Stimulation systems with waveforms for therapy

Abstract

Methods, systems, and devices are configured delivering one or more sequences of different pulse trains to a patient. For example, a system includes processing circuitry configured to control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase. The processing circuitry can also be configured to control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

Description

STIMULATION SYSTEMS WITH WAVEFORMS FOR THERAPY

[0001] This application is a PCT application claiming priority to, and the benefit of, U.S. Provisional Patent Application No. 63 / 712,112, filed October 25, 2024, the entire contents of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The disclosure relates to medical devices and, more particularly, medical devices that deliver therapy to a patient.BACKGROUND

[0003] Bladder dysfunction, such as overactive bladder, urgency, or urinary incontinence, are problems that may afflict people of all ages, genders, and races. Various muscles, nerves, organs and conduits within the pelvic floor cooperate to collect, store and release urine. A variety of disorders may compromise urinary or bowel function, and contribute to an overactive bladder, urgency, urinary incontinence, urinary retention, fecal incontinence, or other conditions. Many of the disorders may be associated with aging, injury, or illness.

[0004] Urinary incontinence may include urge incontinence, urinary frequency, and stress incontinence. In some examples, urge incontinence may be caused by disorders of peripheral or central nervous systems that control bladder micturition reflexes. Some patients may also suffer from nerve disorders that prevent proper triggering and operation of the bladder, sphincter muscles, or nerve disorders that lead to overactive bladder activities or urge incontinence.

[0005] Urinary incontinence can be attributed to improper sphincter function, either in the internal urinary sphincter or external urinary sphincter. For example, aging can result in weakened sphincter muscles, which may cause incontinence. Nerves running though the pelvic floor stimulate contractility in the sphincter. An improper communication between the nervous system and the urethra or urinary sphincter can result in a bladder dysfunction, such as overactive bladder, urgency, urge incontinence, or another type of urinary incontinence. Nerve disorders, weakened bladder muscles, or obstructions of a urethra may lead urinary retention, in which the patient is unable to empty their bladder completely. Other conditions may include idiopathic bladder dysfunction in which there is an improper communication between the brain and the bladder which can lead to overactive bladder, urgency, and other conditions.SUMMARY

[0006] In general, the disclosure is directed to techniques, devices, and / or systems for generating and delivering a stimulation waveform including repeating pairs of pulses. These stimulation waveforms may be configured to treat various pelvic floor disorders, such us bladder dysfunction (e.g., urge, frequency, or stress incontinence) or bowel dysfunction. For example, a system may be configured to generate and deliver electrical stimulation that includes a pair of pulses that repeats over time. The pair of pulses may include a first pulse that has a first anodic phase following by a shorter, and higher magnitude, cathodic phase. The following second pulse may include a cathodic phase that is longer and lower magnitude than the cathodic phase of the first pulse. The second phase of the second pulse may be an anodic phase that may be an active or passive recharge phase. Each phase of this pair of pulses may be separated by a respective interphase delay. A stimulation waveform that includes pairs of pulses as described herein may inject charge at a relatively high rate which can cause activation of larger diameter nerve fibers and inhibition of smaller diameter nerve fibers in some examples.

[0007] In one example, a system includes processing circuitry configured to: control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; and control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0008] In another example, a method includes controlling, by processing circuitry, stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; and controlling, by the processing circuitry, the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0009] In another example, a non-transitory computer readable storage medium comprising instructions that, when executed, causes processing circuitry to: control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a thirdwidth of the third phase; and control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0010] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0011] FIG. 1 is conceptual diagram illustrating an example system configured to deliver electrical stimulation to a patient, in accordance with the examples of this disclosure.

[0012] FIG. 2 is a conceptual block diagram illustrating an example of an IMD configured to deliver therapy to a patient.

[0013] FIG. 3 is a block diagram illustrating an example external programmer.

[0014] FIG. 4 is a conceptual diagram of an example lead and electrode combinations.

[0015] FIG. 5 is a timing diagram of an example stimulation waveform according to examples of this disclosure.

[0016] FIG. 6 is a graph of bladder holding volumes for different example stimulation waveforms.

[0017] FIG. 7 is a graph of EMG amplitudes detected for different stimulation waveforms.

[0018] FIG. 8 includes graphs of example EMG signals for different stimulation waveforms.

[0019] FIG. 9 is a flow diagram illustrating an example technique for delivering electrical stimulation including a repeating pair of pulses in accordance with examples of this disclosure.DETAILED DESCRIPTION

[0020] The disclosure is directed to techniques, systems, and devices configured to deliver electrical stimulation to a patient that includes various stimulation waveforms of paired pulses. This electrical stimulation may be configured to treat conditions associated with the pelvic floor (e.g., bladder dysfunction or bowel dysfunction). Bladder dysfunction generally refers to a condition of improper functioning of the bladder or urinary tract, and may include, for example, an overactive bladder, urgency, urgency frequency, bladder incontinence, urinary incontinence, urgency frequency, and / or urinary retention. Urgency is a sudden, compelling urge to urinate, and may often, though not always, be associated with urinary incontinence. Overactive bladder may include excessive contractions of the detrusor muscle (e.g., smooth muscle residing in the wall of the bladder) and may be one of the causes for urgency. Urinary incontinence refers to a condition of involuntary loss of urine, and may include urge incontinence, stress incontinence, or both stress and urge incontinence, which may be referred to as mixed urinary incontinence. Asused in this disclosure, the term “urinary incontinence” includes disorders in which urination occurs when not desired, such as stress or urge incontinence (e.g., overactive bladder). Urinary retention, such as non-obstructive urinary retention, refers to a condition in which a patient is unable to empty their bladder completely. Bowel disorders can also include various dysfunction of the bowel that manifests as fecal incontinence, intractable constipation, irritable bowel syndrome, or inflammatory bowel disease for example. Additional pelvic floor disorders include neurogenic bowel / bladder (tremor, Parkinson’s disease, epilepsy, multiple sclerosis, stork, spinal cord injury, neuropathy etc.), sexual dysfunction, obesity, gastroparesis, pelvic pain, chronic pain, and interstitial cystitis.

[0021] In order to void urine, the nervous system and several muscles of the body typically work in concert to expel urine from the bladder. For example, the internal urinary sphincter muscle and the external urinary sphincter muscle relax to allow urine to pass through the openings in these sphincters. In addition, the detrusor muscle in the wall of the bladder contracts to increase the internal bladder pressure and force urine out of the bladder and through the urethra and past the urinary sphincters. Bladder dysfunction can occur when portions of the nervous system that innervate these muscles, or the muscles themselves, impede the voluntary or involuntary mechanisms either preventing the patient from retaining urine until the patient voluntarily decides to urinate or leading to incomplete emptying of the bladder (retention).

[0022] For example, urge incontinence may be caused by dysfunction of peripheral or central nervous systems that control bladder micturition reflexes. Some patients may also suffer from nerve disorders or unknown issues that prevent proper triggering and operation of the bladder (which may include the detrusor muscle), sphincter muscles or nerve disorders that lead to overactive bladder activities or urge incontinence. Additionally, or alternatively, urinary incontinence can be attributed to improper sphincter function, either in the internal urinary sphincter or external urinary sphincter. In some examples, aging can result in weakened sphincter muscles, which may cause incontinence. Nerves running though the pelvic floor stimulate contractility in the sphincter. An improper communication between the nervous system and the urethra or urinary sphincters can result in a bladder dysfunction, such as overactive bladder, urgency, urge incontinence, urgency frequency, urinary retention, or another type of urinary condition.

[0023] Delivery of electrical stimulation can lead to activation and / or suppression of neural and muscular activities, resulting in a therapeutic effect. For example, electrical stimulation can be delivered to the sacral nerve of the patient to reduce symptoms associated with bladder or bowel incontinence. Example sacral nerve stimulation may include continuous pulses that have a 210 microsecond pulse width at 14 Hz pulse frequency. In other stimulation therapies, deepbrain stimulation (DBS) generally includes continuous pulses with a 60 microsecond pulse width and 130 Hz pulse frequency, and spinal cord stimulation may use 200 microsecond pulse width at 30 Hz. All of these continuous pulse rate stimulation examples may be referred to as “tonic stimulation.” Certain patients may be considered a “responder” to this tonic stimulation when a certain percentage of symptom relief is achieved, e.g., a 50% improvement (i.e., reduction) in symptoms. However, some patients may not achieve this level of improvement using tonic stimulation pulses. If a patient does not achieve a threshold level of improvement using stimulation, the patient may not be eligible for chronic stimulation therapy. Furthermore, some patient may be missing out on improved stimulation therapy, and symptom reduction, that may be achieved using stimulation different than tonic stimulation.

[0024] As described herein, various stimulation waveforms may be used as part of stimulation therapy that may provide improved patient response over other types of stimulation, such as tonic stimulation. For example, a system may be configured to generate and deliver electrical stimulation that includes a pair of pulses that repeats over time. Each pulse of the pair of pulses may include at least two phases. In one example, the pair of pulses may include a first pulse that has a anodic phase followed by a cathodic phase. The next pulse, the second pulse, has a cathodic phase followed by an anodic phase. In this manner, the first and second pulses of the pair of pulses have alternating polarities. This alternating polarity may enable the back-to-back cathodic phases to inject a larger charge to tissue.

[0025] In some examples, the second phase of the first pulse of the pair of pulses has a shorter pulse width and a higher magnitude than the first phase of the first pulse. The following second pulse may have a first phase that has a longer pulse width and a lower magnitude than the second phase of the first pulse having the same polarity. The second phase of the second pulse may be an active or passive recharge phase. Each phase of this pair of pulses may be separated by a respective interphase delay, but some phases may not have an interphase delay in some examples. The system may be configured to repeatedly deliver this pair of pulses to the patient according to a schedule, which may be a continuous pulse rate, bursts of two or more pairs of the pulses, cycled pair of pulses on and off, or any other schedule in which the pair of pulses are repeated. In some examples, the system may adjust an amplitude of the pair of pulses which may affect one phase, or multiple phases of the pair of pulses.

[0026] The electrical stimulation described herein may provide one or more advantages. For example, a stimulation waveform that includes pairs of pulses as described herein may inject charge at a relatively high rate which can cause activation of larger diameter nerve fibers and inhibition of smaller diameter nerve fibers in some examples. This preferential activation of larger diameter nerve fibers while inhibiting smaller diameter nerve fibers (e.g., C-fibers) mayprovide benefits for certain therapies, such as reduced incontinence or reduced pain perception. Moreover, these different stimulation waveforms may be delivered as an alternative to tonic stimulation which may reduce or eliminate habituation to allow the therapy to be effective for the patient for longer periods of time while still maintaining efficacious therapy. In some examples, different stimulation waveforms such as a pair of pulses as described herein may require reduced stimulation durations compared to tonic stimulation due to more effective targeting of certain nerves.

[0027] Implantable medical devices are generally described herein, but the stimulation systems and techniques described herein may utilize chronic neurostimulators or trial neurostimulators that are external, partially implantable, or fully implantable. Chronic neurostimulators are usually implanted and are intended to provide long term therapy (e.g. 5-20 years). For sacral neuromodulation, chronic implants typically include a battery that is connected to a lead with electrodes. Trial neurostimulators are temporary neurostimulators to determine if the patient will be responsive to treatment. Trial neurostimulators are usually an external battery / stimulator that couples to an implanted lead (e.g. a temporary lead), but may also be implanted or partially implanted. Although implantable devise are described herein for illustration, external medical devices may be used in other examples according to the techniques described herein.

[0028] FIG. 1 is conceptual diagram illustrating an example system 10 configured to deliver stimulation therapy to a patient 12 using a repeated stimulation waveform such as a pair of pulses as described herein. Patient 12 ordinarily will be a human patient. In some cases, however, system 10 may be applied to other mammalian or non-mammalian, non-human patients. In some examples, patient 12 experiences bladder dysfunction, such as, for example, improper functioning of a bladder, a urinary sphincter, or a urinary tract, and may include an overactive bladder, urgency, urinary incontinence, urgency frequency, urinary retention, or combinations thereof. In some examples, the systems and techniques described herein may also be applied to the delivery of stimulation to nerves and / or muscles in order to treat bowel disfunction such as fecal incontinence or other disorders.

[0029] System 10 is configured to deliver stimulation that includes repeating a pair of pulses over a period of time, such as according to a schedule (e.g., continuous as a predetermine rate, bursts of pairs of pulses, or at some other pattern). The pair of pulses may start with a different polarity, such as the first pulse beginning with an anodic phase followed by a cathodic phase and the second pulse beginning with a cathodic phase followed by an anodic phase. In addition, in some examples, the second phase of the first pulse in the pair may have a shorter pulse width and larger amplitude than the first phase of the second pulse. Two or more of the phases of the pairof pulses may be separated by an interphase delay in some examples. System 10 can then repeat this pair of pulses over a period of time to the patient in accordance with a schedule. The schedule may include a rate at which to deliver the pair of pulses, where the rate may refer to the frequency that the pair of pulses is delivered. For example, if the rate is 14 Hz, system 10 may deliver 14 pairs of pulses within one second.

[0030] Clinician programmer 20, patient programmer 22, or IMD 14 may be configured to control delivery of a therapy to patient 12 using one or more programs that define the pair of pulses on a repeating basis. Examples of variations of these pair of pulses, or other similar stimulation waveforms, are described in more detail below. While FIG. 1 illustrates an implantable medical device (IMD 14), it is understood that concepts disclosed herein may apply to external or trial neurostimulators.

[0031] IMD 14 may provide electrical stimulation therapy to target tissue site 18 located proximate a sacral nerve, a pudendal nerve, a hypogastric nerve, a pelvic nerve, tibial nerve, saphenous nerve, or another nerve (or even muscle such as a bulbospongiosus muscle) associated with the bladder of patient 12 by generating a programmable electrical stimulation signal (e.g., in the form of electrical pulses) and delivering the electrical stimulation signal to target tissue site 18 via lead 16. In some examples, lead 16 includes one or more stimulation electrodes disposed on the distal end 19 of lead 16 and implanted proximate to target tissue site 18 such that the electrical stimulation is delivered from IMD 14 to target tissue site 18 via the stimulation electrodes. The electrical stimulation therapy may be used to treat bladder dysfunction of patient 12.

[0032] In general, the sacral nerves include five sacral nerves that emerge from the sacrum. In some examples, the sacral vertebrae (S1-S5) may be used to number the sacral nerves. The sacral nerves contribute to the sacral plexus (a network of intersecting nerves that innervates the posterior thigh, part of the lower leg, the foot, and part of the pelvis) and the coccygeal plexus (a network of intersecting nerves near the coccyx bone, e.g., the tailbone, that innervates the skin of the coccyx bone and around the anus). In general, the pudendal nerve is a somatic nerve in the pelvic region, which is a large branch of the sacral plexus. The pudendal nerve innervates the external genitalia, the urinary sphincters, and the anal sphincters. The hypogastric nerves and pelvic nerves innervate the detrusor muscle of the bladder. Stretch receptors of the bladder may send signals to the brain of patient 12 via afferent sensory fibers in sacral nerves that may result in increased activity of the detrusor muscle of the bladder.

[0033] As illustrated in the example of FIG. 1, distal end 19 of lead 16 is implanted proximate to target tissue site 18. In the example shown in FIG. 1, target tissue site 18 is proximate the S3 sacral nerve of patient 12. In this example, in order to implant the distal end 19of lead 16 proximate to the S3 sacral nerve, lead 16 may be introduced into the S3 sacral foramen 24 of sacrum 26 to access the S3 sacral nerve. For some patients, stimulation of the S3 sacral nerve may be effective in treating bladder dysfunction of patient 12. In other examples, distal end 19 may be implanted proximate to a different target tissue site, such as a target tissue site proximate to a different sacral nerve, a pudendal nerve, a hypogastric nerve, a pelvic nerve, an afferent nerve, or another nerve associated with the bladder of patient 12 to treat the bladder dysfunction of patient 12. Distal end 19 of lead 16 may include multiple electrodes, such as four or more electrodes.

[0034] Although FIG. 1 illustrates one lead 16, in some examples, IMD 14 may be coupled to two or more leads, e.g., to facilitate bilateral (e.g., stimulation to sacral nerves on either side of the spinal cord) or multi-lateral stimulation (e.g., stimulation to multiple sacral nerves on the same side of the spinal cord). In some examples, lead 16 may also carry one or more sense electrodes via which IMD 14 can sense one or more physiological parameters (e.g., nerve signals, EMG, or the like) of patient 12, in addition to the one or more stimulation electrodes carried by lead 16. In other examples, the same electrodes used to stimulate may also be used for sensing. In some examples, lead 16 includes a lead body, and proximal end of lead 16 may be electrically coupled to IMD 14 via one or more conductors extending substantially through the lead body between the one or more stimulation electrodes carried by lead 16 and IMD 14. In the case of an external device, the proximal end of lead 16 may be configured to couple to an external medical device, such as trial neurostimulator.

[0035] In the example shown in FIG. 1, lead 16 is cylindrical. One or more electrodes of lead 16 may be ring electrodes, segmented electrodes, or partial ring electrodes. Segmented or partial ring electrodes each extend along an arc less than 360 degrees (e.g., 70-120 degrees) around the outer perimeter of the lead 16, where in some example, multiple electrode segments are disposed around the perimeter of lead 16 at the same axial position of lead 16. In some examples, segmented electrodes may be useful for targeting different fibers of the same or different nerves to generate different physiological effects or for delivering relatively higher frequency stimulation (e.g., about 60 Hertz) and relatively lower frequency stimulation (e.g., about 8 Hertz). In some examples, different pulse width values of one or more phases of one or more pulses of the pair of pulses may be selected in order to selectively stimulate certain nerve fibers while avoiding other nerve fibers (e.g., fibers having different diameters). In some examples, lead 16 may include a paddle-shaped (e.g., a “paddle” lead) portion with a flat or curved surface.

[0036] In some examples, one or more of the electrodes of lead 16 may be cuff electrodes that are configured to extend at least partially around a nerve (e.g., extend axially around an outersurface of a nerve). In some cases, delivering stimulation via one or more cuff electrodes and / or segmented electrodes may help achieve a more uniform electrical field or activation field distribution relative to the nerve in some examples, which may help minimize discomfort to patient 12 that results from the delivery of electrical stimulation. An electrical field represents the areas of a patient anatomical region that are covered by an electrical field during delivery of electrical stimulation to tissue within patient 12. The electrical field may define the volume of tissue that is affected when the electrodes of lead 16, or any other electrodes carried by IMD 14 (e.g., one or more electrodes carried by the housing of IMD 14), are activated. An activation field represents the neurons that will be activated by the electrical field in the neural tissue proximate to the activated electrodes.

[0037] The illustrated numbers and configurations of lead 16 and electrodes carried by lead 16 are merely one example. Different configurations, e.g., different quantities and / or positions of leads and electrodes, are possible. In other examples, IMD 14 may be coupled to additional leads or lead segments having one or more electrodes positioned at different locations in the pelvic region of patient 12. In some examples, lead 16 may have one electrode, two electrodes, three electrodes, four electrodes, or eight electrodes. In other examples, lead 16 may have a combination of ring electrodes and segmented electrodes.

[0038] IMD 14 may be surgically implanted in patient 12 at any suitable location within patient 12, such as within in an abdomen of patient 12. In some examples, the implantation site may be a subcutaneous location in the upper buttocks, side of the lower abdomen, or the side of the lower back. IMD 14 has a biocompatible outer housing, which may be formed from titanium, stainless steel, a liquid crystal polymer, or the like. In some examples, such as with a leadless stimulator, the outer housing may have an electrically insulative coating (e.g., parlyene). In some examples, electrical conductors disposed within the lead body of lead 16 electrically connect electrodes to an electrical stimulation delivery module within IMD 14. In other examples, system 10 may include a leadless electrical stimulator, such as a microstimulator (e.g., a capsule shaped microstimulator), where the leadless electrical stimulator delivers electrical stimulation to target tissue site 18.

[0039] In the example illustrated in FIG. 1, system 10 includes clinician programmer 20 and patient programmer 22. In some examples, one or both programmers 20 and 22 may be wearable communication devices integrated into a remote, key fob, or a wrist watch. In other examples, one or both programmers 20 and 22 may be handheld computing devices, computer workstations, smartphones, personal computers, or networked computing devices. Programmers 20 and / or 22 may be proprietary devices or computing devices configured to execute different programs, one or more of which may include an application that, when executed, causes the programmer tofunction as described herein. Programmers 20 and 22 may include respective user interfaces that receive input from a user (e.g., a clinician or patient 12, respectively). The user interfaces may include components for interaction with a user, such as a keypad and a display. In some examples, the display may be a cathode ray tube (CRT) display, a liquid crystal display (LCD), or light emitting diode (LED) display and the keypad may take the form of an alphanumeric keypad or a reduced set of keys associated with particular functions. Programmers 20 and 22 can, additionally or alternatively, include a peripheral pointing device, e.g., a mouse, via which a user may interact with the user interface. In some examples, the displays may include a touch screen display, and a user may interact with programmers 20 and 22 via the touch screens of the displays. In some examples, the user may also interact with programmers 20 and 22 and / or IMD 14 remotely via a networked computing device. In some examples, one or both of programmers 20 or 22 may communicate with IMD 14 via an intermediate communication device. In some examples, patient programmer 22 or another charging device may be configured to recharge the battery of IMD 14 if the battery is rechargeable. Patient programmer 22 or clinician programmer 20 may be configured to communicate with the charging device. Patient programmer 20, clinician programmer 22, or another device may be configured to transfer information to and / or from IMD 14 with a networked server for sharing of stored data, programming information, etc.

[0040] Clinician programmer 20 facilitates interaction of a clinician with one or more components of system 10. In some examples, the clinician, (e.g., physician, technician, surgeon, electrophysiologist, or other clinician) may interact with clinician programmer 20 to communicate with IMD 14. For example, the clinician may retrieve physiological or diagnostic information from IMD 14 via clinician programmer 20. As another example, the clinician may interact with programmer 20 to program IMD 14, e.g., select values that define electrical stimulation generated and delivered by IMD 14, select other operational parameters of IMD 14, or the like. For example, as described herein, a clinician may select values of any parameters that define stimulation, which pulses to use, polarity of phases or pulses, how to define one or more phases or interphase delays of each pair of pulses, pulse or phase widths, amplitudes, rate of pair of pulses, bursts of pairs of pulses, scheduling of any pairs of pulses, or any other waveform definition and / or scheduling of waveforms related to the delivery of stimulation. As another example, the clinician may use programmer 20 to retrieve information from IMD 14 regarding the performance or integrity of IMD 14 or other components of system 10, such as lead 16 or a power source of IMD 14. In some examples, this information may be presented to the clinician as an alert if a system condition that may affect the efficacy of therapy is detected.

[0041] In some examples, a clinician may use clinician programmer 20 to create stimulation programs for electrical stimulation (generated and delivered by IMD 14) as therapy to treatbladder dysfunction of patient 12. In some examples, the clinician programmer 20 transmits the stimulation programs to IMD 14 for storage in a memory of IMD 14. Clinician programmer 20 may be configured to have additional functionality and / or control of IMD 14 than the patient programmer 22.

[0042] Patient programmer 22 facilitates interaction of patient 12 with one or more components of system 10. In some examples, patient 12 may interact with patient programmer 22 to control IMD 14 to deliver electrical stimulation, to manually abort the delivery of electrical stimulation by IMD 14, or to inhibit the delivery of electrical stimulation by IMD 14. Patient 12 may, for example, use a keypad or touch screen of programmer 22 to cause IMD 14 to deliver electrical stimulation, e.g., to activate one or more stimulation programs, or the like.

[0043] In some examples described herein, patient 12 may provide input to patient programmer 22 indicating that a bladder related event occurred. For example, in some examples, patient 12 may select a particular button of patient programmer 22 to indicate an occurrence of a bladder related event or provide input to a touch screen of patient programmer 22 indicating the occurrence of the bladder related event. The button can be a dedicated button that is designated to receive input from patient 12 indicating the bladder related event, or the button can be a multifunction button, such as a soft key that changes function depending upon the section of the user interface currently viewed by patient 12 (or another user). After receiving the input, patient programmer 22 may store the occurrence of the bladder related event, transmit the indication of the bladder related event to IMD 14, identify a timing of a plurality of bladder related events based on the bladder related event, or the like.

[0044] In other examples, one or more other components of therapy system 10 receives the patient input indicating the bladder related event. For example, in some examples, patient 12 interacts with IMD 14 to provide the input. As an example, IMD 14 can include a motion sensor integrated into or on a housing of IMD 14, where the motion sensor is configured to generate a signal that is indicative of patient 12 tapping IMD 14 through the skin. The number, rate, or pattern of taps may be associated with the different types of input, such as input indicating a bladder related event occurred, input indicating an intent to void, or the like. Patient 12 may provide the input by tapping IMD 14 and processing circuitry of IMD 14 may identify the tapping of IMD 14 by patient 12 to determine when patient input is received and to identify a timing of a plurality of bladder related events based upon receiving the patient input.

[0045] In some examples, it may be desirable to balance the repetitiveness of the therapy with muscle recovery times in order to help prevent muscle fatigue from the stimulation. In some examples, IMD 14 delivers multiple sessions of electrical stimulation daily or over another period of time, multiple cycles of electrical stimulation per session. During each stimulationsession, IMD 14 may generate and deliver stimulation according to predetermined therapy programs, such as each program defining the delivery of a pair of pulses or other stimulation waveform as described herein. In some examples, patient 12 may determine when the delivery of electrical stimulation may be convenient, e.g., not disruptive, not embarrassing, or the like, for patient 12 and may provide input to patient programmer 22 to define the schedule of electrical stimulation delivery to accommodate these times, or provide input to patient programmer 22 that initiates the electrical stimulation delivery accordingly.

[0046] Patient programmer 22 may also receive other input from the patient regarding therapy. For example, patient programmer 22 may receive input from the patient that indicates the current therapy is acceptable (e.g., a “like” button) and / or receive input from the patient that indicates the current therapy is not acceptable (e.g., a “dislike” button). In response to receiving input that the therapy is acceptable, programmer 22, programmer 20, and / or IMD 14 may identify one or more parameters defining the electrical stimulation deliverable at that time as acceptable to the patient. In response to receiving input that the therapy is not acceptable, programmer 22, programmer 20, and / or IMD 14 may identify the stimulation deliverable at that time as unacceptable to the patient. If stimulation is unacceptable, a device of system 10 may adjust one or more parameters defining the stimulation or prompt the user to adjust one or more parameters.

[0047] IMD 14, clinician programmer 20, and patient programmer 22 may communicate via wireless communication using any techniques known in the art. Examples of communication techniques may include, for example, low frequency or radiofrequency (RF) telemetry, or Bluetooth. Other techniques are also contemplated. In some examples, clinician programmer 20 and / or patient programmer 22 may include a programming head that may be placed proximate to the patient’s body near the IMD 14 implant site in order to improve the quality or security of communication between IMD 14 and clinician programmer 20 and / or patient programmer 22.

[0048] As described herein, IMD 14 may be configured to deliver electrical stimulation therapy using a repeating sequence of a pair of pulses, or multiple different pairs of pulses. The processing circuitry that is configured to control stimulation may be included within or distributed between one or more of IMD 14, programmer 20, programmer 22, or other device. In one example, IMD 14 may control stimulation circuitry of IMD 14 to deliver a sequence of the pairs of pulses. Each pair of pulses may be defined by parameters of respective phases of each pulse. IMD 14 may also control the stimulation circuitry to repeatedly deliver the pairs of pulses according to a schedule, such as a continuous rate, bursts of pairs of pulses, or any other sequence of the pairs of pulses of electrical stimulation.

[0049] As described herein, processing circuitry of any device of system 10 (e.g., processing circuitry of IMD 14, programmer 20, and / or programmer 22) can control stimulation circuitry of IMD 14 to generate and deliver a pair of a first pulse and a second pulse. The first pulse may include a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity. The second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity. In this manner, each of the first and second pulses can include two respective phases. In some examples, the second phase of the first pulse has a width that is less than a width of the third phase (e.g., the first phase of the second pulse of the pair). Since the pair of pulses includes two pulses each having two phases, the pair of pulses may be referred to as multi-phase waveform in some examples. The multi-phase waveform may include any number of phases or types of phases as described herein. The processing circuitry can also control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0050] FIG. 2 is a conceptual block diagram illustrating an example of an IMD 14 configured to deliver therapy to a patient. As shown in FIG. 2, a stimulation circuitry 44 (e.g., electrical circuitry that may include a stimulation generator) of IMD 14 may generate electrical stimulation according to a plurality of electrical stimulation parameter sets or therapy programs. IMD 14 may deliver therapy to one or more nerves of patient 12 via one or more electrodes 42A-D (collectively, “electrodes 42”) positioned along lead 40. In some examples, IMD 14 may further include electrical sensing circuitry 46 for sensing a signal generated by one or more of nerves or one or more muscles in response to the electrical stimulation. The same or different electrodes may be used to generate stimulation and detect the response signal. In some examples, different sets of electrodes may be used to deliver stimulation and sense a physiological response to the delivered stimulation. IMD 14 may further include processing circuitry 32 that controls the operations of IMD 14 with the aid of instructions associated with program information that is stored in memory 34. IMD 14 may communicate with an external clinician programmer 20, external patient programmer 22, or another external device via telemetry circuitry 36.

[0051] Processing circuitry 32 may include one or more processors, such as 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. Memory 34 may include memory, 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 instructionsfor causing the one or more processors to perform the actions attributed to them. Further, memory 34 may be implanted entirely in hardware, software, or a combination thereof.

[0052] In some examples, processing circuitry 32 of IMD 14 is configured to deliver pairs of pulses according to a predetermined schedule or in response to one or more trigger events, such as identification of an upcoming bladder related event, a sensed parameter (e.g., bladder pressure or volume) exceeding a threshold, patient request for therapy, or any other type of feedback. In some examples, a sensed parameter may be sensed from nerves, muscles, or other tissue different from the bladder.

[0053] In some examples, IMD 14 may possess one or more electrodes 42 coupled to IMD 14 via one or more leads 40. Electrodes 42 may be configured to deliver electrical stimulation according to a plurality of electrical stimulation parameter sets or therapy programs generated by processing 32 and stored in memory 34. Electrodes 42 may operate as a cathode or an anode. Electrodes 42 may be any type of electrode, such as a ring electrode, segmented electrode, paddle electrode, cuff electrode, needle electrode, or plate electrode. Electrodes 42 are typically implanted electrodes disposed internal of the patient. However, one or more of electrodes 42 may be external to the patient in some examples. In some examples, electrodes 42 may be implanted adjacent to or even coupled to one or more of a patient’s nerve fibers. In some examples, electrode 42 may be implanted adjacent to or even coupled to (e.g., implanted at least partially within) a tissue or muscle fiber. In some examples, more than one electrode may be coupled to the same nerve. In some examples, electrodes 42 may be coupled to a bundle of nerves or muscle fibers. In this manner, one or more electrodes of electrode 42 may be disposed adjacent to, around (e.g., a cuff electrode), or even within a nerve or muscle. Although four electrodes 42 are shown in the example of FIG. 2, fewer than four or more than four electrodes may be carried by lead 40, or multiple leads, in other examples. In some examples, some of electrodes 42 may be positioned to deliver stimulation while other electrodes 42 may be positioned to detect physiological responses from delivered stimulation. In other examples, the same electrodes of electrodes 42 may be configured to deliver stimulation and sense electrical signals. In other examples, the same electrodes that delivered stimulation may be used to detect nerve and / or muscle responses evoked from the delivered stimulation in order to titrate stimulation.

[0054] Each electrical stimulation parameter set or therapy program generated by processing circuitry 32 may define an electrical stimulation signal deliverable to a patient. In some examples, the electrical stimulation parameter set or therapy program may include values for voltage or current amplitude, pulse (or pair of pulses) frequency, pulse width, pulse polarity, phase width, phase polarity, phase amplitude, interphase delay width, active or passive recharge,and / or electrode combination. In some examples, the electrical stimulation parameter set may also define the recharge phase of a pulse, such as amplitude and / or pulse width for active recharge phases or whether the recharge phase is passive. These values of the voltage or current amplitude over time for each pulse may define the waveshape of each phase or signal (e.g., rectangular, sinusoidal, Gaussian, sawtooth, rising, falling, etc.). In addition, each stimulation parameter set may define a burst of pulses and a frequency of the burst of pairs of pulses instead of a continuous pulse train. Different stimulation parameter sets or therapy programs may vary by a different value for at least one of the stimulation parameters. In some examples, the electrical stimulation parameter set or therapy program may include the number of pulses or signals or the duration for which pulses are to be delivered. The electrode combination may define which electrodes are used to deliver stimulation signals and the polarity (cathode or anode) of each electrode (which may change during different phases of each pulse). In some examples, the electrical stimulation parameter set may define electrical stimulation at, or below, a perception threshold (e.g., the level at which the stimulation is perceived by the patient), a motor threshold (e.g., the level at which a muscle response is induced), and / or an activation threshold (e.g., the level at which the nerve is depolarized to activate the nerve) of the patient.

[0055] In one example of the system described herein, processing circuitry 32 may select an electrical stimulation parameter set (e.g., values for respective parameters) or therapy program. For example, IMD 14 may deliver electrical stimulation therapy to the patient via electrodes 42 A and 42B for one pair of pulses and electrodes 42B and 42 for another pair of pulses of a sequence. In other examples, one or more additional or alternative electrodes 42 may be used to deliver the electrical stimulation therapy to the patient. In some examples, electrical sensing circuity 46 of IMD 14 may obtain a signal representative of an electrical response sensed from the patient in response to the electrical stimulation delivered to the patient according to the respective electrical stimulation parameter set or therapy program.

[0056] The electrical response obtained from the patient may be a measured voltage or a measured current from nerves and / or muscles and sensed by electrodes 42. In one example, electrode 42B senses a measured voltage response of a nerve fiber in response to the electrical stimulation delivered to the same nerve fiber according to the respective electrical stimulation parameter set. In another example, electrode 42B senses an electromyogram (EMG) signal of the patient. In another example, electrode 42B senses a nerve recording of an action potential of one or more nerves of the patient. In another example, electrode 42B senses a composite bioelectrical signal corresponding to an activity of nerve and muscle fibers of the patient. In another example, electrode 42B senses a respective movement signal representative of a motion of a portion of the patient in response to the electrical stimulation. In this manner, one or moreelectrodes 42 may be configured to deliver electrical stimulation signals and / or sense evoked responses from tissue. In some examples, the measured response to stimulation may be used by IMD 14 or another device to adjust one or more parameters that defines the pair of pulses and / or schedule of the pair of pulses to be delivered to the patient (e.g., reduce or increase the duty cycle of the sequence).

[0057] Electrical sensing circuitry 46 may receive respective sensed signals from one or more electrodes, such as electrode 42B, evoked from the electrical stimulation delivered according to the electrical stimulation parameter set. In some examples, electrical sensing circuitry 46 may perform signal processing of each received signal to remove noise or other unwanted frequencies or artifacts (e.g. stimulation, motion, cardiac etc.). Electrical sensing circuitry 46 may also convert the analog signal to a digital signal and / or provide other signal processing functionality. Processing circuitry 32 may operate in conjunction with electrical sensing circuitry 46 to evaluate or analyze the received signal for one or more characteristics, such as one or more signal peaks, peak amplitudes, number of peaks, areas under peaks, peak widths, time between peaks, ratios of peak amplitudes, widths, and / or areas, peak latency, signal valleys, valley amplitudes, number of valleys, areas above valleys, valley widths, time between valleys, ratios of valley amplitudes, widths, and / or areas, valley latency, root-mean-square signal value, signal skew, kurtosis, frequency and / or spectral content of the signal(s), or any other suitable signal feature. Using one or more of these characteristics of the sensed signal, processing 32 may determine whether or not the respective parameter set defined effective stimulation or if a different parameter set may be more effective. Once processing circuity 32 determines that a parameter set defined stimulation that evoked a desired response from the patient, processing circuity 32 may update the parameters that define the pairs of pulses that are defined by the parameter set. In some examples, processing circuity 32 may adjust one or more parameters to use the new parameter value identified as being more effective instead of a previous parameter value.

[0058] Additionally, or alternatively, electrical sensing circuitry 46 may be configured to determine a pressure or a volume of a bladder, a physical activity, a time of day, an amount of fluid intake, and / or an amount of caffeine consumed by the patient. This data may be received via sensors from the IMD, programmer, or other device monitoring the patient or via patient input. As one example, electrical sensing circuitry may receive respective sensed signals from one or more electrodes 42, which may be analyzed by processing circuitry 32 to determine the pressure or the volume of the bladder of the patient. In turn, processing circuitry 32 may start and / or stop delivery of therapy using the sequence of pairs of pulses based on the pressure and / or the volume of the bladder. In some examples, processing circuitry 32 may adjust a duty cycle of the sequence of pairs of pulses based on the need for therapy, such as increasing the duty cycle inresponse to determining that the bladder has increased in volume (or exceeded one or more volume or pressure thresholds) and decreasing the duty cycle in response to determining that the bladder has been emptied (e.g., a voiding event occurred).

[0059] The architecture of IMD 14 illustrated in FIG. 2 is shown for exemplary purposes only. The techniques as set forth in this disclosure may be implemented in the example IMD 14 of FIG. 2, as well as other types of IMDs not described specifically herein. For example, processing circuitry 32 may be located within IMD 14, or within an external programming device used to configure or control IMD 14 remotely. Further, electrical sensing circuity 46 may be located within IMD 14, and / or within an external programming device that senses nerve response to electrical stimulation via one or more external electrodes or senses another physiological event of the patient (e.g., a pressure or a volume of a bladder, a physical activity, a time of day, an amount of fluid intake, and / or an amount of caffeine consumed by the patient). In other examples, IMD 14 may include or be in direct communication with other sensors, such as one or more accelerometers, pressure sensors, flow sensors, wetness sensors, or any other sensors that may provide information indicative of bladder or bowel related events of patient 12.

[0060] FIG. 3 is a block diagram illustrating an example patient programmer 22. While patient programmer 22 may generally be described herein as a hand-held computing device, in other examples, patient programmer 22 may be a notebook computer, tablet computer, a cell phone, smart phone, or a workstation, or a remote / key fob for example. As illustrated in FIG. 3, patient programmer 22 may include a processing circuitry 52, memory 54, telemetry circuitry 58, user interface 56, and power source 60. Memory 54 may store program instructions that, when executed by processing circuitry 52, cause processing circuitry 52 and patient programmer 22 to provide the functionality ascribed to patient programmer 22 throughout this disclosure. Clinician programmer 20 may include similar components to patient programmer 22.

[0061] In some examples, memory 54 may further include program information, e.g., stimulation programs similar to those stored in memory 34 of IMD 14. In some examples, the stimulation programs stored in memory 54 may be downloaded into memory 34 of IMD 14. Memory 54 may include any volatile, non-volatile, fixed, removable, magnetic, optical, or electrical media, such as RAM, ROM, CD-ROM, hard disk, removable magnetic disk, memory cards or sticks, NVRAM, EEPROM, flash memory, and the like. Processing circuitry 52 can take the form one or more microprocessors, DSPs, ASICs, FPGAs, programmable logic circuitry, or the like, and the functions attributed to processing circuitry 52 herein may be embodied as hardware, firmware, software or any combination thereof.

[0062] User interface 56 is configured to receive input from a user and may include, for example, a button or keypad, lights, a speaker for voice commands, a display, such as a LCD,LED, or CRT. In some examples, the display may include a touch sensitive screen. In some examples, processing circuitry 52 may receive patient input, e.g., patient input indicating a bladder related event, via user interface 56. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. This patient input may be received by an IMD, programmer, smartphone, or any other device. In response to receiving the input, processing circuitry 52 may, for example, control telemetry circuitry 58 to deliver a signal that indicates receipt of the input to IMD 14, clinician programmer 20, or another device. For clinician programmer 20, a user interface similar to user interface 56 may represent selectable icons, drop down menus, text entry fields, numerical entry fields, or any other input mechanisms for the clinician to select parameter values that define the delivery of the pairs of pulses, schedule of the pairs of pulses, or any other criteria that defines the delivery of the pairs of pulses or multiphase waveform as described herein.

[0063] Processing circuitry 52 may also be configured to present information, e.g., information related to one or more sessions of electrical stimulation, electrical stimulation parameters, schedules of delivery of electrical stimulation, initiation of a particular stimulation session, available parameter variation patterns, parameter variation patterns for pulse trains, pulse trains selected for a sequence, sequence parameters, and the like, to patient 12 or another user (e.g., a patient caretaker) via user interface 56. Although not shown, patient programmer 22 may additionally or alternatively include a data or network interface to another computing device, to facilitate communication with another device, e.g., IMD 14, and presentation of information relating to electrical stimulation via the other device.

[0064] Telemetry circuitry 58 supports wireless communication between IMD 14 and patient programmer 22 under the control of processing circuitry 52. Telemetry circuitry 58 may also be configured to communicate with another computing device, such as clinician programmer 20, via wireless communication techniques, or direct communication through a wired connection.Telemetry circuitry 58 may be substantially similar to telemetry circuitry 36 described above, providing wireless communication via an RF or proximal inductive medium. In some examples, telemetry circuitry 58 may include an antenna, which may take on a variety of forms, such as an internal or external antenna. An external antenna that is coupled to patient programmer 22 may correspond to a programming head that may be placed over IMD 14.

[0065] Examples of local wireless communication techniques that may be employed to facilitate communication between patient programmer 22 and another computing device include RF communication according to the 802.11 or Bluetooth® specification sets, infrared communication, e.g., according to the IrDA standard, or other standard or proprietary telemetryprotocols. In this manner, other external devices may be capable of communicating with patient programmer 22 without needing to establish a secure wireless connection.

[0066] IMD 14, patient programmer 22, and / or clinician programmer 20 may control the delivery of electrical stimulation according to one or more stimulation programs that define the delivery of the pairs of pulses. In some examples, the one or more stimulation programs may also define how the pairs of pulses are delivered, such as the frequency of the pairs of pulses repeating, duty cycle of the pairs of pulses, closed-loop feedback parameters for automatic adjustment of the sequence and / or pairs of pulses, etc. In some examples in which patient programmer 22 controls the stimulation, patient programmer 22 may transmit stimulation programs (e.g., the actual parameter values or an indication of the stimulation program) for implementation by IMD 14 to IMD 14 via telemetry circuitry 58. In some examples, a user (e.g., patient 12 or a clinician) may select one or more stimulation programs from a list provided via a display of user interface 56. Alternatively, patient programmer 22 may transmit a signal to IMD 14 indicating that IMD 14 should execute locally stored programs or therapy schedules. In such a manner, control over the electrical stimulation may be distributed between IMD 14 and patient programmer 22, or may reside in either one alone.

[0067] Power source 60 is configured to deliver operating power to the components of patient programmer 22. Power source 60 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery may be rechargeable to allow extended operation. Recharging may be accomplished by electrically coupling power source 60 to a cradle or plug that is connected to an alternating current (AC) outlet. Additionally, or alternatively, recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within patient programmer 22. In other examples, traditional batteries (e.g., nickel cadmium or lithium ion batteries) may be used. In addition, patient programmer 22 may be directly coupled to an alternating current outlet to power patient programmer 22. Power source 60 may include circuitry to monitor power remaining within a battery. In this manner, user interface 56 may provide a current battery level indicator or low battery level indicator when the battery needs to be replaced or recharged. In some cases, power source 60 may be capable of estimating the remaining time of operation using the current battery.

[0068] In some examples, clinician programmer 20 includes components similar to those of patient programmer 22 shown in FIG. 3. However, other configurations of clinician programmer 20 are contemplated.

[0069] FIG. 4 is a conceptual diagram of an example lead and electrode combinations. As shown in FIG. 4, lead 102 is a medical lead that includes four cylindrical electrodes at differentaxial locations along the length of lead 102. Lead 102 is an example of leads 16 and 14, but other leads may have one, two, three, five, six, or more cylindrical electrodes. In some examples, one or more electrodes may be segmented electrodes that are electrodes located only partially around the perimeter of lead 102. For example, lead 102 may include one or more axial locations along the lead that include one, two, three, four, or more electrodes at the same axial location but at different respective circumferential locations around the housing of lead 102. Each of these electrodes may be independently selected to be a cathode or anode to deliver a stimulation pulse (or each phase of a pulse) and / or sense signals from the patient. In some examples, the housing of IMD 14, for example, may carry one or more electrodes that can sink or source current from or to one or more electrodes of lead 102.

[0070] In the example of FIG. 4A, lead 102 includes four electrodes 104, 106, 108, and 110. These four electrodes may be used as cathodes or anodes in different electrode configurations. Configuration A indicates that electrode 104 is an anode and electrode 110 is a cathode.Configuration B indicates that electrode 104 is an anode and electrode 108 is a cathode.Configuration C indicates that electrode 110 is an anode and electrode 106 is a cathode.Configuration D indicates that electrode 110 is an anode and electrode 104 is a cathode. These are just example electrode configurations A, B, C, and D that are possible using a four electrode lead 102 and will be described below to illustrate possible pairs of pulses for electrical stimulation. For a pulse that includes an anodic phase and cathodic phase, the electrode configuration is reversed to reverse the polarity. However, other electrode configurations are possible, such as electrode 106 being an anode and electrode 108 being a cathode, electrode configurations that include three or four electrodes (e.g., electrode 106 is a cathode and electrodes 104 and 108 are anodes). In some examples, electrode configurations may be provided between two or more electrodes distributed across two or more leads. In some examples, electrode configurations may be provided between one or more electrode as the cathodes and the IMD 14 as the anode. Therefore, the electrode configurations A, B, C, and D of FIG. 4A are merely examples of some different electrode configurations that are possible for delivery of pairs of pulses as described herein.

[0071] FIG. 5 is a timing diagram of an example stimulation waveform 200 according to examples of this disclosure. As shown in the example of FIG. 5, waveform 200 is an example of a repeatable pair of pulses that can be delivered at any desired schedule (e.g., a continuous rate, bursts of the waveform, or other predetermined pattern). Processing circuitry 32 can control stimulation circuitry 44 to deliver waveform 200 according to stored instructions in memory 34, for example.

[0072] Stimulation waveform 200 is shown as a trace 202 of current amplitude over time. Positive current amplitude may refer to anodic polarity and negative current amplitude may refer to cathodic polarity in this example, but alternative configurations are contemplated. Stimulation waveform 200 is shown as including two pairs of pulses: pulse 204 followed by pulse 210. Each pulse 204 and pulse 210 includes two phases. However, in other examples, three or more pulses may be used in waveform 200. In some examples, one or more of the pulses may include only one phase, or three or more phases. Although stimulation waveform 200 is described as a pair of pulses having multiple phases, waveform 200 may be described has a multi-phase waveform with several phases in other examples instead of defining groups of phases into respective pulses. In some examples, each phase may be referred to as respective pulses. In any case, waveform 200 may include a pattern of anodic and cathodic current that is configured to provide additional charge that can selectively activate or target certain nerve fibers.

[0073] In the example of FIG. 5, stimulation waveform 200 includes a first pulse 204 that includes respective first phase 204 A and second phase 204B. Phase 204 A may be an anodic pulse (or anodic polarity) and phase 210B may be a cathodic pulse (or cathodic polarity). Phase 204A is delivered for duration A, and phase 204B is delivered for duration C. Interphase delay 206 may be delivered for duration B to separate phases 204A and 204B, but interphase delay 206 may not be included in some examples. Interphase delay 208 may separate pulses 204 and 210, and separate phase 204B from phase 210A. Interphase delay 208 may be provided during duration D. Each interphase delay described herein may refer to a period of time where IMD 14 does not deliver current to or from tissue, as represented as a zero amplitude in waveform 200. In practice, the interphase delay may be close to zero, but some current may be delivered due to variation in system tolerances.

[0074] After interphase delay 208, waveform 200 includes second pulse 210. Pulse 210 includes third and fourth phases 210A and 210B. Phase 210A may be a cathodic phase (or cathodic polarity) which is the same as phase 204B of pulse 204. Phase 210A may be delivered for duration E. Phase 210B may be an anodic phase (or anodic polarity) and be delivered for duration G. Interphase delay 212 may separate phases 210A and 210B for a duration F. In some examples, pulse 210 may not include interphase delay 212. Together, pulses 204 and 210, and interphase delay 208 in some examples, may be referred to as a pair of pulses as described herein. Each duration of a phase may be referred to as a width, or pulse width, of the delivered current in some examples.

[0075] As shown in the example of FIG. 5, phase 204 A can be delivered at a desired amplitude generally between 0.01 milliamps (mA) and 1 mA. The amplitude of phase 204 may be fixed in some examples, but may be adjustable in other examples. In one example, theamplitude of phase 204 A may be 0.1 mA. Duration A of phase 204 A may have a width in the range of 0.5 to 1.5 milliseconds (ms), such as 1.0 ms in one example. In some examples, phase 204A may be referred to as a “pre-pulse” or initial charge balancing phase before phases 204B and 210A can be delivered.

[0076] Generally, phases 204B and 210A have the same polarity which can inject the desired charge to tissue. Phase 204B can have an amplitude that is adjustable for the patient. The amplitudes of phase 204B and 210A may be tied together, such as using a ratio (e.g., an amplitude ratio) that is maintained, a maintained amplitude differential, or a combination thereof. In some examples, the ratio of phase 204B amplitude to phase 210A amplitude may be in a range of 2:1 to 10:1. In one example, the ratio of phase 204B amplitude to phase 21 OA amplitude is 5:1. However, higher or lower ratios may be used in other examples. In some examples, the charge delivered from each of phases 204B and 210A may be maintained in a ratio or some other predetermined relationship, such that the charge takes into account the amplitude and width of each phase. In some examples, the charge ratio may be 1 : 1. In other examples, the charge of phase 204B to the charge of phase 210A may be in a range of 1:5 to 5:1. However, other charge ratios may be used in other examples. The amplitude of phase 204B may be set to any desired amplitude, which may be set according to patient response. For example, the amplitude of phase 204B may be set to an amplitude that is at the discomfort threshold of the patient or slightly below. In other examples, the amplitude of phase 204B may be set to an amplitude between the sensory threshold and discomfort threshold. This amplitude may be set as desired by the patient and / or adjusted over time to customize therapy as needed.

[0077] Duration C of phase 204B may be in a range of 60 microseconds to 250 microseconds, such as 200 microseconds in some examples. Interphase delay 208 may have a duration D that lasts in a range of 10 microseconds to 1 ms or longer, and may be adjusted as appropriate given the duration of other phases and pulses of waveform 200.

[0078] Phase 204B typically has a width less than the width of phase 210A. For example, duration E of phase 210A of pulse 210 may be in a rage of 500 microseconds to 5 ms or longer, or in a range of 1 ms to 3 ms in another example. In one example, duration E of phase 210A is at least 1 ms. In one example, duration E of phase 210 A is approximately 1 ms. In some examples, the durations A, B, C, and D may be set to add up to a target duration after onset of phase 204A. This target duration may be in a range of 1 ms to 3 ms in some examples, or approximately 2 ms in one example. Phase 210B may be referred to as a recharge phase in some examples in order to balance charge to the tissue after deliver of phase 210A. Phase 210B may be an active recharge phase (e.g., delivery of a pulse of current) or a passive recharge phase as shown (e.g., where switches are closed to allow excess charge at the tissue to return from tissueand back to IMD 14. In the passive recharge phase, the amplitude of current may have an exponential decay or other curve instead of a rectangular pulse of an active recharge. Duration G of phase 21 OB may be set as long as needed during passive recharge in order to balance charge without impinging on the next pulse to be delivered. For an active recharge phase, duration G may be set to a width needed to deliver opposing charge that can balance the charge delivered to the tissue using phases 204B and 21 OB.

[0079] Each interphase delay may be set as needed, or perhaps not included in some examples. As shown in the example of FIG. 5, interphase delay 206 may have a duration B in a range of at least 10 microseconds in some examples, or in a range selected from 10 microseconds to 100 microseconds in other examples. In one example, duration B may be approximately 20 microseconds. Interphase delay 212 between phases 210A and 210B may have a duration F in a range of at least 10 microseconds in some examples, or in a range selected from 10 microseconds to 100 microseconds in other examples. In one example, duration F may be approximately 10 microseconds. Interphase delay 212 may be optional and not included in some waveforms of pairs of pulses.

[0080] In some examples, any of the durations of various phases or interphase delays may be user-adjustable via a user interface and / or automatically adjustable based on user or sensed feedback. In some examples, one duration may be changed independently without affecting other durations of any other phases, pulses, or interphase delays. In other examples, the adjustment of one duration may cause the system to adjust one or more other durations in order to maintain a ratio or total duration between those specific phases or delays, and / or to maintain a total length of the pair of pulses. For example, to maintain a total length of the pair of pulses, increasing the duration of phase 204A may cause the system to reduce the duration of interphase delay 208. However, such a relationship may apply to any other combination of phases, pulses, and / or interphase delays.

[0081] IMD 14 may be configured to deliver the stimulation by repeating waveform 200 over time. In some examples, IMD 14 may be configured to continuously deliver the waveform 200 at a certain rate. Waveform 200 may be configured to be delivered at a rate in a range of 4 Hz to 400 Hz, for example. In other examples, waveform 200 may be delivered at a rate in a range of 8 Hz to 60 Hz or 8 Hz to 40 Hz. In another example, waveform 200 may be delivered at a rate in a range of 8 Hz to 20 Hz. In one example, waveform 200 may be delivered at a range of approximately 14 Hz. This rate may refer to the rate that the pair of pulses is delivered, not each individual pulse or phase.

[0082] Instead of continuous delivery of waveform 200, IMD 14 may be configured to deliver waveform 200 in bursts that have longer inter-burst durations than the duration betweeneach waveform 200 within each burst (e.g., intra-burst duration). In other examples, waveform 200 may be repeatedly delivered according to a non-uniform pattern that makes up a schedule of waveforms (or pairs of pulses). The schedule may also be repeated over time for delivery of stimulation therapy. In some examples, waveform 200 may be cycled, or turned on and off, as needed to provide therapy to the patient. On periods for each cycle may be in a range of seconds, hours, or even days or weeks. Off periods for each cycle may be in a range of seconds, hours, or even days or weeks in some examples. In one example, the on period may be 15 minutes and the off period may be 45 minutes. In some examples, the on periods may be much shorter than the off periods. Tibial nerve stimulation therapy may be efficacious using on periods of less 30 minutes or less and off periods that last 10-30 days.

[0083] In some examples, waveform 200 may be delivered as part of an overall therapy strategy with tonic, or continuous, stimulation of repeating pulses. For example, IMD 14 may be configured to deliver tonic stimulation as a baseline therapy. IMD 14 may cycle the tonic therapy on and off as need when less therapy is needed. IMD 14 may switch to continuous, or cycled, repeated delivery of waveform 200 to provide increased stimulation dosage for the patient periodically or as needed. In this manner, IMD 14 may switch between tonic stimulation and waveform 200 (e.g., repeating pairs of pulses) over time which may improve therapy and / or reduce the likelihood of habituation.

[0084] In some examples, processing circuitry 32 may be configured to control stimulation circuitry 44 to repeatedly deliver waveform 200 (e.g., a pair of pulses) to at least one of a sacral nerve or a tibial nerve in order to provide incontinence therapy. However, waveform 200, or any other repeating pair of pulses as described herein, may be configured to be provided to other nerves or tissues as may be appropriate to provide efficacious therapy to the patient.

[0085] Waveform 200 may be altered in some examples while still retaining some benefits for the patient. For example, phase 204 A may be reduced in amplitude or duration, or even removed completely. In another example, phase 204 A may be split into multiple consecutive phases of the same polarity. In some examples, other waveforms may include variations to phase 210A. These variations may include adding additional consecutive phases 210A of the same polarity or splitting phase 210A into shorter consecutive phases of the same polarity. Repeatedly delivering consecutive phases of the same polarity may result in excess charge at the electrodes. Some materials may provide improved resistance to degradation in these situations, such as carbon electrodes, electrodes including textured titanium, or other surfaces that can included increased surface areas.

[0086] All of the phases of waveform 200 are shown as rectangular phases or pulses where current is increased or decreased nearly simultaneously. In other examples, one or more phasesmay have sloped or ramped beginning and / or ends of each phase. Ramping of one or more phases may reduce the likelihood of perception by the patient. In some examples, the ramp duration may be limited to a duration that is less than half of the width of that phase, for example. In some examples, relatively longer phases, such as phase 204 A and phase 210A may be ramped, but shorter phases such as phase 204B may not be ramped.

[0087] FIG. 6 is a graph 300 of bladder holding volumes for different example stimulation waveforms. As shown in graph 300, three different conditions were evaluated to illustrate the benefits of repeating a pair of pulses described herein, such as waveform 200. The data shown in FIG. 6 was obtained during cystometry in which a catheter is used to add fluid to the bladder. The maximum bladder holding volume for the baseline, or when no stimulation was delivered, is lower than the maximum bladder holding volume of tonic stimulation. However, the “Pair of Pulses” data shows that the pair of pulses used for stimulation provided an increased maximum bladder holding capability over tonic stimulation. In this manner, a patient receiving the pair of pulses can achieve greater incontinence relief than tonic stimulation.

[0088] FIG. 7 is a graph 320 of EMG amplitude growth curves from detected data for different stimulation waveforms. The EMG signals were measured from the pelvic floor to obtain the data of graph 320. As shown in the example of FIG. 7, tonic stimulation data 322 indicates that for almost all stimulation current amplitudes, tonic stimulation resulted in much less amplitude of EMG signals. Indeed pair of pulses stimulation data 324 indicates that the resulting EMG amplitudes were relatively high. This higher EMG amplitude may indicate greater nerve modulation from the repeating pairs of pulses than tonic stimulation.

[0089] FIG. 8 includes graphs of example EMG signals for different stimulation waveforms. As shown in FIG. 8, graphs 340 and 342 show raw and filtered EMG data for tonic stimulation, respectively. Similarly, graphs 344 and 346 show raw and filtered EMG data for pairs of pulses stimulation, respectively. The detected EMG signals were in the range of 20-80Hz. Graph 346 shows that the pairs of pulses provided much greater EMG activity (greater than 3,000 microvolts) than that of tonic stimulation (less than 100 microvolts) shown in graph 342. In addition, in this example, the shape of the EMGs in graphs 346 and 342 are different leading to a correlation coefficient between tonic stimulation and pairs of pulses was only 0.19 (e.g., low correlation). This lack of correlation between tonic stimulation and pairs of pulses stimulation indicates that different muscle groups are being activated by each stimulation.

[0090] FIG. 9 is a flow diagram illustrating an example technique for delivering electrical stimulation including a repeating pair of pulses in accordance with examples of this disclosure. The technique of FIG. 9 will be described with respect to processing circuitry 32 of IMD 14 within system 10 of FIG. 1. In other examples, however, the technique of FIG. 9 may be usedwith other devices within system 10 or a system other than system 10 of FIG. 1, such as by patient programmer 22 or a networked server (e.g., could computing system) or other device and / or system. In other examples, an external neurostimulator may perform the functions of FIG.9 instead of an implantable device such as IMD 14.

[0091] As shown in the example of FIG. 9, processing circuitry 32 of IMD 14 receives stimulation parameters defining electrical stimulation therapy (400). Processing circuitry 32 may receive these stimulation parameters (and values of each parameter) from a programmer or internal memory. These parameters may be part of a therapy program or other set of instructions that define a waveform described herein, such as a repeating pair of pulses according to a schedule. Processing circuitry 32 can then control stimulation circuitry 44 to deliver a pair of pulses repeatedly according to a schedule (402). As described herein, the pair of pulses may be similar to waveform 200 or another multi-phase waveform. The pair of pulses may be repeated at a continuous, and constant rate that may or may not be cycled on and off, as bursts of pairs of pulses where an inter-burst delay is longer than an intra-burst delay, or a non-uniform predetermined pattern of pairs of pulses.

[0092] If processing circuitry 32 does not receive a command to stop stimulation (“NO” branch of block 404), processing circuitry 32 can continue to control stimulation circuitry 44 to deliver the pair of pulses repeatedly according to the schedule (402). If processing circuitry 32 does receive a command to stop stimulation (“YES” branch of block 404), processing circuitry 32 can control stimulation circuitry 44 to terminate stimulation delivery (406). The command to stop stimulation may be in the form of sensed feedback or timer that may or may not later indicate when to begin stimulation again. In some examples, the command may be a user input request to stop stimulation or other type of input.

[0093] The following examples are described herein.

[0094] Example 1. A system comprising: processing circuitry configured to: control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; and control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0095] Example 2. The system of example 1, wherein the second phase has a second amplitude larger than a third amplitude of the third phase.

[0096] Example 3. The system of any of examples 1 or 2, wherein the processing circuitry is configured to adjust a second amplitude of the second phase and a third amplitude of the third phase to maintain an amplitude ratio of the second amplitude to the third amplitude.

[0097] Example 4. The system of any of examples 1 through 3, wherein the second width has a duration selected from 60 microseconds to 250 microseconds.

[0098] Example 5. The system of any of examples 1 through 4, wherein the third width has a duration of at least 1 millisecond.

[0099] Example 6. The system of any of examples 1 through 5, wherein the fourth phase comprises a passive recharge phase.

[0100] Example 7. The system of any of examples 1 through 6, wherein the first polarity is an anodic polarity, and wherein the second polarity is a cathodic polarity.

[0101] Example 8. The system of any of examples 1 through 7, wherein the pair comprises a first interphase separating the first phase and the second phase, and wherein the first interphase has a duration selected from 10 microseconds to 100 microseconds.

[0102] Example 9. The system of any of examples 1 through 8. wherein the pair comprises a second interphase separating the second phase and the third phase.

[0103] Example 10. The system of any of examples 1 through 9, wherein the pair comprises a third interphase separating the third phase and the fourth phase.

[0104] Example 11. The system of any of examples 1 through 10, wherein the processing circuitry is configured to control the stimulation circuitry to repeatedly deliver the pair at a frequency from 8 Hz to 40 Hz.

[0105] Example 12. The system of any of examples 1 through 11, wherein the processing circuitry is configured to control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse to at least one of a sacral nerve, a tibial nerve, a pudendal nerve, or a bulbospongiosus muscle, and wherein the pair of the first pulse and the second pulse configured to provide incontinence therapy.

[0106] Example 13. The system of example 1, further comprising an implantable medical device comprising the processing circuitry and the stimulation circuitry.

[0107] Example 14. A method comprising: controlling, by processing circuitry, stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; and controlling, by the processing circuitry, the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0108] Example 15. The method of example 14, wherein the second phase has a second amplitude larger than a third amplitude of the third phase.

[0109] Example 16. The method of any of examples 14 or 15, further comprising adjusting a second amplitude of the second phase and a third amplitude of the third phase to maintain an amplitude ratio of the second amplitude to the third amplitude.

[0110] Example 17. The method of any of examples 14 through 16, wherein the second width has a duration selected from 60 microseconds to 250 microseconds, and wherein the third width has a duration of at least 1 millisecond.

[0111] Example 18. The method of any of examples 14 through 17, wherein the first polarity is an anodic polarity, and wherein the second polarity is a cathodic polarity.

[0112] Example 19. The method of any of examples 14 through 18, wherein controlling the stimulation circuitry to repeatedly deliver the pair comprises: controlling the stimulation circuitry to repeatedly deliver the pair at a frequency from 8 Hz to 40 Hz; and controlling the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse to at least one of a sacral nerve, a tibial nerve, a pudendal nerve, or a bulbospongiosus muscle, the pair of the first pulse and the second pulse configured to provide incontinence therapy.

[0113] Example 20. A non-transitory computer readable storage medium comprising instructions that, when executed, causes processing circuitry to: control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; and control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

[0114] The techniques described in this disclosure, including those attributed to system 10, IMD 14, patient programmer 22, and clinician programmer 20, and various constituent components, may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the techniques may be implemented within one or more processors or processing circuitry, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, remote servers, cloud servers, remote client devices, or other devices. 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.

[0115] Such hardware, software, firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. Inaddition, 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.

[0116] The techniques or processes described in this disclosure may also be embodied or encoded in an article of manufacture including a computer-readable storage medium encoded with instructions. Instructions embedded or encoded in an article of manufacture including a computer-readable storage medium encoded, may cause one or more programmable processors, or other processors, to implement one or more of the techniques described herein, such as when instructions included or encoded in the computer-readable storage medium are executed by the one or more processors. Example computer-readable storage media may include random access memory (RAM), ferroelectric random access memory (FRAM), 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 compact disc ROM (CD-ROM), a floppy disk, a cassette, magnetic media, optical media, or any other computer readable storage devices or tangible computer readable media. The computer-readable storage medium may also be referred to as storage devices. In some examples, a computer-readable storage medium comprises non-transitory medium. The term “non-transitory” may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in RAM or cache).

[0117] Various examples have been described herein. Any combination of the described operations or functions is contemplated. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A system comprising:processing circuitry configured to:control stimulation circuitry to deliver a pair of a first pulse and a second pulse, wherein the first pulse comprises a first phase of a first polarity followed by a second phase of a second polarity opposite the first polarity, wherein the second pulse comprises a third phase of the second polarity followed by a fourth phase of the first polarity, and wherein the second phase has a second width less than a third width of the third phase; andcontrol the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse.

2. The system of claim 1, wherein the second phase has a second amplitude larger than a third amplitude of the third phase.

3. The system of any of claims 1 or 2, wherein the processing circuitry is configured to adjust a second amplitude of the second phase and a third amplitude of the third phase to maintain an amplitude ratio of the second amplitude to the third amplitude.

4. The system of any of claims 1 through 3, wherein the second width has a duration selected from 60 microseconds to 250 microseconds.

5. The system of any of claims 1 through 4, wherein the third width has a duration of at least 1 millisecond.

6. The system of any of claims 1 through 5, wherein the fourth phase comprises a passive recharge phase.

7. The system of any of claims 1 through 6, wherein the first polarity is an anodic polarity, and wherein the second polarity is a cathodic polarity.

8. The system of any of claims 1 through 7, wherein the pair comprises a first interphase separating the first phase and the second phase, and wherein the first interphase has a duration selected from 10 microseconds to 100 microseconds.

9. The system of any of claims 1 through 8, wherein the pair comprises a second interphase separating the second phase and the third phase.

10. The system of any of claims 1 through 9, wherein the pair comprises a third interphase separating the third phase and the fourth phase.

11. The system of any of claims 1 through 10, wherein the processing circuitry is configured to control the stimulation circuitry to repeatedly deliver the pair at a frequency from 8 Hz to 40 Hz.

12. The system of any of claims 1 through 11, wherein the processing circuitry is configured to control the stimulation circuitry to repeatedly deliver the pair of the first pulse and the second pulse to at least one of a sacral nerve, a tibial nerve, a pudendal nerve, or a bulbospongiosus muscle, and wherein the pair of the first pulse and the second pulse configured to provide incontinence therapy.

13. The system of claim 1, further comprising an implantable medical device comprising the processing circuitry and the stimulation circuitry.

14. A non-transitory computer readable storage medium comprising instructions that, when executed, causes the processing circuitry to perform the function of any of claims 1 through 13.

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