U.S. patent application number 16/796058 was filed with the patent office on 2020-08-20 for implant magnet system.
The applicant listed for this patent is Peter Leigh Gibson. Invention is credited to Peter Gibson, Charles Roger Aaron Leigh, Frank Risi, David Walker.
Application Number | 20200261716 16/796058 |
Document ID | 20200261716 / US20200261716 |
Family ID | 1000004806944 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200261716 |
Kind Code |
A1 |
Gibson; Peter ; et
al. |
August 20, 2020 |
IMPLANT MAGNET SYSTEM
Abstract
A magnetic alignment system that can form part of a cochlear
implant system. The magnetic alignment system prevents substantial
movement of a magnet of an implanted component during an MRI
procedure or allows for easy removal of the magnet to facilitate
the MRI procedure.
Inventors: |
Gibson; Peter; (South
Coogee, AU) ; Leigh; Charles Roger Aaron; (North
Epping, AU) ; Risi; Frank; (Newtown, AU) ;
Walker; David; (Lane Cove, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gibson; Peter
Leigh; Charles Roger Aaron
Risi; Frank
Walker; David |
South Coogee
North Epping
Newtown
Lane Cove |
|
AU
AU
AU
AU |
|
|
Family ID: |
1000004806944 |
Appl. No.: |
16/796058 |
Filed: |
February 20, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16046635 |
Jul 26, 2018 |
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16796058 |
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15010627 |
Jan 29, 2016 |
10058702 |
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16046635 |
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14866156 |
Sep 25, 2015 |
10232171 |
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15010627 |
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13596912 |
Aug 28, 2012 |
9144676 |
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14866156 |
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11857397 |
Sep 18, 2007 |
8255058 |
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13596912 |
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10820444 |
Apr 8, 2004 |
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11857397 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/375 20130101;
A61N 1/08 20130101; A61N 1/3787 20130101 |
International
Class: |
A61N 1/08 20060101
A61N001/08; A61N 1/378 20060101 A61N001/378; A61N 1/375 20060101
A61N001/375 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2003 |
AU |
2003901696 |
Claims
1-20. (canceled)
21. An implantable medical device, comprising: a first implantable
component including a receiver antenna; and a second implantable
component including a functional electronics device, wherein the
first implantable component is removable connected to the second
implantable component such that the receiver antenna is in
breakable electrical connection with the functional electronic
device.
22. The implantable medical device of claim 21, wherein: the
implantable medical device includes a pin and socket arrangement
that establishes the breakable electrical connection.
23. The implantable medical device of claim 21, wherein: the
implantable medical device is a hearing prosthesis; and the
functional electronics device is a device configured to generate a
stimulation signal that stimulates tissue of a recipient to evoke a
hearing percept.
24. The implantable medical device of claim 21, wherein: the
medical device is configured such that when the connection is
present, the there is no ingress of body fluids into the first
implantable component or the second implantable component when the
implantable medical device is implanted in a recipient.
25. The implantable medical device of claim 21, wherein: the
medical device includes clips that hold the first component to the
second component in the removable manner.
26. The implantable medical device of claim 21, wherein: the
medical device includes a male-female coupling that holds the first
implantable component to the second implantable component in the
removable manner.
27. The implantable medical device of claim 21, wherein the first
component comprises: a radio frequency coil; and a magnet.
28. The implantable medical device of claim 21, wherein: the first
component and the second component define a smooth upper surface
and a smooth lower surface without substantial discontinuities at a
junction between the respective components.
29. The implantable medical device of claim 21, wherein: the
medical device includes a connector that comprises a mechanical
locking mechanism that secures first component to the second
component in a manner that presents tactile feedback when the first
component is connected to the second component.
30. The implantable medical device of claim 21, wherein the first
component comprises: a radio frequency coil; and a magnet, wherein
the entire magnet is contained within a space bounded by an inner
perimeter of the coil.
31. An implantable medical device, comprising: a first implantable
component including a first electronics apparatus supported by a
first chassis; and a second implantable component including a
second electronics apparatus supported by a second chassis, wherein
at least one of the first or second chassis forms a coupling that
releasably mechanically holds the first implantable component to
the second implantable component.
32. The implantable medical device of claim 31, wherein: the first
implantable component includes a device configured to generate a
stimulation signal that stimulates tissue of a recipient to evoke a
hearing percept; and the second implantable component includes an
antenna, wherein when the first implantable component is held to
the second implantable component by the coupling, the antenna is in
electrical communication with the device configured to generate the
stimulation signal.
33. The implantable medical device of claim 31, wherein: the first
chassis forms a first portion of the coupling.
34. The implantable medical device of claim 31, wherein: the first
chassis and the second chassis collectively form the coupling.
35. The implantable medical device of claim 21, wherein: the first
component includes one of a male connector apparatus or a female
connector apparatus and the second component includes the other of
the male connector apparatus or the female connector apparatus.
36. The implantable medical device of claim 21, wherein: the
coupling is a snap coupling.
37. The implantable medical device of claim 21, wherein the first
component comprises: a radio frequency coil; and a magnet, wherein
the magnet and the coil are coaxially aligned.
38. A method, comprising: accessing an implanted device of a
medical device implanted in a recipient through an incision in skin
of the recipient, the implanted device including a first component
removably coupled to a second component, the second component being
attached to tissue of the recipient in a manner more substantially
than the first component; uncoupling the first component from the
second component without removing the second component from the
recipient; and removing the first component from the recipient
without removing the second component from the recipient.
39. The method of claim 38, wherein: the first component is an
antenna of the medical device that is in electrical communication
with the second component when the first component is coupled to
the second component.
40. The method of claim 38, further comprising: exposing the
recipient to an MRI magnetic field while the first component is
removed from the recipient; and replacing the first component after
the exposure to the MRI magnetic field is completed.
41. The method of claim 38, further comprising: exposing the
recipient to an MRI magnetic field while the first component is
removed from the recipient; and replacing the first component,
wherein the first component is an antenna of the medical device
that is in electrical communication with the second component when
the first component is coupled to the second component.
42. The method of claim 38, wherein: the action of uncoupling the
first component from the second component without removing the
second component from the recipient is executed by undoing a snap
coupling that holds the first component to the second
component.
43. The method of claim 38, wherein: the action of uncoupling the
first component from the second component without removing the
second component from the recipient includes undoing pin and socket
connections that place the first component into electrical
communication with the second component.
44. The method of claim 38, further comprising: connecting an
apparatus to the second component such that the apparatus is in
electrical communication with the second component and mechanically
coupled to the second component.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 11/857,397 filed Sep. 18, 2007,
now U.S. Pat. No. 8,255,058 issued Aug. 28, 2012, which claims
priority from U.S. patent application Ser. No. 10/820,444, filed on
Apr. 8, 2004, which claims priority from Australian Provisional
Application No 2003901696, filed Apr. 9, 2003, the contents of
which are incorporated herein by reference.
BACKGROUND
Field of the Invention
[0002] The present invention relates to a cochlear implant and in
particular to an MRI-compatible implantable component of a cochlear
implant.
[0003] Cochlear implant systems bypass the hair cells in the
cochlea and directly deliver electrical stimulation to the auditory
nerve fibres, thereby allowing the brain to perceive a hearing
sensation resembling the natural hearing sensation normally
delivered to the auditory nerve.
[0004] Typically, cochlear implant systems have consisted of
essentially two components, an external component commonly referred
to as a processor unit and an internal implanted component commonly
referred to as a stimulator/receiver unit. Traditionally, both of
these components have cooperated together to provide the sound
sensation to a user.
[0005] The external component may consist of a microphone for
detecting sounds, a speech processor that converts the detected
sounds, particularly speech, into a coded signal, a power source
such as a battery, and an external transmitter antenna.
[0006] The coded signal output by the speech processor is
transmitted transcutaneously to the implanted stimulator/receiver
unit that can be situated within a recess of the temporal bone of
the implantee. This transcutaneous transmission occurs via the
external transmitter antenna which is positioned to communicate
with an implanted receiver antenna provided with the
stimulator/receiver unit.
[0007] The implanted stimulator/receiver unit traditionally
includes a receiver antenna that receives the coded signal and
power from the external processor component, and a stimulator that
processes the coded signal and outputs a stimulation signal to an
intracochlear electrode assembly which applies the electrical
stimulation directly to the auditory nerve producing a hearing
sensation corresponding to the original detected sound.
[0008] The commonly accepted method of providing the implanted
stimulator with power and information is to transmit RF-power via
an inductively coupled antenna coil system. In such a system, the
external transmitter coil is usually positioned on the side of an
implantee's head directly facing the implanted coil of the
stimulator/receiver unit to allow for the transmission of the coded
sound signal and power from the speech processor to the implanted
unit. Such transmitters usually have a coil formed by a small
number of turns of a single or multi-strand wire and a magnet at or
near the hub of the coil. The magnet holds the transmitter coil in
place due to magnetic attraction with a magnet of the implanted
unit.
[0009] The implanted magnet can pose problems for those cochlear
implant implantees that may be required to undergo magnetic
resonance imaging (MRI). In this regard, although studies have
indicated that MRI presents no major risk to such implantees, the
magnetic fields used in MRI procedures have been shown to exert a
torque force on the implanted magnet. This torque force, if
significantly large, such as may be the case if a high field
strength MRI is undertaken, has the potential to cause undesirable
consequences such as dislodgement of the magnet from its casing as
well as discomfort to the implantee. There is also the potential
for significant distortion of the image obtained by MRI due to the
presence of the magnet in the implantee's head, which may
significantly negate the usefulness of the process.
SUMMARY
[0010] Throughout this specification the word "comprise", or
variations such as "comprises" or "comprising", will be understood
to imply the inclusion of a stated element, integer or step, or
group of elements, integers or steps, but not the exclusion of any
other element, integer or step, or group of elements, integers or
steps.
[0011] In a first aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component:
[0012] the system being characterised in that an outer surface of
the magnet, or a casing for the magnet, of the implantable receiver
component has an engagement surface that is engageable with a
complementary engagement surface formed in a mounting of the
implantable receiver component.
[0012] In a second aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component;
[0014] the system being characterised in that the magnet of the
implantable receiver component is housable within a pocket formed
in a suitable biocompatible flexible mounting, said pocket having a
restricted opening formed therein through which the magnet is
insertable but which is sized to retain the magnet within the
pocket following insertion.
[0013] In a third aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component;
[0016] the system being characterised in that the magnet of the
implantable receiver component is housed within a suitable
biocompatible flexible mounting, said mounting having one or more
indicia thereon or therein that identify the location of the magnet
within the mounting
[0014] In a fourth aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component;
[0018] the system being characterised in that the magnet is
releasably held within the receiver component by one or more
retaining devices.
[0015] In a fifth aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component;
[0020] the system being characterised in that the magnet of the
implantable receiver component is housed within a recess formed in
a suitable biocompatible flexible mounting, said recess being
locatable adjacent the skull of the implantee in use thereby
ensuring the magnet is held in the recess between the receiver
component and the skull of the implantee
[0016] In a sixth aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, the external transmitter
unit having a magnet positioned therein and the implantable
receiver component having a magnetised insert positioned therein to
allow transcutaneous alignment of said external transmitter unit
and said implantable receiver component; [0022] the magnetised
insert of the implantable receiver component having a first end and
a second end and increasing in width away from said first end
towards said second end, the first end being positionable closer to
the skin of the implantee in use to ensure self-centering of the
magnet of the external transmitter unit with the magnetised insert
of the receiver component
[0017] In a seventh aspect, there is provided a magnetic alignment
system for a transcutaneous transmitter/receiver system, said
magnetic alignment system comprising an external transmitter unit
and an implantable receiver component, both the external
transmitter unit and the implantable receiver component having a
magnet positioned therein to allow transcutaneous alignment of said
external transmitter unit and said implantable receiver component;
[0024] the system being characterised in that the implantable
receiver component is detachably connectable to an implantable
tissue stimulator device.
[0018] In an eighth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component; wherein an outer surface of the magnet, or a
casing for the magnet, of the implantable receiver component has an
engagement surface that is engageable with a complementary
engagement surface formed in a mounting of the implantable receiver
component.
[0019] In a ninth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component and wherein the magnet of the implantable
receiver component is housable within a pocket formed in a suitable
biocompatible flexible mounting, said pocket having a restricted
opening formed therein through which the magnet is insertable but
which is sized to retain the magnet within the pocket following
insertion.
[0020] In a tenth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component; wherein the magnet of the implantable receiver
component is housed within a suitable biocompatible flexible
mounting, said mounting having one or more indicia thereon or
therein that identify the location of the magnet within the
mounting
[0021] In an eleventh aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component; wherein the magnet is releasably held within
the receiver component by one or more retaining devices.
[0022] In a twelfth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component; wherein the magnet of the implantable receiver
component is housed within a recess formed in a suitable
biocompatible flexible mounting, said recess being locatable
adjacent the skull of the implantee in use thereby ensuring the
magnet is held in the recess between the receiver component and the
skull of the implantee.
[0023] In a thirteenth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein the external
transmitter unit has a magnet positioned therein and the
implantable receiver component has a magnetised insert positioned
therein to allow transcutaneous alignment of said external
transmitter unit and said implantable receiver component; [0031]
the magnetised insert of the implantable receiver component having
a first end and a second end and increasing in width away from said
first end towards said second end, the first end being positionable
closer to the skin of the implantee in use to ensure self-centering
of the magnet of the external transmitter unit with the magnetised
insert of the receiver component.
[0024] In a fourteenth aspect, there is provided a cochlear implant
system comprising an external transmitter unit positionable on the
outside of an implantee's head and an implantable receiver
component positionable subcutaneously, wherein said external
transmitter unit and said implantable receiver component each
comprise a magnet therein to hold the external transmitter unit
substantially in transcutaneous alignment with the implantable
receiver component; the system being characterised in that the
implantable receiver component is detachably connectable to an
implantable cochlea stimulator device
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] By way of example only, exemplary embodiments are now
described with reference to the accompanying drawings, in
which:
[0026] FIG. 1 is a pictorial representation of a cochlear implant
system;
[0027] FIG. 2a is a schematic view of a magnet and mounting of one
example of the invention;
[0028] FIG. 2b depicts another arrangement for mounting the magnet
in the receiver component;
[0029] FIG. 3 depicts a still further arrangement for mounting the
magnet in the receiver component;
[0030] FIGS. 3a and 3b depict a still further arrangement for
mounting the magnet in the receiver component;
[0031] FIGS. 4, 4a and 4b depict arrangements for identifying the
location of the magnet in the mounting of the receiver
component;
[0032] FIGS. 5a and 5b depict an alternative arrangement for
mounting the magnet in the receiver component;
[0033] FIGS. 6a and 6b depict another arrangement for ensuring
magnetic alignment of the receiver component with the external
transmitter component;
[0034] FIG. 7a depicts a further arrangement for mounting the
magnet in the receiver component;
[0035] FIG. 7b depicts how the magnet can be removed from the
receiver component shown in FIG. 7a;
[0036] FIGS. 8a and 8b depict an arrangement in which the receiver
coil can be disconnected from the stimulator component; and
[0037] FIGS. 9a, 9b, 9c, 10a, and 10b depict various arrangements
for retaining the magnet in the receiver component using one or
more manipulable clips.
DETAILED DESCRIPTION
[0038] Exemplary embodiments of a magnetic alignment system
according to the present invention are generally depicted in the
accompanying drawings as part of a cochlear implant system.
[0039] As depicted pictorially in FIG. 1, the magnetic alignment
system 10 of a cochlear implant system comprises an external
transmitter unit 11 and an implantable receiver component 12.
[0040] The external transmitter unit 11 comprises a transmitter
antenna coil 13 which transmits coded signals to the implantable
receiver component 12 via a radio frequency (RF) link.
[0041] The implantable receiver component 12 of the system
comprises a receiver antenna coil 14 for receiving power and data
from the transmitter coil 13 and a stimulator unit 15 within a
housing 16. A cable 17 extends from the stimulator unit 15 to the
cochlea and terminates in an electrode array 18. The signals
received are applied by the array 18 to the basilar membrane 19
thereby stimulating the auditory nerve 20.
[0042] The receiver coil 14 typically comprises a wire antenna coil
comprised of at least one and preferably two turns of electrically
insulated platinum or gold wire.
[0043] The implantable receiver component 12 has a magnet to allow
transcutaneous alignment of the external transmitter unit 11 (which
also has a magnet 9) and the implantable receiver component 12.
[0044] The electrical insulation of the antenna coil is provided by
a flexible silicone molding. In use, the implantable receiver
component 12 can be positioned in a recess of the temporal bone
adjacent the ear of an implantee.
[0045] Arrangements for preventing any or at least reducing
substantial movement of the magnet of a transcutaneous
transmitter/receiver system, such as a cochlear implant system,
while a recipient is undergoing MRI scans of relatively low field
strengths and arrangements that allow removal of the magnet from
within the implantee if necessary, (such as when the recipient is
to undergo MRI scans of relatively high field strengths) are
depicted in the remaining drawings.
[0046] In the embodiment depicted in FIG. 2a, the implantable
receiver component of a cochlear implant system has a magnet 21 and
a mounting 22. An outer surface of the magnet 21 has an engagement
surface that is engageable with a complementary engagement surface
formed in the mounting 22. The engagement between the magnet 21 and
the mounting 22 minimises movement of the magnet, particularly when
a patient undergoes an MRI procedure. Examples of the engagement
surface and the complementary engagement surface are described in
more detail below.
[0047] In FIG. 2a, the magnet 21 has two extension members 23 that
extend from opposite sides of the magnet. The magnet 21 may be
received by the mounting 22 which is shown in FIG. 2 as a ring
24.
[0048] The ring 24 has at least one recessed portion 25. In an
exemplary embodiment, the ring 24 includes two recessed portions 25
although in FIG. 2a, the second recessed portion is obscured from
view. The recessed portions 25 receive the extension members 23 of
the magnet 21 and hold the magnet in place within the ring 24.
[0049] The ring further includes two slots 26 in an inner surface
27 of the ring 24. The slots 26 extend from an upper surface 28 of
the ring 24 to a lower surface 29 of the ring 24, i.e. through the
thickness of the ring 24.
[0050] The magnet 21 may be relatively lowered into the center of
the ring 24 such that the extension members 23 pass through slots
26. When moved beyond the lower surface 29 of the ring 24, the
magnet is then rotatably moveable relative to the ring 24.
[0051] The magnet 21 may be rotated until the extension members
align with the recessed portions 25.
[0052] The ring 24 may sit on, or at least partially within, a
resilient silicone body of the implantable receiver component. To
insert the magnet 21 into the center of the ring, a degree of force
is therefore required to cause the extension member 23 to pass
through the slots 26 and beyond the lower surface 29 of the ring
24. Once the magnet 21 is rotated and the extension members 23 are
in alignment with the recessed portions 25, release of any force
applied to the magnet 21 will result in the silicone body causing
the extension members 23 to move up and away from the lower surface
29 of the ring and into the recessed portions 25. With the
extension members 23 housed within the recessed portions 25, the
magnet 21 is no longer rotatably moveable relative to the ring 24
(unless a degree of downward force is again applied to the magnet
21 to dislodge the extension members from the recessed
portions).
[0053] The magnet 21 is, therefore, substantially but removably
locked in place within the mounting 22.
[0054] Referring now to FIG. 2b, an alternative arrangement is
shown in which the extension members 23a extend inwardly from the
ring 24, and are arranged to engage with corresponding recessed
portions 25a provided on the magnet 21. The number of slots 26a is
shown as two, however, it is envisaged that one larger extension
member 23a on the ring 24 could be used together with a
corresponding single slot on the magnet 21.
[0055] Further, the ring 24 as shown in FIG. 2a has a series of
holes 30 extending therethrough. The silicone of the implantable
receiver component may extend through the holes 30 and provides a
means of securing the ring 24 to the silicone body of the
implantable receiver component. In this regard, portions of
silicone may extend through the holes 30 and essentially act as
rivets to mechanically lock the ring 24 in place. This added level
of security may be desirable when the magnet is subjected to MRI
and particularly to high field strengths.
[0056] In this aspect, the engagement surface of the magnet or the
magnet casing can be a screw thread. The complementary engagement
surface of the mounting can also be a screw thread that is formed
in the mounting. In one embodiment, the mounting has a ring member
mounted therein. The internal surface of the ring member may form
the complementary engagement surface and may be a screw thread. The
ring member can be made of a ceramic or plastics material. The
mounting can be formed from a suitable biocompatible silicone.
[0057] As depicted in FIG. 3, the magnet can be screwed into or
unscrewed from the mounting.
[0058] In FIG. 3, the outer surface of magnet 61 has a screw thread
62 formed therein. The screw thread 62 is engageable with a
complementary thread 63 formed in a mounting ring 64 within the
implantable component body (here depicted as 65). The mounting ring
64 can be made of a metal, ceramic or plastics material while the
body 65 can be formed from a suitable biocompatible material, such
as silicone.
[0059] As depicted, a top surface of the magnet 61 can have a slot
66 formed therein that can receive a tool, such as an allen key 66a
as shown, or a screwdriver or the like, to facilitate turning of
the magnet and its removal from the mounting ring 64.
[0060] In another embodiment, the engagement surface of the magnet
may be held in place within the mounting by friction fit. As
described in more detail below, the outer surface of the magnet, or
casing of the magnet, can be shaped in a specific configuration,
allowing for insertion of the magnet or part of the magnet into the
mounting element. In this regard, the complementary engagement
surface of the mounting will be compatible with the shape of the
outer surface of the magnet or magnet casing such that the outer
surface can be inserted into the mounting element. Once the outer
surface of the magnet or magnet casing has been at least partially
inserted into the mounting element, the magnet or magnet casing may
be rotated, for example a 1/4 or 1/2 turn, thereby causing the
shape of the engagement surface of the magnet or magnet casing to
no longer be compatible with the shape of the complementary
engagement surface of the mounting element. This thereby provides
an interference fit preventing inadvertent removal of the magnet
from the mounting element. In this embodiment, the magnet may be
easily removed by merely rotating the magnet the appropriate amount
such that the shape of the engagement surface of the magnet means
is compatible with the shape of the complementary engagement
surface of the mounting element, thereby allowing easy removal of
the magnet.
[0061] This particular embodiment is depicted in FIG. 3a wherein
magnet 61 is provided with a pedestal element 61a for securing
within the mounting element 64. In the depicted embodiment, the
mounting element 64, is substantially trapezoidal in shape with two
upright walls 64a, being curved in configuration. The pedestal
element 61a of the magnet 61 has a similar shape to that of the
mounting element 64, namely it has a shape consisting of two
substantially parallel sides joined at both ends by curved
portions. The pedestal is remote from the bottom face of the magnet
61, thereby forming a space between the pedestal element 61a and
the magnet 61. The inner surfaces of the upright walls 64a of the
mounting element 64 can be provided with a recess to receive the
curved end portions of the pedestal element 61a when the pedestal
is placed within the mounting element 64 for engagement.
[0062] In this regard, the magnet 61 is rotatable relative to the
mounting. The magnet may be rotated 90 degrees to the position
shown in FIG. 3a for locating within the mounting element 64. Once
the magnet 61 is placed in position with the pedestal element 61a
located between the walls 64a of the mounting element 64, the
magnet is then rotated 90 degrees such that the curved walls of the
pedestal element 61a are received within the recessed curved walls
of the mounting element 64. In this regard, the magnet is secured
in place and is fixed within the mounting element 64 as shown in
FIG. 3b. To remove the magnet 61 from the mounting element 64 in
the event, for example, of an MRI procedure, the magnet 61 is
rotated such that the pedestal element 61a is no longer held in
place within the walls 64a of the mounting element. The magnet can
then be relatively easily removed. A screwdriver or other such tool
can be used to assist in this procedure, via the slot 66.
[0063] As is shown in FIGS. 3a and 3b as the dotted line and the
hashed area respectively, the magnet 61 and mounting element 64 are
preferably secured in a flexible biocompatible material such as
silicone. In this regard, the silicone can be arranged so as to
overlap the walls of the mounting element 64 such that when the
magnet 61 is placed in position for securing, as described above,
the surrounding material may be compressed between the magnet 61
and the mounting element 64. In this regard, the compression force
may aid in securing the magnet in place when rotated into the
secured position. Further, such an arrangement may further seal the
arrangement form the ingress of body fluids into the mounting
element 64.
[0064] In another embodiment, a spring-type force can be provided
to aid in the interference fit by providing a bias force between
the engagement surfaces of the magnet and the mounting element,
such that when the two surfaces are in non-alignment, the magnet
will be securely held in place. Such a biasing force can be
provided by placing a spring means or spring member in the mounting
for receiving the magnet, or by providing a compressive material
such as silicone within the mounting, that is compressed once the
magnet is inserted into the mounting and provides a force that
biases the magnet against the mounting.
[0065] A further aspect of the invention is depicted in FIGS. 4, 4a
and 4b. The magnet (here depicted as 51) of the implantable
receiver component is housed within a suitable biocompatible
flexible silicone mounting 52. In FIG. 4, the mounting 52 has a
circular indentation 53 formed therein that acts as an indicia and
serves to assist in identifying the location of the magnet 51
within the mounting 52. During surgery to remove the magnet 51, the
ring 53 will indicate to the surgeon the location of the magnet 51
within the mounting 52. The indentation can also serve as a guide
to a scalpel blade used to cut through the mounting 52 to access
the magnet 51.
[0066] In the embodiment depicted in FIGS. 4a and 4b, the indicia
can comprise two or more holes 54 formed in the silicone. The holes
54 again act as guides to a surgeon having to cut the magnet 51
from the mounting 52. That is, they identify where the mounting 52
should be cut to allow removal of the magnet 51 held therein.
[0067] FIGS. 5a and 5b depict a still further arrangement wherein
the magnet 71 of the implantable receiver component is housed
within a pocket 72 formed in a wall of the biocompatible flexible
mounting. The pocket 72 has a restricted opening 73 formed therein
through which the magnet 71 can be inserted but which is sized to
retain the magnet 71 within the pocket 72 following insertion
during normal use.
[0068] FIGS. 6a and 6b depict a still further arrangement, in which
the external transmitter unit (not depicted in FIGS. 6a and 6b) has
a magnet positioned therein while the implantable receiver
component (here depicted as 80) has a conical, non-magnetised
ferro-magnetic insert 81 positioned therein to allow transcutaneous
alignment of the external transmitter unit and the implantable
receiver component. The non-magnetised insert 81 of the implantable
receiver component has a first end and a second end and increases
in width away from the first end towards the second end, the first
end being adapted to be positioned closer to the skin of the
implantee to ensure self-centering of the magnet of the external
transmitter unit with the insert 81 of the receiver component.
While depicted as a conical structure, the magnetised insert be
other shapes such as a frusto-conical shape.
[0069] The non-magnetised insert 81 can be mounted in a
non-magnetic support within the receiver component. In one
embodiment, the support can be a titanium case 82 as depicted in
FIG. 6b. In another embodiment, as depicted in FIG. 6a, a suitable
non-magnetic material, such as plastic, ceramic or titanium, stop
member 83 can lock the insert 81 in the receiver component.
[0070] While the insert 81 can be removable, the use of a
non-magnetised insert 81 rather than a magnet has the advantage of
reducing the magnetic force on the receiver component during an MRI
scan if it is left in place.
[0071] In FIGS. 7a and 7b, the magnet 91 of the implantable
receiver component (here depicted as 92) is housed within a recess
93 formed in a suitable biocompatible flexible mounting. The recess
93 is adapted to be located adjacent the skull 94 of the implantee
in use thereby ensuring the magnet 91 is held in the recess 93
between the receiver component 92 and the skull 94 of the
implantee.
[0072] In this embodiment, the magnet 91 can be removed from the
recess by incising the skin of the implantee and then gently
lifting the receiver component 92 away from the skull a distance
sufficient to allow a surgeon to reach under the receiver component
and remove the magnet 91 from the recess 93, as is depicted in FIG.
7b.
[0073] FIGS. 8a and 8b depict a further arrangement in which the
mounting 101 housing the receiver coil 102 and magnet 103 is
detachably connectable to an implantable tissue stimulator device
(here depicted as 104). Electrical connection is made between the
receiver component and the tissue stimulator device when the
component is connected to the stimulator device. A pin and socket
arrangement can be used to provide the electrical connection.
[0074] As depicted, the electrical connection is made between the
coil 102 and the circuitry of the tissue stimulator device 104 by a
pin and socket arrangement 105. Once connection is made, the pin
and socket arrangement is preferably constructed such that there is
no ingress of bodily fluids into either the stimulator device 104
or the mounting 101. In one embodiment, the socket can be mounted
to the stimulator device and the pin or pins to the receiver
component. An arrangement where the socket is part of the receiver
component and the pin or pins are part of the stimulator device can
be equally envisaged.
[0075] If the implantee is to undergo an MRI scan, an incision can
be made in the implantee, and the receiver component detached from
the tissue stimulator device. The entire receiver component, as
defined in this aspect, is then removed rather than just the
magnet. Once the MRI scan is complete, the receiver component can
be re-implanted and the necessary connection again made between the
receiver component and the stimulator device.
[0076] Mounting 101 is detachable from the tissue stimulator device
104 and may be removed prior to an MRI procedure. Once the MRI scan
is complete, the mounting 101 can be re-implanted and the necessary
connection again made between the coil 102 and the stimulator
device 104.
[0077] In FIGS. 9a, 9b, 9c, 10a and 10b various systems that rely
on one or more clips to removably hold the magnet within the
receiver component are depicted.
[0078] The clips can be mounted on the receiver component and
adapted to engage the magnet positioned therein or thereon. In
another embodiment, the clips can be mounted to the magnet or a
casing thereof and are engageable with the receiver component. The
clips may be manipulable by a surgeon.
[0079] FIG. 9a depicts a compression clip 111 that can be used to
compress a silicone pocket 112 around a magnet (here depicted as
113). The clip 111 can be removed by a surgeon if removal of the
magnet 113 is required.
[0080] In the embodiment depicted in FIGS. 9b and 9c, two clips 114
are mounted on the magnet 113 and are engageable with a socket
member 115 that is itself removably engageable in the receiver
component (here depicted as 116). The socket member 115 has a main
member 120 and two wing members 117. The wing members 117 are
engageable within recesses 118 extending laterally from a main
recess 119 formed in the receiver component 116. When the socket
member 115 is positioned within the main recess 119 and the wing
members 117 are engaged with the lateral recesses 118, the main
member 120 is suspended across the main recess 119.
[0081] The clips 114 of the magnet 113 are preferentially biased
inwardly and as such must be moved out and around the main member
120 on insertion. Once the lower ends of the clips 114 have moved
relatively below the main member 120, the clips 114 can be released
and so engage under the main member 120. If it is desired to remove
the magnet 113, the clips 114 are pulled relatively apart by the
surgeon thereby allowing the magnet 113 to be drawn up and out of
the main recess 119.
[0082] An alternative arrangement for using a clip to retain the
magnet 113 in the receiver component 116 is depicted in FIGS. 10a
and 10b. In this embodiment, a clip 121 is positioned underneath
the magnet 113. The clip 121 is supported in the silicone body of
the receiver component and has two lips 122 that preferentially
hold the magnet 113 in place during normal use. If it is desired to
remove the magnet 113, the lips 122 are pushed down into the
resilient silicone body 116 and pivot about uprights 123 so
allowing the magnet 113 to be popped out of the receiver component
116 in the direction of arrow A.
[0083] The cochlear implant system described above enables an
implantee to undergo an MRI procedure without removing the magnet
of an implant, such as a cochlear implant, or provides a system
enabling easy removal of the magnet to facilitate an MRI procedure
at relatively higher filed strengths. Such a system is particularly
useful for those implantees requiring regular MRI scans.
[0084] It will be appreciated by persons skilled in the art that
numerous variations and/or modifications may be made to the
invention as shown in the specific embodiments without departing
from the spirit or scope of the invention as broadly described. The
present embodiments are, therefore, to be considered in all
respects as illustrative and not restrictive.
* * * * *