U.S. patent application number 12/771763 was filed with the patent office on 2011-04-21 for assignment and manipulation of implantable leads in different anatomical regions with image background.
This patent application is currently assigned to Medtronic, Inc.. Invention is credited to Dennis J. Bourget, Lynn A. Davenport, Jon P. Davis, Steven M. Goetz, Brent A. Huhta, Shanthi Kandikonda, Jason D. Rahn, Rajeev M. Sahasrabudhe, Ashish Singal.
Application Number | 20110093051 12/771763 |
Document ID | / |
Family ID | 43879903 |
Filed Date | 2011-04-21 |
United States Patent
Application |
20110093051 |
Kind Code |
A1 |
Davis; Jon P. ; et
al. |
April 21, 2011 |
ASSIGNMENT AND MANIPULATION OF IMPLANTABLE LEADS IN DIFFERENT
ANATOMICAL REGIONS WITH IMAGE BACKGROUND
Abstract
This disclosure describes techniques for combining an image of a
region defined by the user to receive stimulation therapy with an
image of representation of leads which will deliver the therapy to
the defined region, and importing the combined image on an
implantable medical device connected to the leads that will deliver
the stimulation therapy. During the process of combining the
images, the user manipulates one or both of the images to combine
the image such that the leads are placed for accurate therapy
delivery. In some examples where more than one region is to receive
stimulation therapy, each region can have a different image and/or
a different set of leads associated therewith, and a combined image
of each region may be produced, manipulated, and imported on the
implantable medical device.
Inventors: |
Davis; Jon P.; (St. Michael,
MN) ; Goetz; Steven M.; (North Oaks, MN) ;
Singal; Ashish; (Blaine, MN) ; Davenport; Lynn
A.; (Roseville, MN) ; Bourget; Dennis J.; (St.
Michael, MN) ; Sahasrabudhe; Rajeev M.; (Maple Grove,
MN) ; Huhta; Brent A.; (Big Lake, MN) ;
Kandikonda; Shanthi; (Woodbury, MN) ; Rahn; Jason
D.; (Andover, MN) |
Assignee: |
Medtronic, Inc.
Minneapolis
MN
|
Family ID: |
43879903 |
Appl. No.: |
12/771763 |
Filed: |
April 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61253756 |
Oct 21, 2009 |
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61260707 |
Nov 12, 2009 |
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61253766 |
Oct 21, 2009 |
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61260712 |
Nov 12, 2009 |
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61253759 |
Oct 21, 2009 |
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61260644 |
Nov 12, 2009 |
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Current U.S.
Class: |
607/116 |
Current CPC
Class: |
A61N 1/37247 20130101;
A61N 1/37264 20130101; A61N 1/37211 20130101; A61N 1/372
20130101 |
Class at
Publication: |
607/116 |
International
Class: |
A61N 1/00 20060101
A61N001/00 |
Claims
1. A programmer for an implantable medical device comprising: a
processor that associates one or more implantable elements of an
implantable medical device with one or more anatomical implant
regions of a patient; and a user interface that receives user input
selecting one of the anatomical implant regions, and receives user
input specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
2. The programmer of claim 1, wherein the user interface presents a
graphical representation of the selected anatomical implant region
with the one or more implantable elements associated with the
selected anatomical implant region.
3. The programmer of claim 1, wherein the user interface presents
an image of the selected anatomical implant region with the one or
more implantable elements associated with the selected anatomical
implant region.
4. The programmer of claim 3, wherein the image comprises a
fluoroscopic image.
5. The programmer of claim 3, wherein the processor is configured
to obtain the image in response to a user input.
6. The programmer of claim 3, wherein the image comprises an image
stored in the implantable medical device, the programmer further
comprising a telemetry module that retrieves the image from the
implantable medical device.
7. The programmer of claim 1, wherein the implantable medical
device includes an electrical stimulator, the one or more
implantable elements include one or more leads that deliver
stimulation from the electrical stimulator to the one or more
anatomical implant regions, and the therapy parameters specify one
or more therapy parameters for delivery of electrical stimulation
by the electrical stimulator via the one or more leads.
8. The programmer of claim 1, wherein the implantable medical
device includes a fluid delivery device, the one or more
implantable elements include one or more fluid delivery catheters
that deliver the fluid from the device to the one or more
anatomical implant regions, and the therapy parameters specify one
or more therapy parameters for delivery of fluid stimulation by the
fluid delivery device via the one or more catheters.
9. The programmer of claim 1, wherein the one or more anatomical
implant regions include at least a first region and a second
region, the user interface receiving user input selecting one of
the first and second regions, and presenting a representation of
the selected region with the one or more implantable elements
associated with the selected anatomical implant region and with
user input media to receive the user input specifying the one or
more therapy parameters for the one or more implantable elements
associated with the selected anatomical implant region.
10. A method comprising: associating one or more implantable
elements of an implantable medical device with one or more
anatomical implant regions of a patient; and receiving user input
selecting one of the anatomical implant regions, and receiving user
input specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
11. The method of claim 10, further comprising presenting a
graphical representation of the selected anatomical implant region
with the one or more implantable elements associated with the
selected anatomical implant region.
12. The method of claim 10, further comprising presenting an image
of the selected anatomical implant region with the one or more
implantable elements associated with the selected anatomical
implant region.
13. The method of claim 12, wherein the image comprises a
fluoroscopic image.
14. The method of claim 12, further comprising obtaining the image
in response to a user input.
15. The method of claim 12, wherein the image comprises an image
stored in the implantable medical device, the method further
comprising retrieving the image from the implantable medical
device.
16. The method of claim 10, wherein the implantable medical device
includes an electrical stimulator, the one or more implantable
elements include one or more leads that deliver stimulation from
the electrical stimulator to the one or more anatomical implant
regions, and the therapy parameters specify one or more therapy
parameters for delivery of electrical stimulation by the electrical
stimulator via the one or more leads.
17. The method of claim 10, wherein the implantable medical device
includes a fluid delivery device, the one or more implantable
elements include one or more fluid delivery catheters that deliver
the fluid from the device to the one or more anatomical implant
regions, and the therapy parameters specify one or more therapy
parameters for delivery of fluid stimulation by the fluid delivery
device via the one or more catheters.
18. The method of claim 10, wherein the one or more anatomical
implant regions include at least a first region and a second
region, the method further comprising receiving user input
selecting one of the first and second regions, and presenting a
representation of the selected region with the one or more
implantable elements associated with the selected anatomical
implant region and with user input media to receive the user input
specifying the one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
implant region.
19. A device comprising: means for associating one or more
implantable elements of an implantable medical device with one or
more anatomical implant regions of a patient; and means for
receiving user input selecting one of the anatomical implant
regions, and receiving user input specifying one or more therapy
parameters for the one or more implantable elements associated with
the selected anatomical region.
20. The device of claim 19, further comprising means for presenting
a graphical representation of the selected anatomical implant
region with the one or more implantable elements associated with
the selected anatomical implant region.
21. The device of claim 19, further comprising means for presenting
an image of the selected anatomical implant region with the one or
more implantable elements associated with the selected anatomical
implant region.
22. The device of claim 21, wherein the image comprises a
fluoroscopic image.
23. The device of claim 21, further comprising means for obtaining
the image in response to a user input.
24. The device of claim 21, wherein the image comprises an image
stored in the implantable medical device, the device further
comprising means for retrieving the image from the implantable
medical device.
25. The device of claim 19, wherein the implantable medical device
includes an electrical stimulator, the one or more implantable
elements include one or more leads that deliver stimulation from
the electrical stimulator to the one or more anatomical implant
regions, and the therapy parameters specify one or more therapy
parameters for delivery of electrical stimulation by the electrical
stimulator via the one or more leads.
26. The device of claim 19, wherein the implantable medical device
includes a fluid delivery device, the one or more implantable
elements include one or more fluid delivery catheters that deliver
the fluid from the device to the one or more anatomical implant
regions, and the therapy parameters specify one or more therapy
parameters for delivery of fluid stimulation by the fluid delivery
device via the one or more catheters.
27. The device of claim 19, wherein the one or more anatomical
implant regions include at least a first region and a second
region, the device further comprising means for receiving user
input selecting one of the first and second regions, and presenting
a representation of the selected region with the one or more
implantable elements associated with the selected anatomical
implant region and with user input media to receive the user input
specifying the one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
implant region.
28. A computer-readable medium comprising instructions that, upon
execution, cause a processor to: associate one or more implantable
elements of an implantable medical device with one or more
anatomical implant regions of a patient; and receive user input
selecting one of the anatomical implant regions, and receiving user
input specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
29. The computer-readable medium of claim 28, further comprising
instructions that cause the processor to present a graphical
representation of the selected anatomical implant region with the
one or more implantable elements associated with the selected
anatomical implant region.
30. The computer-readable medium of claim 28, further comprising
instructions that cause the processor to present an image of the
selected anatomical implant region with the one or more implantable
elements associated with the selected anatomical implant
region.
31. The computer-readable medium of claim 30, wherein the image
comprises a fluoroscopic image.
32. The computer-readable medium of claim 30, further comprising
instructions that cause the processor to obtain the image in
response to a user input.
33. The computer-readable medium of claim 30, wherein the image
comprises an image stored in the implantable medical device, the
computer-readable medium further comprising instructions that cause
the processor to retrieve the image from the implantable medical
device.
34. The computer-readable medium of claim 28, wherein the
implantable medical device includes an electrical stimulator, the
one or more implantable elements include one or more leads that
deliver stimulation from the electrical stimulator to the one or
more anatomical implant regions, and the therapy parameters specify
one or more therapy parameters for delivery of electrical
stimulation by the electrical stimulator via the one or more
leads.
35. The computer-readable medium of claim 28, wherein the
implantable medical device includes a fluid delivery device, the
one or more implantable elements include one or more fluid delivery
catheters that deliver the fluid from the device to the one or more
anatomical implant regions, and the therapy parameters specify one
or more therapy parameters for delivery of fluid stimulation by the
fluid delivery device via the one or more catheters.
36. The computer-readable medium of claim 28, wherein the one or
more anatomical implant regions include at least a first region and
a second region, the computer-readable medium further comprising
instructions that cause the processor to receive user input
selecting one of the first and second regions, and present a
representation of the selected region with the one or more
implantable elements associated with the selected anatomical
implant region and with user input media to receive the user input
specifying the one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
implant region.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/253,756, titled "STORING IMAGE OF THERAPY REGION
IN IMPLANTABLE MEDICAL DEVICE," filed on Oct. 21, 2009; U.S.
Provisional Application No. 61/260,707, titled "STORING IMAGE OF
THERAPY REGION IN IMPLANTABLE MEDICAL DEVICE," filed on Nov. 12,
2009; U.S. Provisional Application No. 61/253,766, titled
"ASSIGNMENT AND MANIPULATION OF IMPLANTABLE LEADS IN DIFFERENT
ANATOMICAL REGIONS WITH IMAGE BACKGROUND," filed on Oct. 21, 2009;
U.S. Provisional Application No. 61/260,712, entitled "ASSIGNMENT
AND MANIPULATION OF IMPLANTABLE LEADS IN DIFFERENT ANATOMICAL
REGIONS WITH IMAGE BACKGROUND," filed on Nov. 12, 2009; U.S.
Provisional Application No. 61/253,759, titled, "MANAGING
ELECTRICAL STIMULATION THERAPY BASED ON VARIABLE ELECTRODE
COMBINATIONS," filed on Oct. 21, 2009; and U.S. Provisional
Application No. 61/260,644, titled, "MANAGING ELECTRICAL
STIMULATION THERAPY BASED ON VARIABLE ELECTRODE COMBINATIONS,"
filed on Nov. 12, 2009, the entire contents of each being
incorporated herein by reference.
TECHNICAL FIELD
[0002] The disclosure relates to medical devices and, more
particularly, to medical devices that deliver electrical
stimulation therapy.
BACKGROUND
[0003] Medical devices may be used to treat a variety of medical
conditions. Medical electrical stimulation devices, for example,
may deliver electrical stimulation therapy to a patient via
implanted electrodes. Electrical stimulation therapy may include
stimulation of nerve, muscle, or brain tissue, or other tissue
within a patient. An electrical stimulation device may be fully
implanted within the patient. For example, an electrical
stimulation device may include an implantable electrical
stimulation generator and one or more implantable leads carrying
electrodes. Alternatively, the electrical stimulation device may
comprise a leadless stimulator. In some cases, implantable
electrodes may be coupled to an external electrical stimulation
generator via one or more percutaneous leads or fully implanted
leads.
[0004] Medical electrical stimulators may be used to deliver
electrical stimulation therapy to patients to relieve a variety of
symptoms or conditions such as chronic pain, tremor, Parkinson's
disease, depression, epilepsy, urinary or fecal incontinence,
pelvic pain, sexual dysfunction, obesity, or gastroparesis. An
electrical stimulator may be configured to deliver electrical
stimulation therapy via leads that include electrodes implantable
proximate to the spinal cord, pelvic nerves, gastrointestinal
organs, peripheral nerves, or within the brain of a patient.
Stimulation proximate the spinal cord and within the brain are
often referred to as spinal cord stimulation (SCS) and deep brain
stimulation (DBS), respectively.
[0005] A clinician selects values for a number of programmable
stimulation parameters in order to define the electrical
stimulation therapy to be delivered to a patient. For example, the
clinician may select a current or voltage amplitude of the
stimulation, and various characteristics of the stimulation
waveform. In addition, the clinician may specify an electrode
configuration used to deliver stimulation, including selected
electrode combinations and electrode polarities. If the stimulation
is delivered in the form of pulses, for example, the clinician may
specify a pulse width and pulse rate. A set of parameter values may
be referred to as a stimulation program. A program group may
include multiple programs. Multiple programs in a program group may
be delivered on a simultaneous, time-interleaved, or overlapping
basis.
SUMMARY
[0006] Generally, this disclosure describes techniques for
creating, assigning, and manipulating implanted leads in different
anatomical regions utilizing a graphical view of the leads and an
image of the regions to which the leads are to deliver electrical
stimulation therapy.
[0007] In one example, the disclosure is directed to a programmer
for an implantable medical device comprising a processor that
associates one or more implantable elements of an implantable
medical device with one or more anatomical implant regions of a
patient, and a user interface that receives user input selecting
one of the anatomical implant regions, and receives user input
specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
[0008] In another example, the disclosure is directed to a method
comprising associating one or more implantable elements of an
implantable medical device with one or more anatomical implant
regions of a patient, and receiving user input selecting one of the
anatomical implant regions, and receiving user input specifying one
or more therapy parameters for the one or more implantable elements
associated with the selected anatomical region.
[0009] In another example, the disclosure is directed to a device
comprising means for associating one or more implantable elements
of an implantable medical device with one or more anatomical
implant regions of a patient, and means for receiving user input
selecting one of the anatomical implant regions, and receiving user
input specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
[0010] In another example, the disclosure is directed to a
computer-readable medium comprising instructions that, upon
execution, cause a processor to associate one or more implantable
elements of an implantable medical device with one or more
anatomical implant regions of a patient, and receive user input
selecting one of the anatomical implant regions, and receiving user
input specifying one or more therapy parameters for the one or more
implantable elements associated with the selected anatomical
region.
[0011] The details of one or more aspects of the disclosure are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a conceptual diagram illustrating an example
therapy system that includes an implantable stimulator coupled to a
stimulation lead.
[0013] FIG. 2 is a conceptual diagram illustrating another example
therapy system that includes an implantable stimulator coupled to a
stimulation lead.
[0014] FIG. 3 is a block diagram illustrating various example
components of an implantable electrical stimulator.
[0015] FIG. 4 is a block diagram illustrating various example
components of an external programmer.
[0016] FIG. 5 is a block diagram illustrating various components of
an example electrical stimulation generator for use in the
implantable electrical stimulator of FIG. 3.
[0017] FIGS. 6A-6L illustrate an exemplary sequence of programmer
screens, in accordance with this disclosure.
[0018] FIG. 7 is a flow diagram illustrating example operation of a
programmer to create, assign, and manipulate leads in different
regions, in accordance with this disclosure.
DETAILED DESCRIPTION
[0019] This disclosure describes techniques for creating,
assigning, and manipulating implanted leads in different anatomical
regions utilizing a graphical view of the leads and an image of the
regions to which the leads are to deliver electrical stimulation
therapy. The examples of this disclosure may provide the user with
the ability to accurately define a lead image relative to an
anatomical target, which may be helpful in accurately programming
stimulation fields. The techniques of this disclosure describe how
to organize, assign, and manipulate leads based on an optional
anatomical image background.
[0020] In one example, the user may utilize a user interface to
assign implanted leads to one or more regions in a patient, where
the regions represent the physical implant location of the leads in
the patient body. The user interface may allow the user to view all
the leads, or to view the leads only assigned to a selected region.
The graphical representation of the leads, which is presented to
the user on the user interface, may be used to represent the leads
relative to the physical implantation location. In another example,
the user may import an anatomical image, e.g., fluoroscopy image,
X-ray image, MRI image, graphical representation of the anatomical
region, or the like, which may be then presented in the background
as a reference for one or more of the anatomical regions programmed
by the user. The user may also utilize the user interface to
manipulate the graphical representation of the leads to match the
leads' actual implanted orientation at the implant location for one
or more regions. In some examples, the actual leads may be visible
on the imported image in the background, and utilized as a
reference to adjust the graphical representation of the leads to
match the actual leads' orientation and position. In one example,
the leads in each region may be programmed and manipulated
individually based on the region, and independently from the other
regions of the patient.
[0021] FIG. 1 is a conceptual diagram illustrating an example
system 2 including an implantable electrical stimulator 4 that may
be used to deliver stimulation therapy to patient 6. Patient 6
ordinarily, but not necessarily, will be a human. Generally,
therapy system 2 includes implantable electrical stimulator 4 that
delivers electrical stimulation to patient 6 via one or more
implantable electrodes 11. The implantable electrodes 11 may be
deployed on one or more implantable medical leads, such as
implantable medical lead 10, and in some cases on a can electrode.
The electrical stimulation may be in the form of controlled current
or voltage pulses or substantially continuous waveforms.
[0022] Various parameters of the pulses or waveforms may be defined
by one or more stimulation program. The pulses or waveforms may be
delivered substantially continuously or in bursts, segments, or
patterns, and may be delivered alone or in combination with pulses
or waveforms defined by one or more other stimulation programs.
Although FIG. 1 shows a fully implantable stimulator 4, techniques
described in this disclosure may be applied to external stimulators
having electrodes deployed via percutaneously implantable leads
with a patch electrode or other indifferent electrode attached
externally to serve as the can or case. One or more of the
electrodes may be located on a housing 14, i.e., "can" or "case,"
of the implantable stimulator 4. In addition, in some cases,
implantable electrodes may be deployed on a leadless
stimulator.
[0023] In the example illustrated in FIG. 1, implantable stimulator
4 is implanted within a subcutaneous pocket in a clavicle region of
patient 6. Stimulator 4 generates programmable electrical
stimulation, e.g., a current waveform or current pulses, and
delivers the stimulation via an implantable medical lead 10
carrying an array of implantable stimulation electrodes 11. In some
cases, multiple implantable leads may be provided. In the example
of FIG. 1, a distal end of lead 10 is bifurcated and includes two
lead segments 12A and 12B (collectively "lead segments 12"). Lead
segments 12A and 12B each include a set of electrodes forming part
of the array of electrodes 11. In various examples, lead segments
12A and 12B may each carry four, eight, twelve, sixteen, or more
electrodes. In FIG. 1, each lead segment 12A, 12B carries four
electrodes, configured as ring electrodes at different axial
positions near the distal ends of the lead segments. Throughout the
remainder of this disclosure, for purposes of simplicity, the
disclosure may generally refer to electrodes carried on "leads"
rather than "lead segments."
[0024] FIG. 1 further depicts a housing, or can, electrode 13.
Housing electrode 13 may be formed integrally with an outer surface
of hermetically-sealed housing 14 of implantable stimulator 4, also
referred to in this disclosure as implantable medical device (IMD)
4, or otherwise coupled to housing 14. In one example, housing
electrode 13 may be described as an active, non-detachable
electrode on the surface of the IMD. In some examples, housing
electrode 13 is defined by an uninsulated portion of an outward
facing portion of housing 14 of IMD 4. Other divisions between
insulated and uninsulated portions of housing 14 may be employed to
define two or more housing electrodes, which may be referred to as
case or can electrodes. In some examples, housing electrode 13
comprises substantially all of housing 14, one side of housing 14,
a portion of the housing 14, or multiple portions of housing 14. In
other examples, electrode 13 may be formed by an electrode on a
dedicated short lead extending from housing 14. As a further
alternative, housing electrode 13 may be provided on a proximal
portion of one of the leads carrying electrodes 11. The proximal
portion may be closely adjacent to housing 14, e.g., at or near a
point at which lead 10 is coupled to the housing, such as adjacent
to a lead connection header 8 of the housing. In another example, a
patch electrode or other indifferent electrode may be attached
externally to serve as the can or case.
[0025] In some examples, lead 10 may also carry one or more sense
electrodes to permit implantable stimulator 4 to sense electrical
signals from patient 6. Some of the stimulation electrodes may be
coupled to function as stimulation electrodes and sense electrodes
on a selective basis. In other examples, implantable stimulator 4
may be coupled to one or more leads which may or may not be
bifurcated. In such examples, the leads may be coupled to
implantable stimulator 4 via a common lead extension or via
separate lead extensions.
[0026] A proximal end of lead 10 may be both electrically and
mechanically coupled to header 8 on implantable stimulator 4 either
directly or indirectly via a lead extension. Conductors in the lead
body may electrically connect stimulation electrodes located on
lead segments 12 to implantable stimulator 4. Lead 10 traverses
from the implant site of implantable stimulator 4 along the neck of
patient 6 to cranium 18 of patient 6 to access brain 16. Lead
segments 12A and 12B are implanted within the right and left
hemispheres, respectively, in order to deliver electrical
stimulation to one more regions of brain 16, which may be selected
based on the patient condition or disorder.
[0027] Implantable stimulator 4 may deliver, for example, deep
brain stimulation (DBS) or cortical stimulation (CS) therapy to
patient 6 via the electrodes carried by, i.e., located on, lead
segments 12 to treat any of a variety of neurological disorders or
diseases. Example neurological disorders may include depression,
dementia, obsessive-compulsive disorder and movement disorders,
such as Parkinson's disease, spasticity, epilepsy, and dystonia.
DBS also may be useful for treating other patient conditions, such
as migraines and obesity. However, the disclosure is not limited to
the configuration of lead 10 shown in FIG. 1, or to the delivery of
DBS or CS therapy.
[0028] Lead segments 12A, 12B may be implanted within a desired
location of brain 16 through respective holes in cranium 18. Lead
segments 12A, 12B may be placed at any location within brain 16
such that the electrodes located on lead segments 12A, 12B are
capable of providing electrical stimulation to targeted tissue
during treatment. Example locations for lead segments 12A, 12B
within brain 26 may include the pedunculopontine nucleus (PPN),
thalamus, basal ganglia structures (e.g., globus pallidus,
substantia nigra, subthalmic nucleus), zona inserta, fiber tracts,
lenticular fasciculus (and branches thereof), ansa lenticularis,
and/or the Field of Forel (thalamic fasciculus). In the case of
migraines, lead segments 12 may be implanted to provide stimulation
to the visual cortex of brain 16 in order to reduce or eliminate
migraine headaches afflicting patient 6. However, the target
therapy delivery site may depend upon the patient condition or
disorder being treated.
[0029] The electrodes of lead segments 12A, 12B are shown as ring
electrodes. Ring electrodes are commonly used in DBS applications
because they are simple to program and are capable of delivering an
electrical field to any tissue adjacent to lead segments 12A, 12B.
In other implementations, the electrodes of lead segments 12A, 12B
may have different configurations. For example, the electrodes of
lead segments 12A, 12B may have a complex electrode array geometry
that is capable of producing shaped electrical fields. The complex
electrode array geometry may include multiple electrodes (e.g.,
partial ring or segmented electrodes) around the perimeter of each
lead segments 12A, 12B, rather than one ring electrode. In this
manner, electrical stimulation may be directed in a specific
direction from lead segments 12 to enhance therapy efficacy and
reduce possible adverse side effects from stimulating a large
volume of tissue. In alternative examples, lead segments 12 may
have shapes other than elongated cylinders as shown in FIG. 1. For
example, lead segments 12 may be paddle leads, spherical leads,
bendable leads, or any other type of shape effective in treating
patient 6.
[0030] Therapy system 2 also may include a clinician programmer 20
and/or a patient programmer 22. Clinician programmer 20 may be a
handheld computing device that permits a clinician to program
stimulation therapy for patient 6 via a user interface, e.g., using
input keys and a display. For example, using clinician programmer
20, the clinician may specify stimulation parameters, i.e., create
programs, for use in delivery of stimulation therapy. Clinician
programmer 20 may support telemetry (e.g., radio frequency (RF)
telemetry) with implantable stimulator 4 to download programs and,
optionally, upload operational or physiological data stored by
implantable stimulator 4. In this manner, the clinician may
periodically interrogate implantable stimulator 4 to evaluate
efficacy and, if necessary, modify the programs or create new
programs. In some examples, clinician programmer 20 transmits
programs to patient programmer 22 in addition to or instead of
implantable stimulator 4. In some examples, patient programmer 22
may serve as the clinician programmer.
[0031] Like clinician programmer 20, patient programmer 22 may be a
handheld computing device. Patient programmer 22 may also include a
display and input keys to allow patient 6 to interact with patient
programmer 22 and implantable stimulator 4. In this manner, patient
programmer 22 provides patient 6 with a user interface for control
of the stimulation therapy delivered by implantable stimulator 4.
For example, patient 6 may use patient programmer 22 to start, stop
or adjust electrical stimulation therapy. In particular, patient
programmer 22 may permit patient 6 to adjust stimulation parameters
of a program such as duration, current or voltage amplitude, pulse
width and pulse rate. Patient 6 may also select a program, e.g.,
from among a plurality of stored programs, as the present program
to control delivery of stimulation by implantable stimulator 4.
[0032] In accordance with various example techniques described in
this disclosure, a programmer such as, for example, clinician
programmer 20 and/or patient programmer 22 may be used to program
leads or lead groups by assigning them to anatomical regions in
which they apply the stimulation therapy. The leads or lead groups
may be programmed in a region-based manner, where each defined
region and its corresponding leads may be programmed independently
of any other regions. In one example, a programmer may be used to
graphically program the leads or lead groups by defining desired
stimulation field(s) within zones on or adjacent to one or more
leads, and generating the stimulation that would achieve the
stimulation field. In particular, a programmer may be used for
translating one or more user input stimulation zones into a set of
electrodes for delivering electrical stimulation therapy to a
patient, determining the variable electrical stimulation
contributions of each electrode to the zone, and determining
amplitudes of electrical stimulation when using zone-based
programming. A programmer may also be used for graphically
representing the stimulation zone and receiving input from a user
that manipulates the shape and position of the zone. In another
example, a programmer may be used to program the leads or lead
groups by defining the stimulation parameters associated with each
lead or group of leads, by selecting electrodes and the
corresponding parameters, e.g., amplitude, pulse rate, pulse width,
etc. In one example, the programmer may be used to program the case
electrodes by defining stimulation parameters associated with the
case electrodes.
[0033] In some examples, implantable stimulator 4 delivers
stimulation according to a group of programs at a given time. Each
program of such a program group may include respective values for
each of a plurality of therapy parameters, such as respective
values for each of current or voltage amplitude, pulse width, pulse
shape, pulse rate and electrode configuration (e.g., electrode
combination and polarity). Implantable stimulator 4 may interleave
pulses or other signals according to the different programs of a
program group, e.g., cycle through the programs, to simultaneously
treat different symptoms or different body regions, or provide a
combined therapeutic effect. In such examples, clinician programmer
20 may be used to create programs, and assemble the programs into
program groups. Patient programmer 22 may be used to adjust
stimulation parameters of one or more programs of a program group,
and select a program group, e.g., from among a plurality of stored
program groups, as the current program group to control delivery of
stimulation by implantable stimulator 4. In another example, the
groups of programs may be organized in slots according to the
target area of pain, where each slot may be made up of alternative
programs with different stimulation parameters targeting the same
area of pain, and a patient may change the effective program within
a slot, without affecting the selected programs in other slots.
[0034] Implantable stimulator 4, clinician programmer 20, and
patient programmer 22 may communicate via cables or a wireless
communication, as shown in FIG. 1. Clinician programmer 20 and
patient programmer 22 may, for example, communicate via wireless
communication with implantable stimulator 4 using RF telemetry
techniques known in the art or other standard communication
protocols such as, for example, Bluetooth.RTM.. Clinician
programmer 20 and patient programmer 22 also may communicate with
each other using any of a variety of wireless communication
techniques, such as RF communication according to the 802.11 or
Bluetooth specification sets, infrared communication, e.g.,
according to the IrDA standard, or other standard or proprietary
telemetry protocols. Each of clinician programmer 20 and patient
programmer 22 may include a transceiver to permit bi-directional
communication with implantable stimulator 4.
[0035] Generally, system 2 delivers stimulation therapy to patient
6 in the form of controlled current or voltage waveforms or
constant current or voltage pulses. The shapes of the pulses may
vary according to different design objectives. In the case of
current-based stimulation, implantable stimulator 4 regulates
current that is sourced or sunk by one or more electrodes, referred
to as regulated electrodes. In some examples, one of the electrodes
may be unregulated. In such configurations, either the housing
electrode or a lead electrode may be the unregulated electrode.
Alternatively, all active electrodes may be regulated, i.e.,
coupled to a current regulator such as a regulated current source
or sink.
[0036] A source current may refer to a current that flows out of an
electrode, e.g., from a regulated current source via a regulated
current path to surrounding tissue, or from a reference voltage via
an unregulated current path. A sink current may refer to a current
that flows into an electrode, e.g. from surrounding tissue and is
sunk by a regulated current sink via a regulated current path or by
a reference voltage via an unregulated current path. Regulated
source currents may sum to produce a greater overall source
current. Regulated sink currents may sum to produce a greater
overall sink current. Regulated source and regulated sink currents
may partially or entirely cancel one another, producing a net
difference in the form of a net source current or sink current in
the case or partial cancellation. An unregulated current path can
source or sink current approximately equal to this net
difference.
[0037] FIG. 2 is a conceptual diagram illustrating system 30 that
delivers stimulation therapy to spinal cord 38 of patient 36. Other
electrical stimulation systems may be configured to deliver
electrical stimulation to gastrointestinal organs, pelvic nerves or
muscle, peripheral nerves, or other stimulation sites. In the
example of FIG. 2, system 30 delivers stimulation therapy from
implantable stimulator 34 to spinal cord 38 via one or more
electrodes (not shown) carried by, i.e., located on, implantable
medical leads 32A and 32B (collectively "leads 32") as well as the
housing of implantable stimulator 34, e.g., housing electrode 37.
System 30 and, more particularly, implantable stimulator 34 may
operate in a manner similar to implantable stimulator 4 (FIG. 1).
That is, in a current-based example, implantable stimulator 34
delivers controlled current stimulation pulses or waveforms to
patient 36 via one or more regulated, stimulation electrodes.
Alternatively, implantable stimulator 34 may be configured to
deliver constant voltage pulses. As mentioned above, in some
examples, one of the electrodes may be unregulated.
[0038] In the example of FIG. 2, the distal ends of leads 32 carry
electrodes that are placed adjacent to the target tissue of spinal
cord 38. The proximal ends of leads 32 may be both electrically and
mechanically coupled to implantable stimulator 34 either directly
or indirectly via a lead extension and header. Alternatively, in
some examples, leads 32 may be implanted and coupled to an external
stimulator, e.g., through a percutaneous port. In additional
example implementations, stimulator 34 may be a leadless stimulator
with one or more arrays of electrodes arranged on a housing of the
stimulator rather than leads that extend from the housing.
Application of certain techniques will be described in this
disclosure with respect to implantable stimulator 34 and
implantable leads 32 having ring electrodes for purposes of
illustration. However, other types of electrodes may be used.
[0039] Stimulator 34 may be implanted in patient 36 at a location
minimally noticeable to the patient. For SCS, stimulator 34 may be
located in the lower abdomen, lower back, or other location to
secure the stimulator. Leads 32 are tunneled from stimulator 34
through tissue to reach the target tissue adjacent to spinal cord
38 for stimulation delivery. At the distal ends of leads 32 are one
or more electrodes (not shown) that transfer the stimulation pulses
from the lead to the tissue substantially simultaneously with
stimulation pulses. Some of the electrodes may be electrode pads on
a paddle lead, circular (i.e., ring) electrodes surrounding the
body of leads 32, conformable electrodes, cuff electrodes,
segmented electrodes, or any other type of electrodes capable of
forming unipolar, bipolar or multi-polar electrode
configurations.
[0040] The stimulation pulses may be delivered using various
electrode arrangements such as unipolar arrangements, bipolar
arrangements or multipolar arrangements. A unipolar stimulation
arrangement generally refers to the use of an anode on the housing
that sources current and one or more cathodes on one or more leads
that sink current. A bipolar stimulation arrangement generally
refers to the use of an anode on a lead that sources current and a
cathode on the same lead and/or another lead that sink current. A
multipolar stimulation arrangement generally refers to the use of
more than one anode on a lead that each source current and one or
more cathodes on the same lead or another lead that sink current,
or the use of one anode on a lead that sources current and multiple
cathodes on the same lead or another lead that sink current. A
hybrid stimulation arrangement that combines both unipolar and
bipolar electrode relationships may be referred to as an omnipolar
arrangement. In an omnipolar arrangement, an anode on the housing
may be used to deliver stimulation pulses substantially
simultaneously with at least one anode on a lead and at least one
cathode on a lead. In this case, for an omnipolar arrangement, at
least one anode on a lead and at least one anode on the housing can
be used simultaneously in combination with at least one cathode on
a lead. In other omnipolar arrangements, a cathode on the housing
may be used to deliver stimulation pulses substantially
simultaneously with at least one cathode on a lead and at least one
anode on a lead. In this alternative case, for an omnipolar
arrangement, at least one cathode on a lead and at least one
cathode on the housing can be used simultaneously in combination
with at least one anode on a lead. Any of the above electrode
arrangements, or other electrode arrangements, may be used to
deliver electrical stimulation in accordance with techniques
described in this disclosure.
[0041] Implantable stimulator 34 delivers stimulation to spinal
cord 38 to reduce the amount of pain perceived by patient 36. As
mentioned above, however, stimulators may be used with a variety of
different therapies, such as peripheral nerve stimulation (PNS),
peripheral nerve field stimulation (PNFS), deep brain stimulation
(DBS), cortical stimulation (CS), pelvic floor stimulation,
peripheral nerve stimulation, gastric stimulation, and the like.
The stimulation delivered by implantable stimulator 34 may take the
form of stimulation pulses or continuous stimulation waveforms, and
may be characterized by controlled current or voltage levels, as
well as programmed pulse widths and pulse rates in the case of
stimulation current pulses. Stimulation may be delivered via
selected combinations of electrodes located on one or both of leads
32 and on the housing. Stimulation of spinal cord 38 may, for
example, prevent pain signals from traveling through the spinal
cord and to the brain of the patient. Patient 34 perceives the
interruption of pain signals as a reduction in pain and, therefore,
efficacious therapy.
[0042] With reference to FIG. 2, a user, such as a clinician or
patient 36, may interact with a user interface of external
programmer 40 to program stimulator 34. Programming of stimulator
34 may refer generally to the generation and transfer of commands,
programs, or other information to control the operation of the
stimulator. For example, programmer 40 may transmit programs,
parameter adjustments, program selections, group selections, or
other information to control the operation of stimulator 34, e.g.,
by wireless telemetry.
[0043] In some cases, external programmer 40 may be characterized
as a physician or clinician programmer, such as clinician
programmer 20 (FIG. 1), if it is primarily intended for use by a
physician or clinician. In other cases, external programmer 40 may
be characterized as a patient programmer, such as patient
programmer 22 (FIG. 1), if it is primarily intended for use by a
patient. In general, a physician or clinician programmer may
support selection and generation of parameters and/or programs by a
clinician for use by stimulator 34, whereas a patient programmer
may support adjustment and selection of such parameters and/or
programs by a patient during ordinary use.
[0044] Whether programmer 40 is configured for clinician or patient
use, programmer 40 may communicate to implantable stimulator 34 or
any other computing device via wireless communication. Programmer
40, for example, may communicate via wireless communication with
implantable stimulator 34 using radio frequency (RF) telemetry
techniques known in the art or other communication standards such
as, for example, Bluetooth.RTM.. Programmer 40 may also communicate
with another programmer or computing device via a wired or wireless
connection using any of a variety of local wireless communication
techniques, such as RF communication according to the 802.11 or
Bluetooth.RTM. specification sets, infrared communication according
to the IRDA specification set, or other standard or proprietary
telemetry protocols. Programmer 40 may also communicate with
another programming or computing device via exchange of removable
media, such as magnetic or optical disks, or memory cards or
sticks. Further, programmer 40 may communicate with implantable
stimulator 34 and other programming devices via remote telemetry
techniques known in the art, communicating via a local area network
(LAN), wide area network (WAN), public switched telephone network
(PSTN), or cellular telephone network, for example.
[0045] In one example, programming of stimulator 34 of FIG. 2 may
also include graphically defining a desired stimulation field(s)
within zones on or adjacent to one or more leads or electrodes, and
generating, via a programmer, the current stimulation required to
create the stimulation field, e.g., as described with reference to
FIG. 1. Programming of stimulator 34 may also include translating
one or more user input stimulation zones into a set of electrodes
for delivering electrical stimulation therapy to a patient, and a
set of parameters such as pulse current amplitudes associated with
such electrodes. Programming may further include manipulating the
shape and position of the zone, including behaviors of the zone
while moving and when colliding with other zones or system
interlocks. As the stimulation zone is sized, moved, or shaped, the
programmer may automatically compute updated electrode selections
and parameters for delivery of stimulation indicated by the
stimulation zone. In one example, a user may import an image of the
anatomical region in which the leads are implanted and use the
imported image as background during programming. A graphical
representation of the leads used in programming for the specific
region may be over imposed on the image background and manipulated
such that the graphical representation of the leads corresponds to
the placement of the leads in the region.
[0046] Although the disclosure generally refers to implantable
stimulators for purposes of illustrations, techniques described in
this disclosure also may be used with other types of IMDs,
including implantable fluid delivery devices, such as insulin
pumps, intra-thecal drug delivery pumps, or other devices that
deliver medication or other fluids via one or more fluid delivery
elements such as catheters. Such devices may provide fluid delivery
therapy for chronic pain, diabetes, or any of a variety of other
disorders. In each case, the device may include one or more therapy
delivery elements such as one or more catheters implanted within a
therapy region. In some cases, a pump may be fully implantable or
may be an external device coupled to one or more percutaneously
implanted catheters that extend into a therapy region. Accordingly,
description of implantable stimulators is provided for purposes of
illustration and should not be considered limiting of the
techniques as broadly described in this disclosure.
[0047] FIG. 3 is a block diagram illustrating various components of
an example implantable stimulator 34. Although the components shown
in FIG. 3 are described in reference to implantable stimulator 34,
the components may also be included within implantable stimulator 4
shown in FIG. 1 and used within system 2. In the example of FIG. 3,
implantable stimulator 34 includes processor 50, memory 52, power
source 54, telemetry module 56, antenna 57, and a stimulation
generator 60. Implantable stimulator 34 is also shown in FIG. 3
coupled to electrodes 48A-Q (collectively "electrodes 48").
Electrodes 48A-48P are implantable and may be deployed on one or
more implantable leads. With respect to FIG. 1, lead segments 12A
and 12B may carry electrodes 48A-H and electrodes 48I-P,
respectively. In some cases, one or more additional electrodes may
be located on or within the housing of implantable stimulator 34,
e.g., to provide a common or ground electrode or a housing anode.
With respect to FIG. 2, leads 32A and 32B may carry electrodes
48A-H and electrodes 48I-P, respectively. In the examples of FIGS.
1 and 2, a lead or lead segment carries eight electrodes to provide
an 2.times.8 electrode configuration (two leads with 8 electrodes
each), providing a total of sixteen different electrodes. The leads
may be detachable from a housing associated with implantable
stimulator 34, or be fixed to such a housing.
[0048] In other examples, different electrode configurations
comprising a single lead, two leads, three leads, or more may be
provided. In addition, electrode counts on leads may vary and may
be the same or different from a lead to lead. Examples of other
configurations include one lead with eight electrodes (1.times.8),
one lead with 12 electrodes (1.times.12), one lead with 16
electrodes (1.times.16), two leads with four electrodes each
(2.times.4), three leads with four electrodes each (3.times.4),
three leads with eight electrodes each (3.times.8), three leads
with four, eight, and four electrodes, respectively (4-8-4), two
leads with 12 or 16 electrodes (2.times.12, 2.times.16), or other
configurations. In some examples, electrode configurations may
include percutaneous leads, surgical leads, or segmented leads with
different number of electrodes on each segment based on the therapy
applied by stimulator 34. Different electrodes are selected to form
electrode combinations. Polarities are assigned to the selected
electrodes to form electrode configurations.
[0049] Electrode 48Q represents one or more electrodes that may be
carried on a housing, i.e., can, of implantable stimulator 4.
Electrode 48Q may be configured as a regulated or unregulated
electrode for use in an electrode configuration with selected
regulated and/or unregulated electrodes among electrodes 48A-48P,
which may be located on a lead body of one or more leads, as
described above. Electrode 48Q may be formed together on a housing
that carries the electrode and houses the components of implantable
stimulator 4, such as stimulation generator 60, processor 50,
memory 52, telemetry module 56, and power source 54.
[0050] Housing electrode 48Q may be configured for use as an anode
to source current substantially simultaneously with current sourced
by one or more other electrodes 48A-48P to form a unipolar or
omnipolar electrode arrangement. By way of specific example, in an
omnipolar arrangement, electrodes 48A, 48B, and housing electrode
48Q each could be configured for use as anodes. Electrodes 48A, 48B
could deliver electrical stimulation current substantially
simultaneously with the electrical stimulation current delivered
via housing electrode 48Q. In this illustration, one or more
cathodes could be formed with other electrodes (e.g., any of
electrodes 48C-48P) on the leads to sink current sourced by anodes
48A, 48B and 48Q. Any of a variety of electrode arrangements such
as unipolar, bipolar, multipolar, or omnipolar arrangements may be
used to deliver stimulation. Accordingly, discussion of particular
arrangements are provided for purposes of illustration, which
should not be considered limiting of the techniques broadly
described in this disclosure.
[0051] Memory 52 may store instructions for execution by processor
50, stimulation therapy data, sensor data, and/or other information
regarding therapy for patient 6. Processor 50 may control
stimulation generator 60 to deliver stimulation according to a
selected one or more of a plurality of programs or program groups
stored in memory 52. Memory 52 may include any electronic data
storage media, such as random access memory (RAM), read-only memory
(ROM), electronically-erasable programmable ROM (EEPROM), flash
memory, or the like. Memory 52 may store program instructions that,
when executed by processor 50, cause the processor to perform
various functions ascribed to processor 50 and implantable
stimulator 4 in this disclosure.
[0052] In accordance with the techniques described in this
disclosure, information stored on the memory 52 may include
information regarding therapy that the patient 6 had previously
received or information regarding a current therapy. Storing such
information may be useful for subsequent treatments such that, for
example, a clinician may retrieve the stored information to
determine the therapy applied to the patient during a previous
session, in accordance with this disclosure. The information stored
in the memory 52 may be, for example, an image captured and
downloaded into the implantable stimulator 34 by a programmer, such
as clinician programmer 20 by wireless telemetry. As an example,
the image may be obtained during an in-clinic programming session,
and may show, for example, lead configuration and placement within
a therapy region targeted by one or more leads implanted in the
therapy region, in accordance with this disclosure. Images stored
in memory 52 may represent different regions to which therapy
should be delivered, and may be retrieved by the programmer to
combine with a representation of leads or lead groups to
effectively deliver therapy in subsequent sessions. As another
example, the image may be obtained during the current therapy
session. The therapy region could be any of several anatomical
regions of patient in which one or more leads may be implanted for
delivery of therapy, including the spinal cord, the occipital
region, the brain, the pelvic floor, the heart, the
gastrointestinal tract, one or more limbs, or the like. In one
example, other types of anatomical representations of therapy
regions may be utilized, in accordance with the techniques
described in this disclosure.
[0053] The programmer may obtain the image by capturing a
photograph of a hard copy or electronic display presenting an image
obtained by a diagnostic imaging device, such as a fluoroscopic
imaging or other x-ray imaging device, a magnetic resonance imaging
device, an ultrasonic imaging device, electrical impedance
topography, or other imaging devices. For example, the programmer
may include an integrated digital camera or may be coupled to a
digital camera, by a wired or wireless communication medium.
Alternatively, the programmer may obtain the image electronically
from an imaging device, a network storage server, a removable
storage medium such as Flash memory, or other devices. In each
case, the image may be stored at least temporarily on the
programmer, permitting viewing, manipulation, compression or
editing of the image. In some examples, a user may manipulate,
compress or edit the image to produce an image suitable or
desirable for downloading to the IMD for storage. Also, in some
examples, the IMD may store multiple images, e.g., from different
regions, different perspectives, or with different views, such as
different zoom factors, cropping, spatial resolution, image density
resolution or the like. In one example, the IMD may be used to
deliver therapy to multiple regions in the patient, and may store
images associated with the different therapy regions.
[0054] The image may be subsequently retrieved from the IMD, either
by a patient programmer or clinician programmer, or both, for any
of several reasons such as, for example, later viewing, or
subsequent programming and/or therapy delivery to the region
associated with the image. In some cases, storing the image in an
IMD may permit a clinician to retrieve and upload the image and
thereby view the image without the requirement for storage of the
image in the clinic or on the programmer. Rather, the clinician may
use a different programmer, or the patient may visit a different
clinic. In each case, the image may be accessed for review and
verification of lead configuration because it is conveniently
stored in the IMD, which is ordinarily with the patient. In some
cases, the image may alternatively or additionally be stored on a
patient programmer, which may be with the patient. However, storing
the image in the IMD may ensure that the image may be accessed by
an external programmer whenever the patient is present, e.g.,
whenever the patient visits a clinic for a programming session or
other evaluation.
[0055] Processor 50 may include one or more microprocessors,
digital signal processors (DSPs), application-specific integrated
circuits (ASICs), field-programmable gate arrays (FPGAs), or other
digital logic circuitry. Processor 50 controls operation of
implantable stimulator 34, e.g., controls stimulation generator 60
to deliver stimulation therapy according to a selected program or
group of programs retrieved from memory 52. For example, processor
50 may control stimulation generator 60 to deliver electrical
signals, e.g., as stimulation pulses or continuous waveforms, with
current amplitudes, pulse widths (if applicable), and rates
specified by one or more stimulation programs. Processor 50 may
also control stimulation generator 60 to selectively deliver the
stimulation via subsets of electrodes 48, also referred to as
electrode combinations, and with polarities specified by one or
more programs.
[0056] Upon selection of a particular program group, processor 50
may control stimulation generator 60 to deliver stimulation
according to the programs in the groups, e.g., simultaneously or on
a time-interleaved basis. A group may include a single program or
multiple programs. As mentioned previously, each program may
specify a set of stimulation parameters relating to a therapy
associated with the program, such as, for example, amplitude, pulse
width and pulse rate, if applicable. For a continuous waveform,
parameters may include such parameters as amplitude and frequency,
for example. In addition, each program may specify a particular
electrode combination for delivery of stimulation, and an electrode
configuration in terms of the polarities and regulated/unregulated
status of the electrodes. The electrode combination may specify
particular electrodes in a single array or multiple arrays, and on
a single lead or among multiple leads.
[0057] Stimulation generator 60 is electrically coupled to
electrodes 48A-P via conductors of the respective lead, such as
lead 12 in FIG. 1 or leads 32 in FIG. 2, in implementations in
which electrodes 48A-P are carried by, located on, leads.
Stimulation generator 60 may be electrically coupled to one or more
housing ("can") electrodes 48Q via an electrical conductor disposed
within the housing of implantable stimulator 4 (FIG. 1) or
implantable stimulator 34 (FIG. 3). A housing electrode 48Q may be
configured as a regulated or unregulated electrode to form an
electrode configuration in conjunction with one or more of
electrodes 48A-48P located on leads of the IMD. Housing electrode
48Q may be configured for use as an anode to source current
substantially simultaneously with one or more electrodes, e.g., any
of electrodes 48A-48P, on one or more leads configured for use as
anodes.
[0058] Stimulation generator 60 may include stimulation generation
circuitry to generate stimulation pulses or waveforms and circuitry
for switching stimulation across different electrode combinations,
e.g., in response to control by processor 50. Stimulation generator
60 produces an electrical stimulation signal in accordance with a
program based on control signals from processor 50.
[0059] For example, stimulation generator 60 may include a charging
circuit that selectively applies energy from power source 54 to a
capacitor module for generation and delivery of a supply voltage
for generation of stimulation signal. In addition to capacitors,
the capacitor module may include switches. In this manner, the
capacitor module may be configurable, e.g., based on signals from
processor 50, to store a desired voltage for delivery of
stimulation at a voltage or current amplitude specified by a
program. For delivery of stimulation pulses, switches within the
capacitor module may control the widths of the pulses based on
signals from processor 50.
[0060] Stimulation generator 60 may be configured to deliver
stimulation using one or more of electrodes 48A-P as stimulation
electrodes, e.g., anodes, while substantially simultaneously
delivering stimulation using housing electrode 48Q as a stimulation
electrode, e.g., anode. The anodes on the lead(s) and the housing
may be used to deliver stimulation in conjunction with one or more
cathodes on the lead(s). As one illustration, an electrode
combination selected for delivery of stimulation current may
comprise an anode on the IMD housing, and anode on a lead, and a
cathode on the same lead or a different lead. In other examples,
the electrode combination may include multiple anodes and/or
multiple cathodes on one or more leads in conjunction with at least
one anode on the IMD housing.
[0061] Telemetry module 56 may include a radio frequency (RF)
transceiver to permit bi-directional communication between
implantable stimulator 34 and each of clinician programmer 20 and
patient programmer 22. In one example, telemetry module 56 may
utilize other communication protocols and a corresponding
transceiver, for example, a Bluetooth.RTM. transceiver for
telemetry using the Bluetooth.RTM. protocol. Telemetry module 56
may include an antenna 57 that may take on a variety of forms. For
example, antenna 57 may be formed by a conductive coil or wire
embedded in a housing associated with medical device 4.
Alternatively, antenna 57 may be mounted on a circuit board
carrying other components of implantable stimulator 34 or take the
form of a circuit trace on the circuit board. In this way,
telemetry module 56 may permit communication with clinician
programmer 20 and patient programmer 22 in FIG. 1 or external
programmer 40 in FIG. 2, to receive, for example, new programs or
program groups, or adjustments to programs or program groups.
[0062] Telemetry module 56 may also permit communication with
clinician programmer 20 to send, for example, images of therapy
regions in the patient so that a programmer may set up and deliver
stimulation therapy accordingly. Telemetry module 56 may also
receive from programmer 20, for example, combined images
representing therapy regions with representation of lead placements
within the therapy regions for future access by a programmer, in
accordance with this disclosure.
[0063] Power source 54 may be a non-rechargeable primary cell
battery or a rechargeable battery and may be coupled to power
circuitry. However, the disclosure is not limited to examples in
which the power source is a battery. In another example, as an
example, power source 54 may comprise a supercapacitor. In some
examples, power source 54 may be rechargeable via induction or
ultrasonic energy transmission, and include an appropriate circuit
for recovering transcutaneously received energy. For example, power
source 54 may be coupled to a secondary coil and a rectifier
circuit for inductive energy transfer. In additional examples,
power source 54 may include a small rechargeable circuit and a
power generation circuit to produce the operating power. Recharging
may be accomplished through proximal inductive interaction between
an external charger and an inductive charging coil within
stimulator 4. In some examples, power requirements may be small
enough to allow stimulator 4 to utilize patient motion at least in
part and implement a kinetic energy-scavenging device to trickle
charge a rechargeable battery. A voltage regulator may generate one
or more regulated voltages using the battery power.
[0064] FIG. 4 is a functional block diagram illustrating various
components of an external programmer 40 for an implantable
stimulator 14. Although the components shown in FIG. 4 are
described in reference to external programmer 40, the components
may also be included within clinician programmer 20 or patient
programmer 22 shown in FIG. 1. As shown in FIG. 4, external
programmer 40 includes processor 53, memory 55, telemetry module
67, user interface 59, and power source 61. In general, processor
53 controls user interface 59, stores and retrieves data to and
from memory 55, and controls transmission of data with implantable
stimulator 34 through telemetry module 67. Processor 53 may take
the form of one or more microprocessors, controllers, DSPs, ASICS,
FPGAs, or equivalent discrete or integrated logic circuitry. The
functions attributed to processor 53 herein may be embodied as
software, firmware, hardware or any combination thereof.
[0065] Memory 55 may store instructions that cause processor 53 to
provide various aspects of the functionality ascribed to external
programmer 40 herein. Memory 55 may include any fixed or removable
magnetic, optical, or electrical media, such as RAM, ROM, CD-ROM,
magnetic disks, EEPROM, or the like. Memory 55 may also include a
removable memory portion that may be used to provide memory updates
or increases in memory capacities. A removable memory may also
allow patient data to be easily transferred to another computing
device, or to be removed before programmer 40 is used to program
therapy for another patient. Memory 55 may also store information
that controls operation of implantable stimulator 4, such as
therapy delivery values.
[0066] A clinician or patient 36 interacts with user interface 59
in order to, for example, manually select, change or modify
programs, e.g., by adjusting voltage or current amplitude,
adjusting pulse rate, adjusting pulse width, or selecting different
electrode combinations or configurations, and may provide efficacy
feedback or view stimulation data. User interface 59 may include a
screen and one or more input hard and/or soft key buttons that
allow external programmer 40 to receive input from a user. The
screen may be a liquid crystal display (LCD), plasma display, dot
matrix display, or touch screen. The input buttons may include a
touch pad, increase and decrease buttons, emergency shut off
button, and other input media needed to control the stimulation
therapy.
[0067] Using the techniques of this disclosure, a clinician or
patient 36 may graphically define one or more desired stimulation
regions using interface 59. Using user interface 59, a user may
view a combined image that includes an anatomical region of a
patient, e.g., in which one or more leads may be implanted, and a
graphical layer representing placement of one or more leads
implanted in the region. The image of the region may be obtained
following lead implant, and the placement of the leads within the
implant region may be visible in the image. At the time the image
is obtained, the user may add annotations regarding, for example,
the placement of the leads, the therapy stimulated by the leads,
and the patient. The image may be an image obtained via any of a
variety of imaging modalities such as a fluroscope or other x-ray
imaging device, an ultrasound imaging device, a magnetic resonance
imaging device, electrical impedance tomography, or other imaging
devices. The image may be obtained during a previous therapy
session or during the current therapy session, stored in the IMD,
and subsequently retrieved by a programmer. In one example, the
image may be stored in the patient programmer. In another example,
the image may be stored on a local or network drive, or a removable
memory device.
[0068] The graphical layer may be used to place a graphical
representation of the leads over the leads in the image, and the
user may manipulate the position and curvature of the graphical
representation of the leads to match that of the implanted leads.
The graphical representation of the lead may be used in a
programming procedure to program a desired electrical stimulation
therapy more effectively and accurately. For example, the graphical
representation of the lead, which is combined or overlaid with the
image of the anatomical region, may be used to select particular
electrodes forming an electrode combination, and assign current or
voltage amplitudes to the electrodes. In some cases, the programmer
may be configured to permit a user to define stimulation zone with
respect to a set of electrodes depicted by the graphical
representation of the lead, and permit the user to manipulate the
stimulation zone, e.g., by sizing, shaping or repositioning the
zone. As the zone is manipulated, the programmer may automatically
update the selection of electrodes associated with the zone, and
adjust stimulation intensity (e.g., pulse current or pulse voltage)
representing stimulation intensity contributions of the electrodes
(e.g., as source or sink electrodes) in forming a stimulation field
according to the stimulation zone. The combined image, including
the image of the anatomical region and the graphical image of the
lead representation, may be stored in the programmer or in the IMD
or on a removable storage device, e.g., for access by different
programmers in future clinical sessions to ensure regions defined
by the images are available for later evaluation.
[0069] Telemetry module 67 allows the transfer of data to and from
stimulator 34. Telemetry module 67 may communicate automatically
with stimulator 34 at a scheduled time or when the telemetry module
detects the proximity of the stimulator. Alternatively, telemetry
module 67 may communicate with stimulator 34 when signaled by a
user through user interface 59. To support RF communication,
telemetry module 44 may include appropriate electronic components,
such as amplifiers, filters, mixers, encoders, decoders, and the
like. In other examples, telemetry module 67 may employ other
communication standards such as, for example, Bluetooth.RTM. and
telemetry module 67 may include the appropriate Bluetooth.RTM.
components.
[0070] Programmer 40 may communicate wirelessly with implantable
stimulator 34 using, for example, RF communication or proximal
inductive interaction or other communication standards such as, for
example, Bluetooth.RTM.. This wireless communication is possible
through the use of telemetry module 67 which may be coupled to an
internal antenna or an external antenna. Telemetry module 67 may be
similar to telemetry module 57 of implantable stimulator 34. In
accordance with this disclosure, programmer 40 may communicate with
stimulator 34, via telemetry module 56 to retrieve information such
as, for example, images of regions with lead placements and
previously delivered therapy, which may be stored in memory 52 for
viewing and/or manipulation by a user via user interface 59.
[0071] Programmer 40 may also be configured to communicate with
another computing device via wireless communication techniques, or
direct communication through a wired, e.g., network, connection.
Examples of local wireless communication techniques that may be
employed to facilitate communication between programmer 24 and
another computing device include RF communication based on the
802.11 or Bluetooth.RTM. specification sets, infrared
communication, e.g., based on the IrDA standard.
[0072] Power source 61 delivers operating power to the components
of programmer 40. Power source 61 may be a rechargeable battery,
such as a lithium ion or nickel metal hydride battery. Other
rechargeable or conventional batteries may also be used. In some
cases, external programmer 40 may be used when coupled to an
alternating current (AC) outlet, i.e., AC line power, either
directly or via an AC/DC adapter. Power source 61 may include
circuitry to monitor power remaining within a battery. In this
manner, user interface 59 may provide a current battery level
indicator or low battery level indicator when the battery needs to
be replaced or recharged. In some cases, power source 61 may be
capable of estimating the remaining time of operation using the
current battery.
[0073] FIG. 5 is a block diagram illustrating various components of
an example stimulation generator 60A. Stimulation generator 60A may
be used with an implantable stimulator, e.g., to perform the
functions of stimulation generator 60 as described with reference
to FIGS. 1-3. Although described with respect to implantable
stimulator 4, stimulation generator 60A may also be used for
implantable stimulator 34, or other types of stimulators. In the
example of FIG. 5, stimulation generator 60A is selectively, e.g.,
based on a signal from processor 50 (FIG. 3), configured to deliver
constant current stimulation pulses to patient 6 via various
electrode combinations. However, the disclosure is not limited to
examples in which regulated current pulses are delivered. In other
examples, stimulation generator 60A may provide continuous,
regulated current waveforms, rather than regulated current pulses.
In still other examples, stimulation generator 60A may deliver
combinations of continuous waveforms and pulses, or selectively
deliver either continuous waveforms or pulses. Stimulation
generator 60A may generate either constant current-based or
constant voltage-based stimulation in the form of pulses or
continuous waveforms. In yet other examples, stimulation generator
60A may user a voltage regulator instead of a current
regulator.
[0074] In the example illustrated in FIG. 5, stimulation generator
60A includes stimulation control module 62, reference voltage
source 64, switch array 66, and current regulator array 68.
Reference voltage source 64 may provide operating power to current
regulator array 68, and may include a regulated voltage that sets
the level of the reference voltage. As shown in FIG. 5, reference
voltage source 64 may be coupled to provide operating power for the
current regulator array 68 and provide a reference voltage for
connection to electrodes 48A-48Q for an unregulated mode of
electrode operation. In other examples, however, the voltage level
of the reference voltage and the operating voltage level provided
to regulated current source array 68 may be different.
[0075] Stimulation control module 62 forms a stimulation controller
that controls switch array 66 and current regulator array 68 to
deliver stimulation via electrodes 48A-48Q. Stimulation control
module 62 may include one or more microprocessors,
microcontrollers, digital signal processors (DSPs),
application-specific integrated circuits (ASICs),
field-programmable gate arrays (FPGAs), or other integrated or
discrete logic circuitry. In operation, stimulation control module
62 may control delivery of electrical stimulation according to one
or more programs that may specify stimulation parameters such as
electrode combination, electrode polarity, stimulation current
amplitude, pulse rate, and/or pulse width as well as the percentage
of source current distributed among or contributed by a housing
anode and one or more lead anodes on one or more leads, and the
percentage of sink current sunk by one or more cathodes. Programs
may be defined by a user via an external controller and transferred
to an implantable stimulator 4 or 34 for use by stimulation control
module 62.
[0076] Current regulator array 68 includes a plurality of regulated
current sources or sinks Again, a current regulator may function as
either a current source or sink, or be selectively configured to
operate as either a source or a sink. For convenience, however, the
term "current regulator" may be used in some instances to refer to
either a source or sink. Hence, each of the current regulators in
current regulator array 68 may operate as a regulated current
source that delivers stimulation via a corresponding one of
electrodes 48A-Q or a regulated current sink that receives current
from a corresponding one of electrodes 48A-Q, where electrodes
48A-48Q may be provided on leads, on a stimulator housing, on a
leadless stimulator, or in other arrangements. In general,
electrodes 48A-48Q may be referred to below as electrodes 48 for
conciseness.
[0077] Each switch of switch array 66 couples a corresponding one
of electrodes 48 to either a corresponding bidirectional current
regulator of current regulator array 68 or to reference voltage 64.
In some examples, stimulation control module 62 selectively opens
and closes switches in switch array 66 to configure a housing
electrode, e.g., electrode 48Q, and one or more of electrodes
48A-48P on one or more leads as regulated electrodes by connection
to regulated current sources or sinks in current regulator array
68. In other examples, stimulation control module 62 may
selectively open and close switches in switch array 66 to configure
either the housing electrode, e.g., electrode 48Q, or an electrode
on the lead as an unregulated electrode by connection to reference
voltage 64. In addition, stimulation control module 62 may
selectively control individual regulated current sources or sinks
in current regulator array 68 to deliver stimulation current pulses
to the selected electrodes.
[0078] Reference voltage 64 may be a high or low voltage supplied
by a regulated power source, depending on whether an electrode is
programmed to be an unregulated source (high voltage rail) or
unregulated sink (low voltage rail). Hence, reference voltage 64
may produce high and low reference voltages for selective coupling
to unregulated, reference electrodes as needed given the selected
electrode configuration. A regulated power source may produce one
or more regulated voltage levels for use as reference voltage 64
and for use as a power rail for current regulator array 68. Again,
although the same reference voltage 64 is coupled to current
regulator array 68 in FIG. 5, different voltage levels could be
used for the reference voltage coupled to switch array 66 and the
operating voltage level provided to the regulated current source
array. A regulated power source may generate the regulated voltages
from voltages provided by a power source 54 (FIG. 3), such as a
battery.
[0079] Stimulation control module 62 controls the operation of
switch array 66 to produce electrode configurations defined by
different stimulation programs. In some cases, the switches of
switch array 66 may be metal-oxide-semiconductor
field-effect-transistors (MOSFETs) or other circuit components used
for switching electronic signals. The switches of switch array 66
may be designed to carry an amount of unregulated current that may
be coupled to a corresponding electrode through an unregulated
current path associated with reference voltage 64. As previously
described, in some examples, two or more regulated stimulation
electrodes 48 may be intentionally programmed to deliver different
amounts of current such that the regulated electrodes produce an
unbalanced current distribution.
[0080] To provide individual control of electrodes 48 as either
regulated electrodes or as unregulated, reference electrodes,
stimulation control module 62 controls operation of switch array
66, and current regulator array 68. When stimulation is delivered
to patient 6, for the example of current pulses, stimulation
control module 62 controls switch array 66 to couple selected
stimulation electrodes for a desired electrode combination to
respective current regulators of current regulator array 68 or to
reference voltage 64, as needed. Stimulation control module 62
controls the regulated bidirectional current sources of current
regulator array 68 coupled to regulated electrodes to source or
sink specified amounts of current. For example, stimulation control
module 62 may control selected current sources or sinks to on a
pulse-by-pulse basis to deliver current pulses to corresponding
electrodes.
[0081] Stimulation control module 62 also deactivates the regulated
bidirectional current regulators of current regulator array 68 tied
to inactive electrodes, i.e., electrodes that are not active as
regulated electrodes in a given electrode configuration. Each
regulated bidirectional current regulator of current regulator
array 68 may include an internal enable switch controlled by
stimulation control module 62 that disconnects regulated power
source 64 from the current regulator or otherwise disables the
current source when the corresponding electrode is not used as a
regulated electrode to deliver stimulation.
[0082] FIGS. 6A-6L illustrate an exemplary sequence of programmer
screens, in accordance with this disclosure. FIGS. 6A-6L each show
an exemplary screen shot 600 of a display on the user interface 59
on a programmer 40 as described in this disclosure. In one example,
programmer 40 may be a clinician programmer. FIGS. 6A-6L are
discussed in the context of a patient receiving spinal cord
stimulation therapy as an illustrative example. A programmer, e.g.,
programmer 40, may receive user input via the user interface 59 to
set up leads and parameters that define one or more stimulation
programs for delivering therapy to a patient. A stimulation program
may be delivered by an implantable stimulator individually or in
combination with other programs, e.g., on a time-interleaved basis.
A program may define an electrode combination, including a selected
set of electrodes for delivery of stimulation and polarities of
such electrodes, pulse current or pulse voltage amplitudes
delivered by respective electrodes, pulse width and pulse rate. The
user may set up a profile for the session and the patient, and
proceed to configure placement of the leads.
[0083] To provide an accurate representation of implanted leads for
spinal cord stimulation, the user may select which leads will be
programmed with therapy. In this example, there are up to 4 leads
from which a user may select. However, in other examples there may
be more or less leads available to the user from which to select.
FIG. 6A illustrates a lead set up screen where the user is prompted
to indicate whether all the leads, for the given number of leads
implanted or being trialed, will be placed in the same region
and/or programmed together by indicating "Yes" or "No" (601). If
the user selects that all the leads will be placed in the same
region and/or programmed together, i.e., the user selects "Yes,"
the lead set up screen may prompt the user to enter a name for the
lead region to which the leads are assigned (603), as shown in FIG.
6B. Otherwise, as shown in FIG. 6J, the user may respond with "No"
(651), indicating that leads will be assigned to different lead
regions and/or programmed separately. As a result, the lead set up
screen may prompt the user to enter a name for each lead region
(653) (in this example, 4 regions, but may be more or less regions)
and to select the leads (655) that will be programmed for each of
the lead regions (in this example, 4 leads per region, but may be
more or less leads). A lead region may be, for example, such entity
as "lumbar spine" or "epidural thoracic." The user may assign
implanted leads to one or more regions, where the regions represent
the anatomical implant location of the leads associated with the
regions. In one example, where different leads are selected for
different regions, the user may view and/or program each region
where only the leads associated with a selected region are viewed
and/or programmed. In one example, the user may assign the case
electrodes to one or more regions, either alone or in combination
with the implanted leads.
[0084] After the leads are organized, the region where they are
implanted may be named (605 and 653) by the user (epidural
thoracic, etc.), as shown in FIG. 6C and 6J. When the user enters a
name for the lead region or selects one from a checklist or
drop-down menu, the "Done" button (607) may be highlighted allowing
the user to select it and go on to the next screen, as shown in
FIG. 6C. Referring to FIG. 6J, when the user enters a name for a
lead region and selects the leads for that region, the "Done"
button may be highlighted (not shown highlighted as no leads have
been selected) allowing the user to move on to the next lead region
to name it and select the corresponding leads, and so forth, until
all the lead regions (in this example 4 lead regions, which may be
more or less in other examples) and named and corresponding leads
are selected for each lead region.
[0085] Once the lead regions are named, a representation of the
leads to be programmed for that region may be shown on the screen.
Referring to FIG. 6D, the representation of two leads (609), each
with 8 electrodes may be shown on the screen, because the user
selected to program them all together (in this example two leads).
Alternatively, referring to FIG. 6K, if multiple lead regions are
programmed, representation of the leads (657) for each lead region
may be shown on the screen. In the multiple lead region scenario of
FIG. 6K, for example, for the lead region named "Non-Epidural
Spine," the user selected lead 1, which has four electrodes in this
example, to be programmed for this lead region, and therefore, only
lead 1 (657) is displayed on the screen for the lead region
"Non-Epidural Spine." Each of the remaining lead regions, e.g.,
"Occipital Right" (659), "Occipital Left" (661), and "Non-Epidural
Torso" (663), has its own tab, and when the tab for a lead region
is selected, the screen will display the leads the user selected
(in screen of FIG. 6J) for that region. The discussion at this
point will deal with the screens for the example where all leads
were selected to be programmed for one region and together, but it
should be noted that the same discussion can be applied to the case
of multiple regions.
[0086] Referring again to FIG. 6D, the graphical representation of
the leads (609) may be displayed on the screen, and the user may be
provided with more options from which to select. The user may be
presented with an option to import an image for the lead region
being programmed (611). The image may be for example a fluoroscopic
image of the region in which therapy is to be applied. A button
(611) labeled "Import Fluoro Image" appears on the display as shown
in FIG. 6D, which the user may select if the user opts to import a
fluoroscopic image of the leads assigned to the region for which
therapy is being programmed. In another example, the display may
also have a "Start Camera" button (not shown), which may, upon
selection by the user, display an image acquired by the camera,
which the user may select to use as the background image by
clicking a button (665) labeled "Take Picture," as shown in FIG.
6L, as an alternative for importing a previously-acquired image.
Therefore, a user may have an option to either use the camera or
import a previously-acquired image, as shown in FIG. 6L. One or
more examples of acquiring and storing a fluoroscopic image of a
therapy region in a patient may be described in co-pending United
States Patent Application, to Davis et al., titled "STORING IMAGE
OF THERAPY REGION IN IMPLANTABLE MEDICAL DEVICE," filed the same
day as the present application, and bearing Attorney Docket No.
1023-894US01, the entire content of which is incorporated herein by
reference.
[0087] The display screen may also present options to the user to
manipulate the positions or the representation of the leads 609. In
the example of FIG. 6D, the user may move a lead by tapping and
holding on the lead and dragging it, or the user may rotate or
curve a lead by tapping and holding on an anchor point and dragging
as indicated by the instructions (629) provided to the user on the
screen. The user may also swap the lead orientation by selecting
the corresponding function button (613). The user may also
manipulate the leads further by bending, resizing, and shaping the
graphical representation of the leads or portions of the leads to
achieve a better match between the graphical leads and the image of
the leads in the anatomical background image. In one example, the
user may select starting and ending points of the leads in the
image (e.g., to match distal and proximal electrode locations in
the image), and the programmer may automatically draw the graphical
representation of the leads between the two points. The display may
also show the electrode configuration (615), showing how the leads
are inserted. In one example, an option (617) may be displayed to
"Check Lead Insertion" to check that the leads are inserted
correctly. The display may also present the user with the ability
to manipulate the fluoroscopic image, as shown on the left side of
the screen. However, the fluoroscopic image tools may not be
highlighted until a fluoroscopic image is actually imported (see
FIG. 6D, where user has not imported an image yet, and the
fluoroscopic image tools are grayed out (621)).
[0088] Referring to FIG. 6E, the user may select to check the lead
insertion by selecting the "Check Lead Insertion" button (623) when
it is available (i.e., not grayed out). For example, the "Check
Lead Insertion" button (623) may be unavailable if certain
information is missing, e.g., assignment of electrode numbers to
leads, or if lead insertion was previously checked, no problems
were detected, and no other changes were detected. In one example,
lead insertion may allow the user to ensure that the lead is
correctly inserted into the header. The lead insertion check may
be, for example, an impedance measurement between pairs of
electrodes along the lead (e.g., impedance from electrode 0 to
electrode 1, impedance from electrode 1 to electrode 2, etc.). The
"Check Lead Insertion" button (623) may be grayed out during the
measurement. Referring to FIG. 6F, the display may indicate to the
user the results of checking the insertion of the leads, and if, as
in this case, there are no issues with the insertion of either
lead, next to each lead under "Lead Configuration" on the right
side of the screen the text "Inserted OK" (625) may be displayed.
In one example, there may be issues with lead insertion, and the
user interface may display "NOT OK," which may signal to the user
to manipulate the lead or remove the lead and reinsert it into the
header and check again. In one example, the lead insertion check
may result in a "NOT OK" if certain issues exist such as, for
example, no lead is present (e.g., the impedance for all electrodes
is out of range), the lead partially inserted (e.g., the impedance
of only a subset of electrodes is in range, indicating partial
insertion and the impedance of the remaining leads is out of
range), the lead is fully inserted but poor connections exist
(e.g., the lead is fully inserted, but the impedance of one or more
electrodes is out of range), possible fluid in connector (e.g., the
impedance of one or more electrodes is low, indicating shorts
exist).
[0089] Referring to FIG. 6G, the user may then select to import a
fluoroscopic image, and the image (627) may be imported. The
representation of the leads (629) may be superimposed on the
fluoroscopic image (627) of the leads. While it is not shown, a
similar screen may be displayed for each of the regions when
multiple regions are defined, and the user may import a
fluoroscopic image to one or more regions, by clicking on the tab
for the region (see FIG. 6K) and clicking on the "Import Fluoro
Image" for that region.
[0090] In one example, the representation of the leads (609) may
not be initially aligned with the leads in the fluoroscopic image
(629). To get the representation of the leads (609) to more
accurately align with leads in the fluoroscopic image (627), the
representation of the leads (609) may be scaled, stretched, bent,
moved, or rotated to match the actual leads shown in the background
imported image. In some examples, the leads may have curvature
added to them to match the imported fluoroscopic image. For
example, by moving selected anchor points along the lead, the user
may move a portion of the lead relative to other portions of the
lead to introduce a desired bend, such as a bend that more
precisely matches a bend in the actual implanted lead shown in the
background image. In addition, the fluoroscopic image (627) may be
moved, zoomed, or manipulated to match a generic drawing of the
lead, and that can be done once the image is imported and the
"fluoro tools" (631) is highlighted as shown in FIG. 6G. The
fluoroscopic image (627) may also be annotated, e.g., by text
notes, by clicking the "Annotate" button (633). As can be seen in
the example image in FIG. 6G, the region in this image includes the
T6, T7 vertebrae. Each of leads 1 and 2 are 8-electrode leads. As
shown in FIG. 6J and 6K, however, the leads may be 4-electrode
leads, or other n-electrode leads in other examples. In one
example, when the user selects one of the regions, the image for
that region and the graphical representation of the leads assigned
to that region may be displayed on the user interface.
[0091] In one example, the user interface may display the image and
graphical representation of leads in 2D. In this example, the user
interface may display the same region and the corresponding
graphical representation of leads implanted in the region in 2D
from different perspectives corresponding to different angles or
cross sections, as the implanted leads may curve in more than one
direction spatially, and allow the user to manipulate the graphical
representation of leads for each perspective. In another example,
the user interface may display the image and graphical
representation of leads in 3D. In this example, the user interface
may display the region and the corresponding graphical
representation of leads implanted in the region in 3D, and may
allow the user to rotate and manipulate the image and the graphical
representation in all directions.
[0092] Referring to FIG. 6H, the user may select to annotate the
fluoroscopic image by clicking the button (633) "Annotate." The
display may then instruct the user to annotate the image by
"tapping on image to insert annotation." The user may manipulate
the fluoroscopic image (627) and the representation of the leads
(609) so that they align. The user may then scale fluoroscopic
image (627) and the representation of the leads (609) together or
separately. To more easily view the leads, the leads may be drawn
as transparent with color outlines. The transparency and color
outline allow the user to more easily align with the underlying
fluoroscopic image layer.
[0093] After the leads and fluoroscopic image have been manipulated
to match for a given region, the process may be repeated for all
lead regions (if multiple regions are programmed). The fluoroscopic
image may be compressed and stored in the device, by selecting the
button (635) labeled "Program" on the screen, as shown in FIG. 6I.
Selecting "program" may program all the changes to the device. The
display may also present the user with other options like "Tools"
and "Summary" in addition to "Programming." Subsequently, the
creation of therapy may occur (per lead region) on the final lead
representation of the leads with the fluoroscopic image as
background.
[0094] Each process described for the example of assigning all the
leads to one image, may be used with each of the different regions
(for example, the four as defined in FIG. 6K). When multiple
regions are defined, multiple fluoroscopic images may be linked to
corresponding multiple lead electrode images and locations, and
attributes related to the leads and the images may be linked
thereto, and the combination of the images, leads, and attributes
may be programmed and stored on medical devices, using the
techniques described herein. Each of the images may be associated
with an anatomical region, or with different perspectives of the
same region, for example. Additionally, a lead may be programmed to
provide therapy associated with more than one region. In one
example, the user may assign and program the case electrodes for
certain anatomical regions in the same manner the user assigns and
programs implanted leads.
[0095] FIG. 7 is a flow diagram illustrating exemplary operation of
a programmer to create, assign, and manipulate leads in different
anatomical regions in a patient, in accordance with this
disclosure. A programmer, e.g., programmer 40, receives user input
via the user interface 59 to set up leads (700) for use in defining
one or more stimulation programs. A stimulation program may be
delivered by an implantable stimulator individually or in
combination with other programs, e.g., on a time-interleaved basis.
A program may define an electrode combination, including a selected
set of electrodes for delivery of stimulation and polarities of
such electrodes, pulse current or pulse voltage amplitudes
delivered by respective electrodes, pulse width and pulse rate. The
user may set up a profile for the session and the patient, and
proceed to configure placement of the leads. The user interface may
show a screen as shown in FIG. 6A, and may inquire as to whether
all the leads will be placed in the same region and/or programmed
together.
[0096] The user may then select whether the leads will all be
placed in the same region and/or programmed together (705). The
programmer will then indicate that a lead region is to be created,
if the user selects to have all leads placed in the same region, as
shown in FIG. 6B. Alternatively, if the user selects NO in response
to whether all leads will be placed in the same region, the
programmer will display multiple lead regions, as shown in FIG. 6J.
In one example, when the user indicates a selection for multiple
regions, the programmer may display a selection for the user to
indicate the number of lead regions, from which the user may select
two or more regions. In the example of FIG. 6J, there may be four
regions to define for the current therapy session for the specified
user. In another example, the programmer may automatically show the
regions associated with the current patient, and the user may be
able to change the number of regions if a therapy region is no
longer needed or to add a new region.
[0097] As a result, in either case, at least one region is created,
where lead regions may correspond to anatomical regions, where each
region is to receive stimulation therapy corresponding to a
symptom, disorder or disease or other problem associated with the
specified region for the specified patient. For each lead region,
the user may assign leads, which may be chronically implanted or
percutaneously implanted for testing before chronic implantation,
to deliver therapy to the corresponding region. For each group of
one or more leads assigned to a lead region, the user may select
which leads will be programmed together and which will be
programmed separately. For example, for one region, the most
effective therapy may be to group all the leads together and
program them to deliver therapy as a group. For another region, the
most effective therapy may be to group only a portion of the leads
and program them together, and program the rest of the leads either
separately or as a separate group. For yet another region, the most
effective therapy may be to program each lead separately.
[0098] The user may then label or name the region (710). The
regions may be for example labeled according to the anatomical name
of the region, such as, for example, "lumbar spine" or "cervical
spine," as shown in FIG. 6C and FIG. 6K. The regions may also be
named by the user using text entry, or may be selected from a drop
down menu that contains generic names for regions (e.g., region 1,
region 2, etc.), default names associated with commonly targeted
regions e.g., lumbar spine, cervical spine, epidural thoracic,
non-epidural spine, occipital left, occipital right, non-epidural
torso, or the like), or regions associated with the patient
receiving the treatment where he had previously received treatment.
In another example, the names of the regions may be auto-populated
based on entries previously made on the programmer or for the
patient.
[0099] A representation of the leads may be displayed on the
interface, as shown in FIG. 6D, and the user may be given the
option to import a stored or captured image representing the region
where therapy is to be delivered. Alternatively, if the user elects
to not import an image of the region or if such an image is not
available, the leads may be configured using a default
position/placement. In an example, a default position for the leads
may be the vertical position for a region that the user may leave
unnamed, for example, if the user elects to name a region "Region
1," the leads may be displayed vertically by default. In another
example, if the user elects to name the region, depending on the
name, the default position for the leads may be a typical lead
positioning for delivering therapy to that region, but can be
altered by the user. The default position/placement of the leads
may be useful in application where quick programming is desirable,
for example, in an operating room. The user may also be capable of
checking lead insertion to ensure availability of the leads before
proceeding with therapy, as shown in FIG. 6E. The interface may
then indicate the results of checking the lead insertion. If there
are no issues with the lead insertion, the user interface may
indicate that the insertion of each lead is OK, as shown in FIG.
6F. If, for example, there are problems with lead insertion, i.e.,
the insertion of the leads is not OK (e.g., no lead is inserted in
the header, the lead is partially inserted, lead fully inserted by
poor connections exist, or possible fluid in connector), the
interface may indicate to the user that the leads are not correctly
inserted, and may display instructions on how to correct the issue,
e.g., re-insert the lead, confirm the correct model numbers for the
leads, or the like.
[0100] The user may opt to import an image representing the region
to which therapy will be applied (715). The image of a region may
be a fluoroscopic image of the region, as shown in FIG. 6G. In
other examples, the image of the region may be a graphical
representation of the region, e.g., an anatomical image of the
spinal cord. Importing an image may also be done by acquiring the
image at the time of the programming, with a camera on or connected
to the programmer, and may appear right away on the screen, as
shown in FIG. 6L. In some examples, the image may be a video image
of the region or a series of still images showing change over time.
Each region defined by the user may be represented by a separate
image. The image for each region may be an image captured by the
current user of the programmer, may be acquired/captured right at
that time with a camera on or connected to the programmer, or may
be a stored image, which had been captured during a previous
session and stored in the implanted medical device. For example,
during a previous session, an image of the lead placement in the
region receiving therapy may have been obtained by the programmer,
manipulated by the user, and downloaded into the implanted device
for subsequent treatments. The manipulation may involve, for
example, compressing and cropping the image to accommodate limited
storage capacity on the medical device, adding information
regarding the attributes of the leads, adding information regarding
the image compression and resizing to enable reconstructing the
image, and adding information regarding the therapy received and
the location of the clinic, for example, where the previous
treatment was received, among other information. The user may also
use an annotation tool (FIG. 6H) to add annotations to the
graphical representation of the lead or leads and the image. For
example, the user may add information regarding the configuration
or placement of certain leads or the stimulations parameters
associated with electrodes on the leads, etc. In some cases, an
image may include annotations with respect to a lead revision
history, i.e., a history of lead modifications or replacements.
[0101] The user may manipulate the leads on the imported image and
may manipulate the imported images themselves using the user
interface (720). The representations of the leads may be
manipulated by the user to match the regions in which they are
grouped. Manipulations of the leads representations may be such
functions as scaling, stretching, moving, bending, and rotating,
for example. Typically, the user may select a lead, e.g., from a
menu based on lead type and configuration. The programmer then may
add the selected lead to the image displayed by the user interface.
The user may reposition the lead, e.g., by dragging the lead or a
portion of the lead with a pointing tool such as a stylus, mouse,
or the like. In some cases, the user may drag the graphical lead
representation, i.e., the drawn lead, to a position that
approximately corresponds to a position of an actually-implanted
corresponding lead in the image. The lead representation may
initially be straight. However, the actual implanted lead or leads
shown in the image may be curved, bent or have some other
non-linear shape. The representation of the leads on the user
interface 59 of the programmer 40 may be also manipulated into a
curved, bent, or other nonlinear shape to match the imported image
of the region in which the lead is to deliver stimulation therapy.
For example, the lead may have control points that the user can
click and drag to change the lead from a straight shape to a curved
shape. For example, a lead may have multiple control points such
that the user may manipulate the lead to have multiple curves. In
one example, a lead may have control points on all or a subset of
the electrodes associated with the lead. The user may also
manipulate the imported images by moving or rotating the image or
zooming, for example. The user may manipulate both the drawn
graphical representations of the leads and the imported image until
the desired placement is achieved, e.g., a placement in which the
graphical lead representations are generally aligned with the
corresponding imaged leads. In one example, the drawn leads may be
represented with a transparent or semi-transparent drawing, so that
the user can more easily and accurately align the drawn leads onto
the imported image. The orientation of leads in an image may also
be automatically detected, and the representation of the drawn
leads may be automatically modified and moved to match the leads in
the image, saving effort by the user. In one example, the match may
be verified visually by the user. In another example, the match may
be performed automatically by image processing techniques that
identify the leads in the image based on their contrast relative to
the background. One or more examples of characterizing leads using
image analysis may be described in U.S. patent application Ser. No.
12/359,261 titled "AUTOMATED PROGRAMMING OF ELECTRICAL STIMULATION
ELECTRODES USING POST-IMPLANT IMAGING," filed on Jan. 23, 2009, and
U.S. application Ser. No. 12/359,264 titled "ELECTRODE-TO-LEAD
ASSOCIATION USING POST-IMPLANT IMAGING," filed on Jan. 23, 2009,
the entire contents of each being incorporated herein by
reference.
[0102] In one example, the user interface may display the image and
graphical representation of leads in 2D. In this example, the user
interface may display the same region and the corresponding
graphical representation of leads implanted in the region in 2D
from different perspectives corresponding to different angles or
cross sections, as the implanted leads may curve in more than one
direction spatially, and allow the user to manipulate the graphical
representation of leads for each perspective. In this example, the
user may manipulate the leads in the different 2D images
corresponding to different perspectives of the same lead
arrangement, and the programmer may reconstruct a 3D using the
different 2D manipulated images. In another example, the user
interface may display the image and graphical representation of
leads in 3D. In this example, the user interface may display the
region and the corresponding graphical representation of leads
implanted in the region in 3D, and may allow the user to rotate and
manipulate the image and the graphical representation in all
directions.
[0103] After a match is completed between the drawn lead layer and
the imported image of the corresponding region, including the image
leads, the combined image may be compressed and stored for future
use (725). The combined image may be imported into and stored on
the implanted device for future use by a clinician. A copy of the
combined image may be also stored on the patient programmer, a
memory device associated with the clinic where patient is receiving
therapy, or a network drive, for example. The combined image may
then be available for other functions by the programmer (FIG. 6I)
such as, for example, delivering therapy to the region through the
leads placed in that region.
[0104] The process of drawing and matching the leads onto the
imported image, then compressing and storing the image may be
repeated for each region defined by the user. Compression of the
image may be accomplished by using such techniques as cropping,
gray-scaling, and reducing intensity/contrast, for example, in
different combinations to provide maximum compression.
[0105] Subsequently, the creation of therapy programs may occur
(per lead region) on the final lead representation of the leads
with the image as background, "not shown," or as a sidebar. In
other words, the image that was used to position the drawn leads
can be displayed with the drawn leads or hidden, or represented in
a sidebar region to the side (or above or below) of the graphical
image showing the drawn leads. In another example, the user may
elect to "hide the leads" and it would appear as though the user is
programming directly on the background image. For creation of a
therapy program, the user may select electrodes on the graphical
drawn leads and assign parameters such as polarity, amplitude,
pulse width, and pulse rate. Alternatively, the user may draw
stimulation zones within the region, over the leads, and assign
stimulation polarities (cathodic or anodic) and stimulation
intensities to the leads. In one case, the programmer may
automatically compute pertinent stimulation amplitudes, such as
pulse current levels, for the electrodes associated with a
stimulation zone. The electrodes associated with a stimulation zone
may be electrodes that fall partially or entirely within a
stimulation zone drawn by the user. The stimulation zone may be a
polygon or some other regular or irregular shape. The pulse current
levels assigned to electrodes in such a zone may be determined
based on relative contributions of the electrodes, according to
their positions within the stimulation zone. In another example,
the leads may be programmed by selecting leads or parts of leads
and defining programming parameters for the selected leads or parts
of leads. The parameters may be, for example, amplitude, pulse
rate, pulse width, etc.
[0106] As shown in the figures, when multiple regions are created,
the same leads may be used for all regions, and therefore, one lead
may be programmed to provide therapy for more than one region. For
example, a lead may be placed near the spine, but may be used to
stimulate two regions. For example, one lead may be placed in the
epidural spine and another lead may be placed subcutaneously near
the epidural lead, one lead region may include both leads together,
with a second region including only the epidural lead, and a third
lead region utilizing only the subcutaneous lead. The leads may be
also divided into groups that are implanted and peripheral, and a
combination of implanted and peripheral leads may be used to
deliver therapy to one region. In one example, the case electrodes
may be also programmed to provide therapy to certain regions, alone
or along with other leads (implanted and/or subcutaneous). Each
lead may also be programmed so that different criteria, e.g.,
amplitude, impedance, etc., may be applied to different regions or
to different lead groups within a region. The programmer may be
capable of providing measurements of inter-region and intra-region
signals, to determine the effects of cross signals on the
performance of a lead group in a specific region. In one example,
the programmer may instruct the IMD to perform measurements, e.g.,
voltage and current measurements, which the programmer may then use
to make determinations regarding the performance of a lead group
and characteristics of cross signals between leads. In one example,
the programmer may compute an impedance measurement associated with
a lead group to determine the group's performance. In this example,
the programmer may determine impedance between electrodes using the
measurements by the IMD, or information regarding distances between
electrodes and body tissue conductivity. In another example, the
programmer may determine the inter-region and intra-region
measurements based on lead distances, which the programmer may
estimate using the images and lead dimension which may be known. In
this example, the programmer may disallow a certain combination of
electrodes if the lead distance exceeds a specified threshold
(e.g., 10 cm). The threshold may be a default value or may be
defined by the user. In another example, the programmer may
instruct the IMD to measure signal amplitude at one electrode
resulting from a stimulation pulse on a second electrode, to
determine the effect of the electrodes on one another. In this
manner, the IMD may provide measurements to the programmer, which
uses the measurements to guide the user as to which electrodes may
be programmed together, which electrodes have cross signals, which
electrodes may not be programmed together, and the like.
[0107] The measurements of inter-region and intra-region signals
may be included in the programming of each lead group. For example,
if a lead group is programmed to deliver stimulations at certain
amplitude, any signal effects resulting from other leads or other
regions may be taken into account in presenting the actual
stimulation that will be delivered. For example, if there are
contributions from other lead groups, a delivered stimulation for a
lead group may not be at a specified amplitude, but the overall
result of the stimulation actually delivered by the lead may have
the desired amplitude. Instead of specifying measurements for each
lead, the programmer may allow the user to define an area to which
stimulation is to be delivered and to exclude those areas not
included in the defined area, and the programmer may configure the
leads according to the defined area taking into consideration
intra- and inter-region interferences. Additionally, it should be
understood that using 4 leads per region and only 4 regions as
shown in the figures is only illustrative, and more leads and/or
more regions may be defined using the techniques described in this
disclosure.
[0108] In accordance with this disclosure, some parameters may be
global parameters and may be batch programmed for all regions.
Global parameters may be, for example, a master rate (the maximum
rate at which the programs may run, for example, the master rate
may be 100 Hz, and the rate for each program specified per region
may defined as a fraction of the master rate), soft start value
(the amount of time it takes stimulation to go from 0 to its full
amplitude), PW limit on/off (whether the patient can increase or
decrease the pulse width--if PW limit is ON, patient is able to
increase or decrease the PW, and if it's OFF, then the patient has
no control), rate limit on/off (whether the rate limit may be
increased or decreased), preferred upper amplitude limit (the upper
limit of the amplitude above which a patient may not increase the
amplitude, this limit has to be lower or equal to the amplitude
(defined next), if the amplitude is 15 mA for example, the
preferred upper amplitude limit has to be 15 mA or less), amplitude
(the amplitude of the pulse, for example, 25 mA), stimulation
on/off (whether the stimulation is on or off), and return to
initial settings (this setting may be used if a user adjusts a
patient's program during a clinic visit, then for some reason wants
to revert to the device settings when the patient came in).
[0109] Other parameters may be programmed on region-by-region basis
on a region level. Some region level parameters may be, for
example, master amplitude (the amplitude for the program specific
to the region, and it cannot exceed the preferred upper amplitude
limit), electrode amplitude (each electrode of each lead delivering
therapy to the region may have its own amplitude), pulse width (the
pulse width for the signal of the specific region), slot rate (the
fraction of the master rate that defines the rate for the program,
this may be a fraction such as, 1/4, which means the rate for the
specific program is 1/4 of the master rate, e.g., 100 Hz, therefore
25 Hz), posture 1/2 amplitude (each slot or program can have its
own amplitude, additionally, each posture (standing, sitting, lying
down on back, etc.) may have an associated amplitude, when the
device senses that the patient changed positions or postures, the
associated amplitude is utilized), cycling on/off times (this
parameter indicates how long stimulation is on and how long it is
off for a specific region), cycling on/off state (this determines
whether the cycling feature is on or off, if cycling in on, then
the cycling on/off times are applied to the stimulations, and if
cycling is off, then stimulation is always on), amplitude
upper/lower limits (the upper and lower limits of the amplitude for
the program of the specific region, if a patient is able to
increase or decrease the amplitude, these limits may be imposed),
program name (the name specified by the user for each program,
e.g., Region 1, or Epidural Thoracic, etc.), PRS on/off (whether
posture amplitudes are applied, when PRS is ON, the amplitude is
altered when posture is changed, and when PRS is OFF the amplitude
is the same regardless of posture), and delete program. Other
parameters may be specified on the global or regional level to
accommodate the therapy, the device, and the regions, and are not
limited to the exemplary parameters described herein for
illustrative purposes.
[0110] In an example implementation using the techniques of the
disclosure, a user programmer 40 may be used to define one or more
therapy regions to which stimulation may be applied by implantable
stimulator 34. The stimulation may be applied using
previously-defined lead placements or by defining lead placements.
Multiple regions may be defined by the user, and for each region
one or more leads may be used to deliver stimulation therapy. In
one example, a lead may be used to provide stimulation therapy to
one or more regions.
[0111] The user may graphically define one or more desired
stimulation regions using the user interface 59. The user interface
may allow a user to view a combined image of the region where the
leads may be implanted and graphical layer representing placement
of the leads. The image of the region may be retrieved from the
implantable stimulator 34 where it may have been stored during a
previous session or may be captured by an image capturing device
during the current session.
[0112] An image capturing device may be used to capture an image of
the electrode placement for each of the therapy regions. The image
capturing device may be a camera built into the programmer 40 and
may be controlled by the user interface 59 or may have its own
control panel. Alternatively, the image capturing device may be a
camera connected to the programmer 40 via an interface, such as a
universal serial bus (USB) interface, or a network interface (e.g.,
Ethernet, Wi-Fi, or the like).
[0113] A captured image may be manipulated by functions such as,
for example, zooming, rotating, panning, cropping, and placing
annotations on the image. The image may be compressed and other
functions such as, cropping and converting to gray scale, for
example, may be used to further reduce the size of the image.
Metadata may be also associated with the image to enable a
subsequent user to retrieve information regarding the region, the
applied therapy, and other information related to the patient and
the therapy received. The image may then be used to define therapy
for a current session, or may be stored in the stimulator 34 for
subsequent retrieval for future therapy.
[0114] The user may obtain an image by, for example, making a
selection on the user interface 59 to capture a screen shot of the
image as it appears on the user interface 59. The user may also
capture the image using the image capturing device by obtaining a
digital photograph off of the screen or a print out of the screen
of an imaging machine, e.g., a fluoroscopy machine, which may be
connected to the programmer 40. The captured image may be an image,
produced by a fluoroscopic imaging device, for example, and may be
a still or a moving image.
[0115] The captured image may then be manipulated by the user for
therapy application. The user may define multiple regions and the
lead placement in the captured image. For each region, the user may
define a set of leads to use for application of therapy to the
region. The user may scale, stretch, move, or rotate the lead
images to match the lead placement in the image of the therapy.
Additionally, the user may perform other functions such as, for
example, zooming, panning, and moving within the image, and adding
annotations.
[0116] In one example, the therapy may be defined by specifying an
electrode combination and specifying parameters associated with the
leads and/or electrodes. In another example, the therapy may be
defined using zone-based programming, through which the user may
graphically define desired stimulation fields and may also define
desired therapy intensity. Based on the defined stimulation field
and therapy intensity, the contribution of each electrode used in
the region may be automatically determined.
[0117] Additionally, while aspects of this disclosure are described
in the context of a stimulator as an IMD, techniques described
herein may be utilized in other types of medical devices which may
be implantable. For example, techniques of the disclosure may be
utilized with any type of a neurostimulator, or implantable fluid
pumps where an image may show catheter configuration, and where
therapy is delivered by pumping fluid such as blood, insulin, pain
relief agents, or other medicine to the targeted therapy
region.
[0118] The techniques described in this disclosure may be
implemented, at least in part, in hardware, software, firmware or
any combination thereof. For example, various aspects of the
techniques may be implemented within one or more microprocessors,
digital signal processors (DSPs), application specific integrated
circuits (ASICs), field programmable gate arrays (FPGAs), or any
other equivalent integrated or discrete logic circuitry, as well as
any combinations of such components, embodied in programmers, such
as physician or patient programmers, stimulators, or other devices.
The terms "processor," "processing circuitry," "controller" or
"control module" may generally refer to any of the foregoing logic
circuitry, alone or in combination with other logic circuitry, or
any other equivalent circuitry, and alone or in combination with
other digital or analog circuitry.
[0119] For aspects implemented in software, at least some of the
functionality ascribed to the systems and devices described in this
disclosure may be embodied as instructions on a computer-readable
medium such as random access memory (RAM), read-only memory (ROM),
non-volatile random access memory (NVRAM), electrically erasable
programmable read-only memory (EEPROM), FLASH memory, magnetic
media, optical media, or the like. The instructions may be executed
to support one or more aspects of the functionality described in
this disclosure.
[0120] Various examples of the invention have been described. These
and other examples are within the scope of the following
claims.
* * * * *