U.S. patent application number 17/163840 was filed with the patent office on 2021-05-27 for system, devices, and methods combining spinal stabilization and neuromodulation.
The applicant listed for this patent is SynerFuse, Inc.. Invention is credited to Gregory F. Molnar, Nazmi Peyman, Harry Puryear, Justin D. Zenanko.
Application Number | 20210154469 17/163840 |
Document ID | / |
Family ID | 1000005381861 |
Filed Date | 2021-05-27 |
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United States Patent
Application |
20210154469 |
Kind Code |
A1 |
Molnar; Gregory F. ; et
al. |
May 27, 2021 |
SYSTEM, DEVICES, AND METHODS COMBINING SPINAL STABILIZATION AND
NEUROMODULATION
Abstract
A pain management system includes a spinal stabilization device
and a neuromodulation device. The spinal stabilization device
includes a rod, a plurality of pedicle screws each having a
screw-head defining a screw-head cavity configured to receive a
portion of the rod, and a corresponding plurality of inserts
configured to engage with the inner wall of the cavity to secure
the rod in place in the cavity. The neuromodulation device includes
a therapy module comprising electronics packaged within a housing.
The housing has a form factor having at least one feature
configured to mate with a corresponding feature of the screw-head
of one of the plurality of pedicle screws. The respective features
mate in a manner that enables the therapy module to mechanically
couple to and subsequently decouple from the screw-head of the
pedicle screw.
Inventors: |
Molnar; Gregory F.; (Blaine,
MN) ; Puryear; Harry; (Shoreview, MN) ;
Peyman; Nazmi; (Glen Allen, VA) ; Zenanko; Justin
D.; (Minnetrista, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SynerFuse, Inc. |
Minneapolis |
MN |
US |
|
|
Family ID: |
1000005381861 |
Appl. No.: |
17/163840 |
Filed: |
February 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16409616 |
May 10, 2019 |
10933234 |
|
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17163840 |
|
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62670034 |
May 11, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/7034 20130101;
A61N 1/0558 20130101; A61N 1/0553 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05; A61B 17/70 20060101 A61B017/70 |
Claims
1. An implantable medical lead comprising: a ribbon structure
having a first side and a second side opposite the first side; a
plurality of first electrodes associated with the first side and
arranged in a first pattern; and a plurality of second electrodes
associated with the second side and arranged in a second pattern;
wherein the ribbon structure is configured to transition from a
planar state to a non-planar state upon the application of a force
and to remain in the non-planar state upon removal of the
force.
2. The lead of claim 1, wherein the non-planar state corresponds to
an undulating state during which the ribbon structure bends in at
least one, or in a series of successive curves in alternating
directions, along a longitudinal axis extending down the center of
the ribbon structure.
3. The lead of claim 2, wherein the undulating state comprises at
least one curve having a radius of curvature in the range of 1 mm
and 3 mm.
4. The lead of claim 1, wherein the non-planar state corresponds to
a twisted state during which the edges of the ribbon structure
along the length of the ribbon structure curve about a longitudinal
axis extending down the center of the ribbon structure.
5. The lead of claim 1, wherein the first pattern is a
two-dimensional array and the plurality of first electrodes are
separated by electrically insulative material associated with the
first side of the ribbon structure.
6. The lead of claim 1, wherein the second pattern is a
two-dimensional array and the plurality of second electrodes are
separated by electrically insulative material associated with the
second side of the ribbon structure.
7. The lead of claim 1, wherein the first electrodes and the second
electrodes have a length in range of 2 mm to 4 mm and a width in
the range of 0.25 mm and 2 mm.
8. The lead of claim 1, wherein the spacing between adjacent first
electrodes or adjacent second electrodes along the length of the
ribbon structure is no more than two times the length of the first
electrodes or the second electrodes.
9. The lead of claim 1, wherein the spacing between adjacent first
electrodes or adjacent second electrodes across the width of the
ribbon structure 506 is no more than two times the width of the
first electrodes or the second electrodes.
10. The lead of claim 1, wherein the ribbon structure is
characterized by a length in the range of 3 cm to 8 cm and a width
in the range of 2 mm to 5 mm.
11. The lead of claim 1, wherein the ribbon structure is
characterized by a thickness in the range of 0.25 mm to 1 mm.
12. The lead of claim 1, wherein the first pattern and the second
pattern arrange the plurality of first electrodes and the plurality
of second electrodes relative to each other so that no first
electrode aligns with a second electrode along an axis extending
perpendicular through either a first electrode or a second
electrode and through the ribbon structure.
13. The lead of claim 1, wherein the first pattern and the second
pattern arrange the plurality of first electrodes and the plurality
of second electrodes relative to each other so that a first
electrode aligns with a second electrode along an axis extending
perpendicular through either a first electrode or a second
electrode and through the ribbon structure.
14. The lead of claim 1, further comprising a proximal-end region
having a lead interface structure configured to mechanically couple
to and subsequently decouple from an interface structure of a
therapy module.
15. The lead of claim 14, wherein the lead interface structure
comprises a plurality of electrical contacts, each electrically
coupled to one of the first or second electrodes.
16. The lead of claim 1, wherein the plurality of first electrodes
and the plurality of second electrodes are separately formed and
integrated into the ribbon structure.
17. The lead of claim 1, wherein the plurality of first electrodes
and the plurality of second electrodes are formed on the ribbon
structure by thin film deposition.
18. The lead of claim 1, further comprising at least one sensor
associated with the ribbon structure.
19. The lead of claim 18, wherein the at least one sensor comprises
at least one of at least one temperature sensor arranged within the
first side of the ribbon structure and at least one temperature
sensor arranged within the second side of the ribbon structure.
20. The lead of claim 1, wherein the ribbon structure further
comprises a layer of insulative material sandwiched between the
plurality of first electrodes on the first side of the ribbon
structure, and the plurality of second electrodes on the second
side of the ribbon structure.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. Utility patent
application Ser. No. 16/409616, filed May 10, 2019, entitled
SYSTEM, DEVICES, AND METHODS COMBINING SPINAL STABILIZATION AND
NEUROMODULATION and claims the benefit of and priority to U.S.
Provisional Patent Application Ser. No. 62/670,034, filed May 11,
2018, entitled "Method and Apparatus to Deliver Neuromodulation to
the Spine", the entire disclosures of which are incorporated herein
by reference.
TECHNICAL FIELD
[0002] The present disclosure relates generally to the treatment of
chronic back pain, and more particularly, to systems, devices, and
methods that treat chronic back pain through concurrent provision
of spinal stabilization and neuromodulation.
BACKGROUND
[0003] Chronic lower back pain is caused by spinal instability that
results from conditions such as degenerative disc disease,
fractures, spinal stenosis, and spondylolisthesis (slippage of the
bony vertebra). Typically, a patient suffering from chronic lower
back pain is first treated using conservative pain management
techniques, such as exercise, physical therapy, injections and
medication. When conservative pain management does not effectively
treat a patient's pain symptoms, a more aggressive pain management
approach may be taken.
[0004] In a more aggressive pain management scenario, a patient may
undergo a surgical spinal fusion procedure that utilizes a fixation
device to immobilize and straighten the back to restore stability
to the back and relieve pain. Spinal fusion is a surgical technique
to stabilize the spinal column. Fusion surgery is designed to
create solid bone between the adjoining vertebrae, eliminating any
movement between the bones. The goal of the surgery is to address
mechanical aspects of pain and/or neural compression or irritation
as a cause of pain. Spinal fusion may be recommended for cases of
spinal instability such as spondylolisthesis, degenerative disc
disease or recurrent disc herniations, spinal infections (e.g.
tuberculosis or pyogenic), fractures of spine and spinal
tumors.
[0005] With reference to FIG. 1A, an example fixation device
utilized for spinal fusion includes a pair of pedicle screws and a
rod. During a spinal fusion surgical procedure, access to a space
between adjacent vertebrae is gained, for example, through a
laminotomy. A bone material, called a bone graft, is placed into
the space to help promote the fusion of the vertebrae. After
placement of the bone graft, the fixation device is implanted to
stabilize the back during the time it takes for fusion to complete.
To this end, the screw thread portion of each of the pedicle screws
is screwed into a respective pedicle of a respective vertebrae,
leaving the screw head portion exposed. A rigid and inflexible rod
is then placed in and between the screw heads and secured in place
by at each screw head by a screw-head nut. The rod-and-screw
fixation device prevents relative movement between the adjacent
vertebrae to which it is attached.
[0006] Spinal fusion, however, does not always relieve pain as
intended. In fact, residual pain occurs after up to 40% of spinal
surgeries, costing an average of $20 billion US health care dollars
per year and severely reducing quality of life for patients.
Residual pain after a traditional back surgery often leaves a
patient seeking other aggressive pain-relieving therapies such as
oral opioids, spinal injections, radiofrequency (RF) nerve ablation
or spinal cord stimulation, or eventually pursuing another spinal
surgery to relieve their pain. This condition, also referred to as
failed back surgery syndrome, is one of the primary indications for
traditional spinal cord stimulation.
[0007] Since spinal cord stimulation is well known to effectively
treat chronic neuropathic pain it suggests that such neuropathic
pain exists in patients with spinal instability. The genesis of
neuropathic pain often arises as a result of direct damage and/or
irritation to nerves and is different from the natural
mechanical/nociceptive pain (i.e. telling us something is wrong in
our body) that may also exist in combination with spinal
instability. The neuropathic component of the pain may have arisen
as a result of the patient's chronic instability and spinal nerve
compression and/or irritation within the weakened/unstable spinal
vertebrae at the spinal level affected prior to their surgery.
Additional neuropathic pain can arise from the surgical cutting
(skin, muscle, bones, nerves) to perform the surgery. So
neuromodulation can treat this pre-existing neuropathic pain and it
will also treat or even prevent any subsequent neuropathic pain
that arises from the surgery.
[0008] With reference to FIG. 1B, an example spinal cord
stimulation system utilized for treating chronic back pain includes
a pulse generator and a pair of leads. During the implant
procedure, the electrode-bearing ends of the leads are
percutaneously implanted into the epidural space of the spine, to
place the electrodes in the area of the nerves that are to be
neuromodulated. The portion of the leads outside of the epidural
space are then tunneled beneath the skin down to, and then
connected to the pulse generator. The pulse generator is implanted
in a subcutaneous pocket formed to a side of the spinal column.
[0009] Most patients, however, are not indicated for spinal cord
stimulation until they have failed many other therapies, and it is
often 2-5 years after their initial spinal fusion before spinal
cord stimulation is offered, resulting in prolonged disability and
morbidity. As a result, many patients do not experience adequate
relief and often become reliant on addictive opioids in a futile
attempt to reduce their remaining pain. This contributed to the 2.1
million people who had an opioid use disorder, 11.5 million people
who abused prescription opioids in 2016 and the annual economic
cost of the opioid crisis, estimated to be over $500 billion in
2015. Due to the extent of this public health epidemic, it remains
critical to exhaust all other methods of pain management before
turning to opioids, particularly since no clinical studies have
confirmed the effectiveness of long-term opioid usage on chronic
back pain.
[0010] It is therefore desirable to reduce or eliminate the
separation in time between surgical spinal procedures and
neurostimulation implant procedures to enable the provision of
neuromodulation therapies as soon as possible after occurrence of a
failed hack surgery. It is also desirable to have a pain management
system that combines spinal fixation hardware and neuromodulation
components to thereby provide mechanical/nociceptive pain therapy
concurrent with neuropathic pain therapy. The concepts disclosed
below address these desires and others.
SUMMARY
[0011] An implantable medical lead for neuromodulating nerve
structures includes a ribbon structure having a first side and a
second side opposite the first side. A plurality of first
electrodes are associated with the first side and arranged in a
first pattern, while a plurality of second electrodes associated
with the second side and arranged in a second pattern. The ribbon
structure is configured to transition from a planar state to a
non-planar state upon the application of a force and to remain in
the non-planar state upon removal of the force. For example, the
non-planar state may be an undulating state during which the ribbon
structure bends in at least one curve or in a series of successive
curves in alternating directions along the longitudinal axis of the
ribbon structure. In one finer aspect of the lead, the undulating
state comprises at least one curve having a radius of curvature in
the range of 1 mm and 3 mm. In another example, the non-planar
state may be a twisted state during which the edges of the ribbon
structure along the length of the ribbon structure curve about the
longitudinal axis of the ribbon structure. The ability of the
ribbon structure to assume different non-planar states is a
function of the configuration of the ribbon structure, including
the material properties of the ribbon structure, the thickness of
the ribbon structure, and the electrode size, interelectrode
spacing and electrode patterns.
[0012] An implantable neuromodulation device for implant with a
spinal stabilization device includes a therapy module and a lead.
The spinal stabilization device includes a pair of pedicle screws,
each having a screw-head with a screw-head cavity, and the therapy
module includes a housing having a form factor comprising at least
one feature configured to mate with a corresponding feature of a
screw-head of one of the pedicle screws. The respective features
mate in a manner that enables the therapy module to mechanically
couple to and subsequently decouple from the screw-head of the
pedicle screw. For example, the mating may be through threaded
engagement or friction. The lead includes a distal-end region
having a plurality of electrodes and a proximal-end region having a
lead interface structure configured to mechanically and
electrically couple to and subsequently decouple from the therapy
module.
[0013] A pain management system includes a spinal stabilization
device and a neuromodulation device. The spinal stabilization
device includes a rod, a plurality of pedicle screws each having a
screw-head defining a screw-head cavity configured to receive a
portion of the rod, and a corresponding plurality of inserts
configured to engage with the inner wall of the cavity to secure
the rod in place in the cavity. The neuromodulation device includes
a therapy module comprising electronics packaged within a housing.
The housing has a form factor having at least one feature
configured to mate with a corresponding feature of the screw-head
of one of the plurality of pedicle screws. The respective features
mate in a manner that enables the therapy module to mechanically
couple to and subsequently decouple from the screw-head of the
pedicle screw. The pain management system as such, simultaneously
addresses three types of pain: (1) mechanical/nociceptive pain
caused from poor alignment or instability, (2) neuropathic pain,
caused by damage of the nerve trunk and over sensitization of
nerves in the brain and spinal cord, and (3) post-surgical pain,
which is inherently caused by the surgical procedure.
[0014] A method of treating chronic back pain includes stabilizing
a pair of vertebrae of the back of a patient healing from spinal
fusion and neuromodulating one or more nerve structures associated
with the pair of vertebrae while the patient is healing from the
spinal fusion. The stabilizing treats nociceptive pain resulting
from misalignment of the vertebrae or compression of nerves between
or adjacent the vertebrae, while the neuromodulating treats
neuropathic pain resulting from damage of the nerve trunk and over
sensation of nerves in the brain and spinal cord.
[0015] A method of implanting a pain management system having a
spinal stabilization hardware and a neuromodulation device includes
creating direct access to nerve structures while implanting the
spinal stabilization hardware, and placing a lead on or adjacent to
target nerve structures under direct visual access. The method
further includes mechanically coupling a therapy module of the
neuromodulation device to a component of the spinal stabilization
hardware; and mechanically and electrically coupling a lead of the
neuromodulation device the therapy module.
[0016] It is understood that other aspects of apparatuses and
methods will become readily apparent to those skilled in the art
from the following detailed description, wherein various aspects of
apparatuses and methods are shown and described by way of
illustration. As will be realized, these aspects may be implemented
in other and different forms and its several details are capable of
modification in various other respects. Accordingly, the drawings
and detailed description are to be regarded as illustrative in
nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Various aspects of system, device, and methods will now be
presented in the detailed description by way of example, and not by
way of limitation, with reference to the accompanying drawings,
which are not to scale, wherein:
[0018] FIG. 1A is an illustration of an implanted spinal fixation
device utilized for spinal fusion that includes a pair of pedicle
screws and a rod.
[0019] FIG. 1B is an illustration of an implanted spinal cord
stimulation system utilized for treating chronic back pain that
includes a pulse generator and a pair of leads.
[0020] FIG. 2 is a schematic illustration of a pain management
system implanted at an upper lumbar spinal level that includes a
pair of spinal fixation devices including pedicle screws and rod,
and a neuromodulation device that includes a ribbon lead and a
therapy module configured to be mechanically coupled to and
decoupled from a pedicle screw.
[0021] FIG. 3A is a schematic cross-section of FIG. 2 along line
3A-3A illustrating the therapy module of the neuromodulation device
mechanically coupled to the pedicle screw of a spinal fixation
device.
[0022] FIG. 3B is a schematic cross-section of FIG. 2 along line
3B-3B illustrating a bilateral placement of the ribbon lead of the
neuromodulation device.
[0023] FIG. 3C is a schematic cross-section illustrating unilateral
placement of a ribbon lead an upper lumbar spinal level.
[0024] FIG. 3D is a schematic cross-section illustrating unilateral
placement of a ribbon lead at a lower lumbar spinal level.
[0025] FIG. 4 is an illustration of components of the pain
management system of FIG. 2 including a pedicle screw, a therapy
module coupled to the screw-head of the pedicle screw, and a ribbon
lead.
[0026] FIG. 5A is an illustration of the ribbon lead of FIG. 4
including an electrode-bearing ribbon structure having electrodes
on both sides.
[0027] FIGS. 5B, 5C and 5D are top, bottom and side views of the
ribbon lead of FIG. 5A.
[0028] FIG. 5E is an illustration of a portion of the ribbon
structure of the ribbon lead of FIG. 5A where the electrodes on
opposite sides are staggered or offset relative to each other.
[0029] FIG. 5F is an illustration of a portion of the ribbon
structure of the ribbon lead of FIG. 5A where the electrodes on
opposite sides are stacked or aligned relative to each other.
[0030] FIG. 5G is an illustration of the ribbon lead of FIG. 5A
where the ribbon structure has been subjected to bending forces and
has assumed an undulated configuration along its longitudinal
axis.
[0031] FIG. 5H is an illustration of the ribbon lead of FIG. 5A
where the ribbon structure has been subjected to bending forces and
has assumed an undulated configuration along its longitudinal axis
having sharper curves, e.g. lower radius of curvature, than the
curves of FIG. 5G.
[0032] FIG. 5I is an illustration of the ribbon lead of FIG. 5A
where the ribbon support has been subjected to twisting forces and
has assumed a twisted configuration about its longitudinal
axis.
[0033] FIG. 6A is a schematic illustration of the therapy module of
FIG. 4 coupled to the screw-head of the pedicle screw.
[0034] FIGS. 6B and 6C are alternate embodiments of the therapy
module of FIG. 6A.
[0035] FIG. 6D is a schematic illustration of the electronic
components of anyone of the therapy modules of FIGS. 6A, 6B and
6C.
[0036] FIG. 7 is a schematic illustrations of alternate embodiments
of a therapy module coupled to the screw-head of the pedicle
screw.
[0037] FIG. 8 is a schematic illustration of components of an
alternate embodiment of a pain management system including a
pedicle screw, a therapy module coupled to the screw-head of the
pedicle screw, and a ribbon lead.
[0038] FIG. 9 is a block diagram of the system of FIG. 1A,
including an implantable medical device comprising therapy module
associated with one or more leads, a health information module
associated with one or more sensors, and one or more external
devices including an therapy controller and a patient interface
device.
[0039] FIG. 10 is a block diagram of the therapy module and leads
of FIG. 9.
[0040] FIG. 11 is a block diagram of the health information module
and associated sensors of FIG. 9.
DETAILED DESCRIPTION
[0041] Disclosed herein is an implantable pain management system
that includes spinal stabilization hardware and a neuromodulation
device having a therapy module component configured to mechanically
couple to and subsequently decouple from a component of the spinal
stabilization hardware. In one embodiment, the spinal stabilization
hardware is in the form of a spinal fixation device that includes a
pair of pedicle screws and a rod, and the therapy module is
configured to mechanically coupled to and decoupled from a pedicle
screw. The neuromodulation device also includes a lead having a
ribbon like electrode-bearing region at its distal end and an
interface structure at its proximal end that is configured to
mechanically coupled to and decoupled from the therapy module.
Given the coupling and decoupling capabilities of the therapy
module and lead, the therapy module may be replaced if necessary by
simply decoupling the lead from the therapy module and decoupling
the therapy module from the pedicle screw.
[0042] The distal-end region of the ribbon lead includes a ribbon
structure that is very flexible and is configured to transition
from a substantially planar shape to a non-planar shape upon the
application of a three and to remain in the non-planar state upon
removal of the force. This allows the ribbon structure to assume
and retain various shapes, including a shape that undulates along
the length of the distal-end region or a shape that twists along
the length of the distal-end region. Configured as such, the
distal-end region of the lead is able to weave around and between
spinal nerve structures and branches and to assume shapes that
conform to the anatomy. Furthermore, electrodes may be located on
each side of the distal-end region. This is advantageous in that if
the distal-end region of the lead were to flip such that electrodes
on one side of the region were no longer properly positioned to
deliver stimulation energy to a nerve structure, the electrodes on
the opposite side would be properly positioned and could serve as
stimulating electrodes.
[0043] Also disclosed herein is a method of treating chronic back
pain that includes simultaneously stabilizing vertebrae of the back
during spinal fusion to treat nociceptive pain resulting from
misalignment of the vertebrae or compression of nerves between or
adjacent the vertebrae, and neuromodulating one or more nerve
structures associated with the vertebrae to treat neuropathic pain
resulting from damage of the nerve trunk and over sensation of
nerves in the brain and spinal cord. Delivering neuromodulation at
the same time as a spinal stabilization allows for a more effective
and holistic treatment of a patient's pain ensuring better
outcomes. The method disclosed herein allows for the two
complementary therapies of spinal stabilization and neuromodulation
to be delivered at the same time within the same anatomical space.
The synergistic use of mechanical stabilization with
neurostimulation might also contribute to relieving the acute pain
associated with the spine surgery.
[0044] Also disclosed herein is a method of implanting a pain
management system that includes spinal stabilization hardware and a
neuromodulation device having a therapy module component configured
to mechanically couple to and decouple from a component of the
spinal stabilization hardware. Spinal stabilization hardware is
implanted as part of a spinal fusion procedure. As part, of this
surgical procedure, open access to nerve structures in the area of
the fusion is provided and a lead of a neuromodulation device is
placed at or near the nerve structures. Subsequently, the therapy
module is mechanically coupled to a component of the spinal
stabilization hardware and the lead is mechanically and
electrically coupled to the therapy module.
[0045] Regarding lead placement, because the spine is exposed
during the spinal fusion procedure, some nerve structures and
branches may be directly visible to the spine surgeon. This enables
direct placement of the lead by the surgeon without the need for
implant tools such as catheters or sheaths. For example, using a
transforaminal approach, the distal-end of the ribbon lead may
weave through and around nerve structures, including for example,
ventral roots, dorsal roots, dorsal root ganglia (DRG) and the
spinal cord. Stimulation could also be delivered to other aspects
of the spinal nerve from more peripheral rami branches or more
central to the dorsal root entry zone (DREZ) or spinal thalamic
tract. Multiple nerve levels could be targeted bilaterally to cover
the patient's painful dermatomes during the spine surgery with easy
surgical access and anatomical visibility.
[0046] In some cases, spinal fusion is prescribed separately from
neuromodulation, with spinal fusion typically being prescribed
first in time, with neuromodulation being delayed until other
treatment options are exhausted. The time between a spinal fusion
procedure and a neuromodulation device implant procedure in these
cases may be 6-10 years. It can also be 20 or more years due to
lack of awareness or specialist referral access, opioid issues,
etc. In other cases, however, a patient may be prescribed both
spinal fusion and neuromodulation. Traditionally, however, the
neuromodulation device implant procedure and the spinal fusion
procedure are performed separately for any of several reasons. For
example, implantation of a traditional neuromodulation device, such
as shown in FIG. 1B, may fall outside the spine surgeon's
traditional practice, thus requiring the patient to be referred to
a pain specialist that implants neuromodulation devices. Thus, even
in the rare case of concurrent prescription of the spinal fusion
and neuromodulation, the time between a spinal fusion procedure and
a neuromodulation device implant procedure may range between 3
months to 1 year. Given such separations in time, during later
implantation of a neuromodulation device it is often difficult to
navigate the spine space to implant neurostimulation leads due to
scar tissue build-up. Thus, it is advantageous to perform both
procedures in a single surgical setting, as disclosed herein.
[0047] Pain Management System
[0048] With reference to FIG. 2, an implantable pain management
system 200 is shown implanted at an upper lumbar spinal level. The
pain management system 200 includes spinal hardware in the form of
a pair of spinal fixation devices 202, 204. The spinal fixation
devices 202, 204 are configured to stabilize the spine as part of a
spinal fusion procedure. The pain management system 200 also
includes a neuromodulation device 206. The neuromodulation device
206 is configured to delivery energy to one or more nerve
structures, wherein the energy results in modulation of nervous
system activity. While the neuromodulation device 206 described
herein deliver electrical stimulation to the target structure(s) as
the main output, alternate forms of energy delivery are envisioned
to modulate nerve activity, including thermal (heating or cooling),
radio frequency (RF), ultrasound (mechanical, vibrations), optic
(or optogenetic), laser, and magnetic.
[0049] Neuromodulation employs the body's natural biological
response by stimulating nerve cell activity that can influence
populations of nerves by releasing transmitters, such as dopamine,
or other chemical messengers such as the peptide Substance P, that
can modulate the excitability and firing patterns of neural
circuits. There may also be more direct electrophysiological
effects on neural membranes as the mechanism of action of
electrical interaction with neural elements. The end effect is a
"normalization" of a neural network function from its perturbed
state. Presumed mechanisms of action for neurostimulation include
depolarizing blockade, stochastic normalization of neural firing,
axonal blockade, reduction of neural firing keratosis, and
suppression of neural network oscillations at all levels of the
central nervous system. Recent functional MRI evidence suggests
that altered brain activity is associated with neuropathic pain and
that neuromodulation improves this function in association with
pain.
[0050] Continuing with FIG. 2, each of the spinal fixation devices
202, 204 includes a pair of pedicle screws 208a, 208b, 208c, 208d
and rod 210a, 210b. These spinal fixation devices 202, 204 may be
referred to herein as rod-and-screw devices. The material structure
and respective dimensions of the pedicle screws 208a, 208b, 208c,
208d and rods 210a, 210b imparts a measure of stiffness, e.g., the
extent to which an object resists deformation in response to an
applied force, that render these components inflexible in their
implanted operating environment. To this end the pedicle screws
208a, 208b, 208c, 208d may be formed of, for example, stainless
steel or titanium-alloy and are dimensioned and shaped to be
screwed into honey structure of the vertebrae. The rod 210a, 201b
may also be formed of, for example, stainless steel or
titanium-alloy and are and are dimensioned and shaped to be fixedly
secured between adjacent pedicle screws implanted at different
spinal levels. Upon implant of the spinal fixation devices 202,
204, the adjacent vertebrae into which the pedicle screws 208a,
208b, 208c, 208d are screwed are rendered immobile relative to each
other by the rigid rod 210a, 210b spanning the screws.
[0051] The neuromodulation device 206 includes a ribbon lead 212
and a therapy module 214. The therapy module 214 is configured to
mechanically couple to and subsequently decouple from a pedicle
screw 208a. Likewise, the ribbon lead 212 is configured to
mechanically couple to and subsequently decouple from the therapy
module 210 through respective interface structures 216, 218
associated with the ribbon lead and the therapy module. When
mechanically coupled to the therapy module 210, one or more
electrodes at the distal end of the ribbon lead 212 are
electrically coupled to circuitry within the therapy module
214.
[0052] The coupling and decoupling between respective components is
such that the decoupling of one component from another does not
alter or damage the structural integrity of either component. In
this sense, the components may be described as being removably
coupled to each other, where decoupling involves the application of
minimal force. For example, the ribbon lead 212 may be decoupled
from the therapy module 214 by manually pulling a connector pin of
the lead interface structure 216 out of a corresponding connector
port of the therapy module interface structure 218.
[0053] While the pain management system 200 shown in FIG. 2
includes only one therapy module 214 and one ribbon lead 212,
additional therapy modules and ribbon leads may be included in the
system. For example, in one configuration, one or more additional
therapy modules may be mechanically coupled to one or more of the
other pedicle screws 208b, 208c, 208d. Each additional therapy
module may, in turn, be mechanically and electrically coupled to a
lead. The lead to which an additional therapy module is connected
may be the same ribbon lead 212 as the one that is already
connected to the therapy module 214. To this end, the ribbon lead
212 may connect to the additional therapy module through one of the
additional connector pins of the lead interface structure 216,
Alternatively, the lead to which an additional therapy module is
connected may be an additional lead (not shown). In another
configuration, one or more additional ribbon leads may be
mechanically and electrically coupled to a single therapy module
214. In this case, the therapy module 214 would include a
therapy-module interface structure 218 with multiple connector
ports, each configured to receive a respective connector pin of a
ribbon lead.
[0054] Having thus generally described the components of the pain
management system 200, a description of various placements of the
pain management system relative to the spinal anatomy are provided
below, followed by a more detailed description of the components of
the neuromodulation device of the pain management system.
[0055] Placements of Pain Management System
[0056] With reference to FIG. 3A, which is a cross-section of FIG.
2 along line 3A-3A, the pedicle screw 208a of the pain management
system 200 of FIG. 2 is shown screwed into and extending from the
posterior side 302 of the vertebrae to the anterior side 304. In
doing so, a threaded portion 306 of the pedicle screw 208a passes
through honey structure of the vertebrae including the vertebral
arch lamina 308, the pedicle 310 and into the anterior body 312. A
screw-head 314 of the pedicle screw 208a is exposed at the
posterior side 302. The screw-head 314 is U-shaped and defines a
cavity into which the rod 210a is placed. A threaded insert 316
engages with screw threads in the interior wall of the cavity and
is rotated to engage with and secure the rod in place. The therapy
module 214 of the neuromodulation device is mechanically coupled to
the screw-head 314 of the pedicle screw 208a. For example, as
described further below with reference to FIGS. 6A, 6B and 6C, the
therapy module 214 may mechanically engage with the screw-head 314
through respective screw threads or by friction fit between
respective surfaces of the therapy module and the screw-head.
[0057] With reference to FIG. 3B, which is a schematic
cross-section of FIG. 2 along line 3B-3B, the ribbon lead 212 of
the neuromodulation device is shown placed adjacent various nerve
structures in a bilateral arrangement. In this regard, bilateral
refers to a lead placement that positions electrodes on or adjacent
nerve structure on both sides of the spinal column midline. In the
example placement shown in FIG. 3B, the electrode-bearing
distal-end region of the ribbon lead 212 extends through a
vertebral foramen 318 on a first side of the spinal cord 320, along
a path that weaves the distal-end region through and around nerve
structures such that portions of the distal-end region are
positioned on or adjacent one or more of: a first dorsal root
ganglion 322, a first ventral root 324, the ventral side of the
spinal cord 320, a second ventral root 326, and a second dorsal
root ganglion 328. Placement of the ribbon lead 212 as such enables
neuromodulation of various nerves structures together with
stimulation of vertebral bone or cartilage, the latter of which
promotes bone growth/healing of a spinal fusion.
[0058] With reference to FIG. 3C, the ribbon lead 212 of the
neuromodulation device is shown placed adjacent various nerve
structures in a unilateral arrangement. In this regard, unilateral
refers to a lead placement that positions electrodes on or adjacent
nerve structure on one side of the spinal column midline. In the
example placement shown in FIG. 3C, the electrode-bearing
distal-end region of the lead extends through a vertebral foramen
318 on a first side of the spinal cord 320, along a path that
weaves the distal-end region through and around nerve structures
such that portions of the distal-end region are positioned on or
adjacent one or more of: a first spinal nerve 330, a first dorsal
root ganglion 322, a first dorsal root 332, and a portion of the
dorsal side of the spinal cord 320. Placement of the ribbon lead
212 as such enables neuromodulation of various nerves structures
together with stimulation of vertebral bone or cartilage, the
latter of which promotes bone growth/healing of a spinal
fusion.
[0059] With reference to FIG. 2, placement of the lead as shown in
FIGS. 3B and 3C may occur during implant of the spinal fixation
devices 202, 204. To this end, during spinal fusion a laminectomy
and/or laminotomy may be performed to gain access to a spinal disc.
As a result, a surgical opening 220 is available through which a
surgeon has direct access to the nerve structures. Accordingly, the
distal-end region of the ribbon lead 212 may be placed and weaved
through and around the nerve structures without the need for
traditional lead delivery tools. For example, in the open access
procedure afforded by the surgical opening 220, the surgeon does
not have to access the spinal column region using a percutaneous
sheath or catheter, nor does the surgeon have to advance the lead
through such delivery tools.
[0060] With reference to FIG. 3D, which is a schematic
cross-section of a ribbon lead 212 implanted at a lower lumbar
spinal, the ribbon lead 212 of the neuromodulation device is placed
adjacent various nerve structures in a unilateral arrangement. In
the example placement shown in FIG. 3D, the electrode-bearing
distal-end region of the lead extends through a vertebral foramen
318 on a first side of the spinal cord 320, along a path that
weaves the distal-end region through and around nerve structures
such that portions of the distal-end region are positioned on or
adjacent one or more of: a first spinal nerve 330, a first dorsal
root ganglion 322, a first dorsal root 332, and a portion of the
dorsal side of the Conus Medularis/Cauda equina 340. Placement of
the ribbon lead 212 as such enables neuromodulation of various
nerves structures together with stimulation of vertebral bone or
cartilage, the latter of which promotes bone growth/healing of a
spinal fusion.
[0061] Neuromodulation Device
[0062] With reference to FIG. 4, as disclosed above, the
neuromodulation device 206 disclosed herein includes a ribbon lead
212 and a therapy module 214. The therapy module 214 is configured
to mechanically coupled to and decoupled from the screw-head 314 of
a pedicle screw 208a. Likewise, the ribbon lead 212 is configured
to mechanically couple to and subsequently decouple from the
therapy module 214 through respective interface structures 216, 218
associated with the ribbon lead and the therapy module. When
mechanically coupled to the therapy module 210, one or more
electrodes at the distal end of the ribbon lead 212 are
electrically coupled to circuitry within the therapy module
214.
[0063] Ribbon Lead
[0064] With reference to FIGS. 5A-5D the ribbon lead 212 includes a
distal-end region 502 and proximal-end region 504. The distal-end
region 502 includes a flexible, thin ribbon structure 506 having a
plurality of first electrodes 508 arranged within its first side
510 and a plurality of second electrodes 512 arranged within its
second side 514. The flexible, thin ribbon structure 506 may be
made of a flexible biocompatible polymer (e.g., silicone) having a
Shore hardness selected provide the ribbon structure a high degree
of flexibility, to make the ribbon structure soft, floppy, and
ductile. To this end, the Shore hardness may be on the order of
60A. The ribbon structure 506 may have a thickness in the range of
0.25 mm to 1 mm. The respective electrodes 508, 512 on each side
are electrically isolated from each other by insulative material of
the ribbon structure 506. Furthermore, the ribbon structure 506 may
include a layer of insulative material that is sandwiched between
the first electrodes 508 on the first side 510 and the second
electrodes 512 on the second side 514 to prevent electrical
interference between electrodes on opposite sides.
[0065] In the example ribbon lead 212 shown in FIGS. 5A-5D, the
ribbon structure 506 includes two rows of electrodes 508 on its
first side 510 and two rows of electrodes 512 on its second side
514, with each row having sixteen electrodes. Thus, each side of
the ribbon structure 506 has thirty-two electrodes 508, 512
arranged in a pattern corresponding to a 2-by-16, two-dimensional
array. Of course, different numbers of electrodes may be included
in the ribbon structure 506 and different two-dimensional array
patterns may be formed by the electrodes. For example, in other
embodiments of the ribbon lead 212, the ribbon structure 506 may
include sixteen electrodes on each side arranged in a 2-by-8
two-dimensional array for a total of thirty-two electrodes, or
twenty-four electrodes on each side arranged in a 2-by-24
two-dimensional array for a total of forty-eight electrodes.
[0066] The electrodes 508, 512 are preferably formed of a
non-corrosive, highly conductive material. Examples of such
material include stainless steel, MP35N, platinum., and platinum
alloys. The electrodes 508, 512 may be separately formed and
integrated into the silicone material of the ribbon structure 506.
In this case, the electrodes 508, 512 may have a thickness in the
range of 0.05-0.2 mm. Alternately, the ribbon structure 506 may be
manufactured using thin film technology, in which case the
electrodes 508, 512 may formed on respective sides of a substrate
layer forming part of the ribbon structure, using thin film
deposition. In this case, the electrodes 508, 512 may have a
thickness in the range of 0.01-0.1 mm. In either case, the surfaces
the electrodes 508, 512 are substantially flush with the surfaces
of the ribbon structure 506. In another example. the ribbon
structure 506 could be a custom printed lead based on individual
patient anatomy (e.g., selective nerve root anatomy). The anatomy
could be obtained by scanning the patient's nerve/spine area to get
the dimensions and then taking the contour and dimension input to
custom print the lead.
[0067] One or more sensors may be associated with the ribbon
structure 506. For example, the ribbon structure 506 may have a
plurality of first temperature sensors 509 arranged within its
first side 510 and a plurality of second temperature sensors 513
arranged within its second side 514, for providing temperature
feedback signals to the therapy module 214. Each temperature sensor
may be associated with a group or cluster of electrodes 508,
512.
[0068] The ribbon structure 506 is configured to have utmost
flexibility to enable placement of electrodes at one or more nerve
structures during an open surgical procedure. In addition to the
above described material composition and thickness of the ribbon
structure 506, additional features of the ribbon structure impart
the desired flexibility. These additional features include: 1) the
arrangement of the electrodes 508, 512 relative to each other on
the same side of the ribbon structure, 2) the arrangement of the
electrodes 508, 512 relative to each other on the opposite sides of
the ribbon structure, and 3) the size of the electrodes and the
interelectrode spacing.
[0069] Same-Sided Electrode Arrangement
[0070] With reference to FIGS. 5B and 5C, the electrodes 508, 512
on each side 510, 514 are arranged in a pattern selected to improve
flexibility of the ribbon structure 506. To this end, while the
electrodes 508, 512 are substantially aligned along the length of
the ribbon structure 506, they are offset or staggered relative to
each other across the width of the ribbon structure. Thus, the
ribbon structure 506 is devoid of rigid regions that would
otherwise result if two electrodes 508, 512 on the same side were
aligned side-by-side across the width. This staggering of
same-sided electrodes improves the flexibility of the ribbon
structure 506 both along it length and across its width. In another
configuration, the electrodes 508, 512 are substantially aligned
along the length of the ribbon structure 506 and across the width
of the ribbon structure. Thus, the ribbon structure 506 has
alternates along its length between regions that are devoid of any
electrodes and thus highly flexible, and regions having
side-by-side electrodes across its width that are less
flexible.
[0071] Opposite-Sided Electrode Arrangement
[0072] With reference to FIG. 5E, the arrangement of respective
electrodes 508, 512 on respective sides 510, 514 of the distal-end
region 502 of the ribbon lead 212 may be such that the electrodes
on opposite sides are staggered or offset relative to each other.
In other words, the first pattern of first electrodes 508 and the
second pattern of second electrodes 512 arrange the plurality of
first electrodes and the plurality of second electrodes relative to
each other so that no first electrode aligns with a second
electrode along an axis 515 extending perpendicular through an
electrode and through the ribbon structure 506.
[0073] In an alternate configuration, shown in FIG. 5F, the
arrangement of respective electrodes 508, 512 on respective sides
510, 514 of the distal-end region 502 of the ribbon lead 212 may be
such that the electrodes on opposite sides are stacked or aligned
relative to each other. In other words, the first pattern of first
electrodes 508 and the second pattern second electrodes 512 arrange
the plurality of first electrodes and the plurality of second
electrodes relative to each other so that a first electrode aligns
with a second electrode along an axis 517 extending perpendicular
through and electrode and through the ribbon structure.
[0074] Each of these arrangements has its advantages. For example,
the staggered arrangement shown in FIG. 5E provides greater spacing
between opposite-sided electrodes, thus reducing current leakage
between the electrodes. The staggered arrangement may also provide
for easier manufacturing using thin film plating technology. The
stacked arrangement shown in FIG. 5F provides ribbon structure 506
with regions that are devoid of metal electrodes on each of its
side, thus allowing for more flexibility of the distal-end
region.
[0075] While the foregoing describes alternate configurations where
the opposite-sided electrodes are either aligned or offset, other
arrangement are possible. For example, opposite-sided electrodes
may be partially aligned such that only portions of the electrodes
overlap. In an example of one such configuration, opposite-sided
electrodes may be arranged so that there is a 50% overlap between
the respective surfaces of the electrodes.
[0076] Electrode Size and Spacing
[0077] In the ribbon lead 212 illustrated in FIG. 5A-5E, the
electrodes 508, 512 are long and narrow in the shape of a hockey
ring. In this configuration, the electrodes 508, 512 may have a
length in the range of 2 mm to 4 mm and a width in the range of
0.25 mm and 2 mm. The spacing between adjacent electrodes along the
length of the ribbon structure 506 is no more than two times the
length of the electrodes. The spacing between adjacent electrodes
across the width of the ribbon structure 506 is no more than two
times the width of the electrodes. The ribbon lead 212, however,
does not require electrodes in the shape and size just described.
The electrodes 508, 512 may have different shapes, including for
example square, oval, circular, etc.
[0078] The electrode size and interelectrode spacing according to
representative embodiments provide sufficient resolution to control
the stimulation of target nerve structure, such as those described
above with reference to FIGS. 3B and 3C. Additionally, the
electrode clusters 516a-d, 516e-h provide a degree of positional
tolerance during the surgical placement of distal-end region 502 of
the ribbon lead 212 in the area of the spinal column, because it is
likely that at least one of the electrode clusters can be
appropriately placed to stimulate a target nerve structure. Also,
if the distal-end region 502 is displaced relative to a target
nerve structure subsequent to implantation due to migration or
flipping of the ribbon structure 506, the stimulation applied to
that target nerve structure can be shifted to different electrodes
508, 512 on the same side of the ribbon structure (in the case of
longitudinal movement of the ribbon structure) or to electrodes on
the opposite side of the ribbon structure (in the case of flipping
or twisting of the ribbon).
[0079] With reference to FIGS. 5A-5D, in one embodiment the
thirty-two electrodes 508, 512 on each side are grouped into four
electrodes clusters, each having eight electrodes. Thus, the ribbon
lead 212 has a total of eight electrode clusters, with four
clusters 516a-d on the first side and four clusters 516e-h on the
second side. In one configuration, adjacent electrode clusters
516a-d, 516e-h on each side are separated from each other by an
area of insulative material 518a-c, 518d-f. The areas of insulative
material 518a-c, 518d-f between adjacent electrode clusters 516a-d,
516e-h provide the distal-end region 502 of the ribbon lead 212
with regions of higher flexibility. Specifically, the metal
structure of the electrodes 508, 512 makes those areas of the
distal-end region 502 corresponding to the electrode clusters
516a-d, 516e-h somewhat less flexible than the electrode-free areas
of the distal-end region 502 corresponding to the area of
insulative material 518a-c, 518d-f.
[0080] While the embodiment of the ribbon structure 506 depicted in
FIGS. 5A-5D includes electrode clusters 516a-d, 516e-h that are
spaced apart, such spacing is optional. Accordingly, in other
embodiments, the electrodes 508, 512 are evenly spaced along the
length of the ribbon structure 506. The electrodes 508, 512 may
still be grouped into clusters, however, such groupings are
functional in nature--not physical. Thus, as used herein the term
"cluster" does not confer any sort of spacing requirement between
groups of electrodes.
[0081] Placement of the Lead
[0082] With continued reference to FIG. 5A-5D, the distal-end
region 502 may have one of several lengths (L) depending on the
intended placement application of the ribbon lead 212. For example,
in one embodiment, a ribbon lead 212 for placement in a bilateral
arrangement as described above with reference to 313 may have a
length (L) in the range of 5 cm to 8 cm. In another embodiment, a
ribbon lead 212 for placement in a unilateral arrangement as
described above with reference to FIG. 3C may have a length (L) in
the range of 2 cm to 5 cm. The width (W) of the distal-end region
502 in the range of 2 mm to 5 mm and is sized to accommodate two
rows of electrodes. The thickness (T) of the distal-end region 502
in the range of 0.25 mm to 1 mm. Depending on the length, one or
more electrode features of the ribbon structure 506 may be
modified. For example, a shorter length ribbon structure 506 may
have fewer electrodes than a longer length ribbon structure.
Alternatively, the number of electrodes may be the same, but the
size of the electrodes in the shorter ribbon structure may be
smaller than the electrodes in the longer length ribbon. In yet
another alternative, the number and size of electrodes may be the
same, but the interelectrode spacing in the shorter ribbon
structure may be less than in the longer ribbon structure.
[0083] In some embodiments, a ribbon lead 212 can be implanted
within a patient such that the distal-end region 502 and its
associated electrodes 508, 512 are positioned at a spinal level at
or near one or more nerve structures associated with that spinal
level. For example, as previously described with reference to FIG.
3B, the distal-end region 502 of the ribbon lead may be weaved
through a spinal level such that electrodes 508, 512 are located
near the DRG on each side of the spinal cord at that level and
electrodes are located at the spinal cord.
[0084] After implantation, an electrode combination at one or more
electrode clusters may be determined that is effective for treating
pain. For example, with reference to FIG. 3B, an electrode
combination in the electrode cluster near the first dorsal root
ganglion 322 may be selected to deliver stimulation energy to first
dorsal root ganglion. Another electrode combination in the
electrode cluster near the a first ventral root 324 may be selected
to deliver stimulation energy to a first ventral root. Yet another
electrode combination in the electrode cluster near the anterior
side of the spinal cord 320 may be selected to deliver stimulation
energy to spinal cord. After the determination of the appropriate
electrodes for stimulation, the therapy module can be programmed to
deliver pulses using the first and second rows according to the
determined electrode combinations.
[0085] Interconnection of the Lead
[0086] With reference to FIG. 5A, the ribbon lead 212 includes a
lead interface structure 216 for mechanically and electrically
connecting the lead to a therapy module 214. A tubular lead body
526 extends between the ribbon structure 506 and the lead interface
structure 216. Conductors embedded within the flexible, thin ribbon
structure 506 extend through the lead body 526 to enable electrical
connection between electrodes 508, 512 and contacts associated with
the interface structure 520.
[0087] In one embodiment, the lead interface structure 216
comprises four in-line connector pins 522, each having nine
electrical contacts 524. Each connector pin 522 is switchably
connected to a one of the eight electrode clusters 516a-d, 516e-h.
The switchable connection may be provided by multiplexer circuitry
included in the lead. The multiplexer circuitry could be controlled
using a logic circuit in the ribbon lead 212 that is configured to
receive control signals from the therapy module. The logic circuit
responds to the signals by setting the multiplexer circuitry as
appropriate. Upon connection between a connector pin 522 and an
electrode cluster, eight of the nine electrical contacts 524
connect to a respective electrode 508, 512 in the connected
electrode cluster 516a-d, 516e-h. The remaining ninth electrical
contact 524 of the connector pin 522 functions as a ground or an
inactive set screw site.
[0088] Lead Functionality
[0089] Thus disclosed is a ribbon lead 212 having a two-dimensional
array of electrodes along a length of its distal-end region,
configured to have utmost flexibility to enable placement of
electrodes at one or more nerve structures during an open surgical
procedure. Because the lead is placed during an open procedure and
is intended to weave around and between nerve structures, while
also providing electrodes arrangements that enable the targeting of
multiple nerve structures and electrode shifting, design features
associated with traditional percutaneous leads or paddle leads are
avoided. For example, a paddle lead place in the epidural space is
designed so that the paddle region of the lead assumes a
substantially planar shape. While the paddle region of such leads
may be forcibly bent, the paddle region is configured such that
upon removal of such force the paddle region bounces back to its
substantially planar shape.
[0090] In the ribbon lead 212 disclosed herein, the ribbon
structure 506 is configured, via one or more of ribbon structure
thickness, electrode shape and size, interelectrode spacing,
same-sided electrode arrangements, opposite-side electrode
arrangements, to assume non-planar configurations upon the
application of a force. Such forces may include, for example,
bending or twisting forces that a surgeon may apply to the lead
during open procedure placement. The flexibility of the ribbon
structure 506, however, is such that the ribbon structure retains
the non-planar configuration upon removal of the force. In other
words, the ribbon structure is floppy and flexible so that once it
is placed by a surgeon via bending, twisting, weaving, etc., the
ribbon structure conforms to the anatomy and remains conformed
after the surgeon finally places the lead and is no longer applying
an type of force to it.
[0091] With reference to FIG. 5G, the ribbon structure 506 is
configured to assume and retain an undulated configuration along
its longitudinal axis. In other words, the ribbon structure 506 is
configured to bend in response to the application of a bending
force, in at least one curve, or a series of successive curves in
alternating directions along a longitudinal axis 519 extending down
the center of the ribbon structure. In the example state shown in
FIG. 5G, the ribbon structure 506 assumes sharper curves in the
electrode-free regions. i.e., areas of insulative material 518a-c,
518d-f, relative to slight curves assumed in the electrode cluster
516a-d, 516e-h regions.
[0092] With reference to FIG. 5H, the ribbon structure 506 is also
configured to assume and retain an undulated configuration in
regions of insulative material 530 between adjacent electrodes 508,
512. In the example shown in FIG. 5H, the ribbon structure 506 is
configured so that the electrodes 508, 512 are evenly distributed
along the length of the ribbon structure. Thus, unlike the example
shown in FIG. 5G, there are no large areas of insulative material
518a-c, 518d-f between adjacent electrode clusters 516a-d, 516e-h,
and the ribbon structure 506 assumes tighter curves, e.g. lower
radius of curvature, than the curves of FIG. 5G. In one
configuration, the ribbon structure 506 assumes curves having a
radius of curvature 531 in the range of 1 mm and 3 mm. Note that,
while it is possible for a ribbon structure to curve at every
spacing between adjacent electrodes, for ease of illustration, the
ribbon structure 506 shown in FIG. 5H curves at every other
occurrence of a spacing between adjacent electrodes.
[0093] With reference to FIG. 5I, the ribbon structure 506 is
configured to assume and retain a twisted configuration about its
longitudinal axis. In other words, the ribbon structure 506 is also
configured such that opposed edges 521a, 521b of the ribbon
structure curve in response to the application of a twisting force,
about a longitudinal axis 523 extending down the center of the
ribbon structure.
[0094] Regarding traditional percutaneous leads, while these leads
may be more flexible than known paddle leads, percutaneous leads by
design have a linear array of ring electrodes and possibly a tip
electrode. These leads do not have a two-dimensional array of
electrodes that enable high resolution targeting of multiple nerve
structures by electrode shifting
[0095] Therapy Module
[0096] With reference to FIGS. 6A, 6B, 6C, and 6D, the therapy
module 214 of an implantable neuromodulation device 206 includes a
housing 602 that encloses various electronic components. The
housing 602 may be formed of biocompatible metal, such as titanium
and has a form factor that includes one or more features configured
to mate with a corresponding feature of a screw-head 314 of a
pedicle screw 208a. In some configuration, one or more portions of
the housing may be formed of or coated with a layer of a pliable,
biocompatible material, such as a low durometer rubber or
rubber-like material, e.g., silicone. Alternatively, the housing
may be formed of a combination of biocompatible, non-metal
materials including for example, a majority of housing may be
formed of a polymer thermoplastic such as poly-ether-ether-ketone
(PEEK), with certain features being coated with or formed of
pliable silicone. The respective features mate in a manner that
enables the therapy module 214 to mechanically couple to and
subsequently decouple from the screw-head 314. The coupling and
decoupling between the therapy module 214 and the screw-head 314 is
such that the decoupling of one component from another does not
alter or damage the structural integrity of either component. In
this sense, the components may be described as being removably
coupled to each other, where decoupling involves the application of
minimal force.
[0097] With reference to FIGS. 6A and 6B, the mating feature of the
housing 602 may be a center projection 604 having an outer wall
606, and the corresponding mating feature of the screw-head 314 is
a screw-head cavity 608. The screw-head cavity 608 is defined by
the space between opposed sides 610 of the screw-head 314. The
lower portion of the screw-head cavity 608 is configured to receive
a rod 210a of a rod-and-screw stabilization device and a threaded
insert 612. The threaded insert 612 engages threads formed in the
inner walls of the opposed sides 610 of the screw-head 314 and
advances downward toward the rod 201a during rotation to engage a
portion of the rod and secure it in place.
[0098] In the therapy module 214 configuration shown in FIG. 6A,
the outer wall 606 of the center projection 604 is threaded and
like the thread insert 612, it too engages the threads formed in
the inner walls of the opposed sides 610 of the screw-head 314 and
advances downward toward the threaded insert 612 during rotation
until the top surface 614 of the screw-head 314 is in abutting
contact with an under surface 616 of the housing 602. Thus, in this
configuration the therapy module 214 is coupled to the screw-head
314 by threaded rotation and may be subsequently decoupled by
threaded rotation without altering or damaging the structural
integrity of either the therapy module 214 or the screw-head
314.
[0099] In the therapy module 214 configuration shown in FIG. 6B,
the center projection 604 of the housing 602 is sized such that the
center projection tightly fits into the screw-head cavity 608. As
such, the outer wall 606 of the projection engages the inner walls
of the opposed sides 610 of the screw-head 314 to establish a tight
friction fit that secures the housing 602 to the screw-head 314. To
facilitate this friction fit, the center projection may be formed
of or coated with a pliable material, e.g., a plastic, that
compress upon force to tightly fits into the screw-head cavity 608.
The housing 602 may be pushed downward toward the threaded insert
612 until the top surface 614 of the screw-head 314 is in abutting
contact with an under surface 616 of the housing 602. Thus, in this
configuration the therapy module 214 is coupled to the screw-head
314 by a push force and may be subsequently decoupled by a pull
force without altering or damaging the structural integrity of
either the therapy module 214 or the screw-head 314.
[0100] With reference to FIG. 6C, the mating feature of the housing
602 may be a pair of opposed side projections 618a, 618b that
define a housing cavity 620, and the corresponding mating feature
of the screw-head 314 is a portion of the screw-head itself. The
housing cavity 620 is defined by the space between opposed side
projections 618a, 618b of the housing 602, and is configured to
receive the portion of the screw-head 314. In this configuration,
the screw-head 314 also has a screw-head cavity 608 configured to
receive a rod 210a of a rod-and-screw stabilization device and a
threaded insert 612 to engage a portion of the rod and secure it in
place.
[0101] In one configuration, the inner walls of the opposed side
projections 618a, 618b are threaded and engage with corresponding
threads formed in the outer wall of the screw-head 314. Thus, in
this configuration the therapy module 214 is coupled to the
screw--head 314 by threaded rotation and may be subsequently
decoupled by threaded rotation without altering or damaging the
structural integrity of either the therapy module 214 or the
screw-head 314.
[0102] In another configuration, the housing cavity 620 of the
housing 602 is sized such it tightly fits over the screw-head 314.
As such, the inner walls of the opposed side projections 618a, 618b
engage the outer wall of the screw-head 314 to establish a tight
friction fit that secures the housing 602 to the screw-head 314. To
facilitate this friction fit, the inner walls of the opposed side
projections 618a, 618b may be coated with a pliable material, e.g.,
a plastic, that compresses upon force to tightly fit over the
screw-head 314. The housing 602 may be pushed downward over the
screw-head 314 until the top surface 614 of the screw-head 314 is
in abutting contact with an under surface 616 of the housing 602.
Thus, in this configuration the therapy module 214 is coupled to
the screw-head 314 by a push force and may be subsequently
decoupled by a pull force without altering or damaging the
structural integrity of either the therapy module 214 or the
screw-head 314.
[0103] Continuing with FIG. 6A, the therapy module 214 includes a
therapy-module interface structure 218 configured to couple with a
lead interface structure. In one configuration, the therapy-module
interface structure 218 is a dongle 622 having an in-line connector
structure 624 configured to mate with a corresponding connector
structure of the lead interface structure. In another
configuration, the dongle 622 has four in-line connector structures
626.
[0104] With reference to FIG. 6D, the electronic components 630 of
the therapy module 214 are mostly located in a upper region 628 of
the housing 602. Some electronic components, however, may be
located in other portions of the housing. For example, the energy
source 632, e.g., battery or inductively charged capacitors, may be
located inside of the projection 604. The battery may be a wireless
rechargeable or non-rechargeable (i.e., primary cell). The battery
may be an ultra thin film battery, or single layer carbon fiber
battery. The battery could be in the shape of a button cap. Further
description of the electronic components 630 of the therapy module
214 are provided below with reference to FIGS. 9-12.
[0105] With reference to FIG. 7, in an alternate embodiment of a
therapy module 214 configured for use with a pedicle screw 708a
having a larger screw-head cavity 720, most of the electronic
components 730 are located in a portion of the housing 702 that
lies within the screw-head cavity 720 just above the threaded
insert 712. The therapy module 214 may be coupled and decoupled
from the screw-head 714 in anyone of the ways described above with
reference to FIGS. 6A, 6B and 6C. The form factor of the housing
702 includes a domed top 722 that projects above the top of the
screw-head 714. The domed top 722 may be formed of or coated with a
layer of pliable material that includes a groove 724. The groove
724 is configured to receive and secure in place, a portion of a
dongle wire 726 that extends from the housing 702.
[0106] With reference to FIG. 8, in another alternate embodiment of
a therapy module 214 configured for use with a pedicle screw 808a
similar to the pedicle screw of FIG. 7, most of the electronic
components 830 are located in a portion of the housing 802 that
lies within the screw-head cavity 820 just above the threaded
insert 812. The therapy module 214 may be coupled and decoupled
from the screw-head 814 in anyone of the ways described above with
reference to FIGS. 6A, 6B and 6C. The therapy module 214 includes
an interface structure 822 comprising a plurality of electrical
connectors exposed at the upper region of the housing 802. The
electrical connectors are configured to mate with a corresponding
plurality of electrical connectors of a lead interface structure
824.
[0107] Electronic Components
[0108] With reference to FIG. 9, the neuromodulation device 206
includes a therapy module 214 coupled to a ribbon lead 212 for
delivering therapy to the patient. The neuromodulation device 206
may also include a health information module 940 associated with
one or more implant-integrity sensors 942, 944 and one or more
patient health sensors 946 for collecting and analyzing data, and
indicating the condition of an orthopedic implant device and
patient status. The implant-integrity sensors 942, 944 and patient
health sensors 946 are typically included in the health information
module. Some implant-integrity sensors, however, may be directly
associated with the orthopedic implant device and coupled to the
health information module 940 by a cable.
[0109] An external charger/controller 904 generates and transmits
or emits energy to the therapy module through an inductive coupling
928. The therapy module 214 receives the energy transmitted by the
charger/controller 904, stores the energy, and eventually uses the
energy to generate and deliver a form of therapy to the patient
through the ribbon lead 212. The inductive coupling between the
charger/controller 904 and the therapy module 214 may also
facilitate data communication between these components for the
downloading of programming information from the charger/controller
to the therapy module, and the uploading of operational
information, e.g., therapy delivery records, from the therapy
module to the charger/controller. Alternatively, programming and
data collection between the therapy module 214 and the
charger/controller 904 may be implemented through a wireless RF
telemetry or Bluetooth interface 930. In either of the inductive
coupling or the RF telemetry implementations, health information
collected by the health information module 940 may also be uploaded
to the charger/controller 904 through a communications bus 932 that
interconnects the Therapy module 214 and the health information
module.
[0110] An external patient interface device 906 may upload health
information collected by the health information module 940 through
a wireless RF telemetry or Bluetooth interface 934. Operational
information, e.g., therapy delivery records, may also be uploaded
to the external patient interface device 906 from the therapy
module 214 through the communications bus 932 that interconnects
the therapy module and the health information module 940. The
external patient interface device 906 may also provide for limited
operation control of the therapy module 214. To this end, the
external patient interface device 906 may contain applications or
software that would interact with the patient to assess his pain
and adjust the stimulation parameters. The parameters could be
adjusted manually by the patient, automatically by the therapy
module in conjunction with the application algorithm, or remotely
by the clinician. Command signals may be sent from the patient
interface device to the therapy module 214 over the RF telemetry
interface 934 and through the communication bus 932 to initiate the
delivery of a therapy by the therapy module, or to program the
therapy module to deliver a therapy in accordance with a therapy
regimen.
[0111] FIG. 10 is a block diagram of the therapy module 214 and the
ribbon lead 212 of FIG. 9. The therapy module 214 includes a
therapy-module interface structure 218 adapted to interface with a
corresponding lead interface structure 216 of the lead. The ribbon
lead includes multiplexer circuitry for selecting one or more
electrode cluster 516a-d, 516e-h to electrically interface with the
electrode interface 1008. The electrode interface 1008, in turn,
includes multiplexer circuitry for selecting one or more electrodes
within the selected cluster as needed for delivery of a therapy.
The electrode interface 1008 may also include circuitry that
provides other features, or capabilities, including but not limited
to isolation, and charge-balancing functions, that are required for
a proper interface with neurological tissue.
[0112] The charging circuitry 1014 receives energy from the
charger/controller 904 over the inductive coupling interface 928
and provides the energy to an energy storage component 1024 of the
therapy module. The energy storage component 1024 may be a
supercapacitor or one or more rechargeable batteries. In another
configuration, energy may be provided by a remote inductive energy
source and used in real time, in which case energy is note stores
and the energy storage component 1024 may not be necessary.
[0113] A therapy controller 1010 is coupled to the electrode
interface 1008 and controls the selection of electrodes by the
electrode interface through control signals 1012. Electrode
selection by the therapy controller 1010 may result in delivery of
a therapy through a pair of electrodes in an electrode cluster
516a-e, 516e-h, e.g., a bipolar electrode configuration. The
therapy module 214 also provides the signal needed to deliver
electrical stimulation energy through the selected electrodes. The
therapy controller 1010 is coupled to the energy storage component
1024 and configured to draw energy from the energy storage
component and generate the stimulation energy signal.
[0114] Each electrode cluster 516a-d, 516e-h of the ribbon lead 212
may also include a temperature sensor configured to a provide
signal indicative of the temperature at that cluster. The
temperature sensors are coupled to the electrode interface 1008
through the lead interface structure 216 and therapy module
interface structure 218. In one configuration, the temperature
sensors provide a temperature feedback signal 1018 to the therapy
controller 1010 to ensure that the temperature at the target area
meets a specified criterion. Temperature feedback may also provide
an indication of successful therapy settings. Related to heat as an
alternate modality, the stimulation could also be used to generate
a certain amount of non-damaging heat in the area that could be
synergistically therapeutic.
[0115] In addition to supplying energy for the generation of
therapy signals, the energy storage component 1024 supplies the
voltages and currents necessary for operation of electronic
components of the therapy module 214, including for example,
components of the electrode interface 1008, the therapy controller
1010, and the charging circuitry 1014. The therapy module 214 also
includes a memory circuit 1026. The memory circuit 1026 may store
information corresponding to a history of delivered therapies,
energy storage component recharge sessions, and temperature
measurements.
[0116] The therapy module 214 may include a communications
interface 1022 that enables RF telemetry communication between the
therapy module and the charger/controller 904 through a wireless
communication link. The charger/controller 904 allows a physician
to program the therapy controller 1010 with a therapy regimen. For
example, the therapy controller 1010 may be programmed to deliver
periodic doses of a selected therapy during a treatment session.
The communications interface 1022 also allows for the downloading
of information from the memory circuit 1026.
[0117] FIG. 11 is a block diagram of the health information module
140 and various sensors 1114, 1116, 1118, 1120, 1122 that may
function as one or both of an implant-integrity sensor and patient
health sensors. The sensors include one or more strain gauges 1114,
piezoelectric sensors 1116, position sensors/GPS 1118, each located
remote from the health information module 140 and one or more
accelerometers 1120 and gyroscopes 1122, each located within the
information module. Sensors remote from the health information
module 140 connect to a cable connector 158 or header of the module
by cables. The cable connector 158 physically secures the cables to
the health information module 140 and physically and electrically
couples each sensor to a sensor data processor 1102 within the
health information module 140.
[0118] The sensor data processor 1102 may obtain and process
signals from the sensors 1114, 1116, 1118, 1120, 1122 to determine
metrics indicative of the mechanical integrity of the implant
device and/or patient heath. Alternatively, or in addition to, the
external patient interface device 116 may obtain information from
the health information module 140 and process the information to
determine metrics. Several device-integrity metrics and
patient-health metrics are envisioned, and the system 110 may be
configured to determine one or more of these metrics.
[0119] A first device-integrity metric, referred to as a
"load-bearing" metric, provides an indication of the load
distribution among different hardware components of an orthopedic
implant device. Most implant devices are configured so that after
implant and after sufficient healing, the weight or force of the
bone structure (herein referred to as "the load" of the bone
structure) being applied to the implant device is distributed among
hardware components of the device so that sonic components bear
more of the load than other components. For example, in
rod-and-screw spinal fixation device, the pedicle screws implanted
in bone are intended to carry more load than the rod. A load
distribution among hardware components that does not compart with
the intended distribution may indicate that healing is not complete
or that the implant device is not stable relative to the bone.
Continuing with the rod-and-screw spinal fixation device, the
device may become unstable or loose clue to insufficient regrowth
or fusion of honey material surrounding the pedicle screws. In this
case, sonic of the load that would otherwise be carried by the
pedicle screws would be redistributed to the rod.
[0120] A lead-bearing metric may be obtained, for example, through
a strain gauge 1114 or piezoelectric sensor 1116 associated with a
hardware component of the orthopedic implant device. The output of
either of these sensors 1114, 1116 may serve as a measure of load
carried by the component to which it is attached. Monitoring the
output overtime allows for detection of changes in load that, may
correlate to reduced device integrity. For example, an increase in
strain gauge 1114 output from a component that is not intended to
carry as much load as another component indicates that the other
component is loose. Again, continuing with the rod-and-screw spinal
fixation device, an increase in output of a strain gauge 1114
attached to the rod indicates that the pedicle screws are
loose.
[0121] A second device-integrity metric, referred to as a
"relative-position" metric provides an indication of the relative
positions of different hardware components of an orthopedic implant
device. Most implant devices are configured so that after implant
and after sufficient healing, the positions of different hardware
components of the device relative to each other fixed. For example,
in a rod-and-screw spinal fixation device, the relative positions
of pedicle screws and the rod should be fixed. A relative position
finding or metric among hardware components that does not compart
with a fixed positioning may indicate that one or both of the
hardware components is not stable. Continuing with the
rod-and-screw spinal fixation device, the device may become
unstable or loose due to insufficient regrowth or fusion of honey
material surrounding the pedicle screws. In this case, the relative
position between the pedicle screws and rod would change from a
baseline value.
[0122] A relative position metric may be obtained, for example,
through position sensors 1118, such as GPS sensors, that are
associated with hardware components of the orthopedic implant
device. The output of the position sensors 1118 may serve as a
measure of distance between the two components. Monitoring the
output overtime allows for detection of changes in distance that
may correlate to reduced device integrity. For example, an increase
in distance indicates that the hardware components have moved
relative to each other. Again, continuing with the rod-and-screw
spinal fixation device, an increase in the distance between the rod
and either of the pedicle screws indicates that one of the hardware
components has moved and may be loose.
[0123] A third device-integrity metric, referred to as a
"stability" metric, provides an indication of the stability of one
or more hardware components of an orthopedic implant device.
Implant devices are configured so that after implant and after
sufficient healing, the different hardware components of the device
are fixed in place. For example, in the rod-and-screw spinal
fixation device, the pedicle screws and the rod should be fixed. A
stability metric for a hardware component that does not comport
with that of stable and fixed position may indicate that, one or
both of the hardware components is loose. Continuing with the
rod-and-screw spinal fixation device, the device may become
unstable or loose due to insufficient regrowth or fusion of honey
material surrounding the pedicle screws.
[0124] A stability metric may be obtained, for example, through an
accelerometer 1120 within the health information module 140. The
accelerometer 1120 senses motion and vibration and outputs signals
representing such movements. Some movements may be due to patient
activity, while other movements may be due to movement of a
hardware component. For example, a loose pedicle screw may lead to
vibration of the rod which in turn would result in vibration of the
health information module 140 secured to the rod. The sensor data
processor 1102 within the health information module 140 may process
the signals to distinguish between movement due to the patient from
movement due to the implant device. This may be done through
filtering and spectral analysis of the accelerometer signal,
wherein movement resulting from vibration of the rod is at a
different spectral frequency component that that caused by patient
movement.
[0125] A first patient-heath metric, referred to herein as an
"activity" metric provides an indication of the movement of the
patient. An activity metric may be obtained, for example, through
the accelerometer 1120 in the health information module 140. As
just noted, the accelerometer 1120 senses motion and vibration and
outputs signals representing such movements. Some movements may be
due to patient activity, while other movements may be due to
movement of a hardware component. The sensor data processor 1102
within the health information module 140 may process the signals to
distinguish between movement due to the patient from movement due
to the implant device. This may be done through filtering and
spectral analysis of the accelerometer signal, wherein movement
resulting from vibration of the rod is at a different spectral
frequency component that that caused by patient movement. Potential
biomarkers for pain and or successful relief of pain may be
indicated by patient movement, posture, exercise/activity and
amount of movement in the environment (i.e. going out/travel).
[0126] A second patient-heath metric, referred to herein as a
"motion" metric provides an indication of the range of motion of
the patient. For example, this metric may indicate a patient's
ability to bend over, or turn in a certain direction. A motion
metric may be obtained, for example, through a gyroscope 1122 in
the health information module 140.
[0127] In addition to the various sensors, the health information
module 140 includes a power source 1104, a memory circuit 1106 and
a communication interface 1108. The power source 1104 supplies the
voltages and currents necessary for operation of electronic
components of the module, including for example, components of the
sensor data processor 1102, the sensors and the communication
interface 1108. The power source 1104 may be configured to be
recharged through an inductive coupling link like the one described
above with reference to the therapy module 114. The memory circuit
1106 may store information corresponding to a history of sensor
outputs and metrics determined by the sensor data processor
1102.
[0128] The communications interface 1108 enables RF telemetry
communication between the health information module and the
external patient interface device 116 through a wireless
communication link. The external patient interface device 116
allows for the downloading of information from the memory circuit
1106. Information may also be downloaded from the memory circuit
1106 through the inductive coupling link by inductive telemetry
when the interface is not being used for charging purposes.
[0129] The various aspects of this disclosure are provided to
enable one of ordinary skill in the art to practice the present
invention. Various modifications to exemplary embodiments presented
throughout this disclosure will be readily apparent to those
skilled in the art. Thus, the claims are not intended to be limited
to the various aspects of this disclosure, but are to be accorded
the full scope consistent with the language of the claims. All
structural and functional equivalents to the various components of
the exemplary embodiments described throughout this disclosure that
are known or later come to be known to those of ordinary skill in
the art are expressly incorporated herein by reference and are
intended to be encompassed by the claims. Moreover, nothing
disclosed herein is intended to he dedicated to the public
regardless of whether such disclosure is explicitly recited in the
claims. No claim element is to be construed under the provisions of
35 U.S.C. .sctn. 112, sixth paragraph, unless the element is
expressly recited using the phrase "means for" or, in the case of a
method claim, the element is recited using the phrase "step
for."
* * * * *