U.S. patent application number 13/913798 was filed with the patent office on 2014-02-27 for portable assemblies, systems, and methods for providing functional or therapeutic neurostimulation.
This patent application is currently assigned to NDI MEDICAL, LLC.. The applicant listed for this patent is Maria E. Bennett, Joseph W. Boggs, III, Stuart F. Rubin, Kenneth P. Rundle, Johnathan L. Sakai, Robert B. Strother, Geoffrey B. Thrope. Invention is credited to Maria E. Bennett, Joseph W. Boggs, III, Stuart F. Rubin, Kenneth P. Rundle, Johnathan L. Sakai, Robert B. Strother, Geoffrey B. Thrope.
Application Number | 20140058495 13/913798 |
Document ID | / |
Family ID | 41610659 |
Filed Date | 2014-02-27 |
United States Patent
Application |
20140058495 |
Kind Code |
A1 |
Sakai; Johnathan L. ; et
al. |
February 27, 2014 |
PORTABLE ASSEMBLIES, SYSTEMS, AND METHODS FOR PROVIDING FUNCTIONAL
OR THERAPEUTIC NEUROSTIMULATION
Abstract
Neurostimulation assemblies, systems, and methods make possible
the providing of short-term therapy or diagnostic testing by
providing electrical connections between muscles and/or nerves
inside the body and stimulus generators and/or recording
instruments mounted on the surface of the skin or carried outside
the body. Neurostimulation assemblies, systems, and methods may
include a carrier and an electronics pod, the electronics pod
including stimulation generation circuitry and user interface
components. A power source and/or flash memory may be incorporated
in neurostimulation assembly and/or the return electrode. The
assemblies, systems, and methods are adapted to provide coordinated
neurostimulation to multiple regions of the body.
Inventors: |
Sakai; Johnathan L.;
(Fairview Park, OH) ; Bennett; Maria E.;
(Lyndhurst, OH) ; Boggs, III; Joseph W.;
(Carrboro, NC) ; Strother; Robert B.; (Willoughby
Hills, OH) ; Thrope; Geoffrey B.; (Shaker Heights,
OH) ; Rundle; Kenneth P.; (Independence, OH) ;
Rubin; Stuart F.; (Orange Village, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sakai; Johnathan L.
Bennett; Maria E.
Boggs, III; Joseph W.
Strother; Robert B.
Thrope; Geoffrey B.
Rundle; Kenneth P.
Rubin; Stuart F. |
Fairview Park
Lyndhurst
Carrboro
Willoughby Hills
Shaker Heights
Independence
Orange Village |
OH
OH
NC
OH
OH
OH
OH |
US
US
US
US
US
US
US |
|
|
Assignee: |
NDI MEDICAL, LLC.
Cleveland
OH
|
Family ID: |
41610659 |
Appl. No.: |
13/913798 |
Filed: |
June 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12462384 |
Aug 3, 2009 |
8463383 |
|
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13913798 |
|
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61137652 |
Aug 1, 2008 |
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Current U.S.
Class: |
607/149 |
Current CPC
Class: |
A61N 1/36017 20130101;
A61N 1/36003 20130101; A61N 1/0496 20130101; A61N 1/0551 20130101;
A61N 1/36021 20130101 |
Class at
Publication: |
607/149 |
International
Class: |
A61N 1/04 20060101
A61N001/04 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0005] This invention was made with government support under grant
no. 1R43AR052211-01 awarded by the National Institutes of Health,
through the National Institute of Arthritis and Musculoskeletal and
Skin Diseases. The Government has certain rights in the invention.
Claims
1. A surface mounted electrode comprising: a top layer and a bottom
layer, the bottom layer adapted to provide electrical contact and
adhesion to a patient, a power source positioned between the top
layer and the bottom layer, and electrically coupled to the bottom
layer and a cable assembly, and a connector electrically coupled to
the cable assembly, the cable assembly and connector adapted to
provide electrical contact between the power source and a
neurostimulation assembly.
2. An electrode according to claim 1: wherein at least one
conductor of the cable assembly comprises a carbon-fiber wire.
3. An electrode according to claim 2: wherein the carbon-fiber wire
is adapted to make intimate contact with the bottom layer.
4. An electrode according to claim 1: wherein the top layer
comprises an adhesive-backed fabric.
5. An electrode according to claim 1: wherein the bottom layer
comprises a conductive hydrogel material adapted to be placed on
the skin.
6. An electrode according to claim 1: wherein the power source is
adapted to be sandwiched between layers of non-conductive
material.
7. An electrode according to claim 1: wherein the layers of
non-conductive material and the power source sandwiched there
between is sandwiched between the top layer and the bottom
layer.
8. An electrode according to claim 1: wherein the connector is
touch proof and/or water proof.
9. An electrode according to claim 1: wherein the power source
comprises a flexible power source.
10. An electrode according to claim 1: wherein the power source
comprises a capacity of about 1 mA-hr to about 1000 mA-hr.
11. An electrode according to claim 1: further including
non-volatile memory positioned between the top layer and the bottom
layer.
12. A method comprising: providing a surface mounted electrode as
defined in claim 8, placing the electrode on a tissue surface, and
coupling the electrode to a neurostimulation assembly
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/462,384, entitled "Portable Assemblies, Systems, and
Methods for Providing Functional or Therapeutic Neurostimulation,"
filed Aug. 3, 2009, which is hereby incorporated in its entirety by
reference.
[0002] U.S. patent application Ser. No. 12/462,384, claims benefit
from U.S. Provisional Patent Application No. 61/137,652, entitled
"Portable Assemblies, Systems, and Methods for Providing Functional
or Therapeutic Neurostimulation," filed on Aug. 1, 2008, and claims
the benefit of U.S. Provisional Patent Application Ser. No.
61/137,652, filed Aug. 1, 2008, and entitled "Portable Assemblies,
Systems, and Methods for Providing Functional or Therapeutic
Neurostimulation," both of which are hereby incorporated by
reference. U.S. patent application Ser. No. 12/462,384 is a
continuation-in-part of U.S. patent application Ser. No.
11/978,824, filed Oct. 30, 2007, and entitled "Portable Assemblies,
Systems and Methods for Providing Functional or Therapeutic
Neuromuscular Stimulation," which is a divisional application of
U.S. patent application Ser. No. 11/595,556, filed Nov. 10, 2006,
and entitled "Portable Assemblies, Systems and Methods for
Providing Functional or Therapeutic Neuromuscular Stimulation,"
which claims the benefit of U.S. Provisional Patent Application
Ser. No. 60/801,315, filed May 18, 2006, and entitled "Portable
Assemblies, Systems, and Methods for Providing Functional or
Therapeutic Neuromuscular Stimulation," which are incorporated
herein by reference.
[0003] U.S. patent application Ser. No. 12/462,384 is also a
continuation-in-part of U.S. patent application Ser. No.
11/056,591, filed Feb. 11, 2005, and entitled "Portable Assemblies,
Systems and Methods for Providing Functional or Therapeutic
Neuromuscular Stimulation," which claim the benefit of U.S.
Provisional Patent Application Ser. No. 60/551,945, filed Mar. 10,
2004, and entitled "Steerable Introducer for a Percutaneous
Electrode Usable in Association with Portable Percutaneous
Assemblies, Systems and Methods for Providing Highly Selective
Functional or Therapeutic Neurostimulation," which are all
incorporated herein by reference.
[0004] U.S. patent application Ser. No. 12/462,384 is also a
continuation-in-part of U.S. patent application Ser. No.
11/545,339, filed Oct. 10, 2006, and entitled "Portable
Percutaneous Assemblies, Systems and Methods for Providing Highly
Selective Functional or Therapeutic Neurostimulation," which is a
continuation of U.S. patent application Ser. No. 10/777,771, now
U.S. Pat. No. 7,120,499, filed Feb. 12, 2004, and entitled
"Portable Percutaneous Assemblies, Systems and Methods for
Providing Highly Selective Functional or Therapeutic
Neurostimulation," which are all incorporated herein by
reference.
FIELD OF INVENTION
[0006] This invention relates to assemblies, systems, and methods
for providing neurostimulation to tissue.
BACKGROUND OF THE INVENTION
[0007] Neurostimulation, i.e., neuromuscular stimulation (the
electrical excitation of nerves and/or muscle to directly elicit
the contraction of muscles) and neuromodulation stimulation (the
electrical excitation of nerves, often afferent nerves, to
indirectly affect the stability or performance of a physiological
system) and brain stimulation (the stimulation of cerebral or other
central nervous system tissue) can provide functional and/or
therapeutic outcomes. While existing systems and methods can
provide remarkable benefits to individuals requiring
neurostimulation, many quality of life issues still remain. For
example, existing systems perform a single, dedicated stimulation
function, and are unable to operate in a fashion to provide
coordinated stimulation to multiple regions of a body. Furthermore,
these controllers are, by today's standards, relatively large and
awkward to manipulate and transport.
[0008] There exist both external and implantable devices for
providing neurostimulation in diverse therapeutic and functional
restoration indications. These neurostimulators are able to provide
treatment therapy to individual portions of the body. The operation
of these devices typically includes the use of an electrode placed
either on the external surface of the skin and/or a surgically
implanted electrode. In the case of external neurostimulators,
surface electrodes and/or percutaneous lead(s) having one or more
electrodes are used to deliver electrical stimulation to the select
portion(s) of the patient's body.
[0009] Several clinical and technical issues associated with
surface electrical stimulation have prevented it from becoming a
widely accepted treatment method. First, stimulation of cutaneous
pain receptors cannot be avoided resulting in stimulation-induced
pain that limits patient tolerance and compliance. Second,
electrical stimulation is delivered at a relatively high frequency
to prevent stimulation-induced pain, which leads to early onset of
muscle fatigue. Third, it is difficult to stimulate deep muscles
with surface electrodes without stimulating overlying, more
superficial muscles resulting in unwanted stimulation. Finally,
clinical skill and intensive patient training is required to place
surface electrodes reliably on a daily basis and adjust stimulation
parameters to provide optimal treatment. The required daily
maintenance and adjustment of a surface electrical stimulation
system is a major burden on both patient and caregiver.
[0010] It is time that systems and methods for providing
neurostimulation address not only specific prosthetic, functional,
or therapeutic objections, but also address the quality of life of
the individual requiring neurostimulation, including the ability to
operate a neurostimulation device without concern for replenishing
a power source, and to provide coordinated stimulation to multiple
regions of a body.
SUMMARY OF THE INVENTION
[0011] The invention provides improved assemblies, systems, and
methods for providing prosthetic or therapeutic
neurostimulation.
[0012] One aspect of the invention provides portable, percutaneous
or surface mounted neurostimulation assemblies, systems and methods
that provide electrical connections between muscles or nerves
inside the body and stimulus generators and/or recording
instruments temporarily mounted/positioned on the surface of the
skin or carried outside the body.
[0013] The assemblies, systems, and methods may, in use, be coupled
by percutaneous leads to electrodes, which are implanted below the
skin surface, or, alternatively, may be coupled to surface mounted
electrode(s), or both, and positioned at a targeted tissue region
or regions. The neurostimulation assemblies, systems, and methods
apply highly selective patterns of neurostimulation only to the
targeted region or regions, to achieve one or more highly selective
therapeutic and/or functional and/or diagnostic outcomes. The
patterns can vary according to desired therapeutic and/or
diagnostic objectives. The indications can include, e.g., the
highly selective treatment of pain or muscle dysfunction, and/or
the highly selective promotion of healing of tissue or bone, and/or
the highly selective diagnosis of the effectiveness of a
prospective functional electrical stimulation treatment by a
future, permanently implanted device. In addition, the controller
interface from the user to the neurostimulation assemblies,
systems, and methods may be wireless or may be manually entered via
a user interface on the assembly.
[0014] The neurostimulation assemblies, systems, and methods may
comprise a disposable patch or carrier. The carrier can be readily
carried, e.g., by use of a pressure-sensitive adhesive and/or
covered by a covering bandage, such as Tegaderm.TM., without
discomfort and without affecting body image on, for example, an
arm, a leg, or torso of an individual. In place of worn on the
skin, the patch or carrier may also be carried by the patient, such
as in a pocket, or secured to clothing, a bed, or to movable
devices to allow for patient mobility, or alternatively, the
carrier may include a strap to hold the assembly on an arm, a leg,
or a torso, for example.
[0015] The carrier carries an electronics pod, which generates the
desired electrical current patterns. The pod houses
microprocessor-based, programmable circuitry that generates
stimulus currents, time or sequence stimulation pulses, monitors
system status, and logs and monitors usage, for example. The
electronics pod may be configured, if desired, to accept wireless
RF based commands for both wireless programming and wireless
patient control.
[0016] The electronics pod may also include one or more connection
regions, to physically and electrically couple percutaneous
electrode leads and a surface mounted return electrode to the
circuitry of the electronics pod, provide access for a
programming/communication device, and alternatively provide for
networking of multiple assemblies.
[0017] The electronics pod and/or the return electrode may further
include a power source. The power source provides power to the
electronics pod for the predetermined functional life of the
neurostimulation assemblies, systems and methods, which may be
hours, days, weeks, months, or up to years. The power source may
comprise a removable or non-removable, replaceable or
non-replaceable, and rechargeable or non-rechargeable power
source.
[0018] A communication/programming device may be plugged into a
mating communications interface on the electronics pod, or the
neurostimulation assemblies, systems and methods may include a
wireless interface to an external device. Through this link, a
caregiver or clinician can individually program the operation of a
given electronics pod. If need be, the caregiver or clinician can
modulate various stimulus parameters in real time.
[0019] Another aspect of the invention provides assemblies,
systems, and methods for providing neurostimulation comprising at
least one electrode, a disposable carrier sized and configured to
be worn by a user, an electronics pod carried on-board the carrier,
the electronics pod including circuitry configured to generate a
stimulation pulse to the electrode, and a power source electrically
coupled to the circuitry, the power source providing power to the
circuitry for the predetermined functional life of the assemblies,
systems, and methods.
[0020] The electronics pod may also include a visual output, such
as a display carried on-board the electronics pod and/or visible
through the electronics pod. The visual output can also be provided
by an illumination source that illuminates at least a portion of
the electronics pod.
[0021] Another aspect of the invention proves systems and methods
comprising a neurostimulation assembly. The assembly may include at
least one electrode sized and configured for implantation in a
targeted neural or muscular tissue region, a lead electrically
coupled to the electrode and including a connection element adapted
to electrically couple to a carrier, the carrier sized and
configured to be carried by the patient, an electronics pod
removably carried on-board the carrier, the electronics pod
including circuitry configured to generate a stimulation pulse, a
power source electrically coupled to the circuitry, a return
electrode adapted to be electrically coupled to the carrier,
instructions prescribing the release and replacement of the return
electrode according to a preset schedule, and an electrode
connection element carried on-board the carrier that is
electrically coupled to the electronics pod, the electrode
connection element being sized and configured to electrically
engage at least a portion of the connection element of the lead to
electrically couple the electrode to the electronics pod to
percutaneously apply the stimulation pulse to the tissue
region.
[0022] In one embodiment, the carrier is sized and configured to
hold the power source. In another embodiment, the return electrode
is sized and configured to hold the power source. The power source
may be at least on of a non-removable and non-replaceable and
non-rechargeable power source.
[0023] Another aspect of the invention provides assemblies,
systems, and methods comprising a surface mounted electrode. The
electrode comprises a top layer and a bottom layer, the bottom
layer adapted to provide electrical contact and adhesion to a
patient, a power source positioned between the top layer and the
bottom layer, and electrically coupled to the bottom layer and a
cable assembly, and a connector electrically coupled to the cable
assembly, the cable assembly and connector adapted to provide
electrical contact between the power source and a neurostimulation
assembly.
[0024] In one embodiment, at least one conductor of the cable
assembly comprises a carbon-fiber wire. The carbon-fiber wire may
be adapted to make intimate contact with the bottom layer.
[0025] In one embodiment, the power source is adapted to be
sandwiched between layers of non-conductive material. The layers of
non-conductive material and the power source sandwiched there
between may also be sandwiched between the top layer and the bottom
layer. The power source comprises a flexible power source, and may
comprise a capacity of about 1 mA-hr to about 1000 mA-hr.
[0026] In one embodiment, the surface mounted electrode further
includes non-volatile memory positioned between the top layer and
the bottom layer.
[0027] Another aspect of the invention provides assemblies,
systems, and methods comprising providing a surface mounted
electrode as defined in claim 1, placing the electrode on a tissue
surface, and coupling the electrode to a neurostimulation
assembly.
[0028] Other features and advantages of the inventions are set
forth in the following specification and attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a perspective view of a neurostimulation assembly
that provides electrical connections between muscles and/or nerves
inside the body and stimulus generators temporarily mounted on the
surface of the skin or carried outside the body.
[0030] FIGS. 2A and 2B are views of the neurostimulation assembly
shown in FIG. 1 worn or carried on a temporary basis on an external
skin surface of the body.
[0031] FIG. 3 is an exploded side view of an embodiment of the
neurostimulation assembly shown in FIG. 1, showing its coupling to
percutaneous leads to electrodes, which are implanted below the
skin surface in a targeted tissue region or regions.
[0032] FIG. 4 is a perspective view of an embodiment of a
neurostimulation assembly of the type shown in FIG. 1, showing
configurations of covering bandages to secure the electrodes, lead,
and assembly in place for use.
[0033] FIG. 5 is a perspective view of an embodiment of a
neurostimulation assembly of the type shown in FIG. 1 coupled to an
external programming/communication instrument.
[0034] FIG. 6 is a perspective view of an embodiment of a
neurostimulation assembly of the type shown in FIG. 1 in
association with a programming mode key adapted to allow a
clinician access to a programming mode to adjust stimulus
parameters and gather/view usage data.
[0035] FIG. 7 is a block diagram of an embodiment of a circuit that
the neurostimulation assembly shown in FIG. 1 may utilize.
[0036] FIG. 8 is a graphical view of a possible biphasic stimulus
pulse output of the neurostimulation assembly for use with the
system shown in FIG. 1.
[0037] FIGS. 9 to 11 show the use of an electrode introducer to
percutaneously implant an electrode in a targeted tissue region and
for connection to a lead extension as shown in FIG. 3.
[0038] FIG. 12 is a plan view of an embodiment of a kit packaging
the neurostimulation assembly and associated components for use,
along with instructions for use.
[0039] FIG. 13 is an anatomical view showing an alternative
configuration of a neurostimulation assembly and system, the system
including a harnessed multi-channel stimulation assembly capable of
providing coordinated neurostimulation to multiple regions of the
body.
[0040] FIG. 14 is an anatomical view of the system shown in FIG.
13, showing the harnessed multi-channel neurostimulation assembly
configured to be held on a movable stand next to the patient.
[0041] FIG. 15 is an anatomical view showing an additional
alternative configuration of a neurostimulation assembly and
system, the system including a master neurostimulation stimulation
assembly and one or more slave neurostimulation assemblies, with
the master assembly capable of providing coordinated control of
multiple slave neurostimulation assemblies, the system capable of
providing coordinated neurostimulation to multiple regions of the
body.
[0042] FIG. 16 is an exploded view of one embodiment of a surface
return electrode incorporating a powers source and an optional
memory chip.
[0043] Although the disclosure hereof is detailed and exact to
enable those skilled in the art to practice the invention, the
physical embodiments herein disclosed merely exemplify the
invention which may be embodied in other specific structures. While
the desired embodiment has been described, the details may be
changed without departing from the invention, which is defined by
the claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] The various aspects of the invention will be described in
connection with providing neurostimulation for prosthetic or
therapeutic purposes. That is because the features and advantages
that arise due to the invention are well suited to this purpose.
Still, it should be appreciated that the various aspects of the
invention can be applied to achieve other objectives as well.
I. Neurostimulation Assembly Overview
[0045] FIG. 1 shows an exemplary embodiment of neurostimulation
assembly 10. As FIGS. 2A and 2B show, the neurostimulation assembly
10 may be sized and configured so that, in use, it can be
conveniently worn on a temporary basis. By "worn," it is meant that
the assembly 10 may be removably skin mounted (see FIG. 2A), or may
also be carried by the patient (i.e., user), or secured or strapped
(see FIG. 2B) to the patient's arm, leg, waist, clothing, a bed, or
to movable devices to allow for patient mobility. By "temporary,"
it is meant that the presence of the neurostimulation assembly 10
can be well tolerated without discomfort for a period of time from
several hours to a month or two, or more, after which the
neurostimulation assembly 10 can be removed and discarded. During
the period of use, the neurostimulation assembly 10 may be removed
and reattached for hygiene maintenance. The assembly 10 may be
constructed in a manner to conform to the IPX8 standard for water
ingress. The assembly 10 may be constructed in a manner to conform
to lower water ingress standards as well, for limited water contact
applications.
[0046] As FIG. 3 shows, the neurostimulation assembly 10 is, in
use, releasably coupled to a lead 12, including an extension lead
12, with the lead 12 coupled to electrode(s) 14 at connector 13.
The electrodes 14 may be implanted, e.g., percutaneously, below the
skin surface in a targeted tissue region or regions. The tissue
region or regions are targeted prior to implantation of the
electrodes 14 due to their muscular and/or neural morphologies in
light of desired therapeutic and/or functional and/or diagnostic
objectives.
[0047] In use, the neurostimulation assembly 10 generates and
distributes electrical current patterns through the lead 12 to the
electrodes 14 and back to a return electrode. In this way, the
neurostimulation assembly 10 applies highly selective patterns of
neurostimulation only to the targeted region or regions, to achieve
one or more highly selective therapeutic and/or diagnostic
outcomes. As will be described in greater detail later, the
inputs/stimulation parameters can vary according to desired
therapeutic and/or diagnostic objectives. As non-limiting examples,
the outcomes can comprise the highly selective treatment of pain or
muscle dysfunction, and/or the highly selective promotion of
healing of tissue or bone, and/or the highly selective diagnosis of
the effectiveness of a prospective functional electrical
stimulation treatment.
[0048] The neurostimulation assembly 10 will enable a physician to
deliver a lead 12 and electrode 14, such as a fine wire
percutaneous lead 12 and electrode(s) 14 to target locations via a
hypodermic needle and send the patient home with a skin-mounted or
carried or strapped miniature neurostimulation assembly 10. By
delivering the therapy via percutaneous electrodes 14, the barriers
associated with surface stimulation, including cutaneous pain and
unreliable electrode placement are eliminated. The use of
percutaneous electrodes allows the selective, comfortable, and
consistent activation of the muscle(s) (and/or their innervating
nerves) into which the electrode(s) 14 are implanted. Furthermore,
by securing the neurostimulation assembly 10 to the skin near the
treatment site, or strapped near the treatment site, for example,
and eliminating lengthy external cables, the assembly 10 may
enhance the ease of use of electrical stimulation therapy,
improving clinical acceptance and patient compliance.
II. Desirable Technical Features
[0049] The neurostimulation assembly 10 can incorporate various
technical features to enhance its usability, which will now be
described.
[0050] A. The Carrier
[0051] In its most basic form (see FIGS. 1 and 3), the
neurostimulation assembly 10 comprises a disposable patch or
carrier 16. The carrier 16 desirably is sized and configured as a
compact, lightweight, and flexible assembly made, e.g., of an
inert, formed or machined plastic or metal material.
[0052] In a representative embodiment, the carrier 16 may be
generally oval and measure about 50 mm to about 80 mm in height,
and about 30 mm to about 60 mm in width, and about 10 mm to about
20 mm in depth, and more particularly about 60 mm to about 70 mm in
height, and about 40 mm to about 50 mm in width, and about 12 mm to
about 18 mm in depth, or more or less. The neurostimulation
assembly 10 may weigh about 30 grams to about 50 grams, and more
particularly about 40 grams, or more or less.
[0053] It is to be appreciated that the neurostimulation assembly
10 and associated carrier 16 may comprise a variety of sizes,
shapes, and weights, for different applications and/or to increase
or decrease the mounting surface area. At this size, the carrier 16
can be readily worn or carried without discomfort and in a
cosmetically acceptable way (as FIGS. 2A and 2B show). The flexible
carrier material and shape will allow the neurostimulation assembly
10 to be positioned on curved surfaces of the body, such as an arm,
shoulder, leg, stomach, and/or back, for example.
[0054] B. Securing the Neurostimulation Assembly
[0055] The undersurface of the carrier 16 may include an adhesive
region 17. The function of the optional adhesive region 17 is to
temporarily secure the neurostimulation assembly 10 to an external
skin surface during use. For example, an inert, conventional
pressure sensitive adhesive or tape can be used. Desirably, the
dermal adhesive region contains a bacteriostatic sealant that
prevents skin irritation or superficial infection, which could lead
to premature removal.
[0056] In place of, or in conjunction with the adhesive region 17,
covering bandage(s) 19 may be used to temporarily secure the
neurostimulation assembly 10 in place on the external skin surface.
Covering bandages 19 may also be used to temporarily secure an
extension lead 12, and the electrode(s) 14 and the extension lead
connector 13, to the skin surface. The use of one or more skin-like
covering bandages 19 eliminates concerns over lead maintenance and
keeps the assembly 10, extension lead 12, and electrodes 14 from
snagging during bathing, dressing, or personal grooming, for
example.
[0057] In place of, or in conjunction with, the adhesive region 17,
and/or covering bandage(s) 19, the assembly 10 may be held in place
with the use of a strap 22. The strap may incorporate velco and/or
elastic, for example, to allow flexibility and comfort when
temporarily securing the neurostimulation assembly 10 to the
desired body region.
[0058] C. The Electronics Pod
[0059] The carrier 16 may further carry an electronics pod 20,
which generates the desired electrical current patterns and may
incorporate a connector 29 for communication/programming with an
external programming system or controller 46.
[0060] As FIG. 3 shows, the electronics pod 20 can comprise a
component or an assembly, such as a molded plastic component or
assembly that can be sealably secured to the carrier 16. In an
alternative embodiment, the electronics pod 20 may be removable and
replaceable on the carrier 16. Having an electronics pod 20 that
can be separated from the carrier 16 may be desired when the need
to replace a carrier 16, or the electronics pod 20, during a course
of treatment is necessary. For example, replacement of a carrier 16
without replacement of the electronics pod 20 may be desired if the
anticipated length of use of the neurostimulation assembly 10 is
going to be long enough to expect a degradation of adhesive
properties of the adhesive region 17, (if used), or if the adhesive
region 17 includes a return electrode, and may undergo, with use,
degradation of adhesive properties and/or electrical
conductivity.
[0061] Regardless of whether the electronics pod 20 is removable
from the carrier 16, the pod 20 houses microprocessor-based
(microcontroller) circuitry 24 that generates stimulus waveforms,
time or sequence stimulation pulses, logs and monitors usage,
monitors system status, and can communicate directly to the
clinician or indirectly through the use of an external programmer
or controller. As a representative example, the stimulation
desirably has a biphasic waveform (net DC current less than 10
microAmps), adjustable from about 0 mA to about 20 mA based on
electrode type and the tissue type being stimulated, pulse
durations adjustable from about 5 microseconds or less up to about
500 microseconds or more, and a frequency programmable from about 1
Hz to about 150 Hz. Most muscle stimulation applications will be in
the 10 Hz to about 20 Hz region, and pain management may use the
higher frequencies. The stimulus current (amplitude) may be user
selectable and the pulse duration may be limited to clinician
selectable.
[0062] The circuitry 24 desirably includes non-volatile memory,
such as a flash memory device or an EEPROM memory chip to carry
embedded, programmable code 26. The code 26 expresses the
pre-programmed rules or algorithms under which the stimulation
timing and command signals are generated. The circuitry 24 can be
carried in a single location or at various locations in and/or on
the pod 20, and/or return electrode 70, and may be fabricated on
flexible or flex-rigid PC board using a very high density
technique.
[0063] D. Lead Connectors
[0064] As FIGS. 1 and 3 show, the electronics pod 20 also includes
one or more connectors 27, 28, 30. The function of the lead
connector 27 is to physically and electrically couple the terminus
of the return electrode 18 to the circuitry 24 of the electronics
pod 20. In the illustrated embodiments, the lead connector 27
comprises a pig-tail cable extending off the electronics pod 20 and
ending with a connector 29. It is to be appreciated that the
pig-tail cable could-extend off the carrier 16 as well. It is also
to be appreciated that the connector 29 could be integral with the
electronics pod 20 or carrier 16 as well, i.e., without the
pig-tail cable.
[0065] Connector 28 physically and electrically couples the
terminus of the lead 12, or extension if used, to the circuitry 24
of the electronics pod 20. When multiple channels are used, the
connector 28 is able to distribute the electrical current patterns
in channels, i.e., each electrode 14 comprises a channel, so that
highly selective stimulation patterns can be applied through
multiple electrodes 14. One or more channels may be provided, i.e.,
two electrodes 14.
[0066] Connector 30 may be provided as an option for physically and
electrically coupling a communication/programming device 46 to the
circuitry 24 of the electronics pod 20, i.e., connector 30 can
serve as a communication interface. As FIG. 5 shows, the connector
30 can be used to couple to an external programming device or
computer 46. Through this link 58, information and programming
input can be exchanged and data can be downloaded from the
electronics pod 20. This connector may be normally plugged with a
rubber seal and only accessed during device
communication/programming.
[0067] It should be appreciated, of course, that instead of using a
cable interface 58, as shown, a wireless link 59 (e.g., RF
magnetically coupled, infrared, or RF for example) could be used to
place the electronics pod 20 in communication with an external
programming device 46 or computer.
[0068] The connectors 28, 29, and 30 may be touch proof and/or
water proof connectors to help maintain a consistent and reliable
electrical connection. Each connector may be labeled with a number
or other indicia to identify the channel of the electronics
circuitry 24 that is coupled to each connector.
[0069] It is to be appreciated that alternative embodiments are
possible. Coupling the extension lead 12, return electrode 18, 70,
and device 46 to the electronics pod 20 or carrier 16, can be
accomplished by a locking motion, a button, or a lever arm, or an
Allen drive that is pushed, or slid, or pulled, or twisted, for
example.
[0070] E. The Power Source
[0071] 1. Internal Power Source
[0072] One embodiment of the power source 32 can be described as a
self-contained, limited life power source. The power source 32 may
comprise one or more known power sources, such as capacitor(s) or
battery(ies) 32, e.g., an alkaline, lithium, or Silver Oxide
battery to provide the power to the electronics pod 20 (see FIG.
3). The power source may be selected based on the predetermined
functional life of the assembly 10. As non-limiting examples,
embodiments of the assembly 10 may be preconfigured for a
functional life of one hour, day, week, month, year, two years,
five years, or more or less. The power source 32 capacity may be
sized to match the stimulation output capabilities of the assembly
10 for a predetermined amount of time, such as an hour, day, week,
month, or year(s), for example. As another non-limiting example,
one embodiment of the assembly 10 may be preconfigured for a
functional life of two months. The power source 32 capacity would
be sized to match the stimulation output capabilities of the
assembly 10 for at least the two month period. It is to be
appreciated that the neurostimulation assembly 10 may incorporate a
wide range of power source capacities to reduce or extend the
predetermined functional life of the assembly.
[0073] The circuitry 24 may be used to electronically store
information about the power source 32. The circuitry 24 may include
a non-volatile memory 26 to store the power source and other
information. The estimated remaining capacity of the power source
32 may be stored. The circuitry 24 may also identify the total
power usage (service time) provided to date by the power
source.
[0074] In one embodiment, the power source 32 may be
non-replaceable, non-removable, and/or non-rechargeable. The
neurostimulation assembly 10 may not require or allow the user to
replace the power source 32 for the entire length of the temporary
therapy, e.g., the power source capacity may be sized to function
for the predetermined functional life of the assembly and/or the
treatment period. Other external stimulators require that the user
replace and/or recharge a battery as frequently as once per week.
This task can be difficult for post-stroke patients who have
compromised hand function on the hemiplegic side.
[0075] The power source 32 may be inaccessible to battery
replacement. In one embodiment, the power source 32 may be secured
within the electronics pod 20. The electronics pod 20 may comprise
a molded plastic housing, the housing may include multiple pieces
and may be made inaccessible by sonic welding, gluing, or other
permanent fastening methods, to secure the housing together.
[0076] A power budget for the circuitry 24 was developed based on
the neurostimulation assembly's performance specifications and
expected operating characteristics of the key circuit components
(based on component specifications). Based on the power budget, a
500 mA-hr to 600 mA-hr primary cell battery may provide a service
life sufficient for the neurostimulation assembly's performance
specifications and expected operating characteristics, although it
is to be appreciated that smaller and/or larger capacities may be
used, such as from about 10 mA-hr to about 1000 mA-hr, or more or
less. Combined with the desired size and shape of the
neurostimulation assembly 10, Lithium primary cell types available
from domestic suppliers were considered candidates. In one
embodiment, representative battery configurations include two L92
(AAA) 1.5V Li/FeS.sub.2 cells in series (each cell is 10 mm
diameter.times.44 mm long); or four 1/3N (1/3 `N` cell size) 3.0V
Li/MnO.sub.2 cells in parallel (each cell is 11.5 mm
diameter.times.10.6 mm long).
[0077] 2. External Power Source
[0078] In one embodiment, the return electrode 70, e.g., surface
electrode, may include an embedded power source 72, and optionally
non-volatile memory, such as flash memory 73. The return electrode
70 may be adapted to provide power and a return path, and
optionally stimulus parameters stored in the memory 73, for the
neurostimulation assembly 10. The return electrode 70 may be
adapted to provide an electrical connection to the patient, and
provide power to the neurostimulation assembly 10.
[0079] One embodiment of the return electrode 70 shown in FIG. 16
may comprise a top layer 74 and a bottom layer 75. The top and
bottom layers may be typical of the construction of TENS/NMES
return surface electrodes. The top layer 74 may be an
adhesive-backed fabric, for example, such as a non-woven (i.e.,
non-porous) medical tape. The bottom layer 75 may be a conductive
hydrogel, which provides electrical contact and adhesion to the
patient. The hydrogel may be selected to provide optimal adhesion
and electrical properties for desired applications.
[0080] The power source 72 may comprise a thin flexible power
source, such as is available from Solicore (Lakeland, Fla.). As a
non-limiting example, a 25.times.29.times.0.5 mm flexible power
source with a capacity of 10 mA-hr may be used, although other
dimensions and capacities are within the scope of the invention for
a variety of applications (e.g., 1 mA-hr to 1000 mA-hr). The power
source 72 and/or the optional flash memory 73 may be positioned
between the top and bottom layers 74, 75. The power source 72 and
the optional-flash memory 73 may also be sandwiched between one
layer folded or two separate layers, for example, of non-conductive
material 76, such as an envelope of flexible film. This sandwich of
two non-conductive layers and the power source, and optional flash
memory, may then be positioned between the top and bottom layers
74, 75.
[0081] A cable assembly 77 may be electrically coupled, e.g.,
soldered, to exposed terminals 78 of the power source 72, which may
also be laminated between the non-conductive material 76. Processes
such as pressure-sensitive adhesive, overmolding or hot lamination
may be used to achieve this state. One conductor 79 of the cable
assembly 77 may comprise a carbon-fiber wire, for example, and may
exit the laminated assembly and make intimate contact with the
bottom hydrogel layer 75. The cable assembly 77 may also provide
the electrical connection in common with the power source's
negative contact. A connector 80, such as a touch proof and/or
water proof connector 80, provides electrical contact between the
neurostimulation assembly 10 and the return electrode 70.
[0082] As previously described, optionally, a flash memory chip 73
may be included in the return electrode 70. The memory 73 may, for
example, provide a predetermined set of stimulus parameters for the
neurostimulation assembly 10. This would allow the disposable power
source/return electrode 70 to also provide the prescription of the
stimulus to be delivered.
[0083] The novel combination of a power source and return electrode
allows the neurostimulation assembly 10 to be reduced in size as no
internal power source is required for the assembly 10. The
synergism of integrating the power source 72 with the return
electrode 70 is clear as both may be limited life, disposable
items.
[0084] The optional inclusion of embedded memory 73, such as a
flash memory chip, may permit the clinician to prescribe a
predetermined set of stimulus parameters with just the selection of
the proper return electrode.
[0085] The return electrode with embedded power source takes
advantage of one example of the usage of the neurostimulation
assembly 10, wherein the patient may be changing their return
electrode at predetermined periods, such as every day, or days, or
week, or weeks, or months, to provide a renewed source of power
with each application. This method allows the neurostimulation
assembly 10 to be used indefinitely, as long as a sufficient supply
of return electrodes 70 is prescribed to the patient.
[0086] F. The User Interface
[0087] The assembly 10 as shown in FIGS. 1 and 3 desirably includes
one or more features that provide an interface mechanism for the
patient and/or the clinician. The interface feature allows for the
input and output of neurostimulation assembly information, such as
stimulus regime parameters and system status, and the interface may
be manual, audio, or visual, or a combination. For example, the
electronics pod 20 may include control means 38, e.g., two button
controls, to allow the patient to control stimulation amplitude
setting or some other stimulus intensity adjustment (up-down;
plus-minus; etc.). The electronics pod 20 may also be adapted to
interface with a programming mode key 37, e.g., a magnet, or a
paper clip access switch, for example, to provide control for the
clinician to access clinician controllable settings through the
control means 38, such as the stimulus pulse duration and/or
stimulus frequency and/or stimulus amplitude, for example. As can
be seen, the assembly 10 may include a slot or recess 39 adapted to
accept the programming mode key 37. The programming mode key 37
desirably is in place in order to switch the neurostimulation
assembly 10 into the programming mode and access clinician
controllable settings.
[0088] Table 1 below provides possible stimulus parameter settings.
It is to be appreciated that more or less Stimulus Parameters,
different ranges of Assembly Capabilities, and optional Methods of
Programming are all within the scope of the invention. Table 1 is
only intended as an example of possible settings and capabilities
of the neurostimulation assembly 10.
TABLE-US-00001 TABLE 1 Neurostimulation Stimulus Parameters
Assembly Capabilities Methods of Programming Amplitude, 2-20 mA
Clinician programmable Sustained Pulse Duration, 10-200 .mu.sec
Clinician programmable Sustained Frequency 5-80 Hz Factory
programmable Duty Cycle 10-100% Factory programmable Ramp Times
0-60 seconds Factory programmable Duty Cycle Period 15-900 seconds
Factory programmable Session Duration 1 minute - Factory
programmable continuously # of Sessions 1-1023 sessions Factory
programmable per Day Pause Between 1-1023 minutes Factory
programmable Sessions
[0089] In use, the clinician may be able to program the stimulus
intensity by inserting the programming key 37 (e.g., a small
magnet) into the slot 39 molded into the electronics pod 20. Once
the key 37 is inserted, the clinician may use pushbuttons 38 on the
assembly 10 to evaluate the patient's response to stimulus
intensity settings preconfigured in the assembly. A display 40,
e.g., an LCD or LED display on the top of the assembly shows the
stimulus intensity being delivered. The clinician then selects the
optimal stimulus intensity for the patient from the available
settings.
[0090] When the programming key 37 is not inserted, the
neurostimulation assembly 10 is in the patient mode and stimulus is
automatically provided at the stimulus intensity programmed by the
clinician. The patient can use the two pushbuttons 38 on top of the
assembly to turn the stimulation off or make minor changes to the
stimulus intensity programmed by the clinician.
[0091] The particular setting level can be displayed using the
display 40 to visually identify to the patient the setting level,
and to allow the patient to record the setting within a therapy
diary, which could then be presented to a physician for review. The
operating modes and stimulus parameters may be entered manually
using the control means 38 and/or 37, and easily interpreted via
the visual output or feedback display 40. In one embodiment, the
setting level is a combination of pulse duration and amplitude, the
specifics of which are unknown to the patient. The display 40 may
also provide a data read-out function for the clinician. For
example, the display 40 may provide information such as the total
duration of stimulus provided, the average or median stimulus level
selected by the patient, and perhaps the total duration of no
stimulation provided.
[0092] The display 40 may also provide status information, such as
power source status or system status. For power source status, the
stimulation assembly 10 may indicate the power source 32 has
limited power remaining, or that the power source has provided its
maximum amount of power, as non-limiting examples. For system
status, the stimulation assembly 10 may indicate the electrical
connections to the extension lead 12, electrodes 14, or return
electrode 18 are not working, as non-limiting examples.
[0093] In addition to or in place of the visual feedback display
40, visual output or feedback may also be provided by an
illuminating electronics pod 20, or portions of the electronics
pod. The pod 20 may comprise a material, e.g., a semi-transparent
material, able to allow an illumination source 42, such as one or
more LEDs, to create a "glowing" or "illuminated" appearance. The
illumination source 42 may be coupled to the circuitry 24 within
the electronics pod 20. Status information can be visually provided
to the user by using various blinking or pulsing configurations,
illumination brightness, changing colors, or any combination, for
example. As with the display 40, status information may include
power source status and system status.
III. Representative Neurostimulation Assembly Circuitry
[0094] FIG. 7 shows an embodiment of a block diagram circuit 90 for
the neurostimulation assembly 10 that takes into account the
desirable technical features of the neurostimulation assembly
design discussed above. The circuit 90 can be grouped into
functional blocks, which generally correspond to the association
and interconnection of the electronic components.
[0095] In FIG. 7, five functional blocks are shown: (A) the
Microprocessor Circuitry 24; (B) the Power Source 32; (C) the VHH
Power Supply 94; (D) the Stimulus Output Stage(s) 96; and (E) the
Output Multiplexer 98.
[0096] For each of these blocks, the associated functions, and
possible key components and circuit description are now
described.
[0097] A. The Microcontroller Circuitry
[0098] The microcontroller circuitry 24 may be responsible for the
following functions:
[0099] (1) The timing and sequencing of most of the electronics pod
20 functions including the generation of stimulus pulses and the
quantification of usage by the power source,
[0100] (2) A/D converter to measure output pulse, power source
voltage, and VHH voltage,
[0101] (3) D/A converter may set the pulse amplitude,
[0102] (4) Control for display 40 and/or illumination source
42,
[0103] (5) And alternatively, control for a real time clock; the
real time clock to provide a time signal to the microprocessor
circuitry from the first powering of the electronics pod 20, and
keep time without the presence of the power source 32, 72 for a
predetermined amount of time, such as about one hour, day, week, or
month, or more or less, as non-limiting examples.
[0104] The use of microcontroller based circuitry incorporating
flash programmable memory allows the operating software of the
neurostimulator as well as the stimulus parameters and settings to
be stored in non-volatile memory (data remains safely stored even
when the power source 32, 72, becomes fully discharged or is
removed). The non-volatile memory is also used to store usage
history information, and may also be located in the return
electrode 70.
[0105] Although the microcontroller circuit 24 may be a single
component, the firmware may be developed as a number of separate
modules that deal with specific needs and hardware peripherals. The
functions and routines of these software modules may be executed
sequentially; but the execution of these modules may be timed and
coordinated so as to effectively function simultaneously. The
microcontroller operations that are associated directly with a
given hardware functional block are described with that block.
[0106] The Components of the Microcontroller Circuit may
include:
[0107] (1) A single chip microcontroller 25. This component may be
a member of the Texas Instruments MSP430 family of flash
programmable, micro-power, highly integrated mixed signal
microcontroller. Likely family members to be used include the
MSP430F1610, MSP430F1611, MSP430F1612, MSP430F168, MSP430F169, and
the MSP430FG437. Each of these parts has numerous internal
peripherals, and a micropower internal organization that allows
unused peripherals to be configured by minimal power dissipation,
and an instruction set that supports bursts of operation separated
by intervals of sleep where the microcontroller suspends most
functions.
[0108] (2) A miniature, quartz crystal for establishing precise
timing of the microcontroller. This may be a 32.768 KHz quartz
crystal, for example.
[0109] (3) Miscellaneous power decoupling and analog signal
filtering capacitors.
[0110] B. Internal & External Power Source
[0111] The Power Source 32 and/or 72 (including associated
microcontroller circuitry 24 actions) may be responsible for the
following functions:
[0112] (1) monitor the battery voltage,
[0113] (2) suspend stimulation when the power source voltage
becomes very low,
[0114] (3) discontinue stimulation when the power source has been
used for a predetermined amount of time, e.g., one hour, day, week,
month, two months, year, or whatever time is prescribed by the
clinician, within a margin,
[0115] (4) prevent (with single fault tolerance) the delivery of
excessive current from the power source, and
[0116] (5) provide power to the rest of the circuitry of the
neurostimulation assembly, e.g., VHH power supply.
[0117] In one embodiment, power management controls are generally
included with the electronics pod 20. As previously described, the
circuitry 24 and/or return electrode 70 contains non-volatile
memory, which is adapted to store power source usage information
written by and read by the electronic pod 20.
[0118] (1) The electronics pod 20 and associated microcontroller
circuitry 24 may periodically sample the power source 32, and
periodically update usage data, such as the length of time, or the
total number of pulses for which that the power source has been
used. The circuitry 24 may also be adapted to read and write power
source usage data to the non-volatile memory, 73.
[0119] C. VHH Power Supply
[0120] The VHH power supply 94 is generally responsible for the
following functions:
[0121] (1) Provide the stimulus output stage 96 and multiplexer 98,
if used, with a programmable DC voltage high enough to drive the
required cathodic phase current through the electrode circuit plus
the voltage drops across the stimulator stage, and possibly an
output coupling capacitor. VHH is typically about 12 VDC to about
35 VDC.
[0122] The Components of the VHH Power Supply might include:
[0123] (1) Micropower, inductor based (fly-back topology) switch
mode power supply; e.g., Texas Instruments TPS61045, Texas
Instruments TPS61041, Linear Technology LT1615, or Linear
Technology LT3459, for example.
[0124] (2) The microcontroller circuit 24 monitors VHH for
detection of a VHH power supply failure, system failures, and
optimizing VHH for the exhibited electrode circuit impedance.
[0125] The actual voltage of the internal stimulus power supply
(VHH) may be dynamically adjusted by the stimulator to provide a
minimum, but adequate operating overhead voltage for the stimulus
output stage 96, thus minimizing the battery power consumption.
Although the impedance presented by the lead 12, electrode 14, and
the electrode to tissue interface varies little over time, the
tissue to electrode impedance of the surface mounted return
electrode 18 may vary and represents the majority of the electrode
circuit impedance. A conventional, single inductor, flyback boost
converter circuit topology may be used for the identified supply
and loading conditions. This component may be the Sipex SP6691, or
comparable switch mode power supply.
[0126] D. Stimulus Output Stage
[0127] The Stimulus Output Stage(s) 96 is generally responsible for
the following functions:
[0128] (1) Generate the identified biphasic stimulus current with
selected cathodic phase amplitude, pulse width, and frequency. The
recovery phase may incorporate a maximum current limit; and there
may be a delay time (most likely a fixed delay) between the
cathodic phase and the recovery phase (see FIG. 8). Typical
currents (cathodic phase) vary from about 0.5 mA to about 20 mA
based on the electrode construction and the nature of the tissue
being stimulated. Electrode circuit impedances can vary with the
electrode and the application, but are likely to be less than 2,000
ohms and greater than 100 ohms across a range of electrode
types.
[0129] Two alternative configurations of the stimulus output stage
will be described. In the first configuration:
[0130] (1) The cathodic phase current through the electrode circuit
may be established by a high gain (HFE) NPN transistor with emitter
degeneration shunted by switched shunting resistors to form a
controlled current sink.
[0131] (2) The microcontroller circuit 24 monitors the cathode
voltage to confirm the correct operation of the output coupling
capacitor, to detect system failures, and to optimize VHH for the
exhibited electrode circuit impedance; i.e., to measure the
electrode circuit impedance.
[0132] In a second alternative configuration:
[0133] (1) A low-threshold N-channel MOSFET driven by an op-amp
with fast enable/disable functions to provide a low quiescent
current sink.
[0134] (2) A precision voltage reference of about 2.048V for both
the microcontroller circuit external reference and the current sink
reference.
[0135] (3) Switched shunting resistors may form the controlled
current sink.
[0136] (4) The microcontroller circuit 24 monitors the cathode
voltage to confirm the correct operation of the output coupling
capacitor, to detect system failures, and to optimize VHH for the
exhibited electrode circuit impedance; i.e., to measure the
electrode circuit impedance.
[0137] In either configuration, the switched resistors could be
replaced by a DAC, if available as an on-chip peripheral at the
microcontroller. In either configuration, the start and ending of
the cathodic phase current is timed by the microcontroller.
[0138] E. The Output Multiplexer
[0139] The output multiplexer 98 is required only if more than one
electrode circuit is required. The output multiplexer is
responsible for routing the anode and cathode connections of the
Stimulus Output Stage 96 to the appropriate electrode, i.e.,
electrode(s) 14, and possibly return electrode 18, or both.
[0140] A representative output multiplexer configuration
includes:
[0141] (1) A low ON resistance, micropower, dual 4.times.1 analog
multiplexer; e.g. Maxim MAX4052, MAX384, Vishay DG412HS, or Pericom
PS4066 or PS323 (with separate decoding logic or additional
microcontroller address lines), for example, and
[0142] (2) Microcontroller circuitry 24 selects the electrode
connections to carry the stimulus current (and time the interphase
delay) via address lines.
IV. The Electrodes and their Implantation
[0143] The configuration of the electrodes 14 and the manner in
which they are implanted can vary. A representative embodiment will
be described, with reference to FIGS. 9 to 11.
[0144] In the illustrated embodiment, each lead 12 may comprise a
thin, flexible component made of a metal and/or polymer material.
By "thin," it is contemplated that the lead 12 may not be greater
than about 0.75 mm (0.030 inch) in diameter, although the diameter
may be larger or smaller.
[0145] The lead 12 can comprise, e.g., one or more coiled metal
wires with in an open or flexible elastomer core. The wire can be
insulated, e.g., with a biocompatible polymer film, such as
polyfluorocarbon, polyimide, or parylene. The lead 12 are desirably
coated with a textured, bacteriostatic material, which helps to
stabilize the electrode in a way that still permits easy removal at
a later date and increases tolerance.
[0146] The electrode 14 are electrically insulated everywhere
except at one (monopolar), or two (bipolar), or three (tripolar),
for example, conduction locations near its distal tip. Each of the
conduction locations may be connected to one or more conductors
that run the length of the lead 12, proving electrical continuity
from the conduction location through the lead 12 to the electronics
pod 20. The conduction location may comprise a de-insulated area of
an otherwise insulated conductor that runs the length of an
entirely insulated electrode. The de-insulated conduction region of
the conductor can be formed differently, e.g., it can be wound with
a different pitch, or wound with a larger or smaller diameter, or
molded to a different dimension. The conduction location of the
electrode may comprise a separate material (e.g., metal or a
conductive polymer) exposed to the body tissue to which the
conductor of the wire is bonded.
[0147] In an alternative configuration, the lead 12 does not
utilize an extension 12, rather the lead 12 is electrically
connected to the electronics pod 20 or carrier 16 through an
automated connection method that connects and terminates the
electrode 14.
[0148] The electrode(s) 14 and lead 12 are desirably provided in
sterile packages and desirably possess mechanical properties in
terms of flexibility and fatigue life that provide an operating
life free of mechanical and/or electrical failure, taking into
account the dynamics of the surrounding tissue (i.e., stretching,
bending, pushing, pulling, crushing, etc.). The material of the
electrode desirably discourages the in-growth of connective tissue
along its length, so as not to inhibit its withdrawal at the end of
its use. However, it may be desirable to encourage the in-growth of
connective tissue at the distal tip of the electrode, to enhance
its anchoring in tissue.
[0149] Furthermore, the desired electrode 14 may also include, at
its distal tip, an anchoring element 48 (see FIGS. 10 and 11). In
the illustrated embodiment, the anchoring element 48 takes the form
of a simple barb or bend. The anchoring element 48 is sized and
configured so that, when in contact with tissue, it takes purchase
in tissue, to resist dislodgement or migration of the electrode out
of the correct location in the surrounding tissue. Desirably, the
anchoring element 48 is prevented from fully engaging body tissue
until after the electrode 14 has been deployed. The electrode is
not deployed until after it has been correctly located during the
implantation (installation) process, as will be described in
greater detail later.
[0150] In one embodiment, the lead 12 can include a metal stylet
within its core. Movement of the stylet with respect to the body of
the electrode and/or an associated introducer (if used) is used to
deploy the electrode by exposing the anchoring element 48 to body
tissue. In this arrangement, the stylet is removed once the
electrode 14 is located in the desired region.
[0151] In the illustrated embodiment (see FIGS. 10 and 11), an
electrode 14 may be percutaneously implanted housed within
electrode introducer 50 (i.e., a hypodermic needle). The electrode
introducer 50 comprises a shaft having sharpened needle-like distal
tip, which penetrates skin and tissue leading to the targeted
tissue region. The lead 12 may be loaded (it may be preloaded and
provided in a kit) within a lumen in the introducer 50, with the
anchoring element 48 shielded from full tissue contact within the
shaft of the introducer 50 (see FIG. 9). In this way, the
introducer can be freely manipulated in tissue in search of a
desired final electrode implantation site (see FIG. 10) before
deploying the electrode and withdrawing the introducer 50 (see FIG.
11).
[0152] The electrode introducer 50 may be insulated along the
length of the shaft, except for those areas that correspond with
the exposed conduction surfaces of the electrode 14 housed inside
the introducer 50. These surfaces on the outside of the introducer
50 are electrically isolated from each other and from the shaft of
the introducer 50. These surfaces may be electrically connected to
a connector 64 at the end of the introducer body (see FIGS. 9 and
10). This allows connection to a stimulating circuit 66 (see FIG.
9) during the implantation process. The stimulating circuit 66 may
comprise a stand along stimulator, or the neurostimulation assembly
10 may be the stimulating circuit. Applying stimulating current
through the outside surfaces of the introducer 50 provides a close
approximation to the response that the electrode 14 will provide
when it is deployed at the current location of the introducer
50.
[0153] The electrode introducer 50 is sized and configured to be
bent by hand prior to its insertion through the skin. This will
allow the physician to place an electrode 14 in a location that is
not in an unobstructed straight line with the insertion site. The
construction and materials of the electrode introducer 50 allow
bending without interfering with the deployment of the lead 12 and
withdrawal of the electrode introducer 50, leaving the electrode 14
in the tissue.
V. Installation of the Neurostimulation Assembly
[0154] Prior to installation, a clinician identifies a particular
muscle(s) and/or neural region(s) to which a prescribed therapy
using the neurostimulation assembly 10 will be applied. Once the
particular muscle(s) and/or nerve(s) and/or tissue region or
regions are identified, the clinician proceeds to percutaneously
implant one or more electrodes 14 and leads 12, one by one, through
the desired skin region 68. While each electrode 14 is implanted,
the electrode introducer 50 applies a stimulation signal until a
desired response is achieved indicating the desired placement, at
which time the electrode 14 is deployed and the introducer 50 is
withdrawn.
[0155] Upon implanting each electrode (see FIG. 4, for example),
the clinician is able to route the extension lead 12, if used, to a
lead connector 28 on the electronics pod 20 (or carrier 16).
[0156] The following illustration will describe the use of a
neurostimulator assembly 10 that will be carried or worn on the
patient's exterior skin surface. It is to be appreciated that the
neurostimulator assembly 10 could be carried by the patient or
temporarily secured to a bed or other structure and the lead
extensions 12 extend to the assembly 10. The assembly 10 is placed
around an arm or leg (e.g., with the use of a strap), or on the
skin in a desirable region, that allows electrical connectivity to
the electrode(s) 14, lead 12, and associated connector 28 (see
FIGS. 2A through 3). The carrier 16 may be secured in place with
pressure sensitive adhesive 18 on the bottom of the carrier 16, or
held in place with a covering tape, or with a strap, as previously
described. As previously stated, the adhesive region desirably
contains a bacteriostatic sealant that prevents skin irritation or
superficial infection, which could lead to premature removal.
[0157] After implanting one or more electrodes 14 and placing a
return electrode 18, 70, on the skin surface, the clinician would
be able to route the lead 12 to the electronics pod 20, and couple
the return electrode to the connector 29 to complete the
stimulation path. The neurostimulation assembly 10 is ready for
use.
VI. System Kits
[0158] As FIG. 12 shows, the various devices and components just
described can be consolidated for use in one or more functional
kit(s) 82. The kit can take various forms. In the illustrated
embodiment, the kit 82 comprises a sterile, wrapped assembly. The
kit 82 includes an interior tray 86 made, e.g., from die cut
cardboard, plastic sheet, or thermo-formed plastic material, which
hold the contents. Kit 82 also desirably includes instructions for
use 56 for using the contents of the kit to carry out a desired
therapeutic and/or diagnostic and/or functional objectives.
[0159] The instructions 56 can, of course vary. The instructions 56
shall be physically present in the kits, but can also be supplied
separately. The instructions 56 can be embodied in separate
instruction manuals, or in video or audio tapes, CD's, and DVD's.
The instructions 56 for use can also be available through an
internet web page.
[0160] The arrangement and contents of the kit 82 can vary. For
example, FIG. 12 shows a kit 82 containing the neurostimulation
assembly 10. The instructions for use 56 in the kit 82 may direct a
clinician to place the neurostimulation assembly 10, implant the
electrode 14, couple the electrode 14 to the lead 12, couple the
lead 12 to the assembly 10, and place the return electrode 18 and
couple the return electrode to the assembly 10. The instructions
may also include instructions for the user in the operation of the
neurostimulation assembly 10. Kit 82 may also include an extension
lead 12, and one or more electrodes 14.
[0161] As FIG. 5 shows, external desktop or handheld (desirably
also battery powered) preprogrammed and/or programmable instruments
46 can be used to program stimulus regimes and parameters into the
neurostimulation assembly 10, or to download recorded data from the
neurostimulation assembly 10 for display and further processing.
Instructions for use 56 may describe options for the instruments 46
to communicate with the neurostimulation assembly 10, e.g., by a
cable connection 58, wireless coupling 59, e.g., by radio frequency
magnetic field coupling, by infrared, or by RF wireless, for
example. The communications cable 58 may be adapted to provide
power to the neurostimulation assembly 10 during programming, as
well as communications with the circuitry 24 of the
neurostimulation assembly 10. The external programming instrument
46 can also be a general purpose personal computer or personal
digital device fitted with a suitable custom program and a suitable
cable or interface box for connection to the communications cable
58.
[0162] The programming instruments 46 allow a clinician one option
for customizing the stimulus parameters and regime timing residing
in an individual neurostimulation assembly 10 according the
specific needs of the user and the treatment goals of the
clinician. The neurostimulation assembly 10 can, once customized,
be disconnected from the programming system, allowing portable, or
skin worn operation, as already described. The programming
instruments also allow the retrieval of usage information allowing
the clinician to accurately assess patient compliance with the
prescribed treatment course or regime. Alternatively, and as
previously described, the clinician may use the push buttons 38,
display 40, and/or access through the use of the programming mode
key 37 to program the stimulus parameters and timing and to
retrieve key usage data.
[0163] The foregoing is considered as illustrative only of the
principles of the invention. Furthermore, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and operation shown and described. While the preferred
embodiment has been described, the details may be changed without
departing from the invention, which is defined by the claims.
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