U.S. patent application number 12/765685 was filed with the patent office on 2010-10-28 for spinal cord modulation for inducing paresthetic and anesthetic effects, and associated systems and methods.
Invention is credited to Konstantinos Alataris, Jon Parker, Andre B. Walker.
Application Number | 20100274312 12/765685 |
Document ID | / |
Family ID | 42992797 |
Filed Date | 2010-10-28 |
United States Patent
Application |
20100274312 |
Kind Code |
A1 |
Alataris; Konstantinos ; et
al. |
October 28, 2010 |
SPINAL CORD MODULATION FOR INDUCING PARESTHETIC AND ANESTHETIC
EFFECTS, AND ASSOCIATED SYSTEMS AND METHODS
Abstract
Spinal cord modulation for inducing paresthetic and anesthetic
effects, and associated systems and methods are disclosed. A
representative method in accordance with an embodiment of the
disclosure includes creating a therapeutic effect and a sensation
in a patient by delivering to the patient first pulses having a
first set of first signal delivery parameters and second pulses
having a second set of second signal delivery parameters, wherein a
first value of at least one first parameter of the first set is
different than a second value of a corresponding second parameter
of the second set, and wherein the first pulses, the second pulses
or both the first and second pulses are delivered to the patient's
spinal cord.
Inventors: |
Alataris; Konstantinos;
(Belmont, CA) ; Walker; Andre B.; (Monte Sereno,
CA) ; Parker; Jon; (San Jose, CA) |
Correspondence
Address: |
PERKINS COIE LLP;PATENT-SEA
P.O. BOX 1247
SEATTLE
WA
98111-1247
US
|
Family ID: |
42992797 |
Appl. No.: |
12/765685 |
Filed: |
April 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61171790 |
Apr 22, 2009 |
|
|
|
Current U.S.
Class: |
607/46 ;
607/72 |
Current CPC
Class: |
A61N 1/36021 20130101;
A61N 1/36071 20130101; A61N 1/06 20130101; A61N 1/36171 20130101;
A61N 1/36178 20130101; A61N 1/3615 20130101; A61N 1/36132
20130101 |
Class at
Publication: |
607/46 ;
607/72 |
International
Class: |
A61N 1/34 20060101
A61N001/34; A61N 1/36 20060101 A61N001/36 |
Claims
1. A method for treating a patient, comprising: creating a
therapeutic effect and a sensation in a patient by delivering to
the patient first pulses having a first set of first signal
delivery parameters and second pulses having a second set of second
signal delivery parameters, wherein a first value of at least one
first parameter of the first set is different than a second value
of a corresponding second parameter of the second set, and wherein
the first pulses, the second pulses or both the first and second
pulses are delivered to the patient's spinal cord.
2. The method of claim 1 wherein delivering the first pulses
includes delivering bursts of first pulses, and wherein delivering
the second pulses includes delivering a single second pulse during
an interval between sequential bursts of the first pulses, without
the first pulses overlapping temporally with the second pulses,
wherein the first pulses have a first pulse width and the second
pulses have a second pulse width greater than the first pulse
width.
3. The method of claim 1 wherein delivering the first and second
pulses includes delivering the first and second pulses to the same
electrode implanted in electrical communication with a target
neural population at the patient's spinal cord, and wherein
delivering the first pulses includes delivering intermittent bursts
of first pulses, and wherein delivering the second pulses includes
delivering a single second pulse during an interval between
sequential bursts of the first pulses, without the first pulses
overlapping temporally with the second pulses, wherein the first
pulses have a first pulse width and the second pulses have a second
pulse width greater than the first pulse width.
4. The method of claim 1 wherein delivering the first pulses
includes delivering bursts of first pulses, and wherein delivering
the second pulses includes delivering a burst of second pulses
during an interval between sequential bursts of the first pulses,
without the first pulses overlapping temporally with the second
pulses, wherein the first pulses have a first pulse width and the
second pulses have a second pulse width greater than the first
pulse width.
5. The method of claim 1 wherein the first parameter is a first
signal frequency and the second parameter is a second signal
frequency and wherein the first signal frequency is higher than the
second signal frequency.
6. The method of claim 1 wherein the first parameter is a first
signal frequency and the second parameter is a second signal
frequency and wherein the first signal frequency is in the range of
from about 1.5 kHz to about 50 kHz, and the second signal frequency
is in the range of from about 2 Hz to about 1.2 kHz.
7. The method of claim 1 wherein creating a therapeutic effect
includes creating an anesthetic, non-paresthetic effect, and
wherein creating a sensation includes creating a paresthetic
effect.
8. A method for treating a patient, comprising: creating a
therapeutic, non-paresthetic effect in a patient by delivering, to
a target neural population at the patient's spinal cord, first
pulses having a first set of first signal delivery parameters; and
creating a sensation in the patient by delivering, to the spinal
cord, second pulses having a second set of second signal delivery
parameters, wherein a first value of at least one first parameter
of the first set is different than a second value of a
corresponding second parameter of the second set.
9. The method of claim 8 wherein creating a therapeutic effect
includes creating an anesthetic effect.
10. The method of claim 8 wherein creating a sensation includes
creating a paresthetic effect.
11. The method of claim 8 wherein delivering the second pulses
includes delivering the second pulses to the target neural
population.
12. The method of claim 8 wherein delivering the first pulses
includes delivering bursts of first pulses, and wherein delivering
the second pulses includes delivering a single second pulse during
an interval between sequential bursts of the first pulses, without
the first pulses overlapping temporally with the second pulses,
wherein the first pulses have a first pulse width and the second
pulses have a second pulse width greater than the first pulse
width.
13. The method of claim 8 wherein delivering the first and second
pulses includes delivering the first and second pulses to the same
electrode implanted in electrical communication with the target
neural population, and wherein delivering the first pulses includes
delivering intermittent bursts of first pulses, and wherein
delivering the second pulses includes delivering a single second
pulse during an interval between sequential bursts of the first
pulses, without the first pulses overlapping temporally with the
second pulses, wherein the first pulses have a first pulse width
and the second pulses have a second pulse width greater than the
first pulse width.
14. The method of claim 8 wherein delivering the first pulses
includes delivering bursts of first pulses, and wherein delivering
the second pulses includes delivering a burst of second pulses
during an interval between sequential bursts of the first pulses,
without the first pulses overlapping temporally with the second
pulses, wherein the first pulses have a first pulse width and the
second pulses have a second pulse width greater than the first
pulse width.
15. The method of claim 8 wherein the first parameter is a first
signal frequency and the second parameter is a second signal
frequency and wherein the first signal frequency is higher than the
second signal frequency.
16. The method of claim 8 wherein the first parameter is a first
signal frequency and the second parameter is a second signal
frequency and wherein the first signal frequency is in the range of
from about 1.5 kHz to about 50 kHz, and the second signal frequency
is in the range of from about 2 Hz to about 1.2 kHz.
17. The method of claim 8 wherein the first parameter is a first
pulse width and the second parameter is a second pulse width and
wherein the first pulse width is less than the second pulse
width.
18. The method of claim 8, further comprising: fixing an amplitude
of the first pulses and preventing the patient from changing the
amplitude of the first pulses; and allowing the patient to change
an amplitude of the second pulses.
19. The method of claim 8, further comprising: increasing an
amplitude of the first pulses without creating a patient-detectable
sensation; creating a patient sensation by increasing an amplitude
of the second pulses as the amplitude of the first pulses is
increased; and based on patient feedback to the second pulses,
changing the first signal delivery parameters.
20. A method for treating a patient, comprising: creating an
anesthetic, non-paresthetic effect in a patient by delivering, to a
target neural population at the patient's spinal cord, first pulses
having a first set of first signal delivery parameters, wherein the
anesthetic effect of the first pulses is undetected by the patient
and/or produces a reduction or elimination of pain in the patient;
creating a patient-detectable paresthetic effect in the patient
concurrent with the anesthetic, non-paresthetic effect by
delivering, to the patient's spinal cord, second pulses having a
second set of second signal delivery parameters, wherein a first
value of at least one first parameter of the first set is different
than a second value of a corresponding second parameter of the
second set; and based on patient feedback to the second pulses,
changing the first signal delivery parameters.
21. The method of claim 20 wherein creating a patient-detectable
paresthetic effect includes creating a patient-detectable
paresthetic effect with an external trial modulator placed external
to the patient, and wherein the method further comprises:
implanting a modulator in the patient; and programming the
implanted modulator to create an anesthetic, non-paresthetic effect
in the patient by delivering the first pulses in accordance with
the changed first signal delivery parameters.
22. The method of claim 20 wherein delivering the second pulses
includes delivering the second pulses to the same target neural
population as receives the first pulses.
23. The method of claim 20 wherein the target neural population is
a first target neural population and wherein delivering the second
pulses includes delivering the second pulses to a second target
neural population different than the first target neural
population.
24. The method of claim 20 wherein changing the first signal
delivery parameters includes changing an amplitude of the first
pulses.
25. The method of claim 20 wherein changing the first signal
delivery parameters includes changing a position of an electrode
delivering the first pulses.
26. The method of claim 20 wherein delivering first pulses includes
delivering first pulses from a first electrode of an implanted
electrode device, and wherein changing the first signal delivery
parameters includes delivering the first pulses from a second
electrode spaced apart from the first electrode.
27. The method of claim 20, further comprising identifying the
patient as one who receives the anesthetic, non-paresthetic effect
when in at least one body position, but not when in at least
another body position.
28. The method of claim 20, further comprising obtaining patient
feedback as a result of changing strengths of the first and second
pulses in a parallel manner.
29. A method for treating a patient, comprising: creating an
anesthetic, non-paresthetic effect in a patient by delivering, to a
target neural population at the patient's spinal cord, first pulses
having a first set of first signal delivery parameters, wherein the
anesthetic effect of the first pulses is undetected by the patient
and/or produces a reduction or elimination of pain in the patient;
providing an indication of a strength of the first pulses by
creating a patient-detectable paresthetic effect in the patient,
wherein creating the paresthetic effect includes delivering, to the
patient's spinal cord, second pulses having a second set of second
signal delivery parameters, and wherein a strength of the second
pulses is correlated with a strength of the first pulses, and
wherein a first value of at least one first parameter of the first
set is different than a second value of a corresponding second
parameter of the second set; and changing the strengths of the
first and second pulses in a parallel manner.
30. The method of claim 29 wherein changing the strengths of the
pulses includes changing the amplitudes of the pulses.
31. The method of claim 29 wherein changing the strengths of the
first and second pulses in a parallel manner includes (a)
increasing the strengths concurrently, (b) decreasing the strengths
concurrently, or both (a) and (b).
32. The method of claim 29 wherein changing the strengths of the
pulses includes changing the strengths of the first and second
pulses by the same amount.
33. The method of claim 29 wherein the strengths of the pulses are
offset, and wherein changing the strengths of the pulses includes
changing the strengths of the pulses by different amounts.
34. The method of claim 29 wherein delivering the first and second
pulses includes delivering the first and second pulses to the same
target neural population.
35. The method of claim 29 wherein changing the strengths of the
first and second pulses includes increasing the strength of the
second signal as the strength of the first signal increases, in a
concurrent or sequential manner.
36. The method of claim 29 wherein changing the strengths of the
pulses includes changing the strengths of the pulses in response to
a patient request.
37. A method for treating a patient, comprising: creating an
anesthetic, non-paresthetic effect in a patient by delivering, to a
target neural population at the patient's spinal cord, first pulses
having a first set of first signal delivery parameters, wherein the
anesthetic effect of the first pulses is undetected by the patient
and/or produces a reduction or elimination of pain in the patient;
creating a patient-detectable paresthetic effect in the patient by
delivering, to the patient's spinal cord, second pulses having a
second set of second signal delivery parameters, wherein a first
value of at least one first parameter of the first set is different
than a second value of a corresponding second parameter of the
second set; changing amplitudes of the first and second pulses in
parallel; and identifying a fault with the delivery of the first
pulses based in least in part on the presence or absence of patient
response to the changing amplitude of the second pulses.
38. The method of claim 37 wherein changing the amplitudes of the
first and second signals includes changing the amplitudes
concurrently.
39. The method of claim 37 wherein identifying a fault is based at
least in part on an absence of a patient response.
40. The method of claim 37 wherein identifying a fault is based at
least in part on the presence of a patient response.
41. The method of claim 37 wherein changing amplitudes includes
increasing amplitudes.
42. The method of claim 37 wherein changing amplitudes includes
decreasing amplitudes.
43. The method of claim 37 wherein identifying a fault includes
identifying an electrical discontinuity in an electrical path
between a pulse generator and a signal delivery electrode.
44. The method of claim 37 wherein identifying a fault includes
identifying a signal delivery system as being in an off state.
45. A method for treating a patient, comprising: creating an
anesthetic, non-paresthetic effect in a patient by delivering, to a
target neural population at the patient's spinal cord, first pulses
having a first set of first signal delivery parameters; and based
on a request from the patient, supplementing the anesthetic,
non-paresthetic effect in the patient with a patient-detectable
paresthetic effect by delivering, to the patient's spinal cord,
second pulses having a second set of second signal delivery
parameters, wherein a first value of at least one first parameter
of the first set is different than a second value of a
corresponding second parameter of the second set.
46. The method of claim 45 wherein the patient previously received
paresthesia-inducing pulses from a first implanted spinal cord
modulator, and wherein delivering the first pulses includes
delivering the first pulses from a second implanted spinal cord
modulator, and wherein supplementing the anesthetic,
non-paresthetic effect in the patient with a patient-detectable
paresthetic effect includes emulating an effect of the
paresthesia-inducing pulses by delivering the second pulses from
the second implanted spinal cord modulator.
47. The method of claim 45, further comprising: fixing an amplitude
of the first pulses and preventing the patient from changing the
amplitude of the first pulses; and allowing the patient to change
an amplitude of the second pulses.
48. The method of claim 45 wherein providing the first and second
pulses includes providing the first and second pulses to the same
target neural population.
49. The method of claim 45 wherein providing the first and second
pulses includes providing the first and second pulses to different
target neural populations.
50. A method for treating a patient, comprising: in a patient who
previously received paresthesia-inducing pulses from a first
implanted spinal cord modulator, implanting a second spinal cord
modulator; and using the second spinal cord modulator to: create an
anesthetic, non-paresthetic effect in the patient by delivering
first pulses having a first set of first signal delivery parameters
to a target neural population at the patient's spinal cord; and
create a patient-detectable paresthetic effect in the patient by
delivering, to the patient's spinal cord, second pulses having a
second set of second signal delivery parameters, wherein a first
value of at least one first parameter of the first set is different
than a second value of a corresponding second parameter of the
second set, and wherein the paresthetic effect emulates the
paresthesia-inducing pulses from the first implanted spinal cord
modulator.
51. The method of claim 50, further comprising removing the first
implanted spinal cord modulator from the patient and replacing the
first implanted spinal cord modulator with the second spinal cord
modulator.
52. The method of claim 50, further comprising: fixing an amplitude
of the first pulses and preventing the patient from changing the
amplitude of the first pulses; and allowing the patient to change
an amplitude of the second pulses.
53. A patient treatment system, comprising: a signal delivery
device having a plurality of electrodes configured to be implanted
within a patient, proximate to one or more target neural
populations at the patient's spinal cord; an implantable pulse
generator having a controller programmed with instructions for:
directing first pulses to the signal delivery device to create an
anesthetic, non-paresthetic effect in the patient, the first pulses
having a first set of first signal delivery parameters; and
directing second pulses to the signal delivery device to create a
paresthetic effect in the patient, the second pulses having a
second set of second signal delivery parameters, wherein a first
value of at least one first parameter of the first set is different
than a second value of a corresponding second parameter of the
second set.
54. The system of claim 53, further comprising: an external
physician programmer programmed with instructions for adjusting an
amplitude of the first pulses; and an external patient controller
programmed with instructions for adjusting an amplitude of the
second pulses, and programmed with instructions preventing
adjustment of the amplitude of the first pulses.
55. The system of claim 53 wherein the implantable pulse generator
further includes instructions for receiving updates to the first
signal delivery parameters, independent of updates to the second
signal delivery parameters.
56. The system of claim 53 wherein the implantable pulse generator
includes instruction for interleaving one or more second pulses
between sequential bursts of the first pulses.
57. The system of claim 53 wherein the implantable pulse generator
includes instructions for directing the first pulses to a first
electrode of the signal delivery device and directing the second
pulses to a second electrode of the signal delivery device
different that the first electrode.
58. The system of claim 53 wherein the first pulses have a
frequency of from about 3 kHz to about 10 kHz, and the second
pulses have a frequency of from about 20 Hz to about 1.2 kHz.
59. The system of claim 53 wherein the implantable pulse generator
is programmed with instructions for directing the first and second
pulses sequentially to the same electrode of the signal delivery
device.
60. The system of claim 53 wherein the implantable pulse generator
is programmed with instructions for directing the first and second
pulses to the same electrode of the signal delivery device, with a
single second pulse directed during an interval between sequential
bursts of the first pulses, without the first pulses overlapping
temporally with the second pulses, and with the first pulses having
a first pulse width and the second pulses having a second pulse
width less than the first pulse width, the first pulses being
directed at a first frequency, the second pulses being directed at
a second frequency less than the first frequency.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to U.S. Provisional
Application 61/171,790, filed on Apr. 22, 2009 and incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present disclosure is directed generally to spinal cord
modulation for inducing paresthetic and anesthetic effects, and
associated systems and methods.
BACKGROUND
[0003] Neurological stimulators have been developed to treat pain,
movement disorders, functional disorders, spasticity, cancer,
cardiac disorders, and various other medical conditions.
Implantable neurological stimulation systems generally have an
implantable pulse generator and one or more leads that deliver
electrical pulses to neurological tissue or muscle tissue. For
example, several neurological stimulation systems for spinal cord
stimulation (SCS) have cylindrical leads that include a lead body
with a circular cross-sectional shape and one or more conductive
rings spaced apart from each other at the distal end of the lead
body. The conductive rings operate as individual electrodes and, in
many cases, the SCS leads are implanted percutaneously through a
large needle inserted into the epidural space, with or without the
assistance of a stylet.
[0004] Once implanted, the pulse generator applies electrical
pulses to the electrodes, which in turn modify the function of the
patient's nervous system, such as altering the patient's
responsiveness to sensory stimuli and/or altering the patient's
motor-circuit output. In pain treatment, the pulse generator
applies electrical pulses to the electrodes, which in turn can
generate sensations that mask or otherwise alter the patient's
sensation of pain. For example, in many cases, patients report a
tingling or paresthesia that is perceived as more pleasant and/or
less uncomfortable than the underlying pain sensation. While this
may be the case for many patients, many other patients may report
less beneficial effects and/or results. Accordingly, there remains
a need for improved techniques and systems for addressing patient
pain.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a partially schematic illustration of an
implantable spinal cord modulation system positioned at the spine
to deliver therapeutic signals in accordance with an embodiment of
the present disclosure.
[0006] FIG. 2 is a flow diagram illustrating a method for treating
a patient in accordance with a particular embodiment of the
disclosure.
[0007] FIGS. 3A-3F are flow diagrams illustrating further methods
for treating a patient in accordance with further embodiments of
the disclosure.
[0008] FIG. 4 is a schematic illustration of a representative lead
body suitable for providing modulation to a patient in accordance
with several embodiments of the disclosure.
[0009] FIGS. 5A-5D illustrate representative wave forms associated
with signals applied to patients in accordance with particular
embodiments of the disclosure.
[0010] FIG. 6 is a partially schematic, cross-sectional
illustration of a patient's spine, illustrating representative
locations for implanted lead bodies in accordance with embodiments
of the disclosure.
DETAILED DESCRIPTION
[0011] The present disclosure is directed generally to spinal cord
modulation and associated systems and methods that induce, produce,
generate, or otherwise cause paresthetic and anesthetic effects in
a patient. Such systems and methods can be used to treat patient
pain. Specific details of certain embodiments of the disclosure are
described below with reference to methods for modulating one or
more target neural populations or sites of a patient, and
associated implantable structures for providing the modulation.
Although selected embodiments are described below with reference to
modulating the dorsal root and/or other particular regions of the
spinal column to control pain, the leads may be in some instances
be used to modulate other neurological structures of the spinal
cord. Some embodiments can have configurations, components or
procedures different than those described in this section, and
other embodiments may eliminate particular components or
procedures. A person of ordinary skill in the relevant art,
therefore, will understand that the invention may have other
embodiments with additional elements, and/or may have other
embodiments without several of the features shown and described
below with reference to FIGS. 1-6.
[0012] In general terms, aspects of many of the following
embodiments are directed to producing a sensation (e.g.,
paresthesia or a paresthetic effect) in the patient, in addition to
producing a therapeutic effect (e.g., anesthesia or an anesthetic
effect) in the patient. The therapeutic effect can be produced by
inhibiting, suppressing, downregulating, blocking, preventing, or
otherwise modulating the activity of the affected neural population
(e.g., nerve cells). Such embodiments may be useful in cases for
which the patient benefits from an anesthetic effect, but, because
the anesthetic effect typically creates an absence of pain and/or
other sensations, the patient may require the assurance or comfort
of a detectable sensation. By supplementing the anesthetic effect
with a paresthetic effect, which is detected by the patient, the
patient and/or the associated practitioner can better monitor the
manner in which the anesthesia-producing signals are provided. In
other embodiments, the patient and/or the practitioner may have
other bases for supplementing anesthesia-producing signals with
paresthesia-producing signals. Further details are described below
with reference to FIGS. 1-6.
[0013] FIG. 1 schematically illustrates a representative treatment
system 100 for providing relief from chronic pain and/or other
conditions, arranged relative to the general anatomy of a patient's
spinal cord 191. The system 100 can include a pulse generator 101,
which may be implanted subcutaneously within a patient 190 and
coupled to a signal delivery element 110. In a representative
example, the signal delivery element 110 includes a lead or lead
body 111 that carries features for delivering therapy to the
patient 190 after implantation. The pulse generator 101 can be
connected directly to the lead body 111, or it can be coupled to
the lead body 111 via a communication link 102 (e.g., an
extension). Accordingly, the lead 111 can include a terminal
section that is releasably connected to an extension at a break 114
(shown schematically in FIG. 1). This allows a single type of
terminal section to be used with patients of different body types
(e.g., different heights). As used herein, the terms lead and lead
body include any of a number of suitable substrates and/or support
members that carry devices for providing therapy signals to the
patient 190. For example, the lead body 111 can include one or more
electrodes or electrical contacts that direct electrical signals
into the patient's tissue, such as to provide for patient relief.
In other embodiments, the signal delivery element 110 can include
devices other than a lead body (e.g., a paddle) that also direct
electrical signals and/or other types of signals to the patient
190.
[0014] The pulse generator 101 can transmit signals to the signal
delivery element 110 that up-regulate (e.g., stimulate or excite)
and/or down-regulate (e.g., block or suppress) target nerves. As
used herein, and unless otherwise noted, the terms "modulate" and
"modulation" refer generally to signals that have either type of
effect on the target nerves. The pulse generator 101 can include a
machine-readable (e.g., computer-readable) medium containing
instructions for generating and transmitting suitable therapy
signals. The pulse generator 101 and/or other elements of the
system 100 can include one or more processors 107, memories 108
and/or input/output devices. Accordingly, the process of providing
modulation signals (e.g., electrical signals) and executing other
associated functions can be performed by computer-executable
instructions contained on computer-readable media, e.g., at the
processor(s) 107 and/or memory(s) 108. The pulse generator 101 can
include multiple portions, elements, and/or subsystems (e.g., for
directing signals in accordance with multiple signal delivery
parameters), housed in a single housing, as shown in FIG. 1, or in
multiple housings.
[0015] The pulse generator 101 can also receive and respond to an
input signal received from one or more sources. The input signals
can direct or influence the manner in which the therapy
instructions are selected, executed, updated and/or otherwise
performed. The input signal can be received from one or more
sensors 112 (one is shown schematically in FIG. 1 for purposes of
illustration) that are carried by the pulse generator 101 and/or
distributed outside the pulse generator 101 (e.g., at other patient
locations) while still communicating with the pulse generator 101.
The sensors 112 can provide inputs that depend on or reflect
patient state (e.g., patient position, patient posture and/or
patient activity level), and/or inputs that are patient-independent
(e.g., time). In other embodiments, inputs can be provided by the
patient and/or the practitioner, as described in further detail
later. Still further details are included in co-pending U.S.
application Ser. No. 12/703,683, filed on Feb. 10, 2010 and
incorporated herein by reference.
[0016] In some embodiments, the pulse generator 101 can obtain
power to generate the therapy signals from an external power source
103. The external power source 103 can transmit power to the
implanted pulse generator 101 using electromagnetic induction
(e.g., RF signals). For example, the external power source 103 can
include an external coil 104 that communicates with a corresponding
internal coil (not shown) within the implantable pulse generator
101. The external power source 103 can be portable for ease of
use.
[0017] In another embodiment, the pulse generator 101 can obtain
the power to generate therapy signals from an internal power
source, in addition to or in lieu of the external power source 103.
For example, the implanted pulse generator 101 can include a
non-rechargeable battery or a rechargeable battery to provide such
power. When the internal power source includes a rechargeable
battery, the external power source 103 can be used to recharge the
battery. The external power source 103 can in turn be recharged
from a suitable power source (e.g., conventional wall power).
[0018] In some cases, an external programmer 105 (e.g., a trial
modulator) can be coupled to the signal delivery element 110 during
an initial implant procedure, prior to implanting the pulse
generator 101. For example, a practitioner (e.g., a physician
and/or a company representative) can use the external programmer
105 to vary the signal delivery parameters provided to the signal
delivery element 110 in real time, and select optimal or
particularly efficacious parameters. These parameters can include
the position of the signal delivery element 110, as well as the
characteristics of the electrical signals provided to the signal
delivery element 110. In a typical process, the practitioner uses a
cable assembly 120 to temporarily connect the external programmer
105 to the signal delivery device 110. The cable assembly 120 can
accordingly include a first connector 121 that is releasably
connected to the external programmer 105, and a second connector
122 that is releasably connected to the signal delivery element
110. Accordingly, the signal delivery element 110 can include a
connection element that allows it to be connected to a signal
generator either directly (if it is long enough) or indirectly (if
it is not). The practitioner can test the efficacy of the signal
delivery element 110 in an initial position. The practitioner can
then disconnect the cable assembly 120, reposition the signal
delivery element 110, and reapply the electrical modulation. This
process can be performed iteratively until the practitioner obtains
the desired position for the signal delivery device 110.
Optionally, the practitioner may move the partially implanted
signal delivery element 110 without disconnecting the cable
assembly 120. Further details of suitable cable assembly methods
and associated techniques are described in co-pending U.S.
application Ser. No. 12/562,892, filed on Sep. 18, 2009, and
incorporated herein by reference.
[0019] During this process, the practitioner can also vary the
position of the signal delivery element 110. After the position of
the signal delivery element 110 and appropriate signal delivery
parameters are established using the external programmer 105, the
patient 190 can receive therapy via signals generated by the
external programmer 105, generally for a limited period of time. In
a representative application, the patient 190 receives such therapy
for one week. During this time, the patient wears the cable
assembly 120 and the external programmer 105 outside the body.
Assuming the trial therapy is effective or shows the promise of
being effective, the practitioner then replaces the external
programmer 105 with the implanted pulse generator 101, and programs
the pulse generator 101 with parameters selected based on the
experience gained during the trial period. Optionally, the
practitioner can also replace the signal delivery element 110. Once
the implantable pulse generator 101 has been positioned within the
patient 190, the signal delivery parameters provided by the pulse
generator 101 can still be updated remotely via a wireless
physician's programmer (e.g., a physician's remote) 111 and/or a
wireless patient programmer 106 (e.g., a patient remote).
Generally, the patient 190 has control over fewer parameters than
does the practitioner. For example, the capability of the patient
programmer 106 may be limited to starting and/or stopping the pulse
generator 101, and/or adjusting signal amplitude.
[0020] In any of these foregoing embodiments, the parameters in
accordance with which the pulse generator 101 provides signals can
be modulated during portions of the therapy regimen. For example,
the frequency, amplitude, pulse width and/or signal delivery
location can be modulated in accordance with a preset program,
patient and/or physician inputs, and/or in a random or pseudorandom
manner. Such parameter variations can be used to address a number
of potential clinical situations, including changes in the
patient's perception of pain, changes in the preferred target
neural population, and/or patient accommodation or habituation.
[0021] FIG. 2 is a schematic flow diagram illustrating a process
250 for treating a patient in accordance with particular
embodiments of the disclosure. The process 250 can include creating
both a therapeutic effect and a sensation in a patient by
delivering first pulses (e.g., first electrical pulses) having a
first set of signal delivery parameters, and second pulses (e.g.,
second electrical pulses) having a second set of signal delivery
parameters. A first value of at least one parameter of the first
set is different than a second value of a corresponding second
parameter of the second set, and the first pulses, second pulses,
or both are delivered to the patient's spinal cord. In particular
embodiments, the effects on the patient may be separately
attributable to each of the first and second pulses, but in other
embodiments, the effects need not be attributed in such a manner.
In one embodiment, the process 250 can include creating an
anesthetic, non-paresthetic effect in the patient by applying first
pulses to the patient's spinal cord in accordance with first signal
delivery parameters (process portion 251). In general, the
anesthetic, non-paresthetic effect is one that addresses the
patient's pain by blocking or otherwise eliminating the sensation
of pain, without creating a sensation for the patient. In
particular embodiments, the anesthetic, non-paresthetic effect of
the first pulses can have one or both of the following
characteristics. One characteristic is that the anesthetic,
non-paresthetic effect is undetected by the patient. Another
characteristic is that the anesthetic, non-paresthetic effect
produces a reduction or elimination of pain.
[0022] In process portion 252, a paresthetic effect is created in
the patient by applying second pulses to the spinal cord in
accordance with second signal delivery parameters. In general
terms, an aspect of at least one of the second signal delivery
parameters is different than an aspect of the corresponding first
signal delivery parameter, so as to produce a paresthetic effect
rather than an anesthetic, non-paresthetic effect. In particular
embodiments, the paresthetic effect creates a tingling and/or other
patient-detectable sensation. In process portion 253, information
obtained from the patient's feedback to the paresthetic effect is
used. For example, the patient and/or practitioner may use this
information to understand that the system is in an "on" state
rather than an "off" state, and/or to determine whether the lead is
properly or improperly placed, and/or to obtain an indication of
the amplitude or signal strength provided by the system. In other
embodiments, the process can include obtaining different
information and/or taking different actions. Further details of
representative methods employing variations of some or all of the
foregoing steps are described below with reference to FIGS.
3A-3F.
[0023] In some cases, the pain experienced by the patient (and
addressed with the methods and systems of the present disclosure)
may not be experienced by the patient on a continual basis. For
example, in some instances, the patient may experience pain while
standing or walking, but not while lying down. In such instances,
it can be difficult to accurately conduct the pre-implant procedure
described above with reference to FIG. 1. During such a procedure,
the patient is typically lying down in a prone position while the
practitioner adjusts the signal delivery parameters associated with
signals provided by the signal delivery element (e.g., waveform
parameters, active electrodes, and/or the position of the signal
delivery element). FIG. 3A is a schematic flow diagram illustrating
a process 350 that can address the foregoing case. Process 350 can
include creating an anesthetic, non-paresthetic effect in a patient
by delivering, to a target neural population at the patient's
spinal cord, first pulses having a first set of first signal
delivery parameters, with the anesthetic effect of the first pulses
being undetected by the patient. This is an example of the first
characteristic described above with reference to FIG. 2. Because
the anesthetic effect of the first pulses is undetected by the
patient, process 350 can further include creating a
patient-detectable paresthetic effect in the patient, concurrent
with the anesthetic, non-paresthetic effect (process portion 352).
This process can be accomplished by delivering, to the patient's
spinal cord, second pulses having a second set of signal delivery
parameters. A first value of at least one first parameter of the
first set of signal delivery parameters is different than a second
value of a corresponding second parameter of the second set, e.g.,
to produce the paresthetic effect. In this process, the
corresponding parameters of the first and second sets are
analogous. For example, if the frequency of the second pulses is
different than the frequency of the first pulses to produce a
paresthetic effect, the two frequencies can be considered
corresponding parameters. Based on patient feedback to the second
pulses, the first signal delivery parameters are changed (process
portion 353), generally by the practitioner.
[0024] As noted above, some patients may experience pain while
standing or walking, but not while lying down. Because the patient
is typically lying down while the practitioner adjusts the signal
delivery parameters, it may not be immediately evident that the
parameters are creating the desired effect in the patient.
Accordingly, the practitioner can position the signal delivery
device at a site expected to produce the desired anesthetic,
non-paresthetic effect in the patient, and can accompany the
signals intended to produce that effect with signals that
deliberately produce a patient-detectable paresthetic effect. When
the patient begins to report a paresthetic effect, the practitioner
can have an enhanced degree of confidence that the signal delivery
parameters that are common to both the first pulses (which produce
the anesthetic effect) and the second pulses (which produce the
paresthetic effect) are properly selected. These signal delivery
parameters can include the location at which the signal is
delivered, the strength (e.g., amplitude) of the signal, and/or
other parameters. If, based on patient feedback to the second
pulses, the parameter values can be improved, the practitioner can
change the first signal delivery parameters, e.g., by moving the
lead, applying signals to different contacts on the lead, changing
signal strength and/or making other adjustments. In a particular
example, this arrangement can reduce the likelihood that the
practitioner will inadvertently increase the amplitude of the
anesthesia-producing first pulses to a level that will produce
discomfort and/or muscle activation when the patient changes
position. In other embodiments, other signal delivery parameters
may be adjusted, as described further below with reference to FIGS.
3B-3F. In any of these embodiments, the second signal delivery
parameters can also be changed, e.g., in parallel with changes to
the first signal delivery parameters, so that the practitioner
continues to receive feedback from the patient based on the
paresthetic effect created by the second pulses.
[0025] FIG. 3B illustrates another representative process 355 for
treating a patient, and includes creating an anesthetic,
non-paresthetic effect in the patient (process portion 356),
generally similar to process portion 351 described above. The
anesthetic, non-paresthetic effect is typically manifested as a
perceived reduction or elimination of pain, and so represents an
example of the second characteristic described above with reference
to FIG. 2. In process portion 357, the process 355 includes
providing an indication of a strength of the first pulses by
creating a patient-detectable paresthetic effect in the patient.
This can in turn include delivering to the patient's spinal cord
second pulses having a second set of signal delivery parameters
(process portion 358a), with the strength of the second pulses
being correlated with a strength of the first pulses (process
portion 358b) and with a first value of at least one parameter of
the first set being different than a second value of a
corresponding second parameter of the second set (process portion
358c). For example, the frequency of the first pulses may be
different than the frequency of the second pulses. In process
portion 359, the strengths of the first and second pulses are
changed in a parallel manner. For example, as the strength of the
first pulses is increased, the strength of the second pulses can
also be increased. Accordingly, when the patient reports a
sensation of paresthesia resulting from the second pulses, the
practitioner can effectively obtain an indication of the strength
of the first pulses, even though the patient may not be able to
report a direct effect of the first pulses. In one aspect of this
embodiment, the strengths of the first and second pulses may be
identical, and may be changed in identical manners. In other
embodiments, this may not be the case. For example, in a particular
embodiment, the practitioner may be aware of a typical offset
between the strength of a pulse that is suitable for creating an
anesthetic effect and the strength of a pulse that is sufficient to
create a paresthetic effect. In such instances, the practitioner
may build this offset into the manner in which the two sets of
pulses are changed to preserve a desired correlation between the
onset of a patient-detectable effect created by the second pulses
and an expected anesthetic effect created by the first pulses. The
amplitude or intensity of the second pulses can be significantly
less than that associated with standard SCS systems. This can be
the case for at least the reason that in at least some embodiments,
the second pulses are not necessarily intended to mask pain (as
they are in standard SCS treatments), but rather are intended to
create a patient-detectable sensation. When this is the case,
delivering the second pulses can use less energy than delivering
standard SCS pulses. In addition to or in lieu of this potential
benefit, the second pulses can allow the practitioner more
flexibility in setting an appropriate intensity level because a
wider range of intensity levels (e.g., extending to lower values
than are associated with standard SCS) are expected to produce the
desired patient sensation.
[0026] In addition to or in lieu of providing feedback that may be
used to adjust signal delivery parameters associated with the first
pulses (e.g., the anesthesia-producing pulses), aspects of the
foregoing process may be used to identify faults (e.g., defects,
abnormalities and/or unexpected states) associated with the system
at an early stage. For example, FIG. 3C illustrates a process 360
that includes creating an anesthetic, non-paresthetic effect in the
patient (process portion 361) that is undetected by the patient,
and that is accompanied by creating a patient-detectable
paresthetic effect (process portion 362) generally similar to
process portion 352 described above. In process portion 363, the
amplitudes of the first and second pulses are changed in parallel.
In one representative process, the amplitudes are increased and, in
other processes, the amplitudes can be decreased.
[0027] Process portion 364 includes identifying a fault with the
delivery of the first pulses based at least in part on the presence
or absence of a patient response to the changing amplitude of the
second pulses. For example, while the patient may be unable to
detect whether or not the first pulses are being delivered, the
practitioner can increase the amplitude of both the first and
second pulses to a point at which the practitioner would expect the
patient to report a paresthetic effect created by the second
pulses. If the patient fails to report such an effect, the
practitioner may be alerted to a fault in the signal delivery
system that applies to both delivery of the first pulses and the
second pulses. Accordingly, the practitioner can rectify the fault
and continue the process of establishing suitable signal delivery
parameters for the first pulses, and optionally, the second pulses
as well. The fault may be that the system is not on, that there is
an electrical discontinuity between the signal generator and the
lead contacts, that an element of the signal generator or lead has
failed, and/or that the system has another abnormality or
unexpected characteristic. In other embodiments, the fault can be
identified by the presence of a patient response, rather than the
absence of a patient response. For example, if the patient reports
a sensation when no sensation is expected (e.g., if the patient
reports muscle cramping, sensation and/or stimulation), this may
indicate a system fault. In other cases, this may indicate a
misplaced lead, or a patient with a lower than expected activation
threshold.
[0028] FIG. 3D illustrates a process 370 that includes directing
both the first and second pulses to the same target neural
population of the patient. Accordingly, process 370 includes
creating an anesthetic, non-paresthetic effect in a patient by
delivering to a target neural population at the patient's spinal
cord, first pulses having a first set of first signal delivery
parameters (process portion 371). The process 370 further includes
creating a paresthetic effect in the patient by delivering, to the
same target neural population, second pulses having characteristics
generally similar to those discussed above with reference to
process portion 352 (e.g., at least one parameter value differing
from a corresponding parameter value of the first pulses). In this
embodiment, the first and second pulses are delivered to the same
target neural population, for example, when it is expected that
other target neural populations may not have a known correlation
between patient responses to the second pulses, and patient effects
created by the first pulses. In cases where such a correlation is
known, the second signals can be applied to a different neural
population than the first pulses. For example, as is discussed
further with reference to FIGS. 5A and 5B, if one neural population
is susceptible to paresthesia but not anesthesia, the practitioner
may wish to apply the second pulses to a different neural
population than the first pulses.
[0029] FIG. 3E is a flow diagram illustrating a process 365 in
which a paresthetic effect is provided to the patient in response
to a patient request. Process 365 includes creating an anesthetic,
non-paresthetic effect in the patient by delivering, to a target
neural population at the patient's spinal cord, first pulses having
a first set of first signal delivery parameters (process portion
366). Process portion 367 includes supplementing the anesthetic,
non-paresthetic effect in the patient with a patient-detectable,
paresthetic effect, based on a request from the patient. This
process can in turn include delivering to the patient's spinal
cord, second pulses having a second set of signal delivery
parameters, with a first value of at least one first parameter of
the first set being different than a second value of a
corresponding second parameter of the second set. In a particular
embodiment, the patient may request the second pulses to emulate an
effect the patient is already familiar with, as described below
with reference to FIG. 3F.
[0030] FIG. 3F is a schematic block diagram of a process 375 for
treating a patient that, in general terms, includes emulating the
paresthesia-inducing effects of a conventional SCS device with a
device that provides both anesthesia and paresthesia. Accordingly,
the process 375 can include selecting a patient who previously
received paresthesia-inducing pulses from a first implanted spinal
cord modulator, and implanting a second spinal cord modulator in
that patient (process portion 376). In process portion 377, the
second spinal cord modulator is used to create an anesthetic,
non-paresthetic effect in the patient (process portion 378a), and
also a patient-detectable paresthetic effect (process portion
378b), using different signal delivery parameters (process portion
379a). The signal delivery parameters can be selected to emulate
the paresthesia-inducing pulses from the first implanted spinal
cord modulator (process portion 379b). This arrangement can be used
for patients who prefer to retain the paresthetic effect obtained
with a conventional SCS device, in addition to obtaining the
benefit of an anesthetic effect. The patient may want the
paresthetic effect for any of a variety of reasons, including but
not limited to the sense of familiarity it may provide, and/or the
pleasurable effect of the sensation.
[0031] In at least some instances, it may be desirable to the
physician or other practitioner to control the amplitude or
strength of the anesthesia-producing first pulses, and the patient
control the amplitude or strength of the paresthesia-producing
second pulses. Accordingly, the system 100 (FIG. 1) delivering the
pulses can allow the patient access to the amplitude control of the
second pulses, and restrict access to the amplitude control of the
first pulses to the practitioner. In this manner, the practitioner
can be assured that the anesthetic effect is provided automatically
at a selected level, and the patient can control at least some
aspects of the sensation-producing second pulses. This is a
representative example of the more general case in which the
amplitude (and/or other parameters) of the first and second pulses
are varied independently of each other. For example, the
practitioner may want to vary the frequency of the first pulses
while keeping the frequency of the second pulses constant. In other
embodiments, the practitioner may want to have the first and second
pulses applied with different duty cycles, different pulse widths,
different interpulse intervals, and/or other parameters, and so may
wish to have independent control over the values of these
parameters as they apply to the first pulses, independent of the
values of the these parameters as they apply to the second
pulses.
[0032] FIG. 4 is a partially schematic illustration of a lead body
111 that may be used to apply modulation to a patient in accordance
with any of the foregoing embodiments. In general, the lead body
111 includes a multitude of electrodes or contacts 120. When the
lead body 111 has a circular cross-sectional shape, as shown in
FIG. 4, the contacts 120 can have a generally ring-type shape and
can be spaced apart axially along the length of the lead body 111.
In a particular embodiment, the lead body 111 can include eight
contacts 120, identified individually as first, second, third . . .
eighth contacts 121, 122, 123 . . . 128. In general, one or more of
the contacts 120 are used to provide signals, and another one or
more of the contacts 120 provide a signal return path. Accordingly,
the lead body 111 can be used to deliver monopolar modulation
(e.g., if the return contact is spaced apart significantly from the
delivery contact), or bipolar modulation (e.g., if the return
contact is positioned close to the delivery contact and in
particular, at the same target neural population as the delivery
contact).
[0033] FIG. 5A illustrates a representative electrical signal wave
form 540a having first pulses 541a and second pulses 542a. In a
particular aspect of this embodiment, the first pulses 541a are
provided at a higher frequency than are the second pulses 542a. In
another embodiment, this relationship can be reversed. A single
second pulse 542a can be positioned between sequential bursts of
the first pulses 541a (as shown in FIG. 5A), or multiple second
pulses 542a can be provided between sequential bursts of the first
pulses 541a. In either of these embodiments, the first and second
pulses 541a, 542a can be provided to the same contact(s) e.g., so
that both sets of pulses are directed to the same target neural
population. In such instances, the first and second pulses 541a,
542a generally do not overlap temporally with each other.
Accordingly, the practitioner can maintain a suitable level of
control over the electric fields produced by each set of pulses.
Although the first and second pulses do not overlap, they can be
interleaved with each other in such a manner that the effects of
each set of pulses (e.g., anesthetic and paresthetic effects) can
temporarily overlap. Put another way, the patient can concurrently
receive an anesthetic effect and a paresthetic effect from the
interleaved pulses. As discussed above, the first and second pulses
can be applied to different neural populations in other
embodiments.
[0034] The first pulses 541a can be provided at a duty cycle that
is less than 100%. For example, as shown in FIG. 5A, the first
pulses 541a can be provided at a duty cycle of about 60%, meaning
that the first pulses 541a are active during 60% of the time
interval between sequential second pulses 542a. The first pulses
541a can be provided continuously during each burst (e.g., each
first pulse in a burst can be immediately followed by another first
burst), or an interpulse interval can be positioned between
neighboring first pulses 541a. In a representative embodiment, the
interpulse interval between first pulses 541a is 15 microseconds,
and in other embodiments, the interpulse interval can have other
values, including zero. In the embodiment shown in FIG. 5A, the
interpulse interval between neighboring second pulses 542a is
filled or partially filled with the first pulses 541a. The first
pulses 541a can also include an interphase interval between anodic
and cathodic portions of the pulse. The interphase interval can
also be 15 microseconds in a representative embodiment, and can
have other zero or non-zero values in other embodiments.
[0035] In general, the pulse width of the second pulses 542a can be
greater than that of the first pulses 541a (as shown in FIG. 5A).
In other embodiments, the second pulses 542a can have pulse widths
equal to or less than the pulse widths of the first pulses 541a.
The amplitude (e.g., current amplitude or voltage amplitude) of the
second pulses 542a can be less than the amplitude of the first
pulses 541a (as shown in FIG. 5A), or equal to the amplitude of the
first pulses 541a, or greater than the amplitude of the first
pulses 541a (as described below with reference to FIG. 5B),
depending upon whether or not it is beneficial to maintain an
offset between the respective amplitudes, as discussed above with
reference to FIG. 3B. In particular examples, the first pulses 541a
can be delivered at a frequency of from about 1.5 kHz to about 100
kHz, or from about 1.5 kHz to about 50 kHz. In more particular
embodiments, the first pulses 541a can be provided at frequencies
of from about 3 kHz to about 20 kHz, or from about 3 kHz to about
15 kHz, or from about 5 kHz to about 15 kHz, or from about 3 kHz to
about 10 kHz. The amplitude of the first pulses 541a can range from
about 0.1 mA to about 20 mA in a particular embodiment, and in
further particular embodiments, can range from about 0.5 mA to
about 10 mA, or about 0.5 mA to about 4 mA, or about 0.5 mA to
about 2.5 mA. In still further embodiments, the amplitude can be
from about 2.0 mA to about 3.5 mA, or from about 1 mA to about 5
mA, about 6 mA, or about 8 mA. The pulse width (e.g., for just the
cathodic phase of the pulses) can vary from about 10 microseconds
to about 333 microseconds. In further particular embodiments, the
pulse width of the first pulses 541a can range from about 25
microseconds to about 166 microseconds, or from about 33
microseconds to about 100 microseconds, or from about 50
microseconds to about 166 microseconds. The frequency of the second
pulses 542a can be in the range of from about 2 Hz to about 1.2
kHz, and in a more particular embodiment, about 60 Hz. The
amplitude of the second pulses 542a can be from about 1 mA to about
20 mA, and in a particular embodiment, from about 2 mA to about 10
mA. The pulse width of the second pulses 542a can range from about
10 microseconds to about 1,000 microseconds. In a further
particular embodiment, the pulse width of the second pulses can be
from about 100 microseconds to about 1,000 microseconds, and in a
still further particular embodiment, can be about 250 microseconds.
In at least some embodiments, it is expected that the foregoing
amplitudes will be suprathreshold. It is also expected that, in at
least some embodiments, the neural response to the foregoing
signals will be asynchronous. For example, the frequency of the
first pulses 541a can be selected to be higher (e.g., between twice
and ten times higher) than the refractory period of the target
neurons at the patient's spinal cord, which in at least some
embodiments is expected to produce an asynchronous response.
Further details of representative systems and methods for producing
asynchronous neural responses are included in pending U.S. patent
application Ser. No. 12/362,244 filed on Jan. 29, 2009 and
incorporated herein by reference.
[0036] FIG. 5B illustrates another electrical signal 540b having
first pulses 541b and second pulses 542b. In this particular
embodiment, the first pulses 541b are provided at a higher duty
cycle (e.g., about 85%) compared with that shown in FIG. 5A. The
second pulses 542b are also provided at an amplitude slightly
higher than that of the first pulses 541a.
[0037] The pulses shown in FIGS. 5A and 5B can be provided to
different patients, or to the same patient at different times, or
the pulses can be provided to the same patient at the same time,
but via different leads. For example, the patient may be implanted
with two leads generally similar to the lead shown in FIG. 4. The
first signal 540a is then applied to the first and second contacts
of one lead, and the second signal applied to the first and second
contacts of the other lead. In other embodiments, the signals can
be applied in any of a wide variety of manners, e.g., to two
8-contact leads, to one 8-contact lead and two 4-contact leads, to
four 4-contact leads, or to other lead arrangements. In any of
these embodiments, the second pulses can be applied to the same
target neural population as are the first pulses, e.g., when it is
expected that the target neural population will have both a
paresthetic response and an anesthetic response. In other
embodiments, the second pulses can be applied to a different neural
population than are the first pulses. For example, if the target
neural population to which the first pulses are applied is expected
to have an anesthetic response, but not a paresthetic response, the
second pulses can be applied to a different neural population. In
such a case, the paresthetic response at the second neural
population may still be used to influence the manner in which the
first pulses are applied to the first target neural population.
Further details of representative leads and associated systems and
methods are included in co-pending U.S. patent application Ser. No.
______, filed concurrently herewith, titled "Selective High
Frequency Spinal Cord Stimulation for Inhibiting Pain with Reduced
Side Effects, and Associated Systems and Methods" (Attorney Docket
No. 66245.8020US1), and incorporated herein by reference.
[0038] FIG. 5C illustrates still another signal 540c having
spaced-apart bursts of first pulses 541c. Bursts of second pulses
542c are interleaved with the bursts of first pulses 541c. For
example, a single burst of second pulses 542c may be positioned
between neighboring bursts of first pulses 541c. This arrangement
can be appropriate in cases where multiple, uninterrupted second
pulses 542c are suitable for creating a paresthetic effect, and the
resulting separation between bursts of the first pulses 541c does
not detract significantly from the anesthetic effect created by the
first pulses 541c.
[0039] In one aspect of the embodiment shown in FIGS. 5A and 5B,
the first and second pulses are the only pulses provided to the
corresponding signal delivery element, and are provided to, for
example, the first and second contacts 121, 122 of the lead body
110 shown in FIG. 4. In other embodiments, these signals may be
applied to other contacts or combinations of contacts. For example,
FIG. 5D illustrates an embodiment in which a first signal 540d
applies corresponding first and second pulses 541d, 542d to a
selected pair of contacts (e.g., the first and second contacts 121,
122 shown in FIG. 4) and a second signal 540e applies first and
second pulses 541e, 542e to another pair of contacts (e.g., the
seventh and eighth contacts 127, 128 shown in FIG. 4). The high
frequency first pulses 541d, 541e are provided simultaneously at
each pair of contacts, while the low second frequency pulses 542d,
542e are staggered in time and location. This arrangement may be
used when the practitioner wishes to provide a broader field with
the first pulses 541d, 541e. In other embodiments, the first and
second pulses may be provided to other contacts, and/or in
accordance with other timing patterns, based generally on a
patient-specific basis.
[0040] In any of the foregoing embodiments, the signal delivery
parameters selected for any of the first pulses 541a-e (referred to
collectively as first pulses 541) and the second pulses 542a-e
(referred to collectively as second pulses 542) can be selected to
produce an anesthetic, non-paresthetic effect, and a paresthetic
effect, respectively. As discussed above, in at least some
embodiments, the first pulses 541 will be provided at a higher
frequency than the second pulses 542. For example, the first pulses
541 can be provided at a frequency of from about 1.5 kHz to about
50 kHz, while the second pulses 542 can be provided in a range of
from about 2 Hz to about 1.2 kHz. In other embodiments, the pulses
can have different relationships. For example, the second pulses
542 can be within a 3 kHz to 10 kHz range, but at a frequency less
than the first pulses 541.
[0041] FIG. 6 is a cross-sectional illustration of the spinal cord
191 and an adjacent vertebra 195 (based generally on information
from Crossman and Neary, "Neuroanatomy," 1995 (published by
Churchill Livingstone)), along with selected representative
locations for representative lead bodies 110 (shown as lead bodies
110a-110d) in accordance with several embodiments of the
disclosure. The spinal cord 191 is situated between a ventrally
located ventral body 196 and the dorsally located transverse
process 198 and spinous process 197. Arrows V and D identify the
ventral and dorsal directions, respectively. In particular
embodiments, the vertebra 195 can be at T9, T10, T11 and/or T12
(e.g., for axial low back pain and/or leg pain) and in other
embodiments, the lead bodies can be placed at other locations. The
lead body can be positioned to provide the same or different pulses
to different vertebral levels (e.g., T9 and T10). The spinal cord
191 itself is located within the dura mater 199, which also
surrounds portions of the nerves exiting the spinal cord 191,
including the dorsal roots 193 and dorsal root ganglia 194.
[0042] The lead body is generally positioned to preferentially
modulate tactile fibers (e.g., to produce the paresthetic effect
described above) and to avoid modulating fibers associated with
nociceptive pain transmission. In a particular embodiment, a lead
body 110a can be positioned centrally in a lateral direction (e.g.,
aligned with the spinal cord midline 189) to provide signals
directly to the spinal cord 191. In other embodiments, the lead
body can be located laterally from the midline 189. For example,
the lead body can be positioned just off the spinal cord midline
189 (as indicated by lead body 110b), and/or proximate to the
dorsal root 193 or dorsal root entry zone 188 (e.g., 1-4
millimeters from the spinal cord midline 189, as indicated
generally by lead body 110c), and/or proximate to the dorsal root
ganglion 194 (as indicated by lead body 110d). Other suitable
locations for the lead body 110 include the "gutter," also located
laterally from the midline 189. In still further embodiments, the
lead bodies may have other locations proximate to the spinal cord
191 and/or proximate to other target neural populations, e.g.,
laterally from the midline 189 and medially from the dorsal root
ganglion 194. In any of the foregoing embodiments, electrical
pulses may be applied to the lead body 110 to provide both a
paresthetic and an anesthetic effect, as described above. As
discussed above, the patient can be implanted with a single lead
body (e.g., one of the lead bodies 110a-110d) or multiple lead
bodies (e.g., combinations of the lead bodies 110a-110d).
[0043] From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the invention. For example, the signal
delivery parameters may have values other than those specifically
described above, but which are also selected to produce anesthetic
or paresthetic effects in the manner described above. Particular
embodiments were described above in the context of signals applied
to the patient's spinal cord, but in other embodiments, signals
(e.g., signals creating an anesthetic, non-paresthetic effect,
and/or signals creating a paresthetic effect) can be applied to
other neural populations, including, but limited to, peripheral
nerves. For example, such methods can include applying first pulses
to the patient's spinal cord to create an anesthetic,
non-paresthetic effect, and applying second pulses to a peripheral
nerve to create a paresthetic effect. Systems suitable for carrying
out embodiments of the foregoing techniques are included in
co-pending U.S. application Ser. No. ______, filed concurrently
herewith, titled "Devices for Controlling High Frequency Spinal
Cord Stimulation for Inhibiting Pain, and Associated Systems and
Methods" (Attorney Docket No. 66245.8024US), and incorporated
herein by reference.
[0044] Certain aspects of the invention described in the context of
particular embodiments may be combined or eliminated in other
embodiments. For example, the wave forms described above with
reference to FIGS. 5A-5D may be combined in further embodiments. In
addition, while advantages associated with certain embodiments have
been described and the context of those embodiments, other
embodiments may also exhibit such advantages. Not all embodiments
need necessarily exhibit such advantages to fall within the scope
of the present disclosure. Accordingly, the disclosure and
associated technology can encompass other embodiments not expressly
shown or described herein.
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