Patent Application
20250001186
The present disclosure relates generally to implantable cochlear stimulation (or “ICS”) systems.
ICS systems are used to help the profoundly deaf perceive a sensation of sound by directly exciting the intact auditory nerve with controlled impulses of electrical current. Ambient sound pressure waves are picked up by an externally worn microphone and converted to electrical signals. The electrical signals, in turn, are processed by a sound processor, converted to a pulse sequence having varying pulse widths, rates and/or amplitudes, and transmitted to an implanted receiver circuit of the ICS system. The implanted receiver circuit is connected to an implantable electrode array that has been inserted into the cochlea of the inner ear, and electrical stimulation current is applied to varying electrode combinations to create a perception of sound. The electrode array may, alternatively, be directly inserted into the cochlear nerve without residing in the cochlea. A representative ICS system is disclosed in U.S. Pat. No. 5,824,022, which is entitled “Cochlear Stimulation System Employing Behind-The-Ear Sound processor With Remote Control” and incorporated herein by reference in its entirety. Examples of commercially available ICS sound processors include, but are not limited to, the Harmony™ BTE sound processor, the Naida™ CI Q Series sound processor and the Neptune™ body worn sound processor, which are available from Advanced Bionics.
As alluded to above, some ICS systems include an implantable cochlear stimulator (or “cochlear implant”), a sound processor unit (e.g., a body worn processor or behind-the-ear processor), and a microphone that is part of, or is in communication with, the sound processor unit. The cochlear implant communicates with the sound processor unit and, some ICS systems include a headpiece that is in communication with both the sound processor unit and the cochlear implant. The headpiece communicates with the cochlear implant by way of a transmitter (e.g., an antenna) on the headpiece and a receiver (e.g., an antenna) on the implant. Optimum communication is achieved when the transmitter and the receiver are aligned with one another. To that end, the headpiece and the cochlear implant may include respective positioning magnets that are attracted to one another, and that maintain the position of the headpiece transmitter over the implant receiver. The implant magnet may, for example, be located within a pocket in the cochlear implant housing. The skin and subcutaneous tissue that separates the headpiece magnet and implant magnet is sometimes referred to as the “skin flap,” which is frequently 3 mm to 11 mm thick.
The present inventors have determined that conventional cochlear implants and stimulation systems are susceptible to improvement. For example, the magnet in some conventional cochlear implant is a disk-shaped axially magnetized magnet that has north and south magnetic dipoles which are aligned in the axial direction of the disk. Such magnets are not compatible with magnetic resonance imaging (“MRI”) systems, and may have to be surgically removed from the cochlear the implant prior to the MRI procedure and then surgically replaced thereafter. Other cochlear implants include a diametrically magnetized disk-shaped magnet that is rotatable relative to the remainder of the implant about its central axis, and that has a N-S orientation which is perpendicular to the central axis. The present inventors have determined that diametrically magnetized disk-shaped magnets are less than optimal because a dominant magnetic field, such as the MRI magnetic field, that is misaligned by at least 30° or more from the N-S direction of the magnet may demagnetize the magnet or generate an amount of torque on the magnet that is sufficient to dislodge or reverse the magnet and/or dislocate the associated cochlear implant and/or cause excessive discomfort to the patient.
More recently, cochlear implants with MRI-compatible magnet apparatus have been introduced. The MRI-compatible magnet apparatus have a case defining a central axis, a frame within the case that is rotatable relative to the case about the central axis, and three or more elongate diametrically magnetized magnets that are located in the frame in close proximity to one another and that are rotatable about their respective longitudinal axis relative to the frame. This combination allows the magnets to align with three-dimensional (3D) MRI magnetic fields, regardless of field direction, which results in very low amounts of torque on the magnets. Examples of such MRI-compatible magnet apparatus may be found in U.S. Pat. Nos. 9,919,154, 10,463,849, and 10,532,209. Another proposed magnet apparatus, which includes a single elongate magnet, is described in PCT Pat. Pub. No. 2020/092185 A1.
Although such MRI-compatible magnet apparatus have proven to be a significant advance in the art, the present inventors have determined that they are susceptible to improvement. For example, the field strength of MRI systems continues to increase and the amount of torque associated with placement of a particular MRI-compatible magnet apparatus into a 5 Tesla (5T) MRI magnetic field or a 7 Tesla (7T) MRI magnetic field may be significantly greater than the amount of torque associated with placement of the same MRI-compatible magnet apparatus into a 3 Telsa (3T) MRI magnetic field. The present inventors have also determined that it would be desirable to reduce the amount of magnetic material within a MRI-compatible magnet apparatus, thereby reducing the torque associated with a MRI magnetic field, without a corresponding reduction in the attraction force between the MRI-compatible magnet apparatus and the headpiece magnet, and without a corresponding increase in the size of the headpiece magnet. The present inventors have further determined that it would be desirable to more efficiently employ the magnetic field of the headpiece magnet, thereby further facilitating the use of less magnetic material within the MRI-compatible magnet apparatus.
A method in accordance with at least one of the present inventions may include positioning a headpiece, including an axially magnetized magnet that defines a N-S direction and an antenna, on a portion of a user's head over an implanted cochlear implant including a magnet apparatus. The magnet apparatus may include a case, a frame within the case and rotatable about the central axis of the case, and only two elongate diametrically magnetized magnets that are located in the frame, that each define a longitudinal axis and a N-S direction, that are rotatable about the longitudinal axis relative to the frame, that are attracted to one another with an attraction force F1, and that are separated from one another by a fixed non-zero distance that is perpendicular to at least one of the longitudinal axes. When the distance between the axially magnetized magnet and the elongate diametrically magnetized magnets is 12 mm, there is a magnetic attraction force F2, which greater than the magnetic attraction force F1, between axially magnetized magnet of the positioned headpiece and the elongate diametrically magnetized magnets.
A system in accordance with at least one of the present inventions may include a head wearable external component, including an axially magnetized external magnet, and a cochlear implant having a cochlear lead, an implant antenna, an implant processor and an implant magnet assembly. The implant magnet assembly may include an implant magnet case defining a central axis, a frame within the implant magnet case and rotatable relative to the implant magnet case about the central axis of the implant magnet case, and only two elongate diametrically magnetized implant magnets that are located in the frame, that each define a longitudinal axis and have an individual magnetic dipole moment, that are rotatable about the longitudinal axis relative to the frame, and that are separated from one another by a fixed non-zero distance that is perpendicular to at least one of the longitudinal axes.
A magnet apparatus in accordance with at least one of the present inventions may include a case, a magnet frame within the case and rotatable about the central axis of the case, and only two elongate diametrically magnetized magnets that are located in the frame, that are separated from one another by a fixed non-zero distance, that each define a longitudinal axis and a N-S direction, that are rotatable about the longitudinal axis relative to the frame, and that are attracted to one another with a magnetic attraction force that is less than 3.0 N.
A magnet apparatus in accordance with at least one of the present inventions may include a case, a magnet frame within the case and rotatable about the central axis of the case, and only two elongate diametrically magnetized magnets that are located in the frame, that are separated from one another by a fixed non-zero distance, that each define a longitudinal axis and a N-S direction, that are rotatable about the longitudinal axis relative to the frame, and that define a total magnet volume that is less than about 20% to about 30% of the internal volume of the case.
A magnet apparatus in accordance with at least one of the present inventions may include a case, a magnet frame within the case and rotatable about the central axis of the case, and only two elongate diametrically magnetized magnets that are located in the frame, that are separated from one another by a fixed distance of about 3.8 mm to about 4.2 mm, that each define a longitudinal axis and a N-S direction, and that are rotatable about the longitudinal axis relative to the frame.
A magnet apparatus in accordance with at least one of the present inventions may include a case defining a central axis and an inner surface, a frame, within the case and rotatable about the central axis of the case, including first and second base members with respective curved end surfaces adjacent to the inner surface of the case and first and second bars that extend from the first base member to the second base member, the first and second base members and first and second bars together defining first and second magnet receptacles and an open region located between the first and second bars and, a first elongate diametrically magnetized magnet located in the first magnet receptacle and a second elongate diametrically magnetized magnet located in the second magnet receptacle, wherein there is no magnet located within the open region.
A magnet apparatus in accordance with at least one of the present inventions may include a case defining a central axis and an inner surface, a frame, within the case and rotatable about the central axis of the case, defining an outer perimeter that includes first and second arcuate portions and first and second indentations, and a first elongate diametrically magnetized magnet located in the first indentation and a second elongate diametrically magnetized magnet located in the second indentation.
There are a number of advantages associated with such methods and apparatus. By way of example, but not limitation, the use of only two rotatable elongate diametrically magnetized magnets in the magnet apparatus reduces the amount of magnet material within the magnet apparatus, while the spacing between the elongate diametrically magnetized magnets reduces the magnetic attraction between the two magnets. The reduction in the magnetic attraction between the magnets within the magnet apparatus facilitates the use of an axially magnetized headpiece magnet, which is more magnetically efficient that a diametrically magnetized headpiece magnet due to the orientation of the magnetic field, because the magnets within the magnet apparatus will rotate into alignment with the magnetic field of the axially magnetized headpiece magnet. Accordingly, the present methods and apparatus employ less magnetic material within the magnet apparatus, the elongate diametrically magnetized magnets have less attraction force to one another due to the distance between the magnets, and there is less friction between rotating magnets and the inner surface of the case, thereby reducing the torque associated with placement of the magnet apparatus into a MRI magnetic field. As compared to a magnet apparatus with three or more elongate diametrically magnetized magnets, the present two-magnet apparatus also creates less of an MRI artifact (which may facilitate brains scans) and is less costly to manufacture. MRI artifacts may be further reduced by reducing the amount of frame material by way of the open region and/or frame indentations. The present methods and apparatus also do so without reducing the magnetic attraction between the headpiece and the cochlear implant or increasing the size of headpiece magnet.
The above described and many other features of the present inventions will become apparent as the inventions become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
Detailed descriptions of the exemplary embodiments will be made with reference to the accompanying drawings.
The following is a detailed description of the best presently known modes of carrying out the inventions. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the inventions.
As illustrated for example in
The case 102 in the exemplary magnet apparatus 100 is disk-shaped and defines a central axis A1, which is also the central axis of the frame 108. The frame 108 is rotatable relative to the case 102 about the central axis A1 over 360°. The magnets 110 rotate with the frame 108 about the central axis A1. Each magnet 110 is also rotatable relative to the frame 108 about its own longitudinal axis A2 (also referred to as “axis A2”) over 360°. In the exemplary implementation illustrated in
The exemplary case 102 is not limited to any particular configuration, size or shape. In the illustrated implementation, the case 102 is a two-part structure that includes the base 104 and the cover 106 which are secured to one another in such a manner that a hermetic seal is formed between the cover and the base. Suitable techniques for securing the cover 106 to the base 104 include, for example, seam welding with a laser welder. With respect to materials, the case 102 may be formed from biocompatible paramagnetic metals, such as titanium or titanium alloys, and/or biocompatible non-magnetic plastics such as polyether ether ketone (PEEK), low-density polyethylene (LDPE), high-density polyethylene (HDPE), ultra-high-molecular-weight polyethylene (UHMWPE), polytetrafluoroethylene (PTFE) and polyamide. In particular, exemplary metals include commercially pure titanium (e.g., Grade 2) and the titanium alloy Ti-6Al-4V (Grade 5), while exemplary metal thicknesses may range from 0.20 mm to 0.25 mm. With respect to size and shape, the case 102 may have an overall size and shape similar to that of conventional cochlear implant magnets so that the magnet apparatus 100 can be substituted for a conventional magnet in an otherwise conventional cochlear implant. The case 102 may also have an overall size and shape that is larger than that of conventional cochlear implant magnets in other embodiments. In some implementations, the diameter that may range from 9 mm to 17.4 mm and the thickness may range from 1.5 mm to 4.0 mm. The diameter of the case 102 in the illustrated embodiment is about 12.6 mm and the thickness is about 3.1 mm. As used herein in the context of the case 102, the word “about” means±10%.
The exemplary frame 108 includes a disk 112 and only two receptacles 114. A used herein, the phrase “only two” means “two and no more than two.” The receptacles 114 extend completely through the disk and that are defined by inner walls 116. Suitable materials for the frame 108 (as well as the other frames described herein), which may be formed by machining, metal injection molding or injection molding, include paramagnetic metals, polymers and plastics such as those discussed above in the context of the case 102. Referring more specifically to
The magnets 110 in the exemplary magnet apparatus 100 are elongate diametrically magnetized magnets, and there are only two magnets 110 within the case 102. As noted above, the phrase “only two” is used herein to mean “two and no more than two.” The exemplary magnets 110 are circular in a cross-section that is perpendicular to the longitudinal axis A2 and, in some instances, may have rounded corners. Suitable materials for the magnets 110 include, but are not limited to, neodymium-boron-iron and samarium-cobalt. The frame 108 maintains the maintains the spacing between the magnets 110. As is discussed in greater detail below, the magnetic attraction force F1 between the two spaced magnets 110, which is a function of the distance between the magnets, is such that the magnets will remain substantially aligned with one another in the N-S direction, as shown in
The magnets 110 may be located within tubes 118 formed from low friction material. Suitable materials for the tubes 118 include polymers, such as silicone, PEEK and other plastics, PTFE, and PEEK-PTFE blends, and paramagnet metals. The magnets 110 may be secured to the tubes 118 such that the each tube rotates with the associated magnet about its axis A2, or the magnets may be free to rotate relative to the tubes. The magnet/tube combination is also more mechanically robust than a magnet alone. The magnets 110 may, in place of the tubes 118, be coated with the lubricious materials discussed below.
Friction may be further reduced by coating the inner surfaces of the case 102 and/or the surfaces of the frame 108 with a lubricious layer. The lubricious layer may be in the form of a specific finish of the surface that reduces friction, as compared to an unfinished surface, or may be a coating of a lubricious material such as diamond-like carbon (DLC), titanium nitride (TiN), PTFE, polyethylene glycol (PEG), Parylene, fluorinated ethylene propylene (FEP) and electroless nickel sold under the tradenames Nedox® and Nedox PF™. The DLC coating, for example, may be only 0.5 to 5 microns thick. In those instances where the base 104 and a cover 106 are formed by stamping, the finishing process may occur prior to stamping. Micro-balls, biocompatible oils and lubricating powders may also be added to the interior of the case to reduce friction. In the illustrated implementation, the surfaces of the frame 108 may be coated with a lubricious layer 120 (e.g., DLC), while the inner surfaces of the case 102 do not include a lubricious layer, as shown in
Referring to
Another aspect of the exemplary magnet apparatus 100 is the impact resistance associated with the locations of the elongate diametrically magnetized magnets 110. When the magnet apparatus 100 is subjected to an impact force (e.g., when the user bumps his/her head), the central portion of the case 102 will deflect inwardly. Advantageously, the magnets 110 are offset from the central axis A1 of the case 102 by the distance D1 (
Referring also to
It should be noted here that although the diametrically magnetized magnets 110 are identical to one another, are parallel to one another, and are equidistant from the central axis A1 of the case 102 in the illustrated embodiment, the present magnet apparatus are no so limited. By way of example, but not limitation, the diametrically magnetized magnets 110 may have different lengths and/or may have different diameters and/or may be formed from materials having the same or different strength. Alternatively, or in addition, the diametrically magnetized magnets 110 may be non-parallel, and be different distances from the central axis A1 of the case 102. The configurations of the receptacles 114 would be adjusted to accommodate that of the magnets 110.
Turning to
Another exemplary magnet apparatus is generally represented by reference numeral 100a in
Suitable materials for the frame 108a include those discussed above with reference to the case 102 and frame 108. By way of example, but not limitation, the frame 108a may be formed from a DLC coated metal material. In the illustrated implementation, the frame 108a is formed from molded PEEK and an open region 130 defined between the upper and lower curved flanges 126 and 128. The lack of molded material in the open region 130 prevents distortion of the molded frame 108a as the frame cools during the manufacturing process. Material may be removed from other portions of a molded frame for the same reason. To that end, the exemplary fame 108b illustrated in
The PEEK (or other molded material) may be protected from the heat associated with the welding of the case cover 106 to the base 104 through the use of a titanium ring 132 that is positioned against the inner surface of the case 102. The titanium ring 132 may be omitted when a metal frame 108a is employed.
Another exemplary magnet apparatus (or “magnet assembly”) is generally represented by reference numeral 100c in
Here, however, the exemplary frame 108c includes first and second base members 134c, which have curved end surfaces 136c, and first and second bars 138c that extend from one base member to the other. The base members 134c and bars 138c together define receptacles 114c for the magnets 110c and an open region 140c between the bars 138c. The bars 138c maintain a distance D1 between the magnets, which may be the same as the distance D1 discussed above. The open region 140c does not include any of the frame material and extends from one side of the frame 108c to the other, i.e., completely through the frame from the top side of the frame 108c to the bottom side in the orientation illustrated in
Referring more specifically to
It should also be noted that various aspects of the exemplary frame 108c may be individually incorporated into the frame 108. The exemplary frame 108′ illustrated in
Another exemplary magnet apparatus (or “magnet assembly”) is generally represented by reference numeral 100d in
The exemplary magnet apparatus 100d is also configured to be anchored to bone. The magnet apparatus 100d may be anchored to bone when the associated cochlear implant is initially implanted, or the magnet apparatus 100d may be anchored to bone as part of an in situ replacement of an implant magnet in, for example, the manner described in US Pat. Pub. No. 2019/0046797A1, which is incorporated herein by reference. A bone screw or other anchor may be permanently affixed to the exterior of the case in some instances. In the illustrated embodiment, the magnet apparatus 100d is configured to permit passage of an anchor, such as the illustrated bone screw 90 through the case 102d. The bone screw 90, which includes a threaded shaft 92 (threads not shown) and a flat head 94, may be inserted through the case 102d before or after the case has been placed on or adjacent to bone. The bone screw 90 may then be driven into the bone until the head of the bone screw reaches a corresponding mating surface on the case 102d, thereby anchoring the magnet apparatus 100d to the skull.
The exemplary case 102d and frame 108d are each configured to accommodate the bone screw 90. The case 102d includes a central aperture 148d that extends completely through the case. The central aperture 148d is defined by a tube 150d that extends from top wall 152d of the cover 106d to the bottom wall 154d of the base 104d. In particular, the tube 150d has a frustoconical (or “countersunk”) portion 156d at the top wall 152d and a cylindrical portion 158d that extends from the frustoconical portion to an aperture 160d in the bottom wall 154d. Turning to the frame 108d, the tube 150d passes through the open region 140d and the bars 138d include recesses 162d for the frustoconical portion 158d of the of the tube 150d.
One example of a cochlear implant (or “implantable cochlear stimulator”) including the present magnet apparatus 100 (or 100a) is the cochlear implant 200 illustrated in
Turning to
The exemplary body worn sound processor 300 in the exemplary ICS system 60 includes a housing 302 in which and/or on which various components are supported. Such components may include, but are not limited to, sound processor circuitry 304, a headpiece port 306, an auxiliary device port 308 for an auxiliary device such as a mobile phone or a music player, a control panel 310, one or more microphones 312, and a power supply receptacle 314 for a removable battery or other removable power supply 316 (e.g., rechargeable and disposable batteries or other electrochemical cells). The sound processor circuitry 304 converts electrical signals from the microphone 312 into stimulation data. The exemplary headpiece 400 includes a housing 402 and various components, e.g., a RF connector 404, a microphone 406, an antenna (or other transmitter) 408 and an axially magnetized disk-shaped positioning magnet 410, that are carried by the housing. The headpiece 400 may be connected to the sound processor headpiece port 306 by a cable 412. The external positioning magnet 410 is attracted to the magnet apparatus 100 of the cochlear stimulator 200 (see
In at least some implementations, the cable 412 will be configured for forward telemetry and power signals at 49 MHz and back telemetry signals at 10.7 MHz. It should be noted that, in other implementations, communication between a sound processor and a headpiece and/or auxiliary device may be accomplished through wireless communication techniques. Additionally, given the presence of the microphone(s) 312 on the sound processor 300, the microphone 406 may be also be omitted in some instances.
The functionality of the sound processor 300 and headpiece 400 may also be combined into a single head wearable sound processor that includes all of the external components (e.g., the battery, microphone, sound processor, antenna coil and magnet). Examples of head wearable sound processors are illustrated and described in U.S. Pat. Nos. 8,811,643 and 8,983,102, which are incorporated herein by reference in their entirety. Headpieces and head wearable sound processors are collectively referred to herein as “head wearable external components.”
The present inventions are applicable to systems that include cochlear implants which have already been implanted into the recipient. For example, a similarly sized magnet, or a magnet apparatus with a similarly sized case, may be removed in situ from an implanted cochlear implant (Step 01). In some instances, the magnet or magnet apparatus may be removed from a pocket in the cochlear implant housing. The exemplary magnet apparatus 100 (or 100a or 108c or 108d) described herein may be installed in place of the removed magnet or magnet apparatus (Step 02). In some instances, the magnet apparatus 100 (or 100a or 108c or 108d) may be inserted into the same pocket in the cochlear implant housing from which magnet or magnet apparatus was removed. Suitable removal and installation tools and techniques are illustrated and described in U.S. Pat. No. 10,124,167, which is incorporated herein by reference in its entirety. The headpiece magnet in the associated system may, if necessary, be removed from the headpiece or other head wearable external component and replaced with an axially magnetized magnet.
Although the inventions disclosed herein have been described in terms of the preferred embodiments above, numerous modifications and/or additions to the above-described preferred embodiments would be readily apparent to one skilled in the art. The inventions include any combination of the elements from the various species and embodiments disclosed in the specification that are not already described. It is intended that the scope of the present inventions extend to all such modifications and/or additions and that the scope of the present inventions is limited solely by the claims set forth below.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/046329 | 10/11/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17499813 | Oct 2021 | US |
| Child | 18701199 | US |
