram illustrating an example system 100 that includes an implantable medical device (IMD) configured to deliver closed-loop stimulation together with open-loop stimulation, in accordance with one or moreDocket No.: A0013641W001techniques of this disclosure. In the example of FIG. 1A, system 100 can deliver closed-loop stimulation to one neural target, such as a portion of a dorsal column of spinal cord 120, and open-loop stimulation to another neural target such as DRG 125 that extends from spinal cord 120. Although the techniques described in this disclosure are generally applicable to a variety of medical devices including external devices and IMDs, application of such techniques to IMDs and, more particularly, implantable electrical stimulators (e.g., neurostimulators) will be described for purposes of illustration. More particularly, the disclosure will refer to implantable SCS and PNS systems for purposes of illustration, but without limitation as to other types of medical devices or other therapeutic applications of medical devices.

[0028] As shown in FIG. 1A, system 100 includes an IMD 114, leads 130A and 130B, and external programmer 150 shown in conjunction with a patient 105, who is ordinarily a human patient. In the example of FIG. 1 A, IMD 114 is an implantable electrical stimulator that is configured to generate and deliver electrical stimulation therapy to patient 105 via one or more electrodes of electrodes of leads 130A and / or 130B (collectively, “leads 130”), e.g., for relief of chronic pain or other symptoms. In other examples, IMD 114 may be coupled to a single lead carrying multiple electrodes or more than two leads each carrying multiple electrodes, such that different electrode configurations can treat different neural targets as described herein. IMD 114 may be a chronic electrical stimulator that remains implanted within patient 105 for weeks, months, or even years. In other examples, IMD 114 may be a temporary, or trial, stimulator used to screen or evaluate the efficacy of electrical stimulation for chronic therapy. In one example, IMD 114 is implanted within patient 105, while in another example, IMD 114 is an external device coupled to percutaneously implanted leads.

[0029] IMD 114 may be constructed of any polymer, metal, or composite material sufficient to house the components of IMD 114 (e.g., components illustrated in FIG. 2) within patient 105. In this example, IMD 114 may be constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material such as silicone, polyurethane, or a liquid crystal polymer, and surgically implanted at a site in patient 105 near the pelvis, abdomen, or buttocks. In other examples, IMD 114 may be implanted within other suitable sites within patient 105, which may depend, for example, on the target site within patient 105 for the delivery of electrical stimulation therapy. The outer housing of IMD 114 may be configured to provide a hermetic seal for components, suchDocket No.: A0013641W001as a rechargeable or non-rechargeable power source. In addition, in some examples, the outer housing of IMD 114 is selected from a material that facilitates receiving energy to charge the rechargeable power source.

[0030] Electrical stimulation energy, which may be constant current or constant voltage-based pulses, for example, is delivered from IMD 114 to one or more target tissue sites of patient 105 via one or more electrodes (not shown) of implantable leads 130. In the example of FIG. 1A, lead 130A carries electrodes 132 that are placed adjacent to the target tissue of spinal cord 120. In some examples, lead BOB carries electrodes 134 that are placed adjacent to target tissue near DRG 125 which leads to respective peripheral nerves. Spinal cord 120 runs through vertebra 122, and DRG 125 is just one DRG of many DRG that extend from respective locations of spinal cord 120 and out of respective vertebra 122. As shown in FIG. 1A, the distal end of lead BOB may be curved in order to place at least some of electrodes 134 along the length of at least a portion of DRG 134. In other examples, other neural sites may be selected for stimulation delivery, such as different locations of spinal cord 120, placing electrodes 134 to target one or more peripheral nerves, etc.

[0031] One or more of the electrodes 132,134 may be disposed at a distal tip of a lead 130 and / or at other positions at intermediate points along the lead. Leads 130 may be implanted and coupled to IMD 114. The electrodes may transfer electrical stimulation generated by an electrical stimulation generator in IMD 114 to tissue of patient 105. Although leads 130 may each be a single lead, lead 130 may include a lead extension or other segments that may aid in implantation or positioning of lead 130. In some other examples, IMD 114 may be a leadless stimulator with one or more arrays of electrodes arranged on a housing of the stimulator rather than leads that extend from the housing. In addition, in some other examples, system 100 may include one lead or more than two leads, each coupled to IMD 114 and directed to similar or different target tissue sites.

[0032] The electrodes of leads 130 may be electrode pads on a paddle lead, circular (e.g., ring) electrodes surrounding the body of the lead, conformable electrodes, cuff electrodes, segmented electrodes (e.g., electrodes disposed at different circumferential positions around the lead instead of a continuous ring electrode), any combination thereof (e.g., ring electrodes and segmented electrodes) or any other type of electrodes capable of forming unipolar, bipolar or multipolar electrode combinations for therapy. RingDocket No.: A0013641W001electrodes arranged at different axial positions at the distal ends of lead 130 will be described for purposes of illustration.

[0033] The deployment of electrodes via leads 130 is described for purposes of illustration, but arrays of electrodes may be deployed in different ways. For example, a housing associated with a leadless stimulator may carry arrays of electrodes, e.g., rows and / or columns (or other patterns), to which shifting operations may be applied. Such electrodes may be arranged as surface electrodes, ring electrodes, or protrusions. As a further alternative, electrode arrays may be formed by rows and / or columns of electrodes on one or more paddle leads. In some examples, electrode arrays include electrode segments, which are arranged at respective positions around a periphery of a lead, e.g., arranged in the form of one or more segmented rings around a circumference of a cylindrical lead. In other examples, one or more of leads 130 are linear leads having 8 ring electrodes along the axial length of the lead. In another example, the electrodes are segmented rings arranged in a linear fashion along the axial length of the lead and at the periphery of the lead.

[0034] The stimulation parameter of a therapy stimulation program that defines the stimulation pulses of electrical stimulation therapy by IMD 114 through the electrodes of leads 130 may include information identifying which electrodes have been selected for delivery of stimulation according to a stimulation program, the polarities of the selected electrodes, i.e., the electrode combination for the program, and voltage or current amplitude, pulse frequency, pulse width, pulse shape of stimulation delivered by the electrodes. These stimulation parameters of stimulation pulses are typically predetermined parameter values determined prior to delivery of the stimulation pulses (e.g., set according to a stimulation program). However, in some examples, system 100 changes one or more parameter values automatically based on one or more factors or based on user input.

[0035] As described herein, IMD 114 is configured to deliver stimulation to different neural target sites, and may be configured to deliver closed-loop stimulation to one neural site and open-loop stimulation to a different neural target. As shown in FIG. 1A, IMD 114 may deliver closed-loop stimulation to a portion of spinal cord 120 via one or more electrode combinations of electrodes 132. A sensing electrode combination from electrodes 132 and / or electrodes of another lead may sense a physiological signal from patient 105. The physiological signal may be an electrical signal (e.g., local fieldDocket No.: A0013641W001potentials or an evoked signal such as an ECAP). For evoked signals or some other physiological signal types, IMD 114 may be configured to sense the physiological signal during a sensing window that may follow a delivered stimulation pulse of the closed-loop stimulation or another type of stimulation pulse. IMD 114 may deliver the open-loop stimulation to a portion of DRG 125 via an electrode combination of electrodes 134, and IMD 114 may control delivery of pulses of the open-loop stimulation to avoid overlapping with at least a portion of the sensing window, time before and / or after the sensing window, and / or a stimulation pulse of the closed-loop stimulation. In this manner, IMD 114 may control stimulation circuitry to deliver both the closed-loop stimulation and the open-loop stimulation and sense physiological signals used to adjust the closed-loop stimulation. IMD 114 may have a housing (e.g., a sealed case that may be configured to accept one or more medical leads) that encloses stimulation circuitry, sensing circuitry, processing circuitry, and possibly other components.

[0036] Although a single IMD 114 is shown, other examples can include two or more different and separate IMDs that deliver the respective closed-loop stimulation and openloop stimulation. With two or more IMDs, a first IMD may include a first housing that encloses a first portion of stimulation circuitry configured to deliver the closed-loop electrical stimulation, and a second IMD different from the first IMD, where the second IMD includes a second housing that encloses a second portion of the stimulation circuitry configured to deliver the open-loop electrical stimulation. One or more of the IMDs may send and / or receive commands that are configured to control the timing of stimulation delivery from each IMD.

[0037] In general, IMD 114 is configured to deliver neuromodulation to at least two different targets (e.g., spinal cord 120 and DRG 125), of which one has comparatively variable physical separation of about 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or more than 3 mm between the stimulating electrodes and the target. This variable physical separation, which may occur at neural sites, can occur with activities of daily living or postural shifts. In the example of spinal cord 120, the patient movement can cause the electrodes in the epidural space to float further, or closer, to spinal cord 120.

[0038] IMD 114 may employ closed-loop control of neuromodulation to adapt the stimulation charge and / or phase delivered to the neural target for which there is variable separation with respect to the stimulating electrode. To provide closed-loop stimulation, IMD 114 may sense one or more physiological signals indicative of the variableDocket No.: A0013641W001separation and adjust one or more stimulation parameters that define electrical stimulation to compensate for the change in separation of electrodes to neural target. In some examples, the closed-loop controller of IMD 114 can be configured to sense the physiological signal (e.g., a biopotential such as an ECAP) that may be elicited from a stimulation pulse. The biopotential may be detectable at about 0.5 ms, 1.0 ms, 1.5 ms, 2.0 ms, 2.5 ms, 3.0 ms, 3.5 ms, 4.0 ms. 4.5 ms, or 5.0 ms after the stimulation pulse is delivered. IMD 114 may establish a sensing window that corresponds to the expected arrival of the biopotential for sensing. In this manner, the sensing window may be set to have a duration from 0.5 ms to 6 ms (or longer) from delivery of the stimulation pulse expected to elicit the biopotential.

[0039] Pulses of the closed-loop neuromodulation may be biphasic and may include active or passive recharge recovery phases. In some examples, the pulse frequency of the closed-loop neuromodulation is from 2 Hz to 250 Hz. In one examples, the pulse frequency is about 50 Hz. The pulse width of the closed-loop neuromodulation may be from 60 ps to 500 ps. In some examples, the pulse width may be about 200 ps. The pulse amplitude of the closed-loop neuromodulation may be from 0.5 mA to 25.5 mA. In one example, the pulse amplitude may be about 4 mA, but the pulse amplitude (or other parameter) may be adjusted by the user and / or automatically according to the closed-loop instructions. In some examples, the nominal charge / phase of the closed-loop neuromodulation is about 800 nanocoulombs (nC) (4 mA * 200 ps), but that charge / phase may be adjusted or customized for individual patients. In some examples, IMD 114 may be configured to adjust one or more parameters defining the closed-loop stimulation pulses in order to maintain a target charge or target charge window. IMD 114 may be configured to deliver the pulse trains of the closed-loop stimulation to a neural target in the CNS, such as the dorsal columns of the spinal cord 120, the anterior nucleus of the thalamus, or the sub-thalamic nucleus, but other neural targets may also be used.

[0040] IMD 114 may be configured to partially, or fully, interleave one or more pulses of the open-loop stimulation with at least some of the pulses of the closed-loop stimulation. Full interleaving may refer to alternating between pulses from the closed-loop stimulation and the open-loop stimulation. Partial interleaving may include multiple pulses from one type of stimulation (e.g., multiple open-loop stimulation pulses) between consecutive stimulation pulses from the other type of stimulation (e.g., closed-loop stimulation pulses). The open-loop stimulation pulses may have passive recharge phasesDocket No.: A0013641W001and / or active recharge phases. Since active recharge phases can be completed in less time, IMD 114 may select active recharge phases for open-loop stimulation in order to fit the pulses in available time between closed-loop stimulation pulses and / or sensing windows. In some examples, IMD 114 may only deliver some open-loop stimulation pulses with active recharge on an as-needed basis in order to avoid interference with closed-loop stimulation pulses and / or sensing windows. In some examples, IMD 114 may select active or passive recharge phase based on the delivered charge and time necessary for passive recharge to clear residual charge at the electrodes. In addition, IMD 114 may use passive or active recharge phases for closed-loop stimulation as needed. For example, IMD 114 may use active recharge phase for a closed-loop stimulation pulse configured to elicit an ECAP signal in order to use a shorter sensing window.

[0041] In some examples, IMD 114 may deliver the open-loop neuromodulation pulses on, over, or at a proximal or distal process of a DRG, such as DRG 125. In addition, or alternatively, IMD 114 may deliver the open-loop neuromodulation pulses to one or more a peripheral nerves. IMD 114 may prevent any pulses from the open-loop stimulation pulse from being delivered within the sensing window, or interval, that the biopotential used by the closed-loop controller is being sensed. In some examples, IMD 114 may also prevent any pulses from the open-loop stimulation from being delivered within a pre-pulse window immediately preceding the start of a closed-loop stimulation pulse. This pre-pulse window may have a duration from 0.5 ms to 3 ms, or 1 ms in some examples. By preventing open-loop stimulation pulses from being delivered within the pre-pulse window, the biopotential sensed (e.g., an ECAP signal) may not be impacted by any prior pulse.

[0042] IMD 114 may control the charge or phase of the open-loop stimulation pulses. In some examples, the maximum charge / phase of the open-loop neuromodulation is less than that of the closed-loop neuromodulation. Put another way, the overall charge, or intensity, of the open-loop stimulation pulses may be less than the closed-loop stimulation. This reduced charge may be due to closed proximity of electrodes to the DRG or peripheral nerves than in the spinal cord or the different nerve fibers intended to be innervated.

[0043] In some examples, IMD 114 may determine to withhold all pulses of the openloop stimulation if no pulses, or a threshold minimum number or frequency of pulses, can be delivered without interfering with closed-loop stimulation and / or sensing. ForDocket No.: A0013641W001example, if the period of the closed-loop neuromodulation is too narrow (e.g., the interpulse phase is too short) to allow opportunity for a pulse, or certain number of pulses, of the open loop neuromodulation to be delivered, then IMD 114 can disable the open-loop neuromodulation. This disabling may be referred to as “locking out” open-loop stimulation. In one example, if the open-loop stimulation frequency is 200 Hz, but the total keepout window (e.g., sensing window and pre-pulse window) is 5 ms or more, no pulses of the open-loop stimulation can fit with those parameters and IMD 114 may disable the open-loop stimulation.

[0044] Although FIG. 1A is directed to a combination of stimulation delivered to the spinal cord and DRG(s), e.g., used to treat pain, in other examples system 100 may be configured to treat any other condition that may benefit from electrical stimulation therapy. For example, system 100 may be used to treat tremor, Parkinson’s disease, epilepsy, a pelvic floor disorder (e.g., urinary incontinence or other bladder dysfunction, fecal incontinence, pelvic pain, bowel dysfunction, or sexual dysfunction), obesity, gastroparesis, or psychiatric disorders (e.g., depression, mania, obsessive compulsive disorder, anxiety disorders, and the like). In this manner, system 100 may be configured to provide therapy taking 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 105. For example, for PNFS, one of the leads 130 is disposed along the spinal cord 120, and one of the leads is disposed along one or more peripheral nerves at respective locations.

[0045] In some examples, leads 130 includes one or more sensors configured to allow IMD 114 to monitor one or more parameters of patient 105, such as patient activity, pressure, temperature, or other characteristics. The one or more sensors may be provided in addition to, or in place of, therapy delivery by leads 130.

[0046] IMD 114 is configured to deliver electrical stimulation therapy to patient 105 via selected combinations of electrodes carried by one or both of leads 130, alone or in combination with an electrode carried by or defined by an outer housing of IMD 114. The target tissue for the electrical stimulation therapy may be any tissue affected by electrical stimulation, which may be in the form of electrical stimulation pulses or continuous waveforms and may include a first target tissue and a second target tissue. In some examples, the target tissue includes nerves, smooth muscle or skeletal muscle, orDocket No.: A0013641W001peripheral nerves. In the example illustrated by FIG. 1A, a first target tissue is tissue proximate spinal cord 120 or tissue associated with spinal cord 120, such as within an intrathecal space or epidural space of spinal cord 120, or, in some examples, adjacent nerves that branch off spinal cord 120. The second target tissue is one or more DRGs 125 in this example. Leads 130 may be introduced into adjacent spinal cord 120 in via any suitable region, such as the thoracic, cervical or lumbar regions. Stimulation of spinal cord 120 may, for example, prevent pain signals from traveling through spinal cord 120 and to the brain of patient 105. Patient 105 may perceive the interruption of pain signals as a reduction in pain and, therefore, efficacious therapy results. In other examples, stimulation of spinal cord 120 may produce paresthesia which may be reduce the perception of pain by patient 105, and thus, provide efficacious therapy results.

[0047] IMD 114 generates and delivers electrical stimulation therapy to a target stimulation site within patient 105 via the electrodes of leads 130 to patient 105 according to one or more therapy stimulation programs. A therapy stimulation program defines values for one or more parameters that define an aspect of the therapy delivered by IMD 114 according to that program. For example, a therapy stimulation program that controls delivery of stimulation by IMD 114 in the form of pulses may define values for voltage or current pulse amplitude, pulse width, and pulse rate (e.g., pulse frequency) for stimulation pulses delivered by IMD 114 according to that program.

[0048] A user, such as a clinician or patient 105, may interact with a user interface of an external programmer 150 to program IMD 114. Programming of IMD 114 may refer generally to the generation and transfer of commands, programs, or other information to control the operation of IMD 114. In this manner, IMD 114 may receive the transferred commands and programs from external programmer 150 to control electrical stimulation therapy. For example, external programmer 150 may transmit therapy stimulation programs, stimulation parameter adjustments, therapy stimulation program selections, user input, or other information to control the operation of IMD 114, e.g., by wireless telemetry or wired connection. As described herein, stimulation delivered to the patient may include control pulses, and, in some examples, stimulation may include control pulses and informed pulses.

[0049] In some cases, external programmer 150 may be characterized as a physician or clinician programmer if it is primarily intended for use by a physician or clinician. In other cases, external programmer 150 may be characterized as a patient programmer if itDocket No.: A0013641W001is primarily intended for use by a patient. A patient programmer may be generally accessible to patient 105 and, in many cases, may be a portable device that may accompany patient 105 throughout the patient’s daily routine. For example, a patient programmer may receive input from patient 105 when the patient wishes to terminate or change electrical stimulation therapy. In general, a physician or clinician programmer may support selection and generation of programs by a clinician for use by IMD 114, whereas a patient programmer may support adjustment and selection of such programs by a patient during ordinary use. In other examples, external programmer 150 may include, or be part of, an external charging device that recharges a power source of IMD 114. In this manner, a user may program and charge IMD 114 using one device, or multiple devices.

[0050] As described herein, information may be transmitted between external programmer 150 and IMD 114. Therefore, IMD 114 and external programmer 150 may communicate via wireless communication using any techniques known in the art.Examples of communication techniques may include, for example, radiofrequency (RF) telemetry and inductive coupling, but other techniques are also contemplated. In some examples, external programmer 150 includes a communication head that may be placed proximate to the patient’s body near the IMD 114 implant site to improve the quality or security of communication between IMD 114 and external programmer 150.Communication between external programmer 150 and IMD 114 may occur during power transmission or separate from power transmission.

[0051] In some examples, IMD 114, in response to commands from external programmer 150, delivers electrical stimulation therapy according to a plurality of therapy stimulation programs to a target tissue site of the spinal cord 120 of patient 105 via electrodes (not depicted) on leads 130, and to a target tissue site of DRG 125. In some examples, IMD 114 modifies therapy stimulation programs as therapy needs of patient 105 evolve over time. For example, the modification of the therapy stimulation programs may cause the adjustment of at least one parameter of the plurality of informed pulses. When patient 105 receives the same therapy for an extended period, the efficacy of the therapy may be reduced. In some cases, parameters of the plurality of informed pulses may be automatically updated.

[0052] In the example of a single device coupled to leads disposed at different locations, the timing of the delivery of the stimulus and the detection of a biopotential,Docket No.: A0013641W001(e.g., an ECAP), such as detection of the ECAP at the lead different than the lead that delivered the stimulus, may be fixed based on the known distances along the leads. In other examples of a single device or multiple devices coupled to respective leads at different locations, one or both devices may communicate to determine the time required for the ECAP signal to propagate to the sensing location from the stimulus location. Then, the single device or multiple devices may coordinate delivery of the stimulus from one lead and the sensing window at the other lead in order to improve detection of the ECAP signal. This timing can be set initially or periodically over time if conduction changes or other issues occur. Example peripheral nerves include, but are not limited to, sacral nerve, tibial nerve, pudendal nerve, sciatic nerve, cluneal nerve, genicular nerve, occipital nerve, ulnar or radial nerve, or the dorsal rami of any spinal nerve. Other nerves may include the ilioinguinal, genitofemoral, lateral femoral cutaneous, suprascapular, or femoral nerve.

[0053] FIG. IB is a conceptual diagram illustrating an example system that includes IMD 160 configured to deliver closed-loop stimulation to a spinal cord and open-loop stimulation to a peripheral nerve, such as a sacral nerve, in accordance with one or more techniques of this disclosure. System 152 of FIG. IB may be similar to system 100 of FIG. 1A, but system 152 may be configured to deliver closed-loop stimulation to spinal cord 166 and open-loop stimulation to a peripheral nerve, such as sacral nerve 172 or a pudendal nerve. In some examples, open-loop stimulation may be delivered bilaterally to the patient, such as to the sacral nerves on both sides of patient 105. Other example peripheral nerves may include the dorsal genital nerve, perineal nerve, inferior rectal nerve, pudendal nerve, external anal sphincter muscle, coccygeus muscle, levator ani muscle group, bulbocavemosus and / or bulbospongiosus muscle, gluteal muscles, e.g., gluteal maximus, gluteal medius, and gluteal minimus, perineal muscles, ischiocavemosus muscles, puborectalis muscles, piriformis muscles, detrusor muscle, or any other muscles, or any other nervous or muscle tissue that may be stimulated or from which physiological signals may be sensed of patient 105 through lead 164B (coupled to IMD 160 via connector 162). Leads 164A and 164B (collectively “leads 164”) may carry a plurality of electrodes 174A,174B at the distal end of each respective lead 164. IMD 160 may provide neurostimulation to treat symptoms of patient 105, such as fecal or urinary incontinence, pain, erectile dysfunction, and / or other sexual dysfunction. IMD 160 may thus be configured to provide sacral nerve stimulation in one example.Docket No.: A0013641W001

[0054] Leads 164 may include one or more additional leads that may carry electrodes 174. Electrodes 174 may be configured to deliver stimulation pulses and / or sense biopotentials that can be physiological signals of patient 105. In some examples, unipolar stimulation is possible where one electrode is a housing or otherwise on the housing (i.e., a can) of IMD 160.

[0055] Although the examples described in this disclosure are generally applicable to a variety of medical devices including external devices and IMDs, application of such techniques to IMDs and, more particularly, implantable electrical stimulators (e.g., neurostimulators) are described for purposes of illustration. More particularly, the disclosure will refer to a sacral nerve stimulation (SNS) for purposes of illustration, but without limitation as to other types of medical devices or other therapeutic applications of stimulation. Specifically, although FIG. IB is directed to SCS and sacral nerve stimulation (SNS), e.g., to treat pain, fecal or urinary incontinence, erectile dysfunction, or other sexual dysfunction, system 152 may be configured to treat any other condition that may benefit from electrical stimulation therapy. For example, system 152 may be configured to deliver SCS therapy, e.g., used to treat pain, and / or system 152 may be configured to deliver DBS therapy, e.g., used to treat obesity, gastroparesis, or psychiatric disorders (e.g., depression, mania, obsessive compulsive disorder, anxiety disorders, and the like). In this manner, system 152 may be configured to deliver one or more of sacral nerve stimulation (SNS), deep brain stimulation (DBS), spinal cord stimulation (SCS), tibial nerve stimulation (TNS), saphenous nerve stimulation, pelvic stimulation, pelvic floor stimulation, gastric stimulation, gastrointestinal stimulation, peripheral nerve field stimulation (PNFS), peripheral nerve field stimulation (PNFS), cortical stimulation (CS), or any other stimulation therapy capable of treating a condition of patient 105. Patient 195 ordinarily is a human patient. In some cases, however, therapy system 152 may be applied to other mammalian, non-mammalian, or non-human patients.

[0056] In some examples, sensed signals reflect changes in electrical current produced by the sum of electrical potential differences among nerves. Examples of neurological signals include, but are not limited to, bioelectric signals generated from local nerves and muscles sensed within one or more regions near nerve 120. In some examples, IMD 160 employs an electromyogram (EMG) to measure a muscle response or electrical activity in response to a nerve’s stimulation of the muscle. In some examples, IMD 160 measures evoked compound action potentials (ECAPs) which may be a measureDocket No.: A0013641W001of the quantity and magnitude of one or more action potentials evoked by stimulation. An electroneurogram (ENG) may record the electrical activity of neurons of the central nervous system (brain and spinal cord) or the peripheral nervous system (nerves and ganglions). An EMG may involve placing electrodes in or proximate neural tissue to record the electrical signals generated by muscle tissue. In some examples, IMD 106 may sense evoked signals, such as electroneurograms (ENGs), evoked compound action potentials (ECAPs), evoked resonant neural activity (ERNA), electromyogram (EMG), etc., or any combination, therefore. IMD 160 may additionally sense baseline signals which are different than evoked signals. In some examples, IMD 160 may sense evoked signals in response to one or more stimulations provided by IMD 160. IMD 160 may provide stimulations which are bipolar or unipolar. IMD 160 may provide stimulations which include active recharge or passive recharge. IMD 160 may provide stimulations wherein the polarity alternates between two or more electrodes of electrodes 174.

[0057] Lead 164B may be implanted to position electrodes 174B at suitable locations of nerve 172 through respective holes in sacrum 168. Leads 114 may be placed at any location along nerve 120 such that electrodes 116, 118 are capable of providing electrical stimulation to target tissue sites along nerve 120 during treatment. For example, electrodes 174B may be surgically implanted by inserting lead 164B through sacral foramina 170 of sacrum 168 of patient 112. Specifically, lead 164B may be inserted from a dorsal side of sacrum 168 through a sacral foramen to a ventral side of sacrum 168. Lead 164B may be inserted into the S3 sacral foramen such that electrodes extend along nerve 172 without manipulation of lead 164B on a ventral side of sacrum 168. Electrodes 174B may be electrically coupled to IMD 160 via one or more leads 164B. In some examples, lead 164B may be inserted into other foramen, such as SI, S2, S4 or S5.

[0058] FIG. 2 is a block diagram illustrating an example configuration of components of IMD 200, in accordance with one or more techniques of this disclosure. IMD 200 may be an example of IMD 1114 of FIG. 1A, or IMD 160 of FIG. IB. In the example shown in FIG. 2, IMD 200 includes stimulation generation circuitry 202, switch circuitry 204, sensing circuitry 206, communication circuitry 208, processing circuitry 210, storage device 212, sensor(s) 222, and power source 224.

[0059] In the example shown in FIG. 2, storage device 212 stores therapy stimulation programs 214 within storage device 212. Each stored therapy stimulation program of therapy stimulation programs 214 defines values for a set of electrical stimulationDocket No.: A0013641W001parameters (e.g., a stimulation parameter set for each pulse train or each slot of a series of slots), such as a stimulation electrode combination, electrode polarity, current or voltage amplitude, pulse width, pulse rate, and pulse shape. For example, therapy stimulation programs 214 may define closed-loop stimulation, open-loop stimulation, and parameters that define how these two types of stimulation can be delivered together, such as partially or fully interleaved, as described herein.

[0060] Accordingly, in some examples, stimulation generation circuitry 202 generates electrical stimulation signals in accordance with the electrical stimulation parameters noted above. Other ranges of stimulation parameter values may also be useful and may depend on the target stimulation site within patient 105. While stimulation pulses are described, stimulation signals may be of any form, such as continuous-time signals (e.g., sine waves) or the like. Switch circuitry 204 may 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 electrical circuitry configured to direct stimulation signals from stimulation generation circuitry 202 to one or more of electrodes 232, 234, or directed sensed signals from one or more of electrodes 232, 234 to sensing circuitry 206. In other examples, stimulation generation circuitry 202 and / or sensing circuitry 206 may include sensing circuitry to direct signals to and / or from one or more of electrodes 232, 234, which may or may not also include switch circuitry 204.

[0061] Sensing circuitry 206 monitors signals from any combination of electrodes 232, 234. In some examples, sensing circuitry 206 includes one or more amplifiers, filters, and analog -to-digital converters. Sensing circuitry 206 may be used to sense physiological signals, such as evoked compound action potentials (ECAPs). In some examples, sensing circuitry 206 detects ECAPs from a particular combination of electrodes 232, 234. In some cases, the particular combination of electrodes for sensing ECAPs includes different electrodes than a set of electrodes 232, 234 used to deliver stimulation pulses. Alternatively, in other cases, the particular combination of electrodes used for sensing ECAPs includes at least one of the same electrodes as a set of electrodes used to deliver stimulation pulses to patient 105. Sensing circuitry 206 may provide signals to an analog-to-digital converter, for conversion into a digital signal for processing, analysis, storage, or output by processing circuitry 210.

[0062] Communication circuitry 208 supports wireless communication between IMD 200 and an external programmer (not shown in FIG. 2) or another computing deviceDocket No.: A0013641W001under the control of processing circuitry 210. Processing circuitry 210 of IMD 200 may receive, as updates to programs, values for various stimulation parameters such as amplitude and electrode combination, from the external programmer via communication circuitry 208. Updates to the therapy stimulation programs 214 may be stored within storage device 212. Communication circuitry 208 in IMD 200, as well as telemetry circuits in other devices and systems described herein, such as the external programmer, may accomplish communication by radiofrequency (RF) communication techniques. In addition, communication circuitry 208 may communicate with an external medical device programmer (not shown in FIG. 2) via proximal inductive interaction of IMD 200 with the external programmer. The external programmer may be one example of external programmer 150 of FIG. 1A or IB. Accordingly, communication circuitry 208 may send information to the external programmer on a continuous basis, at periodic intervals, or upon request from IMD 200 or the external programmer.

[0063] Processing circuitry 210 may include any one or more of 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 the functions attributed to processing circuitry 210 herein may be embodied as firmware, hardware, software or any combination thereof. Processing circuitry 210 controls stimulation generation circuitry 202 to generate stimulation signals according to therapy stimulation programs 214 stored in storage device 212 to apply stimulation parameter values specified by one or more of programs, such as amplitude, pulse width, pulse rate, and pulse shape of each of the stimulation signals.

[0064] In the example shown in FIG. 2, the set of electrodes 232 includes electrodes 232A, 232B, 232C, and 232D, and the set of electrodes 234 includes electrodes 234A, 234B, 234C, and 234D. In other examples, a single lead may include all eight electrodes 232 and 234 along a single axial length of the lead. Processing circuitry 210 also controls stimulation generation circuitry 202 to generate and apply the stimulation signals to selected combinations of electrodes 232, 234. In some examples, stimulation generation circuitry 202 includes a switch circuit (instead of, or in addition to, switch circuitry 204) that may couple stimulation signals to selected conductors within leads 230, which, in turn, deliver the stimulation signals across selected electrodes 232, 234. Such a switch circuit may be a switch array, switch matrix, multiplexer, or any other type of switchingDocket No.: A0013641W001circuit configured to selectively couple stimulation energy to selected electrodes 232, 234 and to selectively sense bioelectrical neural signals of a spinal cord of the patient or signals near a peripheral nerve (not shown in FIG. 2) with selected electrodes 232, 234.

[0065] In other examples, however, stimulation generation circuitry 202 does not include a switch circuit and switch circuitry 204 does not interface between stimulation generation circuitry 202 and electrodes 232, 234. In these examples, stimulation generation circuitry 202 includes a plurality of pairs of voltage sources, current sources, voltage sinks, or current sinks connected to each of electrodes 232, 234 such that each pair of electrodes has a unique signal circuit. In other words, in these examples, each of electrodes 232, 234 is independently controlled via its own signal circuit (e.g., via a combination of a regulated voltage source and sink or regulated current source and sink), as opposed to switching signals between electrodes 232, 234.

[0066] Electrodes 232, 234 on respective leads 230 may be constructed of a variety of different designs. For example, one or both of leads 230 may include one or more electrodes at each longitudinal location along the length of the lead, such as one electrode at different perimeter locations around the perimeter of the lead at each of the locations A, B, C, and D. In one example, the electrodes may be electrically coupled to stimulation generation circuitry 202, e.g., via switch circuitry 204 and / or switching circuitry of the stimulation generation circuitry 202, via respective wires that are straight or coiled within the housing of the lead and run to a connector at the proximal end of the lead. In another example, each of the electrodes of the lead may be electrodes deposited on a thin film. The thin film may include an electrically conductive trace for each electrode that runs the length of the thin film to a proximal end connector. The thin film may then be wrapped (e.g., a helical wrap) around an internal member to form the lead 230. These and other constructions may be used to create a lead with a complex electrode geometry.

[0067] Although sensing circuitry 206 is incorporated into a common housing with stimulation generation circuitry 202 and processing circuitry 210 in FIG. 2, in other examples, sensing circuitry 206 may be in a separate housing from IMD 200 and may communicate with processing circuitry 210 via wired or wireless communication techniques.

[0068] Storage device 212 may be configured to store information within IMD 200 during operation. Storage device 212 may include a computer-readable storage medium or computer-readable storage device. Storage device 212 may include, for example,Docket No.: A0013641W001random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), ferroelectric random access memories (FRAM), magnetic discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable memories (EEPROM). In some examples, storage device 212 is used to store data indicative of instructions for execution by processing circuitry 210. As discussed above, storage device 212 is configured to store therapy stimulation programs 214.

[0069] Sensor(s) 222 may include one or more sensing elements that sense values of a respective patient parameter. As described, electrodes 232 and 234 may be the electrodes that sense the characteristic value of the ECAP. Sensor(s) 222 may include one or more accelerometers, optical sensors, chemical sensors, temperature sensors, pressure sensors, or any other types of sensors. Sensor(s) 222 may output patient parameter values that may be used as feedback to control delivery of therapy. IMD 200 may include additional sensors within the housing of IMD 200 and / or coupled via one of leads 130 or other leads. In addition, IMD 200 may receive sensor signals wirelessly from remote sensors via communication circuitry 208, for example. In some examples, one or more of these remote sensors may be external to patient (e.g., carried on the external surface of the skin, attached to clothing, or otherwise positioned external to patient 105).

[0070] Power source 224 is configured to deliver operating power to the components of IMD 200. Power source 224 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery is rechargeable to allow extended operation. In some examples, recharging is accomplished through proximal inductive interaction between an external charger and an inductive charging coil within IMD 200. In other examples, power source 224 may include one or more primary batteries that are not rechargeable. Power source 224 may include any one or more of a plurality of different battery types, such as nickel cadmium batteries and lithium ion batteries.

[0071] FIG. 3 is a block diagram illustrating an example configuration of components of external programmer 300, in accordance with one or more techniques of this disclosure. External programmer 300 may be an example of external programmer 150 of FIG. 1A or IB. Although external programmer 300 may generally be described as a handheld device, external programmer 300 may be a larger portable device or a more stationary device. In addition, in other examples, external programmer 300 may beDocket No.: A0013641W001included as part of an external charging device or include the functionality of an external charging device. As illustrated in FIG. 3, external programmer 300 may include processing circuitry 352, storage device 354, user interface 356, communication circuitry 358, and power source 360. Storage device 354 may store instructions that, when executed by processing circuitry 352, cause processing circuitry 352 and external programmer 300 to provide the functionality ascribed to external programmer 300 throughout this disclosure. Each of these components, circuitry, or modules, may include electrical circuitry that is configured to perform some, or all of the functionality described herein. For example, processing circuitry 352 may include processing circuitry configured to perform the processes discussed with respect to processing circuitry 352.

[0072] In general, external programmer 300 includes any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the techniques attributed to external programmer 300, and processing circuitry 352, user interface 356, and communication circuitry 358 of external programmer 300. In various examples, external programmer 300 may include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. External programmer 300 also, in various examples, may include a storage device 354, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, a hard disk, a CD-ROM, including executable instructions for causing the one or more processors to perform the actions attributed to them. Moreover, although processing circuitry 352 and communication circuitry 358 are described as separate modules, in some examples, processing circuitry 352 and communication circuitry 358 are functionally integrated. In some examples, processing circuitry 352 and communication circuitry 358 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0073] Storage device 354 (e.g., a storage device) may store instructions that, when executed by processing circuitry 352, cause processing circuitry 352 and external programmer 300 to provide the functionality ascribed to external programmer 300 throughout this disclosure. For example, storage device 354 may include instructions that cause processing circuitry 352 to obtain a parameter set from memory, select a spatial electrode movement pattern, or receive a user input and send a corresponding command to IMD 200, or instructions for any other functionality. In addition, storage device 354 may include a plurality of programs, where each program includes a parameter set thatDocket No.: A0013641W001defines stimulation pulses, such as control pulses and / or informed pulses. Storage device 354 may also store data received from a medical device (e.g., IMD 114 or IMD 160). For example, storage device 354 may store ECAP related data recorded at a sensing module of the medical device, and storage device 354 may also store data from one or more sensors of the medical device. This ECAP related data may include ECAP information transmitted from an implantable medical device, such as IMD 110.

[0074] User interface 356 may include a button or keypad, lights, a speaker for voice commands, a display, such as a liquid crystal (LCD), light-emitting diode (LED), or organic light-emitting diode (OLED). In some examples the display includes a touch screen. User interface 356 may 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. In addition, as described herein, processing circuitry 352 may control user interface 356 to present graphical representations of ECAP information transmitted by IMD 110. User interface 356 may also receive user input via user interface 356. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. The input may request starting or stopping electrical stimulation, the input may request a new spatial electrode movement pattern or a change to an existing spatial electrode movement pattern, of the input may request some other change to the delivery of electrical stimulation. In some examples, user interface 356 may be configured to present information and / or receive user input regarding one or more parameters that defines closed-loop stimulation, open-loop stimulation, or the interactions or parameters associated with delivery of stimulation. These parameters may include sensing window durations, pre-pulse windows, total charge of pulses, acceptable number of withheld pulses, or any other parameters.

[0075] Communication circuitry 358 may support wireless communication between the medical device and external programmer 300 under the control of processing circuitry 352. Communication circuitry 358 may also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. In some examples, communication circuitry 358 provides wireless communication via an RF or proximal inductive medium. In some examples, communication circuitry 358 includes an antenna, which may take on a variety of forms, such as an internal or external antenna.Docket No.: A0013641W001

[0076] Examples of local wireless communication techniques that may be employed to facilitate communication between external programmer 300 and IMD 200 include RF communication according to the 802.11 or Bluetooth ® specification sets or other standard or proprietary telemetry protocols. In this manner, other external devices may be capable of communicating with external programmer 300 without needing to establish a secure wireless connection. As described herein, communication circuitry 358 may be configured to transmit a spatial electrode movement pattern or other stimulation parameter values to IMD 200 for delivery of electrical stimulation therapy.

[0077] In some examples, selection of stimulation parameters or therapy stimulation programs are transmitted to the medical device for delivery to a patient (e.g., patient 105 of FIG. 1A, IB). In other examples, the therapy may include medication, activities, or other instructions that patient 105 must perform themselves or a caregiver perform for patient 105. In some examples, external programmer 300 provides visual, audible, and / or tactile notifications that indicate there are new instructions. External programmer 300 requires receiving user input acknowledging that the instructions have been completed in some examples.

[0078] Power source 360 is configured to deliver operating power to the components of external programmer 300. Power source 360 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery is rechargeable to allow extended operation. Recharging may be accomplished by electrically coupling power source 360 to a cradle or plug that is connected to an alternating current (AC) outlet. In addition, recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within external programmer 300. In other examples, traditional batteries (e.g., nickel cadmium or lithium ion batteries) may be used. In addition, external programmer 300 may be directly coupled to an alternating current outlet to operate.

[0079] The architecture of external programmer 300 illustrated in FIG. 3 is shown as an example. The techniques as set forth in this disclosure may be implemented in the example external programmer 300 of FIG. 3, as well as other types of systems not described specifically herein. Nothing in this disclosure should be construed so as to limit the techniques of this disclosure to the example architecture illustrated by FIG. 3.

[0080] FIG. 4 is a timing diagram 400 illustrating an example of delivering open-loop electrical stimulation pulses together with closed-loop electrical stimulation andDocket No.: A0013641W001associated sensing windows. FIG. 4 is described with reference to IMD 200 of FIG. 2. As illustrated, timing diagram 400 includes first channel 402 that delivers open-loop stimulation to a first target neural site (e.g., a DRG or peripheral nerve). First channel 402 delivers a plurality of pulses 404 that may be referred to as a pulse train having a predetermined pulse frequency and / or duty cycle according to a stimulation parameter set. Second channel 406 delivers a plurality of closed-loop stimulation pulses (which may be referred to as a pulse train) that includes pulses 409A-409N (collectively “stimulation pulses 409”) that each can be configured to elicit an ECAP such as ECAPs 408A-408N (collectively “ECAPs 408”).

[0081] First channel 402 is a time / voltage (and / or current) graph indicating the voltage (or current) of at least one electrode of electrodes 232, 234 in an electrode configuration targeting a first neural site to receive open-loop stimulation in the form of pulses 404. Pulses 404 are shown has being biphasic and including an active recharge phase, but a passive recharge phase may be provided for one, some, or all of pulses 404 in other examples. In this manner, pulses 404 may be balanced biphasic square pulses with an interphase interval. In other words, each of control pulses 404 are shown with a negative phase and a positive phase separated by an interphase interval. For example, a pulse 404 may have a negative voltage for the same amount of time and amplitude that it has a positive voltage. It is noted that the negative voltage phase may be before or after the positive voltage phase.

[0082] Second channel 406 is a time / voltage (and / or current) graph indicating the voltage (or current) of at least one electrode of electrodes 232, 234 with an electrode configuration configured to deliver closed-loop stimulation to a second neural target, such as a portion of a spinal cord. In one example, the electrodes of second channel 406 may be located on a different lead as the electrodes of first channel 402. ECAPs 408 may be sensed at different electrodes of the same lead that delivers pulses 409, but are shown on the same channel 406 for ease of illustration. Pulses 409 are shown as biphasic pulses having an active recharge phase that can clear charge prior to sensing the respective ECAP 408. However, pulses 409 may include a passive recharge phase or combination of active and passive recharge phase. Although second channel 406 shows that IMD 200 is configured to sense ECAPs 408 after each pulse 409, IMD 200 may be configured to only sense ECAPs after less than all of pulses 409 (e.g., at a predetermined sensing rate) if ECAP sensing is not needed at the same frequency of the pulse frequency of pulsesDocket No.: A0013641W001409. ECAPs 408 are electrical signals which may propagate along a nerve away from the origination of pulses 409. In one example, ECAPs 408 are sensed by different electrodes than the electrodes used to deliver control pulses 409. In some examples, ECAPs 408 may be sensed by any electrodes of any leads. As described, the physiological signal can be an ECAP, and wherein the sensing circuitry is configured to sense the ECAP elicited by a pulse of the closed-loop electrical stimulation and during the sensing window following the pulse.

[0083] IMD 200 may control stimulation circuitry to deliver closed-loop electrical stimulation pulses 409 to a spinal cord of a patient via a first set of electrodes based on a physiological signal that can include ECAPs 408. The physiological signal may be a feedback signal that can be used by IMD 200 to adjust one or more parameter values defining closed-loop stimulation. Each of pulses 409 are delivered during a pulse window 412A, 412B, and 412N (collectively “pulse windows 412”). IMD 200 may sense, via sensing circuitry, ECAPs 408 and processing circuitry can receive, from the sensing circuitry, information representative of ECAPs 408 (e.g., a physiological signal) sensed from a patient during a sensing window 414A, 414B, or 414N (collectively “sensing windows 414”).

[0084] IMD 200 may limit the delivery of pulses 404 to periods of time that do not overlap with sensing windows 414. In this manner, IMD 200 may control the stimulation circuitry to deliver, outside of the sensing windows 414, open-loop electrical stimulation pulses 404 to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes. In some examples, IMD 200 may also limit the delivery of pulses 404 to periods of time that do not overlap with pulse windows 412 and / or with pre-pulse windows that may occur prior to each of pulses 409. To prevent this overlap of any of pulses 404 with the activity of closed-loop stimulation and sensing on channel 406, IMD 200 may remove any pulses 404 from the pulse train that would interfere. As shown in FIG. 4, this may result in the removal of pulses 404A, 404B, and 404N that would otherwise overlap in time with activity on channel 406. In this manner, at least some electrical stimulation pulses 409 of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses 404 of the open-loop electrical stimulation. IMD 200 is described has monitoring pulse windows 412, sensing windows 414, pre-pulse windows, etc. that indicate when activity occurs on the closed-loop channel. Alternatively, IMD 200 may track an “open window” from theDocket No.: A0013641W001closed-loop stimulation that indicates time during which other stimulation, such as openloop stimulation pulses 404, can be delivered. In any manner, open-loop electrical stimulation comprises a train of pulses 404 at a pulse frequency and including the at least some electrical pulses of the open-loop electrical stimulation, where IMD 200 is configured to withhold any pulses 404 of the train of pulses at the pulse frequency that overlap in time with at least sensing windows 414.

[0085] Each of sensing windows 414 may have a duration from 0.5 milliseconds (ms) to 5 ms or 6 ms following the pulse. In some examples, the sensing window may have a duration of about 0.5 ms, 1.0 ms, 1.5 ms, 2.0 ms, 2.5 ms, 3.0 ms, 3.5 ms, 4.0 ms. 4.5 ms, 5.0 ms, 5.5, ms, or 6.0 ms following an eliciting pulse of the closed-loop stimulation pulse 409. The pre-pulse window may have a duration of up to 1.0 ms immediately prior to the respective pulse 409. IMD 200 may be configured to withhold any pulses 404 of the train of pulses of channel 402 at the pulse frequency of the open-loop stimulation that occur within 1 ms of any pulse 409 and / or sensing window 414.

[0086] Pulses 409 of the closed-loop neuromodulation may be biphasic and may include active or passive recharge recovery phases. In some examples, the pulse frequency of the closed-loop neuromodulation is from 2 Hz to 250 Hz. In one examples, the pulse frequency is about 50 Hz. The pulse width of the closed-loop neuromodulation may be from 60 ps to 500 ps. In some examples, the pulse width may be about 200 ps. The pulse amplitude of the closed-loop neuromodulation may be from 0.5 mA to 25.5 mA. In one example, the pulse amplitude may be about 4 mA, but the pulse amplitude (or other parameter) may be adjusted by the user and / or automatically according to the closed-loop instructions. In some examples, the nominal charge / phase of the closed-loop neuromodulation is about 800 nanocoulombs (nC) (4 mA * 200 ps), but that charge / phase may be adjusted or customized for individual patients.

[0087] Pulses 404 of the open-loop stimulation may have a pulse frequency from 100 Hz to 1200 Hz. However, that effective pulse frequency may end up being variable if IMD 200 removes or withholds any of pulses 404 to prevent overlapping with sensing window 414 or any other activity of closed-loop stimulation. Pulses 404 may generally have less charge than pulses 409. In some examples, pulses 404 may be “sub-threshold” in that pulses 404 have an intensity that is less than an intensity required to be perceptible by the patient, trigger motor activity, or otherwise case detectable neural activity.Docket No.: A0013641W001

[0088] FIGS. 5 A and 5B are timing diagrams illustrating an example of delivering open-loop electrical stimulation pulses together with closed-loop electrical stimulation and associated sensing windows. As shown in FIGS. 5A and 5B, timing diagrams 500 and 510 provide examples of different methods for delivering open-loop and closed-loop stimulation. Timing diagram 500 shows that pulses 502 can be delivered to two different target tissues, such as open-loop pulses to the DRG and closed-loop pulses to the spinal cord. Pulses 502 in the lower train can be closed-loop stimulation, less frequent, configured to elicit a detectable physiological signal, and delivered to a different target tissue, such as the spinal cord. Series of slots 504 (e.g., slot 504Aand slots 504B) indicates that there are four slots that represent a period of time during which a single stimulation pulse can be delivered. Put another way, 4 programs (or respective pulse trains) can be active at the same time, which one pulse from each program being deliverable in its respective slot. The series of slots 504 then continues to repeat over time. In this manner, the pulses of the four programs (or respective pulse trains) are at least partially interleaved over time.

[0089] In the upper train example for open-loop stimulation, the pulses delivered during the second, third, and fourth slots 504B of each series of slots 504. The group rate determines the frequency that the series of slots 504 is repeated. Therefore, if the group rate is 300 Hz, the pulses of the upper train have a maximum interpulse frequency of 1200 Hz and an average of 900 Hz is achieved because the first slot of every series of slots 504 is occupied by the lower train program (the closed-loop stimulation) delivered to a different target tissue via a different electrode combination. As shown in the lower train of timing diagram 500, the pulse in slot 504A is only delivered once every sixth occurrence of series of slots 504. When the pulse is not delivered in a series of slots 504, that slot remains empty such that no pulse is delivered. Therefore, the lower train achieves a frequency of 50 Hz. Pattern 506 indicates one complete repeating pattern for the upper and lower trains together. As IMD 200 continues to deliver pulses according to the programs and repeating series of slots 504, stimulation is delivered repeatedly with pattern 506 as long as stimulation is being delivered. However, sensing window 508 may follow each pulse of closed-loop stimulation. Therefore, IMD 200 may remove the first two pulses of pulses 504B to prevent overlapping of the open-loop pulses from the sensing window 508.Docket No.: A0013641W001

[0090] However, timing diagram 500 indicates stimulation delivery that consumes more power than may be necessary to treat the patient. Instead, the open-loop stimulation may be effective at lower average pulse frequencies. This lower average frequency is still greater than the frequency of the closed-loop pulse train, but it may enable IMD 200 to conserve power proportional the fewer number of pulses generated by IMD 200 than in timing diagram 300. In the example of timing diagram 510, the open-loop stimulation may include one or more trains of electrical stimulation pulses 512 in the open-loop train. The closed-loop pulses may include a train of electrical stimulation pulses 512 in the lower train. Since series of slots 514 (e.g., slots 514A and 514B) only includes three slots, three pulses are shown in respective slots in time. The series of slots 514 has a group rate of 100 Hz, and the second stimulation only includes a pulse in the first slot 514A of every other series of pulses 514 such that the second stimulation has a frequency of 50 Hz. The first stimulation of the open-loop train includes two trains of pulses (but could include three or more distinct trains), where one train includes a pulse in the second slot of slots 514B of every series of pulses 514 and another train includes a pulse in the third slot of slots 514B of every series of pulses 514. In this manner, each train in the open-loop train has a respective frequency of 100 Hz, which results in an interpulse frequency of 300 Hz for the open-loop train and an average frequency of 200 Hz. Pattern 516 indicates one complete repeating pattern for the open-loop and closed-loop trains together. As IMD 200 continues to deliver pulses according to the programs and repeating series of slots 514, stimulation is delivered repeatedly with pattern 516 as long as stimulation is being delivered. Generally, each frequency of the respective pulse trains in the open-loop train are greater than the frequency of the closed-loop pulse train, but they may be the same frequency or switched frequencies. Since no pulse of the open-loop pulses overlap with the sensing window 518, IMD 200 does not need to remove any open-loop pulses.

[0091] Although the concept of a series of slots is provided as one example mechanism for managing the delivery of pulses for the open-loop and closed-loop stimulation pulses, other management techniques may be used in other examples. For example, IMD 200 may have a flexible programming architecture that enables processing circuitry 210 to schedule different pulses for different electrode combinations at any frequency desired. For example, IMD 200 may simply run multiple different programsDocket No.: A0013641W001that define respective pulse trains interleaved as needed to achieve the respective frequencies of each pulse train.

[0092] FIG. 6 is a flow diagram illustrating an example technique for delivering open-loop electrical stimulation pulses outside of sensing windows associated with closed-loop electrical stimulation pulses. For convenience, FIG. 6 is described with respect to IMD 200 of FIG. 2. However, the techniques of FIG. 6 may be performed by different components of IMD 200 or by additional or alternative medical devices, such as IMDs 114, 160, or programmers 150 or 300.

[0093] In the example of FIG. 6, processing circuitry 210 controls stimulation circuitry to deliver open-loop stimulation pulses (600). If any upcoming closed-loop pulse or sensing window will interfere with the delivery of one or more of the open-loop stimulation pulses (“YES” branch of block 602), processing circuitry 210 can withhold any of the open-loop stimulation pulses that would overlap in time with the closed-loop stimulation pulse, pre-pulse window, or sensing window that follows the closed-loop stimulation pulse configured to enable sensing of a biopotential such as an ECAP signal (604). In some examples, IMD 200 may may other adjustments to open-loop pulses that may not be fully withholding a pulse. For example, IMD 200 may adjusts the recharge phase from a passive recharge phase to an active recharge phase if such an adjustment will terminate the open-loop pulse prior to the conflicting stimulation or sensing of the closed-loop stimulation.

[0094] If any upcoming closed-loop pulse or sensing window will not interfere with the delivery of one or more of the open-loop stimulation pulses (“NO” branch of block 602), processing circuitry 210 can continue to control stimulation circuitry to deliver the closed-loop stimulation pulse(s) (606). Processing circuitry 210 can also control sensing circuitry to sense a physiological signals, such as a biopotential that can include an ECAP signal (608). Processing circuitry 210 can then continue to deliver additional open-loop stimulation pulses according to the predefined pulse frequency and / or schedule (600).

[0095] The open-loop and closed-loop stimulation pulses are different in that processing circuitry 210 can only adjust a parameter of the closed-loop stimulation based on a feedback signal, such as a physiological signal, without adjusting any parameters defining the open-loop stimulation. The open-loop stimulation may be adjusted in response to user input, but that is not an automatic change and thus processing circuitry 210 continues to deliver open-loop stimulation according to original parameter valuesDocket No.: A0013641W001unless manually changed by user input or otherwise stopped. As such, processing circuitry 210 may be configured to adjust, based on the physiological signal, at least one stimulation parameter defining the closed-loop electrical stimulation and also be configured to maintain stimulation parameters defining the open-loop electrical stimulation without adjustment based on any physiological signal.

[0096] FIG. 7 is a conceptual diagram of an example user interface 700 that enables a user to enable or disable closed-loop stimulation for a stimulation program. As shown in FIG. 7, screen 702 is an example screen of user interface 700 and may be presented by a display device of external device 150 or external programmer 300. Screen 702 may present electrode field 704 that displays available electrodes implanted in the patient and the electrodes that have been selected as cathodes and / or anodes for stimulation of the selected program (Program 2) in this example. Screen 702 also displays stimulation parameters for the program, which can include amplitude 710, pulse width 712, pulse rate 714, and electrode redistribution 716. Each of these parameters may be selectable and / or adjustable via user interaction with the respective element of screen 702. Sensing indicator 708 indicates whether or not the system is actively sensing physiological signals, such as an ECAP signal.

[0097] Closed-loop toggle button 706 enables the user to turn closed-loop stimulation on (active) or off (inactive). When active, IMD 200 may enable sensing of physiological signals and / or enable the automatic adjustment of closed-loop stimulation pulses based on the sensed physiological signals. When inactive, IMD 200 may disable the automatic adjustment of pulse, and the sensing of physiological signals may, or may not, also be disabled. In some examples, physiological signals, such as ECAPs, may continue to be sensed if needed for patient monitoring. The user may turn off closed-loop stimulation for a particular program if not needed for the patient or if the open-loop stimulation will lose pulses and no longer be effective for that therapeutic purpose. In some examples, when closed-loop stimulation is active, user interface 700 may display the number or percent of pulses of open-loop stimulation on another program that will be removed due to interference with the closed-loop stimulation activity. In some examples, user interface 700 may only display a warning when the number of percent of pulses of the open-loop stimulation that will be removed exceeds a predetermined threshold. Alternatively, user interface 700 may lock-out closed-loop stimulation from being used if the programmed open-loop stimulation will be reduced exceeding the threshold pulse removal.Docket No.: A0013641W001

[0098] FIG. 8 is a conceptual diagram of an example user interface 700 that displays groups of respective stimulation programs and an indication of which programs are closed-loop stimulation enabled or disabled. In the example of FIG. 8, user interface 700 includes a different screen 802 that provides the programs that may be selected for use with the patient and which groups are active. Group 804 is shown as active and includes program 806 and 808. The programs can also indicate if closed-loop control has been enabled or disabled for each program. Program 806 indicates that closed-loop control has been enabled, but program 808 indicates that closed-loop control has been disabled. The user may select a desired program to change the closed-loop control status, which may switch to screen 702 to make that change.

[0099] The following examples are described herein.

[0100] Example 1. A system comprising: processing circuitry configured to: receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window; control, based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; and control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the openloop electrical stimulation.

[0101] Example 2. The system of example 1, wherein the processing circuitry is configured to control the stimulation circuitry to deliver, outside of the sensing window, the open-loop electrical stimulation to the dorsal root ganglion via the second set of electrodes.

[0102] Example 3. The system of any of examples 1 or 2, wherein the processing circuitry is configured to control the sensing circuitry to generate the information representative of the physiological condition sensed during the sensing window.

[0103] Example 4. The system of any of examples 1 through 3, wherein the physiological signal is an evoked compound action potential (ECAP), and wherein the sensing circuitry is configured to sense the ECAP elicited by a pulse of the closed-loop electrical stimulation and during the sensing window following the pulse.Docket No.: A0013641W001

[0104] Example 5. The system of example 4, wherein the sensing window has a duration from 0.5 milliseconds (ms) to 5 ms following the pulse.

[0105] Example 6. The system of any of examples 1 through 5, wherein the openloop electrical stimulation comprises a train of pulses at a pulse frequency including the at least some electrical pulses of the open-loop electrical stimulation, and wherein the processing circuitry is configured to withhold any pulses of the train of pulses that overlap in time with the sensing window.

[0106] Example 7. The system of example 6, wherein the processing circuitry is configured to withhold any pulses of the train of pulses that occur within 1 ms of any pulse of the closed-loop electrical stimulation.

[0107] Example s. The system of any of examples 6 or 7, wherein the pulse frequency is from 100 Hz to 1200 Hz

[0108] Example 9. The system of any of examples 1 through 8, wherein the closed-loop electrical stimulation comprises a pulse frequency from 2 Hz to 250 Hz, a pulse width from 60 microseconds to 500 microseconds, and an amplitude from 0.5 milliamps (mA) to 25.5 mA.

[0109] Example 10. The system of any of examples 1 through 9, further comprising an implantable medical device comprising a housing that encloses the stimulation circuitry, the sensing circuitry, and the processing circuitry.

[0110] Example 11. The system of any of examples 1 through 9, further comprising: a first implantable medical device comprising a first housing that encloses a first portion of the stimulation circuitry configured to deliver the closed-loop electrical stimulation; and a second implantable medical device different from the first implantable medical device, wherein the second implantable medical device comprises a second housing that encloses a second portion of the stimulation circuitry configured to deliver the open-loop electrical stimulation.

[0111] Example 12. The system of any of examples 1 through 11, wherein processing circuitry is configured to adjust, based on the physiological signal, at least one stimulation parameter defining the closed-loop electrical stimulation, and wherein the processing circuitry is configured to maintain stimulation parameters defining the openloop electrical stimulation without adjustment based on any physiological signal.

[0112] Example 13. A method comprising: receiving, by processing circuitry and from sensing circuitry, information representative of a physiological signal sensed from aDocket No.: A0013641W001patient during a sensing window; controlling, by the processing circuitry and based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; controlling, by the processing circuitry, the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open-loop electrical stimulation.

[0113] Example 14. The method of example 13, further comprising controlling the stimulation circuitry to deliver, outside of the sensing window, the open-loop electrical stimulation to the dorsal root ganglion via the second set of electrodes.

[0114] Example 15. The method of any of examples 13 or 14, further comprising controlling the sensing circuitry to generate the information representative of the physiological condition sensed during the sensing window.

[0115] Example 16. The method of any of examples 13 through 14, wherein the physiological signal is an evoked compound action potential (ECAP), and wherein the method further comprises sensing, by the sensing circuitry, the ECAP elicited by a pulse of the closed-loop electrical stimulation and during the sensing window following the pulse.

[0116] Example 17. The method of any of examples 13 through 16, wherein openloop electrical stimulation comprises a train of pulses at a pulse frequency and comprising the at least some electrical pulses of the open-loop electrical stimulation, and wherein the method further comprises withholding any pulses of the train of pulses at the pulse frequency that overlap in time with the sensing window.

[0117] Example 18. The method of example 17, wherein the processing circuitry is configured to withhold any pulses of the train of pulses at the pulse frequency that occur within 1 ms of any pulse of the closed-loop electrical stimulation.

[0118] Example 19. The method of any of examples 13 through 18, wherein the closed-loop electrical stimulation comprises a pulse frequency from 2 Hz to 250 Hz, a pulse width from 60 microseconds to 500 microseconds, and an amplitude from 0.5 milliamps (mA) to 25.5 mA.Docket No.: A0013641W001

[0119] Example 20. The method of any of examples 13 through 19, wherein an implantable medical device comprises a housing that encloses the stimulation circuitry, the sensing circuitry, and the processing circuitry.

[0120] Example 21. A computer-readable storage medium comprising instructions that, when executed, cause the processing circuitry to: receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window; control, based on the feedback signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; and control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open-loop electrical stimulation.

[0121] The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic QRS circuitry, as well as any combinations of such components, embodied in external devices, such as physician or patient programmers, stimulators, or other devices. The terms “processor” and “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry, and alone or in combination with other digital or analog circuitry.

[0122] For aspects implemented in software, at least some of the functionality ascribed to the systems and devices described in this disclosure may be embodied as instructions on a computer-readable storage medium such as random access memory (RAM), ferroelectric random access memory (FRAM), DRAM, SRAM, FRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. The instructions may be executed to support one or more aspects of the functionality described in this disclosure.

[0123] In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware orDocket No.: A0013641W001software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components. Also, the techniques could be fully implemented in one or more circuits or logic elements. The techniques of this disclosure may 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 a set of ICs, and / or discrete electrical circuitry, residing in an IMD and / or external programmer.

Claims

Docket No.: A0013641W001WHAT IS CLAIMED IS:

1. A system comprising:processing circuitry configured to:receive, from sensing circuitry, information representative of a physiological signal sensed from a patient during a sensing window;control, based on the physiological signal, stimulation circuitry to deliver closed-loop electrical stimulation to a spinal cord of a patient via a first set of electrodes; and control the stimulation circuitry to deliver, outside of the sensing window, open-loop electrical stimulation to at least one of a dorsal root ganglion or peripheral nerve via a second set of electrodes different from the first set of electrodes, wherein at least some electrical stimulation pulses of the closed-loop electrical stimulation are interleaved with at least some electrical stimulation pulses of the open-loop electrical stimulation.

2. The system of claim 1, wherein the processing circuitry is configured to control the stimulation circuitry to deliver, outside of the sensing window, the open-loop electrical stimulation to the dorsal root ganglion via the second set of electrodes.

3. The system of any of claims 1 or 2, wherein the processing circuitry is configured to control the sensing circuitry to generate the information representative of the physiological condition sensed during the sensing window.

4. The system of any of claims 1 through 3, wherein the physiological signal is an evoked compound action potential (ECAP), and wherein the sensing circuitry is configured to sense the ECAP elicited by a pulse of the closed-loop electrical stimulation and during the sensing window following the pulse.

5. The system of claim 4, wherein the sensing window has a duration from 0.5 milliseconds (ms) to 5 ms following the pulse.

6. The system of any of claims 1 through 5, wherein the open-loop electrical stimulation comprises a train of pulses at a pulse frequency including the at least some electrical pulses of the open-loop electrical stimulation, and wherein the processingDocket No.: A0013641W001circuitry is configured to withhold any pulses of the train of pulses that overlap in time with the sensing window.

7. The system of claim 6, wherein the processing circuitry is configured to withhold any pulses of the train of pulses that occur within 1 ms of any pulse of the closed-loop electrical stimulation.

8. The system of any of claims 6 or 7, wherein the pulse frequency is from 100 Hz to 1200 Hz.

9. The system of any of claims 1 through 8, wherein the closed-loop electrical stimulation comprises a pulse frequency from 2 Hz to 250 Hz, a pulse width from 60 microseconds to 500 microseconds, and an amplitude from 0.5 milliamps (mA) to 25.5 mA.

10. The system of any of claims 1 through 9, further comprising an implantable medical device comprising a housing that encloses the stimulation circuitry, the sensing circuitry, and the processing circuitry.

11. The system of any of claims 1 through 9, further comprising:a first implantable medical device comprising a first housing that encloses a first portion of the stimulation circuitry configured to deliver the closed-loop electrical stimulation; anda second implantable medical device different from the first implantable medical device, wherein the second implantable medical device comprises a second housing that encloses a second portion of the stimulation circuitry configured to deliver the open-loop electrical stimulation.

12. The system of any of claims 1 through 11, wherein the processing circuitry is configured to adjust, based on the physiological signal, at least one stimulation parameter defining the closed-loop electrical stimulation, and wherein the processing circuitry is configured to maintain stimulation parameters defining the open-loop electrical stimulation without adjustment based on any physiological signalDocket No.: A0013641W00113. The system of any of claims 1 through 12, wherein the processing circuitry is configured to control the stimulation circuitry to deliver, outside of the sensing window, the open-loop electrical stimulation to the dorsal root ganglion.

14. The system of any of claims 1 through 12, wherein the processing circuitry is configured to control the stimulation circuitry to deliver, outside of the sensing window, the open-loop electrical stimulation to the peripheral nerve.

15. A computer-readable storage medium comprising instructions that, when executed, causes the processing circuitry to perform the functions of any of claims 1 through 14.

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