U.S. patent application number 13/685668 was filed with the patent office on 2013-06-06 for cochlear implant drug delivery device.
The applicant listed for this patent is Kristine Debruyne, Dirk Fiedler, Thomas Kaiser, Ben Kloeck, Dusan Milojevic, John Parker. Invention is credited to Kristine Debruyne, Dirk Fiedler, Thomas Kaiser, Ben Kloeck, Dusan Milojevic, John Parker.
Application Number | 20130144370 13/685668 |
Document ID | / |
Family ID | 32474715 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130144370 |
Kind Code |
A1 |
Debruyne; Kristine ; et
al. |
June 6, 2013 |
COCHLEAR IMPLANT DRUG DELIVERY DEVICE
Abstract
Devices for the delivery of a bioactive substance to a cochlea
and methods of delivery thereof. The devices include means to allow
the release of the bioactive substance within a cochlea.
Inventors: |
Debruyne; Kristine;
(Mechelen, BE) ; Fiedler; Dirk; (Elanora heights,
AU) ; Kaiser; Thomas; (Mechelen, BE) ; Kloeck;
Ben; (Mechelen, BE) ; Milojevic; Dusan;
(Westleigh, AU) ; Parker; John; (Roseville,
AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Debruyne; Kristine
Fiedler; Dirk
Kaiser; Thomas
Kloeck; Ben
Milojevic; Dusan
Parker; John |
Mechelen
Elanora heights
Mechelen
Mechelen
Westleigh
Roseville |
|
BE
AU
BE
BE
AU
AU |
|
|
Family ID: |
32474715 |
Appl. No.: |
13/685668 |
Filed: |
November 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13404933 |
Feb 24, 2012 |
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13685668 |
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10536714 |
Aug 9, 2006 |
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PCT/AU03/01584 |
Nov 28, 2003 |
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13404933 |
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Current U.S.
Class: |
607/137 ;
607/116 |
Current CPC
Class: |
A61L 27/54 20130101;
A61N 1/05 20130101; A61K 9/0046 20130101; A61P 41/00 20180101; A61M
2210/0668 20130101; A61N 1/0541 20130101; A61L 2300/00 20130101;
A61M 31/00 20130101; A61L 31/16 20130101; A61L 2430/14
20130101 |
Class at
Publication: |
607/137 ;
607/116 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2002 |
AU |
2002952995 |
Nov 29, 2002 |
AU |
2002952997 |
Nov 29, 2002 |
AU |
2002952998 |
Claims
1-50. (canceled)
51. An implantable electrode array assembly configured to stimulate
tissue of a recipient, comprising: an elongate assembly configured
to be inserted into a recipient, the elongate assembly including at
least one electrode, wherein at least a portion of the elongate
assembly contains a bio-active substance.
52. The implantable electrode array assembly of claim 51, wherein:
one or more portions of the elongate assembly are formed of a
porous material.
53. The implantable electrode array assembly of claim 51, wherein:
the elongate assembly includes one or more members impregnated with
the bio-active substance.
54. The implantable electrode array assembly of claim 53, wherein:
at least one of the one or more members impregnated with the
bio-active substance is located on an outer face of the elongate
assembly.
55. The implantable electrode array assembly of claim 51, wherein:
the elongate assembly includes a portion formed from a
bio-compatible polymeric material, wherein the elongated assembly
is configured such that the bio-active substance diffuses from the
bio-compatible polymeric material following implantation into the
recipient.
56. The implantable electrode array assembly of claim 55, further
comprising: an elongate member, wherein the bio-compatible
polymeric material is at least partially encapsulated within the
elongate member.
57. The implantable electrode array assembly of claim 55, wherein:
the bio-compatible polymeric material is located at or
approximately at the surface of the elongate assembly.
58. The implantable electrode array assembly of claim 51, wherein:
the elongate assembly includes one or more openings which at least
partially expose the bio-active substance to an ambient environment
of the elongate assembly.
59. The implantable electrode array assembly of claim 51, wherein:
the bio-active substance is located in a portion of the electrode
array assembly having an outer surface that is substantially flush
with the outer profile surface of the elongate assembly.
60. The implantable electrode array assembly of claim 51, wherein:
the bio-active substance is located in a portion of the electrode
array assembly having an outer surface that is recessed relative to
the outer profile surface of the elongate assembly.
61. The implantable electrode array assembly of claim 51, wherein:
the bio-active substance is contained in one or more portions of
the elongate assembly, the one or more portions of the elongate
assembly containing the bio-active substance collectively extending
for a majority of the length of the elongate assembly.
62. The implantable electrode array assembly of claim 51, wherein:
the portion of the elongate assembly that contains the bio-active
substance has a diameters that are taken at locations along a
longitudinal direction of extension of the elongate assembly that
are constant.
63. The implantable electrode array assembly of claim 51, wherein:
a ratio of a cross-sectional area of the portion of the elongate
assembly that contains the bio-active substance when taken normal
to a longitudinal direction of the elongate assembly to a
cross-sectional area encompassing an outer profile of the elongate
assembly is about constant when the cross-sections are taken at
locations along the longitudinal direction of extension of the
elongate assembly.
64. The implantable electrode array assembly of claim 51, wherein:
the elongate assembly includes an elongate member formed from a
material consisting essentially of silicone; and the portion
containing the bio-active substance is formed from polymeric
material.
65. The implantable electrode array assembly of claim 51, wherein:
the portion containing the bio-active substance is comprised of a
biodegradable material.
66. The implantable electrode array assembly of claim 51, wherein:
the portion containing the bio-active substance is separate from
the at least one electrode.
67. The implantable electrode array assembly of claim 51, wherein:
the portion containing the bio-active substance includes a porous
portion having the bio-active substance disposed therein.
68. The implantable electrode array assembly of claim 67, wherein:
elongate assembly is configured such that the bio-active substance
migrates from the pores to the recipient after implantation of the
elongate assembly in the recipient.
69. The implantable electrode array assembly of claim 51, wherein:
elongate assembly is configured such that the bio-active substance
migrates, diffuses and/or is released from the portion containing
the bio-active substance after implantation of the elongate
assembly into the recipient.
70. The implantable electrode array assembly of claim 67, wherein:
the porous portion is a porous body that has a substantially
uniform porosity.
71. The implantable electrode array assembly of claim 67, wherein:
the porous portion has a varying porosity.
72. The implantable electrode array assembly of claim 67, wherein:
at least some of the pores of the porous portion are
interconnected.
73. The implantable electrode array assembly of claim 67, wherein:
pores of the porous portion located closer to a distal end of the
elongate assembly have a diameter and/or length different than
those located further from the distal end of the elongate
assembly.
74. The implantable electrode array assembly of claim 67, wherein:
pores of the porous portion located closer to a distal end of the
elongate assembly have a diameter and/or length greater than those
located further from the distal end of the elongate assembly.
75. The implantable electrode array assembly of claim 51, wherein
the bio-active substance is selected from the group consisting of a
pharmaceutical agent, an anti-inflammatory substance, an
antibiotic, a steriod, a substance that reduces a resisting neuron
potential of neurons within the cochlea, a substance that promotes
healing, a substance that prevents bleeding and/or prevents
excessive bleeding, a substance that prevents the growth of tissue
and a substance that promotes more efficient neural
stimulation.
76. The implantable electrode array assembly of claim 51, wherein:
the bio-active substance is partially encapsulated within the
elongate assembly and partially exposed to the exterior of the
elongate assembly.
77. The implantable electrode array assembly of claim 51, wherein:
the portion of the elongate assembly that contains the bio-active
substance has diameters that are taken at locations along a
longitudinal direction of extension of the elongate assembly that
vary.
78. The implantable electrode array assembly of claim 51, wherein:
the portion of the elongate assembly that contains the bio-active
substance has diameters that are taken at locations along a
longitudinal direction of extension of the elongate assembly, the
diameters at locations closer to a distal end of the elongate
assembly being less than diameters at locations farther from the
distal end of the elongate assembly.
79. The implantable electrode array assembly of claim 51, wherein:
elongate assembly is configured such that the bio-active substance
migrates, diffuses and/or is released from the portion containing
the bio-active substance after implantation of the elongate
assembly into the recipient.
80. The implantable electrode array assembly of claim 67, wherein:
at least some of the pores of the porous portion have a
substantially constant size along their length.
81. The implantable electrode array assembly of claim 67, wherein:
at least some of the pores of the porous portion have a varying
size along their length.
82. The implantable electrode array assembly of claim 67, wherein:
at least some of the pores of the porous portion have a
substantially uniform cross-sectional shape along their length.
83. The implantable electrode array assembly of claim 67, wherein:
at least some of the pores of the porous portion have a varying
cross-sectional shape along their length.
84. The implantable electrode array assembly of claim 51, wherein:
the portion of the elongate assembly that contains the bio-active
substance is located away from a geometrically centered
longitudinal axis of the elongate assembly.
85. The implantable electrode array assembly of claim 84, wherein:
the portion of the elongate assembly that contains the bio-active
substance is located closer to a first location on a surface of the
elongate assembly than a second location on the surface of the
elongate assembly; the first and second locations are located on
opposite sides of the elongate assembly; and the at least one
electrode is located closer to the second location than the first
location.
86. The implantable electrode array assembly of claim 84, wherein:
the portion of the elongate assembly that contains the bio-active
substance is located on a first side of the geometrically centered
longitudinal axis of the elongate assembly; the at least one
electrode is located on a second side of the geometrically centered
longitudinal axis of the elongate assembly; and the first side is
opposite the second side relative to the geometrically centered
longitudinal axis of the elongate assembly.
87. The implantable electrode array assembly of claim 51, wherein:
the elongate assembly is configured to adopt a curved configuration
after insertion into a cochlea of the recipient to provide
stimulation to the cochlea; the portion of the elongate assembly
that contains the bio-active substance is located closer to a first
location on a surface of the elongate assembly than a second
location on the surface of the elongate assembly; the first
location is located on an outermost convex portion of the elongate
assembly after the elongate assembly has adopted the curved
configuration after insertion into the cochlea to stimulate the
cochlea; and the second location is located on an innermost concave
portion of the elongate assembly after it has adopted the curved
configuration after insertion into the cochlea to stimulate the
cochlea.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an implantable device and,
in particular, to an implantable device for use in delivering
pharmaceuticals to a cochlea following implantation of an electrode
assembly.
BACKGROUND OF THE INVENTION
[0002] Hearing loss, which may be due to many different causes, is
generally of two types, conductive and sensorineural. Of these
types, conductive hearing loss occurs where the normal mechanical
pathways for sound to reach the hair cells in the cochlea are
impeded, for example, by damage to the ossicles. Conductive hearing
loss may often be helped by use of conventional hearing aid
systems, which amplify sound so that acoustic information does
reach the cochlea and the hair cells.
[0003] In many people who are profoundly deaf, however, the reason
for deafness is sensorineural hearing loss. This type of hearing
loss is due to the absence of, or destruction of, the hair cells in
the cochlea which transduce acoustic signals into nerve impulses.
These people are thus unable to derive suitable benefit from
conventional hearing aid systems, because there is damage to or
absence of the mechanism for nerve impulses to be generated from
sound in the normal manner.
[0004] It is for this purpose that hearing implant systems have
been developed. Such 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.
[0005] Hearing implant systems have typically consisted of two key
components, namely an external component commonly referred to as a
processor unit, and an implanted internal component commonly
referred to as a receiver/stimulator unit. Traditionally, both of
these components have cooperated together to provide the sound
sensation to an implantee.
[0006] The external component has traditionally consisted of a
microphone for detecting sounds, such as speech and environmental
sounds, a speech processor that converts the detected sounds and
particularly speech into a coded signal, a power source such as a
battery, and an external antenna transmitter coil.
[0007] The coded signal output by the speech processor is
transmitted transcutaneously to the implanted receiver/stimulator
unit situated within a recess of the temporal bone of the
implantee. This transcutaneous transmission occurs through use of
an inductive coupling provided between the external antenna
transmitter coil which is positioned to communicate with an
implanted antenna receiver coil provided with the
receiver/stimulator unit. This communication serves two essential
purposes, firstly to transcutaneously transmit the coded sound
signal and secondly to provide power to the implanted
receiver/stimulator unit. Conventionally, this link has been in the
form of a radio frequency (RF) link, but other such links have been
proposed and implemented with varying degrees of success.
[0008] The implanted receiver/stimulator unit typically includes
the antenna receiver coil 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 through
a lead to an intracochlea electrode assembly which applies the
electrical stimulation directly to the auditory nerve producing a
hearing sensation corresponding to the original detected sound.
[0009] The electrode assembly is typically implanted through a
cochleostomy formed in the cochlea and comprises an array of
electrodes, with each electrode being arranged and constructed to
deliver a cochlea stimulating signal within a preselected frequency
range to an appropriate cochlea region. The electrical currents and
electric fields from each electrode stimulate the cilia disposed on
the modiolus of the cochlea. Several electrodes may be active
simultaneously.
[0010] There have been a number of proposals for delivering
bioactive substances to the cochlea that are beneficial in
promoting acceptance of the electrode assembly within the cochlea
and/or assisting in the function of the auditory nerve. One such
proposal is described in the present applicant's International
Application No PCT/AU01/01479 which describes use of a lumen within
the electrode assembly that delivers bioactive substances directly
within the cochlea following implantation of the assembly.
[0011] The present invention provides an alternative system for
delivering beneficial bioactive substances to the region of the
cochlea of a patient sad particularly an implantee of a hearing
implant.
[0012] Any discussion of documents, acts, materials, devices,
articles or the like winch has been included in the present
specification is solely for the purpose of providing a contest for
the present invention. It is not to be taken as an admission that
any or all of these matters form part of the prior art base or were
common general knowledge in the field relevant to the present
invention as it existed before the priority date of each claim of
this application.
[0013] 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.
[0014] Generally, the present invention provides a device that is
adapted to assist in the delivery of pharmaceutical treatment to
surrounding tissue following the insertion and positioning of an
electrode assembly. Typically, the electrode assembly is positioned
in order to apply electrical stimulation to a target region of
tissue via dedicated electrical stimulating electrodes. The present
invention is applicable to all types of tissue stimulating devices
such as hearing implants, deep brain implants, spinal cord implants
and any other Implantable devices that treat neurosensory or
motorsensory loss or dysfunction.
[0015] It is a preferred feature of the present invention to
provide a device that is adapted to assist the cochlea in its
recovery from trauma following the insertion of an electrode
assembly therein. The present invention is equally applicable to
conventional straight electrode assemblies and electrode assemblies
which are designed to conform with the inner wall of the
cochlea.
[0016] According to a first aspect, the present invention is a drug
delivery device comprising:
[0017] a resiliently flexible elongate member having a proximal end
and a distal end for implantation within a body;
[0018] wherein at least a portion of said elongate member is
comprised of a porous biocompatible material, at least some of the
pores having at least one bio-active substance disposed therein
prior to implantation, said at least one bioactive substance being
adapted to migrate from the pores following implantation of the
member.
[0019] In this aspect, the resiliently flexible elongated member
can form part of an implantable tissue-stimulating device having at
least one electrode mounted thereon.
[0020] In another embodiment of this aspect, the drag delivery
device can be separate to a tissue stimulating device but which
acts in conjunction with said tissue stimulating device.
[0021] According to a second aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0022] a resiliently flexible elongate member having a proximal end
and a distal end and at least one electrode mounted thereon between
said proximal and distal ends for delivering electrical
stimulation;
[0023] wherein at least a portion of said elongate member is
comprised of a porous biocompatible material, at least some of the
pores having at least one bioactive substance disposed therein
prior to implantation, said at least one bioactive substance being
adapted to migrate from the pores following implantation of the
member.
[0024] In a preferred embodiment of this invention, the device is a
cochlear.TM. implant electrode assembly, with the elongate member
adapted to be inserted through a cochleostomy formed, in the
cochlea and positioned therein.
[0025] In one embodiment, the elongate member can be comprised of
one or more porous portions. In one embodiment, the porous portions
can comprise the same material as the remainder of the elongate
member but having a plurality of pores disposed therethrough. In
one embodiment, the porous portions can comprise the same material
as the remainder of the elongate member but which has undergone a
processing step to render the portions foramina us. In another
embodiment, a majority, or the entire body, of the elongate member
can be porous.
[0026] In one embodiment of this aspect, the elongate member can be
formed from a silicone material.
[0027] in yet another embodiment, the porous portions can be formed
from a different material to that of the remainder of the elongate
member. In one embodiment, the porous portions can act as
electrodes for delivering electrical stimulation at the site of
implantation of the elongate member. In this embodiment, the
electrodes can be formed from a suitable porous metallic material.
The metallic material can be a suitable porous platinum. In another
embodiment, the porous portions can be formed from a suitable
porous metallic material, such as a porous platinum, mounted in the
elongate member but where the portions are not adapted to deliver
electrical stimulation.
[0028] In one embodiment, all of the electrodes mounted to the
elongate member can be formed from the suitable metallic material,
such as a porous platinum. In another embodiment, only some of the
electrodes can be porous, with some of the electrodes being formed
from a suitable relatively non-porous metallic material, such as
platinum as is discussed in further detail below.
[0029] In a still further embodiment, the device can further
comprise a sheath comprised at least in part of a porous material
disposed over at least a portion of the elongate member. In a
preferred embodiment, a majority of and, more preferably, the
entire elongate member can be sheathed in the porous material.
Still further, at least a majority and, more preferably, the entire
sheath is formed of a porous material.
[0030] According to a third aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0031] a resiliently flexible elongate member having a proximal end
and a distal end and at least one electrode mounted thereon between
said proximal and distal ends for delivering electrical
stimulation; and
[0032] a sheath comprised at least in part of a porous material
disposed over at least a portion of the elongate member;
[0033] wherein at least some of the pores of the sheath have at
least one bioactive substance disposed therein prior to
implantation, said at least one bioactive substance being adapted
to migrate from the pores following implantation of the member.
[0034] According to a fourth aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0035] a resiliently flexible elongate member having a proximal end
and a distal end; and
[0036] at least one electrode mounted on the elongate member
between said proximal end and said distal end for delivering
electrical stimulation;
[0037] wherein at least one of said at least one electrode is
comprised of a porous biocompatible material, at least some of the
pores having at least one bioactive substance disposed therein
prior to implantation, said at least one bioactive substance being
adapted to migrate from the pores following implantation of the
member.
[0038] In this aspect, said at least one electrode can be formed
from a suitable porous electrically conductive material. The
electrically conductive material can be a suitable porous metallic
material. The metallic material can be a suitable porous platinum.
In one embodiment of this aspect, all of the electrodes mounted to
the elongate member can fee formed from the suitable electrically
conductive material, such as a porous platinum. In another
embodiment, only some of the electrodes can fee porous, with some
of the electrodes being formed from a suitable relatively
non-porous metallic material/such as platinum.
[0039] In each of the above aspects, each pore of the porous
portion can be an individual pore within the portion, making no
interconnect ion with another pore in the portion. In this
embodiment, at least some or each of the pores can be aligned
and/or equally spaced with respect to each other. In another
embodiment, some of the pores can be interconnected with at least
some other pores within the porous portion in yet another
embodiment, the pores can be arranged in a random order with some
of the pores being interconnected with at least some of the other
pores and some of the pores not interconnected with any of the
other pores.
[0040] In a further embodiment, at least some of the pores or each
pore of the porous portion can be at least substantially uniform in
cross-sectional shape relative to each other. In another
embodiment, the pores can vary in cross-sectional shape from one to
at least some of the others.
[0041] In a still further embodiment, at least some- of the pores
or each pore of the porous portion can be substantially uniform in
diameter. In another embodiment, the pores can vary in diameter
from one to at least some of the others.
[0042] In yet another embodiment, at least some of the pores or
each pore of the porous portion can be of a substantially constant
diameter along its length. In another embodiment, at least some of
the pores or each pore can vary in diameter along its length.
[0043] In a still further embodiment, at least some of the pores or
each pore of the porous portion can have a substantially uniform
cross-sectional shape along its length. In another embodiment, at
least some of the pores or each pore can vary in cross-sectional
shape along its length.
[0044] In yet another embodiment, at least some of the pores or
each pore of the porous portion can be of a substantially constant
length. In another embodiment, at least some of the pores or each
pore can vary in length relative to at least some of the others in
that portion. In one embodiment, at least some of the pores can
have relatively extended lengths compared to other pores in that
portion.
[0045] In still another embodiment, at least some of the pores or
each pore of the porous portion can be at least substantially
linear. In another embodiment, at least some of the pores or each
pore of the porous portion cars be non-linear.
[0046] In a still further embodiment, at least some of the porous
portions or each porous portion can have substantially the same
number of pores per unit area. In another embodiment, at least some
of the porous portions or each porous portion can have differing
number of pores per unit area relative to that of at least some of
the other porous portions.
[0047] In yet another embodiment, at least some of the pores in
one, some or each of the porous portions can have relatively
smooth. Internal walls. In another embodiment, at least some of the
pores in one, some or each of the porous portions can have rippled
internal walls. The ripples can have a suitably small dimension to
preferably at least substantially prevent wetting of die cavities
thereby minimising friction between the bioactive substance and the
walls,
[0048] In one embodiment, the nature of the porosity between
separate porous portions of the device may be the same or vary from
one to at least some or all of the other portions. For example, the
dimension of the pores of a porous portion relatively close to the
distal end of the elongate member may be different to the
dimensions of the pores of a porous portion that is relatively
close to the proximal end of the elongate member. In this
embodiment, the portion relatively closer to the distal end can
have pores having a diameter and/or length greater than the pores
of the porous portion relatively closer to the proximal end of the
elongate member. In another embodiment, the relative porosity of
different portions can be essentially random.
[0049] In a further embodiment, at least some of the pores of the
porous portion can be preferably adapted to be at least
substantially closed when the elongate member is at least
substantially straight thereby preventing migration of any
bioactive substance held within said at least some pores from:
these pores. On adopting a curved configuration, said at least some
pores can be adapted to at least partially open allowing migration
of the bioactive substance therefrom.
[0050] In one embodiment, the bioactive substances can be free to
simply migrate from the pores of the porous portions following
implantation of the device. Its another embodiment, the bioactive
substance can be dispersed in a fluid and particularly an ionic
fluid that is preferably caused to migrate from the pores on
application of a suitable electrical field thereto. In another
embodiment, the bioactive substance can be dispersed in an ionic
solution that is allowed to diffuse from the pores and/or be
expelled therefrom under application of a suitable electric
field.
[0051] In a fifth aspect, the present invention is a method of
delivering at least one bioactive substance to a desired site of
action within a cochlea using a device as defined in the above
aspects and embodiments thereof, the method comprising the steps
of:
[0052] forming a cochleostomy;
[0053] inserting the elongate member through the cochleostomy;
[0054] allowing or causing the bioactive substance to migrate from
the elongate member into the cochlea.
[0055] The pores of the device may be at least partially filled by
dipping the elongate member in the bioactive substance for a
suitable time period. This step can be performed immediately after
manufacture of the elongate member. In another embodiment, the step
can be performed just prior to implantation of the member into the
implantee.
[0056] According to a sixth aspect, the present invention is a drug
delivery device comprising:
[0057] a resiliently flexible elongate member having a proximal end
and a distal end for implantation within a body;
[0058] wherein at least a portion of said elongate member is
comprised of a biocompatible polymeric material, having at least
one bioactive substance impregnated therein, said at least one
bioactive substance being adapted to diffuse from the polymeric
material following implantation of the member.
[0059] In this aspect, the resiliently flexible elongated member
can form part of an implantable tissue-stimulating device having at
least one electrode mounted thereon.
[0060] In another embodiment of this aspect, the drug delivery
device can be separate to a tissue stimulating device but which
acts in conjunction with said tissue stimulating device
[0061] According to a seventh aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0062] a resiliently flexible elongate member having a proximal end
and a distal end and at least one electrode mounted thereon between
said proximal arid distal ends for delivering electrical
stimulation;
[0063] wherein at least one portion of said elongate member is
comprised of a biocompatible polymeric material having at least one
bioactive substance impregnated therein prior to implantation, said
at least one bioactive substance being adapted to diffuse from the
polymeric material following implantation of the member.
[0064] In a preferred embodiment of this invention, the device is a
cochlear.TM. implant electrode assembly, with the elongate member
adapted to be inserted through a cochleostomy formed in the cochlea
and positioned therein.
[0065] In another embodiment, said portion of the biocompatible
polymeric material is fully or partially encapsulated inside the
material comprising the elongate member In another embodiment, it
can comprise a coating or be relatively near the surface of the
elongate member. In one embodiment, the portion extends into the
elongate member from at or adjacent the distal end. In this and
other embodiments, the portion can extend for a majority of the
length of the elongate member. In another embodiment, the portion
extends the entire length of the elongate member between the
proximal end and the distal end thereof. In this embodiment, said
portion can be of constant diameter along its length. In another
embodiment said portion can vary in diameter along its length. For
example, the diameter of said portion can decrease from the
proximal end towards the distal end of the elongate member.
[0066] In a still further embodiment, one or more openings can be
provided in the elongate member to allow bioactive substances in
said portion to diffuse from said portion and exit the elongate
member. An opening can be provided at the proximal end and/or the
distal end of the elongate member. In another embodiment, there can
be one or more openings between the proximal end and the distal
end. Where there is more than one opening, the openings can be
regularly or irregularly spaced along the elongate member.
[0067] In a still further embodiment, said at least one portion can
be disposed in the outer face of the elongate member. In one
embodiment, said portion can comprise a ring member disposed in the
outer lace of the elongate member. In another embodiment, said
portion can comprise a portion of a ring member, such as a
half-ring. In another embodiment, a number of portions can be
disposed along the locus of a ring formed in the outer surface of
the elongate member. In a still further embodiment, there can be
provided a plurality of rings or ring portions, such as half rings,
in the outer surface of the elongate member. In these embodiments,
the one or more portions can be at least substantially flush with
the outer surface of the elongate member. In another embodiment,
the one or more portions can stand proud of or be recessed in the
elongate member.
[0068] In a still further embodiment, the portions can be disposed
adjacent said one or more electrodes in the elongate member. In
another embodiment, at least one of said portions can be disposed
between each of the electrodes mounted on the elongate member.
[0069] In a still further embodiment, one of said portions can be
disposed around one, each of some or each of ah the electrodes
mounted in the elongate member. Where the electrode comprises a
ring or ring portion, the portion can comprise an annular or
part-annular member that surrounds the electrode.
[0070] In yet a further embodiment, the electrode can be disposed
around a portion of said biocompatible polymeric material. Where a
plurality of electrodes are mounted on the elongate member, some or
each of the electrodes can be disposed around separate portions of
said biocompatible polymeric material.
[0071] In one embodiment, the biocompatible polymeric material is
non-degradable and the bioactive substance may foe released by
gradual diffusion through the polymeric material. Initially,
bioactive substance molecules closest to the surface of the
polymeric material are released. As release continues, molecules
must travel a greater distance to reach the surface and thus the
time required for the release increases. Accordingly, the amount of
bioactive substance released may decrease with time.
[0072] According to an eighth aspect, the present invention is a
drug delivery device comprising:
[0073] a resiliency flexible elongate member having a proximal end
and a distal end for implantation within the body;
[0074] wherein at least a portion of said elongate member is
comprised of a biodegradable, biocompatible polymeric material
having at least one bioactive substance impregnated therein, said
at least one bioactive being adapted to be released upon at least
partial degradation of said polymeric material.
[0075] According to a ninth aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0076] a resiliently flexible elongate member having a proximal end
and a distal end and in least one electrode mounted thereon between
said proximal and distal ends for delivering electrical
stimulation;
[0077] wherein at least one portion of said elongate member is
comprised of a biodegradable, biocompatible polymeric material
having at least one bioactive substance impregnated therein, said
at least one bioactive being adapted to be released upon at least
partial degradation of said polymeric material.
[0078] The breakdown of the biodegradable polymeric material may
occur via gradual hydrolysis of the polymeric material or via
biodegradation of the polymer structure caused by chemical or
enzymatic processes.
[0079] Examples of suitable biodegradable polymers include
poly(acrylic acid), poly(ethylene glycol), poly(vinylpyrrolidone),
poly(hydroxybutyrate), poly(lactide-co-glycolide),
polyanhydrides.
[0080] According to a tenth aspect, the present invention is a
method of delivering at least one bioactive substance to a desired
site of action within a cochlea using a device as defined in the
sixth and seventh aspects, the method comprising the steps of:
[0081] forming a cochleostomy;
[0082] inserting the elongate member through the cochleostomy;
[0083] allowing the bioactive substance to diffuse from the
elongate member into the cochlea.
[0084] According to an eleventh aspect, the present invention is a
method of delivering at least one bioactive substance to a desired
site of action within a cochlea using a device as defined in the
eighth and ninth aspects, the method comprising the steps of:
[0085] forming a cochleostomy;
[0086] inserting the elongate member through the cochleostomy;
[0087] allowing or causing at least a portion of the biodegradable,
biocompatible polymeric material to at least partially degrade
allowing release of the bioactive substance therefrom.
[0088] According to a twelfth aspect, the present invention is an
implantable tissue-stimulating device comprising:
[0089] a lead;
[0090] a resiliency flexible elongate member extending from the
lead and having a proximal end and a distal end and at least one
electrode mounted thereon between said proximal and distal ends for
delivering electrical stimulation; and
[0091] a bioactive substance delivery means adapted to deliver at
least one bioactive substance to the implantee at a location spaced
from the distal end of the member during and/or following
implantation of the device;
[0092] wherein the substance delivery means comprises a body
defining a chamber and an outlet in communication with the chamber
through which bioactive substance can exit the body and further
wherein the body is relatively slidably mounted to the lead of the
device.
[0093] In a preferred embodiment of this invention, the device is a
cochlear.TM. implant electrode assembly, with the elongate member
adapted to be inserted through a cochleostomy formed in the cochlea
and positioned therein. In this embodiment, the outlet of the
substance delivery means is preferably positionable outside and
adjacent the cochleostomy site. In this embodiment, the body is
preferably relatively slidable along the lead until it reaches a
location along the lead that results in it being positioned just
outside the cochleostomy following implantation.
[0094] In a preferred embodiment, the lead can be provided with a
stop means that prevents the body of the substance delivery means
from being moved relatively past the stop means and onto the
elongate member. In another embodiment, the stop means can comprise
a stop member that, once engaged with the body, prevents subsequent
slidable movement of the collar relative to the lead in either
direction.
[0095] In a preferred embodiment, the elongate member is formed
from a suitable biocompatible material.
[0096] In a further embodiment, the body of the substance delivery
means comprises an annular member that is positioned around the
lead of the stimulating device. The body preferably has an outer
surface. In another embodiment, the annular member can comprise a
cylindrical collar member. In this embodiment, the body preferably
has a longitudinal axis. In one embodiment, the body can be
symmetrical or non-symmetrical about the longitudinal axis.
[0097] In another embodiment, the body can comprise a portion of a
ring, such as a half-pipe.
[0098] The annular member can comprise a first portion and a second
portion, the second portion having an outer diameter less than that
of the first diameter. In one embodiment, both the first portion
and the second portion can be cylindrical. In this case, the outer
surface preferably has a step between the first and second portion.
The outer diameter of the first portion can be about twice that of
the elongate member. In one embodiment, the first portion can have
an outer diameter of about 1.2 mm.
[0099] In yet a further embodiment the body can have a proximal end
and a distal end. The proximal and distal ends can be at least
substantially parallel or parallel.
[0100] In a further embodiment, the outlet of the body can be
positioned in the distal end of the body. In a still further
embodiment, the body can have an inlet in the proximal end of the
body. The inlet and outlet are preferably in communication, such as
fluid communication, with each other.
[0101] In a still further embodiment, the outlet of the body can
comprise an annular opening in the distal end of the body. The
chamber within the body can extend back into the body from the
outlet where the outlet is an annular opening, the chamber can also
be annular in form and so comprise a cylindrical chamber having an
outer and inner surface and extending back into the body from the
outlet.
[0102] In a still former embodiment, the annular chamber has a
region where the outer wall of the chamber moves away from the
longitudinal axis or the lead passing through the body as the
chamber extends back into the body from the outlet. In this
embodiment, the inner wall of the chamber can also move away from
the longitudinal axis or the lead in said region. In one
embodiment, the chamber can have a frusto-conical portion. In yet a
further embodiment, the chamber can comprise a portion distal the
outlet that is also cylindrical in form. In this embodiment, the
inlet preferably comprises a pipe extending from the proximal end
of the body into the chamber. The inlet is preferably adjacent the
outer wall of the body.
[0103] In a still further embodiment, the chamber can comprise a
pipe extending from the proximal end to the distal end of the body.
The pipe is preferably non-linear. In one embodiment, the inlet can
be positioned at least partially further outwardly from the
longitudinal axis of the body relative to the outlet. In this
embodiment, the collar can be non-symmetrical about its
longitudinal axis.
[0104] The distal end of the elongate member is preferably firstly
inserted into the cochleostomy of the implantee during placement of
the implant.
[0105] The chamber in the body can act as a reservoir for a
bioactive substance. In one embodiment, the bioactive substance in
the reservoir can leach from the chamber into the implantee. In one
embodiment, the outlet can have a semi-permeable membrane. The
membrane preferably allows the bioactive substance to leach torn
the chamber during and/or following implantation to the desired
site of action for the bioactive substance.
[0106] Where the bioactive substance is carried in or comprises a
fluid, the semi-permeable membrane preferably allows the fluid to
leach or diffuse therethrough.
[0107] The membrane can act as a valve means that allows fluid
to-exit the chamber but prevents, or at least substantially
prevents, fluid flow from external the chamber back into the
chamber within the body.
[0108] In a further embodiment, the inlet of the body can be in
communication, such as fluid communication, with an additional
reservoir for the bioactive substance that is external or internal
the body of the implantee. A catheter can extend from the inlet to
the additional reservoir. A pump, such as an osmotic pump, can
transfer the bioactive substance from the additional reservoir into
the chamber of the body for subsequent delivery to the appropriate
site of action.
[0109] It is also envisaged that the bioactive substance can be
captured in the form of a solid or semi-solid pellet. In one
embodiment, the pellet can be formed by impregnating the bioactive
substance in a ceramic or a polymer pellet that has a predetermined
rate of release of the bioactive substance. This solid pellet can
then be stored in the chamber or in an external reservoir
connectable to the chamber.
[0110] The device of this aspect may be adapted to only provide
delivery of a bioactive substance to the preferred site for a
particular period following implantation. This period may comprise
any period of time from a few hours or days to a few weeks or even
months. In another embodiment, the device can be used as a means of
delivery of bioactive substances to the implantee well beyond the
time of implantation. For example, the additional reservoir can be
periodically filled with a bioactive substance to ensure continued
supply of the bioactive substance to the implantation site. The
additional reservoir, in this case, may be positioned beneath but
adjacent the surface of the skin of the implantee thereby allowing
the reservoir to be filled by a syringe and needle assembly that
injects the bioactive substance into the additional reservoir.
[0111] According to a thirteenth aspect, the present invention is a
method of delivering at least one bioactive substance to a desired
site of action adjacent a cochleostomy within a patient using a
device as defined in the twelfth aspect, the method comprising the
steps of:
[0112] forming a cochleostomy;
[0113] inserting the elongate member through the cochleostomy;
[0114] closing the cochleostomy; and
[0115] slidably positioning the body of the bioactive substance
delivery means adjacent the cochleostomy and allowing said at least
one bioactive substance to exit therefrom.
[0116] The present invention as defined in each of the above
aspects provides a surgeon with an implantable component that can
be used with a bearing implant electrode array and that can assist
with the delivery of one or more bioactive substances to a position
within the cochlea following implantation of the component. The
substances that can be delivered by the present device include
substances that are adapted to promote healing, substances that
prevent bleeding or at least excessive bleeding, and also
substances that prevent the growth of tissue, including scar
tissue, in the cochlea following implantation. Pharmaceutical
compounds such as anti-inflammatories and antibiotics can also be
delivered by the present device. It is further envisaged that the
bioactive substance may comprise a steroid.
[0117] In a particularly preferred embodiment, the bioactive
substance comprises a neurotrophic factor including neurotrophins,
neuropoietins, insulin-like growth factors, transforming growth
factors beta, fibroblast growth factors and other growth factors
such as transforming growth factor alpha, platelet-derived growth
factor and stem cell factor.
[0118] It is also envisaged that substances that assist in reducing
the resting potential of the surrounding neurons can also be
delivered by the present invention. It should be appreciated that
during neural stimulation the neurons propagate an action potential
through the response of transmembrane ion channels to local
electrical fields. By delivering a substance that elicits a change
in the transmembrane potential, the resting neural membrane
potential can be moved towards the activation potential resulting
in a lowering of the energy required to be delivered to activate
the neuron. This also has the potential to reduce the power
required by the stimulation device as well as increase the
specificity of the electrical stimulation and restore the
stochastic response of the neurons.
[0119] The device of each aspect may deliver bioactive substances
to the preferred site for a particular period following
implantations from a few hours or days to a few weeks or even
months.
[0120] In a further embodiment of the above aspects, the elongate
member of the stimulating device has a plurality of electrodes
mounted thereon. The member can have a diameter of about 0.6 mm.
The member can also have a first configuration selected to allow
said member to be inserted into an implantee's body, such as the
cochlea, and a second configuration wherein said elongate member is
adapted to apply a preselected tissue stimulation with the
electrodes. In a further embodiment, the elongate member can have
at least one intermediate configuration between said first and
second configurations.
[0121] In a still further embodiment of the above aspects, at least
a portion of the outer surface of the elongate member can have a
coating of lubricious material. In a further embodiment, a
substantial portion of the outer surface can have a coating of the
lubricious material. In a still further embodiment, the entire
outer surface of the elongate member can have a coating of the
lubricious material.
[0122] The lubricious material preferably becomes lubricious on
being brought into contact with a fluid, such as a saline solution.
Still further, the coating preferably becomes lubricious on being
brought into contact with a body fluid, such as cochlear fluid.
[0123] In one embodiment, the lubricious material is selected from
the group comprising polyacrylic acid (PAA), polyvinyl alcohol
(PVA), polylactic acid (PLA) and polyglycolic acid (PGA). It is
envisaged that other similar materials could also be used. It is
envisaged that the lubricious material can also be impregnated with
the bioactive substance allowing the coating to perform a dual
role. The rate of delivery of the bioactive substance can be
programmed by design of the coating structure.
[0124] In yet another embodiment, the device can include a
stiffening element made of a second material relatively stiffer
than the resiliently flexible material of the elongate member. The
stiffening element can be adapted to bias the elongate member into
the first configuration.
[0125] In a preferred embodiment, the second configuration of the
elongate member is curved. More preferably, the elongate member
adopts a spiral configuration when in the second configuration.
[0126] The elongate member is preferably preformed from a plastics
material with memory and is preformed to the second configuration.
In a preferred embodiment, the first configuration is preferably
substantially straight. More preferably, the first configuration is
straight.
[0127] In a preferred embodiment, the elongate member is formed
from a suitable biocompatible material. In one embodiment, the
material can be a silicone, such as Silastic MDX 4-4210 or other
biocompatible silicones. In another embodiment the elongate member
can be formed from a polyurethane or similar material.
[0128] In one embodiment, the stiffening element can comprise a
metallic stylet, or a stylet-like element formed from any other
suitable stiffening material, extending through a lumen in the
elongate member. In one embodiment, the wire can be formed from a
biocompatible metal, a biocompatible metallic alloy or a
biocompatible relatively stiff plastic. In a preferred embodiment,
a metal stylet can be formed from platinum.
[0129] Once implanted, the electrodes can receive stimulation
signals from a stimulator device. The stimulator device is
preferably electrically connected to the elongate member by way of
the electrical lead. The lead can include the one or more wires
extending from each electrode of the array mounted on the elongate
member.
[0130] In one embodiment, the lead can extend from the elongate
member to the stimulator device or at least the housing thereof. In
one embodiment, the lead is continuous with no electrical
connectors, at least external the housing of the stimulator means,
required to connect the wires extending from the electrodes to the
stimulator means. One advantage of this arrangement is that there
is no requirement for the surgeon implanting the device to make the
necessary electrical connection between the wires extending from
the electrodes and the stimulator means. In this case, the body of
the substance delivery means is preferably positioned around the
lead prior to attachment of the lead to the stimulator device.
[0131] The stimulator device is preferably positioned within a
housing that is implantable within the implantee. In the
application of the present invention to hearing implants, the
housing for the stimulator device is preferably implantable within
the bony well in the bone behind the ear posterior to the
mastoid.
[0132] When implantable, the housing preferably contains, in
addition to the stimulator device, a receiver device. The receiver
device is preferably adapted to receive Signals from a controller
means. The controller means is, in use, preferably mounted external
to the body of the implantee such that the signals are transmitted
transcutaneously through the implantee.
[0133] Signals can preferably travel from the controller means to
the receiver device and vice versa. The receiver device can include
a receiver coil adapted to receive radio frequency (RF) signals
from a corresponding transmitter coil worn externally of the body.
The radio frequency signals can comprise frequency modulated (FM)
signals. While described as a receiver coil, the receiver coil can
preferably transmit signals to the transmitter coil which receives
the signals.
[0134] The transmitter coil is preferably held in position adjacent
the implanted location of the receiver coil by way of respective
attractive magnets mounted centrally in, or at some other position
relative to, the coils.
[0135] In the application of the present invention to bearing
implants, the external controller can comprise a speech processor
adapted to receive signals output by a microphone. During use, the
microphone is preferably worn on the pinna of the implantee,
however, other suitable locations can be envisaged, such as a lapel
of the implantee's clothing. The speech processor encodes the sound
detected by the microphone into a sequence of electrical stimuli
following given algorithms, such as algorithms already developed
for cochlear.TM. implant systems. The encoded sequence is
transferred to the implanted receiver/stimulator device using the
transmitter and receiver coils. The implanted receiver/stimulator
device demodulates the FM signals and allocates the electrical
poises to the appropriate attached electrode by an algorithm which
is consistent with the chosen speech coding strategy.
[0136] For other applications beyond hearing implants, the external
controller can comprise a simple electronic unit capable of being
programmed to perform a specific task, such as a predetermined
stimulation pattern to a region of the brain or nerves in
accordance with a trigger event, such as a sensed body condition or
a patient-triggered action.
[0137] The external controller further comprises a power supply.
The power supply can comprise one or more rechargeable batteries.
The transmitter and receiver coils are used to provide power via
transcutaneous induction to the implanted receiver/stimulator
device and the electrode array.
BRIEF DESCRIPTION OF THE DRAWINGS
[0138] By way of example only, a preferred embodiment of the
invention is now described with reference to the accompanying
drawings, in which:
[0139] FIG. 1 is a pictorial representation of a prior art hearing
implant system;
[0140] FIG. 2 is a simplified view of one embodiment of an elongate
member according to one aspect of the present invention;
[0141] FIG. 3 is a simplified view of another embodiment of an
elongate member according to the present invention;
[0142] FIG. 4 is a simplified view of still another embodiment of
an elongate member according to the present invention;
[0143] FIGS. 5a and 5b are simplified views of yet another
embodiment of an elongate member according to the present
invention;
[0144] FIGS. 6a and 6b are simplified views of yet still another
embodiment of an elongate member according to the present
invention;
[0145] FIGS. 7a, 7b and 7c are views of different types of pores
according to the present invention;
[0146] FIG. 8 depicts one type of porous structure for use in one
aspect of the present invention;
[0147] FIG. 9 depicts another type of porous structure for use in
the present invention;
[0148] FIG. 10a is a simplified enlarged view of one embodiment of
a prior art electrode assembly;
[0149] FIG. 10b is a cross-sectional view of the device of FIG.
10a;
[0150] FIG. 11 is a simplified view of an electrode assembly
according to another aspect of the present invention;
[0151] FIGS. 11a-11c are cross-sectional views of another
embodiment of an electrode assembly according to this further
aspect of the present invention;
[0152] FIG. 12 is a simplified view of another embodiment of an
electrode assembly according to the further aspect of the present
invention;
[0153] FIG. 13 is a simplified view of a still further embodiment
of an electrode assembly according to this aspect of the present
invention;
[0154] FIG. 14 is a simplified view of a still further embodiment
of an electrode assembly according to this aspect of the present
invention;
[0155] FIG. 15 is a simplified view of a still further embodiment
of an electrode assembly according to this aspect of the present
invention;
[0156] FIGS. 16a-16c are cross-sectional views of an electrode
assembly according to this aspect of the present invention;
[0157] FIG. 17 is a simplified view of a still further embodiment
of an electrode assembly according to this further aspect of the
present invention;
[0158] FIG. 18 is a simplified view of a further embodiment of an
electrode assembly according to this aspect of the present
invention;
[0159] FIG. 19 is a simplified cross-sectional view of one
embodiment of an electrode assembly according to another further
aspect of the present invention;
[0160] FIG. 19a is a cross-sectional view of the device of FIG. 19
through line AA;
[0161] FIG. 19b is a cross-sectional view of the device of FIG. 19
through line BB;
[0162] FIG. 20 is simplified cross-sectional view of another
embodiment of a device according to this further aspect of the
present invention;
[0163] FIG. 20a is a cross-sectional view of the device of FIG. 20
through line AA; and
[0164] FIG. 20b is a cross-sectional view of the device of FIG. 20
through line BB.
PREFERRED MODE OF CARRYING OUT THE INVENTION
[0165] Before describing the features of the present invention, it
is appropriate to briefly describe the construction of one type of
known hearing implant system with reference to FIG. 1.
[0166] Known bearing implants typically consist of two main
components, an external component including a speech processor 29,
and an internal component including an implanted receiver and
stimulator unit 22. The external component includes a microphone
27. The speech processor 29 is, in this illustration, constructed
and arranged so that it can fit behind the outer ear 11.
Alternative versions may be worn on the body. Attached to the
speech processor 29 is a transmitter coil 24 which transmits
electrical signals to the implanted unit 22 via a radio frequency
(RF) link.
[0167] The implanted component includes a receiver coil 23 for
receiving power and data from the transmitter coil 24. A lead 21
extends from the implanted receiver and stimulator unit 22 to the
cochlea 12 and terminates in an electrode array 20 that is passed
through a cochleostomy and into the cochlea 12. The signals thus
received are applied by the array 20 to the basilar membrane 8 and
the nerve cells within the cochlea 12 thereby stimulating the
auditory nerve 9. The operation of such a device is described, for
example, in U.S. Pat. No. 4,532,930, the contents of which are
incorporated herein by reference.
[0168] The array 20 typically comprises an elongate electrode
carrier member having a plurality of electrodes mounted thereon.
The elongate member is also typically preformed from a resiliently
flexible silicone with memory and can be preformed to a curved
configuration suitable for insertion in the scala tympani of a
human cochlea 12. While an assembly that normally adopts a curved
configuration when in a relaxed condition is typically preferred,
it will be appreciated that the present invention also could be
utilised with respect to assemblies that are normally straight when
in a relaxed condition.
[0169] Still further, the array 20 typically has a lumen that,
prior to insertion of the assembly 20 into the cochlea 12, can
receive a substantially straight platinum stylet. Such a stylet
typically has a stiffness that is sufficient to retain the silicone
elongate member in a straight configuration.
[0170] As depicted, the electrode assembly 20 has an electrical
lead 21 extending hack to a receiver/stimulator unit 22. In
considering this invention, it is to be understood that each
electrode may have one or more wires electrically connected thereto
and extending from each respective electrode 32 back through the
lead 21 to the receiver/stimulator unit 22.
[0171] Various, examples of elongate members according to one
aspect of the present invention are depicted in FIGS. 2 to 6b.
Where electrodes are depicted in these drawings, it is to be
understood that the electrodes are not necessarily shown to scale.
A larger number of electrodes than that depicted can also be
envisaged.
[0172] FIG. 2 depicts an elongate member 49 having a plurality of
electrodes 41 which are formed from a biocompatible porous platinum
material. In the depicted embodiment, each of the electrodes 41 are
formed from this material and each adapted to deliver electrical
stimulation to the cochlea following implantation. It will be
appreciated that in another embodiment, only some of the electrodes
41 may be formed from the porous platinum material, with some of
the electrodes being fanned from a suitable relatively non-porous
metallic material, such as platinum as traditionally used in
cochlear.TM. implant electrode arrays. In this embodiment, the
electrodes 41 have a bioactive substance disposed within the pores
of the platinum material that is able to migrate front the
electrodes 41 following implantation of the member 40.
[0173] FIG. 3 depicts another embodiment of an elongate member 50
again having a plurality of electrodes 41 which are formed from a
biocompatible porous platinum material. In this embodiment,
however, the elongate member is provided with a further set of
porous platinum rings 51 that are mounted to the member. As
depicted, the rings 51 can be disposed between the electrodes 41
mounted on the member Other locations for the rings can be
envisaged. In this embodiment, the rings 51, unlike the electrodes
41, are not adapted to deliver electrical stimulation to the
auditory system 12, rather, the electrodes are electrically active
but are adapted to create an electrical field to release a drag
from the member. If they are electrically active then they can be
considered to be electrically stimulating the cochlea but not
necessarily delivering auditory stimuli thereto. Like the
electrodes 41, the depicted rings 51 have a bioactive substance
disposed within the pores of the platinum material that is able to
migrate from the rings 51 following implantation of the member 50.
In a further example, rings 51 may not deliver electrical
stimulation to the auditory system immediately after implantation
and then role is limited to release of drugs. Once the supply of
drugs has been exhausted, the rings 51 revert to delivering
electrical stimulation to the auditory system.
[0174] The electrical field required for the release of drugs may
be created by stimulation in monopolar, bipolar, tripolar, etc
mode.
[0175] In a further example, the stimulating electrodes are
different from the drug delivering electrodes in either shape
and/or in electrical connection.
[0176] While FIG. 3 depicts the rings 51 mourned on a member in
conjunction with porous platinum electrodes 41, the rings could
instead be mounted on an elongate member where some or all of the
electrodes are formed from a relatively non-porous platinum as is
traditionally used in hearing implant electrode arrays.
[0177] FIG. 4 depicts a still further embodiment of an elongate
member 60 in which the material forming the body 61 of the member
to which the electrodes 62 are mounted is formed of porous
material, such as a porous silicone. The pores of the body 61 have
a bioactive substance disposed therein that is able to migrate from
the body 61 following implantation of the member 60.
[0178] While the depicted electrodes 62 are traditional relatively
non-porous electrodes, it will be appreciated that one, some or all
of the electrodes 62 could be formed from a porous material, such
as a porous platinum.
[0179] FIG. 4 also depicts the entire body 61 as being formed from
a porous material. In another embodiment, it will be appreciated
that only one or more portions of the body 61 could be formed of
such a material.
[0180] Where the body 61 is comprised of more than one portion,
each of the portions can comprise the same material as the
remainder of the elongate member hut having a plurality of pores
disposed therethrough. In one embodiment, the porous portions can
comprise the same material as the remainder of the elongate member
but which has undergone a processing step to render the portions
foraminous.
[0181] In another embodiment, the porous portions of the body 61
can be formed from a different material to that of the remainder of
the elongate member.
[0182] FIGS. 6a and 6b depict a surface of an elongate member 71
that is surrounded by a sheath 72 fabricated from a porous
material. As depicted, a quantity of bioactive substance 73 can be
disposed beneath the sheath 72 and is free to migrate through the
pores 74 in the sheath 72 in the direction of arrows A. In this
embodiment, it will be appreciated that the elongate member 71
could have one or more of the features of the other elongate
members described herein including those depicted in FIGS. 2-4.
[0183] In each of the embodiments, each pore 81 of the porous
material can be an individual pore within the portion, making no
interconnection with another pore in the portion such as is
depicted in FIG. 8. In FIG. 8, each of the pores 81 are aligned and
equally spaced with respect to each other.
[0184] As depicted in FIG. 9, the porosity cars be in essence in
three dimensions with some or all of the pores 91 in a porous
portion being interconnected in some way.
[0185] In some or each of the porous portions, at least some of the
pores or each pore of the porous portion can be at least
substantially uniform in cross-sectional shape relative to each
other. In another embodiment, the pores can vary in cross-sectional
shape from one to at least some of the others.
[0186] In some or each of the porous portions, at least some of the
pores or each pore of the porous portion can be substantially
uniform in diameter. In another embodiment, the pores can vary in
diameter from one to at least some of the others.
[0187] In some or each of the porous portions, at least some of the
pores or each pore of the porous portion can be of a substantially
constant diameter along its length. In another embodiment, at least
some of the pores or each pore cart vary in diameter along its
length.
[0188] In some or each of the porous portions, at least some of the
pores or each pore of the porous portion can have a substantially
uniform cross-sectional shape along its length. In another
embodiment, at least some of the pores or each pore can vary in
cross-sectional shape along its length.
[0189] In some or each of the porous portions, at least some of the
pores or each pore of the porous portion can be of a substantially
constant length. In another embodiment, at least some of the pores
or each pore can vary in length relative to at least some of the
others in that portion. In one embodiment, at least some of the
pores can have relatively extended lengths compared to other pores
in that portion.
[0190] In some or each of the porous portions, at least some of the
pores or each pores of the porous portion can be at least
substantially linear, such as respective pores 100 and 101 depicted
in FIG. 7a and 7b. In another embodiment, at least some of the
pores or each pores of the porous portion can be non-linear such as
pore 102 depicted in FIG. 7c.
[0191] In some or each of the porous portions, at least some of the
porous portions or each porous portion can have substantially the
same of pores per unit area. In another embodiment, at least some
of the porous portions or each porous portion can have differing
number of pores per unit area relative to that of at least some of
the other porous portions.
[0192] In some or each of the porous portions, at least some of the
pores in one, some or each of the porous portions can have
relatively smooth internal walls, such as pore 100 depicted in FIG.
7a. In another embodiment, at least some of the pores to one, some
or each of the porous portions can have rippled internal walls,
such as pore 101 depicted in FIG. 7b. The ripples can have a
suitably small dimension to preferably at least substantially
prevent wetting of the cavities thereby minimising friction between
the bioactive substance and the walls.
[0193] The nature of the porosity between separate porous portions
of the device may be the same or vary from one to at least some or
all of the other portions. For example, the dimension of the pores
of a porous portion relatively close to the distal end of the
elongate member may be different to the dimensions of the pores of
a porous portion that is relatively close to the proximal end of
the elongate member. In this embodiment, the portion relatively
closer to the distal end can have pores having a diameter and/or
length greater than the pores of the porous portion relatively
closer to the proximal end of the elongate member. In another
embodiment, the relative porosity of different portions can be
essentially random.
[0194] In some or each of the porous portions, at least some of the
pores of the porous portion can be preferably adapted to be at
least substantially closed when the elongate member is at least
substantially straight thereby preventing migration of any
bioactive substance held within said at least some pores from these
pores. See for example FIG. 5a which depicts pores 103 as adopting
a closed configuration when the elongate member is straight. On
adopting a curved configuration, the pores 103 are adapted to at
least partially open allowing migration of the bioactive substance
therefrom, as represented by arrows B.
[0195] In this invention, the bioactive substances can be free to
simply migrate from the pores of the porous portions following
implantation of the device. In another embodiment, the bioactive
substance can be dispersed in an some fluid that is preferably
caused to migrate from the pores on application of a suitable
electrical field thereto. In another embodiment, the bioactive
substance can be dispersed in an ionic solution that is allowed to
diffuse from the pores and/or be expelled therefrom under
application of a suitable electric field.
[0196] In one embodiment the bioactive substance can be dispersed
in a suitable fluid, In one embodiment, the bioactive substance can
comprise a steroid. In another embodiment, the bioactive substance
can perform a function of reducing the resting neuron potential of
neurons within the cochlea. The use of such substances can result
in less energy being required to excite the neurons and cause
stimulation.
[0197] In the present invention, the at least one bioactive
substance can be delivered to a desired site of action within a
cochlea using a device as described herein. The method preferably
comprises the steps of:
[0198] forming a cochleostomy;
[0199] inserting the elongate member as described herein through
the cochleostomy;
[0200] allowing or causing the bioactive substance to migrate from
the elongate member into the cochlea.
[0201] In this method, the pores of the device are at least
partially filled by dipping the elongate member in the bioactive
substance for a suitable time period. This step can be performed
immediately after manufacture of die elongate member. In another
embodiment, the step can be performed just prior to implantation of
the member into the implantee.
[0202] FIG. 10a shows a prior art array 120 comprising an elongate
electrode carrier member 131 having a plurality of electrodes 132
mounted thereon.
[0203] As depicted in FIG. 10b, the array 120 typically has a lumen
134 that, prior to insertion of the assembly 120 into the cochlea,
can receive a substantially straight platinum stylet. Such a stylet
typically has a stiffness that is sufficient to retain the silicone
elongate member 131 in a straight configuration.
[0204] A resiliency flexible elongate member according to a further
aspect of the present invention is depicted generally as 140 in
FIGS. 11 and 11a. The member 140 has a plurality of electrodes 132
mounted thereon for delivering electrical stimulation to the
cochlea.
[0205] Within the member 140 is at least a partially encapsulated
member 141 of biocompatible material that has been impregnated with
at least one bioactive substance. In this embodiment depicted in
FIG. 11, the member extends tor at least a majority of the length
of the elongate member and is of a substantially constant diameter
along its length.
[0206] As can be determined from a comparison of FIGS. 11a and 11b,
the cross-sectional shape of the member 141 can vary from one array
to the next. Also, in another embodiment as depicted in FIG. 11c,
the member 142 can be inserted through the lumen 134 used by the
stylet during implantation of the array in the cochlea of an
implantee.
[0207] As depicted in FIGS. 12 and 13, the member 141 can vary in
diameter along its length. For example, as depicted in FIG. 12, the
diameter of the member 141 can gradually taper from the proximal
end towards the distal end of the elongate member 140. In FIG. 13,
the diameter decreases in a step-wise fashion front the proximal
end towards the distal end.
[0208] FIG. 14 depicts a still further embodiment where an
impregnated plug-like member 142 extends into the elongate member
140 from the distal end thereof.
[0209] One or more openings can be provided in the elongate member
140 to allow bioactive substances in the member 141 or 142 to
diffuse from the member and exit the elongate member. Openings can
be provided at various locations along the member, including the
distal end 143 of the elongate member. Arrows A depict possible
locations of diffused bioactive substance into the cochlea.
[0210] There can instead or also be one or more openings at a
location spaced from the distal end 143. Where there is more than
opening, the openings can be regularly or irregularly spaced along
the elongate member.
[0211] As is depicted in FIGS. 15 to 18, the elongate member can
have impregnated members disposed in the outer face of the elongate
member.
[0212] As depleted in FIGS. 16a, 16b and 16c, the impregnated
members can comprise a ring member 160 (FIG. 16a) of a half-ring
member 161 (FIG. 16b) disposed in the outer face of the elongate
member. In another embodiment, the impregnated member can comprise
a number of portions 162 that are disposed along the locus of a
ring formed in the outer surface of the elongate member (see FIG.
16c).
[0213] FIG. 15 depicts how a plurality of rings 160 can be disposed
between the electrodes 132 of the array. It will be appreciated
that the rings 160 of FIG. 15 could be replaced in one, some, or
all instances, by half-rings 161 or ring portions 162. In the
depicted embodiment, the ring members 160 stand inst proud of the
outer surface of the elongate member. It will be appreciated that
one or more of the ring members etc could be at least substantially
flush with the outer surface of the elongate member or be recessed
in the elongate member.
[0214] As depicted in FIG. 17, impregnated portions 170 can be
disposed around the electrodes 132 mounted in the elongate member.
Where the electrode comprises a ring or ring portion, the portion
can comprise an annular or part-annular member that surrounds the
electrode 132.
[0215] As depicted in FIG. 18, the electrode 132 can be disposed
around an impregnated portion 180 of biocompatible polymeric
material.
[0216] One embodiment of a further aspect of a hearing implant
electrode assembly incorporating a system for delivery of bioactive
substances is depicted generally as 230 in FIG. 19.
[0217] The assembly 230 includes an elongate member 231 that has a
distal end 233 that is firstly inserted into the cochlea upon
insertion of the assembly 230.
[0218] As depicted in FIG. 19, a collar 240 is slidably disposed
around the lead 21. The collar 240 is part of a system for
delivering one or more pharmaceutical or bioactive substances to a
location just external the cochleostomy of the cochlea.
[0219] In FIG. 19, the collar 240 can be moved along the lead 21
towards the distal end 233 of the array member until it reaches a
stop member that prevents further slidable movement of the collar
in that direction.
[0220] The collar 240 has a stepped outer surface 241 defined by
two cylindrical portions 242 and 243. In the depicted embodiment,
the collar 240 is symmetrical about its longitudinal axis and has
parallel proximal and distal ends 244,245.
[0221] The outlet 246 of the collar 240 is positioned in the distal
end 245 of the collar 240. In the depicted embodiment, the collar
240 further has an inlet 250 in the proximal end 244 of the collar
240. The inlet and outlet are in communication, such as fluid
communication, with each other.
[0222] As depicted in FIG. 19, the outlet 246 of the collar 240
comprises an annular opening in the distal end 245 of the collar.
The chamber 247 within the collar extends back into the collar 240
from the outlet 246. As the depicted outlet 246 is an annular
opening, the chamber 247 is also annular in form and so comprises a
cylindrical chamber having an outer and inner surface and extending
back into the collar from the outlet 246. It will be appreciated,
however, that the outlet and chamber need not be annular to fall
within the scope of the present application.
[0223] The annular chamber 247 has a frusto-conical region 248
where the outer and inner walls of the chamber 247 move away from
the longitudinal axis of the collar 240, and a further cylindrical
region 249 distal the outlet. In this embodiment, the inlet 250
comprises a pipe extending from the proximal end 244 of the collar
into the chamber 247. The inlet 250 is adjacent the outer wall 241
of the collar 240.
[0224] A different construction of a collar is generally depicted
as 260 in FIGS. 20, 20a and 20b. As depicted, the chamber can
instead comprise a non-linear pipe 261 extending from the proximal
end 244 to the distal end 245 of the collar 260. The inlet 250 is
positioned at least partially further outwardly from the
longitudinal axis of the collar 260 body relative to the outlet
246.
[0225] The distal end 233 of the elongate member is preferably
firstly inserted into the cochleostomy of the implantee during
placement of the implant.
[0226] The chamber in the collar acts as a reservoir for a
bioactive substance. This bioactive substance in the chamber
diffuses from the chamber into the implantee through a
semi-permeable membrane 270 in the outlet 246. The membrane 270
allows the bioactive substance to leach from the chamber during
and/or following implantation to the desired site of action for the
bioactive substance.
[0227] Where the bioactive substance is carried in or comprises a
fluid, the semi-permeable membrane 270 allows the fluid to leach or
diffuse therethrough.
[0228] The membrane 270 can act as a valve means that allows fluid
to exit the chamber but prevents, or at least substantially
prevents, fluid flow from external the chamber back into the
chamber within the body.
[0229] A catheter 280 can extend from the inlet 250 to an
additional reservoir for a bioactive substance. A pump, such as an
osmotic pump, can transfer the bioactive substance from the
additional reservoir into the chamber of the body for subsequent
delivery to the appropriate site of action.
[0230] It is also envisaged that the bioactive substance can be
captured in the form of a solid or semi-solid pellet. In one
embodiment, the pellet can be formed by impregnating the bioactive
substance in a ceramic or a polymer pellet that has a predetermined
rate of release of the bioactive substance. This solid pellet can
then be stored in the chamber or in an external reservoir
connectable to the chamber.
[0231] The provision of a system for delivering a pharmaceutical
substance in the cochlea that promotes healing and/or more
efficient neural stimulation while preventing the formation of
substantial scar tissue in the cochlea, enhances the likelihood of
successful long-term placement of the elongate member in the
cochlea and subsequent successful use of the hearing implant by the
implantee.
[0232] While the preferred embodiment of the invention has been
described in conjunction with a hearing implant. It is to be
understood that the present invention has wider application to
other implantable electrodes, such as electrodes used with
pacemakers.
[0233] 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.
* * * * *