U.S. patent application number 12/556720 was filed with the patent office on 2010-03-11 for implantable electrode array assembly with extraction sleeve/tether.
Invention is credited to Richard F. Huyser, John J. Janik, Douglas A. Staunton.
Application Number | 20100063568 12/556720 |
Document ID | / |
Family ID | 41799909 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100063568 |
Kind Code |
A1 |
Staunton; Douglas A. ; et
al. |
March 11, 2010 |
IMPLANTABLE ELECTRODE ARRAY ASSEMBLY WITH EXTRACTION
SLEEVE/TETHER
Abstract
An implantable electrode array including a carrier on which
plural electrodes are disposed. Also disposed on the carrier is an
array antenna over which signals are wirelessly received. A tether
is connected to the carrier. A tether antenna is attached to the
tether. After the electrode array is implanted, during a trial
period instructions and power are transmitted to the array antenna
over the tether antenna. If the trial is successful, the tether is
disconnected from the electrode array. If the trial is not
successful and extraction of the array is necessary, extraction is
accomplished by pulling on the tether. Electrode array removal may
be facilitated by the pulling of the array into an extraction tube
disposed over the tether.
Inventors: |
Staunton; Douglas A.; (Texas
Township, MI) ; Janik; John J.; (Hudsonville, MI)
; Huyser; Richard F.; (Kalamazoo, MI) |
Correspondence
Address: |
INTEL. PROP./ RND;STRYKER CORPORATION
4100 EAST MILHAM AVE.
KALMAZOO
MI
49001-6197
US
|
Family ID: |
41799909 |
Appl. No.: |
12/556720 |
Filed: |
September 10, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61096196 |
Sep 11, 2008 |
|
|
|
Current U.S.
Class: |
607/116 |
Current CPC
Class: |
A61N 1/3787 20130101;
A61N 1/36071 20130101; A61N 1/0551 20130101; A61N 1/37217
20130101 |
Class at
Publication: |
607/116 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1. An implantable electrode array assembly, said assembly
including: a carrier; a plurality of electrodes disposed on said
carrier, said electrodes designed to flow current through tissue;
an array antenna disposed on said carrier for wirelessly receiving
signals; a control circuit disposed on said carrier, said control
circuit connected to said electrodes and said antenna, said control
circuit configured to receive signals from said antenna and, based
on the received signals, cause current to be selectively sourced
from at least one said electrode and sunk into at least one said
electrode; and a tether connected to said carrier, said tether
including a tether antenna over which signals are wirelessly
transmitted to said array antenna.
2. The implantable electrode array assembly of claim 1, wherein
said tether is in the form of a sleeve that is disposed over said
array antenna and said tether antenna is attached to said sleeve so
as to extend at least partially over said array antenna.
3. The implantable electrode array assembly of claim 1, wherein:
said tether is a substrate that is attached to said carrier so as
to at least partially subtend over or under said array antenna; and
said tether antenna is disposed on said tether substrate so as to
be on a portion of said substrate that subtends said array
antenna.
4. The implantable electrode array assembly of claim 1, wherein a
wire extends through said tether and at least partially through
said carrier so as to connect said tether to said carrier, and said
wire is at least partially retractable through said tether so that
the retraction of said wire disconnects said wire and said tether
from said carrier.
5. The implantable electrode array assembly of claim 4, wherein
said wire is said tether antenna.
6. The implantable electrode array assembly of claim 1, wherein at
least one flexible web connects said tether to said carrier.
7. A method of implanting an electrode array against tissue, said
method including the steps of implanting an electrode array against
the tissue, the array including: a carrier; a plurality of
electrodes disposed on said carrier, said electrodes designed to
flow current through tissue; an array antenna disposed on said
carrier for wirelessly receiving signals; a control circuit
disposed on said carrier, said control circuit connected to said
electrodes and said antenna, said control circuit configured to
receive signals from said antenna and, based on the received
signals, cause current to be selectively sourced from at least one
said electrode and sunk into at least one said electrode; and a
tether connected to said carrier, said tether including an a tether
antenna over which signals are wirelessly transmitted to said array
antenna; transmitting signals over the tether antenna to the array
antenna so as to cause current to flow between the electrodes that
results in current flow through the tissue; evaluating whether or
not the current flow through the tissue provides a beneficial
therapy; if the current flow through the tissue does not provide
beneficial therapy, pulling on the tether to extract the electrode
array from the tissue; if the current flow through the tissue
provides beneficial therapy, disconnecting the tether from the
carrier and withdrawing the carrier away from the tissue; and
wirelessly transmitting signals to the array antenna through an
antenna other than the tether antenna that results in the continued
current flow between the electrodes.
8. The method of implanting an electrode array of claim 7, wherein:
the tether is connected to the array carrier by a web; and said
step of disconnecting the tether from the array carrier includes
the step of severing the web that extends between the carrier and
the tether.
9. The method of implanting an electrode array of claim 7, wherein:
the tether is connected to the carrier by a wire; and said step of
disconnecting the tether from the array carrier includes the step
of at least partially withdrawing the wire from the tether so that
said withdrawal of the wire results in the disconnection of the
wire from the array carrier.
10. The method of implanting an electrode array of claim 9, wherein
in said step of transmitting signals over the tether antenna to the
array antenna, the wire that connects the tether to the array
carrier functions as the tether antenna.
11. The method of implanting an electrode array of claim 7, wherein
said step of evaluating whether or not the current flow through the
tissue provides a beneficial therapy includes the step of
evaluating whether or not the side effects of the current flow are
tolerable.
12. The method of implanting an electrode array of claim 7,
wherein: the array carrier has a width; and as part of said
extraction step, the electrode array is pulled into an extraction
tube, the extraction tube having a lumen small than the width of
the array carrier and during said pulling of the electrode array
into the extraction sleeve, the array carrier is folded into the
extraction tube lumen.
Description
RELATIONSHIP TO EARLIER FILED APPLICATION
[0001] This application claims priority from U.S. Provisional
Patent App. No. 61/096,196 filed 11 Sep. 2008 the contents of which
are explicitly incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to a wirelessly powered and
controlled electrode array assembly that can be implanted
percutaneously. More particularly, this invention relates to such
an electrode array assembly with an extraction device that
facilitates the post-implantation removal of the array.
BACKGROUND OF THE INVENTION
[0003] A number of different medical therapies involve the
placement of plural electrodes against tissue located in the body.
One such therapy in which positioning of such electrodes is
sometimes performed is pain management therapy. Pain management
therapy may be necessary when an individual, due to injury or
disease, is in a chronic pain state. If little can be done about
the source of the pain, an individual may have to live with the
chronic feeling of pain. Pain management therapy may also be
appropriate when an individual suffers a naturopathic injury or
illness. An example of such an injury is when nerve impingement
results in nerve damage. A damaged nerve may be the source of pain
signals perceived as an ongoing trauma to a region of the body
distal to the nerve. A nerve injury may be perceived as a burning
sensation.
[0004] Pain signals are transferred through the individual's
nervous system. More particularly, a pain signal is typically
generated by a nerve associated with the tissue that is subject to
injury, inflammation or other pain-causing event. The pain signal
is transmitted from this local nerve to a network of neurons
residing in the spinal cord. The neurons internal to the spinal
cord function as the path through which the pain signal is then
transmitted to a specific region of the brain. The receipt of the
signal by the brain is perceived by the individual as an indication
that a particular tissue or organ is in some sort of distress.
[0005] Some pain management therapies involve the use of drugs.
Certain drugs, for example, interrupt the transmission of the pain
signals to the brain. Unfortunately, many of these drugs are
globally transmitted through the body via the circulatory system.
As a consequence, a drug can produce undesirable systemic effects
that may impede the ability of the individual to perform tasks that
require constant neural input; driving or machinery operation for
example. Some drugs can be administered to a specific site on the
body. These drugs only interrupt the transmission of pain signals
from a specific location. This type of therapy offers advantages
over therapy in which a drug is introduced throughout the body.
[0006] To maintain pain relief over a long time period,
site-specific drugs are often administrated through portable
devices that a patient can wear. A disadvantage of this type of
therapy is that an individual may find it difficult to wear this
type of device for an extended period of time. It is also known to
administer a site-specific drug using a pump implanted in the
patient. While these pumps are useful, there are some difficulties
associated in refilling them.
[0007] An alternative to these therapies is to apply electrical
signals to the neural network to counteract the chronic
transmission of pain signals. One such therapy involves applying
these signals from the epidural space through the dura, the outer
covering of the spinal cord, to the nerves forming the dorsal
columns of the spinal cord. These columns are located on the dorsal
side of the spinal cord. The signals are applied to this portion of
the spinal cord because both studies and practice show that, when
the nerves in this portion of the spinal cord are stimulated with
electrical signals, there is an appreciable masking of the
perception of pain.
[0008] An advantage of using this electrical stimulus to mask pain
signals is that it can be site specific. The control of signals
using this type of therapy can often be adjusted so that it does
not interfere with the reception or transmission of other
neurological signals to or from the brain. Consequently, the
masking of the pain signals using this type of therapy does not,
for many individuals, impede their abilities to perform daily
living tasks.
[0009] A number of different electrode array assemblies have been
developed that are designed for implantation against the spinal
dura. A typical assembly includes multiple individual spaced apart
electrodes. Some of these assemblies include a substrate that
supports an array of plural rows and columns of individual
electrodes. The electrode assembly itself includes a number of
longitudinally spaced apart electrodes. Once the electrode assembly
is positioned adjacent the dura, current pulses are applied between
selected sets of electrodes. These current pulses flow, in part,
through the spinal cord. The electrode current flow patterns are
experimented with until the individual reports, instead of pain, a
more tolerable tingling sensation. This tingling sensation is known
as paresthesia.
[0010] The Applicants' Assignee's PCT Pat. App. No.
PCT/US2009/033769 filed 11 Feb. 2009, the contents of which is
explicitly incorporated herein by reference, and are contained in
PCT Pub. Ser. No. ______, also incorporated herein by reference,
discloses one electrode array assembly with plural rows and columns
of electrodes. The assembly of this invention includes a substrate
formed from superelastic material. An advantage of this assembly is
that it can be folded into an insertion cannula that is smaller in
width than the width of the array itself. The cannula is inserted
percutaneously through the skin between vertebra and in the
epidural space above the dura. Upon deployment from the cannula,
the electrode array assembly unfolds over the dura. An advantage of
this invention is that it eliminates the need to make a major
incision in the patient and perform a laminectomy or a laminotomy
to position the electrode array assembly over the dura.
[0011] Electrical stimulation of neural tissue to foster pain
relief, sometimes called neuromodulation, is an effective therapy.
Nevertheless, like all therapies, success is not guaranteed.
Accordingly, presently it is a common practice to initially implant
a test electrode array assembly in a patient prior to the
implantation of a permanent electrode array assembly. The test
electrode array assembly is in the form of a cylinder. After the
test assembly is implanted, signals are sourced to the electrodes
on the assembly from a source through conductors on the assembly
that project out of the patient. The patient's response to the flow
of current between the electrodes of the test assembly is
monitored, often for several days. Owing to its small size and
circular shape, once this analysis is performed, the test assembly
can be removed relatively easily.
[0012] Ideally, the test results indicate there is a significant
likelihood that the patient will benefit from the implantation of a
permanent electrode array assembly. However, there is always a
chance that the patient did not obtain appreciable relief when the
test assembly was activated. This information indicates to the
patient and the practitioner that patient may not gain relief if a
permanent electrode array assembly is implanted against his/her
dura.
[0013] The above process reduces the likelihood that an individual
is subjected to the expense, and trauma of having a permanent
electrode array assembly and complementary pulse generator
implanted when there is not a significant likelihood the procedure
will offer significant relief.
[0014] However, in the event activation of the test array indicates
that the patient could benefit from the permanent electrode array,
the patient must then be subjected to the trauma of a second
procedure to implant the array.
[0015] Further, it should be understood that, when the permanent
electrode array is implanted, there is no guarantee that its
electrodes will be in the same location at which the electrodes of
the test assembly were located. Consequently, even though the
results with the test array indicated the patient would benefit
from such therapy, the results, due to the placement of the
permanent array, may yield less than desirable results.
SUMMARY OF THE INVENTION
[0016] This invention is directed to a new and useful electrode
array assembly adapted for implantation against or within living
tissue. The electrode array assembly of this invention includes a
carrier on which plural spaced-apart electrodes are arranged in
rows and columns. The assembly of this invention also includes an
extraction sleeve or tether. A disconnectable connecting member
attaches the extraction sleeve/tether to the carrier.
[0017] In some versions of this invention, also attached to the
carrier is an antenna. The antenna receives signals that supply
energy for applying the current to the electrodes. The signals also
often include the instructions that indicate between which
electrodes the current is to be flowed. In these versions of the
invention, a complementary antenna is disposed in the
sleeve/tether. In some embodiments of this version of the
invention, when the electrode array assembly is initially deployed,
the assembly carrier is disposed in the extraction sleeve.
[0018] After the electrode assembly of this invention is initially
deployed, the sleeve/tether remains attached to the assembly.
Often, the sleeve is allowed to extend outside of the body. Signals
are applied to the electrodes to cause currents to flow through the
tissue located between different combinations of electrodes. These
currents are flowed to determine if this activity results in the
desired therapeutic effect with, ideally, tolerable side effects.
At this time the assembly can be considered to be in a trial state.
This trial period can last for several days.
[0019] As a result of the trial use of the assembly, it may be
determined that the assembly is able to provide the desired therapy
with acceptable side effects. In this situation, a severing tool,
also part of this invention, is employed to disconnect the
extraction tether from the electrode assembly. The sleeve is the
removed from the patient. At this time the assembly is considered
to be permanently implanted.
[0020] During the trial period, it may become apparent that the
assembly does not provide the desired end result or that the side
effects of the therapy are not tolerable. In these circumstances,
the assembly is then removed from the patient. This step is
performed by withdrawing the extraction sleeve/tether so as to
result in the like withdrawal of the electrode array assembly from
the tissue against which it is mounted and out of the patient.
[0021] The electrode array assembly of this invention is thus
designed to be withdrawn from the patient if it cannot provide a
benefit or, if it is able to so provide a benefit, to be left in
the patient. Implantation of this assembly thus avoids having to
subject an individual to the trauma associated with having to first
implant and then remove a trial assembly. Moreover, the same
electrode array assembly serves as both the trial and permanent
implant. Accordingly, the potential problems with the imprecise
positioning of permanent electrode array after the trial array is
removed are eliminated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention is pointed out with particularity in the
claims. The above and further features and advantages of this
invention are understood from the following Detailed Description in
combination with the accompanying drawings in which:
[0023] FIG. 1 is a plan view of an electrode array assembly of this
invention;
[0024] FIG. 2 is a sectional view showing the electrode array
disposed over tissue, the specific tissue being the dura of the
spinal cord;
[0025] FIG. 3 is a longitudinal view of the electrode array
assembly of this invention disposed over the spinal dura;
[0026] FIG. 4 is a cross sectional view of the electrode array
assembly;
[0027] FIG. 5 is a plan view of the carrier on which the electrode
array assembly is formed;
[0028] FIG. 6 is a side and partial cross sectional view of the
electrode array assembly disposed in an extraction sleeve;
[0029] FIG. 7 is a lateral cross sectional view of the electrode
array assembly taken along line 7-7 of FIG. 6;
[0030] FIG. 8 is a lateral cross sectional view of the electrode
array assembly taken along line 8-8 of FIG. 6;
[0031] FIG. 9 is a side and partial cross sectional view of the
severing tube of this invention;
[0032] FIG. 10 is a side and partial cross sectional view of the
extraction tube.
[0033] FIG. 11 is a front plan view of the front end of the head of
the extraction tube;
[0034] FIG. 12 is a partial cross sectional view of the electrode
array assembly and extraction sleeve positioned in an inner or
deployment cannula;
[0035] FIG. 13 is a side and partial cross sectional view of the
electrode array assembly deployed over the spinal dura when the
assembly foot is still disposed in the extraction sleeve;
[0036] FIG. 14 is a diagrammatic view of how the extraction sleeve
extends out of the body of the patient and the externally worn
power and control unit used to actuate the electrode array
assembly;
[0037] FIG. 14A is an enlarged view of where the extraction sleeve
is extends out of the portal formed in the patient;
[0038] FIG. 15 is a side and partial cross sectional view of how
the severing sleeve is employed to sever the extraction sleeve from
the deployed electrode array assembly;
[0039] FIG. 16 is a side and partial cross sectional view of how
the extraction tube is used to guide the removal the electrode
array assembly and the extraction sleeve; and
[0040] FIG. 17 is a top plan view of a second extraction tether of
this invention;
[0041] FIG. 18 is a side view of the electrode array assembly
deployed over tissue showing the extraction tether of FIG. 17
attached to the assembly;
[0042] FIG. 19 is a front plan view of a third extraction tether of
this invention;
[0043] FIG. 20 is a top view of the electrode array assembly
deployed over tissue showing the extraction tether of FIG. 19
attached to the assembly; and
[0044] FIGS. 21A and 21B are plan and cross sectional views of an
implantable pulse generator that can be used to transmit signals to
the electrode array assembly of this invention once the extraction
tether or sleeve is disconnected.
DETAILED DESCRIPTION
[0045] FIGS. 1, 2 and 3 and illustrate an electrode array assembly
40 constructed in accordance with this invention. Electrode array
assembly 40 is designed to be disposed against a section of tissue.
In the Figures, the assembly is disposed over the outer dura 42 of
the spinal cord 44. Assembly 40 includes a head 46, sometimes
called a paddle, that forms one end, the distal end of the
assembly. (In this document, "distal" is understood to be toward
the most forward edge of assembly head 46; "proximal" is understood
to be away from the most forward edge of the assembly head.) A
number of electrodes 48 are disposed on the surface of the head 46
and face the dura 42. Electrodes 48 are arranged in rows and
columns on head 46. In FIG. 1, a single row of electrodes 48 is
shown in phantom because the electrodes are on the surface of
assembly head 46 opposite the surface depicted in the Figure.
[0046] Assembly head 46 tapers inwardly to define a neck 50. Neck
50 thus has a width less than that of head 46. Continuing
proximally, the assembly neck 50 tapers outwardly to define a foot
52. In the illustrated version of the invention, assembly foot 52
has a width greater than that of head 42. In alternative versions
of the invention, foot 52 may have a width less than or equal to
that of the head 42. Foot 52 may even have a width equal to or less
than assembly neck 50.
[0047] An antenna 54 is disposed on assembly foot 52. Antenna 54
receives signals from an implantable generator disposed in the body
of the patient at some location spaced from assembly 40. Electrode
array assembly 40 includes a control circuit 58, represented by a
block on neck 50, that receives the signals developed across
antenna 54. Control circuit 58 stores the energy contained in these
signals. The control circuit 58 also demodulates the signals to
extract control signals. Based on the instructions contained within
the control signals, control circuit 58 causes current to flow
between specific combinations of the electrodes. This current flows
through the tissue between the electrodes so as to have a
therapeutic effect on the patient.
[0048] The Applicants' Assignee's PCT Pub No. WO 2008/080073 A2,
the contents of which are incorporated herein by reference,
describe how energy from a device worn by the patient is
transmitted to the implantable pulse generator (not illustrated)
and the implantable pulse generator transmits these signals to the
electrode array assembly. This document also describes how the
control circuit integral with the electrode array assembly: saves
the energy contained in the signals; extracts the commands based on
the signals and; based on the commands, causes current flow between
selected electrodes 48. Again, it should be understood that the
means by which signals are processed by electrode array assembly 40
are not relevant to this invention.
[0049] Also part of electrode array assembly 40 are one or more
extraction webs 62. Webs 62 hold the assembly to an extraction
sleeve 64 (FIG. 6). Once the assembly is so deployed 40, signals
are supplied to the antenna from an antenna (coil 106) within the
extraction sleeve 64. If, post deployment of the assembly 40, it
becomes necessary to extract the assembly, the assembly is removed
by pulling on the extraction sleeve 64. If such removal is not
required, sleeve 64 is severed from webs 62 and removed. This
leaves the electrode array assembly 40 in a fully deployed
state.
[0050] As seen by reference to FIGS. 4 and 5, the electrode array
assembly 40 of this invention includes a carrier 70. Carrier 70 is
formed from a superelastic material. This is a material that, after
being subjected to appreciable bending, rolling or other
deformation, returns to its initial state. One such superelastic
material is a nickel-titanium alloy such as the alloy marketed as
Nitinol.
[0051] In many embodiments of the invention, as part of the process
of fabricating the assembly, carrier 70 is given a shape to
facilitate conformance of the assembly to the tissue against which
the assembly is to be disposed. Thus, in a version of the assembly
intended for implanting against the spinal cord dura 42, carrier 70
is curved to have arc that is perpendicular to the longitudinal
axis of the assembly 40. Not all sections of the carrier may be so
curved. For example, in the above described version of the
invention only the head- and foot-defining portions of the carrier
may be so curved; neck 50 is not curved.
[0052] Bottom and top insulating layers 74 and 76, respectively,
are disposed over carrier 70. Insulating layers 74 and 76 are
formed from electrically insulating material. For example, in some
versions of the invention a polyxylene polymer film, such as
parylene-C which is available from Specialty Coating Systems, Inc.,
functions as the material from which the insulating layers are
formed. Electrodes 48 are over the bottom insulating layer 74, the
layer directed towards the dura 42. Antenna 54 and the assembly the
control circuit 58 are disposed on top insulating layer 76. (In the
Figures, the heights of the electrodes 48, antenna 54 and control
circuit 58 are exaggerated for purposes of illustration.)
[0053] Conductors 78 and 82 serve as the components over which
connections are established between the electrodes 48 and the
control circuit 58. Conductors 78 (only two shown in FIG. 1) are
connected to the control circuit 58 and are located on the top
insulating layer 76. Conductors 82 (only two shown in phantom in
FIG. 1) are disposed on the bottom insulating layer 74 and are
connected to the electrodes 48. Conductors 78 and 82 are connected
together by vias 80 (one shown in FIG. 4) that extend from bottom
insulating layer 74, through the carrier 70 to the top insulating
layer 76.
[0054] The Applicants' Assignee's U.S. patent application Ser. No.
12/475,920, METHOD OF ASSEMBLING AN ELECTRODE ARRAY THAT INCLUDES A
PLASTICALLY DEFORMABLE CARRIER, filed 1 Jun. 2009, now U.S. patent
Pub. Ser. No. ______, the contents of which is incorporated herein
by reference, discloses one means by which bottom insulating layer
74, electrodes 48 and conductors 82 are fabricated on a first side
of carrier 70. Once these components are so assembled on the
carrier, using the same method of the incorporated by reference
Pat. App. 61/057,684, the carrier 70 is inverted. Top insulating
layer 76, antenna 54 and conductors 78 are fabricated on the
surface of the carrier 70 opposite the surface on which the
electrodes 48 and conductors 82 are fabricated. During the process
steps in which antenna 54 and conductors 78 are formed on the
assembly, vias 80 are formed to extend through between the
conductors 78 and 82 and therefore through the carrier 70. Again,
it should be understood that, unless otherwise called out, the
process by which electrode array assembly 40 of this invention is
manufactured is not material to the invention.
[0055] FIG. 5 illustrates the structure of carrier 70 in more
detail. Prior to any bending operation, carrier 70 has a planar
shape. The carrier 70 is formed to define a head 86, a neck 88 and
a foot 90. Carrier head 86, neck 88 and foot 90 have outer
perimeters that generally correspond to the outer perimeters of
assembly head 46, neck 50 and foot 54, respectively. The width and
length of the assembly 40 is slightly greater then that of the
carrier 70. This difference is due to the fact that, while not
completely illustrated, in the completed assembly 40, a layer of
insulating material is disposed around the edge surfaces of the
carrier 70.
[0056] Carrier head 86 is formed with a number of tabs 87. Tabs 87
are located internal to the outer perimeter of the carrier 70. The
tabs 87 are defined by three sided slots 85. Tabs 87 are arranged
in rows and columns on the interior of the carrier head 86. As
described in the incorporated by reference U.S. Pat. App. No.
61/034,367, tabs 87 function as the sections of the carrier head 86
on which the electrodes 48 are formed.
[0057] In FIG. 1, electrodes 48 are seen disposed on tabs 49
integral with assembly head 46. Carrier tabs 87 and the insulating
material disposed over and under the carrier tabs 87 form the
assembly tabs 49. When the electrode assembly head 46 is rolled or
folded, tabs 49 and by extension, the electrodes 48 thereon, are
not rolled or folded to the extent the surrounding sections of the
electrode array assembly head is so rolled or folded. For reasons
of ease of illustration, the assembly tabs 49 are not seen in any
drawings other than FIG. 1.
[0058] Carrier 70 is further formed to have an opening 92 in the
neck 88 that is proximal to carrier head 86. Opening 92 is the
opening through which vias 80 extend through the carrier 70.
[0059] Carrier neck 88 is also formed to have additional openings
94 and 98 that while separate are spaced relatively close to each
other. Each of openings 92, 94 and 98 has a longitudinal axis that
extends perpendicular to the longitudinal axis of the carrier 70.
Openings 94 and 98 are closer to the carrier foot 90 than to
opening 92. Openings 94 and 98 define a bar 96 between the
openings. Bar 96, which is part of the carrier 70, has a
longitudinal axis that extends perpendicular to the longitudinal
axis of the carrier. A bridge 97, also part of the carrier bisects
opening 94 and 98 and carrier 96. Bridge 97 functions as the
portion of the carrier 70 over which conductors 78 extend over the
assembly neck 50 from the antenna 54 to control circuit 58.
[0060] Carrier foot 90 is formed to have an opening 102. Opening
102 defines the area on the top insulating layer 76 over which
antenna 54 is disposed. Opening 102 is present to prevent the
electromagnetic energy shielding tendencies of the metal-formed
carrier 70 from interfering with the receipt or transmission of
signals over antenna 54. In FIG. 5, opening 102 is shown has having
a generally rectangular shape and being wholly enclosed by the
carrier 70. It should be understood that the shape of the opening
and whether or not it is wholly surrounded or open may vary in
other versions of this invention.
[0061] In FIG. 4, the material forming top insulating layer 76 is
shown in openings 92 and 102. While not illustrated, it should
likewise be understood that at least the edges of the carrier that
define slots 85 and openings 94 and 98 are likewise covered with
insulating material.
[0062] The extraction sleeve 64, now described by reference to
FIGS. 6, 7 and 8, is formed from non-conductive, material that is
generally tubularly shaped. For example, the extraction sleeve 64
may be formed from a polymer tube that has an outer diameter of
between 1.5 and 5.0 mm and a wall thickness of between 0.05 and 0.5
mm. Extraction sleeve 64 has an open distal end, (end not
identified). Extraction webs 62 are formed integrally with the
extraction sleeve 64 and extend forward from the distal end face of
the sleeve.
[0063] Immediately proximal to the distal end of the sleeve 64 a
coil 106 is disposed in the extraction sleeve. In FIGS. 6 and 8,
coil 106 is depicted as a wire wrapped as a helix wherein the
individual turns are spaced apart from each other. At least one
conductor 108 extends proximally through the sleeve 64 from coil
86. In some versions of the invention, extraction sleeve 64 is
constructed by molding the sleeve around coil 106 and conductor
108. Alternatively, sleeve 64 is formed from inner and outer tubes
of material. Prior to the bonding of the two tubes of material to
form sleeve 64, coil 106 and conductor 108 are formed over the
inner sleeve or inside the inner wall of the outer sleeve. As a
consequence of the tube bonding process, coil 106 and conductor 108
are embedded on the extraction sleeve 64.
[0064] After electrode array assembly 40 of this invention is
assembled, the assembly foot 52 is rolled or folded and inserted in
the distal end of extraction sleeve 64. The forward ends, the
distal ends, of webs 62 are looped around carrier bar 96. In the
depicted version of the invention, two webs 62 are looped around
the carrier bar 96 from the top of assembly 40; two webs 62 are
looped around the carrier bar from the bottom of the assembly 40.
The free end of each web 62 is attached to a more proximal portion
of the web 62. An adhesive may be used to facilitate this
attachment. As a consequence of the seating of assembly 52 in the
distal end section of extraction sleeve 64, assembly antenna 54 is
disposed within the space enclosed by sleeve coil 106 as seen by
FIG. 8.
[0065] A severing tube 110, seen in FIG. 9, is used to disconnect
the electrode array assembly 40 from the extraction sleeve 64.
Severing tube 110 includes a tubular-shaped body 112 formed from
flexible material. One such material from which tube body can be
formed is Nitinol. Tube body 112 has an outer diameter that allows
the tube 110 to be slid in extraction sleeve 64.
[0066] Severing tube 110 has a ring-shaped head 114 attached to the
distal end of tube body 112 that forms the distal most end of the
tube 110. Head 114 is formed from metal such as medical grade
stainless steel. Head 114, like body 112, is dimensioned to slip
fit within extraction sleeve 64. In the illustrated version of the
invention, head 114 has an outer circumferential surface 116 with
the same outer diameter as body 112. Head 114 has the most distal
end of the head an inner circumferential surface 120. Surface 120
starts at the most forward end of outer surface 116 and tapers
inwardly from the distal end, the open end, of head 114. Thus,
severing tube head 114 is shaped to define between outer
circumferential surface 116 and inner circumferential surface 120 a
cutting edge 118. Cutting edge 118 is the most forward
circumferential face of head 114 and, by extension, severing tube
110.
[0067] In the illustrated version of the invention, inner
circumferential surface 120 does not extend the whole of the length
of head 114. Instead, surface 120 extends a distance equal to
approximately 20 to 75% of the length of head 114. Rearward of
surface 120, head 114 is shaped to have a second inner
circumferential surface, surface 122 that has constant diameter. In
some versions of the invention, surface 120 has a diameter equal to
the diameter of the adjacent bore-defining inner surface of tube
body 112.
[0068] In the event it is necessary to remove the electrode array
assembly 40 from the patient, an extraction tube 130, now described
by reference to FIGS. 10 and 11, is employed to so remove the
assembly. Extraction tube 130 has a tube body 134 formed from the
same material from which severing tube body 112 is formed. Tube
body 134 is formed to have an inner lumen 136 (shown in phantom)
with a diameter that allows the extraction sleeve 64, with assembly
foot 52 contained therein, to be drawn into the body 134.
[0069] Extraction tube 130 has a neck 138 and a head 140 formed as
a single unit, that is disposed over the distal end of tube body
134. Neck 138 and head 140 may be formed from metal or from a
plastic that is more rigid from which tube body 134 is formed. Neck
138 is generally ring shaped and has inner and outer diameters that
are generally identical to the inner and outer diameter of
extraction tube body 134.
[0070] Head 140 generally is generally horn shaped. That is, both
the inner and outer walls of the head 140 flare outwardly from the
distal end of the neck 138. In the illustrated version of the
invention, head 140 has in a plane perpendicular to the
longitudinal axis of the neck 138 and head 140 an elliptical cross
sectional profile. That is, head flares outwardly more along a
first axis perpendicular to the longitudinal axis than along a
second axis this is perpendicular to both the longitudinal and the
first axis. Head 140 is further formed so as to have rounded edge
142 between the inner and outer circumferential surfaces. Rounded
edge 142 thus functions as the most forward face of head 140 and,
therefore, of extraction tube 130.
[0071] As mentioned above, once electrode array assembly 40 is
fabricated, foot 52 is rolled or fabricated so the foot can be
inserted in the open distal end of the extraction sleeve 64. In
FIG. 8, foot 52 is shown as being in a rolled state. Webs 62 are
looped around carrier bar 62 and their ends attached to their more
proximal portions.
[0072] The electrode array assembly-and-extraction sleeve assembly
is then placed in an inner cannula, sometimes referred to as a
deployment cannula 150, seen in FIG. 12. Deployment cannula 150 is
placed in an outer cannula sometimes referred to as an access
cannula (access cannula not illustrated). Also, prior to insertion
of the deployment cannula 150 with the assembly contained therein,
a flexible stylet (not illustrated) may be fed through the cannulae
and the extraction sleeve. The distal end of the stylet abuts the
proximal end of the electrode array assembly foot 52.
[0073] Electrode array assembly 40 is deployed by first positioning
the access cannula in close proximity to the tissue over the tissue
over with which electrode array assembly is to be disposed. The
deployment cannula 150, with the electrode array
assembly-and-extraction sleeve assembly contained therein, is
pushed forward over the target tissue. During advancement of the
deployment cannula 150, the deployment cannula 150 may be rotated
relative to the access cannula.
[0074] Once the deployment cannula 150 is in position, the
deployment cannula 150 is retracted back into the access cannula.
At the time of the retraction of the deployment cannula, the stylet
holds the electrode array assembly-and-extraction sleeve assembly
so that this assembly does not retract back into the access cannula
with the deployment cannula 10. A more detailed understanding of
this process may be found in the incorporated by reference PCT Pat.
App. No. PCT/US2009/033769.
[0075] As a consequence of the retraction of deployment cannula 150
and the superelasticity of the assembly carrier 70, as depicted in
FIG. 13, the assembly head 46 deploys over the surface of the
tissue over which the head is to be positioned. Assembly foot 52
remains contained in extraction sleeve 64. Extraction sleeve 64
thus rests on the surface of the tissue adjacent the tissue over
which the assembly head 46 is deployed. In FIG. 13, the height of
the extraction sleeve above the tissue and assembly head 46 is
exaggerated for purposes of illustration.
[0076] Owing to its length, after withdrawal of the access and
deployment cannulae, the proximal end of the extraction sleeve 64
extends out of the body as seen in FIGS. 14 and 14A. More
particularly, the extraction sleeve extends out of the portal
formed in the body through which the cannulae where introduced into
the body. Conductor 108 is connected to a power and control unit
156 adapted to be worn externally by the individual in whom the
electrode array assembly 40 is implanted.
[0077] Power and control unit 156 is programmed to determine if
assembly 40 can provide the desired therapeutic effect.
Specifically, power and control unit 156 is programmed to output
signals containing instructions indicating between which sets of
electrodes currents are to be flowed. These signals are generated
by unit 156 and output over conductor 108 to coil 106. Coil 106
functions as antenna that broadcasts the signals to the adjacent
electrode array assembly antenna 54. Control circuit 58 both
extracts the power from the signals received by antenna 54 and
decodes the instructions contained in the signals. Based on the
decoded instructions, control circuit 58 causes current to flow
between the specified sets of electrodes 48.
[0078] The current flow between the electrodes 48 flows through the
tissue underlying the electrodes. The patient is monitored to
determine if this current flow has the desired therapeutic effect
and results in tolerable side effects. During this evaluation
process, unit 156 typically is reprogrammed to output instructions
that cause the currents to be flowed through different sets of
electrodes. This resetting of the current flow patterns through the
patient's tissue is performed to determine which current flow
results in an optimal combination of desirable benefits and
acceptable side effects.
[0079] Ideally, during this evaluation process, it becomes apparent
that the electrode array assembly 40 provides the desired benefits
with, at the most, acceptable side effects. In this situation, the
extraction sleeve 64 is removed. The removal is performed by
sliding severing tube 110 down the center lumen of the extraction
sleeve 64 as seen in FIG. 15. When the tube head 114 approaches the
assembly 40, the assembly foot 52 slides up against the inner
circumferential surface 120 of the head 114. The assembly foot 52
thus becomes encased in the tube body 112 and head 114. Severing
tube 110 is continued to be pressed forward so that head cutting
edge 118 presses against and cuts webs 62.
[0080] During the process of pressing severing tube 110 against
webs 62, it may be necessary to apply a restraining force to the
extraction sleeve 64. This force prevents sleeve 64 and attached
electrode array assembly 40 from moving forward when the severing
tube head 114 is pressed against webs 62. A flexible stylet
threaded down the extraction sleeve 64 so as to abut the electrode
array assembly 40 can provide this force.
[0081] Once the webs 62 are cut, extraction sleeve 64, and severing
tube 110 encased therein, are withdrawn from the patient. Owing to
the superelastic nature of assembly carrier 70, assembly foot 52
unrolls or unfolds to extend over the tissue adjacent the tissue
over which the assembly head 46 is deployed as seen in FIG. 3.
Electrode array assembly 40 can now be considered permanently
implanted in the patient. Once this procedure is performed, a pulse
generator 158, seen in FIGS. 21A and 21B, is implanted in the
patient. As described in the incorporated herein by reference PCT
Pub. No. WO 2008/080073, this pulse generator 158 includes a
housing 159 in which two antennae 160 and 166 are embedded. Antenna
160 is used to receive signals from a source external to the
patient. A circuit internal to housing 159, represented by
components 162, converts these signals into a form in which they
can be used by the electrode array assembly 40. The converted
signals are applied to antenna 166. Antenna 166 wirelessly
transmits signals to array antenna 52. As before, control circuit
58 harvests the power from these signals and decodes the signals.
Based on the decoded instructions, control circuit 58 causes the
inter-electrode current flow necessary to have the desired
therapeutic effect. The exact structure of this implantable pulse
generator is not part of the current invention.
[0082] There are situations though during the evaluation process in
which it is determined that the current flows through the patient's
tissue does not have the desired benefit or the side effects of
such current flow are not tolerable. This determination may be made
even though by reprogramming power and control unit 156, currents
were flowed through different sets of electrodes 48 and, therefore
by extension, through different sections of tissue underlying the
assembly 40.
[0083] In this event, there is no reason to leave the electrode
array assembly 40 in the patient. Accordingly, the extraction tube
130 is inserted in the portal around the extraction sleeve 64 and
feed forward to the electrode array assembly. As a consequence of
the of the extraction tube 130 sliding over the distal end of the
extraction sleeve 64, the assembly foot 52 lodges in the distal end
of the tube body 134 and tube head 140 as seen in FIG. 16. Owing to
the relative dimensioning of the extraction sleeve 64 as well as
the extension tied to it and the extraction tube, at this time the
extraction sleeve extends out of the proximal end of extraction
tube body 132. The proximal end of the extraction sleeve 64 is
pulled on to draw the electrode array assembly neck 50 and then
head 46 into the tube body 134. As the electrode array assembly
head moves into tube 130, the outer portions of the assembly head
46 move against the wide to narrow tapered surface of tube head
140. This movement of the assembly head 46 against tube head 134
folds the outer portions of the assembly head inwardly. Once
folded, these portions of the assembly head 46 are able to slide
within the lumen 136 of the tube body 134.
[0084] Once the electrode array assembly 40 is disposed within the
extraction tube, the tube 130, with assembly 40 and sleeve 64
contained therein, is withdrawn from the patient. The withdrawal of
the extraction tube 130 thus removes the electrode array assembly
40 from the patient.
[0085] Electrode array assembly 40 and the complementary components
of this invention are designed so that the assembly 40 serves as
its own evaluation assembly. During the evaluation period, the
energy and power containing signals are transmitted wirelessly to
the assembly 40 from the external power and control unit 156
through extraction sleeve 64. This eliminates the need to initially
implant a pulse generator in a patient before it has been
determined that the assembly 40 provides a beneficial effect.
[0086] Ideally, once implanted, it is determined in the evaluation
procedure that the assembly provides the desired therapeutic
effects. In this situation, the patient is subjected to a minor
procedure to disconnect the extraction sleeve 64 from the assembly
40 and withdraw the sleeve. The need to subject the patient to a
second more complicated medical procedure to withdraw a test
electrode array and then install the permanent array is
eliminated.
[0087] Further, since electrode array assembly 40 serves as its own
test array, the possibility that the replacement of a test array
with a permanent electrode array results in the mispositioning of
the permanent array is likewise eliminated.
[0088] However, there will be instances in which during the
evaluation period it is determined that the electrode array
assembly 40 is not able to provide the patient with the desired
therapeutic effects or the side effects are not tolerable. When
this situation occurs, the extraction sleeve 64 and extraction tube
130 are collectively employed to withdraw, extract, the assembly 40
from the patient. The assembly is withdrawn through the previously
formed portal in the patient. Again, this minimizes the trauma to
which the patient is subjected.
[0089] It should be appreciated that the foregoing is directed to
one specific version of the invention. Certain features of the
invention may differ from what has been described.
[0090] For example, means other than the described web-around-bar
arrangement may be used to hold the electrode array assembly 40
within extraction sleeve 64. In some versions of the invention,
webs 62 maybe adhesively or heat bond secured to one or more of the
exposed surfaces of the electrode array assembly.
[0091] Alternatively, a structural device other than a sleeve may
serve as the extraction device connected to the electrode array
assembly to which the withdrawal force is applied. FIGS. 17 and 18
illustrate how a planar strip of plastic functions as the
extraction tether 170. In this version of the invention, extraction
tether 170 has a relatively narrow body 172. A head 174 with a
width greater than body 172 is located at the distal end of the
body 172. A nose 176 with a width less than that of head 174
extends forward from the head. Nose 176 thus forms the most distal
end of extraction tether 170.
[0092] In this version of the invention, tether 170 is positioned
so that head 174 is disposed over assembly foot 52. Nose 176 is
secured to the assembly 40 forward of antenna 54. In some versions
of the invention, the most distal end of tether nose 176 is looped
around carrier bar 96 and secured to a more proximal section of the
nose 176. Alternatively, the nose 176 is adhesively secured to the
electrode array assembly 40.
[0093] Tether body 172 has two arms 178. Each arm 178 is in the
form of a section of the body 172 that is separated from the
adjacent section of the body a small slot formed in the body (slot
not identified). The arms 178 are located along the opposed outer
longitudinally extending sides of the body 172. Arms 178 are
located immediately proximal to tether head 174. Each arm 178 is a
three-sided structure. The arms 178 thus extend from fold line 179.
Each arm 178 bends down from the adjacent section of the tether
body 172.
[0094] The forward end, the distal end, of each tether arm 178 is
attached to the proximal end of the associated electrode array
assembly foot 52. Just as an adhesive is used to secure tether nose
176 to the electrode array assembly 40, an adhesive may be used to
secure the arms to the assembly.
[0095] An antenna 180 is disposed in tether head 174. In the
illustrated version of the invention, the antenna 184 is in the
form of a spiral wrapped wire. At least one conductor 182 extends
proximally from antenna 180 through tether body 172.
[0096] When tether 170 is attached to electrode array assembly,
tether head 174 is disposed over assembly foot 52. Tether nose 176
and arms 178 connect tether 170 to assembly 40 at opposed ends of
the assembly foot 52. Tether antenna 180 overlaps assembly antenna
54.
[0097] The above described version of the invention works in the
same general manner in which the first described version functions.
The electrode array assembly-and-tether assembly is implanted at
the location where it is believed current flow through the tissue
will have the desired therapeutic effect. Signals are transferred
between the tether antenna 180 and the underlying assembly antenna
54.
[0098] If, during the evaluation period, it is determined that the
assembly 40 provides the desired therapeutic effect, tether 170 is
removed. A severing tube similar to the previously described
severing tube 110 may be used to perform this function. The
severing tool of this version of the invention may have small inner
and outer diameters than tool 110. This is because the width of the
tether body 172 is less than the width of the assembly foot 52 even
when the foot is folded or rolled. As the severing tool approaches
the distal end of the tether 170 the tether head 174 folds into the
severing tool. By pushing forward on the severing tube, the tube
head first cuts tether arms 178 and then tether nose 176 so as to
separate extraction tether 170 from electrode array assembly
40.
[0099] If it is necessary to remove the electrode array assembly,
an extraction tube similar to the previously described extraction
tube 130 is employed. Since the extraction tether 170 has an on
overall circumference that is less than the previously described
extraction sleeve, the extraction tube of this invention may be of
smaller diameter than the previously described extraction tube 130.
The extraction tube is fed over the extraction tether body 172
until the head of the tube is close to tether head 174. At this
time force is applied to the proximal end of the extraction tether
body 172 to pull the tether 170 into the extraction tube. Since,
the tether nose 176 and arms 178 are connected to the electrode
array assembly 40, the retraction of the tether 170 into the
extraction tube results in a like retraction of the electrode array
assembly 40. As part of this process, first the extraction tether
arms 178 and then the head 176 pull the electrode array assembly 40
into the head of the extraction tube. Once the electrode array
assembly 40 is disposed in the extraction tube, the tube is
withdrawn from the patient to complete the extraction process.
[0100] FIGS. 19 and 20 illustrate an alternative extraction tether
190 of this invention. Tether 190 is in the form of a flexible tube
formed of polymer that has an oval cross sectional profile. Two
parallel lumens 192 and 194 extend longitudinally through tether
190, (lumens seen in phantom in FIG. 20. A wire 196 extends from
the proximal end of bore 192 out through the distal end of tether
190. Wire 196 is coated with a biocompatible insulating
material.
[0101] As part of the process of preparing the electrode array
assembly 40 for deployment, wire 196 is passed through an opening
202 in the proximal end of the assembly foot 52. More particularly,
the opening 202 is formed in a section of the assembly wherein
carrier 70 is present so that the wire passes through an opening in
the carrier. Wire 196 is inserted back into the tether and more
particularly lumen 192. The wire is feed through lumen 192 so as to
extend out of the proximal end of the tether 190. The looping of
the wire 196 through opening 202 and the feeing of the wire back in
tether lumen 194 releasably attaches tether 190 to the electrode
array assembly 40.
[0102] Electrode array assembly 40 with attached tether 190 is then
disposed in the deployment cannula 150. The electrode array
assembly 40 is then deployed over the target tissue as described
before. Upon deployment from cannula 150, the assembly foot 52 is
not constrained. Therefore, the assembly foot 52, like the assembly
head is free to unfold or unroll over the target tissue.
[0103] As part of the process of deploying assembly 40, the
proximal end of tether 190 is left to extend out of the portal in
the body of the patient. At least one end of wire 196 is tied to a
terminal integral with power and control unit 156. The opposed end
of wire 196 is also tied to a static anchor. This anchor may be
attached to the power and control unit 156. The anchor may be a
second electrical terminal of the pulse generator.
[0104] During the evaluation process, the signals output by the
power and control unit 156 are output over wire 196. Wire 196
functions as the antenna over which the signals are broadcast to
assembly antenna 54.
[0105] As a result of the evaluation process, it may be determined
that assembly 40 provides the desired therapeutic effect. Tether
190 is initially disconnected from the assembly 40 by first
disconnecting wire 196 from at least one of the anchors (terminals)
to which the wire is connected. One end of the wire 196 extending
out of the proximal end of the tether 190 is pulled so as to cause
the free end of the wire to first be withdrawn through the tether
lumen 192 or 194 in which the wire is seated. The wire is then
withdrawn from the assembly through assembly opening 202 and out of
the second lumen 194 or 192. The withdrawal of wire 196 from
assembly bore 202 is the disconnecting of tether 190 from the
electrode array assembly 40.
[0106] In this described version of the invention, the free end of
the wire 196, when it initially travels proximally through tether
190 travels in its own lumen 192 or 194. This eliminates the
possibility that the free end of the wire 196 could somehow bind
against the adjacent section of wire. If such binding were allowed
to occur, it could result in the loop of wire 196 forward of the
distal end of the tether 190 simply tightening and pulling the
electrode array assembly 40 towards the tether.
[0107] Once tether 190 is disconnected from the electrode array
assembly 40, a force is applied to the tether to withdraw the
tether from the patient.
[0108] If, after the evaluation period it is determined that it is
necessary to remove the electrode array assembly 40, an extraction
tube 130 may be passed over tether 190 and directed towards the
assembly. Once the extraction tube is adjacent the electrode array
assembly 40 a force is applied to the proximal end of the tether
190. this force causes the tether to pull the electrode array
assembly 40 into the extraction tube.
[0109] An advantage of this version of the invention is that, the
need insert a tool into the body, disconnect the tether 190 from
the electrode array assembly 40 is eliminated.
[0110] It should be appreciated that, in alternative versions of
the above-described embodiment of the invention, a separate
conductor, as opposed to wire 196, may function as the tether
antenna. In these versions of the invention, the distal end of the
tether may have an enlarged head on which the antenna is
disposed.
[0111] Similarly, in alternative versions of the invention the webs
or other members that hold the extraction tether to the electrode
array assembly may be integrally part of the electrode array
assembly. In these versions of the invention the free ends of the
webs, which are spaced from the electrode array assembly 40 are
adhesively or mechanically secured to the extraction tether or
sleeve.
[0112] The shapes of the components may of course differ from what
has been described. Thus, there is no obligation that components
like the extraction tether or the extraction sleeve always have
circular cross sectional profiles. In some versions of the
invention it may be desirable to provide an extraction sleeve 64
that has an oval or oblong cross sectional profile. An oval or
oblong extraction sleeve 64, could for example have major and minor
outer diameters of, respectively, approximately 3.5 and 2.0 mm.
[0113] In some versions of the invention, simply pulling on the
extraction tether or sleeve may be all that is required to withdraw
the electrode array assembly from the tissue against which the
assembly is deployed. These versions of the invention eliminate the
need to provide an extraction tube.
[0114] In versions of the invention wherein the tether is the loop
of wire, the associated sleeve may have a single lumen.
Alternatively, in some versions of this construction of the
invention, there may not even be a need to encase the wire in a
sleeve.
[0115] Similar in versions of the invention whether the tether
includes the loop of wire, the wire may not function as the
temporary antenna. In these versions of the invention, wire
embedded or routed in the tube, tube 190, performs the antenna
function. In some embodiments of these versions of the invention,
the wire, in addition to functioning as the mechanical connect to
the electrode array assembly functions as the conductor over which
signals are supplied from the external unit to the antenna embedded
in the tube. Alternatively, conductors separate fro the wire
embedded or routed in the tube serve as the elements over which the
signals are supplied to the tube antenna.
[0116] Therefore, it is the object of the appended claims to cover
all such variations and modifications that come within the true
spirit and scope of this invention.
* * * * *