U.S. patent application number 13/368733 was filed with the patent office on 2012-08-09 for leads with segmented electrodes for electrical stimulation of planar regions and methods of making and using.
This patent application is currently assigned to Boston Scientific Neuromodulation Corporation. Invention is credited to Michael Adam Moffitt, Anne Margaret Pianca.
Application Number | 20120203316 13/368733 |
Document ID | / |
Family ID | 46601186 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120203316 |
Kind Code |
A1 |
Moffitt; Michael Adam ; et
al. |
August 9, 2012 |
LEADS WITH SEGMENTED ELECTRODES FOR ELECTRICAL STIMULATION OF
PLANAR REGIONS AND METHODS OF MAKING AND USING
Abstract
One embodiment is a stimulation lead that includes a lead body
having a longitudinal surface, a distal end, and a proximal end;
and multiple electrodes disposed along the longitudinal surface of
the lead body near the distal end of the lead body. The electrodes
include multiple groups of segmented electrodes with each group of
segmented electrodes having multiple segmented electrodes disposed
at a same longitudinal position along the lead. For at least one
first group of segmented electrodes, a first pair of the segmented
electrodes in the first group are disposed on opposite sides of the
lead body and are electrically ganged together by a conductor
therebetween.
Inventors: |
Moffitt; Michael Adam;
(Valencia, CA) ; Pianca; Anne Margaret; (Santa
Monica, CA) |
Assignee: |
Boston Scientific Neuromodulation
Corporation
Valencia
CA
|
Family ID: |
46601186 |
Appl. No.: |
13/368733 |
Filed: |
February 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61440546 |
Feb 8, 2011 |
|
|
|
Current U.S.
Class: |
607/116 ;
607/148 |
Current CPC
Class: |
A61N 1/0534
20130101 |
Class at
Publication: |
607/116 ;
607/148 |
International
Class: |
A61N 1/05 20060101
A61N001/05; A61N 1/04 20060101 A61N001/04 |
Claims
1. A stimulation lead, comprising: a lead body comprising a
longitudinal surface, a distal end, and a proximal end; and a
plurality of electrodes disposed along the longitudinal surface of
the lead body near the distal end of the lead body, the plurality
of electrodes comprising a plurality of groups of segmented
electrodes, each group of segmented electrodes comprising a
plurality of segmented electrodes disposed at a same longitudinal
position along the lead, wherein, for at least one first group of
the plurality of groups of segmented electrodes, a first pair of
the segmented electrodes in the first group are disposed on
opposite sides of the lead body and are electrically ganged
together by a conductor therebetween.
2. The stimulation lead of claim 1, wherein the first group
consists of the first pair of segmented electrodes.
3. The stimulation lead of claim 1, wherein the first group
comprises at least one additional segmented electrode in addition
to the first pair of segmented electrodes, wherein the at least one
additional segmented electrode is not electrically ganged to the
first pair of segmented electrodes.
4. The stimulation lead of claim 3, wherein the at least one
additional segmented electrode comprises a second pair of the
segmented electrodes that are disposed on opposite sides of the
lead body and are electrically ganged together by a conductor
therebetween.
5. The stimulation lead of claim 4, wherein the first pair and the
second pair are radially offset by an angle in a range of 75 to 115
degrees with respect to each other.
6. The stimulation lead of claim 1, wherein the plurality of groups
of segmented electrodes comprises a second group disposed at a
different longitudinal position than the first group, the second
group comprising a second pair of the segmented electrodes which
are disposed on opposite sides of the lead body and are
electrically ganged together by a conductor therebetween.
7. The stimulation lead of claim 6, wherein the first pair and the
second pair are radially offset by an angle in a range of 75 to 115
degrees with respect to each other.
8. The stimulation lead of claim 7, wherein the first pair
longitudinally overlaps with the second pair.
9. The stimulation lead of claim 6, wherein the first and second
pairs of the segmented electrodes are radially aligned with each
other.
10. The stimulation lead of claim 9, wherein the first group
comprises a third pair of the segmented electrodes which are
disposed on opposite sides of the lead body and are electrically
ganged together by a conductor therebetween and the second group
comprises a fourth pair of the segmented electrodes which are
disposed on opposite sides of the lead body and are electrically
ganged together by a conductor therebetween.
11. The stimulation lead of claim 10, wherein the third and fourth
pairs of the segmented electrodes are radially aligned with each
other.
12. The stimulation lead of claim 1, wherein the plurality of
electrodes further comprises at least one ring electrode.
13. The stimulation lead of claim 1, further comprising a plurality
of terminals disposed along the longitudinal surface of the lead
body near the proximal end of the lead body and electrically
coupled to the plurality of electrodes.
14. A kit for implanting a stimulation lead into a patient, the kit
comprising: a stimulation lead comprising a longitudinal surface, a
distal end, and at least one electrode disposed along the
longitudinal surface of the stimulation lead near the distal end of
the stimulation lead, wherein a portion of the stimulation lead
upon which the electrodes are disposed has a non-circular
cross-sectional shape; at least one microelectrode lead comprising
a distal end and at least one microelectrode disposed at the distal
end of the microelectrode lead; and an introducer defining a lumen
configured and arranged to receive the stimulation lead, the
introducer further comprising at least one interior wall extending
into the lumen and defining at least one microelectrode lumen that
is configured and arranged to receive, and hold within the
microelectrode lumen, a one of the at least one microelectrode
leads.
15. The kit of claim 14, wherein the introducer comprises at least
two interior walls defining at least two microelectrode lumens.
16. The kit of claim 14, wherein the stimulation lead further
comprises a proximal end, two main portions disposed at the distal
end of the lead, a bendable portion disposed between the two main
portions, and a plurality of terminals disposed along the proximal
end of the lead and electrically coupled to the plurality of
electrodes, wherein the bendable portion is bent so that the two
main portions are disposed opposite each other and the plurality of
electrodes are disposed on surfaces of the two main portions of the
lead, wherein each electrode has an exposed surface through which
electrical energy can be supplied to stimulate adjacent tissue when
the stimulation lead is implanted.
17. A method for stimulating tissue, the method comprising:
implanting a lead comprising a longitudinal surface, a distal end,
a proximal end, two main portions disposed at the distal end of the
lead, a bendable portion disposed between the two main portions, a
plurality of electrodes disposed on surfaces of the two main
portions of the lead, and a plurality of terminals disposed along
the proximal end of the lead and electrically coupled to the
plurality of electrodes, wherein the bendable portion is bent so
that the two main portions are disposed opposite each other and
wherein each electrode has an exposed surface through which
electrical energy can be supplied to stimulate adjacent tissue when
the stimulation lead is implanted; retaining the lead in the
patient with the bendable portion bent; and stimulating adjacent
tissue using at least one of the electrodes.
18. The method of claim 17, wherein implanting a lead comprising
inserting at least the distal end of the lead into an introducer
defining a lumen configured and arranged to receive the lead, the
introducer further comprising at least one interior wall extending
into the lumen and defining at least one microelectrode lumen that
is configured and arranged to receive a microelectrode lead.
19. The method of claim 17, wherein implanting a lead further
comprises inserting a microelectrode lead into the microelectrode
lumen of the lead body.
20. The method of claim 17, wherein implanting a lead further
comprises using the microelectrode lead to identify tissue for
stimulation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application Ser. No.
61/440,546 filed on Feb. 8, 2011, which is incorporated herein by
reference.
FIELD
[0002] The invention is directed to the area of electrical
stimulation systems and methods of making and using the systems.
The present invention is also directed to electrical stimulation
leads with segmented electrodes that can be used for electrical
stimulation of planar regions, as well as methods of making and
using the segmented electrodes, leads, and electrical stimulation
systems.
BACKGROUND
[0003] Electrical stimulation can be useful for treating a variety
of conditions. Deep brain stimulation can be useful for treating,
for example, Parkinson's disease, dystonia, essential tremor,
chronic pain, Huntington's Disease, levodopa-induced dyskinesias
and rigidity, bradykinesia, epilepsy and seizures, eating
disorders, and mood disorders. Typically, a lead with a stimulating
electrode at or near a tip of the lead provides the stimulation to
target neurons in the brain. Magnetic resonance imaging ("MRI") or
computerized tomography ("CT") scans can provide a starting point
for determining where the stimulating electrode should be
positioned to provide the desired stimulus to the target
neurons.
[0004] After the lead is implanted into a patient's brain,
electrical stimulus current can be delivered through selected
electrodes on the lead to stimulate target neurons in the brain.
Typically, the electrodes are formed into rings disposed on a
distal portion of the lead. The stimulus current projects from the
ring electrodes equally in every direction. Because of the ring
shape of these electrodes, the stimulus current cannot be directed
to one or more specific positions around the ring electrode (e.g.,
on one or more sides, or points, around the lead). Consequently,
undirected stimulation may result in unwanted stimulation of
neighboring neural tissue, potentially resulting in undesired side
effects.
BRIEF SUMMARY
[0005] One embodiment is a stimulation lead that includes a lead
body having a longitudinal surface, a distal end, and a proximal
end; and multiple electrodes disposed along the longitudinal
surface of the lead body near the distal end of the lead body. The
electrodes include multiple groups of segmented electrodes with
each group of segmented electrodes having multiple segmented
electrodes disposed at a same longitudinal position along the lead.
For at least one first group of segmented electrodes, a first pair
of the segmented electrodes in the first group are disposed on
opposite sides of the lead body and are electrically ganged
together by a conductor therebetween.
[0006] Another embodiment is a kit for implanting a stimulation
lead into a patient. The kit includes a stimulation lead having a
longitudinal surface, a distal end, and at least one electrode
disposed along the longitudinal surface of the stimulation lead
near the distal end of the stimulation lead. A portion of the
stimulation lead upon which the electrode(s) are disposed has a
non-circular cross-sectional shape. The kit also includes at least
one microelectrode lead having a distal end and at least one
microelectrode disposed at the distal end of the microelectrode
lead. The kit further includes an introducer defining a lumen
configured and arranged to receive the stimulation lead. The
introducer has at least one interior wall extending into the lumen
and defining at least one microelectrode lumen that is configured
and arranged to receive, and hold within the microelectrode lumen,
one of the at least one microelectrode leads.
[0007] A further embodiment is a method for stimulating tissue that
includes implanting a lead comprising a longitudinal surface, a
distal end, a proximal end, two main portions disposed at the
distal end of the lead, a bendable portion disposed between the two
main portions, multiple electrodes disposed on surfaces of the two
main portions of the lead, and multiple terminals disposed along
the proximal end of the lead and electrically coupled to the
electrodes. The bendable portion is bent so that the two main
portions are disposed opposite each other and each electrode has an
exposed surface through which electrical energy can be supplied to
stimulate adjacent tissue when the stimulation lead is implanted.
The method further includes retaining the lead in the patient with
the bendable portion bent; and stimulating adjacent tissue using at
least one of the electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Non-limiting and non-exhaustive embodiments of the present
invention are described with reference to the following drawings.
In the drawings, like reference numerals refer to like parts
throughout the various figures unless otherwise specified.
[0009] For a better understanding of the present invention,
reference will be made to the following Detailed Description, which
is to be read in association with the accompanying drawings,
wherein:
[0010] FIG. 1 is a schematic side view of one embodiment of a
device for brain stimulation, according to the invention;
[0011] FIG. 2 is a schematic diagram of radial current steering
along various electrode levels along the length of a lead,
according to the invention;
[0012] FIG. 3A is a perspective view of an embodiment of a portion
of a lead having a plurality of segmented electrodes with selected
electrodes electrically ganged, according to the invention;
[0013] FIG. 3B is a perspective view of a second embodiment of a
portion of a lead having a plurality of segmented electrodes with
selected electrodes electrically ganged, according to the
invention;
[0014] FIG. 3C is a perspective view of a third embodiment of a
portion of a lead having a plurality of segmented electrodes with
selected electrodes electrically ganged, according to the
invention;
[0015] FIG. 3D is a perspective view of a fourth embodiment of a
portion of a lead having a plurality of segmented electrodes with
selected electrodes electrically ganged, according to the
invention;
[0016] FIG. 4A is a schematic cross-sectional view of one
embodiment of a lead with a non-circular cross-sectional shape that
can be implanted using a percutaneous introducer, according to the
invention;
[0017] FIG. 4B is a schematic top plan view of a portion of one
embodiment of the lead of FIG. 4A with an example of an electrode
arrangement, according to the invention;
[0018] FIG. 5 is a schematic cross-sectional view of one embodiment
of a lead disposed in an introducer that also contains
microelectrode lumens for receiving microelectrode leads, according
to the invention;
[0019] FIG. 6A is a schematic cross-sectional view of one
embodiment of a lead having two main portions, each containing
electrodes, separated by a bendable portion, according to the
invention; and
[0020] FIG. 6B is a schematic cross-sectional view of one
embodiment of the lead of FIG. 6A with the bendable portion bent
and the lead disposed in a percutaneous introducer, according to
the invention.
DETAILED DESCRIPTION
[0021] The invention is directed to the area of electrical
stimulation systems and methods of making and using the systems.
The present invention is also directed to electrical stimulation
leads with segmented electrodes that can be used for electrical
stimulation of planar regions, as well as methods of making and
using the segmented electrodes, leads, and electrical stimulation
systems.
[0022] A lead for deep brain stimulation may include stimulation
electrodes, recording electrodes, or a combination of both. At
least some of the stimulation electrodes, recording electrodes, or
both are provided in the form of segmented electrodes that extend
only partially around the circumference of the lead. These
segmented electrodes can be provided in sets of electrodes, with
each set having electrodes radially distributed about the lead at a
particular longitudinal position.
[0023] A practitioner may determine the position of the target
neurons using the recording electrode(s) and then position the
stimulation electrode(s) accordingly without removal of a recording
lead and insertion of a stimulation lead. In some embodiments, the
same electrodes can be used for both recording and stimulation. In
some embodiments, separate leads can be used; one with recording
electrodes which identify target neurons, and a second lead with
stimulation electrodes that replaces the first after target neuron
identification. A lead may include recording electrodes spaced
around the circumference of the lead to more precisely determine
the position of the target neurons. In at least some embodiments,
the lead is rotatable so that the stimulation electrodes can be
aligned with the target neurons after the neurons have been located
using the recording electrodes. For illustrative purposes, the
leads are described herein relative to use for deep brain
stimulation, but it will be understood that any of the leads can be
used for applications other than deep brain stimulation, including
spinal cord stimulation and stimulation of other nerves and
tissues.
[0024] Deep brain stimulation devices and leads are described in,
for example, U.S. Pat. No. 7,809,446 ("Devices and Methods For
Brain Stimulation"), U.S. Patent Application Publication No.
2010/0076535 A1 ("Leads With Non-Circular-Shaped Distal Ends For
Brain Stimulation Systems and Methods of Making and Using"), U.S.
Patent Application Publication 2007/0150036 A1 ("Stimulator Leads
and Methods For Lead Fabrication"), U.S. patent application Ser.
No. 12/177,823 ("Lead With Transition and Methods of Manufacture
and Use"), U.S. Patent Application Publication No. 2009/0276021 A1
("Electrodes For Stimulation Leads and Methods of Manufacture and
Use"), U.S. Patent Application Ser. No. 61/170,037 ("Deep Brain
Stimulation Current Steering with Split Electrodes"), U.S. Patent
Application Ser. No. 61/022,953, U.S. Patent Application Ser. No.
61/316,759, U.S. Patent Application Publication No. 2009/0187222
A1, and U.S. Patent Application Ser. No. 61/426,784. Each of these
references is incorporated herein by reference.
[0025] FIG. 1 illustrates one embodiment of a device 100 for brain
stimulation. The device includes a lead 110, a plurality of
electrodes 125 disposed at least partially about a circumference of
the lead 110, a plurality of terminals 135, a connector 130 for
connection of the electrodes to a control unit, and a stylet 140
for assisting in insertion and positioning of the lead in the
patient's brain. The stylet 140 can be made of a rigid material.
Examples of suitable materials for the stylet include, but are not
limited to, tungsten, stainless steel, and plastic. The stylet 140
may have a handle 150 to assist insertion into the lead 110, as
well as rotation of the stylet 140 and lead 110. The connector 130
fits over a proximal end of the lead 110, preferably after removal
of the stylet 140.
[0026] The control unit (not shown) is typically an implantable
pulse generator that can be implanted into a patient's body, for
example, below the patient's clavicle area. The pulse generator can
have eight stimulation channels which may be independently
programmable to control the magnitude of the current stimulus from
each channel. In some cases the pulse generator may have more or
fewer than eight stimulation channels (e.g., 4-, 6-, 16-, 32-, or
more stimulation channels). The control unit may have one, two,
three, four, or more connector ports, for receiving the plurality
of terminals 135 at the proximal end of the lead 110.
[0027] In one example of operation, access to the desired position
in the brain can be accomplished by drilling a hole in the
patient's skull or cranium with a cranial drill (commonly referred
to as a burr), and coagulating and incising the dura mater, or
brain covering. The lead 110 can be inserted into the cranium and
brain tissue with the assistance of the stylet 140. The lead 110
can be guided to the target location within the brain using, for
example, a stereotactic frame and a microdrive motor system. In
some embodiments, the microdrive motor system can be fully or
partially automatic. The microdrive motor system may be configured
to perform one or more the following actions (alone or in
combination): insert the lead 110, retract the lead 110, or rotate
the lead 110.
[0028] In some embodiments, measurement devices coupled to the
muscles or other tissues stimulated by the target neurons, or a
unit responsive to the patient or clinician, can be coupled to the
control unit or microdrive motor system. The measurement device,
user, or clinician can indicate a response by the target muscles or
other tissues to the stimulation or recording electrode(s) to
further identify the target neurons and facilitate positioning of
the stimulation electrode(s). For example, if the target neurons
are directed to a muscle experiencing tremors, a measurement device
can be used to observe the muscle and indicate changes in tremor
frequency or amplitude in response to stimulation of neurons.
Alternatively, the patient or clinician may observe the muscle and
provide feedback.
[0029] The lead 110 for deep brain stimulation can include
stimulation electrodes, recording electrodes, or both. In at least
some embodiments, the lead 110 is rotatable so that the stimulation
electrodes can be aligned with the target neurons after the neurons
have been located using the recording electrodes.
[0030] Stimulation electrodes may be disposed on the circumference
of the lead 110 to stimulate the target neurons. Stimulation
electrodes may be ring-shaped so that current projects from each
electrode equally in every direction from the position of the
electrode along a length of the lead 110. Ring electrodes, however,
typically do not enable stimulus current to be directed to only one
side of the lead. Segmented electrodes, however, can be used to
direct stimulus current to one side, or even a portion of one side,
of the lead. When segmented electrodes are used in conjunction with
an implantable pulse generator that delivers constant current
stimulus, current steering can be achieved to more precisely
deliver the stimulus to a position around an axis of the lead
(i.e., radial positioning around the axis of the lead).
[0031] To achieve current steering, segmented electrodes can be
utilized in addition to, or as an alternative to, ring electrodes.
Though the following description discusses stimulation electrodes,
it will be understood that all configurations of the stimulation
electrodes discussed may be utilized in arranging recording
electrodes as well.
[0032] The lead 100 includes a lead body 110, one or more optional
ring electrodes 120, and a plurality of sets of segmented
electrodes 130. The lead body 110 can be formed of a biocompatible,
non-conducting material such as, for example, a polymeric material.
Suitable polymeric materials include, but are not limited to,
silicone, polyurethane, polyurea, polyurethane-urea, polyethylene,
or the like. Once implanted in the body, the lead 100 may be in
contact with body tissue for extended periods of time. In at least
some embodiments, the lead 100 has a cross-sectional diameter of no
more than 1.5 mm and may be in the range of 1 to 1.5 mm. In at
least some embodiments, the lead 100 has a length of at least 10 cm
and the length of the lead 100 may be in the range of 25 to 70
cm.
[0033] The electrodes may be made using a metal, alloy, conductive
oxide, or any other suitable conductive biocompatible material.
Examples of suitable materials include, but are not limited to,
platinum, platinum iridium alloy, iridium, titanium, tungsten,
palladium, palladium rhodium, or the like. Preferably, the
electrodes are made of a material that is biocompatible and does
not substantially corrode under expected operating conditions in
the operating environment for the expected duration of use.
[0034] Each of the electrodes can either be used or unused (OFF).
When the electrode is used, the electrode can be used as an anode
or cathode and carry anodic or cathodic current. In some instances,
an electrode might be an anode for a period of time and a cathode
for a period of time.
[0035] Stimulation electrodes in the form of ring electrodes 120
may be disposed on any part of the lead body 110, usually near a
distal end of the lead 100. In FIG. 1, the lead 100 includes two
ring electrodes 120. Any number of ring electrodes 120 may be
disposed along the length of the lead body 110 including, for
example, one, two three, four, five, six, seven, eight, nine, ten,
eleven, twelve, thirteen, fourteen, fifteen, sixteen or more ring
electrodes 120. It will be understood that any number of ring
electrodes may be disposed along the length of the lead body 110.
In some embodiments, the ring electrodes 120 are substantially
cylindrical and wrap around the entire circumference of the lead
body 110. In some embodiments, the outer diameters of the ring
electrodes 120 are substantially equal to the outer diameter of the
lead body 110. The length of the ring electrodes 120 may vary
according to the desired treatment and the location of the target
neurons. In some embodiments the length of the ring electrodes 120
are less than or equal to the diameters of the ring electrodes 120.
In other embodiments, the lengths of the ring electrodes 120 are
greater than the diameters of the ring electrodes 120.
[0036] Deep brain stimulation leads may include one or more sets of
segmented electrodes. Segmented electrodes may provide for superior
current steering than ring electrodes because target structures in
deep brain stimulation are not typically symmetric about the axis
of the distal electrode array. Instead, a target may be located on
one side of a plane running through the axis of the lead. Through
the use of a radially segmented electrode array ("RSEA"), current
steering can be performed not only along a length of the lead but
also around a circumference of the lead. This provides precise
three-dimensional targeting and delivery of the current stimulus to
neural target tissue, while potentially avoiding stimulation of
other tissue.
[0037] In FIG. 1, the lead 100 is shown having a plurality of
segmented electrodes 130. Any number of segmented electrodes 130
may be disposed on the lead body 110 including, for example, one,
two three, four, five, six, seven, eight, nine, ten, eleven,
twelve, thirteen, fourteen, fifteen, sixteen or more segmented
electrodes 130. It will be understood that any number of segmented
electrodes 130 may be disposed along the length of the lead body
110.
[0038] The segmented electrodes 130 may be grouped into sets of
segmented electrodes, where each set is disposed around a
circumference of the lead 100 at a particular longitudinal portion
of the lead 100. The lead 100 may have any number segmented
electrodes 130 in a given set of segmented electrodes. The lead 100
may have one, two, three, four, five, six, seven, eight, or more
segmented electrodes 130 in a given set. In at least some
embodiments, each set of segmented electrodes 130 of the lead 100
contains the same number of segmented electrodes 130. The segmented
electrodes 130 disposed on the lead 100 may include a different
number of electrodes than at least one other set of segmented
electrodes 130 disposed on the lead 100.
[0039] The segmented electrodes 130 may vary in size and shape. In
some embodiments, the segmented electrodes 130 are all of the same
size, shape, diameter, width or area or any combination thereof. In
some embodiments, the segmented electrodes 130 of each
circumferential set (or even all segmented electrodes disposed on
the lead 100) may be identical in size and shape.
[0040] Each set of segmented electrodes 130 may be disposed around
the circumference of the lead body 110 to form a substantially
cylindrical shape around the lead body 110. The spacing between
individual electrodes of a given set of the segmented electrodes
may be the same, or different from, the spacing between individual
electrodes of another set of segmented electrodes on the lead 100.
In at least some embodiments, equal spaces, gaps or cutouts are
disposed between each segmented electrode 130 around the
circumference of the lead body 110. In other embodiments, the
spaces, gaps or cutouts between the segmented electrodes 130 may
differ in size or shape. In other embodiments, the spaces, gaps, or
cutouts between segmented electrodes 130 may be uniform for a
particular set of the segmented electrodes 130, or for all sets of
the segmented electrodes 130. The sets of segmented electrodes 130
may be positioned in irregular or regular intervals along a length
the lead body 110.
[0041] Conductor wires that attach to the ring electrodes 120 or
segmented electrodes 130 extend along the lead body 110. These
conductor wires may extend through the material of the lead 100 or
along one or more lumens defined by the lead 100, or both. The
conductor wires are presented at a connector (via terminals) for
coupling of the electrodes 120, 130 to a control unit (not
shown).
[0042] When the lead 100 includes both ring electrodes 120 and
segmented electrodes 130, the ring electrodes 120 and the segmented
electrodes 130 may be arranged in any suitable configuration. For
example, when the lead 100 includes two sets of ring electrodes 120
and two sets of segmented electrodes 130, the ring electrodes 120
can flank the two sets of segmented electrodes 130 (see e.g., FIG.
1). Alternately, the two sets of ring electrodes 120 can be
disposed proximal to the two sets of segmented electrodes 130 (see
e.g., FIG. 3C), or the two sets of ring electrodes 120 can be
disposed distal to the two sets of segmented electrodes 130 (see
e.g., FIG. 3D). It will be understood that other configurations are
possible as well (e.g., alternating ring and segmented electrodes,
or the like).
[0043] By varying the location of the segmented electrodes 130,
different coverage of the target neurons may be selected. For
example, the electrode arrangement of FIG. 3C may be useful if the
physician anticipates that the neural target will be closer to a
distal tip of the lead body 110, while the electrode arrangement of
FIG. 3D may be useful if the physician anticipates that the neural
target will be closer to a proximal end of the lead body 110.
[0044] Any combination of ring electrodes 120 and segmented
electrodes 130 may be disposed on the lead 100. For example, the
lead may include a first ring electrode 120, two sets of segmented
electrodes; each set formed of four segmented electrodes 130, and a
final ring electrode 120 at the end of the lead. This configuration
may simply be referred to as a 1-4-4-1 configuration. It may be
useful to refer to the electrodes with this shorthand notation.
Thus, the embodiment of FIG. 3C may be referred to as a 1-1-4-4
configuration, while the embodiment of FIG. 3D may be referred to
as a 4-4-1-1 configuration. Other electrode configurations include,
for example, a 2-2-2-2 configuration, where four sets of segmented
electrodes are disposed on the lead, and a 4-4 configuration, where
two sets of segmented electrodes, each having four segmented
electrodes 130 are disposed on the lead. In some embodiments, the
lead includes 16 electrodes. Possible configurations for a
16-electrode lead include, but are not limited to 4-4-4-4; 8-8;
3-3-3-3-3-1 (and all rearrangements of this configuration); and
2-2-2-2-2-2-2-2.
[0045] FIG. 2 is a schematic diagram to illustrate radial current
steering along various electrode levels along the length of the
lead 200. While conventional lead configurations with ring
electrodes are only able to steer current along the length of the
lead (the z-axis), the segmented electrode configuration is capable
of steering current in the x-axis, y-axis as well as the z-axis.
Thus, the centroid of stimulation may be steered in any direction
in the three-dimensional space surrounding the lead 200. In some
embodiments, the radial distance, r, and the angle .theta. around
the circumference of the lead 200 may be dictated by the percentage
of anodic current (recognizing that stimulation predominantly
occurs near the cathode, although strong anodes may cause
stimulation as well) introduced to each electrode. In at least some
embodiments, the configuration of anodes and cathodes along the
segmented electrodes allows the centroid of stimulation to be
shifted to a variety of different locations along the lead 200.
[0046] As can be appreciated from FIG. 2, the centroid of
stimulation can be shifted at each level along the length of the
lead 200. The use of multiple sets of segmented electrodes at
different levels along the length of the lead allows for
three-dimensional current steering. In some embodiments, the sets
of segmented electrodes are shifted collectively (i.e., the
centroid of simulation is similar at each level along the length of
the lead). In at least some other embodiments, each set of
segmented electrodes is controlled independently. Each set of
segmented electrodes may contain two, three, four, five, six,
seven, eight or more segmented electrodes. It will be understood
that different stimulation profiles may be produced by varying the
number of segmented electrodes at each level. For example, when
each set of segmented electrodes includes only two segmented
electrodes, uniformly distributed gaps (inability to stimulate
selectively) may be formed in the stimulation profile. In some
embodiments, at least three segmented electrodes 230 in a set are
utilized to allow for true 360.degree. selectivity.
[0047] As previously indicated, the foregoing configurations may
also be used while utilizing recording electrodes. In some
embodiments, measurement devices coupled to the muscles or other
tissues stimulated by the target neurons or a unit responsive to
the patient or clinician can be coupled to the control unit or
microdrive motor system. The measurement device, user, or clinician
can indicate a response by the target muscles or other tissues to
the stimulation or recording electrodes to further identify the
target neurons and facilitate positioning of the stimulation
electrodes. For example, if the target neurons are directed to a
muscle experiencing tremors, a measurement device can be used to
observe the muscle and indicate changes in tremor frequency or
amplitude in response to stimulation of neurons. Alternatively, the
patient or clinician may observe the muscle and provide
feedback.
[0048] The reliability and durability of the lead will depend
heavily on the design and method of manufacture. Fabrication
techniques discussed below provide methods that can produce
manufacturable and reliable leads.
[0049] Returning to FIG. 1, when the lead 100 includes a plurality
of sets of segmented electrodes 130, it may be desirable to form
the lead 100 such that corresponding electrodes of different sets
of segmented electrodes 130 are radially aligned with one another
along the length of the lead 100 (see e.g., the segmented
electrodes 130 shown in FIG. 1). Radial alignment between
corresponding electrodes of different sets of segmented electrodes
130 along the length of the lead 100 may reduce uncertainty as to
the location or orientation between corresponding segmented
electrodes of different sets of segmented electrodes. Accordingly,
it may be beneficial to form electrode arrays such that
corresponding electrodes of different sets of segmented electrodes
along the length of the lead 100 are radially aligned with one
another and do not radially shift in relation to one another during
manufacturing of the lead 100.
[0050] In other embodiments, individual electrodes in the two sets
of segmented electrodes 130 are staggered relative to one another
along the length of the lead body 110. In some cases, the staggered
positioning of corresponding electrodes of different sets of
segmented electrodes along the length of the lead 100 may be
designed for a specific application.
[0051] Segmented electrodes can be used to tailor the stimulation
region so that, instead of stimulating tissue around the
circumference of the lead as would be achieved using a ring
electrode, the stimulation region can be directionally targeted. In
some instances, it is desirable to target a parallelepiped (or
slab) region 250 that contains the electrodes of the lead 200, as
illustrated in FIG. 2. One arrangement for directing a stimulation
field into a parallelepiped region uses segmented electrodes
disposed on opposite sides of a lead.
[0052] FIGS. 3A-3D illustrate leads 300 with segmented electrodes
330, optional ring electrodes 320, and a lead body 310. The groups
of segmented electrodes 330 include either two (FIG. 3B) or four
(FIGS. 3A, 3C, and 3D) segmented electrodes. It will be recognized
that other groups of segmented electrodes with an even number of
electrodes in the group can also be used. In these embodiments,
segmented electrodes on opposite sides of the lead are ganged
(i.e., electrically coupled) together, as illustrated schematically
by the lines 360.
[0053] One arrangement for ganging two segmented electrodes
together which includes coupling the two electrodes (for example,
electrodes 330a and 330b) using a conductor (represented by line
360) that passes through the lead body. This conductor (represented
by line 360) can be coupled to another conductor (not shown) that
passes through the lead body to the proximal end of the lead to
provide for connection to a terminal or contact at the proximal end
of the lead. Alternatively, one electrode (for example, electrode
330a) is electrically coupled to a conductor (not shown) that
passes through the lead body to the proximal end of the lead to
provide for connection to a terminal or contact at the proximal end
of the lead and the other electrode (for example, electrode 330b)
is coupled to the first electrode by the conductor represented by
line 360. This conductor might be a wire or may be a thin, flat
conductor.
[0054] In operation, stimulation current is applied through the
ganged segmented electrodes (for example, electrodes 330a and
330b). For example, the ganged segmented electrodes can operate as
cathodes. In some embodiments, other ganged electrodes (for
example, electrodes 330c and 330d) may be assigned the opposite
polarity (for example, as anodes) which may further direct the
stimulation field into the desired parallelepiped region.
[0055] As illustrated in FIGS. 3A, 3C, and 3D, multiple pairs of
ganged segmented electrodes 330 can be provided in each group of
segmented electrodes. The pairs of ganged segmented electrodes 330
are radially offset from each other. For example, two pairs may be
radially offset by an angle in the range of 75 to 115 degrees or by
an angle in the range of 80 to 110 degrees or be an angle of 90
degrees.
[0056] As illustrated in FIG. 3B, the pairs of ganged segmented
electrodes can be longitudinally staggered with respect to each
other. As illustrated in FIG. 3B, the staggered pairs of ganged
segmented electrodes may include electrode portions that are at a
same longitudinal position (i.e., the two pairs overlap
longitudinally--but not radially). In other embodiments, the
electrodes of the staggered pairs do not overlap longitudinally
(i.e., no portions of the electrodes of the two pairs have the same
longitudinal position on the lead).
[0057] Any other suitable arrangements of segmented electrodes (and
pairs of ganged segmented electrodes) can be used. As an example,
arrangements in which pairs of segmented electrodes are arranged
helically with respect to each other. One embodiment includes a
double helix with the electrodes at each longitudinal position
along the two helices ganged together.
[0058] As an alternative to ganging segmented electrodes together
using conductors, the segmented electrodes (or a subset of
segmented electrodes) can be coupled to a multiplexer (which is
preferably disposed in the lead near the electrodes) or to
controllable switches (which are preferably disposed in the lead
near the electrodes). The multiplexer or controllable switches can
be used to electrically gang segmented electrodes together, but can
also be used to change which electrodes are ganged together, if
desired.
[0059] Other lead configurations can also be used. For example,
FIGS. 4A and 4B illustrate portions of a lead 400 with a lead body
410 having a non-circular cross-section and including two elongated
surfaces upon which electrodes 430 are disposed. This lead 400 is
sized so that it can be implanted percutaneously using an
introducer 470 such as a percutaneous needle or cannula.
[0060] The lead body 410 can have any suitable non-circular
cross-sectional shape including, but not limited to, oval,
rectangular, square, or rectangular/square with rounded corners (as
illustrated in FIG. 4), or the like. In some embodiments, the
non-circular cross-sectional shape of the lead extends the entire
length of the lead. In other embodiments, the non-circular
cross-sectional shape of the lead only extends a portion (for
example, a portion including the region near the distal end upon
which the electrodes are disposed) of the length of the lead with
the remainder of the lead having a circular cross-sectional shape
(for example, a portion including the proximal end of the
lead).
[0061] The lead body 410 has two opposing surfaces upon which
electrodes 430 can be disposed. These surfaces may be flat or
curved. The electrodes are coupled to terminals (not shown) on the
proximal end of the lead by conductors (not shown) that extend
along the length of the lead.
[0062] The electrodes can be formed using any biocompatible
conductive material. Examples of suitable materials include metals,
alloys, conductive polymers, conductive carbon, and the like, as
well as combinations thereof. In at least some embodiments, one or
more of the electrodes are formed from one or more of: platinum,
platinum iridium, palladium, titanium nitride, or rhenium.
[0063] The electrodes 430 can be disposed in an array on each of
the surfaces of the lead, as illustrated in FIG. 4B. The number of
electrodes 430 in the array of electrodes on a particular surface
of the lead may vary. For example, there can be two, three, four,
five, six, seven, eight, nine, ten, eleven, twelve, thirteen,
fourteen, fifteen, sixteen, or more electrodes. As will be
recognized, other numbers of electrodes may also be used. The
electrodes 140 can be formed in any suitable shape including, for
example, round, oval, triangular, rectangular, pentagonal,
hexagonal, heptagonal, octagonal, or the like. The electrodes 430
of an array can be arranged in any arrangement including
arrangements with in one or more columns, one or more rows, or both
rows and columns (as illustrated in FIG. 4B). The electrodes 430 in
a row or column may be aligned with an adjacent row or column or
may be staggered with respect to an adjacent row or column. There
may be an array of electrodes 430 on two opposing sides of lead
400, as illustrated in FIG. 4A. The arrays on the two opposing
sides can be the same or different.
[0064] The electrodes 430 are typically disposed in, or separated
by, a non-conductive, biocompatible material of the lead body 410
including, for example, silicone, polyurethane, and the like or
combinations thereof. The lead body 410 may be formed in the
desired shape by any process including, for example, molding
(including injection molding), casting, and the like. Electrodes
and connecting wires can be disposed onto or within the lead body
either prior to or subsequent to a molding or casting process.
[0065] In some embodiments, electrodes 430 on opposite sides (and,
preferably, directly opposite each other) of the lead body 410 can
be ganged together in a manner similar to that illustrated for the
embodiments of FIGS. 3A-3D. In some embodiments, electrodes 430 on
the same side of the lead body 410 (for example, electrodes in a
row or column) can be ganged together.
[0066] A lead with a lead body having a non-circular
cross-sectional shape and electrodes disposed thereon can be formed
using an suitable technique including forming a lead body around
electrodes disposed in two sides of a mold. In at least some
instances, it may be easier or more economical to form electrodes
on one side of a lead body. FIGS. 6A and 6B illustrate one method
for forming a lead body 610 having a non-circular cross-sectional
shape and electrodes 630 disposed on opposing sides of the lead
body. As illustrated in FIG. 6A, a lead body 610 with electrodes
630 disposed on one side of the lead body is formed. For example,
the electrodes 630 can be attached to conductors (not shown) which
can extend along the lead to terminals or contact on a distal end
of the lead. These electrodes 630 can be placed in a mold and then
the lead body 610 molded around the electrodes 630 leaving a
surface of each electrode exposed.
[0067] In these embodiments, the lead body 610 includes two main
portions 612 divided by a bendable portion 614. The electrodes are
disposed on the two main portions 612. In at least some
embodiments, the bendable portion 614 has a thickness that is
substantially less than a thickness of the two main portions. In
some embodiments, the bendable portion 612 may include one or more
hinges, one or more holes, one or more reduced-thickness portion,
or any other suitable structure that facilitates bending or folding
of the bendable portion.
[0068] In forming the lead with electrodes on opposing sides, the
bendable portion 614 is bent so that the two main portions 612 are
disposed opposite each other, as illustrated in FIG. 6B. This lead
body 610 can be inserted into an introducer 670. In some
embodiments, the bendable portion 614 contains material that
retains the bend once bent. In other embodiments, the bendable
portion 614 is resilient and may spring back to its original shape
or some intermediate position. Optionally, one or more fasteners
(e.g., straps, hooks, and the like), sutures disposed around the
lead body, or adhesive may be provided to retain the lead body 610
in the bent shape. In other embodiments, the lead body 610 retains
the bent shape once implanted due to the presence of adjacent
tissue.
[0069] When implanting a lead, particularly in the brain, it can be
useful to provide a recording electrode that can be used to
identify the tissue that is to be stimulated. In many conventional
procedures, a recording electrode lead is inserted into an
introducer and the introducer is inserted into the patient. The
introducer is then moved through the tissue using the recording
electrode to identify which tissue is to be stimulated. Once the
desired tissue is identified, the recording electrode lead is
removed from the introducer and a stimulating electrode lead is
inserted. This conventional procedure can take additional time for
removal and insertion of multiple leads. Moreover, the introducer
may inadvertently move during removal of the recording electrode
lead and the insertion of the stimulating electrode lead which may
result in the stimulating electrode lead being no longer aligned
with the desired tissue.
[0070] A system can be provided that addresses this issue by
providing an introducer and lead that can be used simultaneously
with a microelectrode lead. FIG. 5 illustrates one embodiment of
such a system with an introducer 570 (e.g., a cannula or a needle)
defining an introducer lumen 572 into which a stimulation lead 500
(which can correspond to the lead 400 of FIGS. 4A and 4B) can be
inserted. Within the introducer lumen 572, one or more
microelectrode lumens 574 are formed using one or more walls 582.
FIG. 5 illustrates two microelectrode lumens, but in other
embodiments only one microelectrode lumen is provided. A
microelectrode lead 580 can be inserted with each microelectrode
lumen 574 formed within the introducer 570. The microelectrode lead
580 includes a microelectrode at a tip of the microelectrode lead
580 which can be used as a recording electrode to identify tissue
to be stimulated. The microelectrode lead 580 may be, for example,
a guidewire or other suitable lead structure.
[0071] The walls 582 which form the microelectrode lumens 574 can
be cylindrical or any other suitable shape. The walls 582 surround
the entire lumen (e.g., have a circular cross-section) or may
include openings (for example, have a C-shape in cross-section, as
illustrated in FIG. 5). In some instances, a portion of the wall of
the introducer may form part of the wall 582 of the microelectrode
lumens 574. The walls 582 may extend the entire length of the
introducer 570 or may only extend partway along the introducer, for
example, partway from the distal end or the proximal end or a
combination thereof.
[0072] The arrangement illustrated in FIG. 5 allows for the
introducer 570 to contain both the microelectrodes lead(s) 580 and
the stimulation lead 500 simultaneously. In some embodiments, both
the microelectrode lead(s) 580 and stimulation lead are inserted
into the introducer prior to insertion of the introducer into the
patient. In other embodiments, the microelectrode lead(s) may be
inserted into the introducer prior to, or after, insertion of the
introducer into the patient and then the microelectrode lead(s) are
used to identify the tissue to be stimulated. Later, the
stimulation lead may be inserted into the introducer with the
microelectrode lead(s) remaining in the introducer. The
microelectrode lead(s) can be used to verify that the stimulation
lead is properly positioned after it insertion into the introducer
in the patient.
[0073] The above specification, examples, and data provide a
description of the manufacture and use of the composition of the
invention. Since many embodiments of the invention can be made
without departing from the spirit and scope of the invention, the
invention also resides in the claims hereinafter appended.
* * * * *