APPARATUS AND METHOD FOR REMINDING, PROMPTING, OR ALERTING A PATIENT WITH AN IMPLANTED STIMULATOR

Abstract

An implanted stimulator can deliver a patient-detectable electrical stimulation to remind or prompt a patient to interact with an implanted therapeutic device (e.g., neurostimulator) when a prompting event occurs. For example, the apparatuses and methods described herein may be configured to apply a prompting patient-detectable electrical vagus nerve stimulation to remind a patient that it is time to administer a therapeutic dose. When the therapeutic device is operated in an automatic fashion, the apparatus can also deliver a patient-detectable warning stimulation prior to the therapeutic stimulation to let the patient know that a therapeutic stimulation will be delivered soon thereafter.

Claims

1. A method for prompting a patient to interact with a therapy device implanted in the patient, the method comprising: determining, in a processor, if the patient should interact with the therapy device; and delivering a patient-detectable stimulation from the implanted therapy device when the processor determines that the patient should interact with the therapy device, wherein the patient-detectable prompting stimulation is different from a therapeutic dose for the implanted therapy device.

2. A method for prompting a patient to interact with a therapy device implanted in the patient, the method comprising: determining, in a processor, if the patient should interact with the therapy device based on a prompting event selected from the group comprising: the implant requires charging, the implant requires maintenance, or it is time to prompt the patient to manually activate the implanted therapy device to deliver a therapeutic dose; and delivering a patient-detectable prompting stimulation from the implanted therapy device when the processor determines that the patient should interact with the therapy device, wherein the patient-detectable stimulation is different from a therapeutic dose for the implanted therapy device.

3. A method for prompting a patient to interact with a therapy device implanted in the patient, the method comprising: determining that the patient should interact with the therapy device to manually activate the implanted therapy device to deliver a therapeutic stimulation, wherein determining comprises comparing a current time with a scheduled stimulation time; and delivering a patient-detectable prompting stimulation from the implanted therapy device to remind the patient to manually activate the implanted therapy device to apply therapeutic stimulation from the implanted therapy device when the current time falls within a reminder time period prior to the scheduled stimulation time.

4. A method for alerting a patient that an implanted therapy device will be delivering a therapeutic dose prior to delivery of the dose, the method comprising: determining, in a processor, that the therapeutic device is scheduled to deliver a therapeutic dose within a predetermined reminder time period from a current time; and delivering a patient-detectable stimulation from the implanted therapy device prior to delivery of the therapeutic dose when the processor determines that the therapeutic dose will be delivered within the predetermine reminder time period, wherein the patient-detectable prompting stimulation is different from a therapeutic dose for the implanted therapy device.

5. The method of claim 1, wherein delivering the patient-detectable prompting stimulation comprises delivering electrical stimulation to the subject's vagus nerve from the implanted therapy device.

6. The method of claim 1, wherein determining if the patient should interact with the therapy device comprises determining if a prompting event has occurred, wherein the prompting event is selected from the group comprising: the implant requires charging, the implant requires maintenance, or it is time to prompt the patient to manually activate the implanted therapy device to deliver a therapeutic dose.

7. The method of claim 3, further comprising determining whether the patient has delivered the therapeutic stimulation by the scheduled stimulation time.

8. The method of claim 1, wherein delivering the patient-detectable prompting stimulation comprises delivering a stimulation that has a lower amplitude and duration than the therapeutic dose from the implanted therapy device.

9. The method of claim 1, wherein delivering the patient-detectable prompting stimulation comprises delivering electrical stimulation to the patient's vagus nerve from the implanted therapy device at a lower amplitude than the therapeutic dose applied to the patient's vagus nerve from the implanted therapy device.

10. The method of claim 1, wherein determining comprises determining in a processor in the implant.

11. The method of claim 1, further comprising determining that the patient has failed to interact with the therapy device following delivery of the patient-detectable prompting stimulation and delivering a second patient-detectable prompting stimulation.

12. The method of claim 2 wherein delivering the patient-detectable prompting stimulation comprises delivering a patient-detectable prompting stimulation that is characteristic of the prompting event.

13. The method of claim 3, wherein the reminder period is about 15 minutes or less.

14. The method of claim 1, wherein the therapeutic stimulation comprises electrical stimulation to the vagus nerve.

15. A vagus nerve stimulation system that prompts a patient to interact with the system, the system comprising: an implantable neurostimulator configured to electrically stimulate a vagus nerve of the patient to deliver a therapeutic dose; and a processor, wherein the processor is programmed to: determine if a prompting event has occurred, and trigger delivery of a patient-detectable prompting stimulation from the neurostimulator when the processor determines that the patient should interact with the neurostimulator, wherein the patient-detectable stimulation is different from the therapeutic dose.

16. A vagus nerve stimulation system that prompts a patient to interact with the system, the system comprising: an implantable neurostimulator configured to electrically stimulate a vagus nerve of the patient to deliver a therapeutic dose; and a processor in communication with the neurostimulator, wherein the processor is programmed to: determine if the patient should interact with the neurostimulator based on a prompting event selected from the group comprising: the implant requires charging, the implant requires maintenance, or it is time to prompt the patient to manually activate the implanted neurostimulator to deliver the therapeutic dose, and trigger delivery of a patient-detectable prompting stimulation from the neurostimulator when the processor determines that the patient should interact with the neurostimulator, wherein the patient-detectable stimulation is different from the therapeutic dose.

17. A vagus nerve stimulation system that prompts a patient prior to providing a scheduled therapeutic dose, the system comprising: an implantable neurostimulator configured to electrically stimulate a vagus nerve of the patient to deliver a therapeutic dose at a dosing schedule; and a processor, wherein the processor is programmed to: determine if the neurostimulator is scheduled to deliver the therapeutic dose within a predetermined reminder time period from a current time, and trigger delivery of a patient-detectable prompting stimulation from the neurostimulator when the processor determines that the therapeutic dose will be delivered within the predetermine reminder time period, wherein the patient-detectable stimulation is different from the therapeutic dose.

18. The system of claim 14 where in the processor is programmed to determining if the prompting event has occurred wherein the prompting event is selected from the group comprising: the implant requires charging, the implant requires maintenance, or it is time to prompt the patient to manually activate the implanted therapy device to deliver the therapeutic dose.

19. The system of claim 14 wherein the processor is programmed to determine whether the patient has interacted with the system by a predetermined time after triggering delivery and to trigger a second patient-detectable prompting stimulation from the neurostimulator if the patient has not.

20. The system of claim 14, wherein the neurostimulator is configured to be triggered by the processor to deliver the patient-detectable stimulation.

21. The system of claim 14, wherein the neurostimulator is configured to be triggered by the processor to deliver the patient-detectable stimulation, wherein the patient-detectable stimulation has a lower amplitude and duration than the therapeutic dose from the neurostimulator.

22. The system of claim 14, wherein the neurostimulator is configured to be triggered by the processor to deliver the patient-detectable stimulation, wherein the patient-detectable stimulation has a lower amplitude than the therapeutic dose.

23. The system of claim 14, wherein the processor is housed within the implantable neurostimulator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1A shows one variation of a system for modulating chronic inflammation including a leadless microstimulator (shown connected to the vagus nerve) and an external charger/controller.

[0032] FIG. 1B shows another variation of a system for modulating chronic inflammation, including a microstimulator, charger (“energizer”), and system programmer/controller (“prescription pad”).

[0033] FIG. 1C shows another variations of a system for modulating chronic inflammation, including a microstimulator, a securing device (POD) for securing the leadless stimulator to the nerve, an external charger, a system programmer/controller (“prescription pad”) and an optional surgical tester.

[0034] FIG. 1D is a block diagram schematically illustrating the microstimulator and the charger.

[0035] FIG. 2 illustrates one variation of an external system programmer/controller wirelessly connected to a microstimulator.

[0036] FIG. 3A shows one variation of a microstimulator in a POD configured to surround a nerve of the inflammatory reflex.

[0037] FIG. 3B shows an enlarged view of the microstimulator and POD.

[0038] FIG. 3C shows another variation of a microstimulator.

[0039] FIG. 3D shows the microstimulator of FIG. 3C within a POD.

[0040] FIG. 3E shows another variation of the microstimulator.

[0041] FIG. 4 shows a schematic diagram of a microstimulator and POD around vagus nerve.

[0042] FIG. 5 is a flowchart that illustrates one embodiment of a reminder system.

[0043] FIG. 6 is a flowchart that illustrates another embodiment of a reminder system.

DETAILED DESCRIPTION

[0044] In general, described herein are methods and apparatuses for performing these methods, of applying a communication to a patient from an implanted therapeutic device. This communication may be referred to as a notice, warning, alert, reminder, or prompt, and typically includes a stimulation that is detectable by the patient, but is distinct from a therapeutic dose from the implant. The methods and apparatuses described herein, including the example, are directed primarily to vagus nerve stimulation apparatuses and methods; however, it should be understood that these methods and apparatuses may be used with virtually any implanted therapeutic stimulation device, including microstimulators that are not connected to the vagus nerve.

[0045] In general, the communication may be referred to herein as a prompt, notice, warning, alert, reminder, or the like, which may be used interchangeable and/or may refer to the goal or function of the communication; they may otherwise have similar or identical characteristics. For example, a prompt, notice, warning, alert, or reminder (referred to for convenience as a prompt) may be patient-detectable stimulation that is of the same mode (e.g., electrical, mechanical, etc.) as the therapeutic stimulation (dose) provided by the implant. In some variations, but not all, the prompt has stimulation parameters that are sub-therapeutic compared to a therapeutic dose. For example, the prompt may have stimulation parameters that are lower in intensity (e.g., current amplitude, voltage, etc.), frequency, and/or duration than the therapeutic dose being delivered to that patient. In some variations, the prompt stimulation range (also referred to below as “reminder stimulation range”) may be within the same range limits as therapeutic doses (e.g., between 1-5000 μA, etc.). The prompt stimulation may be adjusted separately (by a user, clinician, technician, etc.), so that it is noticeable by the patient (whereas in some variations the dose stimulation may not be immediately noticeable). For example, for a particular patient with an implanted therapy device, a dose may be set at an effective stimulation dose (amplitude, frequency, duration, etc.), and the prompting dose may be selected so that it is distinct from the stimulation dose and detectable by the patient. In some variations the prompt stimulation may have a greater amplitude (e.g. current amplitude) but may have a shorter duration and/or different frequency.

Vagus Nerve Stimulation System

[0046] Systems for electrically stimulating one or more nerves to treat chronic inflammation may include an implantable, wireless microstimulator such as those described herein and an external charging device (which may be referred to as a charging wand, charger, or energizer). In some variations the system also includes a controller such as a “prescription pad” that helps control and regulate the dose delivered by the system. The microstimulator may be secured in position using a securing device (which may be referred to as a “POD”) to hold the microstimulator in position around or adjacent to a nerve. These microstimulators are designed and adapted for treatment of chronic inflammation, and may be configured specifically for such use. Thus, an implantable microstimulator may be small, and adapted for the low duty-cycle stimulation to modulate inflammation. For example, the implantable microstimulator may hold a relatively small amount of power over weeks or even months and discharge it at a rate sufficient to modulate the anti-inflammatory pathway without significantly depressing heart rate or triggering any number of unwanted effects from the vagus nerve or other neural connections. Any of the nerves of the inflammatory reflex, including the vagus nerve, may be treated as described herein using the systems described.

[0047] For example, FIG. 1A illustrates one variation of a system for treating chronic inflammation that includes a microstimulator contained in POD that is mounted on cervical vagus nerve and charged a programmed by an external charger/programmer unit. This variation of a system includes a microstimulator 103 that has been implanted to contact the vagus nerve as shown. The implant may be programmed, controlled and/or charged by a charger/controller 105 device. In this variation the charger/controller is a loop with a wand region.

[0048] FIG. 1B shows another variation of a system for treating chronic inflammation that also includes an implantable microstimulator 103 (shown inserted into a POD to hold it in position relative to a nerve) and a charging device (“energizer” 105) configured as a collar to be worn around the subject's neck and charge the implant. Optionally, the system may include a prescription pad 107 which may be a separate dedicated device or part of a mobile or other handheld device (e.g., an application to run on a handheld device).

[0049] FIG. 1C shows another variation of a system for treating chronic inflammation. The systems described herein may also be referred to as systems for the neural stimulation of the cholinergic anti-inflammatory pathway (NCAP). These systems may be configured as chronic implantable systems. In some variations, the systems are configured to treat acutely (e.g., acute may 8 hours or less), sub-acutely (expected to occur for fewer than 30 days), or chronically (expected to occur for more than 30 days).

[0050] In general, the systems described herein may be configured to apply electrical stimulation at a minimum level necessary to modulate the inflammatory reflex (e.g., modulating cytokine release) characterized by the Chronaxie and rheobase. Chronaxie typically refers to the minimum time over which an electric current double the strength of the rheobase needs to be applied in order to stimulate the neuron. Rheobase is the minimal electrical current of infinite duration that results in an action potential. As used herein, cytokines refer to a category of signaling proteins and glycoproteins that, like hormones and neurotransmitters, are used extensively in cellular communication.

[0051] The NCAP Systems described herein are typically intended for the treatment of chronic inflammation through the use of implanted neural stimulation devices (microstimulators) to affect the Neural Stimulation of the Cholinergic Anti-inflammatory Pathway (NCAP) as a potential therapeutic intervention for rheumatologic and other inflammation-mediated diseases and disorders. Neurostimulation of the Cholinergic Anti-inflammatory Pathway (NCAP) has been shown to modulate inflammation. Thus, the treatment and management of symptoms manifested from the onset of disease (e.g., inflammatory disease) is based upon the concept of modulating the Cholinergic Anti-inflammatory Pathway. The NCAP pathway normally maintains precise restraint of the circulating immune cells. As used herein, the CAP is a reflex that utilizes cholinergic nerve signals traveling via the Vagus nerve between the brain, chemoreceptors, and the reticuloendothelial system (e.g., spleen, liver). Local release of pro-inflammatory cytokines (e.g., tumor necrosis factor or TNF) from resident immune cells is inhibited by the efferent, or indirectly by afferent vagus nerve signals. NCAP causes important changes in the function and microenvironment of the spleen, liver and other reticuloendothelial organs. Leukocytes which circulate systemically become “educated” as they traverse the liver and spleen are thereby functionally down regulated by the affected environment of the reticuloendothelial system. This effect can potentially occur even in the absence of an inflammatory condition.

[0052] Under this model, remote inflammation is then dampened by down-regulated cytokine levels. Stimulation of the vagus nerve with a specific regiment of electrical pulses regulates production of pro-inflammatory cytokines. In-turn, the down regulation of these cytokines may reduce localized inflammation in joints and other organs of patients with autoimmune and inflammatory disorders.

[0053] The NCAP System includes a neurostimulator that may trigger the CAP by stimulating the cervical vagus nerve. The NCAP System issues a timed burst of current controlled pulses with sufficient amplitude to trigger the CAP at a particular interval. These two parameters, Dose Amplitude and Dose Interval, may be used by a clinician to adjust the device. For example, the clinician may set the Dose Amplitude by modifying the current level. The Dose Interval may be set by changing the duration between Doses (e.g. 12, 24, 48 hours).

[0054] In some variations, dose amplitude may be set to within the Therapy Window. The Therapy window is defined as the lower limit of current necessary to trigger the CAP, and the upper limit is the level at which the Patient feels uncomfortable. The lower limit is called the Threshold (T), and the uncomfortable level is called Upper Comfort Level (UCL).

[0055] Dose Amplitude thresholds are nonlinearly dependent upon Current (I), Pulse width (PW), Pulse Frequency (PF), and Burst Duration (BD). Amplitude is primarily set by charge (Q), that is Current (I)×Pulse width (PW). In neurostimulation applications current has the most linear relationship when determining thresholds and working within the therapy window. Therefore, the clinician may modify Dose Amplitude by modifying current. The other parameters are held to experimentally determined defaults. Pulse width is selected to be narrow enough to minimize muscle recruitment and wide enough to be well above the chronaxie of the targeted neurons. Stimulus duration and pulse frequency was determined experimentally in Preclinical work.

[0056] Dose Interval may be specific for particular diseases and the intensity of diseases experienced by a patient. Our initial research has indicated that the cervical portion of the vagus nerve may be an ideal anatomic location for delivery of stimulation. The nerve runs through the carotid sheath parallel to the internal jugular vein and carotid artery. At this location, excitation thresholds for the vagus are low, and the nerve is surgically accessible. We have not found any significant difference in biomarker modulation (e.g., modulation of cytokines) between right and left. Even though the right vagus is thought to have lower thresholds than the left in triggering cardiac dysrythmias, the thresholds necessary for NCAP are much lower than those expected to cause such dysrythmias. Therefore a device delivering NCAP can safely be applied to either the right or left vagus.

[0057] We have also found, surprisingly, that the Therapy Window is maximized on the cervical vagus through the use of a bipolar cuff electrode design. Key parameters of the cuff may be: spacing and shielding of the contacts. For example, the contact points or bands may be spaced 1-2 diameters of the vagus nerve apart, and it may be helpful to shield current from these contacts from other nearby structures susceptible to inadvertent triggering. The cuff may be further optimized by using bands which are as long and wide as possible to reduce neurostimulator power requirements.

[0058] Thus, any variations of the systems described herein (e.g., the NCAP system) may be implemented with a Cuff, Lead and Implantable Pulse Generation (IPG), or a Leadless Cuff. The preferred implementation is a leadless cuff implemented by a microstimulator with integral electrode contacts in intimate contact with the nerve and contained within a Position (or protection) and Orientation Device (POD). This is illustrated in FIGS. 3A and 3B. The POD 301 may form a current shield, hold the microstimulator into place against the vagus nerve, and extend the microstimulator integral contacts with integral contacts in the POD itself. The POD is typically a polymer shell that encapsulates a microstimulator implant and that allows a nerve to run through the interior against the shell wall parallel to the length of the microstimulator implant. Within the shell of the POD, the microstimulator implant remains fixed against the Vagus nerve so the electrodes remain in contact with the nerve. The POD anchors the implant in place and prevents the implant from rotating or separating from the nerve, as well as maintaining contact between the electrodes and the nerve and preserving the orientation as necessary for efficient external charging of the microstimulator battery.

[0059] Referring back to FIG. 1C, the system may include an implantable microstimulator contained in a POD, a Patient Charger, and a prescription pad that may be used by the clinician to set dosage parameters for the patient. This system may evaluate the efficacy, safety, and usability of an NCAP technology for chronic treatment of clinical patients. The system can employ a Prescription Pad (external controller) that may include the range of treatment options.

[0060] As described in more detail in U.S. patent application Ser. No. 12/874,171, filed on Sep. 1, 2010, titled “PRESCRIPTION PAD FOR TREATMENT OF INFLAMMATORY DISORDERS,” Publication No. US-2011-0054569-A1, previously incorporated by reference in its entirety, the Prescription Pad may incorporate workflows in a simplified interface and provide data collection facilities that can be transferred to an external database utilizing commercially robust and compliant methods and procedures. In use, the system may be recommended for use by a clinician after assessing a patient; the clinician may determine that treatment of chronic inflammation is warranted. The clinician may then refer the patient to an interventional doctor to implant the microstimulator. Thereafter then clinician (or another clinician) may monitor the patient and adjust the device via a wireless programmer (e.g. prescription pad). The clinician may be trained in the diagnosis and treatment procedures for autoimmune and inflammatory disorders; the interventional placement of the system may be performed by a surgeon trained in the implantation of active neurostimulation devices, with a sufficient depth of knowledge and experience regarding cervical and vagal anatomy, experienced in performing surgical dissections in and around the carotid sheath.

[0061] The system may output signals, including diagnostics, historical treatment schedules, or the like. The clinician may adjust the device during flares and/or during routine visits. Examples of implantation of the microstimulator were provided in U.S. patent application Ser. No. 12/874,171, filed on Sep. 1, 2010, titled “PRESCRIPTION PAD FOR TREATMENT OF INFLAMMATORY DISORDERS,” Publication No. US-2011-0054569-A1. For example, the implant may be inserted by making an incision in the skin (e.g., cm) along Lange's crease between the Facial Vein and the Omohyoid muscle, reflecting the Sternocleidomastoid and gaining access to the carotid sheath. The IJV may be displaced, and the vagus may be dissected from the carotid wall (≦2 cm). A sizing tool may be used to measure the vagus, and an appropriate Microstimulator and POD Kit (small, medium, large) may be selected. The POD may then be inserted under nerve with the POD opening facing the surgeon, so that the microstimulator can be inserted inside POD so that the microstimulator contacts capture the vagus. The POD may then be sutured shut. In some variations a Surgical Tester may be used to activate the microstimulator and perform system integrity and impedance checks, and shut the microstimulator off, during or after the implantation. In other variations the surgical tester may be unnecessary, as described in greater detail below.

[0062] A physician may use the Patient Charger to activate the microstimulator, perform integrity checks, and assure sufficient battery reserve exists. Electrodes may be conditioned with sub-threshold current and impedances may be measured. A Physician may charge the microstimulator. In some variations a separate charger (e.g., an “energizer”) may be used by the patient directly, separate from the controller the physician may use. Alternatively, the patient controller may include controls for operation by a physician; the system may lock out non-physicians (e.g., those not having a key, code, or other security pass) from operating or modifying the controls.

[0063] In general, a physician may establish safe dosage levels. The physician may slowly increment current level to establish a maximum limit (Upper Comfort Limit). This current level may be used to set the Dosage Level. The exact procedure may be determined during this clinical phase.

[0064] The Physician may also specify dosing parameters that specify dosage levels and dosage intervals. The device may contain several concurrent dosing programs which may be used to acclimate the patient to stimulus, gradually increase dosage until efficacy is achieved, reset tachyphylaxis, or deal with unique patient situations.

[0065] In some variations, the Prescription Pad may be configured to handle multiple patients and may index their data by the microstimulator Serial Number. For example, a Prescription Pad may handle up to 100,000 patients and 10,000 records per patient, and may store the data in its local memory and may be backed up on an external database. In some variations, during each charging session, accumulated even log contents will be uploaded to the Patient Charger for later transfer to Prescription Pad. The data may or may not be cleared from the microstimulator. For example, FIG. 2 shows the addition of a prescription pad 203 wirelessly connected to the charger/programmer 207.

[0066] The microstimulators described herein are configured for implantation and stimulation of the cholinergic anti-inflammatory pathway, and especially the vagus nerve. In particular the microstimulators described herein are configured for implantation in the cervical region of the vagus nerve to provide extremely low duty-cycle stimulation sufficient to modulate inflammation. These microstimulators may be adapted for this purpose by including one or more of the following characteristics, which are described in greater detail herein: the conductive capsule ends of the microstimulator may be routed to separate electrodes; the conductive capsule ends may be made from resistive titanium alloy to reduce magnetic field absorption; the electrodes may be positioned in a polymer saddle; the device includes a suspension (e.g., components may be suspended by metal clips) to safeguard the electronics from mechanical forces and shock; the device may include an H-bridge current source with capacitor isolation on both leads; the device may include a built in temperature sensor that stops energy absorption from any RF source by detuning the resonator; the device may include a built-in overvoltage sensor to stop energy absorption from any RF source by detuning resonator; the system may include DACs that are used to calibrate silicon for battery charging and protection; the system may include DACs that are used to calibrate silicon for precision timing rather than relying on crystal oscillator; the system may include a load stabilizer that maintains constant load so that inductive system can communicate efficiently; the system may include current limiters to prevent a current rush so that the microstimulator will power up smoothly from resonator power source; the system may extract a clock from carrier OR from internal clock; the device may use an ultra-low power accurate RC oscillator that uses stable temperature in body, DAC calibration, and clock adjustment during charging process; the device may use a solid state UPON battery that allows fast recharge, supports many cycles, cannot explode, and is easy to charge with constant voltage; and the device may include a resonator that uses low frequency material designed not to absorb energy by high frequency sources such as MRI and Diathermy devices.

[0067] Many of these improvements permit the device to have an extremely small footprint and power consumption, while still effectively modulating the vagus nerve.

[0068] FIG. 3A is a perspective drawing of the Pod containing the microstimulator. Sutures (not shown) are intended to be bridged across one to three sets of holes. Electrodes integrated into the pod are not shown but would extend as bands originating and ending on the two outer pairs of suture holes.

[0069] In some variations, including those described above, the microstimulator consists of a ceramic body with hermetically sealed titanium-niobium ends and integral platinum-iridium electrodes attached. The microstimulator may be designed to fit within a POD 309, as shown in FIGS. 3A-3D. As described above, the POD is a biocompatible polymer with integrated electrodes that may help the microstimulator to function as a leadless cuff electrode. In some variations, such as the variation shown in FIG. 3E, contained within the hermetic space of the microstimulator 301 is an electronic assembly that contains a rechargeable battery 321, solenoid antenna 323, hybrid circuit 325 and electrode contacts (Ti Alloy braze ring and end cap) 327 at each end to make contact with the titanium/platinum case ends.

[0070] As mentioned above, some of the device variations described herein may be used with a POD to secure the implant (e.g., the leadless/wireless microstimulator implant) in position within the cervical region of the vagus nerve so that the device may be programmed and recharged by the charger/programmer (e.g., “energizer”). For example, FIG. 4 shows a schematic diagram of a POD containing a microstimulator. The cross section in FIG. 4 shows the ceramic tube containing electronic assembly that includes the hybrid, battery and coil. The rigid or semi-rigid contacts are mounted on the tube and surround the oval vagus nerve. The POD surrounds the entire device and includes a metal conductor that makes electrical contact with the microstimulator contacts and electrically surrounds the nerve.

[0071] In some variations, the microstimulator may have a bipolar stimulation current source that produce as stimulation dose with the characteristics shown in table 1, below. In some variation, the system may be configured to allow adjustment of the “Advanced Parameters” listed below; in some variations the parameters may be configured so that they are predetermined or pre-set. In some variations, the Advanced Parameters are not adjustable (or shown) to the clinician. All parameters listed in Table 1 are ±5% unless specified otherwise.

TABLE-US-00001 TABLE 1 Microstimulator parameters Property Value Default Dosage 0-5,000 μA in 25 μA steps 0 Amplitude (DA) Intervals Minute, Hour, Day, Week, Day Month Number of N = 60 Maximum 1 Doses per Interval Advanced Parameters Pulse width 50-1,000 μS in 50 μS 200 Range (PW) increments Stimulus 0.5-1000 seconds per 60 Duration (SD) dose Pulse 1-50 Hz 10 Frequency (PF) Stimulus ±3.3 or ±5.5 ±1 Volts Automatically set Voltage (SV) by software Constant ±15% over supported range Current of load impedances (200-2000 Ω) Output Specific Dose Set a specific time between Driven by default Time 12:00 am-12:00 am in one table (TBD) minute increments for each Dose Issue Number of 4 maximum 1 Sequential Dosing Programs

[0072] The Dosage Interval is defined as the time between Stimulation Doses. In some variations, to support more advanced dosing scenarios, up to four ‘programs’ can run sequentially. Each program has a start date and time and will run until the next program starts. Dosing may be suspended while the Prescription Pad is in Programming Mode. Dosing may typically continue as normal while charging. Programs may be loaded into one of four available slots and can be tested before they start running. Low, Typical, and High Dose schedules may be provided. A continuous application schedule may be available by charging every day, or at some other predetermined charging interval. For example, Table 2 illustrates exemplary properties for low, typical and high dose charging intervals:

TABLE-US-00002 TABLE 2 low typical and high dose charging intervals Property Value Low Dose Days 30 days max: 250 μA, 200 μS, 60 s, 24 hr, Charge Interval 10 Hz, ±3.3 V Typical Dose 30 days max: 1,000 μA, 200 μS, 120 s, 24 hr, Charge Interval 10 Hz, ±3.3 V High Dose Charge 3.5 days max: 5,000 μA, 500 μS, 240 s, Interval 24 hr, 20 Hz, ±5.5 V,

[0073] The system may also be configured to limit the leakage and maximum and minimum charge densities, to protect the patient, as shown in Table 3:

TABLE-US-00003 TABLE 3 safety parameters Property Value Hardware DC Leakage <50 nA Protection Maximum Charge 30 μC/cm.sup.2/phase Density Maximum Current 30 mA/cm.sup.2 Density

[0074] In some variations, the system may also be configured to allow the following functions (listed in Table 4, below):

TABLE-US-00004 TABLE 4 Additional functions of the microstimulator and/or controller(s) Function Details Charging Replenish Battery Battery Check Determine charge level System Check Self Diagnostics Relative Temperature difference from Temperature baseline Program Read/Write/Modify a dosage Management parameter programs Program Transfer entire dosage parameter Up/Download programs Electrode Bipolar Impedance (Complex) Impedances Signal Strength Strength of the charging signal to assist the patient in aligning the external Charge to the implanted Microstimulator. Patient Parameters Patient Information Patient History Limited programming and exception data Implant Time/Zone GMT + Time zone, 1 minute resolution, updated by Charger each charge session Firmware Reload Boot loader allows complete firmware reload Emergency Stop Disable dosing programs and complete power down system until Prescription Pad connected or otherwise turned off
Stimulation Reminder and/or Warning Systems and Methods

[0075] In some embodiments, the therapeutic stimulation delivered by the microstimulator can be delivered manually by the patient according to a predetermined schedule, such as a stimulation every 4, 6, 8, 12, 24, or 48 hrs. In order to improve patient compliance to the stimulation delivery schedule, a patient detectable electrical stimulation, i.e. a reminder stimulation, can be automatically delivered by the microstimulator to remind or prompt a patient to apply a manual therapeutic stimulation. The patient detectable electrical stimulation can be delivered before the scheduled therapeutic stimulation by a predetermined amount of time, such as 0 seconds to 60 minutes before the scheduled therapeutic stimulation. In some embodiments, the patient detectable electrical stimulation can have an intensity or amplitude that is large enough to be detectable but is substantially less than the therapeutic stimulation. For example, the patient detectable electrical stimulation can have an amplitude that is less than the maximum stimulation below the pain or discomfort threshold stimulation (less than or equal to 0.5 mA, e.g., 0.6 mA, 0.7 mA, 0.8 mA, 0.9 mA, etc.), and a duration of about 10 seconds or less (e.g., 9 seconds, 8 seconds, 7 seconds, 6 seconds, 5 seconds, etc.). The frequency of the stimulation may be between 0.1 Hz and 1000 Hz (e.g., between 1-100 Hz, etc.).

[0076] In some variations the patient-detectable notification stimulation may be delivered using parameters that are distinct from the therapeutic stimulation parameters. For example, if, as described above, the therapeutic stimulation parameters are electrical stimulation of the vagus nerve at between about 1.0 to 5 mA, at between about 2-90 Hz (e.g., 10 Hz) for a dose period of between 30 sec and 400 sec, then the notification stimulation may be outside of any of these ranges but the same modality as the therapeutic stimulation (e.g., electrical stimulation of the vagus nerve at less than about 1.0 mA, between about 2-90 Hz, for less than 30 sec; electrical stimulation of the vagus nerve at less than about 1.0 mA, between about 2-90 Hz, for between about 1 sec and 2 min, etc.). In some variations the notification stimulation may be pulsed with these parameters at an envelope that is between about 0.01 to 2 Hz for a duration of between about 1 sec and 1 min, where the notification stimulation is applying current at the non-therapeutic range for an on time followed by an off-time, where the frequency of on-time and/or off-time is at the envelope frequency (e.g., 0.01 to 2 Hz).

[0077] In some embodiments, the reminder stimulation can be periodically resent after the scheduled therapeutic stimulation time has elapsed if the patient has not delivered the therapeutic stimulation by the scheduled time. For example, an additional reminder stimulation can be sent every 5 to 60 minutes until the patient delivers the therapeutic stimulation. In some embodiments, the patient can elect to delay, postpone or cancel the scheduled therapeutic stimulation. In some embodiments, the reminder stimulation intensity, such as the stimulation amplitude, can be increased by a predetermined amount, such as by 0.1, 0.2, or 0.3 mA up to a predetermined maximum, with each successive reminder when the patient fails to deliver the therapeutic stimulation.

[0078] In some embodiments, the reminders can be implemented in the microstimulator hardware and/or software, such as via a program stored in memory on the microstimulator. In some embodiments, the option to delay, postpone or cancel the therapeutic stimulation can be implemented on the charger, the prescription pad, or another external control device, such as a smartphone with an application for controlling the microstimulator.

[0079] FIG. 5 is a flowchart that illustrates one embodiment of a system and method of implementing a reminder system. The reminder system can be used to provide a patient with a reminder to deliver a therapeutic stimulation using a patient controlled stimulator. The patient controlled stimulator can be a microstimulator that delivers electrical stimulation to a nerve such as the vagus nerve. In step 500, the reminder system and method can compare the current time to a programmed treatment schedule. Based on this comparison, in step 502, the system and method can determine whether the current time is within the reminder period. The reminder period can be a predetermined period of time before a scheduled therapeutic stimulation. In some embodiments, the predetermined period of time can be about 1 to 60 minutes, or about 5 to 30 minutes, or less than or equal to about 5, 10, 15, 20, 25, and 30 minutes before the schedule stimulation. In some embodiments the predetermined period of time can be adjusted by the patient and/or health care provider.

[0080] If the system and method determines that the current time is not within the reminder period, the system and method loops back again to step 500 and continues to compare the current time to the treatment schedule. In some embodiments, the system and method can perform the comparison every minute, or every 5 minutes, every 10 minutes, or at some other interval of time. If the system and method determines that the current time is within the reminder period, then it proceeds to step 504 to generate a patient detectable stimulation to remind the patient to deliver the therapeutic stimulation.

[0081] Next, in step 506, the system and method waits a predetermined period of time and in step 508 checks whether the patient has delivered the therapeutic stimulation during this predetermined period of time. If the system and method determines that the patient has not delivered the therapeutic stimulation, it loops back to step 504 to generate another patient detectable stimulation to remind the patient again to deliver the therapeutic stimulation. If the system and method determines that the patient has delivered the therapeutic stimulation, it loops back to step 500 to compare the current time to the treatment schedule to determine whether the current time is within the next reminder period.

[0082] In some embodiments, such as a VNS system that automatically delivers the VNS according to a predetermined schedule or in accordance with a stimulation algorithm, the stimulator can deliver a warning stimulation before the therapeutic stimulation is delivered automatically by the stimulator. A warning stimulation is useful in this situation because electrical stimulation of the vagus nerve can result in various side effects, such as affecting the ability to speak, altering the patient's voice, and the like. For example, providing the warning allows the patient to excuse himself or delay the scheduled stimulation if those side effects would be inconvenient at the time.

[0083] FIG. 6 is a flowchart that illustrates one embodiment of a system and method of implementing a warning system. In steps 600 and 602, the current time is compared to the treatment schedule to determine whether the current time is within a warning period preceding a scheduled therapeutic stimulation. If in step 602, it is determined that the current time is not within the warning period, the system and method loops back to step 600 to continue to compare the current time to the treatment schedule. If in step 602, it is determined that the current time is within the warning period, the system and method proceeds to step 604 to generate a patient detectable stimulation to warn the patient that therapeutic stimulation will be delivered within a predetermined period of time. The warning period can be a predetermined period of time before a scheduled therapeutic stimulation. In some embodiments, the predetermined period of time can be about 1 to 60 minutes, or about 5 to 30 minutes, or less than or equal to about 5, 10, 15, 20, 25, and 30 minutes before the schedule stimulation. In some embodiments, an additional warning period just before the therapeutic stimulation can be provided to alert the patient that a stimulation is imminent. This imminent warning period can be within 1 to 30 seconds before the stimulation is delivered. In some embodiments the predetermined period of time can be adjusted by the patient and/or health care provider.

[0084] Next, in step 606, the system and method determines whether the patient has elected to delay therapeutic stimulation. The patient can delay stimulation by, for example, selecting and/or imputing a command in a control device, such as a neck charger, a prescription pad, a mobile device, and the like that can communicate with the stimulation device. If the patient elects to delay the delivery of the therapeutic stimulation, then in step 610 the delivery of the therapeutic stimulation can be delayed by a predetermined amount of time. In some embodiments, the predetermined period of time can be about 1 to 120 minutes, or about 5 to 60 minutes. In some embodiments the predetermined period of time can be adjusted by the patient and/or health care provider. If the patient does not elect to delay the delivery of the therapeutic stimulation, then in step 608 the therapeutic stimulation is delivered to the patient and the system and method loops back to step 600 to again compare the current time to the treatment schedule to determine whether the current time is within the next warning period.

[0085] Although the patient detectable stimulations have been described as electrical stimulations, in some embodiments the patient detectable stimulation can be or include other types of stimuli, such as an audible sound, a vibration, a text message, an email, and/or a visual indicator. These other or addition stimuli can be implemented in some cases in the neurostimulator and in other cases on other devices such as a prescription pad, a wearable device on, for example, the wrist, a smartphone, and/or the charger. The alternative stimuli can be used instead of the electrical stimulation, or can be used in conjunction with the electrical stimulation, and can be used in any combination, which can be selected and modified by the patient and/or health care provider.

[0086] It is understood that this disclosure, in many respects, is only illustrative of the numerous alternative device embodiments of the present invention. Changes may be made in the details, particularly in matters of shape, size, material and arrangement of various device components without exceeding the scope of the various embodiments of the invention. Those skilled in the art will appreciate that the exemplary embodiments and descriptions thereof are merely illustrative of the invention as a whole. While several principles of the invention are made clear in the exemplary embodiments described above, those skilled in the art will appreciate that modifications of the structure, arrangement, proportions, elements, materials and methods of use, may be utilized in the practice of the invention, and otherwise, which are particularly adapted to specific environments and operative requirements without departing from the scope of the invention. In addition, while certain features and elements have been described in connection with particular embodiments, those skilled in the art will appreciate that those features and elements can be combined with the other embodiments disclosed herein.