US20080065173A1 - Headset recharger for cranially implantable medical devices - Google Patents

Abstract

The invention is directed to a recharging system and associated techniques to recharge an implantable medical device (IMD). In particular, a recharging system according to the invention comprises a headset having an energy delivery module that delivers energy to a power source of an IMD implanted on or within the cranium of a patient. The energy delivery module may comprise a coil for inductive transfer of energy to the power source. The headset may be configured for placement over the head of the patient, and may further only partially cover the top of the head. The energy delivery module may be adjustably coupled to the headset. In some embodiments, the position of the energy delivery module may be adjusted along three or four axes, including a rotational axis, allowing the coil to be placed over an IMD located at any of a variety of locations on or within the cranium.

Description

• This application is a divisional of U.S. patent application Ser. No. 10/835,548, filed Apr. 29, 2004, which claims the benefit of U.S. Provisional Application Ser. No. 60/471,262, filed May 16, 2003. The entire contents of U.S. patent application Ser. No. 10/835,548 and U.S. Provisional Application Ser. No. 60/471,262 are incorporated herein by reference.
TECHNICAL FIELD
• The invention relates to medical devices, and more particularly, to techniques for recharging power sources of implantable medical devices.
BACKGROUND
• Depending on the application for which they are implanted in a patient, implantable medical devices (IMDs) may include a variety of electrical and/or mechanical components. Typically, an IMD includes a rigid housing that houses all of its components, which are generally fragile, to protect the components from forces to which they would otherwise be exposed when implanted within the human body. In order to avoid potentially harmful interactions between the components and bodily fluids, e.g., corrosion, IMD housings are typically hermetically sealed. Many IMD housings are fabricated from Titanium because of its desirable rigidity and biocompatibility. Components common to most IMDs include a hybrid circuit that includes digital circuits, e.g., integrated circuit chips and/or a microprocessor, and analog circuit components. Most IMDs also include a battery to provide power to the digital and analog circuit components.
• Most IMDs rely on a non-rechargeable, e.g., primary, battery as a source of power. When a primary battery is no longer able to provide adequate power for an IMD, the IMD must be explanted, and either the battery or the entire IMD must be replaced. The “lifetime” of a primary battery depends on the power requirements of the IMD, and the amount of power stored by the battery. The amount of power stored by a battery is closely related to its size, while the amount of power required by an IMD is primarily dependent of the type of therapy delivered by the IMD. For example, implantable neurostimulators and implantable pumps consume power at a relatively higher rate than cardiac pacemakers and IMDs used primarily for patient monitoring. Consequently, designers of IMDs with high power requirements, such as implantable neurostimulators and implantable pumps, often must choose between use of an undesirably large primary battery, or potentially exposing the patient to the risks associated with an eventual surgical procedure to explant the current IMD and implant a new IMD.
• In response to the problems associated with the use of primary batteries, some IMDs with high power consumption have been configured as “radio frequency” (RF) systems in which the IMD does not include an implanted power source, but instead receives power from an external power source via transcutaneous inductive energy transfer. Typically the external power source includes a rechargeable battery and is coupled to a primary (external) coil, and the IMD includes or is coupled to a secondary (implanted) coil. Because the IMD in such systems does not include an internal power source, the patient must always wear, or otherwise carry, the external power source, and must keep the primary coil proximate to and aligned with the secondary coil at all times. Further, the patient may periodically have their movement restricted while the external power source is recharged, e.g., via a wall receptacle. On the whole, patients may view such systems as burdensome and restricting.
• Other IMDs have been configured to include a rechargeable power source, e.g., a rechargeable battery, within the IMD. Typically, the rechargeable power source is periodically recharged by an external power source, i.e., a recharging device, via transcutaneous inductive energy transfer. Rechargeable batteries used in IMDs may have a longer lifetime and/or a smaller size than primary batteries. Further, when an IMD uses a rechargeable battery, the patient is free to move without the recharging device between recharging sessions.
• The effectiveness of the recharging sessions, e.g., the time required to recharge the rechargeable battery, is dependant upon a number of considerations, such as the amplitude and frequency of the current induced in the secondary coil. The amplitude of the current induced in the secondary coil is, in turn, dependent of the proximity and alignment of the primary and secondary coils. Conventional IMD recharging devices may make it difficult for the patient to properly align the primary coil with the secondary coil, and/or to maintain proper alignment during a recharging session. Patients may have particular difficulty achieving and maintaining proper alignment for recharging where their IMD is implanted on or within their cranium. In particular, patients may have difficulty properly aligning the coils on a part of the body which they can see, if at all, only with the aid of a mirror. Further, traditional means for maintaining alignment of the coils during a recharge session, e.g., an adhesive patch carrying the primary coil, may be ineffective in cases in which the IMD is located beneath the patient's hair.
SUMMARY
• In general, the invention is directed to a recharging system and associated techniques to recharge a power source of an implantable medical device (IMD) that is implanted on or within a cranium of a patient. In particular, the recharging system comprises a headset having an energy delivery module coupled to the headset. In some embodiments, the energy delivery module comprises a primary coil that delivers energy to the power source of the IMD via transcutaneous inductive energy transfer to a secondary coil associated with the IMD. The headset may be configured for placement over the head of the patient, may only partially cover the top of the patient's head, and the size of the headset may be adjusted in the manner traditionally associated with audio headphones.
• The energy delivery module may be adjustably coupled to the headset to allow alignment with a recharge module, e.g., a secondary coil, associated with the IMD. The recharge module may be located within the IMD, substantially co-located with the IMD, or may be located some distance from the IMD. In some embodiments, the energy delivery module is coupled to the headset by a coupling member, which is adjustably coupled to the headset to allow the position of the energy delivery module to be adjusted. In exemplary embodiments, the position of the energy delivery module is adjustable along at least two axes and, in some embodiments, is adjustable along three or four axes including a rotational axis.
• The coupling member may include a first end coupled to the headset and a second end coupled to the energy delivery module. The adjustable coupling of the coupling member to the headset may permit lateral, posterior, and anterior movement of the energy delivery module with respect to the head of the patient. The coupling member may further pivot about the point at which it is coupled to the headset to permit rotational motion of the energy delivery module. In some embodiments, the coupling member may be malleable or made malleable, e.g., via the application of heat, and the may be formed, e.g., molded, to the curvature of the patient's head.
• The coupling member may be coupled to the headset by a fixation mechanism. The fixation mechanism may be adjusted between a first state in which the position of the energy delivery module may be adjusted, and a second state in which the position of the energy delivery module is substantially fixed. The fixation mechanism may be, for example, a nut and bolt mechanism.
• A stabilizing member may also be coupled to and/or extend from the headset to stabilize the position of the headset on the head of the patient. In some embodiments, the position of stabilizing member may be adjusted and fixed via a fixation mechanism as described above with reference to the coupling member. In some embodiments, the stabilizing member may be malleable or made malleable, e.g., via the application of heat, and the may be molded to the curvature of the patient's head.
• The recharging system may further include a recharge control unit that controls the delivery of energy to the power source of the IMD. In some embodiments, the recharge control unit includes a rechargeable battery, and controls delivery of energy from the rechargeable battery to the power source of the IMD.
• The recharge control unit may also include a telemetry circuit that is coupled to a telemetry antenna, which is in turn coupled to the headset, and the recharge control unit may communicate with the IMD via the telemetry antenna and telemetry circuit. The recharge control module may receive recharge status information from the IMD, such as an indication of the current charge level of the IMD power source or an indication that the IMD power source is fully recharged. In some embodiments in which the energy delivery module comprises a primary coil, the telemetry antenna may comprise the primary coil. In other embodiments, the telemetry antenna may be coupled to the headset by same adjustable coupling member as the energy delivery module, or a different adjustable coupling member than that which couples the energy delivery module to the headset.
• The recharge control unit may also include a user interface, and may provide information to the patient via the user interface. For example, the recharge control module may provide alignment information to the patient, such as an indication when the energy delivery module is properly aligned with a recharge module of the IMD. As another example, the recharge control module may provide recharge status information, such as an estimated time remaining for the recharge session, an indication of extent to which the IMD power source is currently charged, or an indication that the power source is fully recharged and the recharge session is complete. The user interface may include a speaker and/or a display, and the recharge control unit may present the information to the patient audibly and/or visually. In some embodiments, the patient may also control initiation and/or termination of energy delivery via the user interface. In some embodiments, the recharge module may store files for patient entertainment, such as MP3 song files, and may play files selected by the patient via the user interface during a recharge session. In some embodiments, the headset may include one or more earpieces that include a speaker, and the recharge control device may audibly present information to the patient and play audio entertainment files via the speakers.
• In some embodiments, the recharge control module is housed separately from the headset, and coupled to at least one of the headset and the energy delivery module via a conductor, e.g., a cable. In such embodiments, the recharge control module may be configured to be worn by the patient, e.g., may be configured to be attached to a belt or other clothing of the patient. In other embodiments, the recharge control module may be integrated with the headset. For example, in embodiments in which the headset includes one or more earpieces, the recharge control module may be included within a single earpiece, or the components of the recharge control may be distributed between two earpieces.
• The IMD may be, for example, an implantable neurostimulator or implantable pump. In some embodiments, the IMD takes the form of a modular IMD in which components of the IMD, such as control electronics, the power source, and a recharge module, e.g., a secondary coil, are housed within separate modules. Because its components are distributed into a plurality of modules, a modular IMD may have a low profile that provides cosmetic, patient comfort, and clinical acceptability benefits when the modular IMD is implanted on the cranium of the patient beneath the patient's scalp. However, a recharge device according to the invention may be used to recharge any medical device implanted on or within the cranium of a patient.
• In one embodiment, a system comprises a headset configured for placement over a head of a patient that partially covers a top of the head, and an energy delivery module coupled to the headset that delivers energy to a power source of a medical device that is implanted at least one of on or within a cranium of the patient.
• In another embodiment, a system comprises a headset that is configured for placement over a head of a patient, and an energy delivery module that is adjustably coupled to the headset, and that delivers energy to a power source of a medical device that is implanted at least one of on or within a cranium of the patient.
• In another embodiment, a method comprises placing a headset on a head of a patient, adjusting a position of an energy delivery module that is coupled to the headset to locate the energy delivery module proximate to a medical device implanted at least one of on or within a cranium of the patient, and adjusting a fixation mechanism to substantially fix the energy delivery module in a position proximate the medical device.
• In another embodiment, a method comprises delivering energy to a power source of a medical device implanted at least one of on or within a cranium of a patient via an energy delivery module coupled to a headset that is proximate to the medical device when the headset is placed on a head of the patient.
• In another embodiment, the invention is directed to a system that includes a medical device and a recharging system. The medical device includes a power source, is implanted at least one of on or within a cranium of a patient, is coupled to a lead that is implanted at least one of within or adjacent to a brain of the patient, and at least one of delivers stimulation to the brain or monitors electrical activity within the brain via the lead. The recharging system includes a headset that is configured for placement over a head of the patient, and an energy delivery module that is adjustably coupled to the headset and delivers energy to the power source of the medical device.
• In another embodiment, the invention is directed to a system that includes a medical device and a recharging system. The medical device includes a rechargeable battery. The recharging system includes a headset that is configured for placement over a head of the patient, and an energy delivery module that is adjustably coupled to the headset and delivers energy to the power source of the medical device.
• The invention may be capable of providing one or more advantages. For example, in embodiments in which a recharging system includes an energy delivery module that is adjustably coupled to the headset, the energy delivery module may be positioned proximate to an IMD, e.g., a recharge module of the IMD, located at any of a variety of positions on or within the cranium of a patient. Further, the position of the energy delivery module may be adjusted to align the energy delivery module with the recharge module, and therefore to provide for efficient recharging of the IMD. In some embodiments, the energy delivery module may be substantially fixed in a desired position, so that proper alignment may be maintained during a recharging session. Further, in some cases, the position of the energy delivery module may be adjusted and fixed once, e.g., by a clinician during a fitting session at a clinic, and recharging system may be used by the patient at home without further adjustment of the position of the energy delivery module for the life of the IMD. By providing adjustability, the recharge system may charge IMDs implanted in a variety of implant locations for treatment or monitoring of a variety of conditions and to further account for the anatomical differences between patients. Moreover, the adjustable recharge system may replace many implant location and patient dependant recharge systems by providing a “one-size-fits-all” recharge approach.
• In embodiments of the recharging system in which the headset is coupled to or includes a stabilizing member, the stabilizing member may stabilize the position of the headset on the patient's head. The stabilizing member may facilitate consistent alignment of the energy delivery module with the recharge module of the IMD. In particular, the stabilizing member may allow the headset to be consistently placed at a position on the patient's head, and may prevent movement of the headset on the patient's head during recharging sessions. The stabilizing member may be adjusted and fixed, and/or molded, during a fitting session. Further, the size of the headset, e.g., the length of an arc defined by the headset, may be adjusted and fixed based on the size of the patient's head during a fitting session.
• Since the headset may only partially cover the head of the patient, the headset may be more comfortable to wear while charging the IMD. Furthermore, in some embodiments, the recharge control unit is incorporated into the headset, e.g., one or more earpieces of the headset, providing a single recharge device that is hands-free. In other embodiments, the recharge control unit may be a separate device that is electrically coupled to the headset, and may feature a more extensive user interface including a display. In such embodiments, the more extensive user interface may allow the patient to more easily interact with the recharge control unit.
• The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a conceptual diagram illustrating an example recharging system that recharges a power source of an implantable medical device (IMD) implanted on the cranium of a patient.
• FIG. 2 is a top-view diagram further illustrating the IMD ofFIG. 1 implanted on cranium of the patient.
• FIGS. 3A-3C are top-view diagrams illustrating exemplary headsets placed upon the head of the patient.
• FIGS. 4A-4B are top-view and rear-view diagrams, respectively, further illustrating the exemplary headset ofFIG. 3A.
• FIG. 5 is a functional block diagram illustrating the recharge control unit ofFIG. 1.
• FIG. 6 is a flow diagram illustrating an exemplary process by which a clinician fits a headset of a recharging system to a patient.
• FIG. 7 is a flow diagram illustrating an exemplary process for recharging an IMD implanted upon the cranium of a patient.
• FIG. 8 is a conceptual diagram illustrating another example recharging system that recharges a power source of an implantable medical device (IMD) implanted on the cranium of a patient.
• FIG. 9 is a conceptual diagram illustrating a recharge cradle shaped in the form of a head to recharge a rechargeable battery of the headset ofFIG. 8.
DETAILED DESCRIPTION
• FIG. 1 is a conceptual diagram illustrating anexample recharging system2 that recharges a power source (not shown) of an implantable medical device (IMD)14 implanted on the cranium of apatient18. As illustrated inFIG. 1,system2 includes aheadset10 configured for placement on thehead16 ofpatient18, and anenergy delivery module12 coupled toheadset10 that delivers energy to recharge the power source ofIMD14. As will be described in greater detail below,energy delivery module12 is adjustably coupled toheadset10 such thatenergy delivery module12 may be positioned aboveIMD14 for efficient delivery of energy to recharge the power source ofIMD14. In exemplary embodiments,energy delivery module12 comprises a primary coil formed of windings of copper or another highly conductive material that delivers energy to the power source ofIMD14 via transcutaneous inductive energy transfer to a secondary coil associated withIMD14. The power source ofIMD14 may be, for example, a rechargeable battery or supercapacitor.
• As shown inFIG. 1,headset10 is electrically coupled to arecharge control unit20 via one or more conductors carried bycable22. In other embodiments,cable22 is coupled directly to energy delivery module.Recharge control unit20 contains circuitry, such as a processor, that controls delivery of energy to the power source ofIMD14 viaenergy delivery module12. In some embodiments, the recharge control unit includes a rechargeable battery, and controls delivery of energy from the rechargeable battery to the power source of the IMD viaenergy delivery module12.
• Recharge control unit20 may further include a user interface with whichpatient18 may interact to activate, monitor and terminate the recharging ofIMD14 as well as other components (not shown), such as a telemetry circuit for communicating withIMD14 via an antenna that may be, for example, coupled toheadset10 or located withinrecharge control unit20.Recharge control unit20 may receive information relating to the status of the rechargeable power source ofIMD14 fromIMD14 via the telemetry circuit and antenna during recharging, such as an indication of the current charge level of the power source or an indication that the power source is fully recharged. In some embodiments in whichenergy delivery module12 comprises a primary coil, the antenna may comprise the primary coil. While shown as a separate fromheadset10, the components ofrecharge control unit20 may be incorporated intoheadset10 by distributing the circuitry, user interface, and other components within earpieces coupled toheadset10 or within a headset bar ofheadset10 that supportsenergy delivery module12. The headset bar, in these embodiments, may be hollow and store the circuitry in the form of flex tape circuits and capacitors, which may reduce weight and provide for even weight distribution of the components withinheadset10.
• A clinician orpatient18 may adjust the position ofenergy delivery module12 to alignenergy delivery module12 with a recharge module, e.g., a secondary coil in embodiments in whichenergy delivery module12 comprises a primary coil, associated withIMD14. The recharge module may be housed within or coupled toIMD14. The efficiency of the delivery of energy fromenergy delivery module12 to the power source ofIMD14 may depend on the degree to whichenergy delivery module12 is aligned with the recharge module ofIMD14.Patient18 or the clinician may also adjust the size ofheadset10 to fit thehead16 ofpatient12 in the manner traditionally associated with audio headphones, and may adjust and/or mold a stabilizing member (not shown) that extends fromheadset10, as will be described in greater detail below. In some embodiments, a clinician may initially make these adjustments toheadset10 and substantially fix headset in a desired configuration during a fitting session at a clinic, andpatient18 may be able to userecharging system2 at home without further adjustment for substantially the life ofIMD14.
• During use,patient18places headset10 uponhead16 to begin recharging the power source ofIMD14.Patient18 may, via interactions with a user interface ofrecharge control unit20, initiate the delivery of energy to the power source ofIMD14 viaenergy delivery module12.Recharge control unit20 may receive information concerning the status ofIMD14, and more particularly, the status of the power source included withinIMD14, via telemetry during recharging. Once the status of the rechargeable battery indicates a full charge,recharge control unit20 may terminate energy delivery and signalpatient18, e.g., issue a tone or beep, that the recharge is complete, andpatient18 may removeheadset10. In some embodiments,patient18 may by able to directrecharge control unit20 to terminate or suspend recharging during a session through interaction with the user interface ofrecharge control unit20.
• In some embodiments,recharge control unit20 may communicate with one or more programming devices, such as one or more of aclinician programmer19 and apatient programmer21 illustrated inFIG. 1.Clinician programmer19 andpatient programmer21 may, as shown inFIG. 1, be handheld computing devices.Programmers19,21 may includes displays, such as a LCD or LED displays, to display information to a user, and may also include keypads, which may be used by a user to interact with the programmers. In some embodiments, the displays may be touch screen displays, and a user may interact with the programmers via their display. A user may also interact with one or both ofprogrammers19,21 using a peripheral pointing device, such as a stylus or mouse. A clinician (not shown) may useclinician programmer19 to program aspects of the delivery of therapy topatient18 byIMD14, andpatient18 may usepatient programmer21 to control aspects of the delivery of therapy byIMD14.
• One or both ofprogrammers19,21 may communicate withrecharge control unit20 to exchange recharge information withrecharge control unit20. For example, a user, such as a clinician, may use one ofprogrammers19,21 to select one or more values used byrecharge control unit20 to control recharging ofIMD14, such as a recharging rate, or a frequency for AC voltage provided to a primary coil in embodiments in whichenergy delivery module12 comprises a primary coil. Additionally, the user may use one ofprogrammers19,21 to configure a user interface ofrecharge control unit20, e.g., to set select the types and formats of indications provided topatient18 during recharging.
• Further, a user, such as a clinician, may use one ofprogrammers19,21 to collect recharge information fromrecharge control unit20, such as information indicating the duration of one or more recharging session, the quality of alignment betweenenergy delivery module12 andIMD14, the rate at which the power source ofIMD14 was recharged, and the status of the power source ofIMD14.
• Programmers19,21 may communicate withIMD14,recharge control unit20, and each other via wireless communication.Programmers19,21 may, for example, communicate via wireless communication withIMD14 using radio frequency (RF) telemetry techniques known in the art.Programmers19,21 may communicate with each other and rechargecontrol unit20 using any of a variety of local wireless communication techniques, such as RF communication according to the 802.11 or Bluetooth specification sets, infrared communication according to the IRDA specification set, or other standard or proprietary telemetry protocols.
• Programmers19,21 andrecharge control unit20 need not communicate wirelessly, however. For example,programmers19,21 andrecharge control unit20 may communicate via a wired connection, such as via a serial communication cable, or via exchange of removable media, such as magnetic or optical disks, or memory cards or sticks. Further,programmers19,21 may communication with each other,IMD14, and rechargecontrol unit20 via remote telemetry techniques known in the art, communicating via a local area network (LAN), wide area network (WAN), public switched telephone network (PSTN), or cellular telephone network, for example.
• FIG. 2 is a top-view diagram further illustratingIMD14 implanted on thecranium23 ofpatient18. In order to implantIMD14 oncranium23, anincision24 is made through the scalp ofpatient18, and a resulting flap of skin is pulled back to expose the desired area ofcranium23. The incision may, as shown inFIG. 2, be generally shaped like a “C,” and such an incision is commonly referred to as a “C-flap” incision.
• Holes26A and26B (collectively, “holes26”) are drilled throughcranium23, and leads28A and28B (collectively, “leads28”) are inserted through holes26 into the brain ofpatient18. Caps may be placed over holes26 as is known in the art. Leads28 are connected toIMD14, either directly or via lead extensions, andIMD14 may be partially placed within a pocket formed using a hand or tool beneath the scalp behind holes26.
• Once positioned as desired oncranium23 within the pocket,IMD14 may be fixed tocranium16 using attachment mechanisms (not shown), such as bone screws. The skin flap may be closed overIMD14, andincision24 may be stapled or sutured. The location oncranium23 at whichIMD14 is illustrated as implanted inFIG. 2 is merely exemplary, andIMD14 can be implanted anywhere on the surface ofcranium23.
• IMD14 may deliver stimulation to the brain ofpatient18 to, for example, provide deep brain stimulation (DBS) therapy, or to stimulate the cortex of the brain. Cortical stimulation may involve stimulation of the motor cortex.IMD14 may be used to treat any nervous system disorder including, but not limited to, epilepsy, pain, psychological disorders including mood and anxiety disorders, movement disorders (MVD), such as, but not limited to, essential tremor, Parkinson's disease, and neurodegenerative disorders.IMD14 may be employed with leads28 deployed anywhere in the head or neck including, for example, leads deployed on or near the surface of the skull, leads deployed within the brain, e.g., deep brain leads, or leads deployed beneath the skull and adjacent to the brain, e.g., cortical leads. As other examples,IMD14 may be employed with leads28 deployed near or on the dura mater, leads placed adjacent cranial or other nerves in the neck or head, or leads placed directly on the surface of the brain.
• IMD14 is not limited to embodiments that deliver stimulation. For example, in someembodiments IMD14 may additionally or alternatively monitor one or more physiological parameters and/or the activity ofpatient18, and may include sensors for these purposes. Where a therapy is delivered,IMD14 may operate in an open loop mode (also referred to as non-responsive operation), or in a closed loop mode (also referred to as responsive).IMD14 may also provide warnings based on the monitoring. Further, in some embodimentsmodular IMD14 can additionally or alternatively deliver a therapeutic agent topatient18, such as a pharmaceutical, biological, or genetic agent.IMD14 may be coupled to a catheter, and may include a pump to deliver the therapeutic agent via the catheter.
• In the embodiment illustrated inFIG. 2,IMD14 takes the form of a modular IMD that delivers neurostimulation topatient18. In the illustrated example,IMD14 includes arecharge module30, apower module32, and acontrol module34.Recharge module30 may include, for example, a secondary coil formed of windings of copper or another highly conductive material used to receive energy from a primary coil via transcutaneous inductive energy transfer. For transcutaneous inductive energy transmission, recharge control unit20 (FIG. 1) may present an alternating current (AC) voltage to a primary coil withinenergy delivery module12, which induces an AC voltage on the secondary coil withinrecharge module30.
• Power module32 includes the rechargeable power source ofIMD14, e.g., a rechargeable battery.Control module34 includes control electronics, e.g., a microprocessor, that control the functioning ofIMD14, e.g., control delivery of neurostimulation therapy topatient18. Each ofmodules30,32, and34 may include a separate housing to protect the elements therein, and the modules may be coupled by one or more conductors, or the like. In exemplary embodiments, the housings ofmodules32 and34 may be hermetic.
• In some embodiments,recharge module30 is electrically coupled to controlmodule34, andcontrol module34 includes electronics to receive energy collected byrecharge module30, and control delivery of the energy topower module32 in order to recharge the power source therein. For example, in embodiments in which recharge module comprises a secondary coil on which an AC voltage is induced via transcutaneous inductive energy transfer,control module34 may include a rectifier circuit to convert the AC voltage to a direct current (DC) voltage. In such embodiments,control module34 provides the DC voltage to the power source ofpower module32 to recharge the power source.
• The control electronics withincontrol module34 may also include or be coupled to one or more sensors that sense the status, e.g., voltage or temperature, of the power source withinpower module32. The sensors may be located withinpower module32 orcontrol module34. The control electronics may determine the status of the power source based on signals generated by the one or more sensors.Control module34 may include a telemetry circuit and antenna, and the control electronics may transmit information regarding the status of the power source, e.g., recharge status information, to recharge control unit20 (FIG. 1) via the telemetry circuit and antenna. The recharge status information may include a voltage, temperature, or information determined on the basis of one or more of the voltage and temperature, such as an estimate of the extent to which the power source is recharged or the time left until the power source is fully recharged.
• In the illustrated embodiment,modules30,32 and34 are coupled to amember36, which may be made of a soft, biocompatible material.Member36 at least partially encapsulates one or more housings ofmodules30,32,34, and generally serves to provide a smooth interface between the modules and the body tissue.Member36 may integratemodules30,32 and34 into a desired form factor, but, where flexible, allow relative intermodule motion. In some embodiments,member36 incorporates mechanical features to restrict intermodule motion to certain directions or within certain ranges.Member36 may be made from silicone, and is some embodiments may be made from two or more materials of differing flexibility, such as silicone and a polyurethane. An exemplary polyurethane for this purpose is Tecothane® , which is commercially available from Hermedics Polymer Products, Wilmington, Mass.Member36 may also be referred to as an “overmold,” but use of the term “overmold” herein is not intended to limit the invention to embodiments in whichmember36 is a molded structure.Member36 may be a molded structure, or may be a structure formed by any process.
• Although described herein in the context of amodular IMD14 that delivers neurostimulation therapy, the invention is not so limited. A recharging system according to the invention may be used to recharge a power source of any type of medical device implanted on or within the cranium of a patient, e.g., an implantable neurostimulator, implantable pump, or a medical device used only for patient monitoring or sensing. Further, a recharging system may be used to recharge non-modular IMDs, e.g., IMDs in which the components are located within a single housing.
• FIG. 3A is top-view diagram illustrating anexemplary headset36A placed upon thehead16 of thepatient18. Anenergy delivery module38, e.g., a primary coil, is adjustably coupled toheadset36A. In embodiments in whichenergy delivery module38 comprises a primary coil, the coil may be surrounded by a housing formed of a material that permits induction, e.g., may be encapsulated in one or more of a silicone, polysulfone, polyvinylchloride, or the like. The primary coil may also act as a telemetry antenna for communication betweenrecharge control unit20 andIMD14 or, in other embodiments, a separate telemetry antenna may be stacked on top of, or below the primary coil. As described above,patient18 or a clinician may adjust the position ofenergy delivery module38 to be located above and aligned withrecharge module30 ofIMD14.
• In the illustrated embodiment,headset36A includes aheadset bar40 that wraps aroundhead16 and supports both ofearpieces42A and42B (collectively, “earpieces42”), acoupling member44, and a stabilizingmember46. The illustrated shapes, sizes, and positions ofheadset bar40, earpieces42,coupling member44 and stabilizingmember46 are merely exemplary. Further, headsets according to the invention may include any number of, or may exclude, earpieces42,coupling members44 and stabilizingmembers46.
• Headset bar40 may provide an inward pressure on earpieces42 so as to secureheadset36A to head16.Headset36A may be adjusted to the size ofhead16 by lengthening and shortingheadset bar40 to adjust the position of earpieces42 in relation to the ears of the patient to ensure a proper fit, similar to conventional audio headsets known in the art. As shown inFIG. 3A,headset36A only partially covers thehead16, and thus may be more comfortable forpatient18 to wear during recharging sessions.
• Headset bar40 andcoupling member44 may be hollow or otherwise formed to allow electrical conductors, e.g., cables, to be inserted within or routed alongheadset bar40 andcoupling member44. For example, conductors carried byheadset bar40 andcoupling member44 may deliver AC voltages fromcable22 that is coupled to earpiece42A to a primary coil included withinenergy delivery module38. As another example, in some embodiments in which a telemetry antenna does not comprise a primary coil, a separate telemetry antenna may be carried by coupling member for location aboveIMD14, e.g., withinenergy delivery module38. In such embodiments, conductors carried byheadset bar40 andcoupling member44 may electrically couple the telemetry antenna to a telemetry circuit withinrecharge control unit20. In other embodiments,headset bar40, as mentioned above, may further house at least come of the components ofrecharge control unit20 in the form of flex tape circuits, capacitors and other such electrical circuits and components in order to improve the weight distribution ofheadset36A.
• Earpieces42 may each comprise a speaker (not shown) to allowpatient18 to listen to audio provided byrecharge control unit20. Earpieces42, while shown inFIG. 3A as completely covering the ears ofpatient18, may not completely cover the ears or may include holes to allowpatient18 to hear ambient sound normally without restriction by earpieces42. As described below, earpieces42 may house at least some of the components ofrecharge control unit20. While shown inFIG. 3A to include earpieces42,headset36A may not include earpieces42 and may rely on the inward pressure provided byheadset bar40 to secureheadset36A to head16. In other embodiments,headset36A may include behind the ear members and other such earpiece replacements to secureheadset36A to head16.
• In the illustrated embodiment,coupling member44 carriesenergy delivery module38, and may be adjustably coupled toheadset bar40 by a fixation mechanism (not shown), such as a bolt and nut mechanism. In other words, couplingmember44 adjustably couplesenergy delivery module38 toheadset bar40. Couplingmember44 may be moved laterally, anteriorly, and posteriorly, as shown by the horizontal and vertical arrows, respectively. Moreover, in some embodiments,coupling member44 may pivot about it point of attachment withheadset bar40, as shown by the semi-circular arrow. Couplingmember44 may also be formed of a material that is semi-flexible or malleable, e.g., when heated, to enable a physician tomold coupling member44 to fit the curvature ofhead16. Alternatively,coupling member44 may include a piece of malleable metal cased in a plastic that enables couplingmember44 to be molded. In this instance, the piece of metal may not extend the entire length ofcoupling member44 so as not to interfere with the transmissions ofenergy delivery module38.
• Through movement ofcoupling member44,patient18 or a clinician may, for example, adjust the position ofenergy delivery module38 along at least two axes, along three axes including a rotational axis, or four axes including the vertical axis in embodiments in whichcoupling member44 may be molded. Couplingmember44 may be adjusted to allowenergy delivery module38 to be placed over and aligned with arecharge module30 of anIMD14 located at any of a variety of locations on or within the cranium ofpatient18. In this manner,headset36A may recharge an IMD, such asIMD14, implanted in a variety of implant locations, as well as allow placement ofenergy delivery module38 to account for anatomical differences between patients. For example,coupling member44 may be adjusted to allow placement of energy delivery module over a anIMD14 implanted on the crown ofcranium23 ofpatient18, in the manner illustrated inFIG. 2, or, for example, on the occipital or temporal regions ofcranium23.
• Stabilizingmember46 stabilizesheadset36A onhead16 ofpatient18. Stabilizingmember46 extends down the back ofcranium16 and aidspatient18 in properly placingheadset36A onhead16, e.g., enablesheadset36A to be placed at a consistent position onhead16, and may prevent movement ofheadset36A onhead16 during recharging sessions. In this manner, stabilizingmember46 may facilitate consistent alignment ofenergy delivery module38 withrecharge module30 ofIMD14.
• Stabilizingmember46 may be formed of a material that is semi-flexible or malleable, e.g., when heated, to enable a physician to mold stabilizingmember46 to fit the curvature ofhead16. Like couplingmember44, stabilizingmember46 may include a piece of malleable metal cased in a plastic that enables stabilizingmember46 to be molded. Alternatively, a number of stabilizing members formed of rigid materials may be pre-formed, and a clinician may select a stabilizing member that most closely matches the form ofhead16. Stabilizingmember46 may be permanently affixed toheadset bar40, e.g., may be a protrusion that extends fromheadset bar40, or may be coupled to headset bar as required by a clinician using a fixation mechanism similar to that used to couple couplingmember44 toheadset bar40. While shown affixed posteriorly, stabilizingmember46 may be affixed anteriorly and may further be of any size or shape. Stabilizingmember46 may be adjusted and fixed, and/or molded, by a clinician during a fitting session.
• FIG. 3B is a top-view diagram illustrating anotherexemplary headset36B placed uponhead16 ofpatient18.Energy delivery module38 is adjustably coupled toheadset bar40 by couplingmember44, as described above with reference toheadset36A andFIG. 3A. Additionally, in the illustrated embodiment, atelemetry antenna48 is adjustably coupled toheadset bar40 by asecond coupling member49.
• Couplingmember49 may be affixed toheadset bar40 via a fixation mechanism, such as a nut and bolt mechanism, which may be the same fixation mechanism used to couple couplingmember44 toheadset bar40, or a different fixation mechanism. Similar to couplingmember44,coupling member49 may also be hollowed or otherwise configured to carry conductors that electricallycouple telemetry antenna48 to a telemetry circuit withinrecharge control unit20, and may be malleable. Couplingmember49 may be adjusted bypatient18 or a clinician similarly to couplingmember44 so as to positiontelemetry antenna48 aboveIMD14 located anywhere on or withincranium23 of patient. In this manner,headset36B may possibly provide for more efficient data communications and energy deliver sincetelemetry antenna48 andenergy delivery module38 may be more accurately positioned aboveIMD14. For example,energy delivery module38 may be positioned above and aligned withrecharge module30 ofIMD14, whiletelemetry antenna48 is positioned above a telemetry antenna included withincontrol module34 ofIMD14. Aheadset36B withenergy delivery module38 andtelemetry coil48 that are separately positionable may be particularly useful in conjunction with embodiments ofIMD14 in which rechargemodule30 andcontrol module34 ofIMD14 are located a significant distance from each other, e.g., whenrecharge module30 is located a significant distance from and “tethered” toother modules32,34 ofIMD14.
• FIG. 3C is a top-view diagram illustrating yet anotherexemplary headset36C placed uponhead16 ofpatient18. Similar toheadset36B ofFIG. 3B,headset36C includes anenergy delivery module38 andseparate telemetry antenna48, howeverheadset36C includes only onecoupling member44.Energy delivery module38 andtelemetry antenna48 may be encased in acommon housing member50, as shown inFIG. 3C.
• Housing member50 may, in some embodiments, be formed of a material that is semi-flexible or malleable, e.g., when heated, to enable a physician to moldhousing member50 to conform to the curvature ofhead16.Housing member50 couples to an end of couplingmember44 and may rotate about the point wherehousing member50 couples to couplingmember44. Typically,housing member50 is coupled to couplingmember44 as required by a clinician using a fixation mechanism similar to that used to couple couplingmember44 toheadset bar40. In some embodiments,housing member50 is permanently affixed to couplingmember44, however this configuration may not allowhousing member50 to rotate about the point wherehousing member50 couples to couplingmember44. Rotation and molding ofhousing member50 may allow a user to placeenergy delivery module38 andtelemetry antenna48 above and proximate to rechargemodule30 andcontrol module34 ofIMD14, respectively.
• Although described above as carried by one ofcoupling members44,49, in various embodiments atelemetry antenna48 may be located anywhere on or within aheadset36. For example, in some embodiments, atelemetry antenna48 may be located within one of earpieces42 of aheadset36. In other embodiments, a telemetry antenna is not located on or withheadset36 at all, and may instead be located, for example, withinrecharge control unit20.
• FIGS. 4A-4B are top-view and rear-view diagrams, respectively illustratingheadset36A ofFIG. 3A in greater detail. In particular,FIG. 4A illustrates anexample fixation mechanism51 used to connectcoupling member44 toheadset bar40.Fixation mechanism51 may be adjusted bypatient18 or a clinician between a first state in whichcoupling member44 may be moved and a position ofenergy delivery module38 may be adjusted, and a second state in whichcoupling member44 and the position ofenergy delivery module38 are substantially fixed. As illustrated inFIG. 4B,fixation mechanism51 may include a threaded bolt-like member54 and a nut-like member55 that allow movement ofcoupling member44 when loosened, and cooperate to substantially lockcoupling member44 in a desired position when tightened.
• In the illustrated embodiment, the threaded portion of bolt-like member54 extends through ahole52 formed inheadset bar40.Hole52, as shown inFIG. 4A, may comprise an oblong hole inheadset bar40 to facilitate lateral positioning ofenergy delivery module38. Bolt-like member54 also extends through anoblong hole53 inrecharge arm44 to facilitate anterior-posterior positioning ofenergy delivery module38. Couplingmember44 may also rotate aboutfixation mechanism51 for rotational positioning of energy delivery module. In some embodiments, fixation mechanisms similar to that illustrated inFIGS. 4A and 4B, or thesame fixation mechanism51, may also be used to allow adjustment and fixation of a stabilizingmember46 or anadditional coupling member49 that carries atelemetry antenna48 withinholes52,53. The size and shapes ofholes52,53 are merely exemplary.
• Further, the type offixation mechanism51 illustrated inFIGS. 4A-4B is merely exemplary. A recharging headset according to the invention may include any type of fixation mechanism. For example, the position of couplingmember44 may fixed by a friction mechanism until coupling member is forcibly moved to another position.
• Other fixation mechanisms may include glue or set screws to permanently fixcoupling member44. In some embodiments, fixation mechanisms may include features, such as detents, included withinoblong hole53, and corresponding features included oncoupling member44. The features may interact to fix the position of couplingmember44 andenergy delivery module38. In such embodiments, the fixation mechanism may further include a mechanism, such as a lever lock, to position the one or more features associated withcoupling member44 out of the path of features included inoblong hole53, thereby allowingcoupling member44 to be positioned without obstruction. The mechanism can then reposition the features associated withcoupling member44 back in the path of the features included inoblong hole53 when couplingmember44 is properly positioned to prevent further movement ofcoupling member44.
• FIG. 5 is a block diagram illustratingrecharge control unit20 ofFIG. 1 in greater detail.Recharge control unit20, and more particularly aprocessor54 ofrecharge control unit20, controls delivery of energy from arechargeable battery56 to the power source ofIMD14 via anenergy delivery module12,38.Processor54 may take the form of a microprocessor, digital signal processor (DSP), application specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other logic circuitry.Rechargeable battery56 may be any conventional rechargeable battery, such as a Lithium-Ion rechargeable battery, Nickel-Metal Hydride rechargeable battery, or a Nickel-Cadmium rechargeable battery.
• Recharge control unit20 further includes apower management circuit55 and a modulatingcircuit58.Power management circuit55 rechargesrechargeable battery56 using an AC voltage received from aninput port60, which is coupled to an external power supply. Input port may be coupled to the power supply by placingrecharge control unit20 into a cradle that is plugged into a wall receptacle, or by pluggingrecharge control unit20 directly into a wall receptacle.Power management circuit55 or the cradle may include a step down transformer and a rectifier to convert the AC voltage into a DC voltage usable for rechargingrechargeable battery56.Rechargeable battery56 may be recharged in between recharge sessions in which the power source ofIMD14 is recharged, e.g., recharge control unit may be left in the cradle or plugged into the wall for recharging between recharging sessions.Rechargeable battery56 is merely an example of a power source and rechargecontrol unit20 may include other forms of power such as non-rechargeable batteries, fuel cells, capacitors, super capacitors, solar cells, nuclear cells, or any combination thereof.
• Modulatingcircuit58 converts a DC voltage provided bybattery56 into an AC voltage at a desired amplitude and frequency for delivery toenergy delivery module12,38. Conductors withincable22 may be coupled to modulatingcircuit58 via an I/O port62 to receive the AC voltage output by modulatingcircuit58.Processor54 controls the recharging ofrechargeable battery56 and delivery of power frombattery56 toenergy delivery module12,38 by providing control signals topower management circuit55 and modulatingcircuit58. In some embodiments,recharge control unit20 does not includerechargeable battery56, but instead includes transformer and modulator circuitry to convert an AC voltage received from a wall receptacle viainput port60 to an AC voltage with suitable amplitude and frequency for recharging ofIMD14.
• In some embodiments,recharge control unit20 includestelemetry circuit64 that allowsprocessor54 to communicate withIMD14.Telemetry circuit66 converts analog telemetry signals received fromIMD14 via a primary coil ofenergy delivery module38 or adedicated telemetry antenna48, depending on the embodiment, into digital signals for processing byprocessor54.Telemetry circuit66 may also convert digital signals fromprocessor54 into analog signals for transmission toIMD14.Cable22 may comprise conductive elements that couple the primary coil orantenna48 totelemetry circuit64 via I/O port62 whencable22 is inserted into I/O port62. In some embodiments,antenna48 is not located on or withinheadset36 as described above, andcable22 need not carry conductors to coupleantenna48 totelemetry circuit64.
• Processor54 may, for example, receive recharge status information fromIMD14 during a recharging session viatelemetry circuit64. Recharge status information may include periodic indications of the extent to which the power source ofIMD14 is currently recharged, periodic indications of the time remaining to fully recharge the power source, or an indication that the power source is fully recharged.Processor54 may control or terminate delivery of energy by modulatingcircuit58 based on one or more of these indications. In some embodiments,processor54 periodically receives voltages and/or temperatures fromIMD14, and determines the extent to which the power source ofIMD14 is currently recharged, the time remaining to fully recharge the power source, or whether the power source is fully recharged based on the voltages and/or temperatures
• Processor54 may present such recharge status information topatient18 via auser interface66.User interface66 may include, for example, a display and one or more speakers. The speakers may be included within a housing ofrecharge control unit20, or within earpieces42 ofheadset10,36 and coupled toprocessor54 bycable22 and I/O port62. For example,processor54 may present textual or graphical indications of the extent to which the power source ofIMD14 is currently recharged and/or the time remaining to fully recharge the power source via the display. As another example,processor54 may present an audible indication when the power source ofIMD14 is fully recharged via the speakers. In some embodiments,user interface66 includes input media, such as a touch screen, buttons, keypads, pointing device, or the like. In such embodiments,patient18 may control recharging, e.g. may initiate or terminate recharging, viauser interface66.
• During alignment ofenergy delivery module12,38 with arecharge module30 ofIMD14, e.g., during a headset fitting session,processor54 may receive alignment information. The alignment information may include an indication of whenenergy delivery module12,38 is properly aligned withrecharge module30, or of the relative degree to whichenergy delivery module12,38 is properly aligned arecharge module30. The alignment information may include a measure of the impedance, current or other properties at energy delivermodule12,38. In some embodiments,IMD14 communicates alignment information toprocessor54 viatelemetry antenna48, I/O port62, andtelemetry circuit64. In these embodiments, sensors withinIMD14 may measure one or more properties of the power source ofIMD14, such as current, temperature, or both, or one or more properties of therecharge module30 ofIMD14, such as impedance, current or other properties, andIMD14 communicates this alignment information toprocessor54 viatelemetry antenna48. In other embodiments,processor54 receives both alignment information gathered fromenergy delivery module12,38 and alignment information communicated viatelemetry antenna48 and processes both to generate a coupling resonant frequency, a coupling phase or other alignment information.Processor54 may present the alignment information to the aligning user, e.g.,patient18 or the clinician, viauser interface56, such an audible indication when the modules are aligned via one or more speakers, or a graphical representation of the relative alignment of the modules via a display.
• In some embodiments,recharge control unit20 includes amemory68.Processor54 may store data received fromtelemetry circuit64 inmemory68.Memory68 may also store program instructions that, when executed byprocessor54,cause processor54 andrecharge control unit20 to perform the functions ascribed to them herein.Memory68 may include any removable or non-removable magnetic, optical, or electrical media, such as one or more of a random access memory (RAM), read-only memory (ROM), CD-ROM, magnetic disk, memory stick, electronically-erasable programmable ROM (EEPROM), flash memory, or the like.
• In some of these embodiments,processor54 may be capable of playing media to, for example, entertainpatient18 during recharging sessions. For example,processor54 may include an audio module, such as an MP3 module, andmemory68 may further store audio files, such as MP3 files, that encode audio content. The audio module may play the audio files stored inmemory68 and transmit the audio content resulting from playing the audio files to I/O port62.Patient18 listens to the audio content via one or more speakers included within earpieces42. Patient may interact withprocessor54 viauser interface66 to select files for playback from among those stored inmemory68. In other embodiments,recharge control unit20 may include a radio, or a network interface to allowpatient18 to access the Internet viarecharge control unit20.Processor54 may further execute programs, such as games, stored inmemory68 that may entertain or occupypatient18.
• To use arecharging system2 to recharge a power source of anIMD14 during a recharging system,patient18places headset10 uponhead16 so as to bringenergy delivery module12,38 proximal toIMD14, and interacts withrecharge control unit20 viauser interface66 to initiate charging. Upon receiving the request to begin charging fromuser interface66,processor54causes modulating circuit58 to begin converting the DC voltage stored withinrechargeable battery56 to an AC voltage and transferring the AC voltage to I/O port62. The AC voltage travels alongcable22 intoenergy delivery module12,38. In embodiments in whichenergy delivery module12,38 comprises a primary coil, the AC voltage presented to the primary coil induces an AC voltage within a secondary coil ofrecharge module30 ofIMD14, which is used byIMD14 to recharge the power source ofIMD14, as described above.
• While charging occurs,processor54 may pollIMD14 viatelemetry circuit66 and either the primary coil or adedicated telemetry antenna48 to determine the status of the rechargeable battery withinIMD14.Processor54 may present information pertinent to the status of the rechargeable battery withinIMD14 topatient18 via a display ofuser interface64. Onceprocessor54 determines charging is complete,processor54 may causeuser interface64 to signalpatient18 that charging is complete.User interface64 may present a message indicating successful charging of the battery withinIMD14 via a display, issue a tone or beep, vibrate, or perform other such actions to signal successful charging.
• FIG. 6 is a flow diagram illustrating an exemplary process by which a user fits a headset, such asheadset36, to a patient, such aspatient18. The exemplary process illustrated inFIG. 6 may be performed bypatient18 prior to a recharging session, but is preferably performed a single time by a clinician during a headset fitting session at a clinic. Initially, the clinician placesheadset36A (FIG. 3A) upon thehead16 of patient18 (72), and adjusts the size ofheadset bar40 to the size of the head16 (74).Headset36A, as shown inFIG. 3, only partially covershead16 providing more comfort topatient18 with respect to conventional recharge mechanisms while also providing adjustability to facilitate efficient recharging of an IMD, such asIMD14, implanted on or within the cranium ofpatient18.
• In some embodiments, the clinician may determine thatpatient18 requires a stabilizingmember46 to maintainheadset36 at a desired position onhead16. The clinician determines whether to include a stabilizing member by, for example, monitoringpatient18 when placingheadset36A uponhead16. If the patient experiences difficulty correctly placingheadset36A in a consistent position onhead16, orheadset36A moves onhead16, the clinician may attach stabilizingmember46 toheadset36A with a fixation mechanism. The clinician may then adjust the position of the stabilizingmember46 and/or mold the stabilizingmember46 to fit the curvature of head16 (76). In some embodiments, the clinician may not need to form stabilizingmember46, and instead the clinician selects a stabilizing member from a plurality of options that most closely fitshead16, as described above. Further, in some embodiments, stabilizingmember46 is not a separate member fromheadset bar40, but is instead an integral protrusion fromheadset bar40.
• The clinician positionsenergy delivery module38 above arecharge module30 ofIMD14 by adjustingcoupling member44 ofheadset36A (78). As described above,coupling member44 may be moved laterally and in a posterior-anterior direction with respect topatient18. The clinician may further adjust couplingmember44 by pivotingcoupling member44 about a point of contact withheadset bar40 andmolding coupling member44. In some embodiments, as described above, the clinician may further rotate and mold a housing member that is carriesenergy delivery module38 and is coupled to couplingmember44. Upon positioningenergy delivery module38, the clinician adjusts afixation mechanism51, such as bolt-like member53 and nut-like member54, to substantially lock the position of coupling member44 (80) and thus the position ofenergy delivery module38 with respect to therecharge module30. In some embodiments, as described above, the clinician may receive alignment information via auser interface66 ofrecharge control unit20, and may use the alignment information to determine whenenergy delivery module38 is properly aligned with therecharge module30 ofIMD14.
• While fitting a headset is explained in the context ofheadset36A, the clinician may also fit a headset similar toheadset36B ofFIG. 3B. The process offitting headset36B is similar tofitting headset36A, howeverheadset36B requires an additional step to position acoupling member49 that carries atelemetry antenna48 proximal toIMD14.
• FIG. 7 is a flow diagram illustrating an exemplary process by whichpatient18 places aheadset36A (FIG. 3A), upon his or herhead16 to rechargeIMD14.Patient18 begins by placingheadset36A upon his or her head16 (86) and initiating the recharge of IMD14 (88) via user interface66 (FIG. 5) ofrecharge control unit20. Typically,patient18 initiates the recharge by selecting recharge options presented byuser interface66, however rechargecontrol unit20 may automatically begin recharging after a pre-set time limit is exceeded.
• Once the recharge is initiated viauser interface66,processor54causes modulating circuit58 to begin converting the DC voltage stored inrechargeable battery56 into an AC voltage. Modulatingcircuit58 delivers the AC voltage toheadset36A, and more particularly, toenergy delivery module38 via I/O port60 and cable22 (90). The AC voltage may, for example, be presented to a primary coil ofenergy delivery module38, and may induce an AC voltage within a secondary coil associated withIMD14, as described above.
• In further embodiments,recharge control unit20 may communicate withIMD14 via a primary coil withinenergy delivery module38, or via aseparate telemetry antenna48.Recharge control unit20 includestelemetry circuit66 to enable communication withIMD14, as described above. Via communications withIMD14,recharge control unit14 may receive recharge status information, e.g., determine whether charging ofIMD14 is complete (92). In embodiments that do not includetelemetry circuit66,processor54 may determine charging is complete after a pre-set interval of time has expired. In the event charging is not complete,processor54 continues to control delivery of energy fromrechargeable battery56 to energy delivery module38 (90).
• However, in the event the charging ofIMD14 is determined to be complete,processor54 terminates delivery of energy toenergy delivery module38, and causesuser interface64 to issue a signal topatient18 by way of one of the signaling mechanism described above that indicates to patient18 that charging is complete (94). In response to the signal,patient18 may removeheadset36A from his or her head16 (96).
• While discussed in the context of aseparate headset36A and rechargecontrol unit20,headset36A may integrate the components, such asprocessor54, ofrecharge control unit20 into earpieces42 ofheadset36A,36B. As described below, a headset incorporating the components ofrecharge control unit20 may offer a less cumbersome recharge device by eliminating the need forcable22.
• FIG. 8 is a conceptual diagram illustrating anotherexample headset104 that positions anenergy delivery module106 proximal to an implantable medical device (IMD)108 implanted on thecranium110 of apatient112. In the illustrated embodiment,headset104 incorporates the components of recharge control unit20 (FIG. 5) intoearpieces114A and114B. The components, such asprocessor54,power management circuit55,rechargeable battery56, and the like, may be distributed betweenearpieces114A and114B (collectively, “earpieces114”) to provide adequate balance and comfort when worn bypatient112. For example,right earpiece114A may includeprocessor54,power management circuit55, andtelemetry circuit66, whileleft earpiece114B includesrechargeable battery56, modulatingcircuit58 anduser interface64.Headset bar116 may be hollowed or otherwise configured to conductors that electrically couple the various components distributed between earpieces114. In all other aspects,headset104 performs in a manner substantially similar toheadset36A.
• FIG. 9 is a conceptual diagram illustrating arecharge cradle118 shaped in the form of a head to recharge a rechargeable battery, such as rechargeable battery56 (FIG. 5), ofheadset120.Headset120 may include contacts (not shown) or some other means forelectrically coupling headset120 to rechargecradle118. The contacts may be included on the earpieces ofheadset120 and may come into contact with similar contacts (not shown) included withinrecharge cradle118. Once the contacts ofrecharge cradle118 andheadset120 come into contact,recharge cradle118 may rechargeheadset120.Recharge cradle118 may plug into a transformer that is plugged directly into the wall and include electronic components, such as a rectifier, to chargeheadset120.Recharge cradle118 may also serve as a suitable location for storingheadset120 even when recharging is not required.
• Various embodiments of the invention have been described. However, one skilled in the art will appreciate that various modifications may be made to the described embodiments without departing form the scope of the invention. For example, although described herein primarily in the context of transcutaneous inductive energy transfer, other techniques for transcutaneous energy transfer may be used. In some embodiments, for example, an energy delivery module of a headset and a recharge module of an IMD may comprise ultrasonic transducers, such as piezoelectric crystals, and energy may be transferred from the energy delivery module to the recharge unit in the form of ultrasonic waves. In other embodiments, an energy delivery module of a headset and a recharge module of an IMD may comprise a light source and a photoreceptor respectively, and energy may be transferred form the energy delivery module to the recharge unit in the form of light waves. In other words, in various embodiments, the energy delivery module of a headset and the recharge module of an IMD may take the form of any type of transducers, and any form of energy may be transcutaneously transferred between them.
• Further, although described herein primarily in the context of recharging a rechargeable battery of a neurostimulator implanted on the crown of the cranium of the patient, the invention is not so limited. A recharging system according to the invention may be used to recharge any type of power source of any type of implantable medical device. Further, a recharging system according to the invention may be configured or adjusted to recharge an IMD located anywhere on or within the cranium of the patient, such as the illustrated IMD implanted on the crown of the cranium, or an IMD implanted on or under an occipital or temporal region of the cranium. These and other embodiments are within the scope of the following claims.

Claims (12)

1. A method comprising:

placing a headset on a head of a patient, wherein the headset extends from a first end to a second end;

adjusting a first position of an energy delivery module to locate the energy delivery module at a second position proximate to a medical device implanted at least one of on or within a cranium of the patient and under a scalp of the patient, thereby facilitating delivery of recharge energy from the energy delivery module to a rechargeable power source of the medical device, wherein the energy delivery module is coupled to a medial portion of the headset between the first and second ends with a coupling member that is coupled to the headset and is adjustable along at least two axes of motion; and

adjusting a fixation mechanism to substantially fix the energy delivery module at the second position proximate the medical device.

2. The method ofclaim 1, wherein the energy delivery module comprises a primary coil that delivers energy to the power source of the medical device via transcutaneous inductive energy transfer to a secondary coil associated with the medical device, and adjusting the first position of the energy delivery module comprises adjusting the first position of the primary coil to locate the primary coil proximate to the secondary coil.

3. The method ofclaim 1, further comprising adjusting a size of the headset based on a size of the head.

4. The method ofclaim 1, wherein the fixation mechanism comprises a first fixation mechanism, the method further comprising:

adjusting a third position of a telemetry antenna that is coupled to the headset to locate the telemetry antenna at a fourth position proximate to the medical device; and

adjusting a second fixation mechanism to substantially fix the telemetry antenna at the fourth position proximate the medical device.

5. The method ofclaim 1, further comprising:

adjusting a third position of a telemetry antenna that is coupled to the headset to locate the telemetry antenna at a fourth position proximate to the medical device; and

adjusting the fixation mechanism to substantially fix the telemetry antenna at the fourth position proximate the medical device.

6. The method ofclaim 1, wherein the fixation mechanism comprises a first fixation mechanism, the method further comprising:

adjusting a third position of a stabilizing member that is coupled to the headset; and

adjusting a second fixation mechanism to substantially fix the third position of the stabilizing member.

7. The method ofclaim 1, further comprising molding at least one of a coupling member, a stabilizing member, or a housing member that is coupled to the headset to the head of the patient.

8. The method ofclaim 1, further comprising receiving an indication of alignment of the energy delivery module and the medical device via a recharge control unit.

9. The methodclaim 1, wherein the coupling member is coupled to the headset such that the coupling member is adjustable along at least three axes of motion, and one of the axes of motion comprises a rotational axis.

10. The method ofclaim 1, wherein the coupling member is moldable.

11. The method ofclaim 1, wherein adjusting the fixation mechanism comprises manipulating the fixation mechanism between a first state in which the coupling member is adjustable relative to the headset and a second state in which a third position of the coupling member is substantially fixed relative to the headset.

12. The method ofclaim 1, wherein the fixation mechanism comprises a bolt, and adjusting the fixation mechanism comprises tightening the bolt.

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