Electrode-tissue interface stability determination

Abstract

Systems, devices, and techniques are configured to determine patient stability for sensing or closed-loop control of stimulation. In one example, a system includes processing circuitry configured to receive information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes and determine, based on the electrical signals, a metric. The processing circuitry can also be configured to compare the metric to a threshold, determine that the metric exceeds the threshold, and responsive to determining that the metric exceeds the threshold, enable closed-loop control of electrical stimulation therapy.

Description

Docket No.: A0012656W001 / 1123-837WO01ELECTRODE-TISSUE INTERFACE STABILITY DETERMINATION

[0001] This application is a PCT application that claims priority to, and the benefit of, U.S. Provisional Patent Application No. 63 / 700,386, filed September 27, 2024, the entire contents of which is incorporated herein by reference.TECHNICAL FIELD

[0002] This disclosure generally relates to electrical stimulation, and more specifically, to sensing changes over time.BACKGROUND

[0003] Medical devices may be external or implanted, and may sense electrical signals (e.g., neural signals from central and / or peripheral nerves) and / or deliver electrical stimulation therapy to various tissue sites of a patient to treat a variety of symptoms or conditions such as, for example, one or more of chronic pain, tremor, Parkinson’s disease, other movement disorders, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, gastroparesis, sleep apnea, neural control of prosthetic devices, or stimulation to provide peripheral sensation. A medical device delivers 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. For bipolar stimulation, the electrodes used for stimulation may be on one or more leads. For unipolar stimulation, the electrodes may include one or more leads and an electrode on a stimulator housing located remotely from the target site (e.g., near clavicle or near buttocks). It may be possible to use leadless stimulation using electrodes mounted on the stimulator housing. Hence, electrical stimulation is used in different therapeutic applications, such as deep brain stimulation (DBS), spinal cord stimulation (SCS), pelvic floor stimulation, gastric stimulation, or peripheral nerve field stimulation (PNFS).

[0004] A clinician (or other healthcare provider) or patient may select values for a number of programmable parameters, via an external programmer, in order to define the electrical stimulation therapy to be delivered by the implantable stimulator to a patient. For example, the clinician may select one or more electrodes for delivery of the stimulation, a polarity of each selected electrode, a voltage or current pulse amplitude, a pulse width, and a pulse rate as stimulation parameters. A set of parameters, such as a set including electrodeDocket No.: A0012656W001 / 1123-837WO01 combination, electrode polarity, amplitude, pulse width, and pulse rate, may be referred to as a program in the sense that they define the electrical stimulation therapy to be delivered to the patient.SUMMARY

[0005] This disclosure describes example techniques for managing an electrode-tissue interface post-implantation. An implantable medical device (IMD) and / or an external programmer for the IMD may monitor one or more sensed electrical signals after implantation of the IMD. The system may generate a metric from the sensed electrical signals and determine a convergence metric representative of how the electrode-tissue interface may change post-implantation. One or more convergence metrics that exceeds a threshold may indicate that an electrode-tissue interface has stabilized. Therefore, in response to a convergence metric exceeding a threshold, the system may perform one or more functions that may benefit therapy. For example, the system may enable closed-loop stimulation therapy, which may include initiating sensing for automatic adjustment of a stimulation parameter that defines therapy and / or notifying a clinician that closed-loop stimulation therapy can begin. In some examples, the system may perform a function such as adjusting one or more stimulation parameters or notifying the clinician that the threshold has been exceeded.

[0006] In one example, a system includes processing circuitry configured to: receive information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determine, based on the electrical signals, a metric; compare the metric to a threshold; determine that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enable closed-loop control of electrical stimulation therapy.

[0007] In another example, a method includes receiving, by processing circuitry, information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determining, based on the electrical signals, a metric; comparing the metric to a threshold; determining that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enabling closed-loop control of electrical stimulation therapy.

[0008] In another example, a non-transitory computer-readable storage medium comprising instructions that, when executed by processing circuitry, cause the processing circuitry to: receive information representative of electrical signals sensed via one or moreDocket No.: A0012656W001 / 1123-837WO01 implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determine, based on the electrical signals, a metric; compare the metric to a threshold; determine that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enable closed-loop control of electrical stimulation therapy.

[0009] The details of one or more examples of the techniques of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 A is a conceptual diagram illustrating an example system that includes an implantable medical device (IMD) configured to deliver electrical stimulation to a brain of patient according to an example of the techniques of the disclosure.

[0011] FIG. IB is a conceptual diagram illustrating another example system that includes an implantable medical device (IMD) configured to deliver electrical stimulation to a spinal cord of a patient according to an example of the techniques of the disclosure.

[0012] FIG. 1C is a conceptual diagram illustrating another example system that includes an implantable medical device (IMD) configured to deliver electrical stimulation to one or more pelvic nerves of a patient according to an example of the techniques of the disclosure.

[0013] FIG. 2 is a block diagram of the example IMD of FIG. 1 for delivering electrical stimulation according to an example of the techniques of the disclosure.

[0014] FIG. 3 is a block diagram of the external device of FIG. 1 for communicating with a medical device according to an example of the techniques of the disclosure.

[0015] FIG. 4 is a flowchart illustrating an example operation of a device configured to determine one or more convergence metrics and provide an alert based on the one or more convergence metrics.

[0016] FIG. 5 is a flowchart illustrating an example operation of a device configured to determine one or more convergence metrics based on local field potentials and provide an alert based on the one or more convergence metrics.

[0017] FIGS. 6A, 6B, and 6C are example user interfaces for a spinal cord stimulator that indicate a convergence status of leads of the spinal cord stimulator.

[0018] FIGS. 7A, 7B, and 7C are example user interfaces for a deep brain stimulator that indicate a convergence status of leads of the deep brain stimulator.Docket No.: A0012656W001 / 1123-837WO01

[0019] FIG. 8 A is an example of local field potential data for a post-surgical microlesion effect that trend upwards.

[0020] FIG. 8B is an example of local field potential data for a post-surgical microlesion effect that trend upwards to a convergence level.

[0021] FIG. 8C is an example of local field potential data for a post-surgical microlesion effect that does not trend upwards towards a convergence level.DETAILED DESCRIPTION

[0022] This disclosure describes example devices, systems, and techniques related to managing an electrode-tissue interface post-implantation. Currently, healthcare providers (e.g., a clinician or other professional) may wait two or more weeks after implantation of spinal cord stimulation electrodes to activate the electrodes. These two or more weeks allows the electrode-tissue interface to normalize. Some clinicians want to activate spinal cord stimulation on the day of implantation, but the electrode-tissue interface may not be stable yet. Similarly, clinicians may activate deep brain stimulation electrodes immediately after implantation to provide immediate relief to the patient, but the unstable electrode-tissue interface means that the same stimulation level may result in changing brain responses as the electrode-tissue interface heals. Therefore, a method of determining when the electrodetissue interface is stable and thereafter sending a notification to the clinician and / or changing stimulation parameters can be beneficial to clinician workflow and patient therapy.

[0023] The electrode-tissue interface is the tissue of a patient that has an electrode implanted nearby. The electrode may deliver stimulation that may change neural responses of the nearby tissue. Implantation of the electrode may result in localized micro-lesioning (i.e., a surgical stun) of the tissue immediately after implantation. Micro-lesioning may result in an instability to the electrode-tissue interface as the tissue heals in the following days or weeks. The instability of the electrode-tissue interface may lead to different therapeutic results and neural responses for the same therapy input. As the tissue heals, neural responses (e.g., local field potentials (LFPs)) can stabilize to a point where signals can be more reliably measured and / or stimulation delivery is appropriate with tissue-electrode conditions.

[0024] As described herein, a system can track sensed electrical signals (or other sensed data) over time and statistics may be calculated for the neural response. The system can use such statistics to determine convergence metrics. If one or more convergence metrics meets a threshold, then the system may determine that an electrode-tissue interface has stabilized and use of the IMD can proceed. Once the electrode-tissue interface has sufficiently stabilizedDocket No.: A0012656W001 / 1123-837WO01 based on a standard set or adopted by the clinician, the system can perform any number of actions, such as enabling stimulation, enabling closed-loop stimulation therapy, adjusting one or more stimulation parameters, or sending a notification to the clinician that the threshold was exceeded by the monitored metric. A notification can enable the clinician to begin therapy more quickly once the interface has stabilized, enables prompt and informed adjustments to the therapy based on changes in the electrode-tissue interface, and can personalizes the therapy delivery and treatment to an individual patient based on their individual biology.

[0025] An implantable medical device may have stimulation circuitry that may be connected through a lead to an electrode. The electrode may be positioned at an implant location such as an electrode-tissue interface. The stimulation circuitry may be configured to deliver a pulse of electrical stimulation from the electrode to tissue near the electrode-tissue interface thereby resulting in a response of the nearby tissue. The response, or any other electrical field potentials which may or may not be a response to a pulse of electrical stimulation, such as local field potentials (LFPs) may be recorded by the same or different electrodes at the electrode-tissue interface via sensing circuitry. Alternatively or additionally, the electrodes may also detect far-field cardiac activity of the heart beating, which could be used as a marker of noise over time that may be indicative of convergence, or tissue interface stability. The sensing circuitry may record continuously at a recording frequency or may record in response to specific events. The implantable medical device may include processing circuitry. The processing circuitry may be housed within a housing (e.g., a can) of the implantable medical device, wherein the can is hermetically sealed to keep fluids out of the electronics of the implantable medical device. The processing circuitry may calculate one or more metrics based on the signals recorded by the sensing circuitry. The one or more metrics may thereafter be compared to one or more thresholds by the processing circuitry. The processing circuitry may determine a convergence status based on the comparison of the one or more metrics to the one or more thresholds. The processing circuitry may automatically adjust the stimulation parameters of the stimulation circuitry based on the convergence metrics and / or the convergence status. Additionally, or alternatively, processing circuitry may send a notification to the clinician based on the convergence metrics and / or the convergence status.

[0026] The metric may be any trends, values, transformations, or suitable features of electrical signals recorded by the sensing circuitry. The threshold may be based on whether the electrode-tissue interface is sufficiently stable (e.g., whether the electrode-tissue interfaceDocket No.: A0012656W001 / 1123-837WO01 has healed enough from the micro lesioning resulting from implantation) to receive stimulation. Stability may be determined based on decreasing variation (e.g., a variance, a standard deviation, etc.) in signals, increasing or decreasing amplitude of signals, or any combination of such characteristics of the sensed electrical signals. This threshold may be based on population averages or may be individualized based on the specific attributes of the patient. Providing the alert may include the implantable medical device sending a notification through communication circuitry in the implantable medical device to a second device. Alternatively, the clinician may setup the implantable medical device to automatically begin treatment in response to the threshold being met. Automatically beginning treatment in response to the threshold being met enables the implantable medical device to deliver treatment at the earliest possible time that the electrode-tissue interface is stable.

[0027] FIG. 1 A is a conceptual diagram illustrating an example system 100A that includes an implantable medical device (IMD) 106 configured to deliver deep brain stimulation (DBS) to a brain 120 of a patient 112. Although the examples described in this disclosure are generally applicable to a variety of electronic communication devices including external devices and IMDs (such as system 100B of FIG. IB or system 100C of FIG. 1C), 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 of FIG. 1 A will refer to an implantable medical device which may include an implantable pulse generator configured to deliver deep brain stimulation for purposes of illustration. System 100 A may be configured to deliver one or more of deep brain stimulation (DBS) such as in FIG. 1 A, spinal cord stimulation (SCS) such as in FIG. IB, sacral nerve stimulation (SNS) such as in FIG. 1C, tibial nerve stimulation (TNS), electrical stimulation and targeted drug delivery (TDD), pelvic stimulation, gastric stimulation, or peripheral nerve field stimulation (PNFS), or any other stimulation therapy capable of treating a condition of patient 122.

[0028] DBS, or other therapies such as SNS or TNS, may operate open loop or, alternatively, adaptive format in the sense that IMD 106 may adjust, increase, or decrease the magnitude of one or more parameters of the DBS in response to changes in patient activity or movement, a severity of one or more symptoms of a disease of the patient, a presence of one or more side effects due to the DBS, or one or more sensed signals of the patient. One example of system 100 is a bi-directional DBS system with capabilities to both deliver stimulation and sense intrinsic electrical signals (e.g., neuronal signals such as LFPs orDocket No.: A0012656W001 / 1123-837WO01ECAPs). System 100A may enable “closed-loop” therapy where IMD 106 may continuously monitor the state of certain biomarker signals and deliver stimulation according to preprogrammed routines based on the biomarker signals.

[0029] System 100 A may be configured to treat a patient condition, such as a movement disorder, neurodegenerative impairment, a mood disorder, or a seizure disorder of patient 112. Patient 112 ordinarily is a human patient. In some cases, however, therapy system 100 A may be applied to other mammalian or non-mammalian, non-human patients. While movement disorders and neurodegenerative impairment are primarily referred to herein, in other examples, therapy system 100 A may provide therapy to manage symptoms of other patient conditions, such as, but not limited to, seizure disorders (e.g., epilepsy) or mood (or psychological) disorders (e.g., major depressive disorder (MDD), bipolar disorder, anxiety disorders, post-traumatic stress disorder, dysthymic disorder, and obsessive-compulsive disorder (OCD)) as well as, for example, neural control of prosthetic devices or stimulation to provide sensory feedback to the patients. At least some of these disorders may be manifested in one or more patient movement behaviors. A movement disorder or other neurodegenerative impairment may include symptoms such as, for example, muscle control impairment, motion impairment, or other movement problems, such as rigidity, spasticity, bradykinesia, rhythmic hyperkinesia, nonrhythmic hyperkinesia, and akinesia. In some cases, the movement disorder may be a symptom of Parkinson’s disease. However, the movement disorder may be attributable to other patient conditions.

[0030] Example therapy system 100 A includes external device 104, IMD 106, lead extension 110, one or more leads 114A and 114B with respective sets of one or more electrodes 116, 118. In the example shown in FIG. 1, electrodes 116, 118 of leads 114 A, 114B are positioned to deliver electrical stimulation to a tissue site within brain 120, such as a deep brain site under the dura mater of brain 120 of patient 112. In some examples, delivery of stimulation to one or more regions of brain 120, such as the subthalamic nucleus, globus pallidus or thalamus, may be an effective treatment to manage movement disorders, such as Parkinson’s disease. Some or all of electrodes 116, 118 also may be positioned to sense neurological brain signals within brain 120 of patient 112. In some examples, some of electrodes 116, 118 may be configured to sense neurological brain signals and others of electrodes 116, 118 may be configured to deliver adaptive electrical stimulation to brain 120. In other examples, all of electrodes 116, 118 are configured to both sense neurological brain signals and deliver adaptive electrical stimulation to brain 120. In some examples, unipolar stimulation may be possible where one electrode is on the housing of IMD 106.Docket No.: A0012656W001 / 1123-837WO01

[0031] IMD 106 includes a therapy module (e.g., processing circuitry, signal generation circuitry or other electrical circuitry configured to perform the functions attributed to IMD 106) that includes a stimulation generator configured to generate and deliver electrical stimulation therapy to patient 112 via a subset of electrodes 116, 118 of leads 114A and 114B, respectively. The subset of electrodes 116, 118 that are configured to deliver electrical stimulation to patient 112, and, in some cases, the polarity of the subset of electrodes 116, 118, may be referred to as a stimulation electrode combination. The stimulation electrode combination may be selected for a particular patient 112 and target tissue site (e.g., selected based on the patient condition). The group of electrodes 116, 118 includes at least one electrode and may include a plurality of electrodes. In some examples, the plurality of electrodes 116 and / or 118 may have a complex electrode geometry such that two or more electrodes are located at different positions around the perimeter of the respective lead.

[0032] In some examples, neurological signals sensed within brain 120 may reflect changes in electrical current produced by the sum of electrical potential differences across brain tissue. Examples of neurological brain signals include, but are not limited to, bioelectric signals generated from local field potentials (LFP) sensed within one or more regions of brain 120. LFPs may vary overtime following implantation of leads 114A, 114B due to micro lesioning as a result of the implantation of leads 114 A, 114B. Specifically, when leads 114, 114B are inserted into the brain, there may be localized cell death as a result of the insertion. Such localized cell death may result in varying signals and / or varying responses to stimulation overtime until the area heals. The LFPs may change in the vicinity of leads 114A, 114B as a result of encapsulation of leads 114A, 114B due to immune system reactions of the patient. Electroencephalogram (EEG) signal or an electrocorticogram (ECoG) signal are also examples of bioelectric signals. For example, neurons generate the bioelectric signals in examples such as extracellular signals may be recorded via LFPs (at depth or on the surface of the cortex, typically with penetrating arrays), ECoGs (a farther signal typically recorded with disc electrodes placed subdurally), or EEGs (a farther field placed on the scalp). In other examples, IMD 106 may sense evoked signals, such as evoked compound action potentials (ECAPs), evoked resonant neural activity (ERNA), etc.

[0033] Electrical stimulation generated by IMD 106 may be configured to manage a variety of disorders and conditions. In some examples, the stimulation generator of IMD 106 is configured to generate and deliver electrical stimulation pulses to patient 112 via electrodes of a selected stimulation electrode combination. However, in other examples, the stimulation generator of IMD 106 may be configured to generate and deliver a continuous wave signal,Docket No.: A0012656W001 / 1123-837WO01 e.g., a sine wave or triangle wave. In either case, a stimulation generator within IMD 106 may generate the electrical stimulation therapy for DBS according to a selected therapy program. In examples in which IMD 106 delivers electrical stimulation in the form of stimulation pulses, a therapy program may include a set of therapy parameter values (e.g., stimulation parameters), such as a stimulation electrode combination for delivering stimulation to patient 112, pulse frequency, pulse width, and a current or voltage amplitude of the pulses. As previously indicated, the electrode combination may indicate the specific electrodes 116, 118 that are selected to deliver stimulation signals to tissue of patient 112 and the respective polarities of the selected electrodes. The electrical stimulation generated by IMD 106 may generate, for example, burst pulses, interleaved pulses, or concurrent pulses.

[0034] In some examples, electrodes 116, 118 may be radially-segmented DBS arrays (rDBSA) of electrodes. Radially-segmented DBS arrays refer to electrodes that are segmented radially along the lead. As one example, leads 114A and 114B may include a first set of electrodes arranged circumferentially around leads 114A and 114B that are all at the same height level on leads 114A and 114B. Each of the electrodes in the first set of electrodes is a separate segmented electrode and form a level of radially-segmented array of electrodes. Leads 114A and 114B may include a second set of electrodes arranged circumferentially around leads 114A and 114B that are all at the same height level on leads 114A and 114B. Each of the electrodes in the first set of electrodes is a separate segmented electrode and form a level of radially-segmented array of electrodes. The rDBSA electrodes may be beneficial for directional stimulation and sensing.

[0035] IMD 106 may be implanted within a subcutaneous pocket above the clavicle, on or within cranium 122, or at any other suitable site within patient 112. Generally, IMD 106 is constructed of a biocompatible material that resists corrosion and degradation from bodily fluids. IMD 106 may include a hermetic housing. As shown in FIG. 1 A, implanted lead extension 110 is coupled to IMD 106 via connector 108 (also referred to as a connector block or a header of IMD 106). In the example of FIG. 1 A, lead extension 110 traverses from the implant site of IMD 106 and along the neck of patient 112 to cranium 122 of patient 112 to access brain 120.

[0036] In the example shown in FIG. 1 A, leads 114A and 114B (collectively “leads 114”) are implanted within the right and left hemispheres (or in just one hemisphere in some examples), respectively, of patient 112 in order to deliver electrical stimulation to one or more regions of brain 120, which may be selected based on the patient condition or disorder controlled by therapy system 100A. The specific target tissue site and the stimulationDocket No.: A0012656W001 / 1123-837WO01 electrodes configured to deliver stimulation to the target tissue site, however, may be selected, e.g., according to the identified patient behaviors and / or other sensed patient parameters. For example, the target tissue site may be the location of the oscillatory signal source that generates the bioelectric signal including a signal component in the beta frequency band. The stimulation electrodes configured to deliver stimulation to the target tissue site may be those that are most proximal to the oscillatory signal source, e.g., using the example techniques described in this disclosure. Other lead 114, lead extension 110, and IMD 106 implant sites are contemplated depending on clinical application or target tissue / nerve. For example, IMD 106 may be implanted on or within cranium 122, in some examples. Leads 114A and 114B may be implanted within the same hemisphere or IMD 106 may be coupled to a single lead implanted in a single hemisphere, in some examples.

[0037] Existing lead sets include axial leads carrying ring electrodes disposed at different axial positions and so-called "paddle" leads carrying planar arrays of electrodes. Selection of electrode combinations within an axial lead, a paddle lead, or among two or more different leads by the clinician may enable the clinician to modulate the delivered therapy. In some examples, more complex lead array geometries may be suitable. Pelvic stimulation may use cuff electrodes wrapped around the sacral (or other pelvic) nerve.

[0038] Although leads 114 are shown in FIG. 1 A as being coupled to a common lead extension 110, in other examples, leads 114 may be coupled to IMD 106 via separate lead extensions or directly to connector 108. Leads 114 may be positioned to deliver electrical stimulation to one or more target tissue sites within brain 120 to manage patient symptoms associated with a movement disorder of patient 112. Leads 114 may be implanted to position electrodes 116, 118 at suitable locations of brain 120 through respective holes in cranium 122. Leads 114 may be placed at any location within brain 120 such that electrodes 116, 118 are capable of providing electrical stimulation to target tissue sites within brain 120 during treatment. For example, electrodes 116, 118 may be surgically implanted under the dura mater of brain 120 or within the cerebral cortex of brain 120 via a burr hole in cranium 122 of patient 112, and electrically coupled to IMD 106 via one or more leads 114.

[0039] In the example shown in FIG. 1 A, electrodes 116, 118 of leads 114 are shown as ring electrodes. Ring electrodes may be used in DBS applications because ring electrodes are relatively simple to program and are capable of delivering an electrical field to any tissue adjacent to electrodes 116, 118. In other examples, electrodes 116, 118 may have different configurations. For example, at least some of the electrodes 116, 118 of leads 114 may have a complex electrode array geometry that is capable of producing shaped electrical fields. TheDocket No.: A0012656W001 / 1123-837WO01 complex electrode array geometry may include multiple electrodes (e.g., partial ring or segmented electrodes) around the outer perimeter of each lead 114, rather than one ring electrode. In this manner, electrical stimulation may be directed in a specific direction from leads 114 to enhance therapy efficacy and reduce possible adverse side effects from stimulating a large volume of tissue.

[0040] In some examples, a housing of IMD 106 may include one or more stimulation and / or sensing electrodes. In some examples, leads 114 may have shapes other than elongated cylinders as shown in FIG. 1 A. For example, leads 114 may be paddle leads, spherical leads, bendable leads, or any other type of lead or shape of lead effective in treating patient 112, minimizing invasiveness of leads 114, and / or as suitably selected by the clinician.

[0041] IMD 106 includes a memory to store a plurality of therapy programs that each define a set of therapy parameter values. In some examples, IMD 106 may select a therapy program from the memory based on various parameters, such as sensed patient parameters and the identified patient behaviors. IMD 106 may generate electrical stimulation based on the parameters of the selected therapy program to manage the patient symptoms associated with a movement disorder.

[0042] External device 104 wirelessly communicates with IMD 106 as needed to provide or retrieve therapy information. External device 104 is an external computing device that the user, e.g., a clinician / clinician and / or patient 112, may use to communicate with IMD 106. For example, external device 104 may be a clinician programmer that the clinician / clinician uses to communicate with IMD 106 and program one or more therapy programs for IMD 106. External device 104 may be a patient programmer that enables patient 112 to select programs and / or view and modify therapy parameters. The clinician programmer may include more programming features than the patient programmer. In other words, more complex or sensitive tasks may only be enabled on the clinician programmer to deny an untrained patient from making unsuitable changes to IMD 106. External device 104 may be any type of computing device, such as a proprietary device, a cellular phone, a smartphone, a tablet computing device, a laptop, or any other type of computing device. Generally, external device 104 includes a user interface that may provide and / or receive information from a user. In some examples, external device 104 may be configured to pass information between IMD 106 and a different external device 104, but external device 104 may or may not have a user interface for programming. Instead, external device 104 may receive programming commands from a different external device 104 (e.g., a server or other computing device thatDocket No.: A0012656W001 / 1123-837WO01 includes a user interface) and transmit those programming commands to IMD 106 and / or receive information from IMD 106 and send that information to the different external device.

[0043] When external device 104 is configured for use by the clinician, external device 104 may be configured to transmit initial programming information to IMD 106. This initial information may include hardware information, such as the type of leads 114 and the electrode arrangement, the position of leads 114 within brain 120, the configuration of electrode array 116, 118, initial programs defining therapy parameter values, and any other suitable information to program into IMD 106 for control thereof. External device 104 may also be capable of completing functional tests (e.g., measuring the impedance of electrodes 116, 118 of leads 114).

[0044] the clinician may also store therapy programs within IMD 106 with the aid of external device 104. During a programming session, the clinician may determine one or more therapy programs that may provide efficacious therapy to patient 112 to address symptoms associated with the patient condition, and, in some cases, specific to one or more different patient states, such as a sleep state, movement state, or rest state. For example, the clinician may select one or more stimulation electrode combinations with which stimulation is delivered to brain 120. The clinician may additionally or alternatively adopt one or more stimulation electrode combinations that are default settings with which stimulation is delivered to brain 120. During the programming session, the clinician may evaluate the efficacy of the specific program being evaluated based on feedback provided by patient 112 or based on one or more physiological parameters of patient 112 (e.g., muscle activity, muscle tone, rigidity, tremor, etc.). Identified patient behavior from video information may be used as feedback during the initial and subsequent programming sessions. External device 104 may assist the clinician in the creation / identification of therapy programs by providing a methodical system for identifying potentially beneficial therapy parameter values.

[0045] However, in some examples, IMD 106 or external device 104 (e.g., a clinician programmer, a patient programmer, a recharger, a programmer fob, etc.), alone or in combination, may automatically determine electrode configuration and therapy parameters. For example, processing circuitry of IMD 106 may ascertain which electrodes to use for stimulation based on which electrodes are most proximal to target tissue. In some examples, the sensing circuitry may continuously record the local field potentials after implantation of leads 114 A, 114B and may select the electrode configuration for stimulation and the determined stimulation amplitude or other therapy parameter based on one or more metrics of the local field potentials. In some examples, external device 104 may output informationDocket No.: A0012656W001 / 1123-837WO01 indicating the selected electrode configuration for stimulation and the determined stimulation amplitude or other therapy parameter for the clinician (e.g., clinician, physician, nurse, physician’s assistant) to review and confirm before IMD 106 delivers therapy via the selected electrode configuration with the determined stimulation amplitude.

[0046] External device 104 may be specifically configured for use by a clinician. In some examples, external device 104 may output information indicating the time since implant, the implant status, the convergence status, and metric indications. The external device 104 may additionally or alternatively output information indicating whether the clinician should expect changes in therapy performance, whether the lead-tissue interface is stabilizing, and whether the lead-tissue interface is stabilized. The external device 104 may additionally or alternatively output information of each metric of the external device 104 and whether the metric has stabilized, converged, increased, decreased, or otherwise satisfied a metric.

[0047] External device 104 may also be configured for use by patient 112. When configured as a patient programmer, external device 104 may have limited functionality (compared to a clinician programmer) in order to deny patient 112 from altering critical functions of IMD 106 or applications that may be undesirable to patient 112. In this manner, external device 104 may only enable patient 112 to adjust values for certain therapy parameters or set an available range of values for a particular therapy parameter. For example, external device 104 may only enable patient 112 to adjust an amplitude or an intensity (by combination of any one or more of amplitude, pulse width and / or pulse rate).

[0048] External device 104 may also provide an indication to patient 112 when therapy is being delivered, when patient input has triggered a change in therapy, when the power source within external device 104 or IMD 106 needs to be replaced or recharged, when the electrode-tissue interface has stabilized, a request for the patient to contact their clinician, or any other suitable notification to alter functioning or functionality of external device 104 and IMD 106. For example, external device 104 may include an alert LED and / or a touchscreen, may flash a message to patient 112 via a programmer display, generate an audible sound or somatosensory cue to confirm patient input was received, e.g., to indicate a patient state or to manually modify a therapy parameter. External device 104 may additionally or alternatively include a user interface that may include a screen.

[0049] Therapy system 100 A may be implemented to provide chronic stimulation therapy to patient 112 over the course of several months or years. However, system 100 A may also be employed on a trial basis to evaluate therapy before committing to full implantation.Docket No.: A0012656W001 / 1123-837WO01System 100 A implemented on a trial basis may continuously record the LFPs of the implantation site to determine if the selected implantation site stabilizes, or satisfies any other metric of neuronal signals sensed by the sensing circuitry, and therefore whether the site is appropriate for chronic implantation. If implemented temporarily, portions of system 100 A may not be implanted within patient 112. For example, patient 112 may be fitted with an external medical device, such as a trial stimulator, rather than IMD 106. The external medical device may be coupled to percutaneous leads or to implanted leads via a percutaneous extension. If the trial stimulator indicates DBS system 100 A provides effective treatment to patient 112, the clinician may implant a chronic stimulator within patient 112 for relatively long-term treatment.

[0050] In some examples, IMD 106 may be configured to provide electrical stimulation for treatment of a patient condition supplemental to medication provided to patient 122. Although some examples are described with the use of IMD 106 that provides stimulation, the techniques are not limited, and the techniques may apply to examples where no stimulation is provided. For example, IMD 106 may temporarily not provide stimulation and treatment of a patient condition of patient 122 if patient 112 is treated by medication or with other techniques. IMD 106 may use LFP to determine medication for one disorder of patient 122 and may apply stimulation for any suitable disorder of patient 122. For example, patient 122 may have a dual disease like Parkinson’s disease and dystonia and leads 114 are in locations to treat both Parkinson’s disease and dystonia. A single IMD 106 may listen / monitor to different LFP bands to look at various medication or disease states via the same lead / same hemisphere or different hemispheres.

[0051] According to the techniques of the disclosure, external device 104 (e.g., a clinician programmer, a patient programmer, a recharger, a programmer fob, etc.) may be configured to output feedback to a user of external device 104 based on an electrode-tissue interface status. Techniques described herein may improve patient experience by decreasing a time between implantation and therapy delivery. Techniques described herein may improve patient experience by adapting the delivered stimulation based on the recorded metrics.

[0052] Stimulation generation circuitry may be configured to deliver electrical stimulation therapy according to a therapy schedule. The therapy schedule may refer to the instructions that define when IMD 106 is to deliver therapy according to one or more therapy programs. A therapy program may define a set of stimulation parameters that define the electrical stimulation delivered, such as electrode combination, current or voltage amplitude, pulse width, pulse frequency, duty cycle, burst frequency, burst duration, pulse shape, etc.Docket No.: A0012656W001 / 1123-837WO01Therefore, IMD 106 may deliver stimulation therapy defined by the one or more therapy programs during a therapy session. The therapy schedule may define when IMD 106 is to begin and / or end a therapy session. In some examples, the therapy schedule may be or may include a therapy calendar defining delivery of the electrical stimulation therapy at specific calendar days of the therapy calendar. For example, a therapy calendar may specify that IMD 106 should execute a therapy session every Tuesday and Friday of each week, or during specific calendar days of a month, and at particular times of those specified days. In other examples, the therapy schedule includes a therapy cycle defining a repeating pattern of delivery of the electrical stimulation therapy and non-delivery of the electrical stimulation therapy. For example, the therapy cycle may specify that a therapy session is to be repeated every predetermined number of hours or initiated again after a predetermined interval from the end of the last therapy session. In some examples, the therapy schedule may include a combination of the therapy calendar and therapy cycle. In other examples, the therapy schedule may include or be augmented by sensed patient parameters that trigger the delivery, or termination of, stimulation therapy.

[0053] In some examples, IMD 106 may enter a sleep mode in which the telemetry circuitry and / or processing circuitry enter a low power mode and advertisement packets are no longer transmitted (or transmitted at very long intervals such as on the order of many minutes or hours). In some examples, the communication advertisement packets may be or include Bluetooth™ advertisement packets. IMD 106 may monitor an internal timer and exit the sleep mode to begin transmitting advertisement packets again once the sleep mode has been exited. A magnetic field detector (e.g., a hall sensor) may detect an external magnet that a user places near IMD 106 and IMD 106 may wake-up in response to receiving that signal generated by the magnetic field detector. Other sensors signals that IMD 106 may monitor to wake-up communications may include an output from an accelerometer, an output from a sound sensor, or an output from a temperature sensor. Responsive to receiving the wake-up signal, IMD 106 may control the telemetry circuitry to initiate the transmission of the communication advertisement packets.

[0054] FIG. IB is a conceptual diagram illustrating an example system 100B that includes an implantable medical device (IMD) 124 configured to deliver spinal cord stimulation (SCS) therapy to a spinal cord 128 of a patient 112 and an external device 104, in accordance with one or more techniques of this disclosure. 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,Docket No.: A0012656W001 / 1123-837WO01 implantable electrical stimulators (e.g., neurostimulators) will be described for purposes of illustration. More particularly, the disclosure will refer to an implantable SCS system for purposes of illustration, but without limitation as to other types of medical devices or other therapeutic applications of medical devices.

[0055] As shown in FIG. IB, system 100B includes an IMD 124, leads 126A and 126B, and external device 104 shown in conjunction with patient 112, who is ordinarily a human patient. In the example of FIG. IB, IMD 124 is an implantable electrical stimulator that is configured to generate and deliver electrical stimulation therapy to patient 112 via one or more electrodes of electrodes of leads 126A and / or 126B (collectively, “leads 126”), e.g., for relief of chronic pain or other symptoms. In other examples, IMD 124 may be coupled to a single lead carrying multiple electrodes or more than two leads each carrying multiple electrodes. Some or all of leads 126 also may be positioned to sense spinal cord signals of spinal cord 128 of patient 112. In some examples, some of electrodes on leads 126 may be configured to sense neurological signals and others of electrodes on leads 126 may be configured to deliver adaptive electrical stimulation to spinal cord 128. In other examples, all of the electrodes on leads 126 are configured to both sense neurological signals and deliver adaptive electrical stimulation to spinal cord 128. In some examples, unipolar stimulation may be possible where one electrode is on the housing of IMD 124.

[0056] In some examples, neurological signals sensed at or near spinal cord 128 may reflect changes in electrical current produced by the sum of electrical potential differences generated by spinal tissue proximate leads 126. Examples of spinal signals include, but are not limited to, Evoked Compound Action Potentials (ECAPs) sensed near one or more regions of spinal cord 128. In or near the spinal cord, healing around electrode implantation may include an immune response and encapsulation. Although this may be different than micro lesioning, the healing process may still cause the ECAPs to similarly vary overtime following implantation of leads 126. ECAPs may change in the vicinity of leads 126 as a result of encapsulation of leads 126 due to immune system reactions of the patient. In other examples, IMD 124 may sense evoked signals, such as evoked compound action potentials (ECAPs), evoked synaptic action potentials (ESAPs), etc. In some examples, IMD 124 uses one or more leads, while in other examples, IMD 124 is leadless.

[0057] IMD 124 may be constructed of any polymer, metal, or composite material sufficient to house the components of IMD 124 (e.g., components illustrated in FIG. 2) within patient 112. In this example, IMD 124 may be constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material such as silicone, polyurethane, or aDocket No.: A0012656W001 / 1123-837WO01 liquid crystal polymer, and surgically implanted at a site in patient 112 near the pelvis, abdomen, or buttocks. In other examples, IMD 124 may be implanted within other suitable sites within patient 112, which may depend, for example, on the target site within patient 112 for the delivery of electrical stimulation therapy. The outer housing of IMD 124 may be configured to provide a hermetic seal. IMD 124 may include a power source within the hermetic seal, such as a rechargeable or non-rechargeable power source. The power source may include a battery such as a lithium-ion battery or any other power source suitable to powering IMD 124. In addition, in some examples, the outer housing of IMD 124 is selected from a material that facilitates receiving energy to charge the rechargeable power source.

[0058] Electrical stimulation energy (e.g., constant current or constant voltage-based pulses) may delivered from IMD 124 to one or more target tissue sites of patient 112 via one or more electrodes (not shown) of implantable leads 126. In the example of FIG. IB, leads 126 carry electrodes that are placed adjacent to the target tissue of spinal cord 128. One or more of the electrodes may be disposed at a distal tip of a lead 126 and / or at other positions at intermediate points along the lead. Leads 126 may be implanted and coupled to IMD 124. The electrodes may transfer electrical stimulation generated by an electrical stimulation generator in IMD 124 to tissue of patient 112. Although leads 126 may each be a single lead, lead 126 may include a lead extension or other segments that may aid in implantation or positioning of leads 126. In some other examples, IMD 124 may be a leadless stimulator with one or more arrays of electrodes arranged on a housing of the stimulator rather than leads (e.g., leads 126) that extend from the housing. In addition, in some other examples, system 100B may include one lead or more than two leads, each coupled to IMD 124 and directed to similar or different target tissue sites.

[0059] The electrodes of leads 126 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. Ring electrodes arranged at different axial positions at the distal ends of leads 126 will be described for purposes of illustration.

[0060] The deployment of electrodes via leads 126 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 / orDocket No.: A0012656W001 / 1123-837WO01 columns (or other patterns), to which shifting operations may be applied. Such electrodes may be arranged as surface electrodes, ring electrodes, or protrusions. In some examples, electrode arrays are 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 126 are linear leads that may include 8 ring electrodes along the axial length of the lead. In some examples, the electrodes are segmented rings arranged in a linear fashion along the axial length of the lead and at the periphery of the lead.

[0061] The stimulation parameter set of a therapy stimulation program that defines the stimulation pulses of electrical stimulation therapy by IMD 124 through the electrodes of leads 126 may include information identifying whether the electrodes are ready for stimulation therethrough, 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, voltage or current amplitude, pulse frequency, pulse width, pulse shape of stimulation delivered by the electrodes. These stimulation parameters values that make up the stimulation parameter set that defines pulses may be predetermined parameter values defined by a user and / or automatically determined by system 100 based on one or more factors or user input.

[0062] Although FIG. IB is directed to SCS therapy, e.g., used to treat pain, in other examples system 100B may be configured to treat any other condition that may benefit from electrical stimulation therapy. For example, system 100B may be configured to treat 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 100B 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 112.

[0063] In some examples, lead 126 includes one or more sensors configured to enable IMD 124 to monitor one or more parameters of patient 112, 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 lead 126.Docket No.: A0012656W001 / 1123-837WO01

[0064] IMD 124 is configured to deliver electrical stimulation therapy to patient 112 via selected combinations of electrodes carried by one or both of leads 126, alone or in combination with an electrode carried by or defined by an outer housing of IMD 124. 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. In some examples, the target tissue includes nerves, smooth muscle or skeletal muscle. In the example illustrated by FIG. 1, the target tissue is tissue proximate spinal cord 128, such as within an intrathecal space or epidural space of spinal cord 128, or, in some examples, adjacent nerves that branch off spinal cord 128. Leads 126 may be in any suitable region of spinal cord 128, such as the thoracic, cervical or lumbar regions. Stimulation of spinal cord 128 may, for example, prevent, reduce, or limit pain signals from traveling through spinal cord 128 and to the brain of patient 112. Patient 112 may perceive the interruption of pain signals as a reduction in pain and, therefore, efficacious therapy results. In other examples, stimulation of spinal cord 128 may produce paresthesia that may be reduce the perception of pain by patient 112, and thus, provide efficacious therapy results.

[0065] IMD 124 is configured to generate and deliver electrical stimulation therapy to a target stimulation site within patient 112 via the electrodes of leads 126 to patient 112 according to one or more therapy stimulation programs. A therapy stimulation program defines values for one or more parameters (e.g., a parameter set) that define an aspect of the therapy delivered by IMD 124 according to that program. For example, a therapy stimulation program that controls delivery of stimulation by IMD 124 in the form of pulses may define values for voltage or current pulse amplitude, pulse width, pulse rate (e.g., pulse frequency), electrode combination, pulse shape, etc. for stimulation pulses delivered by IMD 124 according to that program.

[0066] A user, such as the clinician or patient 112, may interact with a user interface of external device 104 to program IMD 124. Programming of IMD 124 may refer generally to the generation and transfer of commands, programs, or other information to control the operation of IMD 124. In this manner, IMD 124 may receive the transferred commands and programs from external device 104 to control stimulation, such as electrical stimulation therapy (e.g., informed pulses) and / or control stimulation (e.g., control pulses). For example, external device 104 may transmit therapy stimulation programs, test stimulation programs, stimulation parameter adjustments, therapy stimulation program selections, test program selections, user input, or other information to control the operation of IMD 124, e.g., by wireless telemetry or wired connection.Docket No.: A0012656W001 / 1123-837WO01

[0067] In some cases, external device 104 may be characterized as a physician or clinician programmer if it is primarily intended for use by the clinician. In other cases, external device 104 may be characterized as a patient programmer if it is primarily intended for use by patient 112. A patient programmer may be generally accessible to patient 112 and, in many cases, may be a portable device that may accompany patient 112 during the patient’s daily routine. For example, a patient programmer may receive input from patient 112 when the patient wishes to terminate or change electrical stimulation therapy, or when a patient perceives stimulation being delivered. In general, a physician or clinician programmer may support selection and generation of programs by the clinician for use by IMD 124, whereas a patient programmer may support adjustment and selection of such programs by patient 112 during ordinary use. In other examples, external device 104 may include, or be part of, an external charging device that recharges a power source of IMD 124. In this manner, a user may program and charge IMD 124 using one device, or multiple devices.

[0068] As described herein, information may be transmitted between external device 104 and IMD 124. Therefore, IMD 124 and external device 104 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 device 104 includes a communication head that is placed proximate to patient’s 112 body near the IMD 124 implant site to improve the quality or security of communication between IMD 124 and external device 104. Communication between external device 104 and IMD 124 may occur during power transmission or separate from power transmission.

[0069] In some examples, IMD 124, in response to commands from external device 104, delivers electrical stimulation therapy according to a plurality of therapy stimulation programs to a target tissue site of the spinal cord 128 of patient 112 via electrodes (not depicted) on leads 126. In some examples, IMD 124 modifies therapy stimulation programs as therapy needs of patient 112 evolve over time. When patient 112 receives the same therapy for an extended period, the efficacy of the therapy may be reduced. As an electrodetissue interface of patient 112 heals, the efficacy of the therapy may change overtime. In some cases, parameters of the plurality of therapy stimulation programs may be automatically updated based at least in part on a change in the efficacy of the treatment overtime.

[0070] One or more devices within system 100B, such as IMD 124 and / or external device 104, may perform various functions as described herein. For example, IMD 124 may include stimulation circuitry configured to deliver electrical stimulation, sensing circuitry configuredDocket No.: A0012656W001 / 1123-837WO01 to sense signals, and processing circuitry. The processing circuitry may be configured to control the stimulation circuitry to deliver a plurality of electrical stimulation pulses having different amplitude values and control the sensing circuitry to detect, after delivery of each electrical stimulation pulse of the plurality of electrical stimulation pulses, a respective response signal of a plurality of response signals. The processing circuitry of IMD 124 may then determine, based on the plurality of response signals, a characteristic value of one or more of the respective signals. The processing circuitry of IMD 124 may then determine, based on the characteristic value, an updated stimulation parameter and / or a therapy progression indicator.

[0071] In some examples, IMD 124 includes the stimulation circuitry, the sensing circuitry, and the processing circuitry. However, in other examples, one or more additional devices may be part of the system that performs the functions described herein. For example, IMD 124 may include the stimulation circuitry and the sensing circuitry, but external device 104 or other external device may include the processing circuitry that may determines a posture state of patient 112 and / or a therapy progression metric (e.g., a convergence metric) of an electrode-tissue interface. IMD 124 may transmit the sensed signals, or data representing the signals, to external device 104, for example. Therefore, the processes described herein may be performed by multiple devices of a distributed system. In some examples, system 100B includes one or more electrodes that deliver and / or sense electrical signals. Such electrodes may be configured to sense signals. In some examples, the same electrodes are configured to sense signals representative of transient movements of patient 112. In other examples, other sensors, such as accelerometers, gyroscopes, or other movement sensors may be configured to sense movement of the patient that indicates patient 112 may have transitioned to a different posture state, by which the target characteristic value may have changed accordingly.

[0072] As described herein, the processing circuitry of IMD 124 may be configured to determine a convergence status for the plurality of signals detected after implantation. The convergence status may be based on one day of data. In some examples, the convergence status may be based on ’A of a day of data, 2 days of data, or a suitable quantity of recorded signal to reliably calculate one or more convergence metrics. Each convergence metric is a representation of a characteristic of the signal. For example, a convergence metric may be a detection of whether significant outliers are in the data, a detection of whether the data is trending upwards, whether the data is monotonically decreasing, whether the data has experienced a baseline shift, whether the data has significant outliers below limits, whetherDocket No.: A0012656W001 / 1123-837WO01 the data has alternating averages, whether the data has pattern matching, or any other characteristic in the data which indicate a current status of a microlesion, a healing of a tissue, or any other response to a microlesion.

[0073] IMD 124 or another device may also identify other electrical events from the detected electrical signals. For example, an electrocardiogram or signals of heart activity could be detected via far-field sensing. The system may identify changes to signal-to-noise ratio, power in different frequency bands, or any other information as an additional input to the convergence metric. This electrical information could be sensed via monopolar sensing from the housing of IMD 124 to a lead, a bipole of electrodes, or a plurality of electrodes.

[0074] Although in one example IMD 124 takes the form of an SCS device, in other examples, IMD 124 takes the form of any combination of deep brain stimulation (DBS) devices, implantable cardioverter defibrillators (ICDs), pacemakers, cardiac resynchronization therapy devices (CRT-Ds), left ventricular assist devices (LVADs), implantable sensors, orthopedic devices, or drug pumps, as examples. Moreover, techniques of this disclosure may be configured to determine stimulation thresholds and / or convergence statuses (e.g., perception thresholds and detection thresholds) associated any one of the aforementioned IMDs and then use the stimulation thresholds and / or convergence statuses to notify the clinician of changes to an electrode-tissue interface or to inform the intensity (e.g., stimulation levels) of therapy.

[0075] FIG. 1C is a conceptual diagram illustrating another example system 100C that includes an implantable medical device (IMD) 130 configured to deliver electrical stimulation to one or more pelvic nerves 136 of a patient 112 according to an example of the techniques of the disclosure. In the example of FIG. 1C, system 100C may be similar to systems 100A or 100B and includes IMD 130 that may be similar to IMD 106 or IMD 124. IMD 130 may be configured to deliver therapy to and / or sense physiological signals from target tissue. The target tissue may include or be near spinal cord 128 and / or pelvic nerves 136 (e.g., a pudendal nerve or sacral nerve), or any other nervous or muscle tissue that may be stimulated or from which physiological signals may be sensed of patient 112 through lead 134 (coupled to IMD 130 via connector 132). Lead 134 may carry a plurality of electrodes 138 at the distal end of lead 134. Lead 134 may be substantially similar to leads 114 of FIG. 1 A and / or leads 126 of FIG. IB. Electrodes 128 may be substantially similar to electrodes 118 of FIG. 1 A and / or the electrodes (not shown) of FIG. IB. IMD 130 may provide neurostimulation to treat symptoms of patient 112, such as pain, fecal or urinaryDocket No.: A0012656W001 / 1123-837WO01 incontinence, erectile dysfunction, or other sexual dysfunction. IMD 130 may thus be configured to provide sacral nerve stimulation in one example.

[0076] In other examples, IMD 130 may be configured to deliver electrical stimulation to other nerves that may alleviate symptoms related to pelvic floor disorders. In one example, IMD 130 may be configured to deliver electrical stimulation to the tibial nerve (e.g., tibial nerve stimulation). Electrodes 138 may be implanted near a suitable portion of the tibial nerve (e.g., a leg and / or ankle of patient 112).

[0077] FIG. 2 is a block diagram of IMD 106 of FIG. 1 A for delivering electrical stimulation according to an example of the techniques of the disclosure. In the example shown in FIG. 2, IMD 106 includes stimulation generation circuitry 202, sensing circuitry 204, telemetry circuitry 208, processing circuitry 210, memory 212, and power source 220. Each of these circuits may be electrical circuitry configured to perform the functions attributed to each respective circuit. Although FIG. 2 is described with respect to IMD 106, and associated components and target tissue structures, of FIG. 1A, the examples described with respect to FIG. 2 are generally applicable to a variety IMDs and their associated components and target tissue structures (such as IMD 124 of system 100B of FIG. IB or IMD 130 of system 100C of FIG. 1C), application of such techniques to IMD 106 and, more particularly, implantable electrical stimulators (e.g., neurostimulators for deep brain stimulation) will be described for purposes of illustration.

[0078] Memory 212 may include any volatile or non-volatile media, such as a randomaccess memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), ferroelectric RAM (FRAM), electrically erasable programmable ROM (EEPROM), flash memory, and the like. Memory 212 may store computer-readable instructions that, when executed by processing circuitry 210, cause IMD 106 to perform various functions. Memory 212 may be a storage device or other non-transitory medium. In the example shown in FIG. 2, memory 212 stores electrical stimulation information 214. Electrical stimulation information 214 may include program parameters (e.g., a therapy parameter set), such as a stimulation electrode combination, electrode polarity, current or voltage amplitude, pulse width, and pulse rate. In some examples, individual therapy programs may be stored as a therapy group, which defines a set of therapy programs with which stimulation may be generated during a therapy session in which stimulation therapy is delivered. The stimulation signals defined by the therapy programs of the therapy group may be delivered together on an overlapping or non-overlapping (e.g., time-interleaved) basis, the example shown in FIG. 2, memory 212 additionally stores convergence analysis algorithm 216 that may detect aDocket No.: A0012656W001 / 1123-837WO01 convergence status of the recorded signals. The convergence status may be based on any signal and / or one or more convergence metrics of the signal. Convergence detection algorithm 216 may run on processing circuitry 210 and send a signal to telemetry circuitry 208 and / or commence stimulation generation circuitry’s 202 generation of signals.

[0079] Accordingly, in some examples, stimulation generation circuitry 202 may generate electrical stimulation signals in accordance with the electrical stimulation parameters noted above, which may be examples of program parameters. Other ranges of therapy parameter values may also be useful and may depend on the target stimulation site within patient 112. While stimulation pulses are described, stimulation signals may be of any form, such as continuous-time signals (e.g., sine waves) or the like. Stimulation generation circuitry 202 is an example of therapy circuitry configured to deliver a therapy from IMD 106. In other examples, therapy circuitry may include circuitry configured to control and / or deliver other therapies, such as a fluid that contains one or more drugs (e.g., insulin, pain relievers, behavioral drugs, etc.). In this manner, the therapy circuitry may control one or more pumps to deliver the drug from IMD 106. Other types of therapies may additionally, or alternatively, be delivered using therapy circuitry and IMD 106.

[0080] Processing circuitry 210 may include fixed function processing circuitry and / or programmable processing circuitry, and may include, for example, 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 may control stimulation generation circuitry 202 according to therapy programs stored in electrical stimulation information 214 of memory 212 to apply particular stimulation parameter values specified by one or more of programs, such as voltage amplitude or current amplitude, pulse width, and / or pulse rate.

[0081] In the example shown in FIG. 2, the set of electrodes 116 includes electrodes 116A, 116B, 116C, and 116D of FIG. 1 A, and the set of electrodes 118 includes electrodes 118A, 118B, 118C, and 118D of FIG. 1 A. Although FIG. 2 is described with respect to electrodes 116 and 118 of FIG. 1 A, the examples described with respect to FIG. 2 are generally applicable to a variety leads and electrodes (such as leads 126 or electrodes (not shown) of system 100B of FIG. IB or lead 134 or electrodes 138 of system 100C of FIG. 1C), application of such techniques to electrodes 116 and 118 of FIG. 1 A and, more particularly, implantable electrical stimulators (e.g., neurostimulators for deep brainDocket No.: A0012656W001 / 1123-837WO01 stimulation) will be described for purposes of illustration. Processing circuitry 210 may control individual voltage or current sources and sinks coupled to respective electrodes 116, 118, functioning as cathodes or anodes, to deliver stimulation signals to patient tissue. In other examples, processing circuitry may control switch circuitry to apply the stimulation signals generated by stimulation generation circuitry 202 to selected combinations of electrodes 116, 118.

[0082] Stimulation generation circuitry 202 may be a single channel or multi-channel stimulation generator. Stimulation generation circuitry 202 may be capable of delivering a single stimulation pulse, multiple stimulation pulses, or a continuous signal at a given time via a single electrode combination or multiple stimulation pulses at a given time via multiple electrode combinations. For example, as mentioned above, stimulation generation circuitry 202 may include multiple voltage or current sources and sinks that are coupled to respective electrodes to drive the electrodes as cathodes or anodes simultaneously or at different times, switch circuitry may or may not be suitable for time-interleaved multiplexing of stimulation via different electrodes. In other examples, however, stimulation generation circuitry 202 may be configured to deliver multiple channels on a time-interleaved basis. In some examples, switch circuitry may time divide the output of stimulation generation circuitry 202 across different electrode combinations at different times to deliver multiple programs or channels of stimulation energy to patient 112.

[0083] Telemetry circuitry 208 supports wireless communication using one or more communication protocols (e.g., Radio Frequency Communication Protocols, Bluetooth™, Wi-Fi™, Near-Field Communication (NFC), Near Field Magnetic Induction (NFMI), Long Term Evolution, 5th generation (LTE / 5G), or MedRadio (MICS: Medical Implant Communication Service, MEDS: Medical External Device Service, MB AD: Medical Body Area Network)) between IMD 106 and an external device 104 or any suitable computing device under the control of processing circuitry 210. In some examples, telemetry circuitry 208 supports a telemetry frequency that may correspond to a high frequency or radio frequency, which may be a radio frequency established via Bluetooth™, Wi-Fi™, Near-Field Communication (NFC), 175KHz inductive telemetry, or MICS, for example. Telemetry circuitry 208 may be configured to receive an inductive sting. Processing circuitry 210 of IMD 106 may receive, as updates to programs (e.g., at least one program parameter), values for various stimulation parameters such as magnitude and electrode combination, from external device 104 via telemetry circuitry 208. The updates to the therapy programs may be stored within electrical stimulation information 214 portion of memory 212. TelemetryDocket No.: A0012656W001 / 1123-837WO01 circuitry 208 in IMD 106, as well as telemetry modules in other devices and systems described herein, such as external device 104, may accomplish communication by radiofrequency (RF) communication techniques (e.g., Bluetooth™, Wi-Fi, Near-Field Communication (NFC), or MICS). In addition, telemetry circuitry 208 may communicate with external device 104 via proximal inductive interaction of IMD 106 with external device 104. Accordingly, telemetry circuitry 208 may send information to external device 104 on a continuous basis, at periodic intervals, or upon request from IMD 106 or external device 104.

[0084] Telemetry circuitry 208 enables communications between IMD 106 (e.g., a medical device or an implantable medical device (IMD)) and external devices (e.g., external device 104 of FIGS. 1 A-1C, a patient programmer, a clinician programmer, an application on mobile device) configured to provide monitoring and / or therapy to a patient, which may include electrical stimulation therapy (e.g., neuromodulation such as deep brain stimulation (DBS), spinal cord stimulation (SCS), sacral nerve stimulation (SNS), or peripheral nerve stimulation therapy). The external devices may be able to configure or adjust program parameters on the first device. Bluetooth™ is an example radio frequency communication (RFC) protocol that may be implemented by telemetry circuitry 208 because it enables direct, wireless, arms-length or greater distance connections to other implanted or external devices, which may include mobile phones and tablet computing devices.

[0085] Power source 220 may deliver operating power to IMD 106. Power source 220 may include a small rechargeable or non-rechargeable battery and a power generation circuit to produce the operating power. Recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within IMD 106. In some examples, power requirements may be small enough to enable IMD 106 to utilize patient motion and implement a kinetic energy-scavenging device to trickle charge a rechargeable battery. In other examples, traditional batteries may be used as a sole power source or in addition to any other suitable power source.

[0086] Processing circuitry 210 of IMD 106 may sense, via electrodes 116, 118 interposed along leads 114 (and sensing circuitry 204), one or more bioelectric signals of patient 112 (e.g., brain signals, spinal cord signals, or any other signals from patient 112). Processing circuitry 210 of IMD 106 may deliver, via electrodes 116, 118 (and stimulation generation circuitry 202), electrical stimulation therapy to patient 112 based on the sensed one or more bioelectric signals of brain 120. The adaptive DBS therapy is defined by electrical stimulation information 214. For example, electrical stimulation information 214 may include a current amplitude (for a current-controlled system) or a voltage amplitude (forDocket No.: A0012656W001 / 1123-837WO01 a voltage-controlled system), a pulse rate or frequency, a pulse width, and / or a number of pulses per cycle. In examples where the electrical stimulation is delivered according to a “burst” of pulses, or a series of electrical pulses defined by an “on-time” and an “off-time,” the one or more parameters may define one or more of pulses per burst, an on-time, and an off-time. Processing circuitry 210, via electrodes 116, 118, delivers to patient 112 adaptive DBS and may adjust one or more parameters defining the electrical stimulation based on corresponding parameters of the sensed one or more bioelectric signals of brain 120.

[0087] In some examples, processing circuitry 210 may continuously measure the one or more bioelectric signals in real time. In other examples, processing circuitry 210 may periodically sample the one or more bioelectric signals according to a predetermined frequency or after a predetermined amount of time. In some examples, processing circuitry 210 may periodically sample the signal at a frequency of one sample every 10 minutes. Other sampling rates, such as every few minutes, every hour, etc. may be used in other examples as appropriate for the system and / or patient conditions. Such a sampling rate may result in lower power consumption than faster sampling rates while enabling detection and classification of trends in the data. In other examples, processing circuitry 210 may periodically sample the signal at a frequency of one sample every minute.

[0088] In some examples, processing circuitry 210 may continuously, or intermittently, run convergence analysis algorithm 216 to update each of the one or more convergence metrics based on any one or more recorded signals. Processing circuitry 210 may, through convergence analysis algorithm 216, update the convergence status based on the one or more convergence metrics. Based on the one or more convergence metrics determined by convergence analysis algorithm 216 and which of the one or more convergence metrics that were selected, such as by the clinician via external device 104, processing circuitry 210 may continuously or intermittently update the convergence status. If the convergence status has changed (e.g., the convergence metrics have aligned within a tolerance or a range for a period of time) the processing circuitry 210 may have telemetry circuitry 208 send a notification to the clinician that an electrode-tissue interface of IMD 106 has stabilized. The notification may indicate that IMD 106 is ready for the electrical stimulation information 214 to be programmed in or otherwise enabled. Additionally or alternatively, if the convergence status has changed, the processing circuitry 210 may automatically (i.e., autonomously) enable stimulation generation circuitry 202 to stimulate patient 112 based on electrical stimulation information 214 which may have been preset by the clinician or may be a default adopted or modified by the clinician. As such, the convergence analysis algorithm 216 may enable theDocket No.: A0012656W001 / 1123-837WO01 clinician to know when the tissue near electrodes 116, 118 have stabilized and begin stimulation promptly.

[0089] FIG. 3 is a block diagram of the external device 104 of FIG. 1. Although external device 104 may generally be described as a hand-held device, external device 104 may be a larger portable device or a more stationary device. In addition, in other examples, external device 104 may be included as part of an external charging device or include the functionality of an external charging device. In some examples, where external device 104 is a more stationary device, a portion of the more stationary device may have a wand containing the telemetry circuitry that may be moved by a user. As illustrated in FIG. 3, external device 104 may include processing circuitry 310, memory 312, user interface 302, telemetry circuitry 308, and power source 320. Memory 312 may store instructions, including convergence analysis algorithm 316, that, when executed by processing circuitry 310, cause processing circuitry 310 and external device 104 to provide the functionality ascribed to external device 104 throughout this disclosure. Each of these components, or modules, may include electrical circuitry that is configured to perform some, or all, of the functionality described herein. For example, processing circuitry 310 may include processing circuitry configured to perform the processes discussed with respect to processing circuitry 310. Although FIG. 3 is described with respect to IMD 106, and associated components and target tissue structures, of FIG. 1 A, the examples described with respect to FIG. 3 are generally applicable to a variety IMDs and their associated components and target tissue structures (such as IMD 124 of system 100B of FIG. IB or IMD 130 of system 100C of FIG. 1C), application of such techniques to IMD 106 and, more particularly, implantable electrical stimulators (e.g., neurostimulators for deep brain stimulation) will be described for purposes of illustration.

[0090] In general, external device 104 includes any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the techniques attributed to external device 104, and processing circuitry 310, user interface 302, and telemetry circuitry 208 of IMD 106. In various examples, external device 104 may include one or more processors, which may include fixed function processing circuitry and / or programmable processing circuitry, as formed by, for example, one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations thereof. External device 104 also, in various examples, may include memory 312, 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 310 and telemetryDocket No.: A0012656W001 / 1123-837WO01 circuitry 308 are described as separate modules, in some examples, processing circuitry 310 and telemetry circuitry 308 may be functionally integrated. In some examples, processing circuitry 310 and telemetry circuitry 308 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units. While telemetry circuitry 308 is described as being arranged within external device 104, in some examples, aspects of telemetry circuitry 308 (e.g., configuring IMD 106 to advertise at an advertising interval or initiating a communication session) may be performed by telemetry circuitry 308 external to external device 104 (e.g., in an intermediate device).

[0091] Memory 312 (e.g., a storage device) may store instructions that, when executed by processing circuitry 310, cause processing circuitry 310 and external device 104 to provide the functionality ascribed to external device 104 throughout this disclosure. For example, memory 312 may include instructions that cause processing circuitry 310 to obtain a parameter set from memory or receive a user input and send a corresponding command to IMD 106, or instructions for any other functionality. In addition, memory 312 may include a plurality of programs, where each program includes a parameter set that defines stimulation therapy. Memory 312 may additionally or alternatively include convergence analysis algorithm 316 that may enable external device 104 to analyze data received from IMD 106 for the convergence status of different convergence factors as described throughout this disclosure.

[0092] User interface 302 may include a button or keypad, lights, a speaker and / or microphone 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 may be a touch screen. User interface 302 may be configured to display any information related to the delivery of stimulation therapy, identified patient behaviors, sensed patient parameter values, patient behavior criteria, connection metrics or any other such information. User interface 302 may be configured to display any information related to the convergence metric as determined by convergence analysis algorithm 316 and as described throughout this disclosure. User interface 302 may be configured to display feedback indicative of the convergence metric. In some examples, the feedback indicative of the convergence metric may be icons and / or notifications, wherein the color, shape, and / or text of the icon and / or notification communicates the convergence metric. In some examples, a dial may indicate a status of the convergence metric. In some examples, the dial may have two or more sections. The two or more sections may include a red section that indicates a low or poor convergence status, a yellow section that indicates a moderate or okay convergence status, and a greenDocket No.: A0012656W001 / 1123-837WO01 section that indicates a high or good convergence status. The red section, the yellow section, and the green section may blend together. The convergence status (or any other indicator of the metric) may be used by the system to prompt any number of adjustments or notifications to review therapy or related data. For example, a clinician may be notified that the metric exceeds a threshold and prompted to review one or more therapy parameters that may be adjustable by the clinician, such as stimulation parameters, closed-loop feedback parameters, etc. In this manner, the metric described herein can be used to monitor for changes or other variables over time and prompt any number of actions or functions.

[0093] User interface 302 may be configured to display feedback including instructions and recommendations to the user based on the convergence metric. User interface 302 may request the user wait longer so that the implant location of patient 112 has more time to heal. User interface 302 may request the user see the clinician so that the implant location of patient 112 may be inspected. User interface 302 may also receive user input. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. In some examples, user interface 302 may receive other inputs, such as patients drawing or writing, finger tapping, or any other inputs that the system may use to collect information regarding patient condition.

[0094] One or more sensors 301 may include one or more accelerometers 340, a light sensor 342, and a microphone 344. For example, one or more accelerometers 340 may be configured to determine information indicating a movement of external device 104. Information may include one or more of an acceleration in an x-direction, acceleration in a y- direction, or an acceleration in a z-direction. The x-direction may be perpendicular to both the y-direction and the z-direction. While the example of FIG. 3 uses accelerometer 340, in some examples external device 104 may additionally, or alternatively, include a gyroscope that may detect the movement and / or generate motion information. Light sensor 342 may be configured to determine light information (e.g., an ambient light level of an environment detected by light sensor 342). Microphone 344 may be configured to determine sound information (e.g., an ambient sound level of an environment detected by microphone 344). For example, microphone 344 may detect speech (e.g., from patient 122 or a caretaker of patient 122).

[0095] Telemetry circuitry 308 may support wireless communication between IMD 106 and external device 104 under the control of processing circuitry 310. Telemetry circuitry 308 may also be configured to communicate with any suitable computing device via wireless communication techniques, or direct communication through a wired connection. In someDocket No.: A0012656W001 / 1123-837WO01 examples, telemetry circuitry 308 provides wireless communication via an RF or proximal inductive medium. In some examples, telemetry circuitry 308 includes an antenna, which may take on a variety of forms, such as an internal or external antenna.

[0096] External device 104 and IMD 106 may communicate via any one or more local wireless communication techniques that facilitate communication including RFC according to the 802.11 or Bluetooth™ specification sets (e.g., Classic Bluetooth™, Bluetooth™ high speed and Bluetooth™ Low Energy (BLE) protocols) or other standard or proprietary telemetry protocols. In this manner, other external devices 104 may be capable of communicating with external device 104 without needing to establish a secure wireless connection. Telemetry circuitry 308 may be configured to communicate via any other known or future protocols. For example, techniques described herein for establishing a connection between IMD 106 and external device 104 may be compliant with any RFC protocol and / or may use any telemetry frequency.

[0097] Telemetry circuitry 308 may receive an advertisement packet from IMD 106, for example, and connect with any suitable device (e.g., IMD 106) using the received advertisement packet. The advertisement packet may include information on how to connect with the advertising device, such as, for example, one or more of: (1) media access control (MAC) addresses for IMD 106 and external device 104; (2) a real time-point in time for the transfer to start; (3) an indication of a transfer frequency; (4) an indication of a hop set; (5) a connection interval; or (6) a connection latency. For example, telemetry circuitry 308 may establish a connection with IMD 106 using a transfer frequency and hop set indicated by an advertisement broadcast (e.g., on a set of advertising channels) by IMD 106. In this example, other devices may connect with telemetry circuitry 308 using the advertisement output by telemetry circuitry 308.

[0098] In some examples, processing circuitry 310 may define the parameters of electrical stimulation therapy, stored in memory 312, for delivering adaptive DBS to patient 112. In one example, processing circuitry 310 of external device 104, via telemetry circuitry 308, issues commands to IMD 106 causing IMD 106 to deliver electrical stimulation therapy via electrodes 116, 118 via leads 114.

[0099] In accordance with the techniques of the disclosure, external device 104 may implement convergence analysis of the signals recorded by IMD 106 that may be received by telemetry circuitry 308 in processing circuitry 310. Telemetry circuitry 308 may be configured to receive signals from IMD 106 as well as other devices in the vicinity of external device 104. Techniques described herein may decrease the time between anDocket No.: A0012656W001 / 1123-837WO01 electrode-tissue interface being ready to receive stimulation and stimulation being delivered via stimulation generation circuitry. Telemetry circuitry 308 may be configured to send a notification to the clinician when the electrode-tissue interface is stabilized, or otherwise converged, and / or telemetry circuitry 308 may instruct processing circuitry 210 of IMD 106 to automatically (i.e., autonomously) begin stimulation when the electrode-tissue interface is stabilized, or otherwise converged. Power source 320 may include a small rechargeable or non-rechargeable battery and / or a power generation circuit to produce the operating power. Power source 320 may additionally or alternatively include a power connection to a power grid.

[0100] FIG. 4 is a flowchart illustrating an example operation of a device configured to determine one or more convergence metrics and provide an alert based on the convergence metric exceeding one or more thresholds. The device of FIG. 4 is discussed with respect to example IMD 106. Although FIG. 4 is described with respect to IMD 106 of FIG. 1 A, the examples described with respect to FIG. 4 are generally applicable to a variety IMDs (such as IMD 124 of system 100B of FIG. IB or IMD 130 of system 100C of FIG. 1C) and other devices or systems may perform similar functions as described herein.

[0101] IMD 106 may be activated by a clinician with preset values (400). IMD 106 may measure electrical signals and may calculate a convergence metric based on the measured electrical signals (405). IMD 106 may compare the convergence metric to a threshold (410). If the convergence metric is less than a threshold (“NO” branch of block 410), IMD 106 continues to measure the electrical signals. If the convergence metric exceeds (e.g., greater than or meets) a threshold (“YES” branch of block 410), IMD 106 may send an alert the clinician and / or update therapy values (415). In some examples, IMD 106 may enable closed-loop stimulation control in response to the convergence metric exceeding the threshold. Enabling closed-loop stimulation control may include processing circuitry 210 activating the automatic adjustment of one or more parameters that define stimulation according to a pre-stored set of instructions. Enabling closed-loop stimulation may also, or alternatively, include generating a notification for transmission to the clinician that closed- loop stimulation can now be programmed. In some examples, IMD 106 may enable the delivery of stimulation therapy in response to the convergence metric exceeding the threshold if such stimulation was not activated previously. In this manner, IMD 106 may take one or more actions in response to the convergence metric exceeding the threshold which indicates that the electrode-tissue interface may be sufficiently stable for proceeding with various types of therapy.Docket No.: A0012656W001 / 1123-837WO01

[0102] Activating IMD 106 with preset values (400) includes the clinician activating IMD 106 and beginning delivering stimulation through electrodes 116 / 118. The preset values may include settings for the stimulation limits, the frequency of measurement, the length of time over which to measure at the selected frequency, whether therapy is active, and any other setting on IMD 106 which could be modified by settings. The clinician may activate IMD 106 and begin delivering stimulation immediately after implantation and prior to the electrode-tissue interface stabilizing. Such activation may occur minutes to hours after electrodes 116 / 118 are implanted. The clinician may solicit feedback from the patient and adjust the delivered stimulation based on the patient feedback. In some examples, the clinician may choose to not activate IMD 106 and may wait until the electrode-tissue interface has stabilized, or any other second time period, before initializing stimulation. Delivering stimulation shortly after implantation provides the benefit that the patient may experience immediate modulation of their symptoms; however, the patient’s perceived stimulation response may change over time as the electrode-tissue interface heals and changes. Additionally, or alternatively, activating IMD 106 enables the clinician to preset which electrodes of electrodes 116 / 118 to measure electrical signals from in 405. The clinician may select which individual convergence metrics to base the convergence metric on as well as select a threshold against which to measure any one or more of the individual convergence metrics. IMD 106 may additionally or alternatively come preset with default settings where the clinician may adopt the default settings wholesale thereby activating IMD 106 with default preset settings. One or more settings selected by the clinician may be stored in memory 212 of IMD 106.

[0103] IMD 106 may measure electrical signals and may calculate one or more convergence metric(s) based on the measured electrical signals (405). Processing circuitry 210 of IMD 106 may control sensing circuitry 204 to measure electrical signals at a preset frequency of one electrical signal data point every 10 minutes. Additionally, or alternatively, IMD 106 may measure at any other frequency that enables detection of trends in the electrical signals overtime. IMD 106 may measure electrical signals at an electrode-tissue interface that maybe representative of nearby electrical signals of nearby tissue. The electrical signals may include impedances, ECAP signals, LFP signals, evoked resonant neural activation signals, or other signals. Various characteristics, or metrics, may be determined from these signals, such as growth curve features, ECAP amplitude or morphology, signal-to-noise ratio, or any other measurements indicative of electrical signals. ECAP morphology may include the shape of the signals, such as one or more peaks, peak widths, latency, etc. The electrode-Docket No.: A0012656W001 / 1123-837WO01 tissue interface may be the region where electrodes 116 / 118 of leads 114 meet the tissue in which electrodes 116 / 118 are implanted. Measuring electrical signals may include processing circuitry 210 temporarily deactivating stimulation generation circuitry 202, or otherwise switching to sensing circuitry 204 and sensing electrical signals nearby electrodes 116 / 118. Additionally or alternatively, sensing circuitry 204 may sense a response to a stimulation delivered by stimulation generation circuitry 202. Sensing circuitry 204 may sense the electrical response as a summation of nearby electrical responses and any changes of the summed nearby electrical responses may be indicative of the healing process of the electrode-tissue interface post-implantation. Processing circuitry 210 of IMD 106 may additionally take into account any other factors which may influence the nearby electrical responses including therapy type, time of day, patient requests, the day of the week, stress of an associated time of day or day of week (e.g., workday stress) or any other factor that could be informative to a status of an electrode-tissue interface. Processing circuitry 210 of IMD 106 may, based on the neural response or any other input, calculate one or more convergence metrics indicative of a present status of the electrode-tissue interface. Although described as occurring primarily on processing circuitry 210 of IMD 106, calculating convergence metrics (405) may occur on external device 104 of FIGS. 1 A-1C, a server at a remote location, or any other processing hardware capable of performing calculations on electrical signals. The one or more convergence metrics may be summed, weighted, or otherwise combined to yield a convergence status.

[0104] The one or more convergence metric(s) may include any one or more of a detection of whether significant outliers are in the electrical signals, a detection of whether the electrical signals are trending upwards or downwards, whether the electrical signals are monotonically non-decreasing or monotonically non-increasing, whether the electrical signals have experienced a baseline shift, whether the electrical signals have alternating averages, whether the electrical signals match a pattern, or any other characteristic in the electrical signals that indicate a current status of a microlesion, a healing of a microlesion, or any other response to a microlesion. As noted above, the one or more convergence metrics may include any other characteristic in the electrical signals that indicate a current status of a microlesion, a healing of a microlesion, or any other response to a microlesion based on the electrical signals. Although microlesion, and the healing thereof, are described as an example, any other phenomenon may create a condition where the system can look for convergence, or trends, in data in order to determine when to make a change to one or more aspects of patient therapy.Docket No.: A0012656W001 / 1123-837WO01

[0105] Detection of significant outliers in the electrical signals may include processing circuitry 210 of IMD 106 calculating an average and a standard deviation of the electrical signals over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then compare each electrical signals based on the following formula:■^outlier i 3<T, (1)

[0106] Wherein xoutUeris variable based on one or more data points of electrical signals and wherein the data point is a significant outlier if the formula is true for that data point, x is the average of the electrical signals over a period of time, such as a day or more, and <JXis the standard deviation of the electrical signals over the period of time. Three standard deviations from the mean was show as an example, in other examples there may be 1.5, 2, 2.5, 3.5, 4 or any other number of standard deviations from the mean as the baseline for whether the electrical signals are significant outliers. Processing circuitry 210 may then determine the number of data points in the period of time for which the formula is true. Processing circuitry 210 may then compare the number of data points for which the formula is true to a threshold. Processing circuitry 210 may indicate, based on the number of data points for which the formula is true, either that the significant outliers convergence metric is true or may return a value for the significant outliers convergence metric based on how many outliers are in that period of time.

[0107] Detection of whether the electrical signals is trending upwards or trending downwards may include processing circuitry 210 of IMD 106 calculating a derivative of the electrical signals over a period of time. A derivative may represent the rate at which a function changes. Processing circuitry 210 of IMD 106 may approximate the derivative by calculating the difference between consecutive data points and dividing by the difference in their corresponding independent variable values for discrete data sets. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then determine if the derivative over the period of time was positive, negative, or had no conclusive slope based on the value of the derivative. Processing circuitry 210 may additionally or alternatively compare the derivative among the past several periods of time to calculate a second derivative of the electrical signals to determine if the derivative of the electrical signals is changing overtime. Processing circuitry 210 may then set the trending convergence metric as true or may a return a specific value for the trendingDocket No.: A0012656W001 / 1123-837WO01 convergence metric based on how positive or negative the slope of the electrical signals are for that period of time.

[0108] Detection of whether the electrical signals is monotonically non-decreasing or monotonically non-increasing may include processing circuitry 210 of IMD 106 calculating a derivative of the electrical signals over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then determine if the derivative over the past period of time was positive, negative, or had no conclusive slope based on the value of the derivative. Processing circuitry 210 may then compare the derivative to one or more other derivatives of the electrical signals for periods of time prior to the current period of time. If the derivative and the one or more other derivatives are all positive, then the electrical signals are monotonically non-decreasing. If the derivative and the one or more other derivatives are all negative, then the electrical signals are monotonically non-increasing. In some examples, if the derivative and fewer than all of the one or more other derivatives are all positive, then the electrical signals may be substantially monotonically non-decreasing. If the derivative and fewer than all the one or more other derivatives are all negative, then the electrical signals may be substantially monotonically non-increasing. Processing circuitry 210 may then set the monotonic convergence metric as true or may a return a specific value for the monotonic convergence metric based on how monotonically non-decreasing or monotonically non-increasing the electrical signals are for that period of time.

[0109] Detection of whether the electrical signals have experienced a baseline shift may include processing circuitry 210 of IMD 106 calculating an average of the electrical signals over a period of time. The period of time may be one day, two days, or any other period of time as set by the healthcare provider. Processing circuitry 210 may then compare the average based on the following formula:

[0110] Wherein xcurrentis the average for the electrical signals for the current period of time, xbaseUneis an average of the baseline electrical signals that may be calculated by processing circuitry 210 in advance or set by a clinician, and xOffsetis a minimum offset from the baseline that may indicate that a baseline shift has occurred and may be set by the clinician or be preset. Processing circuitry 210 may then determine whether the formula is true for the current period of time and if the formula is true for the current period of time, the baseline shift convergence metric may be true or may a return a specific value for theDocket No.: A0012656W001 / 1123-837WO01 baseline shift convergence metric based on how far off the offset the electrical signals is for that period of time.[OHl] Detection of whether the electrical signals have alternating averages may include processing circuitry 210 of IMD 106 calculating an average over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then compare the average for the current period of time to averages of prior periods of time. If the average for the current period of time matches one or more averages for one or more previous periods of time and if the average for a previous period of time matches one or more averages for one or more different previous periods of time, then the electrical signals may have alternating averages. Processing circuitry 210 may indicate, based on the electrical signals having alternating averages, that the alternating averages convergence metric is true or may return a specific value based on how similar the electrical signals is to the alternating averages for that period of time.

[0112] Detection of whether the electrical signals matches one or more patterns may include processing circuitry 210 of IMD 106 comparing one or more characteristics of the electrical signals over a period of time to pre-set patterns. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may compare one or more principal components of the pre-set patterns to one or more principal components of the electrical signals through the process of principal component analysis. In some examples, the principal components may include eigenvectors. Principal Component Analysis (PCA) may be a technique to reduce the dimensionality of data while preserving variability of the data. PCA may include identifying the directions (principal components) along which the data varies the most. Independent component analysis (ICA) may be used in some examples. These directions may be determined by eigenvectors of a covariance matrix of the data. The corresponding eigenvalues may indicate a magnitude of variation (e.g., a variance, a standard deviation) along each of the eigenvectors. PCA may transform the original data into a new set of uncorrelated variables by projecting the data onto the eigenvectors with the largest eigenvalues, thereby simplifying the dataset while retaining its essential patterns.

[0113] In some examples, the pre-set patterns may be indicative of one or more characteristics of interest and the pre-set patterns may be based on electrical signals collected from one or more other patients or participants. In some examples, memory 212 of IMD 106 may store the pre-set patterns. In other examples, telemetry circuitry 208 of IMD 106 may receive pre-set patterns. Processing circuitry 210 may indicate, based on the electrical signalsDocket No.: A0012656W001 / 1123-837WO01 matching one or more pre-set patterns, that the pattern matching convergence metric may be true or a return a specific value for the pattern matching convergence metric based on how similar the electrical signals are to the pre-set pattern for that period of time.

[0114] IMD 106 may compare the one or more convergence metric(s) to a threshold (410) wherein if the one or more convergence metric(s) are less than a threshold, processing circuitry 210 of IMD 106 may continue to analyze electrical signals and if the one or more convergence metric(s) is greater than a threshold IMD 106 may alert the clinician and / or update therapy values (415). Processing circuitry 210 may compare each of the one or more convergence metric(s) that were calculated in (405) to one or more respective thresholds. Processing circuitry 210 may, based on the comparison, determine a convergence status of the electrode-tissue interface. The convergence status may be a culmination of each of the one or more convergence metrics compared to each of their respective one or more thresholds. In some examples, the convergence status may be true if one or more convergence metrics is true and / or greater than their respective thresholds.

[0115] The convergence status may be based on a stability score that may be based on:

[0116] Wherein RTrueis the number of rules that are true, divided by nRthat is the number of rules. Equation 3 may be modified such that a weight is added for each rule such that the stability score that may be based on:

[0117] Wherein Rweight is the weight assigned to each rule. For example, if two or more convergence metric(s) are selected as the rule, each of the two or more convergence metric(s) may be weighted where processing circuitry 210 may sum up the weights of each individual convergence metric that is true, and compare the summed weight to an overall threshold.

[0118] The clinician may pre-set the one or more thresholds. In some examples, the clinician may accept default values for the one or more thresholds. Processing circuitry 210 and / or the clinician may adjust the one or more thresholds based on one or more characteristics of the electrode-tissue interface, the patient, the therapy delivery goals, and / or any other characteristic that may be helpful to determine the threshold at which to alert the clinician.

[0119] Processing circuitry 210 may, in response to the convergence status improving (i.e., one or more convergence metrics being greater than their respective thresholds and / or the summed weight of the convergence metrics being greater than the overall threshold)Docket No.: A0012656W001 / 1123-837WO01 control telemetry circuitry 208 to send an alert to the clinician of the convergence status. The alert sent to the clinician may indicate that the electrode-tissue interface has stabilized and / or that there is a development of interest for which the clinician’s attention is requested. The alert may be received by the clinician through user interface 302 or any other interface that enables the clinician to receive the alert that the electrode-tissue interface has stabilized.

[0120] Processing circuitry 210 may additionally or alternatively, in response to the convergence status improving (i.e., one or more convergence metrics being greater than their respective thresholds and / or the summed weight of the convergence metrics being greater than the overall threshold) update one or more therapy values. The therapy values may be one or more values, such as preset values, which control the stimulation provided to patient 112. In some examples, processing circuitry 210 may adjust the therapy values in a closed loop fashion based on the convergence status to titrate delivery of therapy as the electrodetissue interface changes post-implantation. Stimulation generation circuitry 202 may reference the therapy values to determine a stimulation waveform, a stimulation frequency, a stimulation intensity, a stimulation pulse-width, or any other factor of stimulation that may be adjusted in response to the convergence status. In some examples, processing circuitry 210 may not to adjust the therapy values and instead processing circuitry 210 may enable therapy delivery in response to a change to the convergence status (i.e., therapy may be enabled in response to an improved convergence status.) Processing circuitry 210 may, in response to the convergence status improving enable remote programming and modification of the preset values whereby the clinician could remotely modify one or more of the stimulation settings for IMD 106.

[0121] Generally, the techniques described herein discuss convergence of sensed signals that may indicate that there is stability in the electrode-tissue interface sufficient for therapy, for example. However, the system may also, or alternatively, track one or more metrics to identify divergence of the metric which could indicate an instability that has been created at the electrode-tissue interface. In this manner, in response to detecting this metric falling back below the threshold, or exceeding some different threshold, IMD 106 suspend stimulation therapy or an aspect of therapy (e.g., closed-loop stimulation) and / or alert the clinician of the potential instability that could affect therapy efficacy.

[0122] FIG. 5 is a flowchart illustrating an example operation of a device configured to determine one or more convergence metrics based on local field potentials (or other electrical signals) and provide an alert based on the one or more convergence metrics. The device of FIG. 5 is discussed with respect to IMD 106 for example purposes only. Although FIG. 5 isDocket No.: A0012656W001 / 1123-837WO01 described with respect to IMD 106 of FIG. 1 A, the examples described with respect to FIG. 5 are generally applicable to a variety IMDs (such as IMD 124 of system 100B of FIG. IB or IMD 130 of system 100C of FIG. 1C) and other devices or systems may perform similar functions as described herein.

[0123] IMD 106 may be implanted by the clinician with preset values (500). IMD 106 may measure chronic local field potentials and may calculate a convergence metric based on the chronic local field potentials (505). IMD 106 may compare the convergence metric to a threshold (510). If the convergence metric is less than a threshold (“NO” branch of block 510), IMD 106 continues to measure the chronic local field potentials. If the convergence metric exceeds (e.g., is greater than) a threshold (“YES” branch of block 510), IMD 106 may send an alert the clinician (515).

[0124] Implanting IMD 106 with preset values (500) includes the clinician implanting IMD 106. The preset values may include settings for the stimulation limits, the frequency of measurement, the length of time over which to measure at the selected frequency, whether therapy is active, and any other setting on IMD 106. The clinician may activate IMD 106 to record chronic local field potentials but may choose to forgo beginning delivering stimulation immediately after implantation prior to the electrode-tissue interface stabilizing. Such activation to record chronic local field potentials may occur minutes to hours after electrodes 116 / 118 are implanted. In some examples, the clinician may activate IMD 106, thereby not waiting until the electrode-tissue interface has stabilized before beginning delivering stimulation. Activating IMD 106 enables the clinician to preset which electrodes of electrodes 116 / 118 to measure chronic local field potentials from in 505. The clinician may select which individual convergence metrics to base the convergence status on as well as select a threshold against which to measure any one or more of the individual convergence metrics. IMD 106 may additionally or alternatively come preset with default settings where the clinician may adopt the default settings wholesale thereby activating IMD 106 with default preset settings.

[0125] IMD 106 may measure chronic local field potentials and may calculate one or more convergence metric(s) based on the chronic local field potentials (505). Processing circuitry 210 of IMD 106 may control sensing circuitry 204 to measure chronic local field potentials at a preset frequency of one data point every 10 minutes. Additionally, or alternatively, IMD 106 may measure at any other frequency that enables detection of trends in the chronic local field potentials overtime. IMD 106 may measure chronic local field potentials at an electrode-tissue interface which maybe representative of nearby chronic localDocket No.: A0012656W001 / 1123-837WO01 field potentials of nearby tissue. The electrode-tissue interface may be the region where electrodes 116 / 118 of leads 114 meet the tissue in which electrodes 116 / 118 are implanted. Processing circuitry 210 may temporarily deactivate stimulation generation circuitry 202, or otherwise switch to sensing circuitry 204 and sense chronic local field potentials nearby electrodes 116 / 118 to measure chronic local field potentials. Additionally or alternatively, sensing circuitry 204 may sense a response to a stimulation delivered by stimulation generation circuitry 202. The chronic local field potentials may be a summation of nearby neuronal responses and may be indicative of the healing process of the electrode-tissue interface post-implantation. Processing circuitry 210 of IMD 106 may, based on the neural response, calculate one or more convergence metrics indicative of a current status of the electrode-tissue interface. Although described as occurring primarily on processing circuitry 210 of IMD 106, calculating convergence metrics (505) may occur on external device 104 of FIGS. 1 A-1C, a server at a second location, or any other processing hardware capable of performing calculations on electrical signals. The one or more convergence metrics may be summed, weighted, or otherwise combined to yield a convergence status.

[0126] The one or more convergence metric(s) may include any one or more of a detection of whether significant outliers are in the chronic local field potential, a detection of whether the chronic local field potentials are trending upwards or downwards, whether the chronic local field potentials are monotonically non-decreasing or monotonically nonincreasing, whether the chronic local field potentials have experienced a baseline shift, whether the chronic local field potentials have alternating averages, whether the chronic local field potentials have pattern matching, or any other characteristic in the chronic local field potentials that indicate a current status of a microlesion, a healing of a microlesion, or any other response to a microlesion. As noted above, the one or more convergence metrics may include any other characteristic in the chronic local field potentials that indicate a current status of a microlesion, a healing of a microlesion, or any other response to a microlesion based on the chronic local field potentials.

[0127] Detection of significant outliers in the chronic local field potential may include processing circuitry 210 of IMD 106 calculating an average and a standard deviation of the chronic local field potentials over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then compare each chronic local field potentials based on equation 1.

[0128] Processing circuitry 210 may then determine the number of data points in the period of time for which the formula is true. Processing circuitry 210 may then compare theDocket No.: A0012656W001 / 1123-837WO01 number of data points for which the formula is true to a threshold. Processing circuitry 210 may indicate, based on the number of data points for which the formula is true, either that the significant outliers convergence metric is true or may return a value for the significant outliers convergence metric based on how many outliers are in that period of time.

[0129] Processing circuitry 210 of IMD 106 may calculate a derivative of the chronic local field potentials over a period of time to detect whether the chronic local field potentials are trending upwards or trending downwards. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then determine if the derivative over the period of time was positive, negative, or had no conclusive slope based on the value of the derivative. Processing circuitry 210 may additionally or alternatively compare the derivative among the past several periods of time to calculate a second derivative of the chronic local field potentials to determine if the derivative of the chronic local field potentials is changing overtime. Processing circuitry 210 may then set the trending convergence metric as true or may a return a specific value for the trending convergence metric based on how positive or negative the slope of the chronic local field potentials are for that period of time.

[0130] Detection of whether the chronic local field potentials are monotonically nondecreasing or monotonically non-increasing may include processing circuitry 210 of IMD 106 calculating a derivative of the chronic local field potentials over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then determine if the derivative over the past period of time was positive, negative, or had no conclusive slope based on the value of the derivative.Processing circuitry 210 may then compare the derivative to one or more other derivatives of the chronic local field potentials for periods of time prior to the current period of time. If the derivative and the one or more other derivatives are all positive, then the chronic local field potentials are monotonically non-decreasing. If the derivative and the one or more other derivatives are all negative, then the chronic local field potentials are monotonically nonincreasing. In some examples, if the derivative and fewer than all of the one or more other derivatives are all positive, then the chronic local field potentials may be substantially monotonically non-decreasing. If the derivative and fewer than all the one or more other derivatives are all negative, then the chronic local field potentials may be substantially monotonically non-increasing. Processing circuitry 210 may then set the monotonic convergence metric as true or may a return a specific value for the monotonic convergenceDocket No.: A0012656W001 / 1123-837WO01 metric based on how monotonically non-decreasing or monotonically non-increasing the chronic local field potentials are for that period of time.

[0131] Detection of whether the chronic local field potentials have experienced a baseline shift may include processing circuitry 210 of IMD 106 calculating an average of the chronic local field potentials over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then compare the average based on equation two. Processing circuitry 210 may then determine whether equation two is true for the current period of time and if equation two is true for the current period of time, the baseline shift convergence metric may be true or may a return a specific value for the baseline shift convergence metric based on how far off the offset the chronic local field potentials is for that period of time.

[0132] Detection of whether the chronic local field potentials have alternating averages may include processing circuitry 210 of IMD 106 calculating an average over a period of time. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may then compare the average for the current period of time to averages of prior periods of time. If the average for the current period of time matches one or more averages for one or more previous periods of time and if the average for a previous period of time matches one or more averages for one or more different previous periods of time, then the chronic local field potentials may have alternating averages. Processing circuitry 210 may indicate, based on the chronic local field potentials having alternating averages, that the alternating averages convergence metric is true or may a return a specific value based on how similar the chronic local field potentials is to the alternating averages for that period of time.

[0133] Detection of whether the chronic local field potentials matches one or more patterns may include processing circuitry 210 of IMD 106 comparing one or more characteristics of the chronic local field potentials over a period of time to pre-set patterns. The period of time may be one day, two days, or any other period of time as set by the clinician. Processing circuitry 210 may compare one or more principal components of the pre-set patterns to one or more principal components of the chronic local field potentials. In some examples, the principal components may include eigenvectors. In some examples, the pre-set patterns may be indicative of one or more characteristics of interest and the pre-set patterns may be based on chronic local field potentials collected from one or more other patients or participants. In some examples, memory 212 of IMD 106 may store the pre-set patterns. In other examples, pre-set patterns may be communicated to IMD 106 via telemetryDocket No.: A0012656W001 / 1123-837WO01 circuitry 208. Processing circuitry 210 may indicate, based on the chronic local field potentials matching one or more pre-set patterns, that the pattern matching convergence metric may be true or a return a specific value for the pattern matching convergence metric based on how similar the chronic local field potentials are to the pre-set pattern for that period of time.

[0134] IMD 106 may compare the one or more convergence metric(s) to a threshold (510). If the one or more convergence metric(s) are less than a threshold, IMD 106 may continue to measure the chronic local field potentials. If the one or more convergence metric(s) is greater than (or exceeds) a threshold IMD 106 may alert the clinician (515). In addition, or alternatively, to alerting the clinician, IMD 106 may enable closed-loop stimulation therapy, enable open-loop stimulation, or perform other actions that may cause IMD 106 to function differently now that the metric exceeds the threshold. Processing circuitry 210 may compare each of the one or more convergence metric(s) that were calculated in (505) to one or more respective thresholds. Processing circuitry 210 may, based on the comparison, determine a convergence status of the electrode-tissue interface.Processing circuitry 210 may determine the convergence status based on a culmination of each of the one or more convergence metrics compared to each of their respective one or more thresholds. In some examples, processing circuitry 210 may base the convergence status on one or more convergence metrics and their respective thresholds. Processing circuitry 210 may calculate the convergence status based on any of equations three or four as described above with respect to FIG. 4.

[0135] Memory 212 may store one or more thresholds as pre-set values which the clinician may adopt via user interface 302. The clinician may select or adopt any one or more values for the one or more thresholds where user interface 302 may control processing circuitry 210 to select which pre-set values to use as each one or more thresholds. The clinician may pre-set the one or more thresholds. In some examples, the clinician may accept via user interface 302 default values for the one or more thresholds wherein processing circuitry 310 may communicate to processing circuitry 210 via telemetry circuitry 308 and telemetry circuitry 208 respectively, which thresholds clinician would like to set for each of the one or more convergence metrics, wherein each of the thresholds may be stored in memory 212 and specifically may be stored in convergence analysis algorithm 216.Processing circuitry 210 and / or the clinician may adjust the one or more thresholds based on one or more characteristics of the electrode-tissue interface, the patient, the therapy deliveryDocket No.: A0012656W001 / 1123-837WO01 goals, and / or any other characteristic that may be helpful to determine the threshold at which to alert the clinician.

[0136] In response to one or more convergence metrics being greater than their respective thresholds and / or the summed weight of the convergence metrics being greater than the overall threshold, processing circuitry 210 may control telemetry circuitry 208 to send an alert to the clinician. The alert sent to the clinician may indicate that the electrode-tissue interface has stabilized and / or that there is a development of interest for which the clinician’s attention is requested. The alert may be received by the clinician through user interface 302 or any other interface that enables the clinician to receive the alert that the electrode-tissue interface has stabilized.

[0137] Processing circuitry 210 may additionally or alternatively, in response to the convergence status improving (i.e., one or more convergence metrics being greater than their respective thresholds and / or the summed weight of the convergence metrics being greater than the overall threshold) update one or more therapy values. The therapy values may be one or more values, such as preset values, that control the stimulation provided to patient 112. In some examples, processing circuitry 210 may adjust the therapy values in a closed loop fashion based on the convergence status to titrate delivery of therapy as the electrode-tissue interface changes post-implantation. Memory 212 may store the therapy values wherein processing circuitry 210 may access the therapy values to control parameters of stimulation generation circuitry 202 include a stimulation waveform, a stimulation frequency, a stimulation intensity, a stimulation pulse-width, or any other factor of stimulation that may be adjusted in response to the convergence status. In some examples, processing circuitry 210 may not change the therapy values and instead processing circuitry 210 may enable therapy delivery in response to a change to the convergence status (i.e., therapy may be enabled in response to an improved convergence status.) Processing circuitry 210 may, in response to the convergence status improving enable remote programming and modification of the preset values whereby the clinician could remotely modify one or more of the stimulation settings for IMD 106.

[0138] After the clinician has been alerted and / or the therapy values have been updated, processing circuitry 210 of IMD 106 may return to step (505) to continue collecting data by measuring chronic local field potentials and calculating convergence metrics. In some examples, processing circuitry 210 may return to step 505 after implantation but before therapy initiation to determine whether the patient’s brain still recovering from the surgical stun (i.e., microlesion) effect. Processing circuitry 210 may titrate therapy less in response toDocket No.: A0012656W001 / 1123-837WO01 a temporary brain response that is the result of implantation after returning to step 505 to determine whether the patient’s brain still recovering. In other examples, processing circuitry 210 may return to step 505 after therapy initiation, before selecting sensing thresholds to determine if the patient’s brain reached a “steady state” with the current therapy regimen. Processing circuitry 210 may maximize the potential for LFP thresholds to capture representative dynamic range of chronic brain response after returning to step 505 to determine if the patient’s brain reached a “steady state” enables. Processing circuitry 210 may return to step 505 after programming or medication changes to determine if the patient’s brain exhibits a trend shift in response to the therapy change(s). Processing circuitry 210 may detect shifts in brain response that may require LFP threshold adjustments to maintain optimal signal capture after returning to step 505 after programming or medication changes. In some examples, processing circuitry 210 may return to step 505 whenever deemed appropriate to determine if the response for a given period needs to be interpreted / flagged differently from the surrounding chronic responses. Processing circuitry 210 may enable acute troubleshooting or otherwise detect a temporary “state” change (e.g., patient was sick for a week) with detectable transient pattern by after returning to step 505 whenever deemed appropriate.

[0139] FIGS. 6A-6C are example user interfaces for a spinal cord stimulator that indicates a convergence status of leads of the spinal cord stimulator. FIG. 6A is an example user interface at a first time after implantation of an IMD (e.g., an implantable neural stimulator) configured to provide spinal cord stimulation. FIG. 6B is an example user interface at a second time after implantation of the IMD configured to provide spinal cord stimulation. FIG. 6C is an example user interface at a third time after implantation of the IMD configured to provide spinal cord stimulation. FIGS. 6A-6C are discussed together for clarity.

[0140] Elements of system 100B, such as IMD 124, leads 126, spinal cord 128, and patient 112 may be substantially similar to similarly numbered elements of FIG. IB. User interface 600 may be presented to a user, such as a clinician or a patient, through any user interface device such as user interface 302 of external device 104 as shown in FIG. 3 or any other user interface device that may display one or more icons, text, colors, or any other suitable information to communicate a status any one or more elements of system 100B. User interface indicates to the user one or more data points that the clinician may find useful to determine whether an electrode-tissue interface has stabilized for the patient. Such one or more data points may include time since implant 602, implant status 604, convergence statusDocket No.: A0012656W001 / 1123-837WO01 dial 606, convergence status text update 608, convergence metrics 610, and implant status shading 612.

[0141] User interface 302 may display a time since implant 602 may be a timer that counts how long the device has been implanted and / or active inside patient 112. Processing circuitry 210 may implement be a timer that counts how long the device has been implanted and / or active inside patient 112 which may then be displayed as time since implant 602.Time since implant 602 may give the clinician and / or patient 112 an indicator of what should be expected since the expectations of the device’s electrode-tissue implant varies based on how long the electrodes, and therefore the device, have been implanted for. For example, typically the longer a device has been implanted for the more stable an electrode-tissue interface is because the tissue has gotten used to the electrode and the immune reaction to the implantation has decreased. User interface 302 may display implant status 604 which may be whether implantable medical device, such as implantable medical device 124 of FIG. IB is active, which may include actively delivering therapy. Processing circuitry 210 may report on whether IMD 124 is active and or determine whether IMD 124 is active based on power consumption, based on whether stimulation generation circuitry 202 is active, or any other factors which indicate whether IMD 124 is active. Implant status 604 may be words such as “active,” “inactive,” “not responding,” or any other words. Implant status 604 may be colored shapes, such as a red circle to indicate the device is off or a green circle to indicate the device is on. Implant status 604 may be any other communicative shape, symbol, signs, color, or any other displayable characters which may communicate a current status of IMD 124.

[0142] User interface 302 may display convergence status dial 606 which may indicate, in a dial format, what the convergence status currently is. Processing circuitry 210 may determine the convergence status via convergence analysis algorithm 216 stored in memory 212. In some examples, convergence status dial 606 may include three separate annulus sectors. A first annulus sector of the three separate annulus sectors may be a left annulus sector which may be colored a first color such as red that may indicate that the convergence status is very low and the electrode-tissue interface is still fresh or healing. A second annulus sector of the three separate annulus sectors may a center annulus sector may be colored a second color such as yellow that may indicate that the convergence status is moderate. Such moderate convergence status may be sufficient or the clinician may choose to allow for additional healing of the electrode-tissue interface before altering stimulation. A third annulus sector of the three separate annulus sectors may be a right annulus sector which mayDocket No.: A0012656W001 / 1123-837WO01 be colored a third color such as green that may indicate that the convergence status is good and the electrode-tissue interface has healed and stabilized. In other examples, there are more than three annulus sectors. In other examples, there may be one continuous annulus sector that may vary in color from a first end to a second end. User interface 302 may display convergence status text update 608 which may include a textual representation of the convergence status indicated by convergence status dial 606 and may additionally or alternatively include other information about the convergence status of the electrode-tissue interface. Convergence status text update 608 may provide information to the clinician about the current status of the convergence or the electrode-tissue interface. In some examples, convergence status text update 608 may include text such as “expect changes in therapy performance,” “lead-tissue interface stabilizing, changes may occur,” “lead-tissue interface stabilized,” and any other suitable language to communicate suitable information regarding the lead-tissue interface to the clinician.

[0143] User interface 302 may display convergence metrics 610 which may be indicators of individual convergence metrics which may be individual components of the overall convergence status. The individual convergence metrics of convergence metrics 610 may be represented by an “X” if the convergence metric does not satisfy its individual threshold (e.g., the value is below its threshold) or a checkmark if the convergence metric satisfies its individual threshold (e.g., the value is above its threshold). In some examples, the individual convergence metrics may be represented by colored shapes, or any other marker that communicates whether the convergence metric is satisfied to the user of user interface 600. User interface 302 may display implant status shading 612 which may be a slight shading or coloring applied to IMD 124 that indicates whether the device is operating or not. The shading of FIG. 6A may indicate that the implant is inactive. In some examples, the shading may indicate that the implant is active. The lack of shading of FIG. 6C may indicate that the implant is active. In some examples, the lack of shading may instead indicate that the implant is inactive.

[0144] FIGS. 7A-7C are example user interfaces for a deep brain stimulator that indicates a convergence status of leads of the deep brain stimulator. FIG. 7A is an example user interface at a first time after implantation of an implantable neural stimulator configured to provide deep brain stimulation. FIG. 7B is an example user interface at a second time after implantation of an implantable neural stimulator configured to provide deep brain stimulation. FIG. 7C is an example user interface at a third time after implantation of anDocket No.: A0012656W001 / 1123-837WO01 implantable neural stimulator configured to provide deep brain stimulation. FIGS. 7A-7C are discussed together for clarity.

[0145] Elements of system 100 A, such as external device 104, IMD 106, connector 108, lead extension 110, patient 112, leads 114, electrodes 116 / 118, brain 120, dura matter 122, may be substantially similar to similarly numbered elements of FIG.1 A. User interface 700 may be presented to a user, such as a clinician or a patient, through any user interface device such as user interface 302 of external device 104 as shown in FIG. 3 or any other user interface device that may display one or more icons, text, or colors. User interface indicates to the user one or more data points that the clinician may find useful to determine whether an electrode-tissue interface has stabilized for the patient. User interface 700 may be similar to user interface 600 as noted in FIGS. 6A-6C. User interface 700 may display one or more data points including time since implant 702, implant status 704, convergence status dial 706, convergence status text update 708, convergence metrics 710, and implant status shading 712.

[0146] User interface 302 may display a time since implant 702 may be a timer that counts how long the device has been implanted and / or active inside patient 112. Processing circuitry 210 of IMD 106 may implement be a timer that counts how long the device has been implanted and / or active inside patient 112 which may be displayed as a time since implant 602. Time since implant 602 may give the clinician and / or patient 112 an indicator of what should be expected since the expectations of the device’s electrode-tissue implant varies based on how long the electrodes, and therefore the device, have been implanted for. For example, typically the longer a device has been implanted for the more stable an electrodetissue interface is because the tissue has gotten used to the electrode and the immune reaction to the implantation has decreased. User interface 302 may display implant status 604 which may be whether implantable medical device, such as implantable medical device 106 of FIG. 1A is active, which may include actively delivering therapy. Processing circuitry 210 may report on whether IMD 106 is active and or determine whether IMD 106 is active based on power consumption, based on whether stimulation generation circuitry 202 is active, or any other factors which indicate whether IMD 106 is active. Implant status 604 may be words such as “active,” “inactive,” “not responding,” or any other words. Implant status 604 may be colored shapes, such as a red circle to indicate the device is off or a green circle to indicate the device is on. Implant status 604 may be any other communicative shape, symbol, signs, color, or any other displayable characters which may communicate a current status of IMD 106.Docket No.: A0012656W001 / 1123-837WO01

[0147] User interface 302 may display convergence status dial 706 which may indicate, in a dial format, what the convergence status currently is. Processing circuitry 210 may determine the convergence status via convergence analysis algorithm 216 stored in memory 212. In some examples, convergence status dial 706 may include three separate annulus sectors. A first annulus sector of the three separate annulus sectors may be a left annulus sector which may be colored a first color such as red that may indicate that the convergence status is very low and the electrode-tissue interface is still fresh or healing. A second annulus sector of the three separate annulus sectors may a center annulus sector may be colored a second color such as yellow that may indicate that the convergence status is moderate. Such moderate convergence status may be sufficient or the clinician may choose to allow for additional healing of the electrode-tissue interface before altering stimulation. A third annulus sector of the three separate annulus sectors may be a right annulus sector which may be colored a third color such as green that may indicate that the convergence status is good and the electrode-tissue interface has healed and stabilized. In other examples, there are more than three annulus sectors. In other examples, there may be one continuous annulus sector that may vary in color from a first end to a second end. User interface 302 may display convergence status text update 708 which may include a textual representation of the convergence status indicated by convergence status dial 706 and may additionally or alternatively include other information about the convergence status of the electrode-tissue interface. Convergence status text update 708 may provide information to the clinician about the current status of the convergence or the electrode-tissue interface. In some examples, convergence status text update 708 may include text such as “expect changes in therapy performance,” “lead-tissue interface stabilizing, changes may occur,” “lead-tissue interface stabilized,” and any other suitable language to communicate suitable information regarding the lead-tissue interface to the clinician.

[0148] User interface 302 may display convergence metrics 710 which may be indicators of individual convergence metrics which may be individual components of the overall convergence status. The individual convergence metrics of convergence metrics 710 may be represented by an “X” if the convergence metric does not satisfy its individual threshold (e.g., the value is below its threshold) or a checkmark if the convergence metric satisfies its individual threshold (e.g., the value is above its threshold). In some examples, the individual convergence metrics may be represented by colored shapes, or any other marker that communicates whether the convergence metric is satisfied to the user of user interface 700. User interface 302 may display implant status shading 712 which may be a slight shading orDocket No.: A0012656W001 / 1123-837WO01 coloring applied to IMD 124 that indicates whether the device is operating or not. The shading of FIG. 7A may indicate that the implant is inactive. In some examples, the shading may indicate that the implant is active. The lack of shading of FIG. 7C may indicate that the implant is active. In some examples, the lack of shading may instead indicate that the implant is inactive.

[0149] FIG. 8 A is an example of local field potential data for a post-surgical microlesion effect that trends upwards. Graph 800 is chronic local field potential readings recorded by electrodes 116 / 118 of a response to implantation of leads 114 inserted into brain 120 of patient 112. Graph 800 includes left axis 802 of the voltage of the LFP response recorded in microvolts, bottom axis 804 of the date the data was recorded on (or a relative time, such as the number of days from implant), individual data points 806, averaged data points 808, and baseline average 810. Averaged data points 808 may be an average of individual data points 806 for a window of interest. The window of interest may be a day (i.e., 24 hours). Baseline average 810 may be an average of individual data points 806 for a day or more at an initialization of a recording. The dashed lines above baseline average 810 may be an upper limit for the baseline and the dashed lines below baseline average 810 may be a lower limit for the baseline. The upper and lower limits for baseline average 810 may correspond to one or more standard deviations from the baseline average, a variance, user selected limits, or any other indication of deviation from the average.

[0150] The chronic local field potential readings, such as individual data points 806 and averaged data points 808 continuously trend upwards, have a shift above baseline (e.g., exceeding the upper limit of baseline average 810), and may have alternating averages. The trend upwards is visible through the increasing values of both individual data points 806 and averaged data points 808 over time. The shift above baseline is visible as both individual data points 806 and averaged data points 808 are above baseline 810. Averaged data points 808 are not monotonically non-decreasing, but may be substantially monotonically nondecreasing because the values continue to increase overtime with only shallow dips below the previous highs. Considering three convergence metrics here, the convergence status is low and therefore the electrode-tissue interface is likely not stabilized.

[0151] FIG. 8B is an example of local field potential data for a post-surgical microlesion effect that trends upwards away from a convergence level. The example of FIG. 8B may illustrate similar phenomenon as FIG. 8A. Graph 820 is chronic local field potential readings recorded by electrodes 116 / 118 of a response to implantation of leads 114 inserted into brain 120 of patient 112. The patient of the data for FIG. 8A may be different than patient fromDocket No.: A0012656W001 / 1123-837WO01 which the data for FIG. 8B was recorded. The data for FIG. 8B may be recorded from the left hemisphere of the brain, inserted into the golbus palludis internus for the treatment of Parkinson’s disease. Graph 820 includes left axis 802 of the voltage of the LFP response recorded in microvolts, bottom axis 804 of the date the data was recorded on, individual data points 806, averaged data points 808, and baseline average 810. Averaged data points 808 may be an average of individual data points 806 for a window of interest. The window of interest may be a day (i.e., 24 hours). Baseline average 810 may be an average of individual data points 806 for a day or more at an initialization of a recording. The dashed lines above baseline average 810 may be an upper limit for the baseline and the dashed lines below baseline average 810 may be a lower limit for the baseline.

[0152] The chronic local field potential readings, such as individual data points 806 and averaged data points 808 continuously trend upwards, have a shift above baseline, and are substantially monotonically non-decreasing. The trend upwards is visible through the increasing values of both individual data points 806 and averaged data points 808 over time. The shift above baseline is visible as both individual data points 806 and averaged data points 808 indicated by the multiple “X” points are above baseline 810 and the upper limit.Averaged data points 808 are not strictly monotonically non-decreasing but are substantially monotonically non-decreasing as the values have alternating averages towards the end with the saw-tooth pattern of the averaged data points 808. Considering three convergence metrics here, the convergence status is low and therefore the electrode-tissue interface is likely not stabilized.

[0153] FIG. 8C is an example of local field potential data for a post-surgical microlesion effect that trends towards a convergence level. Graph 840 is chronic local field potential readings recorded by electrodes 116 / 118 of a response to implantation of leads 114 inserted into brain 120 of patient 112. The patient of the data for FIGS. 8A and 8B may be different than patient from which the data for FIG. 8C was recorded. Th data may be recorded in the right hemisphere of the brain, inserted into the subthalamic nucleus (STN) for the treatment of Parkinson’s disease. Graph 840 includes left axis 802 of the voltage of the LFP response recorded in microvolts, bottom axis 804 of the date the data was recorded on, individual data points 806, averaged data points 808, and baseline average 810. Averaged data points 808 may be an average of individual data points 806 for a window of interest. The window of interest may be a day (i.e., 24 hours). Baseline average 810 may be an average of individual data points 806 for a day or more at an initialization of a recording. The dashed lines above baseline average 810 may be an upper limit for the baseline and the dashed lines belowDocket No.: A0012656W001 / 1123-837WO01 baseline average 810 may be a lower limit for the baseline. Averaged data points 808 above the upper limit or below the lower limit are indicated by an “X”.

[0154] The chronic local field potential readings, such as individual data points 806 and averaged data points 808 do not continuously trend upwards, do have a temporary shift below and then above the limits of baseline average 810, and are not monotonically non-decreasing. The lack of a trend upwards is visible through the values of both individual data points 806 and averaged data points 808 being relatively stable over time. The temporary movement of data points 806 above baseline is visible as both individual data points 806 and averaged data points 808 are above baseline average 810 and the upper limit after day 8. The average data points 808 (i.e., daily averages) stay above baseline average 810 for the remainder of the tested period but generally below the upper limit. Although the baseline may slightly shift higher after day 8, the averaged data points 808 generally remain below the upper limit. Averaged data points 808 are not monotonically non-decreasing. Considering these convergence metrics for a period of time, the convergence status is high for the data of FIG. 8C and therefore the electrode-tissue interface is likely stabilized during this period of time.

[0155] The following examples are a non-limiting list of examples in accordance with one or more techniques of this disclosure.

[0156] Example 1 : A system comprising: processing circuitry configured to: receive information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determine, based on the electrical signals, a metric; compare the metric to a threshold; determine that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enable closed-loop control of electrical stimulation therapy.

[0157] Example 2. The system of example 1, wherein the electrical signals comprise at least one of: an impedance, evoked compound action potential (ECAP) signals, local field potentials (LFPs), or cardiac signals.

[0158] Example 3. The system of any of examples 1 and 2, wherein the metric comprises a trend metric.

[0159] Example 4. The system of any of examples 1 through 3, wherein the metric comprises a convergence metric.

[0160] Example 5. The system of any of examples 1 through 4, wherein the convergence metric is based on:Docket No.: A0012656W001 / 1123-837WO01 wherein RTrueis whether a rule is above a respective threshold, wRis a weight of that rule, and nRis a number of rules being used for the convergence metric.

[0161] Example 6. The system of any of examples 1 through 5, wherein the convergence metric is based on a trend metric and an outlier metric, wherein the trend metric is based on a comparison of the electrical signals to a 24 hour average of the electrical signals, and wherein the outlier metric is based on: x > x + 3<J%wherein x is the current electrical signal, x is the 24 hour average of the electrical signals, and <JXis a standard deviation of the electrical signals.

[0162] Example 7. The system of any of examples 1 through 6, wherein the convergence metric comprises a weighted fraction of two or more metrics.

[0163] Example 8. The system of any of examples 1 through 7, further comprising communication circuitry configured to: communicate the metric to a user interface of an external device; and receive updates to the stimulation parameters and the threshold from the external device.

[0164] Example 9. The system of any of examples 1 through 8, wherein providing the alert comprises communicating the alert to the user interface of the external device, wherein the external device is clinical programmer.

[0165] Example 10. The system of any of examples 1 through 9, wherein adjusting the stimulation parameters comprises a healthcare provider remotely updating the stimulation parameters.

[0166] Example 11. The system of any of examples 1 through 10, wherein the metric comprises a transience metric based on a quantity and duration of transient outliers.

[0167] Example 12. The system of any of examples 1 through 11, further comprising memory circuitry configured to store the electrical signals and the metric at one or more time points.

[0168] Example 13. The system of any of examples 1 through 12, wherein the processing circuitry is further configured to compare the electrical signals and the metric to electrical signals and metric stored in the memory circuitry.

[0169] Example 14. The system of any of examples 1 through 13, wherein the electrical signals of the calculating the metric comprises a window of interest, the window of interest defining a time period of electrical signals.Docket No.: A0012656W001 / 1123-837WO01

[0170] Example 15. The system of any of examples 1 through 14, wherein: the electrical signals are local field potential signals, the stimulation is a deep brain stimulation, the metric is a trend metric, and the providing the alert comprises an indicating to a healthcare provider that a microlesion effect has stabilized or is below a microlesion threshold based on safety metrics.

[0171] Example 16. The system of any of examples 1 through 15, wherein: the electrical signals are ECAP morphology signals, the stimulation is a spinal cord stimulation, the metric is a convergence metric, and the providing the alert comprises an indicating to a healthcare provider that a neural interface has stabilized or is below a healing threshold based on safety metrics.

[0172] Example 17. The system of any of examples 1 through 16, wherein the processing circuitry is configured to, responsive to the metric exceeding the threshold, at least one of adjust one or more stimulation parameters that define stimulation therapy or control transmission of an alert indicating that the metric exceeded the threshold.

[0173] Example 18. The system of any of examples 1 through 17, further comprising an implantable medical device comprising: sensing circuitry configured to sense the electrical signals; and stimulation circuitry configured to deliver the electrical stimulation therapy;

[0174] Example 19. A method comprising: receiving, by processing circuitry, information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determining, based on the electrical signals, a metric; comparing the metric to a threshold; determining that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enabling closed-loop control of electrical stimulation therapy.

[0175] Example 20. The method of example 19, wherein the metric comprises a convergence metric.

[0176] Example 21. The method of any of examples 17 and 18, further comprising: communicating, via communication circuitry, the metric to a user interface of an external device; and receiving, via the communication circuitry, updates to the stimulation parameters and the threshold from the external device.

[0177] Example 22. The method of any of examples 19 through 21, wherein: the electrical signals are local field potential signals, the metric is a trend metric, and the providing the alert comprises an indicating to a healthcare provider that a microlesion effect has stabilized or is below a lesion threshold based on safety metrics.Docket No.: A0012656W001 / 1123-837WO01

[0178] Example 23. The method of any of examples 19 through 21, wherein: the electrical signals are ECAP morphology signals, the metric is a trend metric, and the providing the alert comprises an indicating to a healthcare provider that a healing has stabilized or is below a healing threshold based on safety metrics.

[0179] Example 24. A non-transitory computer-readable storage medium comprising instructions that, when executed by processing circuitry, cause the processing circuitry to: receive information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determine, based on the electrical signals, a metric; compare the metric to a threshold; determine that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enable closed-loop control of electrical stimulation therapy.

[0180] 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 described techniques may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “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. A control unit comprising hardware may also perform one or more of the techniques of this disclosure.

[0181] Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules or components may be implemented together or separately as discrete but interoperable logic devices. 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 or software 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.

[0182] The techniques described in this disclosure may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable storage medium may cause a programmable processor, or other processor, to perform the method, e.g., when theDocket No.: A0012656W001 / 1123-837WO01 instructions are executed. Computer readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.

[0183] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

Docket No.: A0012656W001 / 1123-837WO01WHAT IS CLAIMED IS:

1. A system comprising: processing circuitry configured to: receive information representative of electrical signals sensed via one or more implanted leads, wherein each lead of the one or more implanted leads carry one or more electrodes; determine, based on the electrical signals, a metric; compare the metric to a threshold; determine that the metric exceeds the threshold; and responsive to determining that the metric exceeds the threshold, enable closed- loop control of electrical stimulation therapy.

2. The system of claim 1, wherein the electrical signals comprise at least one of: an impedance, evoked compound action potential (ECAP) signals, local field potentials (LFPs), or cardiac signals.

3. The system of any of claims 1 and 2, wherein the metric comprises a trend metric.

4. The system of any of claims 1 through 3, wherein the metric comprises a convergence metric.

5. The system of any of claims 1 through 4, wherein the convergence metric is based on:wherein RTrueis whether a rule is above a respective threshold, wRis a weight of that rule, and nRis a number of rules being used for the convergence metric.Docket No.: A0012656W001 / 1123-837WO016. The system of any of claims 1 through 5, wherein the convergence metric is based on a trend metric and an outlier metric, wherein the trend metric is based on a comparison of the electrical signals to a 24 hour average of the electrical signals, and wherein the outlier metric is based on: x > x + 3<J%wherein x is the current electrical signal, x is the 24 hour average of the electrical signals, and <JXis a standard deviation of the electrical signals.

7. The system of any of claims 1 through 6, wherein the convergence metric comprises a weighted fraction of two or more metrics.

8. The system of any of claims 1 through 7, further comprising communication circuitry configured to: communicate the metric to a user interface of an external device; and receive updates to the stimulation parameters and the threshold from the external device.

9. The system of any of claims 1 through 8, wherein providing the alert comprises communicating the alert to the user interface of the external device, wherein the external device is clinical programmer.

10. The system of any of claims 1 through 9, wherein adjusting the stimulation parameters comprises a healthcare provider remotely updating the stimulation parameters.

11. The system of any of claims 1 through 10, wherein the metric comprises a transience metric based on a quantity and duration of transient outliers.

12. The system of any of claims 1 through 11, further comprising memory circuitry configured to store the electrical signals and the metric at one or more time points.Docket No.: A0012656W001 / 1123-837WO0113. The system of any of claims 1 through 12, wherein: the electrical signals are local field potential signals, the stimulation is a deep brain stimulation, the metric is a trend metric, and the providing the alert comprises an indicating to a healthcare provider that a microlesion effect has stabilized or is below a microlesion threshold based on safety metrics.

14. The system of any of claims 1 through 12, wherein: the electrical signals are ECAP morphology signals, the stimulation is a spinal cord stimulation, the metric is a convergence metric, and the providing the alert comprises an indicating to a healthcare provider that a neural interface has stabilized or is below a healing threshold based on safety metrics.

15. The system of any of claims 1 through 14, further comprising an implantable medical device comprising: sensing circuitry configured to sense the electrical signals; and stimulation circuitry configured to deliver the electrical stimulation therapy.

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