US20110172733A1 - Apparatus, system and method for therapeutic treatment of obstructive sleep apnea - Google Patents

Abstract

Provided is an implantable RFID-enabled micro-electronic neurostimulator system for treating obstructive sleep apnea, comprising an implant having a top and a bottom layer, the bottom layer serving as an attachment mechanism such that the bottom layer of the implant encompasses the hypoglossal nerve and attaches to the top layer of the implant; a printed circuit board (PCB) attached to the top layer of the implant, the PCB having a first and a second opposing sides; a neural interface attached to the second side of the PCB; a core subsystem (CSS) attached to the first side of the PCB and electrically connected to the neural interface; and a radio frequency (RF) interface attached to the first side of the PCB and electrically connected to the CSS, wherein the implant is powered and controlled by an external programmable controller.

Description

RELATED APPLICATIONS
• This application claims priority to U.S. Provisional Applications 60/774,039, 60/774,040, and 60/774,041 filed on Feb. 16, 2006, which are expressly incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
• The present invention relates to an apparatus, system, and method for implantable therapeutic treatment of obstructive sleep apnea.
BACKGROUND OF THE INVENTION
• Sleep apnea is a physiological condition affecting millions of people worldwide. It is described as an iterated failure to respire properly during sleep. Those affected by sleep apnea stop breathing during sleep numerous times during the night. There are two types of sleep apnea, generally described in medical literature as central sleep apnea and obstructive sleep apnea. Central sleep apnea is a failure of the nervous system to produce proper signals for excitation of the muscles involved with respiration. Obstructive sleep apnea (OSA) is cause by physical obstruction of the upper airway channel (UAW).
• Obstruction of the upper airway is associated with a depression of the respiratory system caused by a loss of tone of the oropharyngeal muscles involved in maintaining UAW patency. As those muscles lose tone, the tongue and soft tissue of the upper airway collapse, blocking the upper airway channel. Blockage of the upper airway prevents air from flowing into the lungs. This creates a decrease in blood oxygen level, which in turn increases blood pressure and heart dilation. This causes a reflexive forced opening of the UAW until the patient regains normal patency, followed by normal respiration until the next apneic event. These reflexes briefly arouse the patient from sleep (microarousals).
• Current treatment options range from non-invasive approaches such as continuous positive applied pressure (CPAP) to more invasive surgical procedures such as uvulopalatopharyngoplasty (UPPP) and tracheostomy. In both cases patient acceptance and therapy compliance is well below desired levels, rendering the current solutions ineffective as a long term solution-for therapeutic treatment of OSA.
• Implants are a promising alternative to these forms of treatment. Pharyngeal dilation via hypoglossal nerve (XII) stimulation has been shown to be an effective treatment method for OSA. The nerves are stimulated using an implanted electrode. In particular, the medial XII nerve branch (i.e., in. genioglossus), has demonstrated significant reductions in UAW airflow resistance (i.e., increased pharyngeal caliber).
• Reduced UAW airflow resistance, however, does not address the issue of UAW compliance (i.e., decreased UAW stiffness), another critical factor involved with maintaining patency. To this end, co-activation of both the lateral XII nerve branches (which innervate the hyoglossus (HG) and styloglossus (SG) muscles) and the medial nerve branch has shown that the added effects of the HG (tongue retraction and depression) and the SG (retraction and elevation of lateral aspect of tongue) result in an increased maximum rate of airflow and mechanical stability of the UAW.
• While coarse (non-selective) stimulation has shown improvement to the AHI (Apnea+Hypopnea Index) the therapeutic effects of coarse stimulation are inconclusive. Selective stimulation of the functional branches is more effective, since each branch-controlled muscle affects different functions and locations of the upper airway. For example, activation of the GH muscle moves the hyoid bone in the anterosuperior direction (towards the tip of the chin). This causes dilation of the pharynx, but at a point along the upper airway that is more caudal (below) to the base of the tongue. In contrast, activation of the HG dilates the oropharynx (the most commonly identified point of collapse, where the tongue and soft palate meet) by causing tongue protrusion. Finally, the tongue retractor muscles (HG and SG) do not themselves generate therapeutic effects, but they have been shown to improve upper airway stability when co-activated with the HG muscle.
• While electrical stimulation of the hypoglossal nerve (HGN) has been experimentally shown to remove obstructions in the UAW, current implementation methods require accurate detection of an obstruction, selective stimulation of the correct tongue muscles, and a coupling of the detection and stimulation components. Additionally, attempts at selective stimulation have to date required multiple implants with multiple power sources, and the scope of therapeutic efficacy has been limited. A need therefore exists for an apparatus and method for programmable and/or selective neural stimulation of multiple implants or contact excitation combinations using a single controller power source.
SUMMARY OF THE INVENTION
• The present invention relates to an apparatus, system; and method for selective and programmable implants for the therapeutic treatment of obstructive sleep apnea.
• In one embodiment, an implantable RFID-enabled micro-electronic neurostimulator system for treating obstructive sleep apnea includes an external subsystem and an internal subsystem. In this embodiment, the internal subsystem includes an implant having a top and a bottom layer, the bottom layer serving as an attachment mechanism such that the bottom layer of the implant encompasses the HGN and attaches to the top layer of the implant. A printed circuit board (PCB) is attached to the top layer of the implant, with the PCB having first and second opposing sides. A neural interface attaches to the second side of the PCB. A core subsystem (CSS) attaches to the first side of the PCB and electrically connects to the neural interface. An internal radio frequency (RF) interface attaches to the first side of the PCB and is electrically connected to the CSS. The power may be supplied by RF energy emitted from the external subsystem.
• In some embodiments, the external subsystem includes a controller. The controller may include a port for interfacing with a computer. A computer may interface with the controller through the port to program patient-specific nerve physiology and stimulation parameters into the controller. The controller may be shaped for placement around a patient's ear. The controller may identify an implant having a unique ID tag, communicate with an implant having the unique ID tag, and send a signal to a transponder located in the implant. In some embodiments, the transponder is a passive RFID transponder. In other embodiments, the transponder is an active transponder. In still further embodiments, the controller provides an RF signal to the implant, senses and records data, and interfaces with a programming device. The controller may also communicate with the implant at preprogrammed intervals. In other embodiments, the controller initiates a stimulation cycle by making a request to the CSS, the request being in the form of an encoded RF waveform including control data. The request may be encrypted.
• In some embodiments, the implant provides continuous open loop electrical stimulation to the HGN. In other embodiments, the implant provides closed loop stimulation. The stimulation may be constant, or it may be at preprogrammed conditions. Stimulation may be applied during sleep hours, or it may be applied while the patient is awake. The stimulation may be bi-phasic stimulation of the HGN, with a stimulation pulse width of about 200 microseconds and a stimulation frequency of about 10-40 Hertz. The implant may be hermetically sealed. In other embodiments, the implant delivers multiple modes of stimulation. The stimulation can be in multiple dimensions.
• Stimulation may be provided by a neural interface. This stimulation may be applied to the HGN. In certain embodiments, the neural interface includes a plurality of individual electrodes. In further embodiments, the neural interface electrodes include an array of anodes and cathodes, which in some embodiments are a plurality of exposed electrode pairs serving as anode and cathode complementary elements. In certain other embodiments, the electrodes are spot welded to the PCB and include material selected from the group consisting of platinum and iridium. In certain embodiments, the neural interface includes no external wires or leads. In still further embodiments, the neural interface includes a matrix of platinum electrodes coupled to the fascicles of the hypoglossal nerve (HGN). In some embodiments, the neural interface senses neural activity of the nerve it interfaces with, and transmits that sensed neural activity to the core subsystem.
• In some embodiments, the core subsystem (CSS) of the implant is included in a silicon chip placed on the top of the printed circuit board PCB, with the chip connected to the neural interface via traced wires printed on the PCB. The chip may be powered by and receive a customized electrode stimulation program protocol from the controller. Upon receiving a request to enter into a stimulation state the CSS selects a trained waveform from memory and starts stimulation by providing an electrical signal to the neural interface. In some embodiments, the core subsystem reports completion of a stimulation state to the controller via an RF communication and optionally goes to an idle state.
• Methods for treating obstructive sleep apnea are also disclosed. In one method, a hypoglossal nerve (HGN) is selectively stimulated. A neural interface is implanted in a fascicle of the HGN. The neural interface senses and records neural activity, and feeds the sensed neural activity information into a parameterized control algorithm. In certain embodiments, an external subsystem inductively coupled to an RFID senses and records the neural activity. The algorithm compares the sensed information to a reference data set in real time, transmits in real time an output of the parameterized control algorithm from an external RF interface to an internal RF interface, and from the internal RF interface to a microprocessor. Stimulus information may be calculated and communicated between the external RF interface and the internal RF interface in real time. In another method, bi-phasic electrical stimulation is applied to individual fascicles of the hypoglossal nerve using selectively excitable individual electrodes arranged in a planar field.
BRIEF DESCRIPTION OF THE DRAWINGS
• The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. In the drawings:
• FIG. 1 shows an embodiment of an internal subsystem.
• FIG. 2 shows an embodiment of an internal subsystem with the core subsystem and internal RF interface in a silicon package.
• FIG. 3 shows a hypoglossal nerve an implant.
• FIG. 4 shows multiple embodiments of neural interface electrode arrays.
• FIG. 5 shows an embodiment of an internal subsystem implant.
• FIG. 5A is a breakout view ofFIG. 1.
• FIG. 6A shows an embodiment of an internal subsystem with the neural interface electrodes on the bottom layer of the implant.
• FIG. 6B shows an embodiment of an internal subsystem with the neural interface electrodes on the top and bottom layers of the implant.
• FIG. 7 shows an embodiment of an external subsystem with a controller.
• FIG. 8 shows two embodiments of the external controller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
• One embodiment the present invention includes an external subsystem and an internal subsystem. In certain embodiments, the external subsystem includes one or more of (1) a controller, (2) an external RF interface, and (3) an optional power source. The internal subsystem may include an implant. In certain embodiments, the implant includes one or more of (1) a neural interface which can include an array of electrodes where at least one electrode contacts a nerve, (2) a core subsystem, and (3) an internal RF interface. In some embodiments, the neural interface may further include a digital to analog signal converter and a multiplexer.
• In some embodiments the core subsystem may include a microprocessor. The microprocessor may have a micrologic CPU and memory to store protocols selective to a patient. The microprocessor may be part of an integrated silicon package. In still further embodiments, the internal RF interface may include one or more of a transponder, internal antenna, modulator, demodulator, clock, and rectifier. The transponder can be passive or active. In some embodiments, one or more of a controller, external RF interface, and optional power source are positioned on the skin of a user/patient, typically directly over or in close proximity to, an implant.
• In certain embodiments, the external subsystem controller can be in the form of an earpiece or patch including any one or more of the controller, external RF interface, and optional power source, e.g., a battery, AC to DC converter, or other power sources known to those skilled in the art. In certain embodiments, the external subsystem can send and receive control logic and power using an external RF interface. In such embodiments, the external subsystem can further include one or more of a crypto block, data storage, memory, recording unit, microprocessor, and data port. In some embodiments the microprocessor may have a micrologic CPU and memory to store protocols selective to a patient. The microprocessor may be part of an integrated silicon package.
• Each of the components of various embodiments of the claimed invention is described hereafter. In certain embodiments, the present invention is an open loop system. In other embodiments the present invention is a closed loop system. The components of the embodiments can be rearranged or combined with other embodiments without departing from the scope of the present invention.
• The Internal Subsystem
• In certain embodiments, the internal subsystem includes an implant, which includes one or more of (1) a core subsystem, (2) a neural interface, and (3) an internal RF interface. Certain embodiments of the implant components and component arrangements are described below.
• Implant Components
• The following paragraphs describe embodiments of the implant of the present invention, which includes one or more of a core subsystem, neural interface, and internal RF interface components.
• The Core Subsystem
• FIG. 1 shows an embodiment of theinternal subsystem100. In certain embodiments theinternal subsystem100 includes an implant105 (non-limiting representative embodiments ofimplant105 are shown inFIGS. 3,5,5A,6A,6B, and8) which may have acore subsystem140. The middle portion ofFIG. 1 shows a detailed view of an embodiment of thecore subsystem140. Thecore subsystem140 may include one or more of a power module144,microprocessor141,crypto block142, andinput output buffer143. In certain embodiments, themicroprocessor141 may have a micrologic CPU, and may have memory to store protocols selective to a patient. In the embodiment shown, the core subsystem includes a power module144, acore subsystem microprocessor141 for managing communication with anexternal RF interface203, at least one I/O buffer143 for storing inbound and outbound signal data, and a coresubsystem crypto block142. In some embodiments, thecore subsystem microprocessor141 communicates with theexternal RF interface203 in full duplex. Thecore subsystem microprocessor141 may generate signals for controlling stimulation delivered by theneural interface160, and it may processes signals received from theneural interface160. In certain embodiments, the core subsystem microprocessor logic includes an anti-collision protocol for managing in-range multiple transponders and readers, a management protocol for reset, initialization, and tuning of theimplant105, and a protocol to facilitate the exchange of data with theneural interface160. Thecore subsystem microprocessor141 is programmable and may further include an attached non-volatile memory. Themicroprocessor141 may be a single chip145 or part of anintegrated silicon package170.
• FIG. 2 shows an embodiment of aninternal subsystem100 with thecore subsystem140 andinternal RF interface150 in asilicon package170. For size comparison,FIG. 2 shows thecore subsystem140,internal RF interface150, andcore subsystem microprocessor141 next to thesilicon package170.
• The Neural Interface
• The right portion ofFIG. 1 shows an embodiment of aneural interface160. Theneural interface160 can include an array ofelectrodes161 where at least oneelectrode161 contacts a nerve. In one embodiment, theneural interface160 includes an array of 10 to 16electrodes161. This arrangement is exemplary only however, and not limited to the quantity or arrangement shown. Thecore subsystem140 connects to theneural interface160, and controls neural interface stimulation. In the embodiment shown, theneural interface160 is attached to the printedcircuit board130. In some embodiments, theneural interface160 may further include a digital toanalog signal converter164 and a multiplexer166. In certain embodiments the multiplexer166 is included on the printedcircuit board130. In other embodiments, the multiplexer166 is included on a thin layer film or flexible membrane around the surface of the chip.
• In the embodiment shown, theneural interface160 receives power from RF waves received by theimplant105. In one embodiment, the D/A converter164 uses the RF waves to power one or more capacitors165, which may be located in theconverter164. In certain embodiments, the capacitors165 are arranged in an array on a microfilm. These capacitors165 store charges, which are used to generate analog burst pulses for delivery by theneural interface160. In embodiments including a multiplexer166, the multiplexer166 may be used to deliver power to multiple capacitors165, and can be used to deliver power tomultiple electrodes161 in theneural interface160. In still further embodiments, the multiplexer166 is programmable.
• In certain embodiments, theneural interface160 is physically located on the opposite side of the printedcircuit board130 to which thecore subsystem140 is attached. In other embodiments, the one ormore electrodes161 are physically separated from thecore subsystem140 by the printedcircuit board130. Eachelectrode161 connects to thecore subsystem140 through wires133 (e.g., traced wires) on the printedcircuit board130. This layered approach to separating thecore subsystem140 from theelectrodes161 has significant benefits in the bio-compatible coating and manufacturing of the implant. By minimizing the area exposed to the HGN, the bio-compatible coating is only required in the area surrounding the exposed parts of theelectrodes161.
• Theelectrodes161 may be manufactured with biocompatible material coating. In certain embodiments, the electrodes may include embedded platinum contacts spot-welded to a printedcircuit board130 on theimplant105. Theelectrodes161 may be arrayed in a matrix, with the bottoms of theelectrodes161 exposed for contact to the HGN. Since theelectrodes161 attach to the top portion of thecore subsystem140 through leads on the printed circuit board, there is no need for wire-based leads attached to the contact points, allowing for miniaturization of theelectrodes161.
• FIG. 3 shows a hypoglossal nerve implanted with aneural interface160. In one embodiment, exposed portions of theneural interface160 deliver selective stimulation to fascicles of the HGN. Selective stimulation allows co-activation of both the lateral HGN branches, which innervate the hypoglossus (HG) and styloglossus (SG), and the medial branch. This selective stimulation of HG (tongue retraction and depression) and the SG (retraction and elevation of lateral aspect of tongue) results in an increased maximum rate of airflow and mechanical stability of the upper airway (UAW). Selective stimulation is a unique approach to nerve stimulation when implanted on the hypoglossal nerve (HGN). Theneural interface160 may also sense the neural activity of the nerve it interfaces with and may transmit that sensed activity to thecore subsystem microprocessor141.
• FIG. 4 shows embodiments of neural interface electrode arrays. These embodiments are exemplary only, and the arrays are not limited to the quantity or arrangement of the electrodes shown in the figure. In one embodiment, at least oneelectrode161 is in contact with a nerve. In certain embodiments, theelectrodes161 may be in the shape of a linear, regular, or irregular array. In certain embodiments, theelectrode161 array may be in a form suitable for wrapping around a nerve (e.g., a helical shape or spring-like shape as shown inFIG. 3). Theelectrodes161 may also be arranged in a planar form to help reshape the nerve and move the axons closer to theelectrodes161. This facilitates access to multiple nerve axons, which enables multiple modes of stimulation for enhanced UAW dilation and stability. With a planar form factor, stimulation can also be delivered in two dimensions, enabling optimal excitation of the functional branches of the nerve. Excitation happens through bi-phasic electrical stimulation ofindividual electrodes161.
• The Internal RF Interface
• The left portion ofFIG. 1 shows a detailed view of an embodiment of theinternal RF interface150. Theinternal RF interface150 may include one or more of atransponder156,internal antenna151,modulator157,demodulator158, clock159, and rectifier. Thetransponder156 can be passive or active. In certain embodiments, theinternal RF interface150 can send and/or receive one or more of (1) control logic, and (2) power. In still further embodiments, theinternal RF interface150 delivers one or more of power, clock, and data to theimplant core subsystem140. In certain embodiments the data is delivered via a full duplex data connection. In some embodiments, theinternal RF interface150 sends data (e.g., function status) of one ormore electrodes161 to acontroller205, described below, for review by a technician or physician.
• Theinternal RF interface150 operates according to the principle of inductive coupling. In an embodiment, the present invention exploits the near-field characteristics of short wave carrier frequencies of approximately 13.56 MHz. This carrier frequency is further divided into at least one sub-carrier frequency. In certain embodiments, the present invention can use between 10 and 15 MHz. Theinternal RF interface150 uses a sub carrier for communication with anexternal RF interface203, which may be located in thecontroller205. The sub-carrier frequency is obtained by the binary division of theexternal RF interface203 carrier frequency. In the embodiment shown, theinternal RF interface150 is realized as part of asingle silicon package170. Thepackage170 may further include a chip145 which is a programmable receive/transmit RF chip.
• In certain embodiments, theinternal RF interface150 also includes apassive RFID transponder156 with ademodulator158 and amodulator157. Thetransponder156 uses the sub carrier to modulate a signal back to theexternal RF interface203. In certain embodiments, thetransponder156 may further have two channels, Channel A and Channel B. Channel A is for power delivery and Channel B is for data and control. Thetransponder156 may employ a secure full-duplex data protocol.
• Theinternal RF interface150 further includes an inductive coupler152, an RF to DC converter155, and aninternal antenna151. In certain embodiments, theinternal antenna151 includes a magnetic component. In such embodiments, silicon traces may be used as magnetic antennas. In other embodiments, the antenna may be a high Q coil electroplated onto a silicon substrate. A parallelresonant circuit153 may be attached to theinternal antenna151 to improve the efficiency of the inductive coupling. Theinternal antenna151 may be realized as a set of PCB traces133 on theimplant105. Size of the antenna traces is chosen on the basis of power requirements, operating frequency, and distance to thecontroller205. Both theinternal RF interface150 and thecore subsystem microprocessor141 are powered from an RF signal received by theinternal antenna151. A shunt regulator154 in theresonant circuit153 keeps the derived voltage at a proper level.
• Implant Component Arrangement
• Theimplant105 may be located on any suitable substrate and may be a single layer or multi-layer form.FIG. 5 shows animplant105 constructed as a single integrated unit, with atop layer110 and abottom layer110 which may be implanted in proximity to, in contact with, or circumferentially around a nerve, e.g., the hypoglossal nerve.FIG. 5A is a breakout view ofFIG. 5.
• In certain embodiments, implant components are layered on a nerve. This alleviates the need for complex wiring and leads. InFIGS. 5 and 5A, thetop layer110 includes acore subsystem140, aninternal RF interface150, and aneural interface160. Thetop layer110 serves as the attachment mechanism, with the implant components on thebottom layer110. Theneural interface160 may be surface bonded to contacts on a printedcircuit board130. Thebottom layer110 is complementary to thetop layer110, and serves as an attachment mechanism so that theimplant105 encompasses the HGN. Although conductive parts in contact with the HGN may be located at any suitable position on theimplant105, in the embodiment shown inFIGS. 5 and 5A, thebottom layer110 has no conductive parts.
• In the embodiment shown inFIGS. 5 and 5A, and as described above, thecore subsystem140 is included in a silicon package170 (FIG. 2) attached to a printed circuit board (PCB)130 on thetop layer110. ThePCB130 has afirst side131 and asecond side132. Thesilicon package170 is placed on afirst side131 of the printedcircuit board130. In certain embodiments thePCB130 may be replaced with a flexible membrane substrate. In the embodiment shown, thesilicon package170 further includes theinternal RF interface150. Theneural interface160 attaches to thesecond side132 of thePCB130. In this embodiment, the neural interface160 (FIG. 6B) further includes a plurality of neural interface electrodes161 (FIG. 4) arranged into anode and cathode pairs162/163, shown in this embodiment as an array of 10 to 16 elements. The number and arrangement of anode and cathode pairs162/163 is exemplary only, and not limited to the embodiment shown. The silicon package170 (FIG. 2) connects to the anode and cathode pairs162/163 via tracedwires133 printed on thePCB130.
• In other embodiments, such as the one shown inFIG. 6A, the neural interface electrode anode and cathode pairs162/163 are located on thebottom layer110 of theimplant105. In still other embodiments, such as the one shown inFIG. 6B, the neural interface electrode anode and cathode pairs162/163 are located on both the top and thebottom layers110/120. The matrix arrangement ofelectrodes161 provides multiple nerve stimulating points, and has several advantages. The matrix arrangement allows a web of nerve fascicles of the hypoglossal nerve to be accessed, enabling selective stimulation of particular areas of the nerve. In some embodiments, power is delivered to the matrix ofelectrodes161 from the D/A converter164 to capacitors165 via a multiplexer166.
• Theimplant105 may further include an isolation layer112 (FIG. 6A). In certain embodiments a protective coating114 (FIGS. 6A and 6B) may be applied to the top andbottom layers110/120 of theimplant105. Theimplant105 may further be coated with aprotective coating114 for biological implantation. Further, in certain embodiments all or a portion of the device may be encased in a biocompatible casing. In such embodiments, the casing may be a material selected from the group consisting of one or more titanium alloys, ceramic, and polyetheretherketone (PEEK).
• The External Subsystem
• In certain embodiments, theexternal subsystem200 may include one or more of (1) a controller, (2) an external RF interface and (3) an optional power source. An embodiment of anexternal subsystem200 including these elements is shown inFIG. 7. Typically theexternal subsystem200 is located externally on or near the skin of a patient.
• The Controller
• FIG. 7 shows an embodiment of anexternal subsystem200 with acontroller205. Thecontroller205 controls and initiates implant functions. In other embodiments, thecontroller205 may be part of theinternal subsystem100 instead ofexternal subsystem200, and in still further embodiments, portions of thecontroller205 may be in both the external andinternal subsystems200/100. In certain embodiments, thecontroller205 may further have one or more of acontroller crypto block201,data storage206, arecording unit207, and acontroller microprocessor204. In some embodiments thecontroller microprocessor204 may have a micrologic CPU and memory to store protocols selective to a patient. Thecontroller microprocessor204 is programmable and may further include an attached non-volatile memory. Themicroprocessor204 may be a single chip or part of an integrated silicon package.
• In certain embodiments, the controller may further include includes one or more of an external RF interface having RF transmit and receive logic, a data storage that may be used to store patient protocols, an interface (e.g., a USB port), a microprocessor, an external antenna, a functionality to permit the controller to interface with a particular implant, and an optional power source. In certain embodiments, the controller electronics can be either physically or electromagnetically coupled to an antenna. The distance between the external RF interface antenna (not shown) and theimplant105 may vary with indication. In certain embodiments, distance is minimized to reduce the possibility of interference from other RF waves or frequencies. Minimizing the distance between the external antenna and theimplant105 provides a better RF coupling between the external andinternal subsystems200/100, further reducing the possibility of implant activation by a foreign RF source. An encrypted link between the external andinternal subsystems200/100 further reduces the possibility of implant activation by foreign RF. In other embodiments, one or more of theinternal antenna151 and external antennas209 are maintained in a fixed position. Potential design complexity associated with internalRF interface antenna151 orientation is minimized through the ability to position the external RF interface antenna in a specific location (e.g., near the patient's ear). Even if the patient moves, the internalRF interface antenna151 andcontroller205 remain coupled.
• In certain other embodiments, thecontroller205 can also serve as (1) a data gathering and/or (2) programming interface to theimplant105. Thecontroller205 has full control over the operation of theimplant105. It can turn theimplant105 on/off, and may be paired to theimplant105 via a device specific ID, as described herein below with respect to use of theimplant105 andcontroller205 of the present invention. In still further embodiments, thecontroller microprocessor204 calculates stimulus information. The stimulus information is then communicated to theimplant105. Theimplant105 then provides a calculated stimulus to a nerve. In another embodiment, thecontroller205 preloads theimplant105 with an algorithmic protocol for neural stimulation and then provides power to theimplant105.
• External RF Interface
• In the embodiment shown inFIG. 7, theexternal subsystem200 includes anexternal RF interface203 that provides an RF signal for powering and controlling theimplant105. Theexternal RF interface203 can be realized as a single chip, a plurality of chips, a printed circuit board, or even a plurality of printed circuit boards. In other embodiments, the printed circuit board can be replaced with a flexible membrane. Theexternal RF interface203 may include one or more of a transponder208 (not shown), external antenna (not shown), modulator210 (not shown), and demodulator211 (not shown), clock212 (not shown), and rectifier213 (not shown) (not shown). The external RF interface transponder208 can be passive or active. In certain embodiments, theexternal RF interface203 can send and/or receive one or more of (1) control logic, and (2) power. In still further embodiments, theexternal RF interface203 delivers one or more of power, clock, and data to one or more of theexternal subsystem controller205 and theinternal subsystem100 via theinternal RF interface150. In certain embodiments the data is delivered via a full duplex data connection. In an embodiment, theexternal RF interface203 operates at a carrier frequency of approximately 13.56 MHz. In certain embodiments, theexternal RF interface203 can operate between 10 and 15 MHz. This carrier frequency is further divided into at least one sub-carrier frequency. The sub-carrier frequency is obtained by binary division of theexternal RF interface203 carrier frequency. Theexternal RF interface203 uses the sub carrier for communication with theinternal RF interface150. The external RF interface transponder208 (not shown) uses the sub carrier to modulate a signal to theinternal RF interface150. The transponder208 (not shown) may further have two channels, Channel A and Channel B. Channel A is for power delivery and Channel B is for data and control. The transponder208 (not shown) may employ a secure full-duplex data protocol.
• In certain embodiments, theexternal RF interface203 may further include a demodulator211 (not shown) and a modulator210 (not shown). In still further embodiments, theexternal RF interface203 further includes an external antenna. In certain embodiments, the external antenna includes a magnetic component. In such embodiments, silicon traces may be used as magnetic antennas. The antenna may be realized as a set of PCB traces. Size of the antenna traces is chosen on the basis of power requirements, operating frequency, and distance to theinternal subsystem100. In certain embodiments, the external antenna may transmit the power received byinternal subsystem100. In certain other embodiments, the external antenna may be larger, and have a higher power handling capacity than theinternal antenna151, and can be realized using other antenna embodiments known by those skilled in the art.
• In certain embodiments, theexternal subsystem200 is loosely coupled to anoptional power source215. In one embodiment, thecontroller power source215 is not co-located with the external RF interface antenna. Theexternal power source215 may be in one location, and theexternal RF interface203 and optionally thecontroller205 are in a second location and/or third location. For example, each of thepower source215,controller205 andexternal RF interface203 can be located in difference areas. In one embodiment, thepower source215 and thecontroller205 and theexternal RF interface203 are each connected by one or more conductive members, e.g. a flexible cable or wire. Additionally, in certain embodiments, thecontroller205 andoptional power source215 may be co-located, and theexternal RF interface203 may be located elsewhere (i.e., loosely coupled to the controller205). In such embodiments, theexternal RF interface203 is connected to thecontroller205 by a flexible cable or wire.
• Since thepower source215 may be separately located from thecontroller205 and/or external RF interface antenna, alarger power source215 can be externally located but positioned away from the nerve that requires stimulation. Further, to reduce wasted power, a larger external RF interface antenna can be used. This provides the advantage of less discomfort to a user and therefore enhances patient compliance.
• Such embodiments can also provide power to 2, 3, 4, 5 or more loosely coupled external RF interfaces203. Thus, eachexternal RF interface203 can be positioned at or near the site of animplant105 without the need for aco-located power source215. In certain embodiments, eachexternal RF interface203 draws power from asingle power source215, and thus asingle power source215 powers a plurality ofimplants105. Of course, the amount of power provided to eachimplant105 will vary by indication and distance between theexternal RF interface203 and theimplant105. The greater the distance between theexternal RF interface203 and theimplant105, the greater the power level required. For example, a lower power is generally required to stimulate peripheral nerves, which are closer to the surface of the skin. As apparent to one of skill in the art, the power received at theimplant105 must be high enough to produce the desired nerve stimulus, but low enough to avoid damaging the nerve or surrounding tissue.
• Theexternal RF interface203 may further include a programmable receive/transmit RF chip, and may interface with thecontroller crypto unit201 for secure and one-to-one communication with its associatedimplant105. Theexternal RF interface203 includes a parameterized control algorithm, wherein the parameterized control algorithm compares the sensed information to a reference data set in real time. The algorithm may be included in thecontroller microprocessor204. Depending upon the patient's size and severity of disease state, the algorithm will vary a number of parameters which include frequency, amplitude of the signal, number of electrodes involved, etc.
• Interaction with Outside Information Sources
• Theexternal subsystem controller205 may also interface with a computer. In some embodiments, thecontroller interface202 is a built-in data port (e.g., a USB port). Via the controller interface202 a computer may tune (and re-tune) the implant system, and transfer historical data recorded by theimplant105. Thecontroller205 may obtain and update its software from the computer, and may upload and download neural interface data to and from the computer. The software may be included in thecontroller microprocessor204 and associated memory. The software allows a user to interface with thecontroller205, and stores the patient's protocol program.
• External Subsystem Design
• Theexternal subsystem200 can be of regular or irregular shape.FIG. 8 shows two embodiments of anexternal subsystem controller205, one with thecontroller205 included with an earpiece much like a Bluetooth earpiece, and one with thecontroller205 included with a patch. In the embodiments shown, potential design complexity associated withinternal RF antenna151 orientation is minimized through the single and fixed position of thecontroller205. The patient may move and turn without disrupting the coupling between thecontroller205 and theinternal antenna151. In the embodiment with thecontroller205 in an earpiece, a flexible receive/transmit tip in the earpiece aligns the controller external RF interface antenna with theimplant105. In the embodiment with thecontroller205 in a patch, the patch is aligned with theimplant105 and placed skin. The patch may include one or more of thecontroller205, a replaceable adhesive layer, power and RFID coupling indication LED, and a thin layer rechargeable battery. Still further embodiments include incorporation of theexternal subsystem200 into a watch-like device for, e.g., the treatment of arthritic pain, or in a belt. Yet another range of variations are flexible antennas and the controller RF chip woven into clothing or an elastic cuff, attached to controller electronics and remotely powered.Controller205 designs may be indication specific, and can vary widely. Thecontroller205 embodiments inFIG. 8 are exemplary only, and not limited to those shown.
• Communication with the Implant as a Function of Design
• The distance between this contact area and theactual implant100 on a nerve is 1 to 10 cm, typically 3 cm, through human flesh. This distance, along with thecontroller crypto unit201 and the coresubsystem crypto unit142 in theimplant100, reduces potential interference from other RF signals.
• Implant and Controller Positioning
• Prior to implantation of the present invention for the treatment of sleep apnea, patients are diagnosed in a sleep lab, and animplant105 is prescribed for their specifically diagnosed condition. Once diagnosis is complete, theimplant105 is surgically implanted in the patient's body, typically on or in the vicinity of a nerve. In certain embodiments, theimplant105 is implanted on the HGN. In such embodiments, theimplant105 may be implanted below the ear unilaterally at the sub-mandibular triangle, encasing the hypoglossal nerve.
• Stimulation of the HGN can act to maintain nerve activity. Hence in certain embodiments, the present invention can maintain muscular tone (e.g., in the tongue, thereby preventing apnea). Therefore, in certain embodiments,controller205, described in more detail above, activatesimplant105 to stimulate HGN activity to ameliorate the negative physiological impact associated with insufficient tone muscles caused by, e.g., insufficient HGN activity.
• Once implanted, theimplant105 is used to stimulate the nerve. In embodiments where the device is implanted in a manner to stimulate the HGN, theimplant105 delivers tone to the tongue. Maintaining tongue muscle tone stops the tongue from falling back and obstructing the upper airway. The stimulation may be provided continuously during sleep hours, or upon preprogrammed patient-specific intervals. Theimplant105 may also sense and record neural activity.
• Implant and Controller Security
• In certain embodiments, thecontroller205 identifies the patient's unique ID tag, communicates with and sends signals to theimplant105. In certain embodiments, acontroller crypto unit201 may be installed to ensure that communication between thecontroller205 and theimplant105 is secure and one-to-one. Thecontroller crypto unit201 may include the implant's unique ID tag.
• In particular, theimplant105 may have a unique ID tag, which thecontroller205 can be programmed to recognize. Acontroller microprocessor204 confirms the identity of theimplant105 associated with thecontroller205, thereby allowing setting of the patient's specific protocol. The setting may be accomplished using a computer interfaced with thecontroller205 through aninterface202 on thecontroller205.
• More particularly, once thecontroller crypto unit201 establishes a link with the coresubsystem crypto unit142, thecontroller205 communicates a stimulation scenario to thecore subsystem microprocessor141. Thecontroller205 initiates a stimulation cycle by making a request to thecore subsystem140 by sending an encoded RF waveform including control data via theexternal RF interface203. Thecore subsystem140 selects a trained waveform from memory and transmits the stimulation waveform to thecore subsystem microprocessor141. Once thecore subsystem microprocessor141 receives the waveform, thecore subsystem140 generates a stimulating signal for distribution to theneural interface160.
• Interaction with the Implant
• In certain embodiments, thecontroller205 prevents self-activation or autonomous operation by theimplant105 by handshaking. Handshaking occurs during each communications cycle and ensures that security is maintained. This prevents other devices operating in the same frequency range from compromising operation of theimplant105. Implant stimulus will not commence unless an encrypted connection is established between theexternal RF interface203 and theimplant105. This serves as an anti-tampering mechanism by providing theimplant105 with a unique ID tag. Theexternal controller205 is matched, either at the point manufacture or by a physician, to a particular ID tag of theimplant105, typically located in an EPROM of theimplant105. In certain embodiments, the EPROM may be included in thecore subsystem microprocessor141. In other embodiments, the EPROM may be included in thecontroller microprocessor204. This prevents alien RF interference from ‘triggering’ activation of theimplant105. While arbitrary RF sources may provide power to theimplant105, the uniquely matchedcontroller205 establishes an encrypted connection before directing theimplant105 to commence stimulus, thereby serving as a security mechanism.
• System Programming
• Desired system programming is determined by measuring a patient's tongue activity against predetermined stimulation protocols. The effectiveness of theneural interface160 stimulation protocols are measured until a desired tongue stimulation level is achieved. Once a desired tongue stimulation level is achieved, those protocols are programmed into thecontroller205. Stimulation may be programmed for delivery in an open loop or closed loop at a suitable frequency. In certain embodiments, a stimulation frequency of about 10-40 Hz is used. Stimulation may also be delivered in pulses, with pulse widths about 100 to 300 microseconds, more typically 200 microseconds. Although any suitable pulse width can be used, preferred pulses are at a width that simultaneously prevent nerve damage and reduce or eliminate corrosion of neural interface electrodes. After thecontroller205 is programmed, the patient activates thecontroller205 at bed time or at desired intervals.
• In certain embodiments,controller205 can also determine when the patient is asleep, and stimulate the HGN based on that determination. In order to determine when the patient is asleep,controller205 can include one or more sensors that generate signals as a function of the activity and/or posture of the patient. In such embodiments,controller205 determines when the patient is asleep based on the signal.Controller205 can also have an acoustic sensor, to indicate when snoring starts, and can determine whether the patient is asleep based on the presence of snoring. In other embodiments the patient may enter an input into thecontroller205 telling it to commence treatment. However, as noted above,controller205 can be activated by a user and then function in a manner such that the implant is continuously active until the patient awakens and manually deactivates the controller by pressing a button on thecontroller205 or by moving thecontroller205 out of range of the implant.
• This electrical stimulation provides a signal to the HGN and starts the treatment of the airway obstruction. Upon completion of one cycle, the duration of which is determined in the tuning phase of the implantation procedure, described above, thecore subsystem140 can report completion back to thecontroller205 via RF communication, and optionally goes to an idle state until receiving another set of instructions.
• As described above, in certain embodiments, theimplant105 is externally powered by near field RF waves, the RF waves are inductively converted to DC power, which powers theimplant105 and delivers electrical signals to selected elements of theneural interface160. The implant uses between 0.1 to about 1 milliamps, preferably averaging about 0.5 milliamps of current and about 10 to 30 microwatts of power.
• In some embodiments, the near field RF waves are emitted from thecontroller205. In certain embodiments,controller205 can be powered by anoptional power source215, e.g., a battery, AC to DC converter, or other power source known to those skilled in the art.
• Other embodiments of the apparatus and methods described can be used in the present invention. Various alternatives, substitutions and modifications for each of the embodiments and methods of the invention may be made without departing from the scope thereof, which is defined by the following claims. All references, patents and patent applications cited in this application are herein incorporated by reference in their entirety.

Claims (20)

1-44. (canceled)

45. An implantable neurostimulator for treating obstructive sleep apnea in a patient comprising:

an implantable nerve cuff configured to at least partially wrap around a segment of a Hypoglossal nerve (HGN), the nerve cuff including a plurality of electrodes each oriented and configured to contact the HGN at different radial locations of the segment of the HGN;

an implantable core subsystem electrically coupled to the nerve cuff; and

an external controller in communication with the implantable core subsystem and configured to control electrical stimulation applied to the HGN through the plurality of electrodes.

46. The implantable neurostimulator ofclaim 45, wherein the core subsystem includes a printed circuit board (PCB).

47. The implantable neurostimulator ofclaim 46, wherein the core subsystem includes a radio frequency (RF) interface electrically coupled to the PCB and in RF communication with the controller.

48. The implantable neurostimulator ofclaim 45, wherein the controller is configured to initiate a stimulation cycle of the HGN.

49. The implantable neurostimulator ofclaim 48, wherein the initiation of the stimulation cycle is conditional on one or more of activity and posture of the patient determined by a sensor in communication with the controller.

50. The implantable neurostimulator ofclaim 45, wherein the core subsystem is configured to report completion of a stimulation state to the controller and then go to an idle state.

51. The implantable neurostimulator ofclaim 45, wherein at least two of the plurality of electrodes are arranged at different longitudinal positions with respect to the HGN when the nerve cuff is wrapped around the HGN.

52. The implantable neurostimulator ofclaim 45, wherein the nerve cuff is configured to completely radially wrap around the segment of the HGN.

53. The implantable neurostimulator ofclaim 45, wherein the plurality of electrodes are configured to provide continuous open loop electrical stimulation to the HGN during sleep hours.

54. The implantable neurostimulator ofclaim 45, wherein the nerve cuff is configured to deliver multiple modes of stimulation.

55. The implantable neurostimulator ofclaim 45, wherein the plurality of electrodes are configured to provide bi-phasic stimulation of the HGN.

56. The implantable neurostimulator ofclaim 45, wherein the controller is configured to stimulate patient specific nerve physiology and stimulation parameters.

57. The implantable neurostimulator ofclaim 45, wherein the plurality of electrodes are programmable to maximize rate of airflow and stability of the upper airway.

58. The implantable neurostimulator ofclaim 45, wherein the plurality of electrodes are configured to provide stimulation to different fascicles of HGN at preprogrammed conditions.

59. The implantable neurostimulator ofclaim 45, wherein each of the plurality of electrodes is oriented and configured to contact a different web of nerve fascicles of the HGN.

60. The implantable neurostimulator ofclaim 45, wherein the plurality of electrodes are configured and arranged to enable selective stimulation of both lateral HGN branches.

61. The implantable neurostimulator ofclaim 45 further comprising:

a multiplexer electrically coupled to the plurality of electrodes, the multiplexer being programmable and configured to enable selective stimulation of particular areas of the HGN.

62. An implantable neurostimulator system for treating obstructive sleep apnea, comprising:

an implant configured to at least partially surround a portion of a Hypoglossal nerve (HGN);

a printed circuit board (PCB) electrically coupled to the implant;

a neural interface electrically coupled to the PCB;

a core subsystem (CSS) electrically coupled to the PCB and electrically connected to the neural interface, the core subsystem being configured to select a trained waveform from memory and start stimulation by providing an electrical signal to the neural interface upon receiving a request to enter into a stimulation state, the core subsystem being configured to report completion of a stimulation state to the controller via an RF communication and go to an idle state;

a radio frequency (RF) interface electrically coupled to the PCB and electrically coupled to the CSS; and

an external programmable controller configured to power and control the implant.

63. An implantable neurostimulator system for treating obstructive sleep apnea, comprising:

an implant configured to and at least partially surround a portion of the Hypoglossal nerve (HGN);

a printed circuit board (PCB) electrically coupled to the implant;

a neural interface electrically coupled to the PCB;

a core subsystem (CSS) electrically coupled to the PCB and electrically coupled to the neural interface, the core subsystem being included in a silicon chip placed on the PCB with the chip connected to the neural interface via traced wires printed on the PCB;

a radio frequency (RF) interface attached to the first side of the PCB and electrically coupled to the CSS; and

an external programmable controller configured to power and control the implant.

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