U.S. patent application number 13/540468 was filed with the patent office on 2012-10-25 for surgically implantable electrodes.
Invention is credited to Giancarlo Barolat.
Application Number | 20120271391 13/540468 |
Document ID | / |
Family ID | 40534889 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120271391 |
Kind Code |
A1 |
Barolat; Giancarlo |
October 25, 2012 |
Surgically Implantable Electrodes
Abstract
The present inventions provide for paddle lead electrodes that
are capable of performing peripheral nerve stimulation, thereby
modulating, controlling and/or reducing neuropathic pain in a
patient, that are also surgically implantable, and that will remain
fixed in place at the site of implantation when in use. More
specifically, one or more embodiments of the electrodes of the
present inventions are capable of being surgically implanted
underneath a sheath of protective connective tissue that covers
electrically excitable tissues and are adapted to electrically
stimulate those tissues. Electrodes contemplated by embodiments of
the present inventions are particularly well suited for perineurial
implantation. Embodiments of the present inventions include methods
of use associated with the electrodes.
Inventors: |
Barolat; Giancarlo; (Golden,
CO) |
Family ID: |
40534889 |
Appl. No.: |
13/540468 |
Filed: |
July 2, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12252267 |
Oct 15, 2008 |
8214057 |
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13540468 |
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60980402 |
Oct 16, 2007 |
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Current U.S.
Class: |
607/116 |
Current CPC
Class: |
A61B 5/4824 20130101;
A61B 5/04001 20130101; A61N 1/0553 20130101 |
Class at
Publication: |
607/116 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Claims
1.-18. (canceled)
19. An electrode assembly for implantation in a patient,
comprising: a paddle body formed of a flexible elastomeric
material; the paddle body containing a forward portion and an
opposing rear portion, the forward portion connected to the rear
portion by said flexible elastomeric material, the forward portion
including a plurality of electrical contacts disposed within the
forward portion toward a ventral surface of the paddle body and the
rear portion devoid of electrical contacts, at least one contact
wire disposed within said flexible elastomeric material and
interconnected to at least one of the plurality of electrical
contacts, the contact wire extending along at least a portion of
the forward portion of the paddle; a lead connection located along
a dorsal surface of the forward portion of the paddle body, wherein
the lead connection directionally transitions the at least one
contact wire from a first orientation substantially planar to the
dorsal surface of the forward portion to a second orientation
substantially transverse the dorsal surface of the forward portion,
the at least one contact wire exiting the paddle body from the
dorsal surface of the forward portion.
20. The assembly of claim 19, wherein said paddle body includes a
groove formed between said forward portion and said rear portion,
said groove increasing the flexibility between the forward portion
and the rear portion.
21. The assembly of claim 19, wherein the forward portion includes
a distal end spaced from said lead connection, said distal end
tapered in thickness to facilitate surgical implantation.
22. The assembly of claim 19, wherein the forward portion has a
first length and the rear portion has a second length, the first
length being greater than the second length.
23. The assembly of claim 22, wherein the forward portion first
length is at least twice as large as the rear portion second
length.
24. The assembly of claim 19, wherein the paddle body has a
thickness less than 4 millimeters.
25. The assembly of claim 19, wherein the rear portion includes a
rear portion ventral surface and the paddle body defines an
insertion configuration with the rear portion ventral surface in
close proximity to the forward portion ventral surface, and an
anchoring configuration with the rear portion ventral surface and
the front portion ventral surface spaced from each other and facing
the same direction.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/252,267 filed on Oct. 15, 2008 which claims
the benefit of U.S. Provisional Patent Application No. 60/980,402
filed on Oct. 16, 2007, the entire content of which is incorporated
herein by reference in its entirety. The present application claims
the benefit of each of the foregoing applications.
FIELD
[0002] The present inventions are generally directed toward an
implantable means of modulating or controlling pain in a patient
experiencing chronic neuropathic pain or neuropathy. More
specifically, embodiments of the present inventions are directed
toward a novel, implantable electrode for use in a patient to
stimulate peripheral nerves and decrease chronic neuropathic pain,
or neuropathy, experienced by that patient, and methods of using
the same.
BACKGROUND
[0003] The perception of pain is a natural response to tissue
injury or trauma. In a normal patient, pain is perceived at the
time of injury and is resolved over time as the injury heals. In
contrast, neuropathic pain, or peripheral neuropathy, is a disease
of the peripheral nerves typified by a chronic or protracted state
of pain that continues long after a tissue injury has healed Like a
normal state of pain, peripheral neuropathy is typically caused by
acute tissue injury or trauma, however, in the case of neuropathic
pain, the nerve fibers themselves are damaged in addition to the
tissue, and this damage causes the nerve fibers to function
incorrectly. For example, acute damage or trauma to the nerves of
the peripheral or central nervous systems can cause individual
nerve fibers in those systems to misfire and produce spontaneous
signals they would not ordinarily produce (e.g. that are not in
response to any normal stimulus) and that the brain and spinal cord
do not normally receive. These spontaneous signals are abnormal
and, in the case of neuropathy, are perceived by the patient as
pain. Because these spontaneous signals typically continue long
after the tissue injury or trauma has healed, it is the nervous
system itself that is the cause of neuropathic pain, rather than
any tissue injury.
[0004] Neuropathic pain can be perceived as a steady burning, as a
"pins and needles" sensation, as an "electric shock," or as other,
similar sensations of pain. In some cases, peripheral neuropathy
can result in numbness and abnormal sensations such as dysesthesias
(impairment of sensations) and allodynias (exaggerated responses to
otherwise non-noxious stimuli), that occur either spontaneously or
in reaction to external stimuli. Therefore, neuropathic pain is
markedly different in perception and sensation from the ordinary,
acute pain that is induced by tissue trauma, such as stubbing a toe
or cutting a finger. This difference arises because ordinary pain,
or acute pain, which is caused by tissue injury or trauma, is
nociceptive in nature (e.g. is caused by a pain stimulus),
biologically self-limiting, and serves a protective biological
function by acting as a warning of ongoing tissue damage. In
contrast, neuropathic pain serves no biological protective function
at all; rather than being a symptom of trauma or disease, the pain
experienced by the patient is itself the disease. Neuropathic pain
is notoriously difficult to treat and tends to respond poorly to
standard pain treatments such as analgesics; in some cases even
strong opioid or narcotic analgesics such as morphine, codeine and
fentanyl, provide limited relief. Neuropathic pain has also been
known to worsen over time, rather than improve, making treatment
even more challenging for health care providers. Additionally, if
chronic neuropathic pain is inadequately treated, other symptoms
can develop as a result of the neuropathy apart from those
associated with the perception of pain, including chronic anxiety,
fear, depression, sleeplessness and impairment of social
interaction. In some patients, severe neuropathic pain has even led
to physical disability.
[0005] The mechanisms of action of neuropathic pain are typically
complex and can involve both peripheral and central nervous system
pathophysiology. The underlying dysfunction, or cause of the
neuropathic state of pain, may involve deafferentation (the
elimination or interruption of sensory nerve impulses) within the
peripheral nervous system (e.g. neuropathy), deafferentation within
the central nervous system (e.g. post-thalamic stroke) or an
imbalance between the two systems. An example of neuropathic pain
caused by the latter instance, an imbalance between the peripheral
and central nervous systems, is the disease state commonly known as
"phantom limb syndrome," where a patient has experienced an injury
or trauma that has resulted in the loss of a limb, or has had a
limb surgically removed. In this case the damage caused to the
nerves that originally served the missing limb causes those nerves
to malfunction or misfire as described above, which in turn causes
the patient's brain to perceive pain in a limb that is no longer
present.
[0006] Peripheral nerve stimulation ("PNS") was developed as a
method for managing chronic or protracted pain in the extremities
and has been used as a treatment for neuropathic pain since 1965.
PNS uses artificial means, such as electrical impulses, to
stimulate the nerves involved in the generation of neuropathic
pain, which can include both the nerves involved in the nociceptive
pain response and the nerves involved in non-pain, sensory
responses (e.g. touch) at the location of the neuropathy, and has
been found to reduce the symptoms of neuropathic pain perceived by
the patient, sometimes significantly. Several theories as to how
and why PNS causes relief from neuropathic pain in some individuals
exist, with the generally accepted theory being that, by
artificially stimulating the damaged or injured neurons or nerve
fibers that cause neuropathic pain, the damaged neurons become
desensitized and the pain signals that are sent by those neurons
become blocked or down-regulated. The artificial stimulation
employed in PNS can range greatly, from large artificial stimuli to
small stimuli, but will most typically be used in a range that
stimulates the neuropathic pain-causing neurons at a level that is
below their minimum threshold firing value. This is done by
applying an electrically stimulating signal to an individual nerve
or to a bundle of nerve fibers at a level that is above their
biological resting potential value, but that is not high enough to
trigger depolarization and neuronal firing, in an attempt to
decrease the firing sensitivity of those nerves, or to desensitize
them to all stimuli so that they transmit fewer signals. For
example, the use of PNS to artificially stimulate large, myelinated
touch and pressure responsive nerve fibers is theorized to prevent
the perception of neuropathic pain generated by those neurons by
interfering with their pain signal transmissions and causing those
nerve fibers to send non-painful "touch" signals to the brain in
their place. While this does not remove the abnormal sensation
altogether, it does serve to remove the pain.
[0007] PNS is typically performed by placing electrodes along the
course of the nerves that are generating neuropathic pain and then
using those electrodes to artificially stimulate the neuropathic
pain-causing nerves in order to attenuate or control the
transmission of pain signals generated. Several devices have been
created to perform this task that employ these types of electrodes
and they are an extremely safe, efficient, and effective way to
ameliorate a variety of severe neuropathic pain conditions. The
electrical current generated by the electrodes along the course of
the neuropathic nerves effectively tricks the brain into
attenuating the painful signals that are being spontaneously
generated by the damaged neurons, which causes relief from the
neuropathic pain. As a result, most patients are able to reduce or
discontinue pain medications after having received PNS. Once the
electrodes are put in place, they are used to administer a weak
electrical current to the nerve or nerves of interest. In practice,
this is typically performed as a two-step process. First, a
temporary or trial electrode is put in place along the neuropathic
pain-generating nerves and left for a brief period of time so that
the patient or health care provider can perform one or more test
runs to determine whether PNS will be effective for that patient.
The temporary electrode is connected to a power supply outside of
the patient that may be controlled by the patient or the health
care provider, as appropriate, while PNS is administered to that
patient on a trial basis. In the event that PNS is not helpful to
the patient, the temporary electrode is removed and the treatment
discontinued. If, however, it is found that PNS is providing the
patient with relief from neuropathic pain, the temporary electrode
is replaced with a permanent electrode that is connected to a power
source that is typically surgically implanted inside of the
patient, such as a battery pack similar to a pacemaker battery.
Once the permanent electrode is in place, the patient may resume
the activities of daily living.
[0008] Several types of electrodes have been developed for use in
performing PNS. Some perform PNS by passing an electric current,
and thus providing neurostimulation, through the skin. This form of
PNS is called transcutaneous electronic nerve stimulation ("TENS")
and is typically accomplished by placing small electrodes topically
along the path of the neuropathic pain-generating nerves, on the
skin of the patient. TENS therefore has the obvious benefits of
being noninvasive and readily adjustable in that the electrodes may
be moved, replaced, and relocated along the skin of the patient
quickly and easily. In spite of these benefits, however, many
patients that have been treated with TENS experience an inadequate
or minimal amount of pain relief or worse, experience no pain
relief at all. Additionally, even though the electrodes themselves
may be small in size and moved with relative ease, many of the
accompanying devices necessary to administer TENS to patients are
bulky, cumbersome, and non-portable, making TENS impractical for
use in ordinary life. Further, because the electrodes are placed
topically, the use of TENS precludes contact with water during
treatment, thereby preventing patients from enjoying many aspects
of normal, daily life without experiencing neuropathic pain.
[0009] Other treatment methods using PNS accomplish the desired
neurostimulation by surgically implanting electrodes directly to
and along the patient's spinal cord. This form of PNS is called
spinal cord stimulation ("SCS") and it typically uses a small lead
wire as the electrode, which is connected to a power source and
surgically implanted to the desired location along the spinal cord.
While this procedure has been shown to be medically efficacious in
some patients in the relief or reduction in the pain experienced by
peripheral neuropathy, it suffers from a unique disadvantage in
that several patients question the need to have a spinal procedure
performed in order to control limb pain and therefore opt not to
receive this form of treatment. An additional, more troubling
disadvantage to SCS is that the use of electrodes along the spine
and/or spinal nerves of a patient can result in broad electrical
coverage regardless of the amount of electrical current delivered,
which can result in several nerves being stimulated beyond those
causing the neuropathic pain. As may be appreciated, this may
induce abnormal sensations at bodily locations that are not damaged
or that are otherwise non-painful, because other spinal nerves
apart from those generating the neuropathic pain are being
stimulated. Because of this, it is often necessary for the health
care provider to decrease the amount of electrical current
delivered to the spine during SCS in order to minimize the
perception of abnormal sensations in non-affected areas. The
unfortunate effect of this is that the decreased electrical current
also limits the efficacy of SCS, causing the patient to experience
limited pain relief. A further disadvantage to SCS is the surgical
procedure that is required to accurately place the wire electrodes
along the spine. When performing this procedure, it is necessary
for the health care provider to accurately place the electrodes so
that they stimulate the nerves generating the neuropathic pain, but
they must also be properly anchored so that they remain in place
after implantation. The disadvantage arises because the techniques
traditionally used to anchor the wire electrodes used in SCS in
place are imprecise and the electrodes have a tendency to migrate
away from their point of surgical implantation in response to
minimal pulling forces, such as normal bodily movement, which can
lead to several problems with continued pain modulation and can
cause electrical stimulation in non-desired areas and of
non-desired tissues.
[0010] Nothing herein is to be construed as an admission that the
present invention is not entitled to antedate a patent, publication
or invention by another by virtue of prior invention.
SUMMARY
[0011] It would be advantageous to provide an electrode that is
capable of performing PNS, thereby modulating, controlling and/or
reducing neuropathic pain in a patient, that is also surgically
implantable, thereby allowing the patient to participate in normal
daily activities, and that will remain fixed in place at the site
of implantation while the patient moves normally. Various
embodiments of the present inventions address the shortcomings of
the known processes and devices. It is to be understood that the
present inventions include a variety of different versions or
embodiments, and this Summary is not meant to be limiting or
all-inclusive. This Summary provides some general descriptions of
some of the embodiments, but may also include some more specific
descriptions of certain embodiments.
[0012] The present inventions provide for paddle lead electrodes
that are capable of being surgically implanted underneath any of
the plurality of sheaths of protective connective tissues that
cover electrically excitable tissue in a patient, and that are
capable of directly stimulating those electrically excitable
tissues upon implantation. The present inventions also include
methods of using and methods of surgically implanting such
electrodes. Although well suited for use in human patients, and
although much of the discussion of the present inventions is
directed toward their use in humans, advantages offered by the
present inventions may be realized in the veterinary and scientific
fields for the benefit and study of all types of animals and
biological systems. Additionally, although the electrodes of the
present inventions are particularly well-suited for implantation
under the perineurium, and although much of the discussion of the
present inventions is directed toward their use in perineurial
applications, advantages offered by embodiments of the present
inventions may also be realized by implantation under other
protective connective tissues, including without limitation the
epineurium, the endoneurium, serous membranes, adventitia, the
pericardium, the perimysium, and similar protective connective
tissues.
[0013] In vertebrates, a major structure making up the central
nervous system is the spinal cord, which is encased within, and
protected by, the spine. The spinal nerves, as part of the
peripheral nervous system, serve to connect the central nervous
system to the body's sensory receptors, muscles, glands and other
components of the peripheral nervous system. Each spinal nerve
therefore has a first point of attachment to the spinal cord
itself, and at least one, and typically several, second points of
attachment to one or more target tissues. In humans, there are
thirty-one bilaterally-paired spinal nerves that run the length of
the vertebral backbone. Each spinal nerve is comprised of numerous
individual neurons, or nerve fibers, that are each individually
encased within a sheath of protective connective tissue called the
endoneurium, and each of which innervates a target tissue, thereby
performing a specific function. Within a single spinal nerve,
groups of these individual fibers are arranged into bundles called
fascicles, and each fascicle is encased by a sheath of protective
connective tissue called the perineurium. There are typically
several fascicles in a single spinal nerve, which are bundled
together, together with blood vessels and other supporting tissues,
and encased by a sheath of connective tissue called the epineurium
to form the spinal nerve. The perineurium is therefore one of the
supporting structures of the vertebrate peripheral nerve trunks,
consisting of layers of flattened cells and collagenous connective
tissue which surrounds a fascicle. The perineurium itself is not
electrically active and is thus incapable of conducting nerve
impulses; it functions as a protective layer for the neural tissues
it encases and forms a major barrier to diffusion within a spinal
nerve.
[0014] In accordance with at least one embodiment of at least one
of the present inventions, an implantable surgical electrode is
provided that comprises a forward portion located at a first end of
the electrode, a back portion located at a second end of the
electrode, a plurality of electrical contacts that are disposed
within the forward portion in a position that is substantially
toward a ventral side of the electrode, a plurality of contact
wires, and a lead or cable extending from a dorsal surface of the
electrode that is located between the forward portion and the back
portion. For one or more embodiments of one or more of the present
inventions, the contact wires are preferably fixed to the
electrical contacts at a first end and extend from the electrical
contacts through the forward portion, and at least partially into
the lead.
[0015] In accordance with one or more embodiments of one or more of
the present inventions, an implantable surgical electrode for
electrically stimulating tissues in a patient is provided. The
electrode comprises a forward portion located at a first end of the
electrode, a back portion located at a second end of the electrode,
a plurality of electrical contacts disposed at fixed locations
within the forward portion, a plurality of contact wires, equal in
number to the electrical contacts, disposed in fixed locations
within the forward portion, and a lead extending from a lead
connection located on a dorsal surface of the electrode between the
forward portion and the back portion. In at least one embodiment of
at least one invention, the contact wires are fixed to the
electrical contacts at a first end and extend from the electrical
contacts through the forward portion and through the lead
connection into the lead, and further extend through the lead to a
power source. In at least one embodiment of at least one invention
the electrode is about 4 cm in length, with the forward portion
comprising approximately three-quarters, or approximately 3 cm, of
that length, and the back portion comprising approximately
one-quarter, or approximately 1 cm, of the remaining length.
Additionally, the electrical contacts are disposed within the
forward portion in a position that is substantially toward a
ventral side of the electrode.
[0016] In accordance with still other aspects of the present
inventions, a method of surgically implanting an electrode in a
patient is presented. In at least one embodiment of at least one of
the present inventions, the method comprises first locating a first
tissue having a longitudinal axis that is capable of responding to
electrical stimulation and that is at least partially enclosed by
connective tissue, and creating an opening in the connective tissue
that is transverse to the longitudinal axis of the first tissue.
Then, once the opening is created, retracting at least a portion of
the connective tissue at the opening, providing an electrode having
a forward portion, a back portion and a lead located on a dorsal
surface of the electrode between the forward portion and the back
portion, and positioning the electrode over the opening. Once the
electrode is properly positioned, the method further comprises
inserting the forward portion of the electrode into the opening and
under the connective tissue in a first direction along the
longitudinal axis of the first tissue, and then inserting the back
portion into the opening and under the connective tissue in a
second direction along the longitudinal axis of the first tissue
while retaining at least a portion of the lead outside of the
opening. Once these tasks are completed, the method is concluded by
closing the opening on either side of the lead.
[0017] As used herein, "electrode" means a structure that includes
an electrical conductor that is used to make contact with and/or
electrically stimulate at least one tissue of a patient. U.S.
Patent Application Publication No. 2006/0136008 is incorporated
herein by reference. Though the description of the inventions
includes descriptions of one or more embodiments and certain
variations and modifications, other variations and modifications
are within the scope of the invention, e.g., as may be within the
skill and knowledge of those in the art, after understanding the
present disclosure. It is intended to obtain rights which include
alternative embodiments to the extent permitted, including
alternate, interchangeable and/or equivalent structures, functions,
ranges or steps to those claimed, whether or not such alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps are disclosed herein, and without intending to publicly
dedicate any patentable subject matter.
[0018] Various embodiments of the present inventions are set forth
in the attached figures and in the detailed description of the
inventions as provided herein and as embodied by the claims. It
should be understood, however, that this Summary does not contain
all of the aspects and embodiments of the present inventions, is
not meant to be limiting or restrictive in any manner, and that the
inventions as disclosed herein are and will be understood by those
of ordinary skill in the art to encompass obvious improvements and
modifications thereto.
[0019] Additional advantages of the present inventions will become
readily apparent from the following discussion, particularly when
taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a plan view of the dorsal side of an electrode in
accordance with at least one embodiment of at least one of the
present inventions;
[0021] FIG. 2 is a side elevation view of the electrode depicted in
FIG. 1;
[0022] FIG. 3 is a perspective view of the dorsal side of an
electrode in accordance with at least one embodiment of at least
one of the present inventions, the electrode bent in a curved
manner along its ventral side;
[0023] FIG. 4 is a perspective view of the dorsal side of an
electrode in accordance with at least some embodiments of at least
one of the present inventions, the electrode being placed inside of
a surgical incision;
[0024] FIG. 5A is a plan view of the dorsal side of an electrode in
accordance with at least one embodiment of at least one of the
present inventions;
[0025] FIG. 5B is a plan view of the dorsal side of the electrode
depicted in FIG. 5A, the electrode configured in an extended
position;
[0026] FIG. 6 is a side elevation view of the electrode depicted in
FIGS. 5A and 5B that has been surgically implanted along the
longitudinal axis of an electrically excitable tissue in a
patient;
[0027] FIG. 7A is a plan view of the dorsal side of an electrode in
accordance with at least one embodiment of at least one of the
present inventions;
[0028] FIG. 7B is a plan view of the dorsal side of the electrode
depicted in FIG. 7A, the electrode configured in an extended
position;
[0029] FIG. 8 is an enlarged plan view of the back portion of the
electrode depicted in FIGS. 7A and 7B;
[0030] FIG. 9 is a plan view of the dorsal side of an electrode in
accordance with at least one embodiment of at least one of the
present inventions;
[0031] FIG. 10 is a plan view of the dorsal side of the electrode
depicted in FIG. 9, the electrode configured in an extended
position;
[0032] FIG. 11 is a perspective view of a discrete bundle of
electrically excitable tissues encased in a sheath of protective
connective tissue that has had a transverse opening surgically cut
into it in accordance with at least one embodiment of at least one
of the present inventions;
[0033] FIG. 12 is a perspective view of the tissues and sheath of
connective tissue depicted in FIG. 11, with a portion of the
connective tissue retracted away from the transverse opening;
[0034] FIG. 13 is a perspective view of the tissues and sheath of
connective tissue depicted in FIGS. 11 and 12, with an electrode in
accordance with at least one embodiment of at least one of the
present inventions surgically implanted underneath the connective
tissue; and
[0035] FIG. 14 is a plan view of an electrode, lead and power
source in accordance with at least some embodiments of at least one
of the present inventions.
[0036] The drawings are not necessarily to scale and the drawings
may include exaggerated features for purposes of clarity.
DETAILED DESCRIPTION
[0037] Referring initially to FIGS. 1 and 2, an electrode 101 in
accordance with at least one embodiment of at least one of the
present inventions is provided. The electrode 101 preferably
includes a forward portion 104, a back portion 108, and at least
one, and more preferably, a plurality of electrical contacts 112
arranged in an array and disposed inside of the forward portion
104. The electrode thus comprises a forward portion 104 and back
portion 108 that combine to form a paddle. In addition, the
electrode 101 preferably further includes at least one, and more
preferably a plurality of contact wires 116, each having a first
end 120 connected to an electrical contact 112, and each of which
extend from the subject contact 112 internally along at least a
portion of the length of the forward portion 104 to a lead
connection 124 where a second end 128 of the contact wire 116 is
bundled together and electrically insulated from other contact
wires 116 into a lead 132 or cable that exits the electrode 101 at
a location preferably along the electrode's dorsal surface 136
situated between the forward portion 104 and the back portion 108
(see FIG. 2). In at least one embodiment of at least one of the
inventions, the contact wires 116 are present in a number equal to
the number of electrical contacts 112.
[0038] In at least one embodiment of at least one of the
inventions, the electrode 101 includes a score, groove or notch 140
on the ventral side 144 of the back portion 108 that preferably
spans the width of the electrode 101. The score, groove or notch
140 provides a means of increasing the flexibility of the electrode
101 during surgical implantation, as discussed in further detail
below.
[0039] In accordance with embodiments of the present inventions,
and as generally depicted in the figures, the electrode 101 is
substantially rectangular or paddle-like in shape, and the forward
portion 104 has smoothed or slightly rounded corners to facilitate
surgical implantation. The distal-most end of the forward portion
104 can be configured to any shape suitable for implantation, such
as a point, a half circle, and similar shapes, preferably providing
a configuration that is sufficiently flat or otherwise shaped so as
to not interfere with or damage the tissue encased within the
sheath of protective connective tissue, or the connective tissue,
upon implantation. In still other embodiments, the forward portion
104 may not only be shaped as described above, but may also taper
in thickness to reduce its profile and further facilitate surgical
implantation. In one or more embodiments, the shape of the forward
portion 104 of the electrode 101 is preferably configured so as to
not alter or interfere with the desired array of electrical
contacts 112 located inside of the forward portion 104.
[0040] The back portion 108 is located at a second end 152 of the
electrode 101, opposite from the forward portion 104, and as noted
above, in at least one embodiment of at least one of the present
inventions, the back portion 108 includes at least one notch 140 on
its ventral side 144 that extends to a depth of approximately
one-half of the thickness of the electrode 101. In at least one
embodiment of at least one of the present inventions, the back
portion 108 is substantially rectangular or paddle-like in shape
and the distal end of the back portion 108 preferably comprises a
shape suitable for implantation, such as that previously described
for the forward portion 104. In at least one embodiment, the back
portion 108 may be equal in length to, or longer than, the forward
portion 104 prior to implantation. Additionally, in one or more
embodiments, the back portion 108 may be cut or trimmed to its
final size and shape by the surgeon in advance of surgical
implantation to sufficiently conform the back portion 108 to the
anatomy of the patient. Accordingly, in at least one embodiment the
back portion 108 is made of a material that is sufficiently
workable so as to facilitate trimming and sizing prior to
implantation. In at least one embodiment of the present inventions,
the back portion 108 is made of the same material as the forward
portion 104 of the electrode 101. Further, in those embodiments of
the electrode 101 of the present inventions that include a notch
140, the back portion 108 may be optionally deformed or bent at the
notch 140 during implantation along its dorsal surface 136 (see
FIG. 4) or along its ventral surface 144 (see FIG. 3), to
facilitate implantation.
[0041] The electrical contacts 112 provide a means by which an
electrical current is passed from a power source 1401 (see FIG. 14)
through the lead 132, contact wires 116, and electrical contacts
112 to the patient's nervous tissue. It is therefore preferable
that the electrical contacts 112 be made of a material that
conducts and transmits a sufficient amount of electricity to
facilitate this purpose. Without wishing to be limited to any one
embodiment, the electrical contacts 112 can be made of any material
that is medically appropriate to conduct and transmit electricity
to a patient's tissues, including, without limitation, a material
containing copper, gold, silver, aluminum, platinum, iridium, or a
similarly conductive, hard, non-corrosive metal. Alternative
materials include conductive polymers and plastics, such as
polyacetylene. Tissue compatibility should be checked for all
materials implanted. In one aspect of the present inventions, the
electrical contacts 112 are sized so as to uniformly fit within the
forward portion 104 of the electrode 101, and that size may vary
depending upon the number of electrical contacts 112 present in the
forward portion 104, as well as with their arrangement. For
example, and without wishing to be limited to any embodiment, in
the case where the forward portion 104 contains one to seven
electrical contacts 112, the contacts 112 may be sized differently
than a different electrode 101 having a forward portion 104 with
eight or more electrical contacts 112. In the former case, the
electrical contacts 112 may be sized larger than the latter case in
order to deliver an effective amount of electrical current to the
patient's tissues with a fewer number of electrical contacts 112;
alternatively, the size of the electrical contacts 112 may not vary
so that the electrode 101 with fewer electrical contacts 112 can
deliver a smaller amount of current to the patient's tissues than
the electrode 101 with more electrical contacts 112. The number of
electrical contacts 112 in the forward portion 104 preferably
ranges from 1 to 12, more preferably from 4 to 10, and is even more
preferably 8. In at least one embodiment of at least one of the
present inventions, the electrical contacts 112 are situated within
the interior of the forward portion 104 such that they are closer
to the ventral surface 144 of the forward portion 104 than the
dorsal surface 136 (see FIG. 2). It is preferable that the ventral
surface 144 of the electrode 101 make contact with the target
tissue. Therefore, the location of the electrical contacts 112
close to the ventral surface 144 of the electrode 101 places them
in closer proximity to the tissue of interest, thus facilitating
the delivery of electrical current to that tissue.
[0042] The contact wires 116 provide the means by which electricity
is transmitted from a power source 1401 to the electrical contacts
112. In at least one embodiment of at least one of the present
inventions, the contact wires 116 each extend from an electrical
contact 112 inside of the forward portion 104 of the electrode 101,
through at least a portion of the length of the forward portion 104
to the lead connection 124, and through the lead 132 to a power
source. It is also preferable that the contact wires 116 are
bundled together and encased within the lead 132 when outside of
the electrode 101 (e.g. from the power source to the lead
connection 124) and are separated apart from each other inside the
forward portion 104 of the electrode 101 so that each individual
contact wire 116 may be connected to a single electrical contact
112 at its first end 120. In the present inventions, it is
contemplated that the contact wires 116 can be made of any material
that is medically appropriate to conduct and transmit electricity
from the external power source to the electrical contacts 112 and
that is sufficiently flexible so as to resist bending and breaking
as the lead 132 and the forward portion 104 bend and flex with the
patient's movements. Without wishing to be limited to any one
embodiment, it is presently anticipated that the contact wires 116
can be made of platinum, silver, iron, copper, aluminum, gold,
tungsten, or another similarly conductive, flexible, non-corrosive
metal, as well as conductive polymers and plastics.
[0043] The power source 1401 may be a hermetically sealed device
containing a power source for generating electrical currents and
the computer logic for the electrode 101. The power source 1401 may
be surgically implanted in the patient along with the electrode
101, or may optionally be located outside of the patient. The exact
configuration and location of the power source will be determined
by the surgeon at or prior to the time of implantation of the
electrode 101, and may vary from patient to patient. The power
source 1401 utilized may be selected from many power sources and/or
battery packs typically used to power surgically implantable
electrodes and devices, such as pacemaker battery packs, battery
packs for implantable cardioverter-defibrillators, or other
bio-operable power sources capable of generating sufficient
electrical current to stimulate the tissue of interest. An
implantable power source is typically spaced apart from the
electrode, though that is not required for purposes of the present
inventions.
[0044] The lead connection 124 is located at a point along the
dorsal side 136 of the electrode 101 between the forward portion
104 and the back portion 108 and provides the means by which the
contact wires 116 may exit the forward portion 104 and travel, via
the lead 132, to a power source 1401. It is therefore preferable
that the lead connection 124 and the lead 132 be configured so as
to be water-tight, thereby preventing the passage of fluids from
the patient or other sources outside of the electrode 101 into the
interior of the forward portion 104 and the lead 132, where they
may interfere with the ability of the contact wires 116 to properly
conduct electricity from the power source to the electrical
contacts 112. In at least one embodiment of at least one of the
present inventions, the lead 132 is an extension of the material
that encases the electrode 101, thereby creating a single sealed
environment around the interior of the lead 132 and the forward
portion 104 of the electrode 101. Having the lead connection 124
located along the dorsal surface 136 of the electrode 101 between
the forward portion 104 and the back portion 108 helps to keep the
electrode 101 in place at the surgical site as the patient moves.
This is in contrast to locating the lead 132 at other locations
along the electrode 101, such as caudally, at one end. When the
electrode 101 is implanted inside of a sheath of protective
connective tissue it is situated immediately superficial to the
electrically excitable tissue of interest. It is thus preferable
that the electrode 101 remain in place and not migrate from the
surgical site. As will be described in greater detail below, the
dorsally-located lead 132 between the forward portion 104 and the
back portion 108 helps to distribute external pulling forces
exerted on the electrode along the length of the electrode 101 and
thus along a line that is largely perpendicular to the direction of
pull, thereby helping to keep the electrode 101 in place as the
patient moves.
[0045] Referring now to FIGS. 3 and 4, an electrode 101 in
accordance with at least one embodiment of at least one of the
present inventions is presented in a side perspective view. In FIG.
3, the electrode 101 is shown bent in a crescent shape along its
ventral surface 144. In FIG. 4, the electrode is shown bent along
its dorsal surface 136, in an inverted V-shape, at the notch 140 as
it is being inserted into a surgical site, with a slight curvature
apparent in both the forward portion 104 and the back portion 108.
It is therefore preferable that the electrode 101 be made of a
material that is sufficiently flexible so as to allow the electrode
101 to bend and flex both as it is implanted into the patient's
body and thereafter in order to conform to the patient's unique
anatomy and to help keep the electrode 101 in place at the surgical
site as the patient moves. As can be appreciated, a sufficient
degree of flexibility will facilitate implantation of the electrode
101, as the electrode 101 will be capable of bending to a
substantial degree in order to conform to a surgical site. A
sufficient degree of flexibility can also serve to prevent
discomfort to the patient and damage to the patient's tissues after
the electrode 101 has been implanted, as the electrode 101 will be
capable of bending and flexing with the patient's body as the
patient undertakes normal daily activities. It is also preferable
that the electrode 101 be made of a material that repels water, or
that is completely water-tight, so as to prevent the patient's
bodily fluids and/or other liquids from entering the electrode 101
and interfering with the transmission of electrical currents to the
patient's target tissue. Additionally, it is preferable that the
electrode 101 be made of a material that is chemically and
electrically inert so as to prevent or impede the dissipation of
electrical current away from the contact wires 116 and/or
electrical contacts 112 when the electrode 101 is in use and also
to allow the electrical current to pass from the electrical
contacts 112 to the patient's nervous tissue unimpeded. In at least
one embodiment of at least one of the present inventions, the
electrode 101 is made of a medical grade, inert, elastomeric
polymer such as polytetrafloroethylene, or a silicone elastomer
such as Silastic.RTM. which is made by and available from The Dow
Chemical Company, or any other similar type of flexible material
that is suitable for surgical implantation and for purposes of the
electrodes 101 of the present inventions.
[0046] In FIG. 4, an electrode 101 according to at least some
aspects of at least one of the present inventions is shown being
placed into a surgical site in a patient. In order to accomplish
surgical implantation, an incision I is made in the protective
sheath of connective tissue surrounding the tissue of interest,
such as the perineurium, thereby exposing the electrically
excitable target tissue of interest underneath the connective
tissue. By using embodiments of the electrode 101 of the present
inventions, the surgical incision I can be quite small, only
slightly wider than the total width of the electrode 101 itself,
and still be sufficiently sized to allow for proper placement of
the electrode 101 along the tissue of interest, such as along the
line of the nerves that are associated with neuropathic pain in a
patient.
[0047] There are several ways in which the electrodes 101 of the
present inventions may be placed at a desired location in a
patient. In order to place the electrode 101 into the surgical
incision I in a manner similar to that depicted in FIG. 4, the
electrode 101 may be folded along its ventral surface 144 into an
inverted V shape and positioned over the incision I. In those
embodiments of the electrodes 101 that include a notch 140 in the
ventral surface 144 of the back portion 108, the notch 140 serves
to increase the flexibility of the electrode 101, thereby allowing
the electrode 101 to be bent at the notch to a greater degree than
it otherwise would have been able to in order to facilitate
placement into the incision I. By way of example, and without
wishing to be limited to any one embodiment, in order to accomplish
the surgical placement of the electrode 101 as depicted in FIG. 4,
the electrode 101 is bent along its ventral surface 144 at the
notch 140 such that it is folded almost completely in half, with
the ventral surface 144 of the forward portion 104 and the ventral
surface 144 of the back portion 108 brought into contact or very
close proximity with each other. Folding the electrode 101 at the
notch 140, which is located along the ventral surface 144 of the
back portion 108 in the depicted embodiment, results in the first
end 148 of the electrode being longer than the second end 152 in
the folded configuration. The first end 148 of the electrode 101 is
then fed into the incision I and moved underneath the protective
connective tissue in the desired direction along the patient's
tissue. To aid in proper placement of the first end 148 of the
electrode 101, the forward portion 104 of the electrode may be
curved or flexed along its dorsal surface 136 as it is fed into the
incision I. When the first end 148 of the electrode 101 has been
fed into the incision Ito the point where the second end 152 is at
the opening of the incision I, the second end 152 is fed into the
incision I in the opposite direction as the first end 148. It is
this point of insertion of the electrode 101 into the incision I
that is depicted in FIG. 4. Once both the first end 148 and the
second end 152 of the electrode 101 have been inserted into the
incision I, the electrode may be moved into the incision I such
that the first end 148 and second end 152 spread apart as shown,
just underneath the surface of the protective connective tissue.
When the electrode 101 is fully inserted into the incision I, the
lead 132 will be the only structure of the electrode 101 that
extends out of the incision I. Thereafter, the incision I may be
sutured closed around the lead 132, securing the electrode 101 in
place in the patient. The flexibility of the material of the
electrode 101 allows for this type of placement without any loss of
function in the electrode 101 and with little to no damage to the
underlying tissue.
[0048] As can be seen and appreciated from the embodiment depicted
in FIG. 4, the lead 132 and the back portion 108 prevent the
electrode 101 from moving or migrating in response to pulling
forces exerted on the electrode 101 by the patient's surrounding
tissues during normal movement. More specifically, in at least one
embodiment of at least one of the present inventions, the lead 132
is anchored to the electrode 101 at the lead connection 124, or at
a point along the dorsal surface 136 of the electrode 101 that is
between its first end 148 and its second end 152, rather than at
its caudal end. Because of this, a pulling force exerted on the
lead 132 will be distributed and dissipated along the longitudinal
plane of the electrode 101, over the forward portion 104 and the
back portion 108, in a direction that is largely perpendicular to
the direction of the pulling force. This perpendicular distribution
of force is in a direction that is away from the direction of the
pulling force, thereby preventing the pulling force from moving or
removing the electrode 101 from the surgical site. As the patient
moves, the surrounding tissues occurring naturally in his or her
body will have a tendency to exert pulling forces on the lead 132
from several different directions. As this happens, the electrode
101 of the present inventions resists movement from the surgical
site because the lead 132 pulls at a location toward the midline of
the electrode 101, rather than at one end. This results in the
pulling force being exerted toward the middle of the electrode 101,
which would result in movement of the electrode 101 but for the
presence of the forward portion 104 and the back portion 108, which
resist movement by their location underneath the sheath of
protective connective tissue surrounding the tissue of interest.
The distribution of a pulling force across the plane of the
electrode 101 in a direction that differs from the pulling force
helps the electrode 101 resist movement from the surgical site when
in use. This is in contrast to other electrodes that may be used
for a similar purpose, but that have the lead placed caudally, or
at one end of the electrode, as a pulling force exerted along the
lead of these electrodes also pulls directly on a terminal end of
the electrode. The direction of the pulling force is thus in the
same plane as the full length of the electrode, which increases the
risk that the direction of pull will cause the electrode to migrate
away from the surgical site, or be removed from the site entirely,
when in use. The presence of the back portion 108 at the second end
152 of the electrodes 101 of the present inventions thus provides
the added length to the electrodes 101 that helps deflect pulling
forces across the length of the electrode 101 in a direction that
is perpendicular to the original force. The electrodes 101 of the
present inventions are thus able to resist migration and movement
away from the surgical site as the patient moves because of the
presence of the back portion 108.
[0049] Referring now to FIGS. 5A, 5B and 6, an electrode 501
according to at least one embodiment of at least one of the present
inventions is presented. In the depicted embodiment, the back
portion 504 is not included as an integral, planar extension of the
forward portion 104, but rather as a telescoping portion that is
slid out from around the forward portion 104 after the electrode
501 has been placed in the surgical site. Therefore, the back
portion 504 is kept out of the way during insertion of the
electrode 501 into the surgical site, and is thereafter extended
out from under the forward portion 104 during or after implantation
of the forward portion 104, to anchor the electrode 501 in place.
In this embodiment, the back portion 504 is a separate sleeve that
fits snugly around all or a portion of the forward portion 104 that
is configured to slide along the length of the forward portion 104
in one of two directions: away from the first end 148 of the
electrode 501 when being extended out to its final, implanted
configuration (see FIG. 5B), or toward the first end 148 as it is
being retracted. As shown in FIG. 5A, when the back portion 504 is
retracted over a portion of the forward portion 104, the length of
the electrode 501 is reduced by the length of the back portion 504.
This reduction in length facilitates surgical implantation by
allowing the electrode 501 to be implanted by sliding it into an
incision in a single direction. Although optional, in this
embodiment there is less of a need to fold the electrode 501 prior
to insertion and thereafter spread the two halves of the electrode
501 once insertion has been achieved, as previously described
because the back portion 504 may be fully retracted over a portion
of the forward portion 104 during implantation. Preferably, the
back portion 504 does not completely encircle or enclose the
forward portion 104 of the electrode 501, but is rather shorter in
length than the forward portion 104, and comprises a planar portion
that spans the width of the electrode's 501 ventral side 144 with
two arm portions 508 that extend over the sides of the electrode
501 and at least partially onto its dorsal surface 136 as depicted.
As shown in FIG. 5A, when retracted the back portion 504 does not
cover any of the electrical contacts 112 contained in the forward
portion 104 so as to allow for the intended use of the electrode
501 when the back portion 504 is fully retracted. As can be
appreciated, should the back portion 504 cover all or any portion
of an electrical contact 112 during use, it may impede or prevent
the transmission of electrical impulses from the electrode 501 to
the target tissue. By configuring the back portion 504 so that it
does not cover any of the electrical contacts 112 even when fully
retracted, the electrode 501 may be placed in a patient and put to
use without extension of the back portion 504, if so desired, and
the surgeon can be assured that the back portion 504 will not
interfere with the intended use of the electrode 501. The foregoing
notwithstanding, in some embodiments the back portion 504 may be
configured to cover some or all of the electrical contacts 112
prior to extension, so as to provide a longer stabilizing portion
upon extension. In these embodiments, the back portion 504 may be
trimmed to conform to the unique aspects of the patient's anatomy
prior to insertion and, in any event, is extended such that it does
not cover any electrical contacts 112 during use of the electrode.
Furthermore or in the alternative, apertures (not shown) within the
back portion 504 can be provided to permit the electrical current
to reach the targeted tissue when the back portion 504 is fully
retracted.
[0050] As can be seen in FIGS. 5A and 6, in at least one embodiment
of at least one of the present inventions, the arm portions 508
extend only a short distance across the dorsal surface 136 of the
electrode 501. This short distance is still sufficient to hold the
back portion 504 to the dorsal surface 144 of the electrode 501
prior to extension and to hold the back portion 504 in place after
the electrode 501 has been surgically implanted and the back
portion 504 has been at least partially extended. In other
embodiments, the arm portions 508 of the back portion 504 extend
farther across the dorsal surface 136 of the electrode 501 to any
point up to the lead connection 124, thus making the back portion
504 more sleeve-like in appearance. In those embodiments where the
arm portions 508 of the back portion 504 extend farther across the
dorsal surface 136 of the electrode 501, the back portion 504 has
more structure and thus provides for a stronger stabilizing portion
of the electrode 501 when extended. In order for the back portion
504 to provide the necessary rigidity to enable it to deflect
pulling forces as previously described, in some embodiments the
back portion 504 is made of a material that is more rigid than the
flexible material of the forward portion 104 of the electrode 501.
The use of more rigid material ensures that the back portion 504
will have the structural integrity necessary to remain in place
upon extension and to deflect pulling forces as intended. While not
wishing to be limited to any one embodiment, the rigid material may
include, without limitation, surgical grade plastics, silicone, or
rubber.
[0051] As shown in FIG. 5B, as the electrode 501 is placed into the
surgical site, the back portion 504 is extended away from the
forward portion 104 along the longitudinal axis L-L of the
electrode 501, bringing the electrode 501 to its full length. This
extension may take place by any number of means and by the use of
any number of surgical instruments. In at least one embodiment of
at least one of the present inventions, the extension may take
place by the surgeon using a surgical instrument, such as forceps,
wire, a probe, or similar device, to push the arm portions 508 of
the back portion 504 away from the forward portion 104 until the
back portion 504 is in the desired position. In this embodiment,
the back portion 504 may be used to customize the size and length
of the electrode 501 both outside of the patient and after
placement within the patient. Outside of the patient, the back
portion 504 may be trimmed as described above to approximate the
size of the surgical site and thus facilitate placement. Once
inside the patient, the back portion 504 may be completely extended
or extended to a length suitable for the patient's anatomy,
depending upon the size and configuration of the surgical site, to
further customize the size of the electrode 501. Preferably, when
extended to the proper configuration within a patient, the back
portion 504 does not cover any portion of the ventral surface 144
of the electrode 501 housing the electrical contacts 112, so as to
not prevent the transmission of electricity from an outside source
to the patient's tissues.
[0052] As can be seen in FIG. 6, the profile of the electrode 501
is not significantly increased with the inclusion of the back
portion 504, which is configured to be sufficiently small so as to
not increase the thickness of the electrode 501 beyond the
anatomical limits of the patient. This facilitates placing the
electrode 501 into confined areas, such as underneath the
perineurium, as a device that is too thick may cause damage to the
patient's tissues during implantation, as well as during normal
use. In FIG. 6, the electrode is shown in a side elevation view
inside of a surgical site with the back portion 504 not yet
extended from the forward portion 104.
[0053] Referring now to FIGS. 7A, 7B and 8, an electrode 701
according to at least one embodiment of at least one of the present
inventions is presented. In the depicted embodiment, the back
portion 704 is not a sleeve-like structure that is slid along the
outside of the electrode, but is rather a tab that is extended from
the forward portion 104 of the electrode 701 to bring the electrode
701 to full length. In the depicted embodiment, as best seen in
FIG. 8, the forward portion 104 of the electrode 701 includes a
separate pocket 708 that houses the back portion 704. It is
preferable that the pocket 708 be located in the forward portion
104 toward its dorsal surface 136 so as to not create any
structures that will interfere with the transfer of electrical
impulses from the electrode 701 to the patient. By placing the
pocket 708 along the dorsal surface 136, the positioning of the
electrical contacts 112 close to the target tissue is
maintained.
[0054] In the embodiment depicted in FIGS. 7A, 7B and 8, the back
portion 704 includes an aperture 712 in the end opposite to the
forward portion 104 that may be used to facilitate the extension of
the back portion 704 by providing a structure where a surgical
instrument may be used to extend the back portion 704. The back
portion 704 may optionally include a structural feature that houses
the aperture 712, such as a half moon shaped protrusion or similar
feature, as shown in FIGS. 7A and 7B. In order to utilize the
aperture 712 to extend the back portion 704, a surgical instrument,
such as a wire probe or similar instrument with a tip fine enough
to fit totally or partially within the aperture 712, may be used to
extend the back portion 704 after the electrode 701 has been
inserted into the patient, or during insertion. As shown in FIG.
7B, the back portion 704 includes a groove 716 that approximates
the width of the lead connection 124. The groove 716 ensures that
the back portion 704, when not extended, does not interfere with
the contact wires 116 as they are bundled together to move into the
lead 132 at the lead connection 124. The groove 716 therefore
allows the back portion 704 to extend from the forward portion 104
of the electrode by sliding past the lead connection 124 on both
sides. In order for the back portion 704 to provide the necessary
rigidity to enable it to deflect pulling forces as previously
described, in at least one embodiment of at least one of the
present inventions, the back portion 704 is made of a material that
is more rigid than the flexible material of the forward portion 104
of the electrode 701. The use of more rigid material ensures that
the back portion 704 will have the structural integrity necessary
to remain in place upon extension and deflect pulling forces as
intended. While not wishing to be limited to any one embodiment,
the rigid material may include, without limitation, surgical grade
plastics, silicone, or rubber.
[0055] Referring now to FIG. 8, an embodiment of the pocket 708 of
the forward portion 104 and the back portion 704 is depicted in
accordance with at least one embodiment of at least one of the
present inventions. In the depicted embodiment, the back portion
704 is held in an extended configuration by a pair of projections
801 that prevent the back portion 704 from backward movement within
the pocket 708 by engaging with teeth 804 located along the
interior walls 808 of the pocket 708. As the back portion 704 is
extended, the projections 801 are moved past the teeth 804 by
cooperatively shaped angled surfaces on the projections 801 and
teeth 804. The projections 801 are located along a pair of
projection arms 812 that are biased to engage the interior walls
808 of the pocket 708. The angled surfaces allow the back portion
704 to move past a single pair of teeth 804 by a slight deflection
of the projection arms 812 of the back portion 704. As the
projection arms 812 deflect, they move toward each other inside of
the pocket 708 in the forward portion 104. Once past the angled
face of each tooth 804, the projection arms 812 snap back into
their original, undeflected configuration, where the flat surfaces
of the teeth 804 are then cooperatively engaged by corresponding
flat surfaces of the projections 801, which prevents backward
movement of the back portion 704.
[0056] Referring now to FIGS. 9 and 10, an electrode 901 according
to at least one embodiment of at least one of the present
inventions is shown. In the depicted embodiment, as with the
previous embodiment, the back portion 904 is not a sleeve-like
structure that is slid along the outside of the electrode 901, but
is rather a tab that is extended from the forward portion 104 of
the electrode 901 to bring the electrode 901 to full length. The
forward portion 104 of the electrode 901 thus similarly includes a
separate pocket that houses the back portion 904. It is also
preferable that the pocket be located in the forward portion 104
toward its dorsal surface 136 so as to not create any structures
that will interfere with the transfer of electrical impulses from
the electrode 901 to the patient. It is also intended that this
embodiment utilize a way of preventing backward movement, such as
that depicted in FIG. 8. Unlike the prior embodiment, however, in
this embodiment the back portion 904 is prevented from extending
beyond a specified distance by a tether 908 that has one end
attached to the forward portion 104 of the electrode 901 and the
other end attached to the aperture 712 of the back portion 904. The
presence of the tether 908 ensures that the surgeon will not
inadvertently remove the back portion 904 from the electrode 901
entirely during extension. Additionally, the tether 908 may be
sized to conform to the unique aspects of a patient's anatomy and
thus prevent the back portion 904 from being extended to a length
that would be harmful to the patient.
[0057] As with the previous embodiment, in order for the back
portion 904 to provide the necessary rigidity to enable it to
deflect pulling forces as previously described, in at least one
embodiment of at least one of the present inventions, the back
portion 904 is made of a material that is more rigid than the
flexible material of the forward portion 104 of the electrode 901.
The use of more rigid material ensures that the back portion 904
will have the structural integrity necessary to remain in place
upon extension and deflect pulling forces as intended. While not
wishing to be limited to any one embodiment, the rigid material may
include, without limitation, surgical grade plastics, silicone, or
rubber.
[0058] For the various embodiments of the electrodes 101, 501, 701,
901 described herein, preferably, the width of the electrodes
ranges from approximately 5 to 12 millimeters, more preferably from
8 to 12 millimeters, and more preferably yet, is about 12
millimeters wide. The thickness of the electrodes preferably ranges
from approximately 2 to 4 millimeters, and more preferably, is
about 3 millimeters thick. The length of the electrodes preferably
ranges from about 2 to 6.5 centimeters, more preferably about 3 to
5 centimeters, and more preferably yet, about 4 centimeters long.
It is also preferable that the forward portion 104 take up
approximately three-quarters, or about 75%, of the length of the
electrodes, and the various embodiments of the back portions 108,
504, 704, 904 comprise the balance of the length of the electrodes.
As can be seen from the embodiment depicted in FIG. 2, the
electrodes are preferably relatively thin in profile, being
substantially wider and longer than they are thick. This relatively
thin profile facilitates surgical implantation, particularly when
the electrodes are placed within a sheath of protective connective
tissue covering a tissue of interest. As can be appreciated, this
thin profile helps ensure that the electrodes will not damage the
tissue of interest during surgical implantation, and also helps
ensure that the electrodes do not damage the connective tissue
after they have been implanted, such as when the patient moves
during normal activity.
[0059] In accordance with embodiments of the present inventions,
the electrical contacts 112 and contact wires 116 are disposed
inside of the forward portion 104 of the electrodes, and are
completely encased within the material encasing the electrodes. It
is also preferable that the electrical contacts 112 and the contact
wires 116 be placed within the forward portion 104 in permanently
fixed locations, so as to prevent movement or migration during use.
This may be accomplished by any one of several ways and may
include, without limitation, setting the contact wires 116 and
electrical contacts 112 in their desired locations inside a mold
and then pouring or injecting a liquid or molten material over them
so as to completely encase them within the forward portion 104 of
the electrode. As can be appreciated, by encasing the electrical
contacts 112 and the contact wires 116 within the material of the
forward portion 104 of the electrodes, the material itself can
serve as a water-tight, protective barrier for the electrical
contacts 112 and the contact wires 116. A water-tight barrier helps
ensure that the electrodes will function properly after they have
been implanted into one or more patients, and will not experience
any electrical interference from outside liquids and/or a patient's
bodily fluids, which are typically water-based and therefore
capable of conducting and dissipating, the electrical stimulation
delivered to the patient by the electrodes.
[0060] The electrical contacts 112 may be arranged in patterns
inside of the forward portion 104, with each pattern designed to
deliver electrical stimulation to a patient under appropriate
physiological conditions. While not wishing to be limited to any
particular embodiment, the electrical contacts 112 may be arranged
in patterns that include, without limitation, a single electrical
contact 112 placed within the forward portion 104, a plurality of
electrical contacts 112 arranged in a single line inside of the
forward portion 104, a plurality of electrical contacts 112
unevenly spaced within the forward portion 104, a plurality of
evenly paired electrical contacts 112 arranged in two substantially
parallel lines running the length of the forward portion 104, or a
plurality of electrical contacts 112 arranged in a staggered
pattern along two parallel lines running the length of the forward
portion 104 (see FIG. 1), among others. In some embodiments, the
contact wires 116 are placed within the interior of the forward
portion 104 so that each connects to a single electrical contact
112 at a first end 120 and then runs at least a portion of the
length of the forward portion 104 to the lead connection 124. In
those embodiments with two substantially parallel lines of
electrical contacts 112, the contact wires 116 are generally
centrally disposed in the forward portion 104, and run between the
parallel lines generally along the midline of the forward portion
104. It is also an aspect of at least one of the present inventions
for the electrical contacts 112 to be configured in any shape that
is suitable for the delivery of an electrical current to the tissue
of interest. Without wishing to be limited to any one embodiment,
and without limitation, the electrical contacts 112 can be shaped
as squares, rectangles, circles, or any other shape that will
effectively deliver current to the tissue of interest.
[0061] In one or more embodiments of one or more of the present
inventions, an insulating material is placed inside of the forward
portion 104 at a location that is generally between the electrical
contacts 112 and the contact wires 116. In this regard, each
contact wire 116 passes through the insulating material immediately
after its point of attachment to its respective electrical contact
112, and then runs the length of the forward portion 104 toward the
lead connection 124 on the opposite side of the insulating material
from the electrical contacts 112. In this embodiment, the
insulating material is sufficiently flexible so as to not bend or
break during normal use of the electrodes and serves as a barrier
to the transmission of electricity from the contact wires 116 to
the patient's nervous tissue, thereby increasing the accuracy of
the placement of the electrical stimulation along the patient's
tissues.
[0062] All of the dimensions provided herein are for exemplary
purposes and are not intended to be limiting. Other dimensions are
possible, and such other dimensions are within the scope of the
present invention.
[0063] Referring now to FIGS. 11, 12, and 13, a method of
implanting any one of the various embodiments of the electrodes
101, 501, 701, 901 described herein underneath a sheath of
protective connective tissue, and thus in contact with an
electrically excitable tissue of a patient, according to at least
some aspects of at least one of the present inventions is
presented. According to the method, a tissue 1101 that is capable
of receiving and responding to electrical stimulation and that has
a sheath of protective connective tissue 1104, is first surgically
located and exposed. In at least one embodiment of at least one of
the present inventions, the tissue 1101 is a nerve or group of
nerves and the sheath of protective connective tissue 1104 is the
perineurium. As seen in FIG. 11, once the tissue 1101 is located, a
small, transverse opening 1108 is made in the protective connective
tissue 1104, in order to expose the tissue 1101 underneath. The
opening 1108 need only be slightly wider than the width of the
electrode in order to allow for proper placement of the electrode
along the tissue 1101 of interest. In that regard, the method of
placing an electrode according to at least one embodiment of at
least one of the present inventions only requires a limited
exposure of the underlying tissue 1101 in order to place the
electrode, since the surgeon only needs to make a small, transverse
opening along the protective connective tissue 1104. Thereafter,
the protective connective tissue 1104 may be optionally retracted
in order to facilitate insertion of the electrode (FIG. 12).
[0064] Given that the dimensions of the electrodes of the present
inventions are quite small, in that the width of the electrodes
preferably ranges from approximately 2 to 4 millimeters thick, the
amount of retraction required in advance of insertion is minimal
and retraction may not be required in all patients. A decrease in
the amount of manipulation of the connective tissue 1104 when
performing the methods of the present inventions minimizes the risk
of damage to the patient. Once the connective tissue 1104 is
sufficiently retracted, the forward portion 104 of the electrode is
inserted under the connective tissue 1104 along the long axis of
the underlying tissue 1101, which is preferably a nerve. Placing
the electrode under the connective tissue 1104 assures that the
electrode will be in direct contact with the tissue 48. It is
preferable that the electrode is located underneath the connective
tissue 1104 in such a way so as to run parallel with the
longitudinal axis of the target tissue 1101.
[0065] In at least one embodiment of at least one of the present
inventions, the forward portion 104 of the electrode is inserted,
preferably along the longitudinal axis of the electrically
excitable tissue 1101. The forward portion 104 is preferably
inserted such that the electrode will provide electrical
stimulation to the target tissue 1101 of interest. The back portion
108, 504, 704, 904 is then inserted under the connective tissue
1104 in the opposite direction of the insertion of the forward
portion 104. As best seen in FIG. 13, once the forward portion 104
and the back portion have been placed as described, the lead
connection 124 will be oriented in the surgical site at the small
transverse opening 1108 such that the lead 132 is typically the
only portion of the electrode that remains outside of the opening
1108. The small transverse opening 1108 in the connective tissue
1104, is then closed around the lead 132, such as by the use of
fine sutures placed on either side of the lead 132. This
essentially locks the electrode into position, since the lead 132
prevents it from sliding along its longitudinal axis, and the
adhesion of the connective tissue 1104 to the underlying tissue
1101 in areas adjacent to the opening 1108 will keep the electrode
from moving from side to side.
[0066] Under some circumstances, it may be necessary for the
surgeon to reposition the electrode after it has been placed in the
patient. In the event that the surgeon determines that the
electrode needs to be moved laterally, or sideways along the short
axis of the tissue 1101, the transverse opening 1108 need only be
elongated in the desired direction. The connective tissue 1104 is
then retracted away from the underlying tissue 1101 as previously
stated, and the electrode moved. Once the electrode is set in the
new position, the opening 1108 is closed around the lead 132 as
previously described, thus locking the electrode in place at the
new location. In the event that the electrode needs to be
repositioned in a longitudinal direction along the length of the
target tissue 1101, the connective tissue 1104 can be divided
longitudinally, or along the long axis of the tissue 1101, in the
desired direction of repositioning. As with repositioning in a
transverse direction, the connective tissue 1104 is then retracted
and the electrode moved. After repositioning is complete, the
additional longitudinal incision is closed around the lead 132 in
order to secure the electrode in place.
[0067] Embodiments of the present invention may comprise any one or
more of the novel features described herein, including in the
Detailed Description, and/or shown in the drawings. The claims may
include one or more features of any one or more of the embodiments
described herein. For example, one or more features of one
embodiment may be claimed in combination with one or more features
of another embodiment, and no portion of this specification limits
such claims.
[0068] The present inventions, in various embodiments, include
components, methods, processes, systems and/or apparatuses
substantially as depicted and described herein, including various
embodiments, subcombinations, and subsets thereof. Those of skill
in the art will understand how to make and use the present
inventions after understanding the present disclosure. The present
inventions, in various embodiments, include providing devices and
processes in the absence of items not depicted and/or described
herein or in various embodiments hereof, including in the absence
of such items as may have been used in previous devices or
processes, e.g., for improving performance, achieving ease and\or
reducing cost of implementation.
[0069] The foregoing discussion of the inventions has been
presented for purposes of illustration and description. The
foregoing is not intended to limit the inventions to the form or
forms disclosed herein. In the foregoing Detailed Description for
example, various features of the inventions are grouped together in
one or more embodiments for the purpose of streamlining the
disclosure. This method of disclosure is not to be interpreted as
reflecting an intention that the claimed inventions require more
features than are expressly recited in each claim. Rather, as the
following claims reflect, inventive aspects lie in less than all
features of a single foregoing disclosed embodiment. Thus, the
following claims are hereby incorporated into this Detailed
Description, with each claim standing on its own as a separate
preferred embodiment of the inventions.
[0070] Moreover though the description of the inventions has
included descriptions of one or more embodiments and certain
variations and modifications, other variations and modifications
are within the scope of the inventions, e.g., as may be within the
skill and knowledge of those in the art, after understanding the
present disclosure. It is intended to obtain rights which include
alternative embodiments to the extent permitted, including
alternate, interchangeable and/or equivalent structures, functions,
ranges or steps to those claimed, whether or not such alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps are disclosed herein, and without intending to publicly
dedicate any patentable subject matter.
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