WO2010096573A1

WO2010096573A1 - Implant system for controlling airway passage

Info

Publication number: WO2010096573A1
Application number: PCT/US2010/024604
Authority: WO
Inventors: Koray Sahin; Christopher Bagley; Cassidy Domingo
Original assignee: Pavad Medical, Inc.
Priority date: 2009-02-18
Filing date: 2010-02-18
Publication date: 2010-08-26

Abstract

A tongue implant system, method, and apparatus are disclosed. The tongue implant system includes an implant device and a non-implanted device. The implant device can be formed of a non-magnetic material that is compatible with diagnostics such as magnetic resonance imaging (MRI) and can include a rotor element configured to rotate under the influence of an external magnetic field. The non-implanted device can include a stator element and drive circuitry for generating the external magnetic field. The non-implanted device can receive a user command and can vary the external magnetic field based on the command. When activated by the magnetic field, the implant device can interact with the tongue to restrict its movement or release the tongue from a restricted state.

Description

IMPLANT SYSTEM FOR CONTROLLING AIRWAY PASSAGE

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/153,455 (atty. docket no. 026705-001500), filed February 18, 2009, the entirety of which is incorporated by reference herein.

BACKGROUND

[0002] Snoring is very common among mammals including humans. Snoring is a noise produced while breathing during sleep due to the vibration of the soft palate and uvula. Not all snoring is bad, except it bothers the bed partner or others near the person who is snoring. If the snoring gets worse over time and goes untreated, it could lead to apnea.

[0003] Those with apnea stop breathing in their sleep, often hundreds of times during the night. Usually apnea occurs when the throat muscles and tongue relax during sleep and partially block the opening of the airway. When the muscles of the soft palate at the base of the tongue and the uvula relax and sag, the airway becomes blocked, making breathing labored and noisy and even stopping it altogether. Sleep apnea also can occur in obese people when an excess amount of tissue in the airway causes it to be narrowed.

[0004] In a given night, the number of involuntary breathing pauses or "apneic events" may be as high as 20 to 60 or more per hour. These breathing pauses are almost always accompanied by snoring between apnea episodes. Sleep apnea can also be characterized by choking sensations.

[0005] Sleep apnea is diagnosed and treated by primary care physicians, pulmonologists, neurologists, or other physicians with specialty training in sleep disorders. Diagnosis of sleep apnea is not simple because there can be many different reasons for disturbed sleep.

[0006] The specific therapy for sleep apnea is tailored to the individual patient based on medical history, physical examination, and the results of polysomnography. Medications are generally not effective in the treatment of sleep apnea. Oxygen is sometimes used in patients with central apnea caused by heart failure. It is not used to treat obstructive sleep apnea. [0007] Continuous positive airway pressure (CPAP) is the most common treatment for sleep apnea. In this procedure, the patient wears a mask over the nose or mouth during sleep, and pressure from an air blower forces air through the air passages. The air pressure is adjusted so that it is just enough to prevent the throat from collapsing during sleep. The pressure is constant and continuous. CPAP prevents airway closure while in use, but apnea episodes return when CPAP is stopped or it is used improperly. Many variations of CPAP devices are available and all have the same side effects such as nasal irritation and drying, facial skin irritation, abdominal bloating, mask leaks, sore eyes, and headaches. Some versions of CPAP devices vary the pressure to coincide with the person's breathing pattern, and other CPAP devices start with low pressure, slowly increasing it to allow the person to fall asleep before the full prescribed pressure is applied.

[0008] Dental appliances that reposition the lower jaw and the tongue have been helpful to some patients with mild to moderate sleep apnea or who snore but do not have apnea. A dentist or orthodontist is often the one to fit the patient with such a device.

[0009] Some patients with sleep apnea may need surgery. Although several surgical procedures are used to increase the size of the airway, none of them is completely successful or without risks. More than one procedure may need to be tried before the patient realizes any benefits. Some of the more common procedures include removal of adenoids and tonsils (especially in children), nasal polyps or other growths, or other tissue in the airway and correction of structural deformities. Younger patients seem to benefit from these surgical procedures more than older patients.

[0010] Uvulopalatopharyngoplasty (UPPP) is a procedure used to remove excess tissue at the back of the throat (tonsils, uvula, and part of the soft palate). The success of this technique may range from 30 to 60 percent. The long-term side effects and benefits are not known, and it is difficult to predict which patients will do well with this procedure.

[0011] Laser- assisted uvulopalatoplasty (LAUP) is done to eliminate snoring but has not been shown to be effective in treating sleep apnea. This procedure involves using a laser device to eliminate tissue in the back of the throat. Like UPPP, LAUP may decrease or eliminate snoring but not eliminate sleep apnea itself. Elimination of snoring, the primary symptom of sleep apnea, without influencing the condition may carry the risk of delaying the diagnosis and possible treatment of sleep apnea in patients who elect to have LAUP. To identify possible underlying sleep apnea, sleep studies are usually required before LAUP is performed.

[0012] Somnoplasty is a procedure that uses RF to reduce the size of some airway structures such as the uvula and the back of the tongue. This technique helps in reducing snoring and is being investigated as a treatment for apnea.

[0013] Tracheostomy is used in persons with severe, life-threatening sleep apnea. In this procedure, a small hole is made in the windpipe and a tube is inserted into the opening. This tube stays closed during waking hours and the person breathes and speaks normally. It is opened for sleep so that air flows directly into the lungs, bypassing any upper airway obstruction. Although this procedure is highly effective, it is an extreme measure that is rarely used.

[0014] Patients in whom sleep apnea is due to deformities of the lower jaw may benefit from surgical reconstruction. Surgical procedures to treat obesity are sometimes recommended for sleep apnea patients who are morbidly obese. Behavioral changes are an important part of the treatment program, and in mild cases behavioral therapy may be all that is needed. Overweight persons can benefit from losing weight. Even a 10 percent weight loss can reduce the number of apneic events for most patients. Individuals with apnea should avoid the use of alcohol and sleeping pills, which make the airway more likely to collapse during sleep and prolong the apneic periods. In some patients with mild sleep apnea, breathing pauses occur only when they sleep on their backs. In such cases, using pillows and other devices that help them sleep in a side position may be helpful.

[0015] Recently, Restore Medical, Inc., Saint Paul, MN has developed a new treatment for snoring and apnea, called the Pillar technique. Pillar System involves a procedure where 3 or more small polyester rod devices are placed in the patient's soft palate. The Pillar System stiffens the palate, reduces vibration of the tissue, and prevents the possible airway collapse. Stiff implants in the soft palate, however, could hinder patient's normal functions like speech, ability to swallow, coughing and sneezing. Protrusion of the implant into the airway is another long-term concern.

[0016] As the current treatments for snoring and/or apnea are not effective and have side- effects, there is a need for additional treatment options. BRIEF SUMMARY OF EMBODIMENTS

[0017] In one embodiment of the present invention, a device for stabilizing the tongue is disclosed. The device includes a housing having a first end configured to secure the housing to a patient's mandible. A transducer is disposed within the housing and rotates under the influence of a magnetic field from outside of the patient's body. An anchor is coupled to the transducer and can securely engage with the patient's tongue for controlling a movement of the tongue within the patient's mouth. The housing, transducer, and anchor can be comprised of non-magnetic materials such that the implant is fully compatible with Magnetic Resonance Imaging (MRI) and other diagnostics. The transducer can be surrounded by a biocompatible insulating material for preventing tissue in-growth. In one embodiment, the transducer includes a squirrel-cage rotor having a plurality of copper conductive members.

[0018] In another embodiment, a device for controlling an implant is disclosed. The implant includes a rotor element that is disposed within a patient's body. The device includes a housing adapted to engage with an outside of the patient's body. A stator element is disposed within the housing. The stator element comprises a plurality of poles, and each pole has an associated winding. A driver varies a current flow within the windings so as to produce a rotating magnetic field. A processor is coupled to the driver and controls its operation. The processor is configured to detect the presence of the rotor element based on a level of the current flow in the windings. In some embodiments, housing has a contoured portion that surrounds at least a front and side surface of the implant when the housing is engaged with the patient's body. The stator element can have four poles and each pole can have a chamfered end feature. The driver can be a two-phase driver.

[0019] In one embodiment, a system for stabilizing the tongue is disclosed. The system includes an implanted device for controlling movement of a patient's tongue and a non- implanted device for operating the implant. The implanted device can include a nonmagnetic rotor element that is configured to interact with the tongue in response to a rotating magnetic field. The non-implanted device can include a stator element that supports the rotating magnetic field. The non-implanted device can generate a first rotating magnetic field for restricting tongue movement and a second rotating magnetic field for releasing the tongue based on a user input.

[0020] In one embodiment, a method for stabilizing the tongue of a patient is disclosed. One of the implanted devices disclosed herein, which is moveably connected to the tongue, may be actuated using one of the non-implanted devices disclosed herein, to place the tongue in a stabilized position from an initial non-stabilized position.

BRIEF DESCRIPTION OF THE DRAWINGS [0021] Fig. 1 is a simplified diagram of a tongue implant system.

[0022] Fig. IA is an explanatory diagram illustrating aspects of a tongue implant system.

[0023] Fig. 2 illustrates an embodiment of a tongue implant device.

[0024] Fig. 3 illustrates an embodiment of a tongue implant device.

[0025] Figs. 4A-4B illustrate different embodiments of an implanted rotor.

[0026] Fig. 5 illustrates a device for controlling a tongue implant.

[0027] Fig. 6 is a functional block diagram of an embodiment of an implant control circuit.

[0028] Fig. 7 is a magnetic flux diagram showing aspects of an external magnetic field.

[0029] Figs. 8A-8F illustrate different embodiments of a stator.

[0030] Fig. 9 is an exemplary flowchart of steps for operating a tongue implant.

[0031] The features, objects, and advantages of embodiments of the disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like elements bear like reference numerals.

DETAILED DESCRIPTION OF EMBODIMENTS

[0032] A tongue implant system, method, and apparatus are disclosed. The tongue implant system includes an implant device and a non-implanted device. The implant device can be formed of a non-magnetic material that is compatible with diagnostics such as magnetic resonance imaging (MRI) and can include a rotor element configured to rotate under the influence of an external magnetic field. The non-implanted device can include a stator element and drive circuitry for generating the external magnetic field. The non-implanted device can receive a user command and can vary the external magnetic field based on the command. When activated by the magnetic field, the implant device can interact with the tongue to restrict its movement or release the tongue from a restricted state. Applicants' co- pending application serial no. 12/250,398, filed on October 13, 2008 (atty. docket no. 026705-001400US), discloses additional details relating to embodiments of the present invention and is expressly incorporated herein by reference for all purposes.

[0033] Fig. 1 is a simplified diagram of a tongue implant system 100 according to one embodiment of the present invention. In the diagram, element 110 refers to the tongue and element 120 is the mandibula. As shown, implant system 100 includes an implant 130 that is inserted into a patient's body and a non-implanted portion 140 that is external to the patient. The non-implanted portion 140 can control operation of the implant 130 to avoid obstruction of the airway passage by interacting with tongue 110.

[0034] In some embodiments, implant 130 includes an anchor portion, an actuator, and a connecting member. The anchor portion is used to secure implant 130 to the mandibula 120 and can include a titanium bracket and titanium bone screws. The actuator can be a transducer which converts a rotating external magnetic field into a rotational motion. For example, the actuator can include a conductor configured to rotate under the influence of the external magnetic field. The connecting member is disposed between the actuator and the tongue so that, depending upon its direction, rotation of the actuator can interact with the tongue.

[0035] The connecting member can include mechanical means such as a shaft or screw arrangement which translates the rotation of the actuator into a linear motion. In some embodiments, the connecting member includes a flexible portion or a fiber that is securely attached to the base of the tongue at one end and to the shaft or screw at the other end. Rotation of the actuator is thus translated into a linear displacement of the connecting member which interacts with the tongue to produce the desired action.

[0036] Non-implanted portion 140 is configured to control operation of the implant 130. In some embodiments, non-implanted portion 140 (also "controller") includes a housing that is adapted to interface with a patient's body at or near where the implant 130 is located. As shown, the controller 140 has a contoured portion which receives the patient's chin. The contoured portion enables the controller to partially surround the implant 130 so that it faces the implant on several sides. For example, when engaged with the patient, controller 140 can form a roughly hemispherical coverage area with respect to the implant.

[0037] Controller 140 can be configured to produce magnetic fields for operating the implant. In one embodiment, controller 140 includes a stator element. The stator can have a ferromagnetic core. The ferromagnetic core can be formed from a single piece of material. In some embodiments, the ferromagnetic core is formed from a plurality of laminations. The stator element can have multiple poles each of which is adapted to receive a conductive winding. The number of poles and windings can vary. In a preferred embodiment, the stator element has four poles and two conductive windings arranged so that each winding spans two different poles.

[0038] Fig. IA is a conceptual diagram illustrating aspects of implant system 100. In this diagram, the interaction of a stator 150 and a rotor 170 is shown. The stator 150 can be part of controller 140 and is shown in position external to the patient's body near to the implant. The rotor 170 can be part of the actuator portion of implant 130 and is located beneath the skin. Other aspects of the implant 130 and non-implanted portion 140 are omitted for clarity in describing the interaction between stator 150 and rotor 170.

[0039] Stator 150 includes windings 155, 160 and core 165. In operation, a driver supplies an alternating current to each winding and controls a phase relationship between the current flows. The alternating current in each winding creates a changing magnetic field which can pass through the patient's body in the vicinity of the rotor 170. When taken together, the alternating currents produce a magnetic field that shifts or rotates in relation to the stator 150. The direction of the rotating field can be changed by controlling the current flows.

[0040] Rotor 170 moves under the influence of the changing magnetic field. As shown, rotor 170 can be a squirrel-cage rotor in which a plurality of elongated conducting members are joined at each end by a ring. In some embodiments, rotor 170 is a hollow cylinder that has either a solid surface (e.g., a tube) or a surface with one or more openings. Many variations of rotor 170 are possible within the scope of the present invention.

[0041] Preferably, rotor 170 is formed of a non-magnetic material such as copper. Other suitable, non-magnetic materials can include gold and silver. In some embodiments, implant 130 is constructed entirely of non-magnetic materials to avoid interface with magnetic resonance imaging (MRI) and other diagnostics. The magnetic field from stator 150 induces a current flow in the horizontal conductors of rotor 170. Interaction between the induced current and the rotating magnetic field causes rotor 170 to spin or turn about its axis. Implant 130 thus converts the external magnetic field into mechanical motion that is used to interact with the tongue.

[0042] Controller 140 can include a user-interface for controlling operation of the implant system 100. For example, prior to sleeping, a patient may choose to restrict movement of the tongue in order to avoid closure of the airway passage. Upon waking, or when treatment is no longer desired, the user can activate implant 130 and release the tongue for unrestricted movement. In one embodiment, controller 140 supports at least SET and RELEASE commands for changing the state of implant 130. In some embodiments, status indicators are also provided and can indicate, for example, when the controller 140 is properly positioned for operating the implant 130.

[0043] Fig. 2 is a simplified schematic drawing of a tongue implant device 200 in accordance with one embodiment of the present invention. As shown, the implant 200 can include an anchor portion 205 for securing the implant to the mandibula; a control portion 215 for controlling the flexible portion 225; a flexible portion 225 and an anchor 235 for securing the implant to the base of the tongue. Control portion 215 houses an actuator 245 which, as shown, can be a squirrel-cage rotor. In some embodiments, rotor 245 can be a conductive cylinder, and other rotor configurations can also be used.

[0044] Rotor 245 can be secured for rotation within housing 255 using a guide members 240 and a spindle 260. The guides 240 serve to stabilize the rotor 245 and to maintain its position relative to the walls of housing 255. Spindle 260, on the other hand, connects rotor 245 to the anchoring portion 205 of housing 255 and provides an axis of rotation about which the rotor 245 can spin freely. Housing 255 can include an acrylic or other non-conductive material that resists tissue in-growth. As shown, housing 255 can include tapped holes 270 for anchoring it with biocompatible screws to the mandibula.

[0045] Rotor 245 is also shown coupled to a shaft 275 for controlling displacement of a connecting member 280. The shaft 275 can include a threaded portion which engages with the connecting member 280 such that rotation of the shaft displaces the connecting member and produces a corresponding movement of the anchor portion 235 which can be securely attached to the patient's tongue. The connecting member 280 can include a tough but flexible material such as a Kevlar fiber.

[0046] The flexible portion 225 provides for three-dimensional flexibility of the implant. When the implant 200 is actuated by an external magnetic field, movement of the shaft 275 exerts a pulling action on the connecting member 280 which stiffens the flexible portion 225 along its central longitudinal axis to hold the tongue in position so as not to block the airway. When released, the flexible portion 225 again provides for three-dimensional flexibility of the tongue, so as to enable the patient to have adequate tongue movement during speaking and swallowing.

[0047] The flexible portion 225 can include a flexible spring, bellows, etched stent or a combination of the three as the mechanism for supporting the tongue. Flexible portion 225 can be coated with an HA coating for preventing tissue in-growth. An important functionality of this mechanism is to permit flexible movement of the tongue in all degrees of freedom. When in a restricted state, the implant can tighten the tongue and stabilize it thereby limiting its multiple degrees of freedom. Full movement of the tongue can be restored in a released state. In operation, the implant 200 changes state in response to the external magnetic field. When the external field rotates in one direction, the implant 200 is activated and restricts movement of the tongue. Similarly, when the external field rotates in the opposite direction, the tongue is released and full movement is restored.

[0048] The anchoring mechanism 235 can include two concentric polyester discs 285A- 285B with one 285A connected with the tongue stabilizing mechanism with suture holes around its circumference. The second disc 285B can also have suture holes 290 around its circumference which are concentric with the holes in the first disc. Both discs can be connected by one or more polyester rods with holes 295 for tissue in-growth. The disc further away from the middle flexible portion can be surgically inserted at the base of the tongue at a depth such that the second disc is in contact with the base of the tongue. The surgically implanted disc 285B can also have one or more polyester rods with polyester beads 297 to facilitate good tissue in-growth and hence good anchoring.

[0049] Fig. 3 is a simplified schematic diagram showing details of a tongue implant device 300 according to another embodiment of the present invention. Implant device 300 is similar to the tongue implant of Fig. 2 and includes an anchor 235 for interacting with the tongue in response to movement of the rotor 245. In the presently described embodiment, rotor 245 is fixedly attached to threaded shaft 275. Shaft 275 is received by a threaded portion of base 320 which permits its vertical displacement.

[0050] Movement of rotor 245 causes the rotor-shaft assembly to travel vertically in relation to the base 320. As the shaft 275 descends into the base, a pulling force is exerted on the connecting member 310 which restricts movement of the tongue. Similarly, when rotating in the opposite direction, shaft 275 moves away from base 320 and releases tension on the connecting member 310. This, in turn, frees the tongue for normal movement. The threaded base 320 maintains the shaft-rotor assembly in its contracted or released state when movement of the rotor 245 ceases.

[0051] Figs. 4A-4B show different embodiments of rotor 245 according to the present invention. Fig. 4A is an end view of an exemplary rotor. As shown, conducting members are arranged into a plurality of groups. This configuration avoids the continuous end rings of the squirrel-cage design and can reduce the susceptibility of the rotor to stray magnetic fields. Fig. 4B is a perspective view of another exemplary rotor. As shown, conducting members are joined at each end and an overlapping coil is formed. As with Fig. 4 A, the possible effect of magnetic fields from unintended sources can be reduced.

[0052] Fig. 5 is a diagram of a non-implanted device 500 for operating a tongue implant according to embodiments of the present invention. The non-implanted device 500 includes a housing 510 having a contoured area 520 for interfacing with a patient's body. As illustrated, a stator element 530 is disposed within the housing near the contoured area. In some embodiments, the stator 530 has a plurality of poles each with a chamfered end feature. For example, the chamfered end features can have a reduce cross-sectional area that tapers to the interior portion of the stator 530. The taper of the stator-poles can create a recessed area for receiving the patient's chin. When engaged with the patient, the poles are exposed to different parts of the implant which can facilitate effective coupling of the stator' s magnetic field and the conducting members of an implanted rotor.

[0053] Non-implanted device 500 can also include user interface elements. For example, buttons 540 can be included for controlling operation of the implant. Status indicators such as light-emitting diodes can also be included. In one embodiment, buttons 540 correspond to a SET and RELEASE command for changing the state of the implant. One or more status indicators can be included to aid in aligning the non-implanted device 500 with the implant and for signaling a low-battery condition, etc.

[0054] Fig. 6 is a functional block diagram of a tongue implant control circuit 600 such as can be used with non-implanted device 500. As shown, control circuit 600 includes a processor 610, a drive circuit 620, and a user interface 630. Processor 610 can be a microprocessor, microcontroller, field programmable gate array (FPGA), application specification integrated circuit (ASIC), or the similar device. Processor 610 is configured to receive input/output signals from the user interface 630 and to control the operation of the drive circuit 620. [0055] Drive circuit 620 can be coupled to the stator element (e.g, stator 150, stator 530, etc.) for controlling current flows in its windings. For example, drive circuit 620 can be a two-phase driver which delivers current to a 0° phase winding and a 90° phase winding for generating a rotating magnetic field. The present embodiment is not limited to a two-phase driver, but may include any number of windings and alternating currents arranged so as to create a magnetic field having a desired intensity and other properties.

[0056] In operation, processor 610 receives a command for controlling the implant from user interface 630. For example, the command can be a SET command for restricting movement of the tongue, a RELEASE command for restoring full tongue movement or some other command. Based on the command, processor 610 causes drive circuit 620 to energize the stator windings and to thereby create a rotating magnetic field. The direction in which the field rotates corresponds to the command received. For example, the drive circuit 620 can set up current flows to create a clockwise magnetic field or a counter-clockwise magnetic field as directed by processor 610.

[0057] Processor 610 can also perform safety and positioning functions. In some embodiments, processor 610 monitors the level of current flowing in the stator windings and causes drive circuit 620 to reduce the current or to deenergize the stator if the current exceeds a predetermined level. Also, processor 610 can detect the presence of the implant based on stator currents. For example, processor 610 can detect a drop in current flow associated with magnetic coupling to the implant. In some embodiments, processor 610 signals the proximity of the implant by generating audible tones or flashing LEDs at the user interface 630. By varying a duration of the tones or a flash-rate, a user can guide in proper positioning and alignment of the non-implanted device.

[0058] Fig. 7 is a conceptual diagram showing aspects of the magnetic field 700 created by a non-implanted device according to embodiments of the present invention. In the diagram, core element 710 approximates the stator of the non-implanted device. When current flows in the stator windings, north and south magnetic poles are created in the stator core. The magnetic poles, in turn, are linked by flux lines which can span the air gap between physical poles of the stator core.

[0059] Portions of the magnetic flux extend out from the stator core and magnetically couple with the conductors of the implanted rotor. When the magnetic fields linking opposing poles of the stator rotate, a torque is exerted on the rotor. Assuming a winding fill ratio of approximately 63%, analysis has shown that a four-pole stator according to embodiments of the present invention can generate a magnetic field of sufficient intensity for operating an in- vivo tongue implant device. For example, in various embodiments, a field intensity greater than 0.2T can be generated at a distance of approximately 10 mm from the stator. Analysis indicates that this field intensity can generate a torque of at least 1.5μ N-M and is believed to be sufficient for displacing the tongue.

[0060] Figs. 8A-8F illustrate different stator designs for use with embodiments of the present invention. The various stators can be formed of a ferromagnetic material. In some embodiments, the stators include a plurality of laminations which can, for example, reduce the effect of eddy currents in the core structure.

[0061] Fig. 8A is a four pole stator in a substantially flat rectangular configuration. The stator can be sized to approximately 80 mm on each side and can have a thickness of approximately 10 mm. As illustrated, each pole is uniformly spaced and extends approximately 15 mm into the interior area. In a preferred embodiment, each pole includes a chamfered end feature for receiving a patient's chin. For example, the chamfered poles can slope inward to form a bowl for placement of the chin.

[0062] Fig. 8B is an end-view of a cylindrical stator. As shown, windings about the poles extend the length of the stator and each is pole is joined to a central circular support element. Fig. 8C is a cross-shaped stator which can be substantially flat. Windings cover opposing legs of the cross. Fig. 8D is a modified cross-shape with legs that extend out from the central axis. As with the chamfered end features, the legs can be arranged so as to accommodate placement of the chin. Figs. 8E-8F are top views of alterative stator designs. These stators are designed to facilitate patient-positioning while maintaining a substantially flat external surface.

[0063] Fig. 9 is a flowchart illustrating steps for operating a tongue implant. These steps can be executed by processor (e.g., processor 610) or other control circuitry used with a non- implanted device such as described herein. At block 910, a command for operating the implant is received. The command can be a user command for restricting the tongue, releasing the tongue, or it can be some other command relating to the implant.

[0064] In response to the user command, at block 920, the non-implanted portion determines a current flow in the stator windings. The stator is external to the patient and current flow in the stator windings is controlled so as to produce a rotating magnetic field. The direction of rotation can be determined according to the user command. For example, clockwise rotation may be used to restrict the tongue and counter-clockwise rotation may be used to release the tongue depending upon the mechanical arrangement of the implanted rotor.

[0065] In some embodiments, the amount of current delivered to the stator windings is determined so as to create a magnetic field having a predetermined intensity when measured at a distance separating the non-implanted portion from the implant device. For example, the current flow may be determined so that the intensity of the magnetic field is at least 0.16 T at a typical separation distance of 10 mm.

[0066] At block 930, the stator current and temperature are monitored. If, at any time, unsafe levels of current or temperature are detected, the stator windings can be immediately de-energized or the current level can be reduced and a user of the device can be notified of the condition.

[0067] When the non-implanted device is engaged with the patient, the magnetic field couples with the implanted rotor and stator current changes. This change can vary with rotational speed and the alignment of stator and rotor elements. For example, when the non- implanted portion is first activated, stator current increases. As the rotor spins up and rotational speed stabilizes, stator current may decrease to a steady operating level.

[0068] At block 940, the non-implanted portion detects the level of stator current flow and, at block 950, an alignment indicator is provided. For example, the non-implanted portion can measure the increase in stator current and/or the steady operating level, and compare it with a threshold value (or collection of values) representative of a proper alignment between the stator rotor elements. Based on the comparison, the alignment indicator can signal an insufficient coupling and alert the user to adjust the position of the non-implanted portion accordingly. When the implant operation is completed, at block 960, the stator windings are de-energized and the process completes.

[0069] As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. For example, embodiments of the present invention can include an MRI compatible motor for use in a variety of medical applications. In one embodiment, the implanted rotor and non- implanted control device can control operation of a pump or similar device. Other embodiments of the present invention can be used to move body tissue other than the tongue (e.g., a lap-band type device). Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A device for stabilizing the tongue, comprising: a housing having a first end configured to secure the housing to a patient's mandible; a transducer disposed within the housing and configured to rotate under the influence of a magnetic field from outside of the patient's body; and an anchor coupled to the transducer and configured to securely engage with the patient's tongue for controlling a movement of the tongue within the patient's mouth.

2. The device of claim 1, wherein the transducer comprises a non- magnetic material.

3. The device of claim 2, wherein the non-magnetic material is selected from the group consisting of copper, silver, and gold.

4. The device of claim 2, further comprising: a shaft coupled to the transducer, the shaft comprising a threaded portion; a connecting member coupled to the threaded portion and to the anchor, wherein the shaft is configured to produce a linear displacement of the connecting member when the transducer rotates.

5. The device of claim 2, wherein the transducer comprises a squirrel- cage rotor.

6. The device of claim 5, wherein the squirrel-cage rotor is encased in a biocompatible insulating material.

7. The device of claim 1, further comprising: a connecting member coupling the transducer to the anchor; and a flexible portion disposed between the housing and the anchor to form a seal around the connecting member.

8. A device for controlling an implant, wherein the implant comprises a rotor element disposed within a patient's body, the device comprising: a housing adapted to engage with an outside of the patient's body; a stator element disposed within the housing, the stator element comprising a plurality of poles, each pole having a winding associated therewith; a driver configured to vary a current flow within the windings so as to produce a rotating magnetic field; and a processor coupled to the driver for controlling its operation, the processor configured to detect the presence of the rotor element based on a level of the current flow in the windings.

9. The device of claim 8, wherein the stator element comprises a cross- shaped member having four poles and two windings.

10. The device of claim 8, wherein the stator element comprises a plurality of ferromagnetic laminations.

11. The device of claim 8, wherein the housing comprises a contoured portion adapted to surround at least a front and side surface of the implant when the housing is engaged with the patient's body.

12. The device of claim 11, wherein the stator element is disposed in relation to the contoured portion so that opposing poles of the stator element face distinct surfaces of the implant.

13. The device of claim 8, wherein the poles have a chamfered end feature.

14. The device of claim 8, wherein the stator element is configured to project the rotating magnetic field in an axial direction toward the implant when the housing is engaged with the patient's body.

15. The device of claim 8, wherein the processor is configured to disable operation of the driver when the current flow in the windings exceeds a predetermined level.

16. A system for stabilizing the tongue, comprising: an implanted device for controlling movement of a patient's tongue, the device comprising a non-magnetic rotor element configured to interact with the tongue in response to a rotating magnetic field; and a non-implanted device comprising a stator element configured to support the rotating magnetic field, wherein the non-implanted device generates a first rotating magnetic field for interacting with the tongue and a second rotating magnetic field for releasing the tongue based on a user input.

17. A method for stabilizing the tongue of a patient, the method comprising: actuating the device of claim 1, which is moveably connected to the tongue, using the device of claim 8, to place the tongue into a stabilized position from an initial non- stabilized position, or actuating the implanted device of claim 16, which is moveably connected to the tongue, using the non-implanted device of claim 16, to place the tongue in a stabilized position from an initial non-stabilized position.