Patent Description:
Medical devices may be external or implanted and may be used to deliver electrical stimulation therapy to patients via various tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. A medical device may deliver electrical stimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Stimulation proximate the spinal cord, proximate the sacral nerve, within the brain, and proximate peripheral nerves are often referred to as spinal cord stimulation (SCS), sacral neuromodulation (SNM), deep brain stimulation (DBS), tibial stimulation and peripheral nerve stimulation (PNS).

Electrical stimulation may be delivered to a patient by the medical device in a train of electrical pulses, and parameters of the electrical pulses may include a frequency, an amplitude, a pulse width, and a pulse shape. An evoked compound action potential (ECAP) is synchronous firing of a population of neurons which occurs in response to the application of a stimulus including, in some cases, an electrical stimulus by a medical device. The ECAP may be detectable as being a separate event from the stimulus itself, and the ECAP may reveal characteristics of the effect of the stimulus on the nerve fibers. Documents <CIT> and <CIT> relate to electrical stimulation and parameter adjustments.

In general, the disclosure describes devices, systems, and techniques for adjusting cycling of electrical stimulation therapy delivered by a medical device. In this manner, the medical device may balance the trade-off between clinical efficacy of electrical stimulation therapy to relieve patient symptoms and the amount of electrical energy consumed to deliver the electrical stimulation therapy. For example, a system may iteratively adjust the duration of delivered therapy and verify the patient's symptoms.

In one example, this disclosure describes method comprising: causing, by processing circuitry, electrical stimulation circuitry of an implantable medical device (IMD) to output electrical stimulation therapy to a patient via electrodes implanted near a target nerve of the patient, wherein the electrical stimulation therapy is defined by parameters, the parameters comprising ON-time and OFF-time; incrementing, by the processing circuitry, the OFF-time by a first duration; receiving, by the processing circuitry, input via a user interface operatively coupled to the processing circuitry, the input describing the state of symptoms of the patient, wherein the electrical stimulation therapy is configured to relieve the symptoms; responsive to receiving input that the symptoms of the patient have not returned incrementing, by the processing circuitry, the OFF-time again by the first duration; responsive to receiving input that the symptoms of the patent have returned: decreasing, by the processing circuitry, the OFF-time by a second duration; and receiving, by the processing circuitry, input via the user interface describing the state of symptoms of the patient. After decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have returned decreasing, by the processing circuitry, the OFF-time again by the second duration.

In another example, this disclosure describes a system comprising: an electrical lead comprising one or more electrodes in contact with tissue of a patient; a user interface configured to receive input from a user; an implantable medical device comprising: an electrical connector configured to connect to the electrical lead; electrical stimulation circuitry configured to output electrical stimulation therapy to a patient via the one or more electrodes, wherein the electrical stimulation therapy is configured to relieve symptoms of the patient. The system further includes processing circuitry configured to: cause the electrical stimulation circuitry to output electrical stimulation therapy to a patient wherein the electrical stimulation therapy is defined by parameters, the parameters comprising ON-time and OFF-time; increment the OFF-time by a first duration; receive input via the user interface, the input describing the state of symptoms of the patient; responsive to receiving input that the symptoms of the patient have not returned increment the OFF-time again by the first duration; responsive to receiving input that the symptoms of the patent have returned: decrease the OFF-time by a second duration; and receive input via the user interface describing the state of symptoms of the patient; after decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have returned decrease the OFF-time again by the second duration.

In another example, this disclosure describes a non-transitory computer-readable storage medium comprising instructions that, when executed, cause one or more processors of a computing device to: cause electrical stimulation circuitry of an implantable medical device to output electrical stimulation therapy to a patient wherein: the electrical stimulation therapy is defined by parameters, the parameters comprising ON-time and OFF-time, and wherein the electrical stimulation therapy is configured to relieve symptoms of the patient; increment the OFF-time by a first duration; receive input via a user interface, the input describing the state of symptoms of the patient; responsive to receiving input that the symptoms of the patient have not returned increment the OFF-time again by the first duration; responsive to receiving input that the symptoms of the patent have returned: decrease the OFF-time by a second duration; and receive input via the user interface describing the state of symptoms of the patient; after decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have returned decrease the OFF-time again by the second duration.

The devices, systems, and techniques of this disclosure relate to a medical device setup procedure that enables a system to semi-automatically find a stimulation ON time and stimulation OFF time, or adjust those times, to determine a medical device programmed configuration that may reduce the amount of energy consumed while maintaining efficacious therapy for a particular patient. Increasing the duration of the time OFF and decreasing the duration of the time ON may use less battery capacity, but may result in patient discomfort if stimulation is delivered for an inadequate amount of time that enables symptoms to return.

Using an external computing device, e.g., a medical device programmer, the healthcare provider (HCP) or the patient, may start the setup procedure via a user interface. Processing circuitry of the external computing device may start by automatically changing the configuration of the implantable medical device (IMD) by programming a first ON interval duration and a first OFF interval duration. The algorithm may be semi-automatic in examples where the system will pause while waiting for a response from the patient. In other examples, processing circuitry of the IMD may execute the steps of the algorithm, rather than receiving updated programming commands from the external computing device.

The processing circuitry may re-program the IMD to increase the time OFF by a preset amount, pausing for each trial, until the patient reports that the symptom breakthrough, e.g., the symptoms, such as pain, become noticeable. The processing circuitry may then reduce the time OFF to the pain-free setting (or at least pain reduced, depending on the patient). Then the processing circuitry may perform similar trials by reducing the electrical stimulation time ON in specified increments, pausing for each trial, until the patient reports symptom breakthrough, e.g., feeling more pain than if the electrical stimulation was reducing the pain. The processing circuitry may then increase the time ON to the pain-free or pain-reduced setting. This disclosure will focus on electrical stimulation therapy to relieve pain, to simplify the description. However, pain reduction is just one example of a patient symptom. The techniques of this disclosure apply equally to other symptoms, such as incontinence, epilepsy symptoms, Parkinson's tremors, gait issues. In the example of a cardiac device, symptoms may include bradycardia, reduced or increased blood flow as measured by an echocardiogram, and so on.

The techniques of this disclosure may apply to any portable device, e.g., a device that depends on a battery or other electrical energy storage unit. For example, wearable medical devices may be worn externally, such as on a belt loop, straps or adhesive, or may be implanted in a patient. Wearable devices may include a battery to power the device, which may need to be periodically charged or replaced. In the example of an implanted device, the patient requires surgery to remove and replace the device with a new device and fresh battery. Rechargeable devices may be recharged with a power transfer device including a coil and electronics to monitor and control the recharging, as well as communicate with the medical device. For medical devices configured to deliver therapy to reduce pain and other symptoms, the medical device may deliver electrical stimulation signals, such as a series of electrical current pulses, through electrodes placed on leads implanted near nerves, such as near the spinal cord. Each patient may require a different magnitude, frequency, and other stimulation parameters based on the patient physiology, patient sensitivity as well as based on the type of device, electrodes, and where the electrodes sit relative to the target tissue, e.g., a target nerve.

In some examples, a patient, or caregiver, may run the setup procedure to set or adjust the ON and OFF times as many times as desired over the life of the medical device. Also, in some examples, the setup procedure may provide separate time durations as needed during the day. For example, the ON and OFF times may be different for daytime activity hours when compared to night sleeping hours. In some examples the OFF time may be set to a longer duration during sleep to provide greater energy savings. In some examples, the switch between the separate setting durations may be triggered by the patient, by an internal clock of the medical device, by an accelerometer to determine active times versus sleep times, and so on.

<FIG> is a conceptual diagram illustrating an example system <NUM> that includes an IMD <NUM> configured to deliver spinal cord stimulation (SCS) therapy and an external computing device <NUM>, 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, 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.

As shown in <FIG>, system <NUM> includes an IMD <NUM>, leads 130A and 130B, and external computing device <NUM> shown in conjunction with a patient <NUM>, who is ordinarily a human patient. In the example of <FIG>, IMD <NUM> is an implantable electrical stimulator that is configured to generate and deliver electrical stimulation therapy to patient <NUM> via one or more electrodes of electrodes of leads 130A and/or 130B (collectively, "leads <NUM>"), e.g., for relief of chronic pain or other symptoms. In other examples, IMD <NUM> may be coupled to a single lead carrying multiple electrodes or more than two leads each carrying multiple electrodes. IMD <NUM> may include an electrical connector configured to connect to the electrical leads, e.g., in the header of IMD <NUM>. In some examples, the stimulation signals, or pulses, may be configured to elicit detectable ECAP signals that IMD <NUM> may use to determine the posture state occupied by patient <NUM> and/or determine how to adjust one or more parameters that define stimulation therapy. IMD <NUM> may be a chronic electrical stimulator that remains implanted within patient <NUM> for weeks, months, or even years. In other examples, IMD <NUM> may be a temporary, or trial, stimulator used to screen or evaluate the efficacy of electrical stimulation for chronic therapy. In one example, IMD <NUM> is implanted within patient <NUM>, while in another example, IMD <NUM> is an external device coupled to percutaneously implanted leads. In some examples, IMD <NUM> uses one or more leads, while in other examples, IMD <NUM> is leadless.

This disclosure will focus on a device used for spinal cord stimulation, as shown in the example of <FIG> to simplify the description. However, the techniques of this disclosure may also apply to other devices, including wearable devices, that may be located elsewhere on patient <NUM>. Some examples may include devices located near the head for DBS, near the tibial region, near the heart for cardiac therapy and/or monitoring, and so on.

In other words, although in one example IMD <NUM> takes the form of an SCS device, in other examples, IMD <NUM> 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 used to determine parameters that affect stimulation thresholds (e.g., perception thresholds and detection thresholds) associated any one of the aforementioned IMDs and then use a stimulation threshold to inform the intensity (e.g., stimulation levels) of therapy. For example, changing stimulation parameters such as the number of pulses in a burst, the number of bursts over a duration, the pulse width of a pulse in a burst, the ON-time, the OFF-time, a pattern of pulses over a duration and other parameters may change the intensity as well as the efficacy of the therapy to relieve the symptoms.

IMD <NUM> may be constructed of any polymer, metal, or composite material sufficient to house the components of IMD <NUM> (e.g., components illustrated in <FIG>) within patient <NUM>. In this example, IMD <NUM> may be constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material such as silicone, polyurethane, or a liquid crystal polymer, and surgically implanted at a site in patient <NUM> near the pelvis, abdomen, or buttocks. In other examples, IMD <NUM> may be implanted within other suitable sites within patient <NUM>, which may depend, for example, on the target site within patient <NUM> for the delivery of electrical stimulation therapy. The outer housing of IMD <NUM> may be configured to provide a hermetic seal for components, such as a rechargeable or non-rechargeable power source. In addition, in some examples, the outer housing of IMD <NUM> is selected from a material that facilitates receiving energy to charge the rechargeable power source.

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

The electrodes 132A and 132B of leads <NUM> 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 lead <NUM> will be described for purposes of illustration.

The deployment of electrodes 132A and 132B via leads <NUM> is described for purposes of illustration, but arrays of electrodes may be deployed in different ways. For example, a housing associated with a leadless stimulator may carry arrays of electrodes, e.g., rows and/or columns (or other patterns), to which shifting operations may be applied. Such electrodes may be arranged as surface electrodes, ring electrodes, or protrusions. As a further alternative, electrode arrays may be formed by rows and/or columns of electrodes on one or more paddle leads. In some examples, electrode arrays include electrode segments, which are arranged at respective positions around a periphery of a lead, e.g., arranged in the form of one or more segmented rings around a circumference of a cylindrical lead. In other examples, one or more of leads <NUM> are linear leads having <NUM> ring electrodes along the axial length of the lead. In another example, the electrodes are segmented rings arranged in a linear fashion along the axial length of the lead and at the periphery of the lead.

The stimulation parameter set of a therapy stimulation program that defines the stimulation pulses of electrical stimulation therapy by IMD <NUM> through the electrodes of leads <NUM> may include information identifying which electrodes have been selected for delivery of stimulation according to a stimulation program, the polarities of the selected electrodes, i.e., the electrode combination for the program, 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 <NUM> based on one or more factors or user input.

Although <FIG> is directed to SCS therapy, e.g., used to treat pain, in other examples system <NUM> may be configured to treat any other condition that may benefit from electrical stimulation therapy. For example, system <NUM> may be used to treat tremor, Parkinson's disease, epilepsy, a pelvic floor disorder (e.g., urinary incontinence or other bladder dysfunction, fecal incontinence, pelvic pain, bowel dysfunction, or sexual dysfunction), obesity, gastroparesis, or psychiatric disorders (e.g., depression, mania, obsessive compulsive disorder, anxiety disorders, and the like). In this manner, system <NUM> 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 <NUM>.

In some examples, lead <NUM> includes one or more sensors configured to allow IMD <NUM> to monitor one or more parameters of patient <NUM>, 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 <NUM>.

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

IMD <NUM> is configured to generate and deliver electrical stimulation therapy to a target stimulation site within patient <NUM> via the electrodes of leads <NUM> to patient <NUM> 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 <NUM> according to that program. For example, a therapy stimulation program that controls delivery of stimulation by IMD <NUM> 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 <NUM> according to that program. In some examples, parameters may include sequences of pulses, for example a "burst" of pulses with gradually increasing current magnitudes, or some other sequence. In some examples, IMD <NUM> may deliver therapy for a given duration and stop delivering therapy for a given duration. In other words, parameters of the electrical stimulation therapy may include an ON-time and an OFF-time. In some examples, an ON-time may be a few seconds or minutes and the OFF-time may also be for a few seconds or minutes. The ON-time may be equal to the OFF-time in some examples, while in other examples the ON-time and the OFF-time may be different durations.

The time durations may be patient specific and vary considerably as each patient is slightly different. Some examples of possible cycling patterns may include: one minute ON/one minute OFF, five minutes ON/one minute OFF, one minute ON/<NUM> seconds OFF, and so on.

In other examples, the time durations may be based on a ratio of ON time to OFF time, rather a specific duration. In one example implementation, the programmer may present ratio-based choices and then auto-learn the ratio as the patient changes the initial preset algorithm. In some examples, the setup procedure executing by processing circuitry of system <NUM> (e.g., processing circuitry of IMD <NUM>, external computing device <NUM>, or some combination of each) may then either recommend or present ON/OFF durations that meet that same ratio. For example, as the user is conducting the setup procedure, the system may identify that one of a <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM> ratio, and so on may be working best for the patient. The system may then change its algorithm to utilize those ratio the patient has identified. That is, ff the patient trial is showing that <NUM>:<NUM> ratios are working best for the patient, the processing circuitry of the system may change the preset trial algorithm to ratios such as: <NUM> sec ON/<NUM> sec off, 2sec ON/2OFF, <NUM> ON/<NUM> off and so on. In this manner, the system may learn and suggest new ON/OFF patterns that meet the needs of the patient.

Furthermore, IMD <NUM> may be configured to deliver control stimulation to patient <NUM> via a combination of electrodes of leads <NUM>, alone or in combination with an electrode carried by or defined by an outer housing of IMD <NUM> in order to detect ECAP signals (e.g., control pulses and/or informed pulses). The tissue targeted by the stimulation may be the same or similar tissue targeted by the electrical stimulation therapy, but IMD <NUM> may deliver stimulation pulses for ECAP signal detection via the same, at least some of the same, or different electrodes. Since control stimulation pulses can be delivered in an interleaved manner with informed pulses (e.g., when the pulses configured to contribute to therapy interfere with the detection of ECAP signals or pulse sweeps intended for posture state detection via ECAP signals do not correspond to pulses intended for therapy purposes), a clinician and/or user may select any desired electrode combination for informed pulses. Like the electrical stimulation therapy, the control stimulation may be in the form of electrical stimulation pulses or continuous waveforms. In one example, each control stimulation pulse may include a balanced, bi-phasic square pulse that employs an active recharge phase. However, in other examples, the control stimulation pulses may include a monophasic pulse followed by a passive recharge phase. In other examples, a control pulse may include an imbalanced bi-phasic portion and a passive recharge portion. Although not necessary, a bi-phasic control pulse may include an interphase interval between the positive and negative phase to promote propagation of the nerve impulse in response to the first phase of the bi-phasic pulse. The control stimulation may be delivered without interrupting the delivery of the electrical stimulation informed pulses, such as during the window between consecutive informed pulses. The control pulses may elicit an ECAP signal from the tissue, and IMD <NUM> may sense the ECAP signal via two or more electrodes on leads <NUM>. In cases where the control stimulation pulses are applied to spinal cord <NUM>, the signal may be sensed by IMD <NUM> from spinal cord <NUM>.

IMD <NUM> can deliver control stimulation to a target stimulation site within patient <NUM> via the electrodes of leads <NUM> according to one or more ECAP test stimulation programs. The one or more ECAP test stimulation programs may be stored in a storage device of IMD <NUM>. Each ECAP test program of the one or more ECAP test stimulation programs include values for one or more parameters that define an aspect of the control stimulation delivered by IMD <NUM> according to that program, such as current or voltage amplitude, pulse width, pulse frequency, electrode combination, ON-time, OFF-time and, in some examples, timing based on informed pulses to be delivered to patient <NUM>. In some examples, the ECAP test stimulation program may also define the number of pules and parameter values for each pulse of multiple pulses within a pulse sweep configured to obtain a plurality of ECAP signals for respective pulses in order to obtain the growth curve that IMD <NUM> may use to determine the current posture state of the patient. In some examples, IMD <NUM> delivers control stimulation to patient <NUM> according to multiple ECAP test stimulation programs.

A user, such as a clinician or patient <NUM>, may interact with a user interface of an external computing device <NUM> to program IMD <NUM>. In some examples, external computing device <NUM> may also be referred to as a programmer. Programming of IMD <NUM> may refer generally to the generation and transfer of commands, programs, or other information to control the operation of IMD <NUM>. In this manner, IMD <NUM> may receive the transferred commands and programs from external computing device <NUM> to control stimulation, such as electrical stimulation therapy (e.g., informed pulses) and/or control stimulation (e.g., control pulses). For example, external computing device <NUM> may transmit therapy stimulation programs, ECAP test stimulation programs, stimulation parameter adjustments, therapy stimulation program selections, ECAP test program selections, user input, or other information to control the operation of IMD <NUM>, e.g., by wireless telemetry or wired connection.

In some cases, external computing device <NUM> may be characterized as a physician or clinician programmer if it is primarily intended for use by a physician or clinician. In other cases, external computing device <NUM> may be characterized as a patient programmer if it is primarily intended for use by a patient. A patient programmer may be generally accessible to patient <NUM> and, in many cases, may be a portable device that may accompany patient <NUM> throughout the patient's daily routine. For example, a patient programmer may receive input from patient <NUM> 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 a clinician for use by IMD <NUM>, whereas a patient programmer may support adjustment and selection of such programs by a patient during ordinary use. In other examples, external computing device <NUM> may include, or be part of, an external charging device that recharges a power source of IMD <NUM>. In this manner, a user may program and charge IMD <NUM> using one device, or multiple devices.

As described herein, information may be transmitted between external computing device <NUM> and IMD <NUM>. Therefore, IMD <NUM> and external computing device <NUM> 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 computing device <NUM> includes a communication head that may be placed proximate to the patient's body near the IMD <NUM> implant site to improve the quality or security of communication between IMD <NUM> and external computing device <NUM>. Communication between external computing device <NUM> and IMD <NUM> may occur during power transmission or separate from power transmission.

In some examples, IMD <NUM>, in response to commands from external computing device <NUM>, delivers electrical stimulation therapy according to a plurality of therapy stimulation programs to a target tissue site of the spinal cord <NUM> of patient <NUM> via electrodes <NUM> on leads <NUM>. In some examples, IMD <NUM> modifies therapy stimulation programs as therapy needs of patient <NUM> evolve over time. For example, the modification of the therapy stimulation programs may cause the adjustment of at least one parameter of the plurality of informed pulses. When patient <NUM> receives the same therapy for an extended period, the efficacy of the therapy may be reduced. In some cases, parameters of the plurality of informed pulses may be automatically updated.

In the example of <FIG>, IMD <NUM> described as performing a plurality of processing and computing functions. However, external computing device <NUM> instead may perform one, several, or all of these functions. In this alternative example, IMD <NUM> functions to relay sensed signals to external computing device <NUM> for analysis, and external computing device <NUM> transmits instructions to IMD <NUM> to adjust the one or more parameters defining the electrical stimulation therapy based on analysis of the sensed signals. For example, IMD <NUM> may relay the sensed signal indicative of an ECAP to external computing device <NUM>. External computing device <NUM> may compare the parameter value of the ECAP to the target ECAP characteristic value, and in response to the comparison, external computing device <NUM> may instruct IMD <NUM> to adjust one or more stimulation parameter that defines the electrical stimulation informed pulses and, in some examples, control pulses, delivered to patient <NUM>.

After initially implanting IMD <NUM> in patient <NUM>, a caregiver, e.g., the health care provider, may determine the parameters that will relieve the symptoms for patient <NUM>, e.g., reduce or eliminate pain, tremors, and so on. Using a user interface for external computing device <NUM>, the caregiver may select various parameters, such as pulse magnitude, pulse width, burst type, pulse shape, ON-time, OFF-time and so on. The caregiver may use external computing device <NUM> to send instructions to program IMD <NUM> to operate using the selected parameters. In this disclosure, ON-time refers to when IMD <NUM> is operating to deliver electrical stimulation therapy, such as one or more pulse trains. OFF-time refers to when IMD <NUM> withholds delivery, e.g., of the one or more pulse trains. In some examples, during OFF-time IMD <NUM> may cease all stimulation delivery.

Using user interface of external computing device <NUM>, a user may start the procedure to balance clinical efficacy, e.g., to relieve symptoms of patient <NUM>, with reducing battery consumption. Reduced battery consumption may be an advantage for patient <NUM> because reducing battery usage may mean longer times between recharge cycles or longer times between device replacement for non-rechargeable devices with a primary cell. The system of this disclosure may also provide other advantages, such as reduce time demand for the health care provider while at the same time allows the patient control of the system to set the parameters specific to the patient. The system of this disclosure may also allow the patient so change the ON/OFF cycling parameters any time the patient may want.

Processing circuitry of system <NUM> may cause electrical stimulation circuitry of an implantable medical device (IMD), to output electrical stimulation therapy to a patient via electrodes implanted near target tissue of the patient <NUM>, e.g., a target nerve, muscle tissue, and so on. As described above, the electrical stimulation therapy may be defined by various parameters including ON-time and OFF-time. A reduced ON-time and increased OFF-time may reduce battery consumption.

Processing circuitry of system <NUM> may increment the OFF-time by a first predetermined duration. The new OFF-time will be the previous OFF-time, plus incremental duration. For example, the processing circuitry may increment a <NUM> second OFF-time by ten seconds, fifteen seconds, thirty seconds or some other duration. The processing circuitry may receive input the user interface, e.g., of external computing device <NUM> describing the state of symptoms of the patient. For example, patient <NUM> may report that increasing the OFF-time had no noticeable effect on their symptoms, in other words, increasing the OFF-time did not cause the patient's symptoms to return. In other examples, the state of the symptoms may be measurable, e.g., by measuring blood flow, heart rate, or some other biological characteristic, rather than the perception of patient <NUM>.

Responsive to receiving input that the symptoms of the patient have not returned, the processing circuitry may again OFF-time by the predetermined duration. In some examples, the processing circuitry of external computing device <NUM> may perform the functions of the procedure. That is, the processing circuitry of external computing device <NUM> may execute instructions to receive the input describing the state of symptoms of the patient, determine whether or not a parameter needs to be changed, and re-program IMD <NUM> with the new parameters, e.g., via telemetry communications.

In other examples, the processing circuitry of IMD <NUM> may execute instructions to receive the input describing the state of symptoms of the patient and determine whether or not a parameter needs to be changed. For example, external computing device <NUM> may receive an indication via a user interface for computing device <NUM> describing the state of symptoms of the patient, e.g., symptoms returned or symptoms have not returned after adjusting a parameter. External device <NUM> may send the indication to IMD <NUM>, rather than reprogramming IMD <NUM>. Instead, processing circuitry of IMD <NUM> may receive the indication describing the state of symptoms of the patient and make adjustments to the parameter, e.g., increment or decrease the OFF-time, based in programming instructions executed by the processing circuitry of IMD <NUM>.

Responsive to receiving input that the symptoms of the patent have returned, the processing circuitry of system <NUM> may decrease the OFF-time by a predetermined second duration. In some examples, the second duration may be less than the first duration. For example, the processing circuitry may iteratively adjust the OFF-time in, e.g., twenty-second increments, for each test cycle until the processing circuitry receives an indication that the patient's symptoms have returned. Then the processing circuitry may iteratively decrease the OFF-time in smaller increments, e.g., in five-second or ten-second increments for each test cycle until the therapy begins to relieve the patient's symptoms again. In this disclosure, a 'test cycle' may include a change in a therapy parameter, delivery of therapy under the changed parameters, and checking for whether or not the patient's symptoms have returned, e.g., by asking the patient, or by taking a measurement, as described above. In other words, the processing circuitry of system <NUM> may receive input via the user interface describing the state of symptoms of the patient, and after decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have returned, the processing circuitry may decrease the OFF-time again by the second duration.

Once the OFF-time is set such that the therapy relieves the patient's, the processing circuitry of system <NUM> may perform a similar procedure by iteratively adjusting the ON-time parameter. In other words, after decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have not returned, the processing circuitry may decrease the ON-time by a third duration, e.g., ten-second, thirty-second, five-minute or some other duration. In some examples, the third duration to decrease the ON-time may be the same duration used to increase the OFF-time, described above.

Similar to adjusting the OFF-time parameter, the processing circuitry may receive input via the user interface describing the state of symptoms of the patient, and responsive to receiving input that the symptoms of the patient have not returned, for the next test cycle, the processing circuitry may again decrease the ON-time by the predetermined duration. For a test cycle in which the processing circuitry of system <NUM> receives an input that the symptoms of the patent have returned, the processing circuitry may increment the ON-time by a fourth duration. In some examples, the fourth duration may be less than or equal to the third duration, e.g., the processing circuitry may increment the ON-time by one-third, one-half etc. of the duration used to decrease the ON-time. The processing circuitry my increase the ON-time until the delivered therapy begins relieving the patient's symptoms. In other words, after incrementing the ON-time by the fourth duration and after receiving input that the symptoms of the patient have not returned, the processing circuitry may cause the electrical stimulation circuitry to output the electrical stimulation therapy according to the determined parameters. In the example techniques described in this disclosure, the instructions executed by the processing circuitry may cause system <NUM> to execute several test cycles, gradually increasing the OFF-time, then gradually decreasing the ON-time to ensure IMD <NUM> delivers electrical stimulation therapy without using energy that does not maintain or improve clinical efficacy. Such a procedure may deliver improved patient care by reducing battery usage and extending battery life.

In some examples, IMD <NUM> may include 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 <NUM> may include the stimulation circuitry and the sensing circuitry, but external computing device <NUM> or other external device may include the processing circuitry that at least determines the posture state of the patient. IMD <NUM> may transmit the sensed ECAP signals, or data representing the ECAP signal, to external computing device <NUM>, for example. Therefore, the processes described herein may be performed by multiple devices in a distributed system. In some examples, system <NUM> may include one or more electrodes that deliver and/or sense electrical signals. Such electrodes may be configured to sense the ECAP signals. In some examples, the same electrodes may be configured to sense signals representative of transient movements of the patient. In other examples, other sensors, such as accelerometers, gyroscopes, or other movement sensors may be configured to sense movement of the patient that indicates the patient may have transitioned to a different posture state, by which the target characteristic value may have changed accordingly.

Although in one example IMD <NUM> takes the form of an SCS device, in other examples, IMD <NUM> 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 used to determine parameters that affect stimulation thresholds (e.g., perception thresholds and detection thresholds) associated any one of the aforementioned IMDs and then use a stimulation threshold to inform the intensity (e.g., stimulation levels) of therapy. For example, changing stimulation parameters such as the number of pulses in a burst, the number of bursts over a duration, the pulse width of a pulse in a burst, the ON-time, the OFF-time, a pattern of pulses over a duration and other parameters may change the intensity as well as the efficacy of the therapy to relieve the symptoms.

<FIG> is a block diagram illustrating example components of the medical device of <FIG>. Implantable medical device <NUM> is an example of IMD <NUM> described above in relation to <FIG>. In the example illustrated in <FIG>, IMD <NUM> includes temperature sensor <NUM>, coil <NUM>, processing circuitry <NUM>, therapy and sensing circuitry <NUM>, recharge circuitry <NUM>, memory <NUM>, telemetry circuitry <NUM>, power source <NUM>, and one or more sensors <NUM>, such as an accelerometer. In other examples, IMD <NUM> may include a greater or a fewer number of components, e.g., in some examples, IMD <NUM> may not include temperature sensor <NUM> or sensors <NUM>. In general, IMD <NUM> may comprise any suitable arrangement of hardware, alone or in combination with software and/or firmware, to perform the various techniques described herein attributed to IMD <NUM> and processing circuitry <NUM>, and any equivalents thereof.

Processing circuitry <NUM> of IMD <NUM> may include one or more processors, such as 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. IMD <NUM> may include a memory <NUM>, such as 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, comprising executable instructions for causing the processing circuitry <NUM> to perform the actions attributed to this circuitry. Moreover, although processing circuitry <NUM>, therapy and sensing circuitry <NUM>, recharge circuitry <NUM>, telemetry circuitry <NUM>, and temperature sensor <NUM> are described as separate modules, in some examples, some combination of processing circuitry <NUM>, therapy and sensing circuitry <NUM>, recharge circuitry <NUM>, telemetry circuitry <NUM> and temperature sensor <NUM> are functionally integrated. In some examples, processing circuitry <NUM>, therapy and sensing circuitry <NUM>, recharge circuitry <NUM>, telemetry circuitry <NUM>, and temperature sensor <NUM> correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units. In this disclosure, therapy, and sensing circuitry <NUM> may be referred to as therapy circuitry <NUM>, for simplicity.

Memory <NUM> may store therapy programs or other instructions that specify therapy parameter values for the therapy provided by therapy circuitry <NUM> and IMD <NUM>. In some examples, memory <NUM> may also store temperature data from temperature sensor <NUM>, instructions for recharging rechargeable power source <NUM>, thresholds, instructions for communication between IMD <NUM> and an external computing device, or any other instructions required to perform tasks attributed to IMD <NUM>. Memory <NUM> may be configured to store instructions for communication with and/or controlling one or more temperature sensors of temperature sensor <NUM>.

For example, memory <NUM> may store programming settings for parameters such as electrical stimulation therapy output magnitude, pulse width, ON-time, OFF-time and so on. Memory <NUM> may determine whether a sensed bioelectrical signal is valid, such as and ECAP or other signal in response to an output electrical stimulation therapy event. Memory <NUM> may store programming instructions that when executed by processing circuitry <NUM> cause processing circuitry <NUM> to cause electrical stimulation circuitry therapy circuitry <NUM> to deliver electrical stimulation therapy to a target tissue, e.g., a target nerve of a patient.

In some examples, the programming instructions may cause processing circuitry <NUM> to increment the OFF-time by a first duration and receive input via the user interface, which may indicate the state of symptoms of the patient. As described above in relation to <FIG>, in some examples processing circuitry <NUM> may receive the indication of whether the patient symptoms have returned after a change to a parameter and determine whether to increment or decrease the OFF-time or ON-time for each test cycle. In other examples, processing circuitry <NUM> may simply receive a programming instruction from, e.g., external computing device <NUM>, to adjust the OFF-time, ON-time or other parameter during each test cycle. IMD <NUM> may receive the indication of the patient symptoms, and programming command to adjust therapy parameters via telemetry circuitry <NUM>. In some examples, external computing device <NUM> may also communicate with processing circuitry <NUM> of IMD <NUM> inductively via coil <NUM> and recharge circuitry <NUM>. In this manner, processing circuitry <NUM> may be described as being operatively coupled to the user interface of external device <NUM>.

Therapy and sensing circuitry <NUM> may generate and deliver electrical stimulation under the control of processing circuitry <NUM>. In some examples, processing circuitry <NUM> controls therapy circuitry <NUM> by accessing memory <NUM> to selectively access and load at least one of the stimulation programs to therapy circuitry <NUM>. For example, in operation, processing circuitry <NUM> may access memory <NUM> to load one of the stimulation programs to therapy circuitry <NUM>. In such examples, relevant stimulation parameters may include a voltage amplitude, a current amplitude, a pulse rate, a pulse width, a duty cycle, or the combination of electrodes 217A, 217B, 217C, and 217D (collectively "electrodes <NUM>") that therapy circuitry <NUM> may use to deliver the electrical stimulation signal as well as sense biological signals. In other examples, IMD <NUM> may have more or fewer electrodes than the four shown in the example of <FIG>. In some examples electrodes <NUM> may be part of or attached to a housing of IMD <NUM>, e.g., a leadless electrode. In other examples, one or more of electrodes <NUM> may be part of a lead implanted in or attached to a patient to sense biological signals and/or deliver electrical stimulation, as described above in relation to <FIG>.

In some examples, one or more electrodes connected to therapy circuitry <NUM> may connect to one or more sensing electrodes, e.g., attached to a housing of IMD <NUM>. In some examples the electrodes may be configured to detect the evoked motor response caused by the electrical stimulation therapy event, or other bioelectrical signals such as ECAPs, impedance and so on.

IMD <NUM> also includes components to receive power to recharge rechargeable power source <NUM> when rechargeable power source <NUM> has been at least partially depleted. As shown in <FIG>, IMD <NUM> includes coil <NUM> and recharge circuitry <NUM> coupled to rechargeable power source <NUM>. Recharge circuitry <NUM> may be configured to charge rechargeable power source <NUM> with the selected power level determined by either processing circuitry <NUM> or an external charging device, such as external computing device <NUM> described above in relation to <FIG>. Recharge circuitry <NUM> may include any of a variety of charging and/or control circuitry configured to process or convert current induced in coil <NUM> into charging current to charge power source <NUM>.

Secondary coil <NUM> may include a coil of wire or other device capable of inductive coupling with a primary coil disposed external to patient <NUM>. Although secondary coil <NUM> is illustrated as a simple loop of in <FIG>, secondary coil <NUM> may include multiple turns of conductive wire. Secondary coil <NUM> may include a winding of wire configured such that an electrical current can be induced within secondary coil <NUM> from a magnetic field. The induced electrical current may then be used to recharge rechargeable power source <NUM>.

Recharge circuitry <NUM> may include one or more circuits that process, filter, convert and/or transform the electrical signal induced in the secondary coil to an electrical signal capable of recharging rechargeable power source <NUM>. For example, in alternating current induction, recharge circuitry <NUM> may include a half-wave rectifier circuit and/or a full-wave rectifier circuit configured to convert alternating current from the induction to a direct current for rechargeable power source <NUM>. The full-wave rectifier circuit may be more efficient at converting the induced energy for rechargeable power source <NUM>. However, a half-wave rectifier circuit may be used to store energy in rechargeable power source <NUM> at a slower rate. In some examples, recharge circuitry <NUM> may include both a full-wave rectifier circuit and a half-wave rectifier circuit such that recharge circuitry <NUM> may switch between each circuit to control the charging rate of rechargeable power source <NUM> and temperature of IMD <NUM>. In some examples recharge circuitry <NUM> may also include communication circuitry.

Rechargeable power source <NUM> may include one or more capacitors, batteries, and/or other energy storage devices. Rechargeable power source <NUM> may deliver operating power to the components of IMD <NUM>. In some examples, rechargeable power source <NUM> may include a power generation circuit to produce the operating power. Rechargeable power source <NUM> may be configured to operate through many discharge and recharge cycles. Rechargeable power source <NUM> may also be configured to provide operational power to IMD <NUM> during the recharge process. In some examples, rechargeable power source <NUM> may be constructed with materials to reduce the amount of heat generated during charging. In other examples, IMD <NUM> may be constructed of materials and/or using structures that may help dissipate generated heat at rechargeable power source <NUM>, recharge circuitry <NUM>, and/or secondary coil <NUM> over a larger surface area of the housing of IMD <NUM>.

Although rechargeable power source <NUM>, recharge circuitry <NUM>, and secondary coil <NUM> are shown as contained within the housing of IMD <NUM>, in alternative implementations, at least one of these components may be disposed outside of the housing. For example, in some implementations, secondary coil <NUM> may be disposed outside of the housing of IMD <NUM> to facilitate better coupling between secondary coil <NUM> and the primary coil of external charging device. In other examples, power source <NUM> may be a primary power cell and IMD <NUM> may not include recharge circuitry <NUM> and secondary coil <NUM>, which may also be called recharge coil <NUM> in this disclosure.

Processing circuitry <NUM> may also control the exchange of information with an external computing device using telemetry circuitry <NUM>. Telemetry circuitry <NUM> may be configured for wireless communication using radio frequency protocols, such as BLUETOOTH, or similar RF protocols, as well as using inductive communication protocols. Telemetry circuitry <NUM> may include one or more antennas configured to communicate with an external charging device, for example. Processing circuitry <NUM> may transmit operational information and receive therapy programs or therapy parameter adjustments via telemetry circuitry <NUM>. Also, in some examples, IMD <NUM> may communicate with other implanted devices, such as stimulators, control devices, or sensors, via telemetry circuitry <NUM>. In addition, telemetry circuitry <NUM> may be configured to control the exchange of information related to sensed and/or determined temperature data, for example temperatures sensed by and/or determined from temperatures sensed using temperature sensor <NUM>. In some examples, telemetry circuitry <NUM> may communicate using inductive communication, and in other examples, telemetry circuitry <NUM> may communicate using RF frequencies separate from the frequencies used for inductive charging.

In some examples, processing circuitry <NUM> may transmit additional information to an external computing device related to the operation of rechargeable power source <NUM>. For example, processing circuitry <NUM> may use telemetry circuitry <NUM> to transmit indications that rechargeable power source <NUM> is completely charged, rechargeable power source <NUM> is fully discharged, the amount of charging current output by recharge circuitry <NUM> e.g., to power source <NUM>, or any other charge status of rechargeable power source <NUM>. In some examples, processing circuitry <NUM> may use telemetry circuitry <NUM> to transmit instructions to an external charging device, including instructions regarding further control of the charging session, for example instructions to lower the power level or to terminate the charging session, based on the determined temperature of the housing/external surface of the IMD.

<FIG> is a block diagram of an example an external computing device of <FIG>. External charging device <NUM> in of <FIG> is an example of external computing device <NUM> described above in relation to <FIG>. In some examples, external charging device <NUM> may be described as a hand-held device, in other examples, external charging device <NUM> may be a larger or a non-portable device. In addition, in other examples external charging device <NUM> may be included as part of an external programmer or include functionality of an external programmer. External charging device <NUM> may also be referred to as recharger <NUM>, or programmer <NUM> in this disclosure.

As shown in the example of <FIG>, external charging device <NUM> includes two separate components. Housing <NUM> encloses components such as a processing circuitry <NUM>, memory <NUM>, user interface <NUM>, telemetry circuitry <NUM>, audio output circuitry <NUM> and power source <NUM>. Charging head <NUM>, also called charging wand <NUM>, may include charging circuitry <NUM>, temperature sensor <NUM>, and coil <NUM>. Housing <NUM> is electrically coupled to charging head <NUM> via charging cable <NUM>. Housing <NUM> may also include charging circuitry <NUM> and coil <NUM>, which is an example of coil <NUM> described above in relation to <FIG>.

In some examples, separate charging wand <NUM> may facilitate positioning of coil <NUM> over coil <NUM> of IMD <NUM>. In some examples, charging circuitry <NUM> and/or coil <NUM> may be integrated within housing <NUM> in other examples, as described above in relation to <FIG>. In other examples, recharger <NUM> may not include charging wand <NUM>. Memory <NUM> may store instructions that, when executed by processing circuitry <NUM>, causes processing circuitry <NUM> and external charging device <NUM> to provide the functionality ascribed to external charging device <NUM> throughout this disclosure, and/or any equivalents thereof. Coil <NUM> and coil <NUM> may also be referred to as an antenna.

In some examples, recharger <NUM> may include secondary processing circuitry <NUM>, which may control telemetry circuitry <NUM>, as well as perform other functions. Some other functions may include error checking of the operation of primary processing circuitry <NUM>.

External charging device <NUM> may also include one or more temperature sensors, illustrated as temperature sensor <NUM>, similar to temperature sensor <NUM> of <FIG>. As shown in <FIG>, temperature sensor <NUM> may be disposed within charging head <NUM>. In other examples, one or more temperature sensors of temperature sensor <NUM> may be disposed within housing <NUM>. For example, charging head <NUM> may include one or more temperature sensors positioned and configured to sense the temperature of coil <NUM> and/or a surface of the housing of charging head <NUM>. In some examples, external charging device <NUM> may not include temperature sensor <NUM>.

In general, external charging device <NUM> comprises any suitable arrangement of hardware, alone or in combination with software and/or firmware, to perform the techniques ascribed to external charging device <NUM>, and processing circuitry <NUM>, user interface <NUM>, telemetry circuitry <NUM>, and charging circuitry <NUM> of external charging device <NUM>, and/or any equivalents thereof. In various examples, external charging device <NUM> may include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. External charging device <NUM> also, in various examples, may include a memory <NUM>, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, a hard disk, a CD-ROM, comprising executable instructions for causing the one or more processors to perform the actions attributed to them. Moreover, although processing circuitry <NUM>, telemetry circuitry <NUM>, charging circuitry <NUM>, and temperature sensor <NUM> are described as separate modules, in some examples, processing circuitry <NUM>, telemetry circuitry <NUM>, charging circuitry <NUM>, and/or temperature sensor <NUM> are functionally integrated. In some examples, processing circuitry <NUM>, telemetry circuitry <NUM>, charging circuitry <NUM>, and/or temperature sensor <NUM> correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

Memory <NUM> may store instructions that, when executed by processing circuitry <NUM>, cause processing circuitry <NUM> and external charging device <NUM> to provide the functionality ascribed to external charging device <NUM> throughout this disclosure, and/or any equivalents thereof. For example, memory <NUM> may include instructions that cause processing circuitry <NUM> to control the power level used to charge IMD <NUM> in response to the determined temperatures for the housing/external surface(s) of IMD <NUM>, as communicated from IMD <NUM>, or instructions for any other functionality. Memory <NUM> may include a record of selected power levels, sensed temperatures, determined temperatures, or any other data related to charging rechargeable power source <NUM>, described above in relation to <FIG>.

Processing circuitry <NUM> may, when requested, transmit any stored data in memory <NUM> to another computing device for review or further processing, such as to network computing device <NUM>. Processing circuitry <NUM> may be configured to access memory, such as memory <NUM> of IMD <NUM> and/or memory <NUM> of external charging device <NUM>, to retrieve information comprising instructions, formulas, programmed settings and parameters for electrical stimulation therapy, as well as determined values for one or more constants.

Network computing device <NUM> act as a server, such as a cloud based server, or a household server. In some examples network computing device <NUM> may be a tablet computer, laptop computer, desktop computer, mobile phone and so on. Network computing device <NUM> may include a user interface which may display outputs and accept inputs, such as the state of a patient's symptoms, as described above in relation to <FIG> and <FIG>. In this manner, a user interface of network computing device <NUM> may be described as being operatively coupled to processing circuitry <NUM> as well as to processing circuitry <NUM> depicted in <FIG>.

User interface <NUM> may also receive user input via user interface <NUM>. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. The input may change programmed settings, start or stop therapy, request starting or stopping a recharge session, a desired level of charging, or one or more statistics related to charging rechargeable power source <NUM> (e.g., the cumulative thermal dose). In this manner, user interface <NUM> may allow the user to view information related to the operation of IMD <NUM>. As described above in relation to <FIG> and <FIG>, user interface <NUM> may receive an input from a user to start the procedure to balance clinical efficacy with reducing battery consumption. For each test cycle, user interface <NUM> may display a query to the user regarding the state of the patient's symptoms, e.g., have the patient's symptoms returned after adjusting a parameter. Processing circuitry <NUM> may receive the user input and determine whether to increment or decrease the ON-time or OFF-time. In some examples, processing circuitry <NUM> may send a programming command to the implanted device, e.g., IMD <NUM> or IMD <NUM> depicted in <FIG> and <FIG>, to adjust the ON-time or OFF-time in response to the received user input.

Charging circuitry <NUM> may include one or more circuits that generate an electrical signal, and an electrical current, within primary coil <NUM>. Charging circuitry <NUM> may generate an alternating current of specified amplitude and frequency in some examples. In other examples, charging circuitry <NUM> may generate a direct current. In any case, charging circuitry <NUM> may be capable of generating electrical signals, and subsequent magnetic fields, to transmit various levels of power to IMD <NUM>. In this manner, charging circuitry <NUM> may be configured to charge rechargeable power source <NUM> of IMD <NUM> with the selected power level.

Power source <NUM> may deliver operating power to the components of external charging device <NUM>. Power source <NUM> may also deliver the operating power to drive primary coil <NUM> during the charging process. Power source <NUM> may include a battery and a power generation circuit to produce the operating power. In some examples, a battery of power source <NUM> may be rechargeable to allow extended portable operation. In other examples, power source <NUM> may draw power from a wired voltage source such as a consumer or commercial power outlet.

Telemetry circuitry <NUM> supports wireless communication between IMD <NUM> and external charging device <NUM> under the control of processing circuitry <NUM>. Telemetry circuitry <NUM> may also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. In some examples, telemetry circuitry <NUM> may be substantially similar to telemetry circuitry <NUM> of IMD <NUM> described herein, providing wireless communication via an RF or proximal inductive medium, e.g., using coil <NUM>. In some examples, telemetry circuitry <NUM> may include an antenna <NUM>, which may take on a variety of forms, such as an internal or external antenna. Although telemetry modules <NUM> and <NUM> may each include dedicated antennas for communications between these devices, telemetry modules <NUM> and <NUM> may instead, or additionally, be configured to utilize inductive coupling from coils <NUM> and <NUM> to transfer data.

Examples of local wireless communication techniques that may be employed to facilitate communication between external charging device <NUM> and IMD <NUM> include radio frequency and/or inductive communication according to any of a variety of standard or proprietary telemetry protocols, or according to other telemetry protocols such as the IEEE <NUM>. 11x or Bluetooth specification sets. In this manner, other external devices may be capable of communicating with external charging device <NUM> without needing to establish a secure wireless connection.

As described above in relation to <FIG>, processing circuitry <NUM> may use any one or more system metrics to determine power transfer to IMD <NUM>. In some examples, IMD <NUM> may send a signal indicating an amount of current output by the recharge circuitry of IMD <NUM>. In other examples, processing circuitry <NUM> may calculate other system metrics, such as alignment of coil <NUM> to coil <NUM> of IMD <NUM> using any of several techniques, including heat calculations, temperature measurements, detection of metal, and so on.

<FIG> is a flow chart illustrating an example operation of the medical system with the user-driven auto cycling procedure of this disclosure. The blocks shown in the example of <FIG> will be described in terms of <FIG> and <FIG> and the medical system depicted in <FIG>, which includes one or more electrical leads with one or more electrodes in contact with tissue of a patient connected to an implantable medical device.

At some time after implanting an IMD, e.g., IMD <NUM> or IMD <NUM> depicted in <FIG> or <FIG>, a user may initialize the procedure of this disclosure to reduce battery power used to deliver electrical stimulation therapy while maintaining clinical efficacy to relieve the patient's symptoms. The user may start this procedure during implant recovery, during a follow-up visit and as many times during the life of the IMD as desired. Also, the example of <FIG> is just one possible implementation of the techniques of this disclosure. In other examples, more or fewer steps may be included, and the order of the steps may be different than shown in <FIG>.

A user interface of system <NUM> may be configured to receive input from a user to start the auto cycling procedure (<NUM>), as well as receive the input describing the state of symptoms of the patient. As described above, the user interface may include user interface <NUM> on external computing device <NUM>, or a user interface on a network computing device, such as a tablet computer, smart phone and so on. Primary processing circuitry <NUM> may receive the input to initiate the test (<NUM>) and execute programming instructions to step through the procedure.

In some examples, a health care provider may have determined the electrical stimulation therapy parameters and programmed IMD <NUM> with the parameters to cause the electrical stimulation circuitry to output electrical stimulation therapy to the patient. As described above, parameters may include magnitude, ON-time, OFF-time and so on. In some examples, for the auto cycling test, processing circuitry of system <NUM> may use the initial settings to set stimulation ON-time and set the stimulation OFF-time (<NUM>). Therefore an example ON-time of X and OFF-time of Y may be the initially selected ON-time and OFF-time set by the health care provider. In other examples, based on programming instructions, e.g., stored at memory <NUM>, the processing circuitry may set the auto cycling ON-time of X and OFF-time of Y to values different from the initial values set by the health care provider.

In some examples, primary processing circuitry <NUM> of external computing device <NUM> may execute the steps shown in <FIG> and only send updated parameters to IMD <NUM> via communication circuitry, e.g., telemetry circuitry <NUM>. In other examples, processing circuitry <NUM> of IMD <NUM> may execute some or most of the steps shown in <FIG>. To simplify the description, this disclosure will assume that processing circuitry <NUM> will execute the programming instructions to perform the steps of the auto cycling procedure of <FIG>.

After setting stimulation ON-time and the stimulation OFF-time (<NUM>), processing circuitry <NUM> may pause and wait for input describing the state of symptoms of the patient. Responsive to receiving input that the symptoms of the patient have not returned (NO branch of <NUM>), processing circuitry <NUM> may increment the OFF-time by a first duration (<NUM>), e.g., increase by A seconds. In other words, processing circuitry <NUM> sets the OFF-time to Y + A, then pauses again waiting for input regarding the patient's symptoms.

Responsive to receiving input via the user interface that the symptoms of the patient have not returned, processing circuitry <NUM> may increment the OFF-time again (<NUM>) by the first duration, e.g., by another A seconds, thereby setting the OFF-time to Y + 2A. Note that incrementing the OFF-time by a set, predetermined amount after each test cycle as shown in the example of <FIG> is only one possible implementation of the auto cycling procedure. In other examples, the incremental step may gradually increase, gradually decrease, be set based on a relationship between step size and range of values for the OFF-time parameter, and so on.

Responsive to receiving input that the symptoms of the patent have returned (YES branch of <NUM>), processing circuitry <NUM> may decrease the OFF-time by a second duration (<NUM>), e.g., reduce the OFF-time parameter by B seconds. In some examples, B may be less than A, as described above, while in other examples B may the same as A. The value of the increments for A and B may be any value. Some examples may include A is five seconds while B is two seconds, A is set to <NUM> seconds and B is set to <NUM> seconds, A is thirty seconds and B is fifteen seconds, and so on.

After reducing the OFF-time, processing circuitry <NUM> may pause and wait to receive input via the user interface describing the state of symptoms of the patient. In some examples, after decreasing the OFF-time by the second duration, and receiving input via the user interface that the symptoms of the patient have still returned, i.e., that decreasing the OFF-time by B seconds did not relieve the patient's symptoms, then processing circuitry <NUM> may decrease the OFF-time again by the second duration (YES branch of <NUM>).

After decreasing the OFF-time by the second duration and responsive to receiving input that the symptoms of the patient have not returned (NO branch of <NUM>), processing circuitry <NUM> may start adjusting the ON-time parameter. Processing circuitry <NUM> may decrease the ON-time by a third duration (<NUM>). In the example of <FIG>, processing circuitry <NUM> decreases the ON-time by A seconds, e.g., the same increment as for increasing the OFF-time. However, in other examples, the increment to decrease the ON-time may be different from the increment to increase the OFF-time.

Processing circuitry <NUM> may pause to receive input via the user interface describing the state of symptoms of the patient. Processing circuitry <NUM> may begin the next test cycle after receiving input that the symptoms of the patient have not returned (NO branch of <NUM>), again decrease the ON-time again by the third duration (<NUM>), resulting in an ON-time of X - 2A.

Processing circuitry <NUM> may continue to decrease the ON-time and pause until, responsive to receiving input that the symptoms of the patent have returned (YES branch of <NUM>), processing circuitry <NUM> may increment the ON-time by a fourth duration (<NUM>), e.g., by B seconds. In the example of <FIG>, the increment amount (B) after the patient symptoms have returned is the same as the decrease amount (B) shown in <NUM> for the OFF-time. However, in other examples, the values may be different.

After pausing to receive input via the user interface describing the state of symptoms of the patient, processing circuitry <NUM> may continue incrementing the ON-time by B seconds (YES branch of <NUM>), until receiving input that the symptoms of the patient have NOT returned, e.g., the ON-time and OFF-time settings relieve the patient's symptoms (NO branch of <NUM>). As noted above, relieving the patient's symptoms may be patient dependent and may not result in complete relief. For example, the electrical stimulation therapy may provide partial pain relief, a reduction in tremors, an improvement in gait, and so on. Once the parameters for the electrical stimulation therapy provide clinical efficacy, processing circuitry <NUM> may end the test procedure (<NUM>) and cause the electrical stimulation circuitry to output the electrical stimulation therapy according to the parameters, including ON-time and OFF-time.

In some examples, the steps of <FIG> may be performed multiple times for an IMD and a patient. For example, as the patient's conditions progress, the therapy delivery may change to provide relief. In some examples, a clinician may execute the steps of FIG. <NUM> during a follow up health care visit. In other examples, a clinician or other caregiver may trigger the steps of <FIG> remotely, such as via network computing device <NUM>.

Claim 1:
A system (<NUM>) comprising
a user interface configured to receive input from a user; and
processing circuitry (<NUM>) configured to
control electrical stimulation circuitry (<NUM>) to output electrical stimulation to a patient,
wherein the electrical stimulation is defined by parameters, the parameters comprising ON-time and OFF-time, and
wherein the electrical stimulation is configured to relieve symptoms of the patient; and
increment the OFF-time by a first duration;
characterized in that processing circuitry is further configured to:
receive input via the user interface, the first input describing that the symptoms of the patient have not returned;
responsive to receiving input that the symptoms of the patient have not returned increment the OFF-time by the first duration;
receive input describing that the symptoms of the patient have returned;
responsive to receiving input that the symptoms of the patent have returned, decrease the OFF-time by a second duration.