Patent Description:
Implantable electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, deep brain stimulation systems have been used as a therapeutic modality for the treatment of Parkinson's disease, essential tremor, and the like.

Stimulators have been developed to provide therapy for a variety of treatments. A stimulator can include an implantable pulse generator (IPG), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator in the IPG generates electrical pulses that are delivered by the electrodes to body tissue.

<CIT> discloses a system for treating a patient that comprises a stimulator for stimulating brain tissue, a controller for setting stimulation parameters and a diagnostic tool for measuring patient parameters and producing diagnostic data. The stimulation parameters comprise test stimulation parameters and treatment stimulation parameters. The stimulator delivers test stimulation energy to the brain tissue based on at least one test stimulation parameter and delivers treatment stimulation energy to the brain tissue based on at least one treatment stimulation parameter. One or more treatment stimulator parameters are determined based on the diagnostic data produced by the diagnostic tool. The system is constructed and arranged to treat a neurological disease or a neurological disorder. Methods of treating a neurological disease or neurological disorder are also provided.

<CIT> discloses methods and systems for using EEG recordings to improve vagus nerve stimulation (VNS) therapy. In particular, described herein are methods and systems for using EEG recordings to detect P300 and/or activation of the nucleus basalis and/or the locus coeruleus to determine the efficacy of VNS. The EEG recordings can be used to provide feedback control to help optimize stimulation parameters and to screen for patients that respond well to VNS therapy.

<CIT> discloses a system and method for performing deep brain stimulation (DBS) therapy. The method and system include pre-operatively acquiring at least one pre-operative image of the brain with at least one imaging sub-system and determining a location of a Nucleus Basalis of Meynert (NBM) for therapy in the at least one pre-operative image, and intra-operatively acquiring at least one intra-operative image of the brain after obtaining an access opening through the skull. The method and system further provide performing surgical planning based on the pre-operative image in the intra-operative image, advancing a lead having DBS electrodes on the lead to a target position proximate to or within the NBM area, and coupling the lead to an implantable pulse generator (IPG) configured to deliver DBS pulses through the DBS electrodes to the NBM. Further, the IPG is configured to deliver DBS pulses for treating symptoms associated with Alzheimer's disease.

The present invention relates to a system for stimulation of a nucleus basalis of Meynert (NBM) of a patient according to claim <NUM> or claim <NUM>.

One aspect of the present invention is a system for stimulation of a nucleus basalis of Meynert (NBM) of a patient. The system includes an implantable electrical stimulation lead including electrodes and configured for implantation of at least one of the electrodes adjacent to or within the NBM of the patient; and an implantable pulse generator coupleable to the implantable electrical stimulation lead and configured for delivering electrical stimulation to the NBM through at least one of the electrodes of the implantable electrical stimulation lead, the implantable pulse generator including at least one processor configured to, upon user request, initially deliver a relatively low level of stimulation and to increase the level of stimulation during an initial period, which is at least <NUM> month in duration and has a start and an end, wherein the increase of the level of stimulation comprises an increase over time of at least one of a duration or an amplitude of the electrical stimulation from an initial value at the start of the initial period to a final value at the end of the initial period.

In at least some aspects, the processor is configured to deliver the electrical stimulation during the initial period with the increase of the amplitude of the electrical stimulation over time. In at least some aspects, the processor is configured to deliver the electrical stimulation during the initial period with the increase of the duration of the electrical stimulation over time. In at least some aspects, the processor is configured to deliver the electrical stimulation during the initial period with the increase of the amplitude of the electrical stimulation over time.

In at least some aspects, the increase over time of the at least one of the duration or the amplitude includes increasing the at least one of the duration or the amplitude from the initial value to the final value according to a linear ramp. In at least some aspects, the increase over time of at least one of the duration or the amplitude includes increasing the at least one of the duration or the amplitude from the initial value to the final value according to a non-linear ramp.

In at least some aspects, the processor is further configured, during the initial period, to not deliver the electrical stimulation during periods in which a cognitive load is expected for the patient. In at least some aspects, the processor is further configured to indicate to a user at least one of i) electrical stimulation is being delivered or ii) electrical stimulation is soon to be delivered, wherein the processor is further configured to provide a control for the user to postpone the delivery of the electrical stimulation and, upon actuation of the control, to postpone the delivery of the electrical stimulation.

In at least some aspects, the system further includes a sensor selected from a blood flow sensor, an electroencephalography (EEG) sensor, an electrocorticography (ECoG) sensor, a movement sensor, a chemical concentration sensor, an enzyme activity sensor, or any combination thereof, wherein the sensor is configured for monitoring response of the patient to the electrical stimulation. In at least some aspects, the processor is configured to monitor alpha wave brain activity of the patient using the EEG or ECoG sensor.

Another aspect of the present disclosure is a method for stimulating a nucleus basalis of Meynert (NBM) of a patient. The method includes implanting an electrical stimulation lead in a brain of the patient, wherein the electrical stimulation lead includes electrodes and at least one of the electrodes is disposed adjacent to or within the NBM of the patient; and delivering electrical stimulation to the NBM through at least one of the electrodes, wherein during an initial period, which is at least <NUM> month in duration and has a start and an end, at least one of a duration or an amplitude of the electrical stimulation increases over time from an initial value at the start of the initial period to a final value at the end of the initial period.

A further aspect of the present disclosure is a method for stimulating a nucleus basalis of Meynert (NBM) of a patient. The method includes implanting an electrical stimulation lead in a lateral-to-medial trajectory into a brain of the patient, wherein the electrical stimulation lead includes electrodes and at least one of the electrodes is disposed adjacent to or within the NBM of the patient; and delivering electrical stimulation to the NBM through at least one of the electrodes, wherein during an initial period, which is at least <NUM> month in duration, the electrical stimulation is not delivered during periods in which a cognitive load for the patient is expected.

In at least some aspects, the method further includes, prior to, or during, delivery of the electrical stimulation, indicating to a user that the electrical stimulation is being delivered or soon to be delivered. In at least some aspects, the method further includes, in response to user operation of a postponement control, postponing the delivery of the electrical stimulation. In at least some aspects, the method further includes, after the initial period, increasing, over time, an amount of daily time during which the electrical stimulation is delivered during the periods in which the cognitive load for the patient is expected.

In at least some aspects, the method further includes, during the initial period, increasing over time at least one of a duration or an amplitude of the electrical stimulation from an initial value at a start of the initial period to a final value at an end of the initial period. In at least some aspects, the increasing includes increasing over time the at least one of the duration or the amplitude from the initial value to the final value according to a linear ramp. In at least some aspects, the increasing includes increasing over time the at least one of the duration or the amplitude from the initial value to the final value according to a non-linear ramp.

In at least some aspects, the method further includes monitoring the patient using a sensor selected from a blood flow sensor, an electroencephalography (EEG) sensor, an electrocorticography (ECoG) sensor, a movement sensor, or any combination thereof.

Yet another aspect of the present invention is a system for stimulation of a nucleus basalis of Meynert (NBM) of a patient. The system includes an implantable electrical stimulation lead including electrodes and configured for implantation of at least one of the electrodes adjacent to or within the NBM of the patient; and an implantable pulse generator coupleable to the implantable electrical stimulation lead and configured for delivering electrical stimulation to the NBM through at least one of the electrodes of the implantable electrical stimulation lead, the implantable pulse generator including at least one processor configured to, upon user request, during an initial period, which is at least <NUM> month in duration and has a start and an end, not deliver the electrical stimulation during periods in which a cognitive load for the patient is expected.

Another aspect of the present disclosure is a method for stimulating a nucleus basalis of Meynert (NBM) of a patient. The method includes implanting an electrical stimulation lead in a brain of the patient, wherein the electrical stimulation lead includes electrodes and at least one of the electrodes is disposed adjacent to or within the NBM of the patient; delivering electrical stimulation to the NBM through at least one of the electrodes; monitoring the patient using a sensor selected from a blood flow sensor, an electroencephalography (EEG) sensor, an electrocorticography (ECoG) sensor, a movement sensor, or any combination thereof; and modifying the electrical stimulation based on the monitoring of the sensor.

In at least some aspects, monitoring the patient includes monitoring alpha wave brain activity of the patient using the EEG or ECoG sensor.

A further aspect of the present disclosure is a system for stimulation of a nucleus basalis of Meynert (NBM) of a patient. The system includes an implantable electrical stimulation lead including a plurality of electrodes and configured for implantation of at least one of the electrodes adjacent to or within the NBM of the patient; and an implantable pulse generator coupleable to the implantable electrical stimulation lead and configured for delivering electrical stimulation to the NBM through at least one of the electrodes of the implantable electrical stimulation lead. The implantable pulse generator includes at least one processor configured to deliver electrical stimulation to the NBM through at least one of the electrodes; monitor the patient using a sensor selected from a blood flow sensor, an electroencephalography (EEG) sensor, an electrocorticography (ECoG) sensor, a movement sensor, or any combination thereof; and modify the electrical stimulation based on the monitoring of the sensor.

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified.

The present disclosure is directed to the area of methods and systems for deep brain electrical stimulation. The present disclosure is also directed to methods and systems for deep brain stimulation of the nucleus basalis of Meynert (NBM).

Suitable implantable electrical stimulation systems include, but are not limited to, a least one electrical stimulation lead with one or more electrodes disposed along a distal end of the lead and one or more terminals disposed along the one or more proximal ends of the lead. Examples of electrical stimulation systems with leads are found in, for example, <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>;<CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

Turning to <FIG>, one embodiment of an electrical stimulation system <NUM> includes one or more electrical stimulation leads <NUM> and an implantable pulse generator (IPG) <NUM>. The system <NUM> can also include one or more of an external remote control (RC) <NUM>, a clinician's programmer (CP) <NUM>, an external trial stimulator (ETS) <NUM>, or an external charger <NUM>. The IPG and ETS are examples of control modules for the electrical stimulation system.

The IPG <NUM> is physically connected, optionally via one or more lead extensions <NUM>, to the electrical stimulation lead(s) <NUM>. Each electrical stimulation lead carries multiple electrodes <NUM> arranged in an array. The IPG <NUM> includes pulse generation circuitry that delivers electrical stimulation energy in the form of, for example, a pulsed electrical waveform (i.e., a temporal series of electrical pulses) to one or more electrodes <NUM> of the array in accordance with a set of stimulation parameters. The IPG <NUM> can be implanted into a patient's body, for example, below the patient's clavicle area or within the patient's abdominal cavity or at any other suitable site. The implantable pulse generator <NUM> can have multiple stimulation channels which may be independently programmable to control the magnitude of the current stimulus from each channel. In some embodiments, the implantable pulse generator <NUM> can have any suitable number of stimulation channels including, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more stimulation channels. The implantable pulse generator <NUM> can have one, two, three, four, or more connector ports, for receiving the terminals of the leads and/or lead extensions.

The ETS <NUM> may also be physically connected, optionally via the percutaneous lead extensions <NUM> and external cable <NUM>, to the stimulation leads <NUM>. The ETS <NUM>, which may have similar pulse generation circuitry as the IPG <NUM>, also delivers electrical stimulation energy in the form of, for example, a pulsed electrical waveform to the electrodes <NUM> in accordance with a set of stimulation parameters. One difference between the ETS <NUM> and the IPG <NUM> is that the ETS <NUM> is often a non-implantable device that is used on a trial basis after the electrical stimulation leads <NUM> have been implanted and prior to implantation of the IPG <NUM>, to test the responsiveness of the stimulation that is to be provided. Any functions described herein with respect to the IPG <NUM> can likewise be performed with respect to the ETS <NUM>.

The RC <NUM> may be used to telemetrically communicate with or control the IPG <NUM> or ETS <NUM> via a uni- or bi-directional wireless communications link <NUM>. Once the IPG <NUM> and electrical stimulation leads <NUM> are implanted, the RC <NUM> may be used to telemetrically communicate with or control the IPG <NUM> via a uni- or bi-directional communications link <NUM>. Such communication or control allows the IPG <NUM> to be turned on or off and to be programmed with different stimulation parameter sets. The IPG <NUM> may also be operated to modify the programmed stimulation parameters to actively control the characteristics of the electrical stimulation energy output by the IPG <NUM>. The CP <NUM> allows a user, such as a clinician, the ability to program stimulation parameters for the IPG <NUM> and ETS <NUM> in the operating room and in follow-up sessions. Alternately, or additionally, stimulation parameters can be programed via wireless communications (e.g., Bluetooth) between the RC <NUM> (or external device such as a hand-held electronic device like a mobile phone, tablet, or the like) and the IPG <NUM>.

The CP <NUM> may perform this function by indirectly communicating with the IPG <NUM> or ETS <NUM>, through the RC <NUM>, via a wireless communications link <NUM>. Alternatively, the CP <NUM> may directly communicate with the IPG <NUM> or ETS <NUM> via a wireless communications link (not shown). The stimulation parameters provided by the CP <NUM> are also used to program the RC <NUM>, so that the stimulation parameters can be subsequently modified by operation of the RC <NUM> in a stand-alone mode (i.e., without the assistance of the CP <NUM>).

Additional examples of the RC <NUM>, CP <NUM>, ETS <NUM>, and external charger <NUM> can be found in the references cited herein as well as <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>; and <CIT>.

<FIG> illustrates schematically another embodiment of an electrical stimulation system <NUM>. The electrical stimulation system includes an IPG (e.g., a control module) <NUM> and at least one electrical stimulation lead <NUM> coupleable to the IPG <NUM>. The electrical stimulation lead <NUM> includes one or more lead bodies <NUM>, an array of electrodes, such as electrode <NUM>, and an array of terminals (e.g., <NUM> in <FIG> and <FIG>) disposed along the one or more lead bodies <NUM>. In at least some embodiments, the lead is isodiametric along a longitudinal length of the lead body <NUM>. <FIG> illustrates one lead <NUM> coupled to an IPG <NUM>. Other embodiments may include two, three, four, or more leads <NUM> coupled to the IPG <NUM>.

The electrical stimulation lead <NUM> can be coupled to the IPG <NUM> in any suitable manner. In at least some embodiments, the electrical stimulation lead <NUM> couples directly to the IPG <NUM>. In at least some other embodiments, the electrical stimulation lead <NUM> couples to the IPG <NUM> via one or more intermediate devices. For example, in at least some embodiments one or more lead extensions <NUM> (see e.g., <FIG>) can be disposed between the electrical stimulation lead <NUM> and the IPG <NUM> to extend the distance between the electrical stimulation lead <NUM> and the IPG <NUM>. Lead extensions may also be useful to cross a joint or can be more easily replaced if the lead extension breaks due to fatigue as such replacement will not affect the placement of the distal end of the lead. Other intermediate devices may be used in addition to, or in lieu of, one or more lead extensions including, for example, a splitter, an adaptor, or the like or any combination thereof. It will be understood that, in the case where the electrical stimulation system <NUM> includes multiple elongated devices disposed between the electrical stimulation lead <NUM> and the IPG <NUM>, the intermediate devices may be configured into any suitable arrangement.

In <FIG>, the electrical stimulation system <NUM> is shown having a splitter <NUM> configured and arranged for facilitating coupling of the electrical stimulation lead <NUM> to the IPG <NUM>. The splitter <NUM> includes a splitter connector <NUM> configured to couple to a proximal end of the electrical stimulation lead <NUM>, and one or more splitter tails 109a and 109b configured and arranged to couple to the IPG <NUM> (or another splitter, a lead extension, an adaptor, or the like).

In at least some embodiments, the IPG <NUM> includes a connector housing <NUM> and a sealed electronics housing <NUM>. An electronic subassembly <NUM> and an optional power source <NUM> are disposed in the electronics housing <NUM>. An IPG connector <NUM> is disposed in the connector housing <NUM>. The IPG connector <NUM> is configured and arranged to make an electrical connection between the electrical stimulation lead <NUM> and the electronic subassembly <NUM> of the IPG <NUM>.

The electrodes <NUM> can be formed using any conductive, biocompatible material. Examples of suitable materials include metals, alloys, conductive polymers, conductive carbon, and the like, as well as combinations thereof. In at least some embodiments, one or more of the electrodes <NUM> are formed from one or more of: platinum, platinum iridium, palladium, palladium rhodium, or titanium. Any number of electrodes <NUM> can be used for each array <NUM>. For example, there can be two, four, six, eight, ten, twelve, fourteen, sixteen, or more electrodes <NUM>. As will be recognized, other numbers of electrodes <NUM> may also be used.

The electrodes of the one or more lead bodies <NUM> are typically disposed in, or separated by, a non-conductive, biocompatible material such as, for example, silicone, polyurethane, polyetheretherketone ("PEEK"), epoxy, and the like or combinations thereof. The lead bodies <NUM> may be formed in the desired shape by any process including, for example, molding (including injection molding), casting, and the like. The non-conductive material typically extends from the distal end of the one or more lead bodies <NUM> to the proximal end of each of the one or more lead bodies <NUM>.

Terminals (e.g., <NUM> in <FIG> and <FIG>) are typically disposed along the proximal end of the one or more lead bodies <NUM> of the electrical stimulation system <NUM> (as well as any splitters, lead extensions, adaptors, or the like) for electrical connection to corresponding connector contacts (e.g., <NUM> in <FIG> and <NUM> in <FIG>). The connector contacts are disposed in connectors (e.g., <NUM> in <FIG>; and <NUM> in <FIG>) which, in turn, are disposed on, for example, the IPG <NUM> (or a lead extension, a splitter, an adaptor, or the like). Electrically conductive wires, cables, or the like (not shown) extend from the terminals to the electrodes <NUM>. Typically, one or more electrodes <NUM> are electrically coupled to each terminal. In at least some embodiments, each terminal is only connected to one electrode <NUM>.

The electrically conductive wires ("conductors") may be embedded in the non-conductive material of the lead body <NUM> or can be disposed in one or more lumens (not shown) extending along the lead body <NUM>. In some embodiments, there is an individual lumen for each conductor. In other embodiments, two or more conductors extend through a lumen. There may also be one or more lumens (not shown) that open at, or near, the proximal end of the lead body <NUM>, for example, for inserting a stylet to facilitate placement of the lead body <NUM> within a body of a patient. Additionally, there may be one or more lumens (not shown) that open at, or near, the distal end of the lead body <NUM>, for example, for infusion of drugs or medication into the site of implantation of the one or more lead bodies <NUM>. In at least some embodiments, the one or more lumens are permanently or removably sealable at the distal end.

<FIG> is a schematic side view of one embodiment of a proximal end of one or more elongated devices <NUM> configured and arranged for coupling to one embodiment of the IPG connector <NUM>. The one or more elongated devices may include, for example, the lead body <NUM>, one or more intermediate devices (e.g., the splitter <NUM> of <FIG>, the lead extension <NUM> of <FIG>, an adaptor, or the like or combinations thereof), or a combination thereof. <FIG> illustrates two elongated devices <NUM> coupled to the IPG <NUM>. These two elongated devices <NUM> can be two tails as illustrated in <FIG> or two different leads or any other combination of elongated devices.

The IPG connector <NUM> defines at least one port into which a proximal end of the elongated device <NUM> can be inserted, as shown by directional arrows 212a and 212b. In <FIG> (and in other figures), the connector housing <NUM> is shown having two ports 204a and 204b. The connector housing <NUM> can define any suitable number of ports including, for example, one, two, three, four, five, six, seven, eight, or more ports.

The IPG connector <NUM> also includes a plurality of connector contacts, such as connector contact <NUM>, disposed within each port 204a and 204b. When the elongated device <NUM> is inserted into the ports 204a and 204b, the connector contacts <NUM> can be aligned with a plurality of terminals <NUM> disposed along the proximal end(s) of the elongated device(s) <NUM> to electrically couple the IPG <NUM> to the electrodes (<NUM> of <FIG>) disposed at a distal end of the electrical stimulation lead <NUM>. Examples of connectors in IPGs are found in, for example, <CIT> and <CIT>.

<FIG> is a schematic side view of another embodiment of the electrical stimulation system <NUM>. The electrical stimulation system <NUM> includes a lead extension <NUM> that is configured and arranged to couple one or more elongated devices <NUM> (e.g., the lead body <NUM>, the splitter <NUM>, an adaptor, another lead extension, or the like or combinations thereof) to the IPG <NUM>. In <FIG>, the lead extension <NUM> is shown coupled to a single port <NUM> defined in the IPG connector <NUM>. Additionally, the lead extension <NUM> is shown configured and arranged to couple to a single elongated device <NUM>. In alternate embodiments, the lead extension <NUM> is configured and arranged to couple to multiple ports <NUM> defined in the IPG connector <NUM>, or to receive multiple elongated devices <NUM>, or both.

A lead extension connector <NUM> is disposed on the lead extension <NUM>. In <FIG>, the lead extension connector <NUM> is shown disposed at a distal end <NUM> of the lead extension <NUM>. The lead extension connector <NUM> includes a connector housing <NUM>. The connector housing <NUM> defines at least one port <NUM> into which terminals <NUM> of the elongated device <NUM> can be inserted, as shown by directional arrow <NUM>. The connector housing <NUM> also includes a plurality of connector contacts, such as connector contact <NUM>. When the elongated device <NUM> is inserted into the port <NUM>, the connector contacts <NUM> disposed in the connector housing <NUM> can be aligned with the terminals <NUM> of the elongated device <NUM> to electrically couple the lead extension <NUM> to the electrodes (<NUM> of <FIG>) disposed along the lead (<NUM> in <FIG>).

In at least some embodiments, the proximal end of the lead extension <NUM> is similarly configured and arranged as a proximal end of the lead <NUM> (or other elongated device <NUM>). The lead extension <NUM> may include a plurality of electrically conductive wires (not shown) that electrically couple the connector contacts <NUM> to a proximal end <NUM> of the lead extension <NUM> that is opposite to the distal end <NUM>. In at least some embodiments, the conductive wires disposed in the lead extension <NUM> can be electrically coupled to a plurality of terminals (not shown) disposed along the proximal end <NUM> of the lead extension <NUM>. In at least some embodiments, the proximal end <NUM> of the lead extension <NUM> is configured and arranged for insertion into a connector disposed in another lead extension (or another intermediate device). In other embodiments (and as shown in <FIG>), the proximal end <NUM> of the lead extension <NUM> is configured and arranged for insertion into the IPG connector <NUM>.

Returning to <FIG>, in at least some embodiments at least some of the stimulation electrodes take the form of segmented electrodes that extend only partially around the perimeter (for example, the circumference) of the lead. These segmented electrodes can be provided in sets of electrodes, with each set having electrodes circumferentially distributed about the lead at a particular longitudinal position.

In <FIG>, the electrodes <NUM> are shown as including both ring electrodes <NUM> and segmented electrodes <NUM>. In some embodiments, the electrodes <NUM> are all segmented electrode or all ring electrodes. The segmented electrodes <NUM> of <FIG> are in sets of three (one of which is not visible in <FIG>), where the three segmented electrodes of a particular set are electrically isolated from one another and are circumferentially offset along the lead <NUM>. Any suitable number of segmented electrodes can be formed into a set including, for example, two, three, four, or more segmented electrodes. The lead <NUM> of <FIG> has thirty segmented electrodes <NUM> (ten sets of three electrodes each) and two ring electrodes <NUM> for a total of <NUM> electrodes <NUM>.

Segmented electrodes can be used to direct stimulus current to one side, or even a portion of one side, of the lead. When segmented electrodes are used in conjunction with an implantable pulse generator that delivers multiple current stimuli simultaneously, current steering can be achieved to deliver the stimulus more precisely to a position around an axis of the lead (i.e., radial positioning around the axis of the lead). Segmented electrodes may provide for superior current steering than ring electrodes because target structures in deep brain stimulation are not typically symmetric about the axis of the distal electrode array. Instead, a target may be located on one side of a plane running through the axis of the lead. Through the use of a segmented electrode array, current steering can be performed not only along a length of the lead but also around a perimeter of the lead. This provides precise three-dimensional targeting and delivery of the current stimulus to neural target tissue, while potentially avoiding stimulation of other tissue.

<FIG> illustrates a <NUM>-electrode lead <NUM> with a lead body <NUM> and two ring electrodes <NUM> proximal to thirty segmented electrodes <NUM> arranged in ten sets of three segmented electrodes each. In the illustrated embodiments, the ring electrodes <NUM> are proximal to the segmented electrodes <NUM>. In other embodiments, one or more of the ring electrodes <NUM> can be proximal to, or distal to, one or more of the segmented electrodes <NUM>.

Any number of segmented electrodes <NUM> may be disposed on the lead body including, for example, one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, twenty, twenty-four, twenty-eight, thirty, thirty-two, or more segmented electrodes <NUM>. It will be understood that any number of segmented electrodes <NUM> may be disposed along the length of the lead body. A segmented electrode <NUM> typically extends only <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or less around the circumference of the lead.

The segmented electrodes <NUM> may be grouped into sets of segmented electrodes, where each set is disposed around a circumference of the electrical stimulation lead <NUM> at a particular longitudinal portion of the electrical stimulation lead <NUM>. The electrical stimulation lead <NUM> may have any number of segmented electrodes <NUM> in a given set of segmented electrodes. The electrical stimulation lead <NUM> may have one, two, three, four, five, six, seven, eight, or more segmented electrodes <NUM> in a given set. The electrical stimulation lead <NUM> may have any number of sets of segmented electrodes including, but not limited to, one, two, three, four, five, six, eight, ten, twelve, fifteen, sixteen, twenty, or more sets. The segmented electrodes <NUM> may be uniform, or vary, in size and shape. In some embodiments, the segmented electrodes <NUM> are all of the same size, shape, diameter, width or area or any combination thereof. In some embodiments, the segmented electrodes <NUM> of each circumferential set (or even all segmented electrodes disposed on the lead <NUM>) may be identical in size and shape.

Each set of segmented electrodes <NUM> may be disposed around the circumference of the lead body to form a substantially cylindrical shape around the lead body. The spacing between individual electrodes of a given set of the segmented electrodes may be the same, or different from, the spacing between individual electrodes of another set of segmented electrodes on the electrical stimulation lead <NUM>. In at least some embodiments, equal spaces, gaps, or cutouts are disposed between each segmented electrode <NUM> around the circumference of the lead body. In other embodiments, the spaces, gaps, or cutouts between the segmented electrodes <NUM> may differ in size or shape. In other embodiments, the spaces, gaps, or cutouts between segmented electrodes <NUM> may be uniform for a particular set of the segmented electrodes <NUM>, or for all sets of the segmented electrodes <NUM>. The sets of segmented electrodes <NUM> may be positioned in irregular or regular intervals along a length of the lead body.

<FIG> illustrate other embodiments of leads with segmented electrodes <NUM>. <FIG> illustrates a sixteen electrode lead <NUM> having one ring electrode <NUM> that is proximal to five sets of three segmented electrodes <NUM> each. <FIG> illustrates a sixteen electrode lead <NUM> having eight sets of two segmented electrodes <NUM> each. As illustrated in <FIG>, an embodiment of a lead <NUM> does not necessarily include a ring electrode. <FIG> illustrates a sixteen electrode lead <NUM> having four ring electrodes <NUM> that are proximal to six sets of two segmented electrodes <NUM> each. <FIG> illustrates a thirty-two electrode lead <NUM> having sixteen sets of two segmented electrodes <NUM> each (for clarity of illustration, not all of the electrodes are shown). It will be recognized that any other electrode combination of ring electrodes, segmented electrodes, or both types of electrodes can be used.

When the lead <NUM> includes both ring electrodes <NUM> and segmented electrodes <NUM>, the ring electrodes <NUM> and the segmented electrodes <NUM> may be arranged in any suitable configuration. For example, when the lead <NUM> includes two or more ring electrodes <NUM> and one or more sets of segmented electrodes <NUM>, the ring electrodes <NUM> can flank the one or more sets of segmented electrodes <NUM>. Alternately, the two or more ring electrodes <NUM> can be disposed proximal to the one or more sets of segmented electrodes <NUM> or the two or more ring electrodes <NUM> can be disposed distal to the one or more sets of segmented electrodes <NUM> or any other suitable arrangement of the ring electrodes <NUM> and segmented electrodes <NUM>.

The electrodes <NUM>, <NUM> may have any suitable longitudinal length including, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. The longitudinal spacing between adjacent electrodes <NUM>, <NUM> may be any suitable amount including, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, where the spacing is defined as the distance between the nearest edges of two adjacent electrodes. In some embodiments, the spacing is uniform between longitudinally adjacent of electrodes along the length of the lead. In other embodiments, the spacing between longitudinally adjacent electrodes may be different or non-uniform along the length of the lead.

Examples of electrical stimulation leads with segmented electrodes include <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>. An electrical stimulation lead may also include a tip electrode and examples of leads with tip electrodes include at least some of the previously cited references, as well as <CIT> and <CIT>. A lead with segmented electrodes may be a directional lead that can provide stimulation in a particular direction using the segmented electrodes.

<FIG> is a schematic overview of one embodiment of components of an electrical stimulation system <NUM> including an electronic subassembly <NUM> disposed within an IPG. It will be understood that the electrical stimulation system can include more, fewer, or different components and can have a variety of different configurations including those configurations disclosed in the stimulator references cited herein.

Some of the components (for example, power source <NUM>, antenna <NUM>, receiver <NUM>, processor <NUM>, and memory <NUM>) of the electrical stimulation system can be positioned on one or more circuit boards or similar carriers within a sealed housing of an implantable pulse generator, if desired. Any power source <NUM> can be used including, for example, a battery such as a primary battery or a rechargeable battery. Examples of other power sources include super capacitors, nuclear or atomic batteries, mechanical resonators, infrared collectors, thermally-powered energy sources, flexural powered energy sources, bioenergy power sources, fuel cells, bioelectric cells, osmotic pressure pumps, and the like including the power sources described in <CIT>.

As another alternative, power can be supplied by an external power source through inductive coupling via the optional antenna <NUM> or a secondary antenna. The external power source can be in a device that is mounted on the skin of the user or in a unit that is provided near the user on a permanent or periodic basis.

If the power source <NUM> is a rechargeable battery, the battery may be recharged using the optional antenna <NUM>, if desired. Power can be provided to the battery for recharging by inductively coupling the battery through the antenna to a recharging unit <NUM> external to the user. Examples of such arrangements can be found in the references identified above.

In one embodiment, electrical current is emitted by the electrodes <NUM> on the lead body to stimulate nerve fibers, muscle fibers, or other body tissues near the electrical stimulation system. A processor <NUM> is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor <NUM> can, if desired, control one or more of the timing, frequency, amplitude, width, and waveform of the pulses. In addition, the processor <NUM> can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor <NUM> may select which electrode(s) are cathodes and which electrode(s) are anodes and the amount of anodic or cathodic current assigned to each. In some embodiments, the processor <NUM> may be used to identify which electrodes provide the most useful stimulation of the desired tissue. Instructions for the processor <NUM> can be stored on the memory <NUM>.

Any processor can be used and can be as simple as an electronic device that, for example, produces pulses at a regular interval or the processor can be capable of receiving and interpreting instructions from the CP/RC <NUM> (such as CP <NUM> or RC <NUM> of <FIG>) that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor <NUM> is coupled to a receiver <NUM> which, in turn, is coupled to the optional antenna <NUM>. This allows the processor <NUM> to receive instructions from an external source to, for example, direct the pulse characteristics and the selection of electrodes, if desired.

In one embodiment, the antenna <NUM> is capable of receiving signals (e.g., RF signals) from a CP/RC <NUM> (see, CP <NUM> or RC <NUM> of <FIG>) which is programmed or otherwise operated by a user. The signals sent to the processor <NUM> via the antenna <NUM> and receiver <NUM> can be used to modify or otherwise direct the operation of the electrical stimulation system. For example, the signals may be used to modify the pulses of the electrical stimulation system such as modifying one or more of pulse width, pulse frequency, pulse waveform, and pulse amplitude. The signals may also direct the electrical stimulation system <NUM> to cease operation, to start operation, to start charging the battery, or to stop charging the battery. In other embodiments, the stimulation system does not include an antenna <NUM> or receiver <NUM> and the processor <NUM> operates as programmed.

Optionally, the electrical stimulation system <NUM> may include a transmitter (not shown) coupled to the processor <NUM> and the antenna <NUM> for transmitting signals back to the CP/RC <NUM> or another unit capable of receiving the signals. For example, the electrical stimulation system <NUM> may transmit signals indicating whether the electrical stimulation system <NUM> is operating properly or not or indicating when the battery needs to be charged or the level of charge remaining in the battery. The processor <NUM> may also be capable of transmitting information about the pulse characteristics so that a user or clinician can determine or verify the characteristics.

Dementias like Alzheimer's disease are generally associated with the reduction of a key neurotransmitter, Acetylcholine (Ach), in the cortex. Studies suggest that anticholinergic medications (for other health issues) are associated with an increased likelihood of dementia, and one of the FDA approved classes of drugs for dementia is an anticholinesterase (i.e., a drug to slow metabolism of ACh so that it can have a longer/stronger effect).

The cells that produce ACh and send and release it in the cortex are located in the nucleus basalis of Meynert (NBM). It is thought that stimulation of this region can evoke a release of ACh in the cortex and counteract effects of dementia. The release of ACh may also be used to treat depression and neuropsychological disorders. It has been demonstrated that in non-human primates stimulation of the NBM notably improves performance in a memory task. It has also been shown that an intermittent stimulation protocol is effective, but that a continuous stimulation protocol is not effective, perhaps because synaptic machinery is overworked.

In addition to stimulating the NBM neurons to deliver more ACh, it is desirable to also slow or halt the neurodegeneration of those cells.

The NBM has a unique, curved shape that may be characterized as a bent oval pancake or a flat banana. An approximation of the shape of the NBM <NUM> of one hemisphere of the brain is illustrated in <FIG>. The shape can make the NBM <NUM> difficult to fully engage using an electrical stimulation lead as it may be difficult for one electrode array to stimulate a relatively large portion, or even all, of the cells to take full advantage of the ACh machinery of each cell.

In at least some embodiments, to address the unique shape of the target NBM <NUM> and to stimulate more of the target NBM, multiple electrical stimulation leads <NUM> can be placed at different parts of the target NBM <NUM>, and stimulation can be cycled between the electrodes <NUM> of the electrical stimulation leads <NUM> to produce multiple stimulation regions <NUM>, as illustrated in <FIG>. In the illustrated embodiment of <FIG>, two electrical stimulation leads <NUM> are implanted using a superior-to-inferior trajectory and one electrical stimulation lead is used to produce two different stimulation regions <NUM> and the other electrical stimulation lead provides another stimulation region.

In at least some embodiments, as illustrated in <FIG>, to address the unique shape of the target NBM <NUM>, to stimulate more of the target, at least one stimulation lead <NUM> can be implanted along a lead trajectory that is generally or approximately (for example, within <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees) oriented lateral-to-medial, rather than the typical superior-to-inferior, to align electrodes <NUM> of the lead along or adjacent the axis of the target NBM <NUM>. Along this lead trajectory, more electrodes <NUM> from a single electrical stimulation lead <NUM> can be near (including traversing) portions of the target NBM <NUM> to produce multiple stimulation regions <NUM> which can be cycled through as described in more detail below.

Any suitable number of electrical stimulation leads <NUM> can be used to stimulate the NBM including, but not limited to, one, two, three, four, or more leads. When multiple electrical stimulation leads <NUM> are used, there can be any suitable combination of electrical stimulation lead(s) <NUM> implanted in the superior-to-inferior trajectory (<FIG>) and lead(s) implanted in the lateral-to-medial trajectory (<FIG>). Electrical stimulation lead(s) <NUM> can be implanted in one or both hemispheres of the brain to stimulate one or both NBMs <NUM>. The arrangement of electrical stimulation lead(s) <NUM> for each hemisphere can be the same or different.

An electrical stimulation lead <NUM> can produce any suitable number of stimulation regions <NUM> including, but not limited to, one, two, three, four, or more stimulation regions. In at least some embodiments, one or more electrical stimulation leads <NUM> include segmented electrodes <NUM>. The use of segmented electrodes <NUM> may facilitate the selection of directionality of the stimulation regions <NUM>.

One or more electrodes <NUM> can be used to generate the electrical stimulation for a stimulation region <NUM>. The electrode(s) can be cathodes or anodes or any combination thereof. In at least some embodiments, the sealed electronics housing <NUM> (or other portion of the case) of the IPG <NUM> can be used as a return electrode, which is often the case for monopolar electrical stimulation. Multipolar electrical stimulation can also be used. In at least some embodiments, the electrical stimulation is anodic stimulation (e.g., where the active electrode(s) are anodes), which is often more effective for selective stimulation of cell bodies than cathodic stimulation.

Producing a combination of stimulation regions <NUM> may facilitate effective stimulation of a relatively large part, or even all, of the NBM <NUM>. The stimulation regions <NUM> illustrated in <FIG> correspond to the estimated effective regions of stimulation for a particular set of stimulation parameters. Examples of stimulation parameters include, but are not limited to, selection of electrode(s), stimulation amplitude (which can be independent for each electrode), pulse frequency, pulse duration or width, or the like. In at least some embodiments, the stimulation regions <NUM> of <FIG> can be determined or estimated algorithmically or manually. The terms "stimulation field map" (SFM), "volume of activation" (VOA), or "volume of tissue activated (VTA)" are often used to designate the estimated stimulation region <NUM> of tissue that will be stimulated for a particular set of stimulation parameters. Any suitable method for determining the VOA/SFM/VTA can be used including those described in, for example, <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT> and <CIT>.

In at least some embodiments, using electrodes of the same or different electrical stimulation leads, multiple stimulation regions <NUM> are chosen so that the combination of these stimulation regions can cover much of the target NBM <NUM>. Any suitable number of stimulation regions <NUM> can be used including, but not limited to, one, two, three, four, five, six, eight, ten, twelve, or more stimulation regions. In at least some embodiments, the stimulation regions <NUM> may also be chosen to limit or avoid overlap between stimulation regions.

In at least some embodiments, the selection of multiple stimulation regions <NUM> (for example, SFMs) can be based on post-op radiography, an MRI, or any other imaging technique or any combination thereof. In at least some embodiments, the selection of multiple stimulation regions <NUM> (for example, SFMs) can be based on a surgical plan, alone or in combination with post-op imaging. In at least some embodiments, the selection of multiple stimulation regions <NUM> (for example, SFMs) is performed offline.

In at least some embodiments, the selection of multiple stimulation regions <NUM> (for example, SFMs) can be performed manually using a user interface of a programmer or other device that enables display of multiple stimulation regions simultaneously. In at least some embodiments, the selection of multiple stimulation regions <NUM> (for example, SFMs)can be performed algorithmically by using techniques, such as, for example, binary search, gradient descent searches, genetic or particle swarm searches, or the like or any combination thereof.

In at least some embodiments, the stimulation regions <NUM> are chosen based on scoring or other criteria that increases based on the amount of the NBM <NUM> is covered by the stimulation regions or penalizes for portions of the target NBM <NUM> that are not covered by the stimulation regions. In at least some embodiments, the stimulation regions <NUM> the scoring criteria penalizes for overlap between stimulation regions. In at least some embodiments, the scoring criteria may be weighted for the overlap or non-stimulation regions. Examples of scoring and scoring criteria can be found at, for example, <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

The delivery of electrical stimulation to the stimulation regions can include additional stimulation parameters beyond amplitude, pulse width, pulse frequency, and the like. Examples of additional stimulation parameters include, but are not limited to, duty cycle ratio, duration of a stimulation cycle, total number of pulses in a stimulation period, duration of a stimulation period, number of stimulation periods a day, or the like or any combination thereof. The delivery of stimulation to the stimulation region can be described in a series of cycles with stimulation during a portion of the cycle and no stimulation during another portion of the cycle. The duty cycle ratio can be equal to the ratio of the time during which stimulation is provided to the time during which no stimulation is provided. For example, a <NUM> second cycle may include <NUM> seconds of stimulation and <NUM> seconds of no stimulation resulting in a stimulation duty cycle ratio of <NUM>:<NUM>. The duration of the cycle can be any suitable number including, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> seconds or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> minutes or more, or the like. The duty cycle ratio can be any suitable ratio including, but not limited to, a ratio in a range from <NUM>:<NUM> to <NUM>:<NUM> or from <NUM>:<NUM> to <NUM>:<NUM> or from <NUM>:<NUM> to <NUM>:<NUM>.

The stimulation period can be defined as the period of time when multiple cycles of stimulation are performed. The duration of the stimulation period can be any suitable number including, but not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> minutes or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> hours or more. In at least some embodiments, the duration of the stimulation period may be defined as a number of pulses instead or, or in addition to, a period of time. The number of pulses in a stimulation period can be any suitable number and, at least in some embodiments, can be in a range of <NUM>,<NUM> to <NUM>,<NUM> or in a range of <NUM>,<NUM> to <NUM>,<NUM> or in a range of <NUM>,<NUM> to <NUM>,<NUM>.

The number of stimulation periods per day can be any suitable number including, but not limited to, one, two, three, four, five, six, eight, ten, twelve, <NUM>, <NUM>, or more. In at least some embodiments, the number of stimulation periods per day or the number or stimulation pulses delivered per day may be considered a "dose". As an example, stimulation to one of the stimulation regions <NUM> can be delivered at a pulse rate of <NUM> during <NUM> seconds of a <NUM> second cycle (for a duty cycle ratio of <NUM>:<NUM>) for a stimulation period of <NUM> minutes (i.e., <NUM> cycles) with one stimulation period per day (for a total of <NUM>,<NUM> stimulation pulses per day).

In at least some embodiments, the stimulation regions <NUM> are stimulated for the same or similar amounts of time during a cycle or a stimulation period. In other embodiments, there may be a different amount of stimulation time (e.g., different amount of time for a cycle or a stimulation period) for different stimulation regions <NUM>.

When multiple stimulation regions <NUM> are to be stimulated, in at least some embodiments, the stimulation of each of the stimulation regions <NUM> can be performed using temporal offsets. In at least some embodiments, the delivery of stimulation may be interleaved. For example, one stimulation region can be stimulated followed by another and so on. For example, during a <NUM> second cycle stimulation is delivered to first stimulation region for <NUM> seconds, then to a second stimulation region for <NUM> seconds, and then to third stimulation region for <NUM> seconds. Thus, each stimulation region is stimulated at a duty cycle ratio of <NUM>:<NUM>. In this example, overlap between the three stimulation regions is preferably relatively small or zero.

As another example, the cycles can be interleaved so that during the first <NUM> second cycle stimulation is delivered to first stimulation region for <NUM> seconds, then for a second <NUM> second cycle stimulation is delivered to a second stimulation region for <NUM> seconds, and then for a third <NUM> second cycle stimulation is delivered to third stimulation region for <NUM> seconds. In this example, overlap between the three stimulation regions may be less important because <NUM> seconds of each <NUM> second period has no stimulation at all.

In other embodiments, the stimulation periods for at least some stimulation regions <NUM> are performed sequentially. For example, during a first stimulation period the first stimulation region is stimulated, then for a second stimulation period the second stimulation region is stimulated, and then for a third stimulation period the third stimulation region is stimulated. For example, the first stimulation region can be stimulated for one three hour stimulation period, followed by the second stimulation region being stimulated for a second three hour stimulation period, and then followed by the third stimulation region being stimulated for a third stimulation period.

These arrangements avoid continual stimulation of the stimulation regions <NUM> as it is believed that periodic stimulation is more beneficial. In at least some embodiments, more than one stimulation region <NUM> can be stimulated at any given period of time and, preferably, stimulation regions <NUM> that are simultaneously stimulated do not overlap and are more preferably separated from each other by at least <NUM> to <NUM> millimeter.

In at least some embodiments, the delivery of stimulation may be performed automatically using stimulation settings programmed by a clinician or other caregiver. In at last some embodiments, the delivery of stimulation may be initiated manually by a patient, clinician, or other caregiver. In at least some embodiments, the automated delivery of stimulation may be supplemented or replaced by manual initiation of stimulation. In at least some embodiments, a system may limit the manual initiation of stimulation by a patient, clinician, or other caregiver to number of stimulation periods that can be delivered in a day, or a week, or other defined period of time.

In at least some embodiments, a patient, clinician, or other caregiver can initiate a bolus of therapeutic stimulation from an external device (such as RC <NUM> or CP <NUM>) at a time that is convenient. In at least some embodiments, the electrical stimulation system <NUM> can be configured to only allow the patient to initiate a prescribed number of boluses per unit time (e.g., day or week). In at least some embodiments, the electrical stimulation system <NUM> includes an external device (such as RC <NUM> or CP <NUM>) that when connected to the IPG <NUM> will reflect a warning if the patient has not initiated a predetermined or suitable number of therapy sessions. In at least some embodiments, this data or warning may be sent to a clinician or other caregiver, so that they can respond.

In at least some embodiments, the system or method allows the patient, clinician, or a caregiver the ability to postpone stimulation. In at least some embodiments, the system (for example, the IPG <NUM>, RC <NUM>, CP <NUM>, or another device) may alert a patient, clinician, or caregiver that stimulation is being delivered or is about to be delivered using an external device (for example, RC <NUM>, CP <NUM>, a mobile phone, or the like). In at least some embodiments, the patient, clinician, or a caregiver can use the external device to postpone stimulation. In at least some embodiments, the external device includes at least one control that permits stimulation to be postponed for a period of time (for example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> minutes or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> hours or <NUM> day or more or any other suitable period of time.

In at least some embodiments, stimulation may have a detrimental effect on the memory or cognitive ability of the patient during the period of stimulation. In at least some embodiments, the electrical stimulation system <NUM> can be programmed to deliver stimulation at night (or other periods of time) when the patient is likely asleep. In at least some embodiments, the electrical stimulation system <NUM> or IPG <NUM> is configured to track the time of day and can be programmed to deliver stimulation at night (or other periods of time) when the patient is likely asleep. In at least some embodiments, the electrical stimulation system <NUM> or IPG <NUM> can be coupleable to an external or implantable sensor <NUM> (for example, a heart rate, respiration, posture, accelerometer, or biomarker sensor) or device that contains a sensor <NUM> (for example, a mobile phone or fitness tracker) that can provide information about the state of the patient to determine or estimate whether the patient is awake or asleep. The IPG <NUM> may be configured to provide stimulation only when the IPG or electrical stimulation system <NUM> determines (or receives information from an external sensor <NUM> or device that contains a sensor <NUM>) that the patient is asleep. In at least some embodiments, the IPG <NUM> or electrical stimulation system <NUM> may determine, estimate, or receiving information from an external device regarding a sleep stage (for example, REM sleep) of the patient and provide stimulation only during one or more selected or specified sleep stages.

In some embodiments, the electrical stimulation system <NUM> or IPG <NUM> can be configured with "daytime" or "awake" stimulation parameters and with "nighttime" or "asleep" stimulation parameters, and can use a clock or any of the other approaches described above to determine which should be used when a period of stimulation is initiated.

In at least some embodiments, the detrimental effect on the memory or cognitive ability is reduced with cessation of stimulation and may improve over time after the cessation of stimulation. In at least some embodiments, the detrimental effect on the memory or cognitive ability of the patient during stimulation decreases over time. Although the methods and systems described herein are not dependent on any particular theory, it is thought that the brain or NBM may become more accustomed to stimulation over time. In at least some embodiments, cognitive performance concurrent with stimulation improves over an acclimation period (which may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> days or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> months or <NUM> year or more or any other suitable time period. ) The acclimation period may vary between individuals, may vary with implantation site or arrangement, or may vary depending on the stimulation parameters or amount of stimulation, or the like or any combination thereof.

In at least some embodiments, the system or method can be configured to initially deliver stimulation during times when a cognitive load is not expected to be needed. The term "cognitive load" refers to period of time in which the patient is actively using their mental faculties and working memory including, but not limited to, periods of time in which the patient is performing tasks for work (professional or at home), recreation, or hobbies; driving; reading; teaching; learning; performing tasks that require mental focus; or the like. Instances in which a cognitive load is not expected to be needed include, but are not limited to, sleeping, resting, watching television, listening to music, or the like. In at least some embodiments, the patient, user, clinician, programmer, or any other suitable individual (or multiple individuals) can program the system to define what activities are not expected to need a cognitive load or what activities do need a cognitive load or any combination thereof.

In at least some embodiments, this behavior of the system or method can be change over time so that the stimulation can be delivered during times of cognitive load. In at least some embodiments, the change can be automatic or can be initiated manually or both options can be present. In at least some embodiments, the change can be gradual with increasing amounts of time during which the stimulation is delivered during times of cognitive load.

In at least some embodiments, the methods or systems can initially deliver a relatively low level of stimulation (e.g., a relatively low amplitude, a relatively low duration, or the like or any combination thereof. ) In at least some embodiments, the relatively low level of stimulation can reduce or eliminate the detrimental effect on the memory or cognitive ability during stimulation. Over time, the level of stimulation can be increased or ramped up. For example, the amplitude, duration, or the like or any combination thereof can be increased or ramped up over time (for example, over a period of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> days or <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> months or <NUM> year or more or any other suitable time period. ) In at least some embodiments, the final amplitude or final duration is at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> times larger than the initial amplitude or initial duration.

Although the methods and systems described herein are not dependent on any particular theory, it is thought that the brain can become accustomed to receiving stimulation during this period of increasing or ramping up stimulation. In at least some embodiments, parameters of the increase or ramp (for example, starting intensity or amplitude, ending intensity or amplitude, starting duration (e.g., a starting daily duration), ending duration (e.g., an ending daily duration), duration of the time period, the type of increase or ramp - such as linear, non-linear, stepped, exponential, or the like or any combination) can be selected or programmable by a clinician or other individual. In at least some embodiments, the ramp can include increasing intensity, increasing duration (e.g., increasing daily duration), or any combination thereof.

In at least some embodiments, a system or method can include or utilize one or more sensors <NUM> (<FIG>) to detect when stimulation evokes a physiological response. Examples of suitable sensors <NUM> include, but are not limited to, a blood flow sensor (for example, an implantable or external blood flow sensor), an electrocorticography (ECoG) sensor (for example, an implantable ECoG sensor which can be implanted, for example, over the cortex at the time the lead is placed), an electroencephalography (EEG) sensor (for example, an external or implantable EEG sensor), a movement sensor (for example, at least one accelerometer, gyroscope, a chemical concentration sensor, an enzyme activity sensor, or the like or any combination thereof) which may be internal or on an external device (for example, a phone, watch, exercise monitor, or the like). A ECoG or EEG sensor can be used to detect changes in brain activity, such as alpha wave brain activity (for example, brain activity in the range of <NUM> to <NUM>). A movement sensor can be used to detect changes in activity level, such as an increase or decrease of activity.

In at least some embodiments, the measurements of the sensor(s) <NUM> are used to determine or modify stimulation parameters, to aid in surgical implantation, or to aid in system programming. In at least some embodiments, the measurements of the sensor(s) <NUM> are used to modulate therapy for the patient (for example, to evoke a physiological response at a certain level, to evoke a physiological response a certain number of times per day or per specified period, to measure a rate of the response to determine or modify appropriate therapy, or the like or any combination thereof.

In at least some embodiments, the implantable pulse generator (such as IPG <NUM>) receives the measurements of the sensor(s) <NUM> and can determine or modify the stimulation parameters based on the measurements or modulate the therapy based on the measurements. In at least some embodiments, an external device (such as RC <NUM>, CP <NUM>, a mobile phone, a computer, or the like or any combination) receives the measurements of the sensor(s) and can determine or modify the stimulation parameters based on the measurements or modulate the therapy based on the measurements and then communicate the stimulation parameters or the modulate therapy to the implantable pulse generator.

Additionally or alternatively, optical stimulation of the NBM may be performed. In at least some embodiments, the delivery of light to the NBM may mitigate neurodegeneration. Examples of optical stimulation systems (at least some of which also produce electrical stimulation, e.g., electro-optical stimulation systems) with optical or electro-optical stimulation leads are found in, for example, <CIT> and <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

<FIG> illustrate optical stimulation leads <NUM> (or electro-optical lead in <FIG> with optional electrodes <NUM>) with light delivery elements <NUM> that produce stimulation light <NUM> to stimulate the target NBM <NUM>. The electrical stimulation components described above, and illustrated in <FIG>, can be used or adapted for use in optical or electro-optical stimulation systems, as further described in the references cited above.

Examples of light delivery elements <NUM> include, but are not limited to, light emitting diodes (LEDs), laser diodes, or a fiber optic coupled to a light source (such as an LED or laser diode). In <FIG>, the light delivery element <NUM> can be a combination of multiple light delivery elements.

Any suitable number of leads <NUM> can be used to stimulate the NBM including, but not limited to, one, two, three, four, or more leads. When multiple leads <NUM> are used, there can be any suitable combination of lead(s) <NUM> implanted in the superior-to-inferior trajectory (<FIG>) and lead(s) implanted in the lateral-to-medial trajectory (<FIG>). Lead(s) <NUM> can be implanted in one or both hemispheres of the brain to stimulate one or both NBMs <NUM>. The arrangement of lead(s) <NUM> for each hemisphere can be the same or different.

In at least some embodiments, the area of illumination by one or more light delivery elements <NUM> can be considered analogous to a stimulation region <NUM> for electrical stimulation. All of the features, additional parameters, and other options and considerations described above for electrical stimulation can be applied to optical stimulation. In at least some embodiments, the optical stimulation can be delivered in one or more stimulation periods per day for a duration of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more minutes (or any other suitable duration) per stimulation period.

Any suitable wavelength, wavelength range, or combination of wavelengths can be emitted by the light delivery elements <NUM>. In at least some embodiments, a lead <NUM> can include light delivery elements <NUM> that emit different wavelengths of light or are capable of delivering multiple wavelengths of light. In at least some embodiments, at least one of the light delivery elements <NUM> of a lead <NUM> is capable of emitting light having at least one wavelength in a range of <NUM> to <NUM> or in a range of <NUM> to <NUM>.

In at least some embodiments, a system is configured to deliver both optical and electrical stimulation using the same or different leads. For example, any combination of leads <NUM> and lead <NUM> can be used and any combination of lead trajectories.

In at least some embodiments, an electro-optical stimulation lead can include both electrode(s) <NUM> and light delivery element(s) <NUM>. Examples of such leads are described in the references cited above. In at least some embodiments, the electrode(s) <NUM> and light deliver element(s) <NUM> are both powered by a common implantable power source (for example, power source <NUM> of <FIG>). In other embodiments, the electrode(s) and light deliver element(s) are delivered using different leads coupled to different implantable power sources. The implantable power source(s) can be rechargeable or non-rechargeable.

In at least some embodiments, the electrical, optical, or combined stimulation system is powered transcutaneously via radiofrequency energy or some other external energy source (e.g., ultrasound).

<FIG> is a flowchart of one embodiment of a method of stimulating the NBM. The objective of stimulation of the NBM can be to increase production or delivery of Ach, to reduce slow or halt degeneration of the neurons of the NBM, or the like or any combination thereof. In step <NUM>, one or more electrical stimulation lead, optical stimulation leads, electro-optical stimulation leads, or any combination thereof is implanted in or near the NBM. For example, an electrical stimulation lead or electro-optical stimulation lead may be implanted into the brain of the patient so that at least one or more of the electrodes are disposed in or near the NBM. As another example, an optical stimulation lead or electro-optical stimulation lead may be implanted into the brain of the patient so that at least one or more of the light delivery elements are disposed in or near the NBM. Following implantation, a programming process may be used to determine a set of stimulation parameters for the treatment as discussed above. The IPG may also be implanted. In at least some embodiments, the IPG is implanted in the torso with the lead, or a lead extension coupled to the lead, extending under the skin to the IPG. In at least some embodiments, the lead can be coupled instead to an ETS or other external stimulator.

In step <NUM>, electrical/optical stimulation is delivered through the lead to stimulate the NBM using the set of stimulation parameters. Methods, considerations, and examples of electrical/optical stimulation are described above.

One aspect is a method for stimulating the nucleus basalis of Meynert (NBM) that includes implanting an electrical stimulation lead in a lateral-to-medial trajectory into a brain of a patient, wherein the electrical stimulation lead includes electrodes and at least one of the electrodes is disposed adjacent to or within the NBM of the patient; and delivering electrical stimulation to the NBM through at least one of the electrodes.

In at least some aspects, the method further includes delivering optical stimulation to the NBM using at least one light delivery element of the electrical stimulation lead. In at least some aspects, the method further includes implanting an optical stimulation lead into the brain of the patient, wherein the optical stimulation lead includes at least one light delivery element disposed adjacent to or within the NBM of the patient and delivering optical stimulation to the NBM through at least one of the at least one light delivery elements.

Another aspect is a method for stimulating the nucleus basalis of Meynert (NBM) that includes implanting a plurality of electrical stimulation leads into a brain of a patient, wherein each of the electrical stimulation leads includes a plurality of electrodes and at least one of the electrodes of each of the electrical stimulation leads is disposed adjacent to or within the NBM of the patient; and, for each of a plurality of different stimulation regions of the NBM, delivering electrical stimulation through at least one of the electrodes, wherein the delivery of electrical stimulation to at least some of the stimulation regions is interleaved or sequential.

In at least some aspects, the implanting includes implanting at least one of the electrical stimulation leads in a superior-to-inferior trajectory. In at least some aspects, the implanting includes implanting at least one of the electrical stimulation leads in a lateral-to-medial trajectory.

Yet another aspect is a method for stimulating the nucleus basalis of Meynert (NBM) that includes implanting either a) at least one electro-optical stimulation lead into a brain of a patient or b) at least one electrical stimulation lead and at least one optical stimulation lead into the brain of the patient, wherein each electrical stimulation lead or electro-optical stimulation lead includes at least one electrode with at least one of the at least one electrode disposed adjacent to or within the NBM of the patient and each optical stimulation lead or electro-optical stimulation lead includes at least one light delivery element with at least one of the at least one light delivery element disposed adjacent to or within the NBM of the patient; delivering electrical stimulation to the NBM through at least one of the electrodes; and delivering optical stimulation to the NBM through at least one of the at least one light delivery element.

In at least some aspects, the implanting includes implanting at least one of the at least one electro-optical stimulation lead or the at least one optical stimulation lead in a superior-to-inferior trajectory. In at least some aspects, the implanting includes implanting at least one of the at least one electro-optical stimulation lead or the at least one optical stimulation lead in a lateral-to-medial trajectory.

In at least some aspects, delivering electrical or optical stimulation includes delivering the electrical or optical stimulation to the NBM to stimulate neurons of the NBM to deliver more acetylcholine or to support survival of neurons of the NBM so that they can perform the neuron's function, including delivery of acetylcholine to the cortex. In at least some aspects, the electrodes of the electrical or electro-optical stimulation lead include at least one set of segmented electrodes disposed around a circumference of the electrical or electro-optical stimulation lead.

In at least some aspects, delivering electrical stimulation includes delivering electrical stimulation to a plurality of stimulation regions of the NBM at different periods of time. In at least some aspects, the method further includes selecting the plurality of stimulation regions so that each stimulation region covers a portion of the NBM. In at least some aspects, the selecting includes selecting the plurality of stimulation regions using scoring criteria that promote covering more of the NBM and penalize overlap of the stimulation regions. In at least some aspects, the method further includes determining each of the stimulation regions algorithmically as an estimated volume of effective region of stimulation for a particular set of stimulation parameters.

In at least some aspects, delivering electrical stimulation includes delivering anodic stimulation to the NBM.

In at least some aspects, delivering electrical or optical stimulation includes delivering electrical or optical stimulation when the patient is estimated to be asleep. In at least some aspects, delivering electrical or optical stimulation when the patient is estimated to be asleep includes estimating that the patient is asleep based on a clock in an implantable pulse generator coupled to electrical or optical stimulation lead or in an external device in communication with the electrical or optical stimulation lead or the implantable pulse generator. In at least some aspects, delivering electrical or optical stimulation when the patient is estimated to be asleep includes estimating that the patient is asleep based on a measurement or indication from an external sensor or external device that is in communication with an implantable pulse generator coupled to electrical or optical stimulation lead.

In at least some aspects, delivering electrical stimulation includes delivering electrical or optical stimulation when the patient or another directs the delivery.

It will be understood that each block of the flowchart illustration, and combinations of blocks in the flowchart illustration and methods disclosed herein, can be implemented by computer program instructions. In addition, the feature extraction engine, storage engine, visualization engine, and storage programming engine may be implemented by computer program instructions. These program instructions may be provided to a processor to produce a machine or engine, such that the instructions, which execute on the processor, create means for implementing the actions specified in the flowchart block or blocks or engine disclosed herein. The computer program instructions may be executed by a processor to cause a series of operational steps to be performed by the processor to produce a computer implemented process. The computer program instructions may also cause at least some of the operational steps to be performed in parallel. Moreover, some of the steps may also be performed across more than one processor, such as might arise in a multi-processor computing device. In addition, one or more processes may also be performed concurrently with other processes, or even in a different sequence than illustrated without departing from the scope or spirit of the invention.

The computer program instructions can be stored on any suitable computer-readable medium including, but not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks ("DVD") or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computing device. The computer program instructions can be stored locally or nonlocally (for example, in the Cloud).

Claim 1:
A system for stimulation of a nucleus basalis of Meynert, NBM, of a patient, the system comprising:
an implantable electrical stimulation lead (<NUM>) comprising a plurality of electrodes (<NUM>, <NUM>, <NUM>) and configured for implantation of at least one of the electrodes adjacent to or within the NBM of the patient; and
an implantable pulse generator (<NUM>) coupleable to the implantable electrical stimulation lead and configured for delivering electrical stimulation to the NBM through at least one of the electrodes of the implantable electrical stimulation lead, the implantable pulse generator comprising at least one processor (<NUM>) configured to, upon user request, initially deliver a relatively low level of stimulation and to increase the level of stimulation during an initial period, which is at least <NUM> month in duration and has a start and an end, wherein the increase of the level of stimulation comprises an increase over time of at least one of a duration of a stimulation period or an amplitude of the electrical stimulation from an initial value at the start of the initial period to a final value at the end of the initial period.