U.S. patent application number 15/131848 was filed with the patent office on 2016-08-11 for implantable flexible circuit leads and methods of use.
The applicant listed for this patent is Albert G. Burdulis, Matthew G. Hills, Mir A. Imran, Eyad Kishawi. Invention is credited to Albert G. Burdulis, Matthew G. Hills, Mir A. Imran, Eyad Kishawi.
Application Number | 20160228696 15/131848 |
Document ID | / |
Family ID | 39493085 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160228696 |
Kind Code |
A1 |
Imran; Mir A. ; et
al. |
August 11, 2016 |
IMPLANTABLE FLEXIBLE CIRCUIT LEADS AND METHODS OF USE
Abstract
Devices, systems and methods are provided for stimulation of
tissues and structures within a body of a patient. In particular,
implantable leads are provided which are comprised of a flexible
circuit. Typically, the flexible circuit includes an array of
conductors bonded to a thin dielectric film. Example dielectric
films include polyimide, polyvinylidene fluoride (PVDF) or other
biocompatible materials to name a few. Such leads are particularly
suitable for stimulation of the spinal anatomy, more particularly
suitable for stimulation of specific nerve anatomies, such as the
dorsal root (optionally including the dorsal root ganglion).
Inventors: |
Imran; Mir A.; (Los Altos,
CA) ; Burdulis; Albert G.; (San Francisco, CA)
; Hills; Matthew G.; (Los Altos, CA) ; Kishawi;
Eyad; (San Mateo, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Imran; Mir A.
Burdulis; Albert G.
Hills; Matthew G.
Kishawi; Eyad |
Los Altos
San Francisco
Los Altos
San Mateo |
CA
CA
CA
CA |
US
US
US
US |
|
|
Family ID: |
39493085 |
Appl. No.: |
15/131848 |
Filed: |
April 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11952062 |
Dec 6, 2007 |
9314618 |
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15131848 |
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60873459 |
Dec 6, 2006 |
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60873496 |
Dec 6, 2006 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/0556 20130101;
H05K 1/118 20130101; A61N 1/0553 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1. A method for stimulating a tissue within a body comprising:
positioning a lead comprising a flexible circuit having at least
one electrode so that at least one of the at least one electrode is
disposed near a dorsal root; and supplying electrical energy to the
at least one of the at least one electrode so as to stimulate at
least a portion of the dorsal root.
2. A method of claim 1, wherein the portion of the dorsal root
comprises a dorsal root ganglion.
3. A method of claim 1, further comprising advancing the lead
through a foremen.
4. A method of claim 1, further comprising advancing the lead
through an epidural space.
5. A method of claim 1, further comprising joining the lead with an
implantable pulse generator.
6. A method of claim 5, further comprising implanting the lead and
the implantable pulse generator wholly within the body.
7. A flexible circuit lead for stimulating a body tissue
comprising: an elongate structure having a distal end configured to
be positioned near a dorsal root and a proximal end coupleable with
a pulse generator, wherein the structure comprises a dielectric
film; at least one electrode disposed near the distal end; and at
least one conductive trace extending from the at least one
electrode toward the proximal end so that stimulation energy is
transmittable from the coupled pulse generator to the at least one
electrode so as to stimulate the at least a portion of the dorsal
root.
8. A flexible circuit lead as in claim 7, wherein the at least one
electrode is comprised of a biocompatible conductive metal, alloy
or combination of these plated onto the dielectric film.
9. A flexible circuit lead as in claim 8, wherein the biocompatible
conductive metal, alloy or combination includes gold, titanium,
tungsten, titanium tungsten, titanium nitride, platinum, iridium or
platinum-iridium alloy.
10. A flexible circuit lead as in claim 7, wherein the dielectric
film has a thickness in the range of approximately 7.5 to 125
.mu.m.
11. A flexible circuit lead as in claim 7, wherein the at least one
electrode comprises a plurality of electrodes arranged
substantially linearly along a longitudinal axis of the distal
end.
12. A flexible circuit lead as in claim 7, wherein the at least one
electrode comprises a plurality of electrodes arranged
substantially linearly along a horizontal axis of the distal
end.
13. A flexible circuit lead as in claim 7, wherein the at least one
electrode comprises a plurality of electrodes arranged in a
substantially circular or arc shape.
14. A flexible circuit lead as in claim 7, wherein the distal end
has a pronged shape including at least two prongs.
15. A flexible circuit lead as in claim 8, wherein one of the at
least one electrodes is disposed near a tip of one of the at least
two prongs.
16. A flexible circuit lead as in claim 7, wherein the distal end
is configured to wrap around the body tissue.
17. A flexible circuit lead as in claim 7, wherein the distal end
of the elongate structure is passable through a needle.
18. A lead for stimulating a body tissue comprising: an elongate
structure having a proximal end coupleable with a pulse generator
and a distal end having two edges which are capable of being
positioned in opposition, wherein the distal end includes at least
two electrodes which generally oppose each other when the edges are
positioned in opposition so as to stimulate the body tissue.
19. A lead as in claim 18, wherein the distal end forms a V-shape
or U-shape when the two edges are positioned in opposition which
allows the body tissue to be positioned at least partially within
the V-shape or U-shape.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/952,062, filed Dec. 6, 2007, which claims
priority of U.S. Provisional Patent Application No. 60/873,459,
filed Dec. 6, 2006 (Atty. Docket No. 10088-702.101); and U.S.
Provisional Patent Application No. 60/873,496, filed Dec. 6, 2006
(Atty. Docket No. 10088-704.101), both of which are incorporated
herein by reference for all purposes.
BACKGROUND
[0002] The application of specific electrical energy to the spinal
cord for the purpose of managing pain has been actively practiced
since the 1960s. It is known that application of an electrical
field to spinal nervous tissue can effectively mask certain types
of pain transmitted from regions of the body associated with the
stimulated nervous tissue. Such masking is known as paresthesia, a
subjective sensation of numbness or tingling in the afflicted
bodily regions. Application of electrical energy has been based on
the gate control theory of pain. Published in 1965 by Melzack and
Wall, this theory states that reception of large nerve fiber
information, such as touch, sense of cold, or vibration, would turn
off or close the gate to reception of painful small nerve fiber
information. The expected end result would, therefore, be pain
relief. Based on the gate control theory, electrical stimulation of
large fibers of the spinal cord cause small fiber information to be
reduced or eliminated at that spinal segment and all other
information downstream from that segment would be reduced or
eliminated as well. Such electrical stimulation of the spinal cord,
once known as dorsal column stimulation, is now referred to as
spinal cord stimulation or SCS.
[0003] FIGS. 1A-1B illustrate conventional placement of an SCS
system 10. Conventional SCS systems include an implantable power
source or implantable pulse generator (IPG) 12 and an implantable
lead 14. Such IPGs 12 are similar in size and weight to pacemakers
and are typically implanted in the buttocks of a patient P. Using
fluoroscopy, the lead 14 is implanted into the epidural space E of
the spinal column and positioned against the dura layer D of the
spinal cord S, as illustrated in FIG. 1B. The lead 14 is implanted
either through the skin via an epidural needle (for percutaneous
leads) or directly and surgically through a mini laminotomy
operation (for paddle leads).
[0004] FIG. 2 illustrates example conventional paddle leads 16 and
percutaneous leads 18. Paddle leads 16 typically have the form of a
slab of silicon rubber having one or more electrodes 20 on its
surface. Example dimensions of a paddle lead 16 is illustrated in
FIG. 3. Percutaneous leads 18 typically have the form of a tube or
rod having one or more electrodes 20 extending therearound. Example
dimensions of a percutaneous lead 18 is illustrated in FIG. 4.
[0005] Implantation of a percutaneous lead 18 typically involves an
incision over the low back area (for control of back and leg pain)
or over the upper back and neck area (for pain in the arms). An
epidural needle is placed through the incision into the epidural
space and the lead is advanced and steered over the spinal cord
until it reaches the area of the spinal cord that, when
electrically stimulated, produces a comfortable tingling sensation
(paresthesia) that covers the patient's painful area. To locate
this area, the lead is moved and turned on and off while the
patient provides feedback about stimulation coverage. Because the
patient participates in this operation and directs the operator to
the correct area of the spinal cord, the procedure is performed
with local anesthesia.
[0006] Implantation of paddle leads 16 typically involves
performing a mini laminotomy to implant the lead. An incision is
made either slightly below or above the spinal cord segment to be
stimulated. The epidural space is entered directly through the hole
in the bone and a paddle lead 16 is placed over the area to
stimulate the spinal cord. The target area for stimulation usually
has been located before this procedure during a spinal cord
stimulation trial with percutaneous leads 18.
[0007] Although such SCS systems have effectively relieved pain in
some patients, these systems have a number of drawbacks. To begin,
as illustrated in FIG. 5, the lead 14 is positioned upon the spinal
cord dura layer D so that the electrodes 20 stimulate a wide
portion of the spinal cord and associated spinal nervous tissue.
The spinal cord is a continuous body and three spinal levels of the
spinal cord are illustrated. For purposes of illustration, spinal
levels are sub-sections of the spinal cord S depicting that portion
where the dorsal root DR and ventral root VR join the spinal cord
S. The peripheral nerve N divides into the dorsal root DR and the
dorsal root ganglion DRG and the ventral nerve root VR each of
which feed into the spinal cord S. An ascending pathway 17 is
illustrated between level 2 and level 1 and a descending pathway 19
is illustrated from level 2 to level 3. Spinal levels can
correspond to the vertebral levels of the spine commonly used to
describe the vertebral bodies of the spine. For simplicity, each
level illustrates the nerves of only one side and a normal
anatomical configuration would have similar nerves illustrated in
the side of the spinal cord directly adjacent the lead.
[0008] Motor spinal nervous tissue, or nervous tissue from ventral
nerve roots, transmits muscle/motor control signals. Sensory spinal
nervous tissue, or nervous tissue from dorsal nerve roots,
transmits pain signals. Corresponding dorsal and ventral nerve
roots depart the spinal cord "separately"; however, immediately
thereafter, the nervous tissue of the dorsal and ventral nerve
roots are mixed, or intertwined. Accordingly, electrical
stimulation by the lead 14 often causes undesirable stimulation of
the motor nerves in addition to the sensory spinal nervous
tissue.
[0009] Because the electrodes span several levels the generated
stimulation energy 15 stimulates or is applied to more than one
type of nerve tissue on more than one level. Moreover, these and
other conventional, non-specific stimulation systems also apply
stimulation energy to the spinal cord and to other neural tissue
beyond the intended stimulation targets. As used herein,
non-specific stimulation refers to the fact that the stimulation
energy is provided to all spinal levels including the nerves and
the spinal cord generally and indiscriminately. Even if the
epidural electrode is reduced in size to simply stimulate only one
level, that electrode will apply stimulation energy
Indiscriminately to everything (i.e. all nerve fibers and other
tissues) within the range of the applied energy. Moreover, larger
epidural electrode arrays may after cerebral spinal fluid flow thus
further altering local neural excitability states.
[0010] Another challenge confronting conventional neurostimulation
systems is that since epidural electrodes must apply energy across
a wide variety of tissues and fluids (i.e. CSF fluid amount varies
along the spine as does pia mater thickness) the amount of
stimulation energy needed to provide the desired amount of
neurostimulation is difficult to precisely control. As such,
increasing amounts of energy may be required to ensure sufficient
stimulation energy reaches the desired stimulation area. However,
as applied stimulation energy increases so too increases the
likelihood of deleterious damage or stimulation of surrounding
tissue, structures or neural pathways.
[0011] Improved stimulation devices, systems and methods are
desired that enable more precise and effective delivery of
stimulation energy. Such devices should be reliably manufactural,
appropriately sized, cost effective and easy to use. At these some
of these objectives will be fulfilled by the present invention.
SUMMARY
[0012] The present invention provides devices, systems and methods
for stimulation of tissues and structures within a body of a
patient. In particular, implantable leads are provided which are
flexible, reliable and easily manufacturable for a variety of
medical applications. Such leads are particularly suitable for
stimulation of the spinal anatomy, more particularly suitable for
stimulation of specific nerve anatomies, such as the dorsal root
(optionally including the dorsal root ganglion). Such specificity
is enhanced by the design attributes of the leads.
[0013] The implantable leads of the present invention utilize a
flexible circuit. Typically, the flexible circuit includes an array
of conductors bonded to a thin dielectric film. Example dielectric
films include polyimide, polyvinylidene fluoride (PVDF) or other
biocompatible materials to name a few. The conductors are comprised
of biocompatible conductive metal(s) and/or alloy(s), such as gold,
titanium, tungsten, titanium tungsten, titanium nitride, platinum,
iridium, or platinum-iridium alloy, which is plated onto the
dielectric film. The base and metal construct is then etched to
form a circuit (i.e. an electrode pad contact and a "trace" to
connect the pad to a connector). In some embodiments, redundancy in
the "traces" is provided by utilizing multiple traces to the same
contact to improve reliability.
[0014] Some advantages of leads comprised of a flexible circuit
over traditional leads are greater reliability, size and weight
reduction, elimination of mechanical connectors, elimination of
wiring errors, increased impedance control and signal quality,
circuit simplification, greater operating temperature range, and
higher circuit density. In addition, lower cost is another
advantage of using flexible circuits. In some embodiments, the
entire lead will be formed from a flexible circuit. Also, in some
embodiments, the lead will include an integrated connector for
connection to an electronics package.
[0015] One main advantage of the flexible circuitry lead is its
thinness and therefore flexibility. The thickness of the dielectric
film typically ranges from 7.5 to 125 .mu.m (0.3 to 5 mils).
However, in some embodiments, the lead will be comprised of a
flexible circuit having a base layer of 0.5 to 2 mils thick.
[0016] The flexible circuitry used in the present invention may be
single-sided, double-sided, or multilayer. Single-sided circuits
are comprised of a single conductive layer and are the simplest
type of flexible circuit. In some instances, a technique known as
back baring or double access may be used to create a special type
of single layer circuit. This technique allows access to the metal
conductors from both sides of the circuit and is used when
component soldering or other interconnection is desired on two
sides of the circuit.
[0017] Double-sided circuits, as the name implies, are circuits
with two conductive layers that are usually accessible from both
sides. Multilayer refers to two or more layers which have been
stacked and bonded.
[0018] In some embodiments, the flexible circuit is created with
methods of the present invention. For example, metal deposition,
such as vapor deposition, sputtering techniques or plasma fields,
is used to coat the film structure with metal to form the
electrodes and traces. In such embodiments, the film structure is
comprised of polyvinylidene fluoride (PVDF). The process may
utilize PVDF in either sheet form or, preferably, in roll form,
with cooling to reduce thermal stresses between the dielectric film
structure and the metal coat. The PVDF is coated with an adhesion
layer, such as titanium or titanium-tungsten alloy, which will
improve the reliability of the bond between the dielectric film
structure and the electrodes and traces that will be deposited
thereon. The adhesion layer is then coated, such as sputter coated,
with a seed layer of conductive biocompatible metal, such as gold
or platinum. After such metallization, the seed layer is patterned,
either by photolithography and wet etch, or by laser ablation to
form the shapes of the traces and electrodes. After patterning the
seed layer of metal, sputtering or electroplating is used to
increase the thickness of the traces in order to improve
conductivity, and then again to create the final electrode working
surface. Possible trace materials include platinum, gold,
iridium-oxide, a combination thereof or any other conductive
biocompatible metal suitable for implantation. The electrode
surface may be coated over the entire metallization of the lead, or
selectively and only over the intended electrode surface with an
inert metal such as platinum, iridium-oxide, or combination
thereof. In some embodiments, the adhesion layer of titanium or
titanium-tungsten alloy is sputter coated with a seed layer of
gold, then sputter coated with platinum and then electroplated with
platinum. In other embodiments, the adhesion layer of titanium or
titanium-tungsten alloy is sputter coated with a seed layer of
gold, then electroplated with gold and then electroplated with
platinum. In yet other embodiments, the adhesion layer of titanium
or titanium-tungsten alloy is sputter coated with a seed layer of
platinum, then electroplated with platinum. It may be appreciated
that other combinations may also be used.
[0019] In a first aspect of the present invention, a method is
provided for stimulating a tissue within a body. In some
embodiments, the method comprises positioning a lead comprising a
flexible circuit having at least one electrode so that at least one
of the at least one electrode is disposed near a dorsal root.
Optionally, the positioning ensures that at least one of the at
least one electrode is disposed near a dorsal root ganglion of the
dorsal root. The method also includes supplying electrical energy
to the at least one of the at least one electrode so as to
stimulate at least a portion of the dorsal root. In some
embodiments, the portion of the dorsal root comprises a dorsal root
ganglion.
[0020] Optionally, the method may include advancing the lead
through a foramen and/or advancing the lead through an epidural
space. Typically, the method further comprises joining the lead
with an implantable pulse generator. In such instances, the method
typically includes implanting the lead and the implantable pulse
generator wholly within the body.
[0021] In a second aspect of the present invention, a flexible
circuit lead is provided for stimulating a body tissue. In some
embodiments, the lead comprises an elongate structure having a
distal end configured to be positioned near a dorsal root and a
proximal end coupleable with a pulse generator, wherein the
structure comprises a dielectric film. The lead also includes at
least one electrode disposed near the distal end and at least one
conductive trace extending from the at least one electrode toward
the proximal end so that stimulation energy is transmittable from
the coupled pulse generator to the at least one electrode so as to
stimulate the at least a portion of the dorsal root.
[0022] In some embodiments, the at least one electrode is comprised
of a biocompatible conductive metal, alloy or combination of these
plated onto the dielectric film. In such instances, the
biocompatible conductive metal, alloy or combination may include
gold, titanium, tungsten, titanium tungsten, titanium nitride,
platinum, iridium or platinum-iridium alloy. Often, the dielectric
film has a thickness in the range of approximately 7.5 to 125
.mu.m.
[0023] In some embodiments, the at least one electrode comprises a
plurality of electrodes arranged substantially linearly along a
longitudinal axis of the distal end. In other embodiments, the at
least one electrode comprises a plurality of electrodes arranged
substantially linearly along a horizontal axis of the distal end.
Optionally, the at least one electrode comprises a plurality of
electrodes arranged in a substantially circular or arc shape.
[0024] In some instances, the distal end has a pronged shape
including at least two prongs. In such instances, one of the at
least one electrodes may be disposed near a tip of one of the at
least two prongs. In some embodiments, the distal end is configured
to wrap around the body tissue. And typically, the distal end of
the elongate structure is passable through a needle.
[0025] In a third aspect of the present invention, a lead is
provided for stimulating a body tissue comprising: an elongate
structure having a proximal end coupleable with a pulse generator
and a distal end having two edges which are capable of being
positioned in opposition, wherein the distal end includes at least
two electrodes which generally oppose each other when the edges are
positioned in opposition so as to stimulate the body tissue.
Typically the body tissue comprises a dorsal root ganglion.
[0026] In some embodiments, the distal end forms a V-shape or
U-shape when the two edges are positioned in opposition which
allows the body tissue to be positioned at least partially within
the V-shape or U-shape. The distal end may comprise two elongate
elements, each element having one of the two edges. In such
instances, the two elongate elements may be positionable in linear
alignment with a longitudinal axis of the elongate structure.
[0027] In some embodiments, the distal end has a rounded shape
wherein sides of the rounded shape form the two edges. In such
embodiments, the sides of the rounded shape may curl or fold
towards each other to position the two edges in opposition.
[0028] Typically, the elongate structure comprises a dielectric
film. The dielectric film may have a thickness in the range of
approximately 7 to 125 .mu.m. Also, the at least two electrodes may
be comprised of a biocompatible conductive metal, alloy or
combination of these plated on the dielectric film. Typically, the
distal end is passable through a needle.
[0029] In another aspect of the present invention, a system for
stimulating a body tissue is provided comprising: a first elongate
structure having first proximal end coupleable with a pulse
generator and a first distal end, wherein the first distal end has
a first inner surface having a first electrode disposed thereon,
and a second elongate structure having a second proximal end
coupleable with the pulse generator and a second distal end,
wherein the second distal end has a second inner surface having a
second electrode disposed thereon. The first and second elongate
structures are joined so that the first and second electrodes are
capable of directing stimulation energy toward each other, and
wherein the first and second distal ends are moveable away from
each other so as to allow the body tissue to be positioned at least
partially therebetween to receive the stimulation energy.
[0030] In some embodiments, the first and second elongate
structures are slidably joined. Optionally, the first distal end is
movable by recoil force. In some systems, the first distal end is
attachable to a first obturator which is capable of moving the
first distal end. In these systems, the first obturator may be
configured to dissect tissue while it moves the first distal end.
Optionally, the first obturator may be advanceable from a delivery
device so as to advance the first distal end and move the first
distal end away from the second distal end.
[0031] Typically, the first elongate structure comprises a
dielectric film. And, typically, the body tissue comprises a dorsal
root ganglion. Optionally, the distal end may be passable through a
needle.
[0032] In some embodiments, the first elongate structure includes a
first contact pad disposed on an outer surface of the proximal end
of the first elongate structure, wherein the first contact pad
provides electrical connection from the first electrode to the
pulse generator. And in some embodiments, the second elongate
structure includes a second contact pad disposed on an outer
surface of the proximal end of the second elongate structure,
wherein the second contact pad provides electrical connection from
the second electrode to the pulse generator.
[0033] In another aspect of the present invention, a flexible
circuit lead is provided for stimulating a body tissue, wherein the
lead comprises an elongate structure having a distal end comprising
at least one electrode on a dielectric film, and wherein the distal
end is movable to at least partially surround the body tissue and
direct stimulation energy from the at least one electrode toward
the body tissue. Typically, the distal end is passable through a
needle.
[0034] In some embodiments, the distal end is moveable by curling
or uncurling so as to at least partially surround the body tissue.
In other embodiments, the distal end is moveable by folding or
unfolding so as to at least partially surround the body tissue.
[0035] Typically, the distal end comprises opposing elements which
move toward or away from each other so as to at least partially
surround the body tissue. In some instances, the opposing elements
may move independently. Optionally, the opposing elements may form
a V-shape.
[0036] In another aspect of the present invention, a device is
provided for stimulating a body tissue, wherein the device
comprises an elongate shaft having an outer surface and a lead
having a at least one electrode, wherein the lead is mounted on the
outer surface of the elongate shaft so that the at least one
electrode is positionable near a dorsal root for stimulation.
Typically, the lead is comprised of an elongate structure
comprising a dielectric film. In such instances, the at least one
electrode may be comprised of a biocompatible conductive metal,
alloy or combination of these plated onto the dielectric film.
[0037] In some embodiments, the elongate shaft includes a lumen
therethrough configured for passage of a stylet. In some
embodiments, the at least one electrode comprises a plurality of
electrodes positioned so as to wrap at least partially around the
elongate shaft. And in some embodiments, the elongate shaft is
configured for implantation in an arrangement so that the at least
one electrode is positioned near a dorsal root ganglion.
[0038] In yet another aspect of the present invention, a lead is
provided for stimulating a body tissue, wherein the lead comprises
a first elongate structure having a first distal end configured to
be positioned near the body tissue and a first proximal end
coupleable with a pulse generator. The first elongate structure has
a first electrode disposed near the first distal end. The lead also
includes a second elongate structure having a second distal end, a
second proximal end and a second electrode disposed near the second
distal end. The second elongate structure is attached to the first
elongate structure in a layered configuration so that stimulation
energy is transmittable from the coupled pulse generator to the
first and second electrode so as to stimulate the body tissue.
[0039] In some embodiments, the layered configuration offsets the
distal ends. In some embodiments, the first and second electrodes
are arranged substantially linearly along a longitudinal axis of
the distal end.
[0040] In some instances, the lead further comprises a third
elongate structure having a third proximal end, a third distal end
and a third electrode disposed near the third distal end, wherein
the third elongate structure is attached to the second elongate
structure in a layered configuration so that stimulation energy is
transmittable from the coupled pulse generator to the third
electrode so as to stimulate the body tissue. Typically, the distal
ends of the layered configuration of elongate structures are
passable through a needle.
[0041] In some embodiments, the at least one conductive trace
extends from each electrode toward its respective proximal end. In
such embodiments, each conductive trace may have a shape so that
the layered configuration balances the conductive traces. At least
one of the at least one conductive traces may have a zig-zag or
serpentine shape.
[0042] Typically, the first elongate structure comprises a
dielectric film. In such instances, the first electrode is
comprised of a biocompatible conductive metal, alloy or combination
of these plated onto the dielectric film. Optionally, the
biocompatible conductive metal, alloy or combination includes gold,
titanium, tungsten, titanium tungsten, titanium nitride, platinum,
iridium or platinum-iridium alloy.
[0043] Other objects and advantages of the present invention will
become apparent from the detailed description to follow, together
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1A-1B, 2, 3, 4, 5 illustrate prior art.
[0045] FIG. 6, 6A, 6B illustrates an embodiment of a flexible
circuit lead of the present invention.
[0046] FIGS. 7A, 7B, 7C, 7D illustrate a variety of approaches to
an example target anatomy for positioning the leads of the present
invention.
[0047] FIG. 8 illustrates electrodes positioned more proximal to
the distal tip of the lead.
[0048] FIG. 9 illustrates a distal end of an embodiment of a
flexible circuit lead of the present invention.
[0049] FIG. 10 illustrates a proximal end of an embodiment of a
flexible circuit lead of the present invention
[0050] FIGS. 11A-11B illustrate a layered lead comprising two or
more individual leads which are layered and bonded together.
[0051] FIG. 12 illustrates an embodiment of a layered lead in an
expanded view.
[0052] FIGS. 13, 13A, 13B illustrates an example of a lead which
may be used in layering.
[0053] FIG. 14 illustrates an example process and fixture for
forming a layered lead.
[0054] FIG. 15A illustrates a lead of the present invention having
an oval, rounded or circular distal end.
[0055] FIG. 15B illustrates the lead of FIG. 15A positioned so that
its distal end is in proximity to a dorsal root ganglion.
[0056] FIGS. 16A, 16B, 16C illustrate a distal end of a lead which
is curlable or rollable.
[0057] FIG. 17 illustrates a lead of the present invention having a
pronged distal end.
[0058] FIG. 18 illustrates the lead of FIG. 17 positioned so that
its distal end is in proximity to a dorsal root ganglion.
[0059] FIGS. 19-20 illustrate an embodiment of a shaped flexible
circuit lead which can form a three dimensional shape.
[0060] FIG. 21A-21B illustrate a delivery device comprises a
flattened tube having a distal end and a pair of obturators which
are advanceable out of the distal end.
[0061] FIG. 22 illustrates a flexible circuit lead attached to a
delivery device.
[0062] FIG. 23 illustrates a flexible circuit lead particularly
suited for wrapping around a catheter.
[0063] FIGS. 24-25 illustrate an example connector of the present
invention.
DETAILED DESCRIPTION
[0064] FIG. 6 illustrates an embodiment of a lead 100 of the
present invention. The lead 100 is comprised of a flexible circuit.
In particular, the lead 100 is comprised of an elongate structure
107 having a distal end 102 and a proximal end 104. The distal end
102 is configured to be positioned near a target body tissue and
the proximal end 104 is coupleable with a power source or
implantable pulse generator (IPG). FIG. 6A provides a detailed
illustration of the distal end 102 of the lead 100 of FIG. 6. As
shown, the lead 100 includes at least one electrode 106 plated on
the dielectric film. In this embodiment, four electrodes 106 are
present in an array. It may be appreciated that any number of
electrodes 106 may be used in any desired arrangement, including
longitudinally aligned individually (as shown) or in pairs or sets.
FIG. 6B provides a detailed illustration of the proximal end 104 of
the lead 100 of FIG. 6. The proximal end 104 includes contact pads
108 that are used to connect with the IPG. In this embodiment, four
contact pads 108 are shown, one corresponding to each electrode
106. Each contact pad 108 is electrically connected with an
electrode 106 through a conductive trace 110 that extends
therebetween, thus from the proximal end 104 to the distal end 102.
Stimulation energy is transmitted from the IPG through the contact
pads 108 and through trace 110 to the electrodes 106 which
stimulate the desired target tissue. It may be appreciated that in
some embodiments, the conductive traces 110 are arranged so that
each contact pad 108 is connected with more than one electrode 106
or each electrode 106 is connected with more than one contact pad
108.
[0065] The leads 100 of the present invention may be used to
stimulate a variety of target tissues, particularly a dorsal root
ganglion DRG. FIGS. 7A-7D illustrate various approaches to the DRG
and positioning a lead 100 of the present invention so as to
stimulate the DRG. Embodiments of these approaches include passing
through, near or along one or more posterior or lateral openings in
the bony structure of the spinal column. An example of a posterior
opening is an opening between adjacent spinous processes. An
example of a lateral opening is the foramen or opening at least
partially defined by the articulating processes and the vertebrae.
FIG. 7A illustrates a retrograde (100a), antegrade (100b) and
lateral approach (100c) to the dorsal root and DRG from the spinal
column. FIG. 7B illustrates a retrograde (100d), antegrade (100e)
and lateral approach (100f) to the dorsal root and DRG from outside
of the spinal column, such as from a side or traditional
percutaneous approach. FIG. 7C illustrates an antegrade approach to
a dorsal root and DRG between an articulating process (not shown)
and the vertebral body (not shown). FIG. 7D illustrates a
retrograde approach to a dorsal root and DRG between an
articulating process (not shown) and a vertebral body (not shown).
The leads of the present invention may also be positioned by any
other suitable method or approach. One exemplary retrograde
approach is a retrograde translaminar approach. One exemplary
approach is an antegrade translaminar approach. One exemplary
lateral approach is a transforamenal approach.
[0066] As mentioned above, each lead 100 includes at least one
electrode 106, preferably two, three, four, five, six or more
electrodes. The lead 100 is preferably aligned so that at least one
of the at least one electrodes 160 is positioned as close to the
target location as possible, for example, on the DRG. In some
situations, the DRG has a size of 5-10 mm. Thus, in some
embodiments, a lead 100 having four 1 mm square electrodes spaced
1-2 mm apart would allow all four of the electrodes to
simultaneously contact the DRG. In such an instance, all four
electrodes may provide stimulation energy. In other embodiments,
the electrodes may be sized or shaped so that less than the total
number of electrodes are desirably positioned on or near the target
location. This may also occur due to placement of the lead. In such
instances, a subset of the electrodes may provide stimulation
energy, preferably one or more electrodes positioned closest to the
target location. This assists in reducing or eliminating undesired
stimulation of non-target anatomies.
[0067] It may be appreciated that the electrodes may be positioned
at any location along the length of the lead, may have any suitable
shape and any suitable spacing. FIG. 8 illustrates electrodes 160
positioned more proximal to the distal tip of the lead 100. Thus, a
portion of the lead 100 having no electrodes 160 extends distally
beyond the last electrode 160. When the electrodes 160 are
positioned over the target location, the distal most end of the
lead 100 extends therefrom, such as transforamenally. Such
extension may assist in anchoring the lead. It may be appreciated
that the lead 100 of FIG. 8 may alternatively be positioned by any
of the approaches listed above, or any other approaches.
[0068] FIG. 9 illustrates a distal end 102 of another embodiment of
a flexible circuit lead 100 of the present invention. In this
embodiment, three electrodes 106 are disposed in an array on the
film structure 107, each electrode 106 having a trace 110 which
extends toward the proximal end 104 of the lead. In this
embodiment, the lead 100 also includes an anchoring feature 118
which assists in anchoring the lead 100 within tissue to resist
migration of the lead 100. In this embodiment, the anchoring
feature 118 comprises a plurality of serrations or notches 120 cut
into the film structure 107. The notches 120 may have any suitable
shape, dimension or spacing. Likewise, the notches 120 may be
symmetrical, non-symmetrical, present along one edge 111 of the
film structure 107 or along more than one edge. In this embodiment,
the anchoring feature 118 extends distally of the distal-most
electrode 106, however it may disposed at any location along the
lead 100.
[0069] FIG. 10 illustrates an example of a proximal end of the lead
100 corresponding to the distal end 102 of FIG. 9. Here, each of
the three traces 110 terminate in a contact pad 108. Each contact
pad 108 is then electrically connected with a connection terminal
(as will be described in a later section) which transmits
stimulation energy from the implanted IPG.
[0070] The thinness and flexibility of the dielectric film allow a
variety of different types of leads 100 to be formed. Such types
include layered leads, circular leads, leads which curl or wrap
around target tissue, leads which fold and expand, leads which
surround a target tissue, leads mounted on delivery devices and a
variety of other leads designs suitable for stimulating specific
types of target tissue, particularly a DRG.
[0071] FIGS. 11A-11B illustrate an embodiment of a layered lead
130. A layered lead 130 comprises two or more individual leads
which are layered and bonded together. FIG. 11A shows three
individual leads 100a, 100b, 100c, each comprising a film structure
107 having an electrode 106 disposed thereon and a trace 110. It
may be appreciated that each individual lead may alternatively have
a plurality of electrodes disposed thereon, such as in an array.
The three leads 100a, 100b, 100c are staggered so that the
electrodes 106 are exposed and facing the same direction. In this
embodiment, the traces 110 are positioned so that when the leads
are layered, the traces 110 are balanced across the layered lead
130. For example, the traces 110 may have opposing zig-zag or
serpentine shapes when layered. This improves flexibility and
handling characteristics of the lead 130. FIG. 11B provides a
side-view of the layered lead 130 of FIG. 11A. Such layering allows
each individual lead more surface area, such as for redundant
traces 110 for each electrode 106. Since the leads are so thin,
layering of the leads is still very thin and flexible. In addition,
insulation layers may be bonded between one or more of the
individual leads. In some embodiments, the proximal end of the
layered lead is layered in a mirrored fashion so that each of the
contact pads are exposed.
[0072] FIG. 12 illustrates an embodiment of a layered lead 130 in
an expanded view. The three leads 100a, 100b, 100c are staggered so
that the electrodes 106 are exposed and facing the same direction.
In this embodiment, the contact pads 108 are disposed on an
opposite side of each of the leads 100a, 100b, 100c. This provides
for the contact pads 108 to also be exposed and facing the same
direction when the leads are layered.
[0073] FIG. 13 illustrates an example of a lead, such as lead 100a,
which may be used in layering. The lead 100a comprises an elongate
film structure 107 having a distal end 102 and a proximal end 104.
FIG. 13A provides a detailed illustration of the distal end 102 of
the lead 100 of FIG. 13. As shown, the lead 100a includes at least
one electrode 106 plated on the "A-side" of the dielectric film
structure 107. In this embodiment, one electrode is present FIG.
13B provides a detailed illustration of the proximal end 104 of the
lead 100a of FIG. 13. The proximal end 104 includes a contact pad
108 on the "B-side" of the film structure 107 which is used to
connect with the IPG. In this embodiment, a circuit trace 110
extends from the electrode 106, along the "A-side" of the structure
107, through a via to the "B-side" of the structure 107 and
connects with the contact pad 108. Thus, when a plurality of such
leads are layered, as in FIG. 12, stimulation energy may be
transmitted from each of the staggered contact pads 108, through
the associated traces, to the associated staggered electrodes 106
to stimulate the desired target tissue.
[0074] FIG. 14 illustrates an example process and fixture for
forming a layered lead 130. Three individual leads 100a, 100b, 100c
are shown, each comprising a film structure 107 having an electrode
106 disposed thereon and a trace 110. In this embodiment, each lead
100a, 100b, 100c is of the same length, however differing sized
portions are shown for clarity. In addition, each lead 100a, 100b,
100c has an alignment hole 132. The alignment holes 132 are used to
assist in consistently and precisely aligning the leads in a
layered arrangement. A fixture 134 is shown having one or more
posts 136 positioned thereon. The posts 136 are sized and arranged
so that the posts 136 are passable through the alignment holes 132
when the leads 100a, 100b, 100c are placed thereon. Once the leads
100a, 100b, 100c are desirably positioned, the leads are bonded and
fixed in this arrangement. The layered lead 130 may then be removed
from the fixture 134. In some embodiments, the resulting alignment
holes 132 may be used for other purposes, such as for suturing a
portion of the layered lead 130 to tissue during implantation.
[0075] It may be appreciated that the flexible circuit leads 100
may have a variety of shapes, sizes and dimensions. In particular,
the distal end 102 may be shaped to provide a particular electrode
placement or to conform to a particular anatomy. For example, FIG.
15A illustrates a lead 100 of the present invention having an oval,
rounded or circular distal end 102. Here, the film structure 107 is
formed into the oval, rounded or circular shape and the electrodes
106 are arranged therearound, such as in a circular or arc pattern.
This arrangement may provide a particularly desirable stimulation
area or may more easily target a particular tissue, such as a
dorsal root ganglion DRG which may have a circular or oval shape.
FIG. 15B illustrates the lead 100 of FIG. 15A positioned so that
its distal end 102 is in proximity to a DRG. As shown, the distal
end 102 is positioned over the DRG so that its circular shape
substantially aligns with the circular shape of the DRG. The lead
100 is positioned so that the electrodes 106 face the DRG, and are
therefore represented in dashed line. Appropriate electrodes may
then be selected for stimulation of the DRG based on desired pain
relief. In some instances, the circular shape increases the number
of electrodes 106 able to be used for stimulation and promotes
selective stimulation of the DRG.
[0076] In addition, the film structure 107 may be curled or rolled
for ease of delivery and/or to wrap around a target tissue area.
FIG. 16A illustrates the distal end 102 rolled into a cylindrical
shape. Such a cylindrical shape may easily fit within a
cylindrically shaped delivery catheter or device. Thus, the lead
100 may be advanced from the delivery device in a rolled
orientation wherein it may be deployed to an at least partially
unrolled state. FIG. 16B illustrates the distal end 102 partially
unrolled and FIG. 16C illustrates the distal end 120 in an
unrolled, flat orientation. In an at least partially unrolled
state, the distal end 102 may fully or partially wrap around a
target tissue (such as the DRG or including the DRG). In this
configuration, the electrodes face each other having the target
tissue therebetween. Appropriate electrodes may then be selected
for stimulation of the tissue area therebetween based on patient
interview for best relief of pain. In some embodiments, one or more
obturators may be used to assist in unrolling and positioning of
the circular lead 100.
[0077] FIG. 17 illustrates a lead 100 of the present invention
having a pronged distal end 102. Here, the film structure 107 is
shaped to provide a plurality of elongate prongs 140, each prong
140 having an electrode 106 positioned thereon. The prongs 140 may
wrap around a delivery catheter or around a portion of the anatomy
during implantation. For example, FIG. 18 illustrates the lead 100
of FIG. 17 positioned so that its distal end 102 is in proximity to
a DRG. As shown, the distal end 102 is positioned over the DRG and
at least some of the prongs 140 wrap around the DRG. The lead 100
is positioned so that the electrodes 106 face the DRG, and are
therefore represented in dashed line. Appropriate electrodes may
then be selected for stimulation of the DRG based on desired pain
relief. In some instances, the pronged shape increases the number
of electrodes 106 able to be used for stimulation and promotes
selective stimulation of the DRG.
[0078] It may be appreciated that the film structure 107 is not
only bendable and flexible, but also foldable and creasable. Thus,
the leads 100 can form a variety of three-dimensional shapes which
assist in wrapping around particular tissues and anatomies. FIGS.
19-20 illustrate an embodiment of a shaped flexible circuit lead
500 of the present invention. The shaped lead 500 is comprised of
two individual leads 100a, 100b, each having at least one electrode
106 along one side of its distal end 102 and at least one
corresponding contact pad 108 along the opposite side of its
proximal end 104. Thus, the electrodes 106 and the contact pads 108
reside on opposite sides of each individual lead 100a, 100b. Lead
100a is folded to form a crease 502a along its length between the
electrodes 106 and the contact pads 108 so that an acute angle
.alpha. is formed between the back of the distal end (opposite the
electrodes 106) and the face of the proximal end 104 having the
contact pads 108 thereon. Likewise, lead 100b is folded to form a
crease 502b along its length between the electrodes 106 and the
contact pads 108 so that an acute angle .beta. is formed between
the back of the distal end (opposite the electrodes 106) and the
face of the proximal end 104 having the contact pads 108 thereon.
The angles .alpha., .beta. may be the same or different. The leads
100a, 100b are assembled so that the creases 502a, 502b are aligned
and the angles .alpha., .beta. face away from each other, as shown.
Consequently, the distal ends of the leads 100a, 100b form a V
shape wherein the electrodes 106 face each other within the mouth
of the V. The leads 100a, 100b may optionally be bonded together to
maintain this shaped lead 500. Alternatively, the leads 100a, 100b
may reside in this arrangement, allowing the leads to slide in
relation to each other to adjust position.
[0079] FIG. 20 illustrates the shaped lead 500 wrapped around a
target tissue area, including a target DRG. As shown, the lead 500
is positioned so the target tissue area resides between at least a
portion of the electrodes 106 along the mouth of the V. Thus,
stimulation energy E provided by the electrodes 106, is provided to
the tissue area laying therebetween (within the V). This provides a
higher likelihood of stimulating the target DRG, since the exact
location of the DRG within the target tissue area may not be
known.
[0080] Positioning of the contact pads 108 on opposite sides of the
assembled shaped lead 500 allows the joined proximal end 104 to
easily be connected to a connector (such as in a quick connect
arrangement) which is in turn connected with an IPG to supply the
stimulation energy E.
[0081] It may be appreciated that other shapes may be formed, such
as a "J" shape. Or, a triangular shaped lead may be formed having
three distal end portions (forming a tripod shape). When deployed,
this may covering a larger target tissue area than the V or J
shapes.
[0082] Likewise, the shapes may be formed by differing arrangements
of individual leads or portions of leads. For example, the above
described "V" shape may be formed by a longer flex circuit lead
which is creased and a smaller flex circuit bonded at the crease to
form the construct with an interconnect at the crease.
[0083] Delivery of the above described shaped lead 500 can be
accomplished by a variety of methods. For example, the lead 500 may
be delivered with the use of a delivery device such as illustrated
in FIGS. 21A-21B. In this embodiment, the delivery device 520
comprises a flattened tube 522 having a distal end 524 and a pair
of obturators 526a, 526b which are advanceable out of the distal
end 524. The obturators 526a, 526b are each comprised of a
preformed spring metal or memory metal which is able to curve or
bend to form an angle (such as angle .alpha. or angle .beta.) in
relation to the flattened tube 522.
[0084] FIG. 21A illustrates a first obturator 526a extending from
the distal end 524 of the tube 522. One of the individual flex
circuit leads 100a is attached to the obturator 526a, such as with
the use of a hook 528 which holds the lead 100a in place near the
distal tip of the obturator 526a during deployment. The obturator
526a bluntly dissects tissue as it is advanced, drawing the lead
100a into the dissected tissue. FIG. 21B illustrates a second
obturator 526b extending from the distal end 524 of the tube 522.
Another individual flex circuit lead 100b is attached to the
obturator 526b, such as with the use of a hook 528. This obturator
526b bluntly dissects tissue on the opposite side of the target so
that the target lies near or within the "V" of the obturators
526a,526b (and therefore between the electrodes 106 of the leads
100a, 100b)
[0085] Once deployed, the leads 100a, 100b are released from the
hooks 528 and the obturators 526a, 526b are retracted into the tube
522, leaving the leads 100a, 100b behind implanted in a "V" shaped
configuration. Appropriate electrode pairs may then be selected for
stimulation of the tissue area therebetween based on patient
interview for best relief of pain (in the case of DRG
stimulation).
[0086] The flexible circuit leads 100 of the present invention are
particularly suitable for implantation in areas of the human body
which benefit from highly thin and flexible leads. However, in some
portions of the anatomy, delivery of such thin and flexible leads
may be challenging due to tortuous or constrained delivery paths.
Therefore, the flexible circuit leads 100 may be attached to a
delivery device, such as a delivery catheter 140, as illustrated in
FIG. 22. The delivery catheter 140 comprises an elongate shaft 142
having a lumen 144 therethrough for passage of a stylet. Thus, the
catheter 140 may be comprised of a flexible polymer material to
retain the desirable flexibility of the lead 100 yet provide
sufficient rigidity for deliverability. In some embodiments, the
delivery catheter 140 remains in place with the flexible circuit
lead thereattached wherein both remain implanted. In such
embodiments, the flexible circuit lead 100 may wrap around the
catheter 140 so as to provide electrodes 106 on various surfaces of
the catheter 140. FIG. 23 illustrates a flexible circuit lead 100
particularly suited for wrapping around a catheter 140. Here, the
electrodes 106 are aligned in a lateral row so that the electrodes
106 will wrap around the circumference of the delivery catheter 140
when mounted thereon. It may be appreciated that any of the
flexible leads 100 described herein may be mounted on or attached
to a delivery device.
[0087] The leads of the present invention are typically passable
through a 16 gauge needle, 17 gauge needle, 18 gauge needle or a
smaller needle. In some embodiments, the electrode(s) of the
present invention have a less than 3 mm square area, preferably
less than 2 mm square area. In some embodiments, the electrodes
have an approximately 0.6-1 mm square area.
[0088] Such reduced dimensions in electrode area and overall size
(e.g. outer diameter) are possible due to the increased specificity
of the stimulation energy. By positioning at least one of the
electrodes on, near or about the desired target tissue, such as the
dorsal root ganglion, the stimulation energy is supplied directly
to the target anatomy (i.e. the DRG). Thus, a lower power may be
used than with a leads which is positioned at a greater distance
from the target anatomy. For example, the peak power output of the
leads of the present invention are typically in the range of
approximately 20 .mu.W-0.5 mW. Such reduction in power requirement
for the leads of the present invention may in turn eliminate the
need to recharge the power source in the implanted pulse generator
(IPG). Moreover, the proximity to the stimulation site also reduce
the total amount of energy required to produce an action potential,
thus decreasing the time-averaged power significantly and extending
battery life.
[0089] As described previously, the proximal end 104 of each lead
100 is joinable with an IPG to supply stimulation energy to the
electrodes 106. FIGS. 24-25 illustrate an example proximal end 104
joined with a connector 150 or portion of an IPG. As shown, the
proximal end 104 includes one or more contact pads 108 which are
electrically connectable to the connector 150 via one or more pins
152. As shown in cross-section in FIG. 24, the connector 150 is
able to make multiple connections with the flexible circuit lead
100. The contact pads 108 are placed over pins 152 that serve as
both a means of locating the flexible circuit lead 100 and making
the connection with the conductive material of the contact pads
108. Once the proximal end 104 of the lead 100 is placed over the
pins 152 a cover 154 is snapped into place, as shown in FIG. 25.
The act of snapping the cover 154 on the pins 152 makes the
electrical connection between the contact pads 108 and the IPG and
can connect many contact pads 108 with just one connection
action.
[0090] The connector cover 154 snaps in place with a predictable
and significant force, enough to maintain the connection. The pins
152 are spring loaded to maintain the correct connection force. The
springs may be comprised of a flexible polymer, such as
polyurethane or silicone, or a metal. The springs may be separate
or built into the pins 152 that make the connection via MEMS or
Wire EDM.
[0091] It may be appreciated that this connector 150 may be used
for any multiple lead connection that benefits from a simplified
means for connection. Such application may be for use with a
medical device or any electronics connections.
[0092] Although the foregoing Invention has been described in some
detail by way of illustration and example, for purposes of clarity
of understanding, it will be obvious that various alternatives,
modifications and equivalents may be used and the above description
should not be taken as limiting in scope of the invention.
* * * * *