Patent Description:
Implantable neurostimulator devices are devices that generate and deliver electrical stimuli to body nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc..

<CIT> discloses a system for managing pain of patient using an implantable neuromodulator device, which has a pain analyzer circuit coupled to sensor circuit and is generating a pain score using signal metrics, and with an output unit for outputting pain score to user or process. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in <CIT>. However, the present invention may find applicability with any implantable neurostimulator device system.

An SCS system typically includes an Implantable Pulse Generator (IPG) <NUM> shown in <FIG>. The IPG <NUM> includes a biocompatible device case <NUM> that holds the circuitry and battery <NUM> necessary for the IPG to function. The IPG <NUM> is coupled to electrodes <NUM> via one or more electrode leads <NUM> that form an electrode array <NUM>. The electrodes <NUM> are configured to contact a patient's tissue and are carried on a flexible body <NUM>, which also houses the individual lead wires <NUM> coupled to each electrode <NUM>. The lead wires <NUM> are also coupled to proximal contacts <NUM>, which are insertable into lead connectors <NUM> fixed in a header <NUM> on the IPG <NUM>, which header can comprise an epoxy for example. Once inserted, the proximal contacts <NUM> connect to header contacts within the lead connectors <NUM>, which are in turn coupled by feedthrough pins through a case feedthrough to circuitry within the case <NUM>, although these details aren't shown.

In the illustrated IPG <NUM>, there are sixteen lead electrodes (E1-E16) split between two leads <NUM>, with the header <NUM> containing a 2x1 array of lead connectors <NUM>. However, the number of leads and electrodes in an IPG is application specific and therefore can vary. The conductive case <NUM> can also comprise an electrode (Ec). In a SCS application, the electrode leads <NUM> are typically implanted proximate to the dura in a patient's spinal column on the right and left sides of the spinal cord midline. The proximal electrodes <NUM> are tunneled through the patient's tissue to a distant location such as the buttocks where the IPG case <NUM> is implanted, at which point they are coupled to the lead connectors <NUM>. In other IPG examples designed for implantation directly at a site requiring stimulation, the IPG can be lead-less, having electrodes <NUM> instead appearing on the body of the IPG for contacting the patient's tissue. The IPG leads <NUM> can be integrated with and permanently connected the case <NUM> in other IPG solutions. The goal of SCS therapy is to provide electrical stimulation from the electrodes <NUM> to alleviate a patient's symptoms, most notably chronic back pain.

IPG <NUM> can include an antenna 26a allowing it to communicate bi-directionally with a number of external devices, as shown in <FIG>. The antenna 26a as depicted in <FIG> is shown as a conductive coil within the case <NUM>, although the coil antenna 26a can also appear in the header <NUM>. When antenna 26a is configured as a coil, communication with external devices preferably occurs using near-field magnetic induction. IPG may also include a RadioFrequency (RF) antenna 26b. In <FIG>, RF antenna 26b is shown within the header <NUM>, but it may also be within the case <NUM>. RF antenna 26b may comprise a patch, slot, or wire, and may operate as a monopole or dipole. RF antenna 26b preferably communicates using far-field electromagnetic waves. RF antenna 26b may operate in accordance with any number of known RF communication standards, such as Bluetooth, Zigbee, WiFi, MICS, and the like.

Stimulation in IPG <NUM> is typically provided by pulses, as shown in <FIG>. Stimulation parameters typically include the amplitude of the pulses (A; whether current or voltage); the frequency (F) and pulse width (PW) of the pulses; the electrodes <NUM> (E) activated to provide such stimulation; and the polarity (P) of such active electrodes, i.e., whether active electrodes are to act as anodes (that source current to the tissue) or cathodes (that sink current from the tissue). These stimulation parameters taken together comprise a stimulation program that the IPG <NUM> can execute to provide therapeutic stimulation to a patient.

In the example of <FIG>, electrode E5 has been selected as an anode, and thus provides pulses which source a positive current of amplitude +A to the tissue. Electrode E4 has been selected as a cathode, and thus provides pulses which sink a corresponding negative current of amplitude -A from the tissue. This is an example of bipolar stimulation, in which only two lead-based electrodes are used to provide stimulation to the tissue (one anode, one cathode). However, more than one electrode may act as an anode at a given time, and more than one electrode may act as a cathode at a given time (e.g., tripole stimulation, quadripole stimulation, etc.).

The pulses as shown in <FIG> are biphasic, comprising a first phase 30a, followed quickly thereafter by a second phase 30b of opposite polarity. As is known, use of a biphasic pulse is useful in active charge recovery. For example, each electrodes' current path to the tissue may include a serially-connected DC-blocking capacitor, see, e.g., <CIT>, which will charge during the first phase 30a and discharged (be recovered) during the second phase 30b. In the example shown, the first and second phases 30a and 30b have the same duration and amplitude (although opposite polarities), which ensures the same amount of charge during both phases. However, the second phase 30b may also be charged balance with the first phase 30a if the integral of the amplitude and durations of the two phases are equal in magnitude, as is well known. The width of each pulse, PW, is defined here as the duration of first pulse phase 30a, although pulse width could also refer to the total duration of the first and second pulse phases 30a and 30b as well. Note that an interphase period (IP) during which no stimulation is provided may be provided between the two phases 30a and 30b.

IPG <NUM> includes stimulation circuitry <NUM> that can be programmed to produce the stimulation pulses at the electrodes as defined by the stimulation program. Thus, the IPG <NUM> acts as a power supply to deliver power to the electrodes for providing stimulation to the patient. Stimulation circuitry <NUM> can for example comprise the circuitry described in <CIT> and <CIT>, or described in USPs <CIT> and <CIT>.

<FIG> shows an external trial stimulation environment that may precede implantation of an IPG <NUM> in a patient. During external trial stimulation, stimulation can be tried on a prospective implant patient without going so far as to implant the IPG <NUM>. Instead, one or more trial leads <NUM>' are implanted in the patient's tissue <NUM> at a target location <NUM>, such as within the spinal column as explained earlier. The proximal ends of the trial lead(s) <NUM>' exit an incision <NUM> and are connected to an External Trial Stimulator (ETS) <NUM>. The ETS <NUM> generally mimics operation of the IPG <NUM>, and thus can provide stimulation pulses to the patient's tissue as explained above. See, e.g., <NUM>,<NUM>,<NUM>, disclosing a design for an ETS. The ETS <NUM> is generally worn externally by the patient for a short while (e.g., two weeks), which allows the patient and his clinician to experiment with different stimulation parameters to try and find a stimulation program that alleviates the patient's symptoms (e.g., pain). If external trial stimulation proves successful, trial lead(s) <NUM>' are explanted, and a full IPG <NUM> and lead(s) <NUM> are implanted as described above; if unsuccessful, the trial lead(s) <NUM>' are simply explanted.

Like the IPG <NUM>, the ETS <NUM> can include one or more antennas to enable bi-directional communications with external devices, explained further with respect to <FIG>. Such antennas can include a near-field magnetic-induction coil antenna 42a, and/or a far-field RF antenna 42b, as described earlier. ETS <NUM> may also include stimulation circuitry <NUM> able to form the stimulation pulses in accordance with a stimulation program, which circuitry may be similar to or comprise the same stimulation circuitry <NUM> present in the IPG <NUM>. ETS <NUM> may also include a battery (not shown) for operational power.

<FIG> shows various external devices that can wirelessly communicate data with the IPG <NUM> and the ETS <NUM>, including a patient, hand-held external controller <NUM>, and a clinician programmer <NUM>. Both of devices <NUM> and <NUM> can be used to send a stimulation program to the IPG <NUM> or ETS <NUM>-that is, to program their stimulation circuitries <NUM> and <NUM> to produce pulses with a desired shape and timing described earlier. Both devices <NUM> and <NUM> may also be used to adjust one or more stimulation parameters of a stimulation program that the IPG <NUM> or ETS <NUM> is currently executing. Devices <NUM> and <NUM> may also receive information from the IPG <NUM> or ETS <NUM>, such as various status information, etc..

External controller <NUM> can be as described in <CIT> for example, and may comprise either a dedicated controller configured to work with the IPG <NUM>. External controller <NUM> may also comprise a general purpose mobile electronics device such as a mobile phone which has been programmed with a Medical Device Application (MDA) allowing it to work as a wireless controller for the IPG <NUM> or ETS <NUM>, as described in <CIT>. External controller <NUM> includes a user interface, including means for entering commands (e.g., buttons or icons) and a display <NUM>. The external controller <NUM>'s user interface enables a patient to adjust stimulation parameters, although it may have limited functionality when compared to the more-powerful clinician programmer <NUM>, described shortly.

The external controller <NUM> can have one or more antennas capable of communicating with the IPG <NUM> and ETS <NUM>. For example, the external controller <NUM> can have a near-field magnetic-induction coil antenna 47a capable of wirelessly communicating with the coil antenna 26a or 42a in the IPG <NUM> or ETS <NUM>. The external controller <NUM> can also have a far-field RF antenna 47b capable of wirelessly communicating with the RF antenna 26b or 42b in the IPG <NUM> or ETS <NUM>.

The external controller <NUM> can also have control circuitry <NUM> such as a microprocessor, microcomputer, an FPGA, other digital logic structures, etc., which is capable of executing instructions an electronic device. Control circuitry <NUM> can for example receive patient adjustments to stimulation parameters, and create a stimulation program to be wirelessly transmitted to the IPG <NUM> or ETS <NUM>.

Clinician programmer <NUM> is described further in <CIT>, and is only briefly explained here. The clinician programmer <NUM> can comprise a computing device <NUM>, such as a desktop, laptop, or notebook computer, a tablet, a mobile smart phone, a Personal Data Assistant (PDA)-type mobile computing device, etc. In <FIG>, computing device <NUM> is shown as a laptop computer that includes typical computer user interface means such as a screen <NUM>, a mouse, a keyboard, speakers, a stylus, a printer, etc., not all of which are shown for convenience. Also shown in <FIG> are accessory devices for the clinician programmer <NUM> that are usually specific to its operation as a stimulation controller, such as a communication "wand" <NUM>, and a joystick <NUM>, which are coupleable to suitable ports on the computing device <NUM>, such as USB ports <NUM> for example.

The antenna used in the clinician programmer <NUM> to communicate with the IPG <NUM> or ETS <NUM> can depend on the type of antennas included in those devices. If the patient's IPG <NUM> or ETS <NUM> includes a coil antenna 26a or 42a, wand <NUM> can likewise include a coil antenna 56a to establish near-filed magnetic-induction communications at small distances. In this instance, the wand <NUM> may be affixed in close proximity to the patient, such as by placing the wand <NUM> in a belt or holster wearable by the patient and proximate to the patient's IPG <NUM> or ETS <NUM>.

If the IPG <NUM> or ETS <NUM> includes an RF antenna 26b or 42b, the wand <NUM>, the computing device <NUM>, or both, can likewise include an RF antenna 56b to establish communication with the IPG <NUM> or ETS <NUM> at larger distances. (Wand <NUM> may not be necessary in this circumstance). The clinician programmer <NUM> can also establish communication with other devices and networks, such as the Internet, either wirelessly or via a wired link provided at an Ethernet or network port.

To program stimulation programs or parameters for the IPG <NUM> or ETS <NUM>, the clinician interfaces with a clinician programmer graphical user interface (GUI) <NUM> provided on the display <NUM> of the computing device <NUM>. As one skilled in the art understands, the GUI <NUM> can be rendered by execution of clinician programmer software <NUM> on the computing device <NUM>, which software may be stored in the device's non-volatile memory <NUM>. One skilled in the art will additionally recognize that execution of the clinician programmer software <NUM> in the computing device <NUM> can be facilitated by control circuitry <NUM> such as a microprocessor, microcomputer, an FPGA, other digital logic structures, etc., which is capable of executing programs in a computing device. Such control circuitry <NUM>, in addition to executing the clinician programmer software <NUM> and rendering the GUI <NUM>, can also enable communications via antennas 56a or 56b to communicate stimulation parameters chosen through the GUI <NUM> to the patient's IPG <NUM>.

A portion of the GUI <NUM> is shown in one example in <FIG>. One skilled in the art will understand that the particulars of the GUI <NUM> will depend on where clinician programmer software <NUM> is in its execution, which will depend on the GUI selections the clinician has made. <FIG> shows the GUI <NUM> at a point allowing for the setting of stimulation parameters for the patient and for their storage as a stimulation program. To the left a program interface <NUM> is shown, which as explained further in the '<NUM> Publication allows for naming, loading and saving of stimulation programs for the patient. Shown to the right is a stimulation parameters interface <NUM>, in which specific stimulation parameters (A, D, F, E, P) can be defined for a stimulation program. Values for stimulation parameters relating to the shape of the waveform (A; in this example, current), pulse width (PW), and frequency (F) are shown in a waveform parameter interface <NUM>, including buttons the clinician can use to increase or decrease these values.

Stimulation parameters relating to the electrodes <NUM> (the electrodes E activated and their polarities P), are made adjustable in an electrode parameter interface <NUM>. Electrode stimulation parameters are also visible and can be manipulated in a leads interface <NUM> that displays the leads <NUM> (or <NUM>') in generally their proper position with respect to each other, for example, on the left and right sides of the spinal column. A cursor <NUM> (or other selection means such as a mouse pointer) can be used to select a particular electrode in the leads interface <NUM>. Buttons in the electrode parameter interface <NUM> allow the selected electrode (including the case electrode, Ec) to be designated as an anode, a cathode, or off. The electrode parameter interface <NUM> further allows the relative strength of anodic or cathodic current of the selected electrode to be specified in terms of a percentage, X. This is particularly useful if more than one electrode is to act as an anode or cathode at a given time, as explained in the '<NUM> Publication. In accordance with the example waveforms shown in <FIG>, as shown in the leads interface <NUM>, electrode E5 has been selected as the only anode to source current, and this electrode receives X = <NUM>% of the specified anodic current, +A. Likewise, electrode E4 has been selected as the only cathode to sink current, and this electrode receives X = <NUM>% of that cathodic current, - A.

The GUI <NUM> as shown specifies only a pulse width PW of the first pulse phase 30a. The clinician programmer software <NUM> that runs and receives input from the GUI <NUM> will nonetheless ensure that the IPG <NUM> and ETS <NUM> are programmed to render the stimulation program as biphasic pulses if biphasic pulses are to be used. For example, the clinician programming software <NUM> can automatically determine durations and amplitudes for both of the pulse phases 30a and 30b (e.g., each having a duration of PW, and with opposite polarities +A and -A). An advanced menu <NUM> can also be used (among other things) to define the relative durations and amplitudes of the pulse phases 30a and 30b, and to allow for other more advance modifications, such as setting of a duty cycle (on/off time) for the stimulation pulses, and a ramp-up time over which stimulation reaches its programmed amplitude (A), etc. A mode menu <NUM> allows the clinician to choose different modes for determining stimulation parameters. For example, as described in the '<NUM> Publication, mode menu <NUM> can be used to enable electronic trolling, which comprises an automated programming mode that performs current steering along the electrode array by moving the cathode in a bipolar fashion.

While GUI <NUM> is shown as operating in the clinician programmer <NUM>, the user interface of the external controller <NUM> may provide similar functionality.

<FIG> shows an alternative embodiment of an implantable SCS system <NUM> comprising an implanted electrode lead <NUM> having electrodes <NUM> disposed thereon. The SCS system <NUM> does not use an implanted IPG to provide power for electrical stimulation. Instead, power is provided via radio frequency (RF) transmission through the patient's tissue <NUM> from an external power supply (EPS) <NUM>. The EPS has an RF antenna <NUM> configured to transmit RF power and the implanted lead <NUM> comprises an antenna <NUM> configured to receive the RF power. The implanted lead <NUM> also has simple circuitry (not shown) configured to rectify the RF power and generate pulses. As with the IPG system described above, the RF-powered system <NUM> may use an external controller <NUM> to control and transmit stimulation parameters. However, in the system <NUM>, the external controller <NUM> provides stimulation parameters to the EPS <NUM>, rather than to an implanted IPG. While the EPS <NUM> and the external controller <NUM> are illustrated as separate units in <FIG>, the EPS <NUM> and the external controller <NUM> may be combined as a single unit. The illustrated SCS system <NUM> has an advantage over the system illustrated in <FIG> in that the system <NUM> does not require a surgical procedure to implant an IPG (<NUM>, <FIG>) and tunnel lead wires (<NUM>, <FIG>) between the IPG and the electrode leads. However, a disadvantage of the system <NUM> (<FIG>) is that the patient must position the EPS <NUM> near their tissue any time that they wish to receive stimulation. The EPS <NUM> may be carried in a belt, pouch or other carrying device, for example. Systems as shown in <FIG>, which rely on RF energy provided by an EPS are referred to herein as "RF systems.

An exemplary not-claimed method of providing a prescribed amount of stimulation to a patient using an implantable stimulator device that is implantable in the patient and an external controller configured to control the implantable stimulator device is disclosed herein. According to some embodiments, the method comprises: receiving a prescription, wherein the prescription quantifies the prescribed amount of stimulation to be provided by the implantable stimulator device, using the external controller to instruct the implantable stimulator device to provide stimulation, tracking the provided stimulation and determine an amount of provided stimulation, determining a difference between the prescribed amount of stimulation and the amount of provided stimulation, wherein the difference indicates the amount of stimulation remaining on the prescription and/or an amount of the prescription used, and using the external controller to provide an indication of the difference. According to some embodiments, the prescribed amount of stimulation is based on a total amount of actively delivered charge to be delivered to the patient. According to some embodiments, the prescribed amount of stimulation is based on a total amount of time that stimulation is to be provided to the patient. According to some embodiments, the prescribed amount of stimulation is based on a total number of boluses of stimulation to be delivered to the patient. According to some embodiments, each bolus of stimulation comprises a specified duration during which stimulation is to be delivered to the patient. According to some embodiments, each bolus of stimulation comprises an amount of actively driven charge to be delivered to the patient. According to some embodiments, using the external controller to provide an indication of the difference comprises displaying an indication of the difference on a user interface of the external controller. According to some embodiments, using the external controller to provide an indication of the difference comprises sending a message to a remote location. According to some embodiments, receiving a prescription at the external controller comprises receiving the prescription from a clinician programmer. According to some embodiments, the steps of receiving a prescription, tracking the provided stimulation, and determining a difference between the prescribed amount of stimulation and the amount of provided stimulation are performed by the implantable stimulator device. According to some embodiments, the steps of receiving a prescription, tracking the provided stimulation, and determining a difference between the prescribed amount of stimulation and the amount of provided stimulation are performed by the external controller.

A system for providing a prescribed amount of stimulation to a patient using an implantable stimulator device that is implantable in the patient and an external controller configured to control the implantable stimulator device is described herein. According to some embodiments, the system is configured to: receive a prescription for stimulation, wherein the prescription quantifies the prescribed amount of stimulation to be provided by the implantable stimulator device, provide stimulation, track the provided stimulation and determine an amount of provided stimulation, determine a difference between the prescribed amount of stimulation and the amount of provided stimulation, wherein the difference indicates the amount of stimulation remaining on the prescription and/or an amount of the prescription used, and provide an indication of the difference. According to some embodiments, the system further comprises a clinician programmer configured to: determine the prescription for stimulation, and transmit the prescription for stimulation to the external controller. According to some embodiments, determining the prescription for stimulation comprises: receiving a stimulation program comprising one or more parameters of a stimulation waveform, receiving one or more inputs indicating an amount of stimulation to be provided to the patient, and calculating the prescription for stimulation based on the stimulation program and the one or more inputs.

Also disclosed herein is an exemplary not-claimed non-transitory computer-readable medium executable on an external controller configured to communicate with an implantable stimulator device, comprising instructions, which when executed by the external controller, configure the controller to: receive a prescription for stimulation, wherein the prescription quantifies a prescribed amount of stimulation to be provided by the implantable stimulator device, instruct the implantable stimulator device to provide stimulation, track the provided stimulation and determine an amount of provided stimulation, determine a difference between the prescribed amount of stimulation and the amount of provided stimulation, wherein the difference indicates the amount of stimulation remaining on the prescription and/or an amount of the prescription used, and provide an indication of the difference.

Also disclosed herein is an exemplary not-claimed method for providing stimulation to a patient using an implantable stimulator device and an external controller configured to control the implantable stimulator device, the method comprising: determining a bolus of stimulation therapy, wherein the bolus comprises a duration during which stimulation is applied and after which stimulation is terminated, using the external controller to instruct the implantable stimulator device to issue a bolus of stimulation therapy. According to some embodiments, determining a bolus of stimulation therapy comprises: issuing a plurality of trial boluses, wherein each trial bolus comprises a different duration, receiving an indication of effectiveness of each of the trial boluses, and based on the indications of effectiveness, determining the best bolus.

Also disclosed herein is an exemplary not-claimed method for providing stimulation to a patient using an implantable stimulator device and an external controller configured to control the implantable stimulator device (ISD), the method comprising: tracking instances when a patient uses the external controller to instruct the implantable stimulator device to issue a bolus of stimulation, wherein the bolus of stimulation comprises active stimulation for a first period of time and wherein after the first period of time the ISD provides no stimulation for a second period of time, correlating the instances with one or more predictors indicative of a need for stimulation, determining an occurrence of one or more of the predictors, and in response to the occurrence, either prompting the patient to issue a bolus of stimulation or automatically issuing a bolus of stimulation. According to some embodiments, the one or more predictors comprises a time of day. According to some embodiments, the one or more predictors is selected from the group consisting of a heartrate measurement, a blood pressure measurement, an activity level, a postural measurement, and a weather condition. According to some embodiments, the first period of time is ten minutes to thirty minutes. According to some embodiments, the second period of time is thirty minutes to twelve hours.

The invention may also reside in the form of a programed external device (via its control circuitry) for carrying out the above methods, a programmed IPG or ETS (via its control circuitry) for carrying out the above methods, a system including a programmed external device and IPG or ETS for carrying out the above methods, or as a computer readable media for carrying out the above methods stored in an external device or IPG or ETS.

Generally, when a patient has been identified as a candidate for neuromodulation therapy, such as spinal cord stimulation (SCS), the patient receives one or more surgically implanted electrode leads (such as leads <NUM>, <FIG>). The leads may then be connected to an external trial stimulator (ETS <NUM>, <FIG>), which allows the patient and his clinician to experiment with different stimulation parameters to try and find a stimulation program that alleviates the patient's symptoms (e.g., pain). If the trial stimulation proves successful, the patient may receive a fully implanted IPG (<NUM>, <FIG>). The patient will typically also receive an external controller (<NUM>, <FIG>), which may be programmed with one or more stimulation programs comprising the parameters that have been determined to be most effective. The external controller allows the patient to select the stimulation programs and also allows them to control various parameters of their therapy, such as stimulation intensity, duration, etc. Under current paradigms, the patient is simply released and they can self-administer therapy at will without returning to the physician for review of effectiveness or follow-up.

The inventors have recognized deficiencies with this treatment paradigm. For one, simply releasing the patient without further scheduled follow-ups may be a missed opportunity for further evaluation and optimization of the patient's therapy. This is in contrast to typical pharmaceutical treatment regimens in which a clinician prescribes a finite number of doses of a drug and requires a follow-up visit to refill the prescription.

Another problem with the present SCS treatment paradigm of allowing the patient the unfettered ability to self-medicate is that the patient may overuse stimulation and develop a tolerance to their stimulation. Overstimulation can reduce the effectiveness of therapy even in the absence of other side effects. A patient may increase the frequency and/or intensity of their stimulation in an effort to compensate for a decrease in the effectiveness of their therapy. But such increases in stimulation can actually negatively impact the patient's therapy because they accelerate the rate at which the patient develops a tolerance to the stimulation. An ideal system would enable a clinician to manage the use of stimulation so that the patient does not overuse the stimulation and reduce the therapy effectiveness.

Disclosed herein are systems and methods that enable a clinician to prescribe a set amount of stimulation that a patient can receive before requiring the patient to seek a further prescription for additional stimulation. According to some embodiments, the prescribed amount of stimulation can be programmed into the patient's external controller or into the IPG. The system may track the amount of stimulation used. The user interface of the external controller may include an indication of the amount of prescribed stimulation remaining. When the patient has used all of the prescribed stimulation, the patient may be directed to make an appointment for a follow-up visit with their clinician to obtain a "refill" for their stimulation prescription. According to some embodiments, the patient's external controller may be an internet connectable device, in which case, the external controller may be configured to send a message to the clinician indicating that the patient has used all of their prescribed stimulation so that the clinician can proactively contact the patient to arrange an appointment.

<FIG> illustrates a system <NUM> for prescribing and monitoring stimulation therapy. The system comprises a clinician programmer <NUM>, which includes the functionality described above. In addition, the clinician programmer <NUM> comprises one or more therapy prescription modules <NUM>, which are configured to aid the clinician in prescribing an amount of stimulation therapy. The therapy prescription module(s) <NUM> may be implemented as instructions embodied within non-transitory computer readable media associated with the clinician programmer <NUM> and executable by processing resources (i.e., one or more microprocessors and/or control circuitry) of the clinician programmer. Such execution configures the clinician programmer to perform the functionality of the prescription module <NUM>, which is described in more detail below.

The clinician programmer is configured to transmit the stimulation prescription to the patient's external controller <NUM> or to the patient's IPG <NUM>. The patient's external controller <NUM> may have all of the functionality described above for controlling the patient's IPG <NUM> (<FIG>, and <FIG>), ETS (<FIG>), and/or EPS <NUM> (<FIG>). In the illustrated embodiment, the external controller is configured with a stimulation tracking and display module <NUM> that is configured to receive the stimulation prescription from the clinician programmer <NUM>, track the amount of stimulation used, and display an amount of stimulation remaining on the prescription to the patient. The stimulation tracking and display module <NUM> may be implemented as instructions embodied within non-transitory computer readable media associated with the external controller <NUM> and executable by processing resources (i.e., one or more microprocessors and/or control circuitry) of the external controller. Such execution configures the external controller to perform the functionality of the stimulation tracking and display module. According to other embodiments, the prescription and the tracking of the stimulation used may be performed in the IPG, which can communicate the prescription/use information to the patient's external controller for display.

As the prescribed stimulation is used up, the patient may be prompted to schedule an appointment with their clinician to receive a further prescription for additional stimulation. As mentioned above, if the patient's external controller <NUM> is an internet-connected device, the external controller may be configured to send a notice to the clinician indicating that the patient's prescribed amount of stimulation is depleted or approaching depletion so that the clinician can proactively contact the patient to schedule an appointment. In embodiments wherein the IPG tracks the prescription, the IPG may be configured to send a notice to the patient's personal phone or other computing device (via a Bluetooth connection, for example) informing them that the prescription is depleted or nearing depletion. According to some embodiments, the clinician programmer <NUM> may be configured to refresh the prescription via an internet connection.

According to some embodiments, the prescribed amount of stimulation can be set as a total amount of actively delivered charge. <FIG> illustrates an example of an embodiment of an algorithm <NUM> that a clinician may use to determine and prescribe an amount of total charge to prescribe for a patient's therapy. The algorithm <NUM> may implemented as a program in the clinician programmer <NUM> (<FIG>), for example, as a component of a prescription module <NUM> (<FIG>). The algorithm assumes that the clinician and patient have determined one or more stimulation programs that are expected to be beneficial for the patient. The process of determining appropriate stimulation programs may be referred to as a fitting process.

At step <NUM> of the algorithm, the algorithm receives the stimulation parameters for the one or more programs that have been determined during the fitting process. For example, assume that the clinician has determined that the patient experiences pain relief when the patient is stimulated using a simple biphasic stimulation waveform, such as the waveform illustrated in <FIG>. Assume that the waveform has a frequency of <NUM>, an amplitude of <NUM> mA, and a pulse width of <NUM>. All of those parameters are provided to the algorithm at step <NUM>. Of course, the stimulation program could be more complex, for example, involving complex pulse shapes, pulse patterns, and the like. Moreover, multiple programs may be determined during the fitting process. But for simplicity, a single simple biphasic waveform is considered here.

At step <NUM> the algorithm analyzes the stimulation waveforms contained in the defined stimulation program and calculates the rate of charge injection into the patient (i.e., the amount of actively driven charge provided as a function of time) when executing the stimulation program. For example, the stimulation parameters listed above would nominatively pass <NUM> Coulombs of charge per hour when executing the stimulation program.

At step <NUM> the algorithm receives input indicating an amount of time that stimulation should ideally be applied before the patient returns for a follow-up visit. For example, assume that the clinician believes that the patient should generally applying stimulation for <NUM> hours per day and the clinician would like for the prescription to be adequate for six months, after which, the patient should return for a follow-up visit. The clinician would enter those time parameters into the user interface of the clinician programmer, for example, as part of the prescription module <NUM> (<FIG>).

At step <NUM> the algorithm calculates a charge prescription. In this simple example, the calculation is relatively straight forward. The values of the programmed stimulation parameters--amplitude, frequency, and pulse width--provide actively driven charge at a rate of <NUM> Coulombs per hour. That rate correlates to <NUM> Coulombs per day if the patient applies stimulation for <NUM> hours per day, which further correlates to <NUM> Coulombs over six months (<NUM> days). Thus, the prescription will be calculated as <NUM> Coulombs, based on the parameters provided by the clinician. It should be appreciated that since the algorithm has access to the stimulation waveform program and the relevant stimulation parameters, the algorithm can be configured to calculate the actively driven charge for generally any duration of stimulation, even for complex waveforms.

At step <NUM>, the calculated charge prescription can be transmitted from the clinician programmer to the patient's external controller. It should be noted that while the illustrated algorithm <NUM> computes a stimulation prescription based on Coulombs of charge, neither the clinician nor the patient may be interested in the absolute value of Coulombs, per se. Instead, the clinician can simply prescribe stimulation based on the particular stimulation parameters, the amount of stimulation per day, and the ideal length of time before a follow-up appointment. Given those data points, the algorithm <NUM> calculates a "charge prescription. " It should also be noted that the prescription may be determined on the basis of total energy or some other metric that relates to an amount of stimulation. For example, the clinician may prescribe stimulation on the basis of time, time per day, or boluses of stimulation, which is discussed in more detail below. The prescription module <NUM> executed on the clinician programmer may be configured with different options for allowing the clinician to prescribe stimulation.

<FIG> illustrates an embodiment of an external controller <NUM> having a display <NUM>. The external controller may comprise a stimulation tracking and display module <NUM> (<FIG>) configured to receive the stimulation prescription from the physician controller and to account for the amount of charge used during stimulation. The amount of charge remaining for the patient's prescription may be displayed on the display <NUM> of the patient's external controller. For example, in the illustrated embodiment, the external controller presents a gauge <NUM> indicating the amount of therapy remaining on the prescription. As the patient uses their SCS system their external controller can track the amount of charge used and may display the amount of charge remaining on the prescription (either as charge or some variable related to charge). When the patient's prescribed charge is depleted or approaching depletion, they may be prompted to schedule a follow-up appointment with the clinician. The patient may use their prescribed amount of stimulation at a faster rate than anticipated, for example, by applying stimulation more frequently or by using a greater amplitude or pulse width. In that case, the patient will be prompted to schedule a follow-up sooner than the anticipated six months. This may afford the patient and clinician to explore reasons that the patient is requiring more stimulation than anticipated.

According to some embodiments, stimulation may be provided in discreet chunks of stimulation, referred to as a "bolus" of stimulation. A bolus of stimulation may be thought of as analogous to a single dose of stimulation, similar to a dose of a pharmaceutical agent. For example, a bolus may comprise stimulation for a first period of time, such as <NUM> minutes of stimulation (or <NUM> minutes, or <NUM> hour, etc.). After a bolus is issued further stimulation is not provided until another bolus is issued. Typically, the time period between boluses (i.e., a second period of time) is on the order of at least minutes, or hours, for example. For example, according to some embodiments, the second period of time may be thirty minutes to twelve hours. However, according to some embodiments, a patient could issue themselves another bolus immediately following a first bolus, just as patient could take a second dose of a pharmaceutical immediately following a first dose.

It has been observed that some patients respond well to bolus mode treatment. A patient may initiate a bolus of stimulation when they feel pain coming on. Some patients experience extended pain relief, up to several hours or more, following receiving a bolus of stimulation. According to some embodiments, a clinician may prescribe stimulation therapy based on a number of boluses of stimulation. To draw an analogy to a pharmaceutical prescription, a clinician might prescribe a given number of boluses of stimulation to a patient per day for a certain duration. For example, a clinician might prescribe five <NUM>-minute boluses of stimulation per day for three months, after which the patient returns to the clinician for a follow-up evaluation.

<FIG> illustrates an example of a method <NUM> of determining and prescribing a bolus mode treatment. At step <NUM>, appropriate stimulation parameters are determined for the patient. This process is generally done in a fitting session with the aid of a clinician programmer <NUM> (<FIG>, <FIG>, and <FIG>), as described above. Assume that, during the fitting process, the clinician has determined one or more stimulation programs that alleviate the patient's pain and also assume that the clinician believes that the patient may respond well to bolus mode treatment. Having determined optimum stimulation parameters, the patient may be released with an implanted IPG (or ETS or EPS) and their external controller <NUM> to determine an appropriate time period corresponding to a bolus of stimulation. For example, the stimulation tracking and display module <NUM> in the patient's external controller may be programmed with a bolus algorithm configured to help the patient and clinician determine an appropriate bolus of stimulation. The goal is to determine a time period of stimulation that achieves long-lasting pain relief. When the patient experiences the onset of pain, they may activate a trial bolus. For example, a trial bolus may comprise <NUM> minutes of stimulation using the patient's optimum stimulation parameters. The patient will receive a bolus of stimulation, after which the stimulation will terminate. The patient may then be asked to periodically rate their pain relief (for example, every hour after the administration of the trial bolus) using the interface of their external controller. Over a period of days or weeks, different time periods of stimulation may be tried to determine a minimum time period that provides the longest-lasting pain relief. Various optimization criteria may be used for making the determination of an optimum bolus, depending on the patient's and the clinician's preferences. Alternatively, the clinician may simply decide what time period of stimulation will constitute a bolus of stimulation at step <NUM>.

Having determined an appropriate stimulation duration corresponding to a bolus of stimulation, the patient may receive a prescription for a number of boluses (step <NUM>). According to some embodiments, the patient may return to their clinician following the bolus determination step (step <NUM>) so that the clinician can program the patient's external controller with a prescription for a given number of boluses. According to some embodiments, if the patient's external controller is an internet-connected device, the patient may not need to return to the clinician. Instead, the patient's external controller may transmit the bolus duration to the clinician programmer via an internet connection and the clinician programmer may transmit the bolus prescription to the patient's external controller via the internet connection. Once the patient's external controller is programmed with a bolus prescription, the external controller can monitor the number of boluses used (Step <NUM>). The number of boluses remaining on the patient's prescription may be displayed on the external controller. Once the patient has used the prescribed number of boluses, the patient may be prompted to schedule a follow-up visit with the clinician.

It should be noted that, according to some embodiments, the clinician may simply prescribe a certain stimulation duration as a bolus without using an algorithm such as the algorithm <NUM>. For example, the clinician may simply decide that a bolus of stimulation will correspond to ten minutes of stimulation. Alternatively, according to some embodiments, the patient's external controller may be programmed with an algorithm that helps the patient determine an appropriate bolus of stimulation without approval of the clinician. For example, the patient's external controller may be programmed with a bolus calibration duration, for example, two weeks, during which the patient is prompted to rank therapy using different bolus durations. After the calibration duration, the external controller considers the determined optimum duration of stimulation as a bolus of stimulation. The external controller may then begin tracking the number of boluses remaining for the patient's prescription. For example, the GUI of the external controller may inform the patient that they have x of y boluses remaining.

According to some embodiments, the patient's external controller may be programmed with one or more algorithms that attempt to optimize when a bolus of stimulation should issue. When the algorithm determines that a bolus should be issued, the patient's external controller may alert the patient to administer themselves a bolus of stimulation. Such an embodiment may be particularly useful for patients using an RF system (i.e., a system without an implanted IPG). A patient using such a system can receive a notice or alert when it is time to receive a bolus of stimulation and the patient can then arrange their external power supply (EPS) appropriately an administer themselves a bolus. Alternatively, a patient using a system with a traditional IPG can use their external controller to cause the IPG to issue a bolus of stimulation when they receive an alert that it is time to issue a bolus. According to some embodiments, the external controller may simply instruct the IPG to issue a bolus automatically without the patient instructing the external controller to so. According to some embodiments, the patient may receive an alert on their personal computing device, such as a personal phone, that it is time to take a bolus.

<FIG> illustrates an example of an algorithm <NUM> for predicting when a bolus should issue. The algorithm <NUM> comprises a "training period" during which the algorithm attempts to correlate one or more "pain predictors" with instances that the patient issues themselves a bolus. The pain predictor is a predictor indicative of a need for stimulation. Examples of pain predictors may include the time of day, the weather, the patient's activity level, or one or more physiological parameters of the patient, such as heartrate, blood pressure, posture, or the like. For example, during the training period the algorithm may determine that the patient tends to issue themselves a bolus at certain times during the day. The algorithm may therefore determine that those are the times of day that the patient tends to experience pain. Likewise, the algorithm may determine that the patient tends to administer a bolus when they transition from sitting to standing, or vice-versa. Such postural changes may be detected using measured evoked compound action potentials (ECAPs) or other sensed neural responses. Alternatively (or additionally), postural changes and/or patient activity level may be determined using accelerometers. Physiological parameters, such as heartrate, blood pressure, and the like may be determined using one or more physiological sensors associated with the patient. According to some embodiments, pain predictors such as activity level, weather, posture, and the like, may be determined based on patient input, for example, via an application running on their external controller or other external device in communication with their external controller. Alternatively, to determine weather conditions, the patient's external controller (or other external device in communication with the external controller) may be configured to obtain weather information via internet weather data. The training period may be a few days or a few weeks, for example.

Once the training period is concluded, the algorithm may proceed to a directed therapy or automatic therapy regime wherein the algorithm monitors for one or more of the pain predictors. When a pain predictor is detected the algorithm may either instruct the patient to preemptively issue themselves a bolus or may automatically issue the patient a bolus without patient input. As mentioned above, embodiments wherein the patient is instructed to issue themselves a bolus are particularly useful for patients with an RF system that does not use an implanted IPG.

According to some embodiments, the patient may be prompted for feedback ranking the effectiveness of the attempted therapy programs, for example, by selecting a ranking on the user interface of their external controller. Based on the patient feedback, the algorithm may attempt to optimize the algorithm.

<FIG> illustrate an example of the algorithm <NUM> for determining when to preemptively issue a bolus of stimulation. The example algorithm <NUM> illustrated in <FIG> uses the time of day as the pain predictor and also uses patient feedback to optimize the algorithm. <FIG> illustrates a training period where the patient self-administers a bolus (represented by a capsule in <FIG>) each time they perceive the onset of pain (represented by a lighting bolt). According to some embodiments, an algorithm may track the times that the patient issues themselves a bolus and then attempt to preemptively issue a bolus before the patient experiences pain onset. Notice in <FIG> that the patient's pain onset events are weighted more heavily to the early part of the day. Assume that the algorithm <NUM> has tracked the three days of therapy illustrated in <FIG> illustrates an attempt by the algorithm to preemptively issue boluses of therapy over a three-day period based on the boluses that the patient administered in <FIG>. For example, in <FIG>, the patient, on average, administered three boluses per day. So, in <FIG>, the algorithm <NUM> automatically provides those boluses each day at time periods that best match those in <FIG>. The patient can continue to self-administer boluses and the algorithm <NUM> can continue to optimize the timing of automatically providing boluses. For example, on days one and three, the preemptively issued boluses of were not sufficient to completely curtail the patient's pain and the patient had to self-administer an extra bolus on those days. In <FIG>, the patient has rated the therapy two-out-of-five. In <FIG>, the algorithm has attempted to improve the therapy by issuing the third bolus earlier in the day, corresponding to the self-administered boluses. The patient has not had to self-administer a bolus of stimulation over a three-day period and has ranked the therapy a four-out-of-five. The algorithm <NUM> may thus determine that the timing determined in Figure 10C may be used as ongoing therapy.

Bolus mode therapy may provide several advantages compared to traditional continuous therapy. For example, bolus mode therapy may decrease the chances that the patient overuses stimulation, thereby developing a tolerance to the therapy. Also, bolus mode therapy is particularly well suited for RF stimulation systems, such as described above with reference to <FIG>. Since a bolus of stimulation is only applied for a finite duration of time, a patient using an RF system need only have access to their external power supply during the time they are receiving a bolus of stimulation.

Various aspects of the disclosed techniques, including processes implementable in the IPG or ETS, or in external devices such as the clinician programmer and/or the external controller can be formulated and stored as instructions in a computer-readable media associated with such devices, such as in a magnetic, optical, or solid-state memory. The computer-readable media with such stored instructions may also comprise a device readable by the clinician programmer or external controller, such as in a memory stick or a removable disk, and may reside elsewhere. For example, the computer-readable media may be associated with a server or any other computer device, thus allowing instructions to be downloaded to the clinician programmer system or external controller or to the IPG or ETS, via the Internet for example. The various algorithms described herein and stored in non-transitory computer readable media can be executed by one or more microprocessors and/or control circuitry configured within the relevant device, thereby causing the device to perform the steps of the algorithm(s).

Note that some of the applications to which this present disclosure claim priority, which are incorporated by reference above, are directed to concepts (e.g., picking optimal stimulation parameters, and in particular stimulation parameters that cause sub-perception at lower frequencies) that are relevant to what is disclosed. Techniques in the present disclosure can also be used in the context of these priority applications. For example, the prescribed stimulation may be determined and optimized using the techniques described in some of the priority applications. Also, the parameters of the bolus stimulation may be determined and optimized using the techniques described in some of the priority applications.

Claim 1:
A system (<NUM>) for providing stimulation to a patient, the system comprising: an implantable stimulator device,ISD, (<NUM>) that is implantable in the patient and an external controller (<NUM>) configured to control the implantable stimulator device (<NUM>), wherein the external controller (<NUM>) is configured to:
track instances when the patient uses the external controller to instruct the ISD to issue a bolus of stimulation, wherein the bolus of stimulation comprises active stimulation for a first period of time and wherein after the first period of time the ISD provides no stimulation for a second period of time,
correlate the tracked instances with one or more predictors indicative of a need for stimulation,
determine an occurrence of one or more of the predictors, and
in response to the occurrence, (i) prompt the patient to issue a bolus of stimulation; or (ii) automatically instruct the ISD to issue a bolus of stimulation.