U.S. patent application number 11/673001 was filed with the patent office on 2007-08-16 for self-folding paddle lead and method of fabricating a paddle lead.
Invention is credited to John W. Swanson.
Application Number | 20070191709 11/673001 |
Document ID | / |
Family ID | 37985318 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070191709 |
Kind Code |
A1 |
Swanson; John W. |
August 16, 2007 |
SELF-FOLDING PADDLE LEAD AND METHOD OF FABRICATING A PADDLE
LEAD
Abstract
In one embodiment, a medical lead comprises a lead body for
conducting electrical pulses and a paddle. The paddle includes an
intermediate metal layer, at least an insulative polymer backing
layer, and an insulative polymer covering layer. The intermediate
metal layer comprises a plurality of features defined by gaps in
the metal material in the metal layer such that each feature is
electrically isolated from each other feature, wherein each feature
includes a respective connector element that is electrically
coupled to at least one conductor within the lead body, wherein a
portion of the insulative polymer covering layer is exposed above
each feature to define a respective electrode for the corresponding
feature. Also, the paddle possesses shape memory to cause the
paddle to assume a substantially planar orientation when the shape
memory is in a relaxed state.
Inventors: |
Swanson; John W.; (Portland,
OR) |
Correspondence
Address: |
ADVANCED NEUROMODULATION SYSTEMS, INC.
6901 PRESTON ROAD
PLANO
TX
75024
US
|
Family ID: |
37985318 |
Appl. No.: |
11/673001 |
Filed: |
February 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60772321 |
Feb 10, 2006 |
|
|
|
Current U.S.
Class: |
600/433 |
Current CPC
Class: |
Y10T 29/49204 20150115;
A61N 1/0553 20130101; A61N 1/36071 20130101; A61B 5/296 20210101;
A61B 5/283 20210101 |
Class at
Publication: |
600/433 |
International
Class: |
A61B 6/00 20060101
A61B006/00 |
Claims
1. A medical lead for delivering electrical stimulation to tissue
of a patient, the medical lead comprising: a lead body for
conducting electrical pulses through a plurality of conductors; and
a paddle for delivering the electrical pulses from the plurality of
conductors to tissue of the patient, wherein the paddle includes:
(i) an intermediate metal layer; and (ii) at least an insulative
polymer backing layer and an insulative polymer covering layer;
wherein the intermediate metal layer comprises a plurality of
features defined by gaps in the metal material in the metal layer
such that each feature is electrically isolated from each other
feature, wherein each feature includes a respective connector
element that is electrically coupled to at least one conductor
within the lead body, wherein a portion of the insulative polymer
covering layer is exposed above each feature to define a respective
electrode for the corresponding feature; wherein the paddle
possesses shape memory to cause the paddle to assume a
substantially planar orientation when the shape memory is in a
relaxed state.
2. The medical lead of claim 1 wherein the guide structures are
scribed into at least one of a plurality of separate features of
the paddle, the guide structures being adapted to control folding
or unfolding of the paddle.
3. The medical lead of claim 1 wherein intermediate metal layer
possesses a thickness of approximately one mil.
4. The medical lead of claim 1 wherein the insulative polymer
backing layer possesses a thickness of approximately 25.4 to 152.4
microns.
5. The medical lead of claim 1 wherein the paddle comprises a slit
in the paddle and the first longitudinal portion folds over the
second longitudinal portion upon application of force to the
paddle.
6. The medical lead of claim 1 further comprising: a support
structure that extends substantially along a longitudinal direction
of the paddle, the paddle being affixed to a flat surface of the
support structure and the medical lead being affixed to a concave
surface of the support structure.
7. The medical lead of claim 6 wherein the support structure is an
extruded or injection-molded biocompatible polymer structure.
8. A method of fabricating a paddle adapted for electrical
stimulation of tissue of a patient, the method comprising:
providing a layer of conductive material; laminating a film of
insulative material on a first side of the layer of conductive
material; creating a paddle form in the layer of conductive
material, the paddle form including: (i) at least a first segment
and a second segment with a plurality of electrodes on each
segment; and (ii) one or more guide structures proximate to at
least one end of the paddle form, wherein the one or more guide
structures are adapted to distribute force into a body of the
paddle form to control folding or unfolding of the paddle form; and
providing an insulative layer over the paddle on a second side of
the layer of conductive material; wherein the paddle possesses
shape memory that causes the paddle to assume a substantially
planar state when the shape memory is in a relaxed state.
9. The method of claim 8 wherein the providing an insulative layer
comprises: spin coating an insulative polymer on the paddle.
10. The method of claim 8 wherein the creating comprises: laser
scribing the conductive material without completely cutting through
the film of insulative material.
11. The method of claim 8 further comprising: removing portions of
insulative material to expose conductive material corresponding to
the plurality of electrodes.
12. The method of claim 8 wherein the guide structures are
longitudinal elements that distribute force into the body of the
paddle to cause the paddle to fold.
13. The method of claim 8 further comprising: mechanically coupling
the paddle to a support structure; and electrically coupling the
electrodes of the paddle to conductors of a medical lead.
14. The method of claim 13 wherein the medical lead is mechanically
coupled to a concave surface of the support structure and the
paddle is mechanically coupled to a flat surface of the support
structure.
15. The method of claim 8 wherein, after the creating the paddle
form is performed, the conductive material occupies substantially
all of the surface area of the paddle.
16. The method of claim 8 wherein the paddle form comprises a slit
in the conductive material and the first segment folds over the
second segment when either of the guide structures experiences
force by contact of the paddle with an interior surface of an
insertion tool.
17. The method of claim 16 wherein the slit in the conductive
material is covered by a highly elastic polymer material or
hydrogel material.
18. A method of positioning a paddle-style lead in a patient for
electrical stimulation of tissue of the patient, comprising:
inserting a paddle structure of the lead into an insertion tool or
catheter, the paddle structure including at least a first
longitudinal portion and a second longitudinal portion, the first
and second longitudinal portions defining respective substantially
planar surfaces having a plurality of electrodes, wherein contact
of the paddle structure with an interior portion of the insertion
tool or catheter causes one or several memory shape elements in the
paddle structure to be subjected to a compressive force; and
advancing the paddle structure in a folded state through the
insertion tool or catheter to exit the insertion tool or catheter
within the patient, wherein the planar surfaces of the first and
second longitudinal portions are disposed substantially adjacent to
each other in the folded state; wherein release of the compressive
force on the one or several shape memory elements upon the exiting
of the paddle from the insertion tool or catheter causes unfolding
of the paddle structure to occur in a substantially lateral
direction.
19. The method of claim 18 wherein the paddle structure comprises
one or more guide structures that possess an arcuate shape to
distribute force into the second longitudinal portion and one or
more guide structures that possess a substantially linear shape to
distribute force into the first longitudinal portion.
20. The method of claim 19 wherein the one or more guide structures
of the first and second longitudinal portions cause the paddle to
possess a differential in rigidity between the first and second
longitudinal portions.
Description
RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Patent Application Ser. No. 60/772,321, filed Feb. 10,
2006, entitled "SELF-FOLDING PADDLE LEAD AND METHOD OF FABRICATING
A PADDLE LEAD," which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present application is generally related to a paddle
lead that is self-folding for insertion in a patient using an
insertion tool or catheter and that returns to an extended state
upon exiting the insertion tool or catheter within the epidural
space.
BACKGROUND
[0003] Application of electrical fields to spinal nerve roots,
spinal cord, and other nerve bundles for the purpose of chronic
pain control has been actively practiced for some time. While a
precise understanding of the interaction between the applied
electrical energy and the nervous tissue is not fully appreciated,
it is known that application of an electrical field to spinal
nervous tissue (i.e., spinal nerve roots and spinal cord bundles)
can effectively mask certain types of pain transmitted from regions
of the body associated with the stimulated nerve tissue.
Specifically, applying electrical energy to the spinal cord
associated with regions of the body afflicted with chronic pain can
induce "paresthesia" (a subjective sensation of numbness or
tingling) in the afflicted bodily regions. Thereby, paresthesia can
effectively mask the transmission of non-acute pain sensations to
the brain.
[0004] It is known that each exterior region, or each dermatome, of
the human body is associated with a particular longitudinal spinal
position. Thus, electrical stimulation of nerve tissue must occur
at a specific longitudinal location to effectively treat chronic
pain. Additionally, it is important to avoid applying electrical
stimulation of nerve tissue associated with regions of the body
that are unaffected by chronic pain. Positioning of an applied
electrical field relative to a physiological midline is also
important.
[0005] Percutaneous leads and laminotomy leads are the two most
common types of lead designs that provide conductors that deliver
stimulation pulses from an implantable pulse generator (IPG) to
distal electrodes adjacent to the nerve tissue. As shown in FIG.
1A, conventional percutaneous lead 100 includes electrodes 101 that
substantially conform to the body of the body portion of the lead.
Due to the relatively small profile of percutaneous leads,
percutaneous leads are typically positioned above the dura layer
through the use of a Touhy-like needle. Specifically, the
Touhy-like needle is passed through the skin, between desired
vertebrae to open above the dura layer for the insertion of the
percutaneous lead.
[0006] As shown in FIG. 1B, conventional laminotomy or paddle lead
150 has a paddle configuration and typically possesses a plurality
of electrodes 151 (commonly, two, four, eight, or sixteen) arranged
in one or more columns. Multi-column laminotomy leads enable
reliable positioning of a plurality of electrodes. Also, laminotomy
leads offer a more stable platform that tends to migrate less after
implantation and that is capable of being sutured in place.
Laminotomy leads also create a uni-directional electrical field
and, hence, can be used in a more electrically efficient manner
than conventional percutaneous leads. Due to their dimensions and
physical characteristics, conventional laminotomy leads require a
surgical procedure for implantation. The surgical procedure (a
partial laminectomy) is evasive and requires the resection and
removal of certain vertebral tissue to allow both access to the
dura and proper positioning of a laminotomy lead.
SUMMARY
[0007] In one embodiment, a medical lead comprises a lead body for
conducting electrical pulses and a paddle. The paddle includes an
intermediate metal layer, at least an insulative polymer backing
layer, and an insulative polymer covering layer. The intermediate
metal layer comprises a plurality of features defined by gaps in
the metal material in the metal layer such that each feature is
electrically isolated from each other feature, wherein each feature
includes a respective connector element that is electrically
coupled to at least one conductor within the lead body, wherein a
portion of the insulative polymer covering layer is exposed above
each feature to define a respective electrode for the corresponding
feature. Also, the paddle possesses shape memory to cause the
paddle to assume a substantially planar orientation when the shape
memory is in a relaxed state.
[0008] The foregoing has outlined rather broadly certain features
and/or technical advantages in order that the detailed description
that follows may be better understood. Additional features and/or
advantages will be described hereinafter. It should be appreciated
by those skilled in the art that the conception and specific
embodiment disclosed may be readily utilized as a basis for
modifying or designing other structures for carrying out the same
purposes. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the appended claims. The novel features, both as to
organization and method of operation, together with further objects
and advantages will be better understood from the following
description when considered in connection with the accompanying
figures. It is to be expressly understood, however, that each of
the figures is provided for the purpose of illustration and
description only and is not intended as a definition of the limits
of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1A and 1B depict a conventional percutaneous lead and
a conventional paddle lead, respectively.
[0010] FIG. 2 depicts a self-folding flexible paddle according to
one representative embodiment.
[0011] FIG. 3 depicts a flowchart for fabricating the paddle shown
in FIG. 2 according to one representative embodiment.
[0012] FIG. 4A depicts a cross-sectional view of a paddle lead
including the paddle shown in FIG. 2 according to one
representative embodiment. FIGS. 4B-4D depict the "sliding" folding
progression of the paddle of the paddle lead shown in FIG. 4A
according to one representative embodiment.
[0013] FIGS. 5A-5H depict placement of a paddle lead within the
epidural space of a patient according to one representative
embodiment.
[0014] FIG. 6 depicts a foldable paddle lead coupled to an
implantable pulse generator according to one representative
embodiment.
[0015] FIG. 7 depicts a foldable paddle lead that folds in a manner
similar to a page being turned in a book.
DETAILED DESCRIPTION
[0016] FIG. 2 depicts a schematic representation of flexible paddle
200 according to one representative embodiment. Flexible paddle 200
is preferably fabricated using laminated layers of biocompatible
polymer(s) and one or several thin layers of suitable conductive
material. The conductive material may cover almost all of the
surface area of the polymer backing. Specifically, the various
structures (electrodes, guides, connector elements) are preferably
defined by scribing or etching borders or edges between these
structures. In such embodiments, the conductive material provides
sufficient shape memory to cause the paddle structure to assume a
planar shape in a relaxed state. In alternative embodiments, one or
more layers of the polymer may be utilized to provide the desired
mechanical characteristic.
[0017] The width of paddle 200 is sufficient to provide suitable
spacing between the two sets of electrodes 203 to enable
stimulation of the pertinent nerve fibers across the physiological
midline of the patient. The design of paddle 200 enables paddle 200
to be substantially maintained at a desired position within the
patient's epidural space. Moreover, the design of paddle 200
ensures that electrodes 203-1 through 203-8 will remain in fixed
relative positions, e.g., electrodes 203-1 through 203-4 cannot be
offset longitudinally from electrodes 203-5 through 203-8.
[0018] Paddle 200 includes guide structures 202-1 and 202-2 which
are proximate to distal end 201 of the paddle. Guide structures
202-1 and 202-2 cause paddle 200 to fold upon itself when the guide
structures 200 contact the lumen of an insertion tool. In some
embodiments, the guide structures 202-1 and 202-2 are implemented
by scribing longitudinal elements in the conductive material. When
paddle 200 contacts the inner surface of the insertion tool, the
longitudinal elements distribute force into the body of paddle 200
according to the shape of the respective longitudinal elements.
Additionally, guide structures 202-1 and 202-2 are preferably
implemented to possess different amounts of rigidity (e.g., due to
the shape of the respective guide structures 202, the thickness of
their respective longitudinal members, etc.). The difference in the
amount of rigidity controls the manner in which paddle 200 folds.
As will be discussed in greater detail below, one side of paddle
200 folds over the other side in a substantially lateral manner
thereby minimizing the amount of open space within the epidural
space required for paddle 200 to unfold.
[0019] In the embodiment shown in FIG. 2, paddle 200 includes slit
204 in the middle of the lead paddle to provide a portion of the
paddle with a very small modulus. Slit 204 may be defined by
removing at least the conductive material. If the outer insulative
material provides an undue amount of rigidity at this point, the
insulative material may also be removed or replaced with a lower
modulus material with improved elasticity. When distal end 201 is
initially inserted within a suitable insertion tool, guide
structures 202-1 and 202-2 experience force associated with the
contact with the inner wall of the insertion tool. The force
associated the contact and the presence of slit 204 cause segment
210 of paddle 200 to fold over segment 220. In one embodiment,
after paddle 200 has been folded, the entire width of paddle 200 is
fit within the insertion tool. Thus, the paddle can be advanced
through the tool into the patient's epidural space. Also, once the
paddle is pushed through the insertion tool, the shape memory
characteristics of the laminate structure cause paddle 200 to
unfold thereby exposing electrodes 203-1 through 203-8 to the
spinal tissue. Preferably, the shape memory provides sufficient
force to displace fibrous tissue or scar tissue within the epidural
space. However, the expansive force of the shape memory is also
preferably limited to avoid damage to other tissue. In some
embodiments, one or more laminate film layers and/or the conductive
material cause paddle 200 to possess memory or a spring
characteristic.
[0020] In a similar manner, if paddle 200 needs to be removed from
the patient, distal end 205 and guide structures 202-2 and 202-3
are provided. Specifically, proximal end 205 can be pulled by lead
body 410 into the same or similar tool as used to insert paddle
lead 200. When guide structures 202-2 and 202-3 experience force
due to contact of paddle 200 with the inner wall of the tool,
segment 210 once again folds over segment 220 thereby enabling
paddle 200 to be withdrawn from the patient's epidural space
through the tool. Accordingly, it is not necessary to perform a
partial laminectomy procedure for the insertion or removal of
paddle 200.
[0021] Numerous variations upon the design shown in FIG. 2 are
possible. For example, paddle 200 need not include slit 204. The
center portion of paddle 200 could be rigid and both of segments
210 and 220 could fold when paddle 200 is inserted into an
insertion tool. Alternatively, slit 204 could be moved from the
middle of the paddle. Also, multiple slits 204 could be used to
create multiple folding segments. Also, slit 204 need not
necessarily remain as a void between the front and back sides of
paddle 200. Instead, the conductive material and/or the original
insulative material may be removed and a relatively thin portion of
highly elastic polymer or hydrogel material, as examples, may be
provided at slit 204 to prevent tissue growth from occurring
through paddle 200.
[0022] Also, paddle 200 could include more than two segments with
all or some of the segments folding when inserted into a suitable
tool. Although eight electrodes are shown in FIG. 2, any suitable
number of electrodes could be employed. Additionally, any suitable
pattern of electrodes could be formed. In some embodiments,
multiple (three, four, five, etc.) columns of electrodes are
employed to enable "field steering" which is known in the art to
facilitate selective stimulation of nerve tissues. Also, although
folding is the preferred mechanism to reduce the width of paddle
200 during insertion procedures, other deformations could be
alternatively employed. For example, paddle 200 could be adapted to
"curl" into a cylindrical structure upon entry into the insertion
tool and "uncurl" upon exiting the tool.
[0023] FIG. 3 depicts a flowchart for fabricating paddle 200
according to one representative embodiment. In step 301, a
rectangle or other suitable portion of conductive material is
provided. Although the following discussion only refers to
fabrication of a single paddle 200, multiple paddles can be
fabricated in parallel on suitably sized portion of conductive
material according to the present invention. The conductive
material can be medical grade stainless steel, platinum iridium,
and/or the like. The thickness of the conductive material is
selected to allow the conductive material to be relatively flexible
while possessing a degree of memory or spring characteristic. In
one embodiment, the thickness of the conductive material is
selected to equal approximately 25.4 microns (1 mil).
[0024] In step 302, a coating of urethane (or a similar polymer) is
spin coated on one side of the conductive material for the purpose
of achieving a surface with greater adhesive qualities. In step
303, a urethane film (or any other suitable biocompatible polymer)
is applied to the same side as the spin coat and is laminated to
the conductive material. The urethane film and coating provide an
insulative layer to electrically isolate the conductive material.
The urethane film preferably has a thickness of preferably 25.4 to
152.4 microns (one to six mils).
[0025] In step 304, the paddle form is created by scribing the
paddle form in the conductive material using a suitable laser
(e.g., a programmable YAG laser system). A separate strip or
"feature" of conductive material is defined in a pattern definition
for each electrode that extends from a respective connector element
206 (shown collectively as 206-1 through 206-8 in FIG. 2) to the
area where the corresponding electrode will be formed (as will be
discussed below). In addition to defining the conductive paths, the
laser scribing defines the guide structures that facilitate the
self-folding functionality of paddle 200. It shall be appreciated
that the guide structures (as well as any structure providing
spring-like properties) need not be conductive.
[0026] The pattern definition is preferably provided to a
programmable laser system. The programmable laser system then
applies pulses of energy according to the defined pattern to ablate
the conductive material between each strip of conductive material.
The application of laser pulses is controlled to ablate the
conductive material at the defined locations without cutting
completely through the urethane film behind the ablated conductive
material. The lamination between the urethane film and the
conductive material holds the separate strips or features of
conductive material at the defined locations. Also, upon completion
of the application of laser pulses to paddle 200, each strip of
conductive material is electrically isolated from every other strip
or feature due to the laser scribed separations between them and
the insulative characteristic of the urethane film. In an
alternative embodiment, photo-etching techniques could be employed
to create the paddle form. For example, the paddle form could be
created using a photoresist and chemical etching in lieu of laser
scribing. In another alternative embodiment, micro-printing is
employed to create the paddle form.
[0027] In step 305, a spin coat of urethane is applied over the
conductive material on the side opposite to the urethane laminate
layer. The coating of the urethane material electrically insulates
the top of paddle 200. In step 306, electrodes 203 are defined by
removing the urethane material of the applied coating at the
respective locations thereby exposing the conductive material at
those locations. The removal of the urethane material may occur
using the programmable laser. Alternatively, a separate CO.sub.2
laser could be utilized for exposure of the conductive material
and/or masked plasma etching. In step 307, connector elements 206
are exposed on one or both sides of paddle 200.
[0028] After the completion of paddle 200 according to the
flowchart of FIG. 3, paddle 200 is ready to be mechanically
integrated with and electrically coupled to a medical lead. To
provide electrical connections between an implantable pulse
generator and electrodes 203 of paddle 200, the medical lead
provides a plurality of conductors (e.g., wires) which are
typically spirally wound around a mandrel. Each conductor is
contained within an insulative material to ensure that the
plurality of conductors are electrically isolated from each other.
Also, the plurality of conductors are typically enclosed within a
protective flexible body of biocompatible and biostable polymer. On
a proximal end of the medical lead, a plurality of terminals are
provided for coupling a pulse generator device to the various
conductors.
[0029] On the distal end of a medical lead, openings in the outer
body and in the insulative coating of the conductors are made at
suitable locations. Conductive material can be provided within the
openings to provide an electrical path from the conductors to the
surface of the lead. The exposed connector elements 206 of paddle
200 are preferably coupled to the lead conductors at these
locations to create the electrical connection between the
conductors of the lead and electrodes 203. Alternatively, a wire
connection could be employed between each conductor of the lead and
a respective connector element 206. Additional details regarding
specific medical leads and lead fabrication methods are available
in U.S. Pat. No. 6,216,045 entitled "Implantable lead and method of
manufacture," which is incorporated herein by reference. It shall
be appreciated that paddle designs according to the present
invention can be implemented with any type of suitable medical
lead.
[0030] FIG. 4A depicts a cross-sectional view of paddle lead
assembly 400 according to one representative embodiment. Medical
lead 410 is shown at the bottom of the assembly. Block 420 is
utilized to facilitate the lead assembly process and as shown in
FIG. 4A, is affixed to medical lead 410. Block 420 can be
implemented using an extrusion of bio-compatible polymer. Block 420
could also be implemented as an injection molded structure. Paddle
200 is coupled to block 420. Block 420 may optionally include
recess 430 that facilitates the folding of segment 210. It shall be
appreciated that other shapes and designs could be employed for
block 420. Also, in an alternative embodiment, paddle 200 could be
directly attached to a stimulation lead.
[0031] One advantage of assembly 400 is the minimization of volume
displacement associated with the folding and unfolding of the
paddle. Reference is made to FIG. 7 for comparison, where foldable
lead 700 folds in a manner similar to turning pages in a book. As
shown in FIG. 7, this type of folding requires free space 750 to
accomplish the folding and unfolding. Specifically, if foldable
lead 700 were inserted into the epidural space of a patient, space
750 must be free of tissue to allow foldable lead 700 to unfold.
However, assembly 400 is adapted to fold in a different manner that
requires significantly less volume displacement. Recess 430 and the
slit 204 enables portion 210 of paddle 200 to fold over portion 220
in a "sliding" or substantially lateral manner. Slit 204 provides a
degree of flexibility to the paddle and recess 430 guides portion
210 during the folding process. As shown in the progression of
FIGS. 4B through 4D, the upward displacement of portion 210 of
paddle 200 during folding (and, similarly, during unfolding) is
relatively minimal. That is, a "bend" develops in portion 210 which
is moved across the portion of the paddle 200 during the folding
and unfolding process. Accordingly, assembly 400 can be unfolded
within a much smaller volume than foldable lead 700.
[0032] FIGS. 5A-5H depict various steps of a method for placement
of a paddle lead within the epidural space of a patient according
to one representative embodiment. As shown in FIG. 5A, an epidural
needle is inserted into the epidural space. The initial insertion
of the epidural needle typically occurs an angle that is offset
relative to the spinal column. Also, the location for insertion of
the needle is typically two to five vertebrae below the spinal
tissue associated with the pain to be treated by the electrical
neuromodulation. Using fluoroscopic guidance, a guide wire is
inserted with the stylet slightly withdrawn as shown in FIG. 5B.
Once the tip of the guide wire is fully within the epidural space
and slightly beyond the distal tip of the needle, the stylet is
fully re-inserted and the guide wire is advanced to the desired
target location as shown in FIG. 5C.
[0033] As shown in FIG. 5D, the needle is removed using the
"hold-and-push" technique leaving the guide wire in the epidural
space. The insertion tool 500 is inserted over the proximal end of
the guide wire and advanced into the epidural space under
fluoroscopy to appropriate position (FIG. 5E) and the guide wire is
removed. For the purpose of the present application, an insertion
tool refers to any catheter-like structure, having a lumen or an
open channel, that can be inserted between the vertebrae into the
epidural space without a partial laminectomy. The insertion tool
may or may not comprise a sharp distal end. The insertion tool
preferably expands the tissue surrounding the guide wire thereby
enabling the insertion of the paddle lead. In practice, the
insertion tool is preferably a flexible hollow plastic tube. The
flexibility of the tube accommodates an offset insertion angle into
the vertebrae used for the initial insertion of the epidural
needle. An example of an introduction tool can be found in U.S.
Patent Publication No. 20050288758A1, which is incorporated herein
by reference. If appropriate, a segment of the epidural space could
be opened to accommodate paddle 200 (step not shown). For example,
a cutting tool (e.g., having dual blades or scissor-like elements)
could be advanced through insertion tool 500 to open tissue to
allow paddle 200 to be received and unfolded.
[0034] The distal end of paddle 200 of lead assembly 400 is
inserted within insertion tool 500 as shown in FIG. 5F. Preferably,
a guide wire is inserted within the lumen of the lead coupled to
paddle 200 to facilitate the advancement of the lead and paddle.
The contact of paddle 200 with the interior of insertion tool 500
causes paddle 200 to fold upon itself thereby fitting paddle 200
within the insertion tool as shown in FIG. 5G. Paddle 200 is
advanced through insertion tool 500 by advancing lead body 410 as
shown in FIG. 5H. When paddle 200 exits insertion tool 500, paddle
200 resumes its extended state to expose electrodes 203 to the
target spinal tissue for stimulation. In an alternative embodiment,
the lead could be mated to the insertion tool using a suitable
mating component and the lead could be advanced concurrently with
the placement of the insertion tool.
[0035] FIG. 6 depicts foldable paddle lead 400 coupled to
implantable pulse generator (IPG) 600 according to one
representative embodiment. An example of a commercially available
IPG is the Eon.RTM. Rechargeable IPG available from Advanced
Neuromodulation Systems, Inc. As shown in FIG. 6, paddle lead 400
is coupled to one of the headers 610 of generator 600. Each header
610 electrically couples to a respective lead 410 or an extension
lead. Also, each header 610 electrically couples to internal
components contained within the sealed portion 620 of IPG 600. The
sealed portion 620 contains the pulse generating circuitry,
communication circuitry, control circuitry, and battery (not shown)
within an enclosure to protect the components after implantation
within a patient. The control circuitry controls the pulse
generating circuitry to apply varying pulses to the patient via
electrodes 203 of paddle 200 according to multiple parameters
(e.g., amplitude, pulse width, frequency, etc.). The parameters are
set by an external programming device (not shown) via wireless
communication with IPG 600.
[0036] Although some representative embodiments have been discussed
in terms of neurostimulation applications, alternative
representative embodiments could be employed for other medical
applications. For example, in one alternative embodiment, a paddle
structure could be adapted for any suitable type of cardiac
stimulation such as defibrillation and pacing. The paddle structure
could be inserted through the vascular system of the patient using
a suitable catheter and introduced within a suitable cardiac
region. The paddle structure then could be adapted to unfold upon
exiting the catheter to contact the cardiac tissue to be
stimulated. In other alternative embodiments, the paddle could be
utilized for cardiac mapping and/or tissue ablation.
[0037] Some representative embodiments may provide a number of
advantages. Some representative embodiments provide a paddle that
can be inserted into and removed from the epidural space of a
patient without requiring a partial laminectomy. Furthermore, some
representative embodiments provide a method of fabricating a paddle
design that is highly repeatable and efficient. The fabrication
method further does not necessarily require the use of any overly
caustic chemicals.
[0038] Although representative embodiments and advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the appended claims. Moreover, the
scope of the present application is not intended to be limited to
the particular embodiments of the process, machine, manufacture,
composition of matter, means, methods and steps described in the
specification. As one of ordinary skill in the art will readily
appreciate from this disclosure, processes, machines, manufacture,
compositions of matter, means, methods, or steps, presently
existing or later to be developed that perform substantially the
same function or achieve substantially the same result as the
corresponding embodiments described herein may be utilized without
departing from the scope of the appended claims. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
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