U.S. patent application number 16/543308 was filed with the patent office on 2019-12-05 for directional electrode devices with locating features.
The applicant listed for this patent is Intelect Medical Inc.. Invention is credited to Keith Carlton, Alan Greszler, Scott Kokones.
Application Number | 20190366074 16/543308 |
Document ID | / |
Family ID | 40532482 |
Filed Date | 2019-12-05 |
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United States Patent
Application |
20190366074 |
Kind Code |
A1 |
Carlton; Keith ; et
al. |
December 5, 2019 |
DIRECTIONAL ELECTRODE DEVICES WITH LOCATING FEATURES
Abstract
Electrode devices having directional electrodes for use in deep
brain stimulation or other uses. In one aspect, an electrode
assembly comprises an elongate lead and a lead guide that are
engageable with each other in a coaxial relationship. When the
elongate lead and the lead guide are engaged with each other, the
two components are rotationally fixed in relation to each other. In
another aspect, an elongate lead comprises a radiologically-visible
feature for indicating the orientation of the elongate lead. In yet
another aspect, an electrode system is capable of determining the
position and/or orientation of an electrode positioned within a
body. In other aspects, methods for electrically stimulating a
target site in the body are disclosed.
Inventors: |
Carlton; Keith; (Boston,
MA) ; Greszler; Alan; (Bay Village, OH) ;
Kokones; Scott; (Boston, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intelect Medical Inc. |
Marlborough |
MA |
US |
|
|
Family ID: |
40532482 |
Appl. No.: |
16/543308 |
Filed: |
August 16, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14943857 |
Nov 17, 2015 |
10434302 |
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16543308 |
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12029141 |
Feb 11, 2008 |
9220889 |
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14943857 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/0551 20130101;
A61N 1/0534 20130101; A61N 1/0539 20130101; A61N 1/0529 20130101;
A61N 1/36182 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05; A61N 1/36 20060101 A61N001/36 |
Claims
1. An elongate lead having a distal portion and longitudinal axis,
the elongate lead comprising: at least one directional electrode
disposed on the distal portion of the elongate lead, wherein each
of the at least one directional electrode extends less than 360
degrees around the elongate lead; and an orientation indicator
positioned and aligned with an orientation of one of the at least
one directional electrode.
2. The elongate lead of claim 1, wherein the orientation indicator
comprises a first portion and a second portion, wherein the first
portion has a larger width than the second portion.
3. The elongate lead of claim 2, wherein the first portion is
proximal to the second portion.
4. The elongate lead of claim 1, wherein the at least one
directional electrode comprises two directional electrodes disposed
at a same longitudinal position relative to the longitudinal axis
of the elongate lead, wherein the two directional electrodes do not
overlap with each other, wherein the orientation indictor is
aligned with the orientation of only one of the two directional
electrodes.
5. The elongate lead of claim 1, further comprising at least one
cylindrical electrode disposed on the distal portion of the
elongate lead and extending 360 degrees around the elongate
lead.
6. The elongate lead of claim 1, wherein the at least one
directional electrode comprises at least two directional electrodes
disposed at different longitudinal positions relative to the
longitudinal axis of the elongate lead, wherein the at least two
directional electrodes do not overlap with each other, wherein the
orientation indictor is aligned with the orientation of at least
one of the at least two directional electrodes.
7. The elongate lead of claim 1, wherein each of the at least one
directional electrode extends no more than 120 degrees around the
elongate lead.
8. A method for implanting the elongate lead of claim 1, the method
comprising: introducing the elongate lead into a patient using a
lead guide; and determining an orientation of the at least one
directional electrode of the elongate lead using the orientation
indicator.
9. The method of claim 8, wherein the lead guide comprises a
cannula.
10. The method of claim 8, wherein the lead guide comprises a
stylet.
11. The method of claim 8, further comprising rotating the elongate
lead to position the at least one directional electrode in a
desired orientation.
12. The method of claim 8, wherein the orientation indicator
comprises a first portion and a second portion, wherein the first
portion has a larger width than the second portion.
13. The method of claim 12, wherein the first portion is proximal
to the second portion.
14. The method of claim 8, wherein the at least one directional
electrode comprises two directional electrodes disposed at a same
longitudinal position relative to the longitudinal axis of the
elongate lead, wherein the two directional electrodes do not
overlap with each other, wherein the orientation indictor is
aligned with the orientation of only one of the two directional
electrodes.
15. The method of claim 8, wherein the elongate lead further
comprises at least one cylindrical electrode disposed on the distal
portion of the elongate lead and extending 360 degrees around the
elongate lead.
16. The method of claim 8, wherein the at least one directional
electrode comprises at least two directional electrodes disposed at
different longitudinal positions relative to the longitudinal axis
of the elongate lead, wherein the at least two directional
electrodes do not overlap with each other, wherein the orientation
indictor is aligned with the orientation of at least one of the at
least two directional electrodes.
17. The method of claim 8, wherein each of the at least one
directional electrode extends no more than 120 degrees around the
elongate lead.
18. An electrode assembly, comprising the elongate lead of claim 1;
and a lead guide.
19. The electrode assembly of claim 18, wherein the lead guide
comprises a cannula.
20. The electrode assembly of claim 18, wherein the lead guide
comprises a stylet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/943,857, filed Nov. 17, 2015, which is a
divisional of U.S. patent application Ser. No. 12/029,141 filed
Feb. 11, 2008, both of which are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] The present invention relates to medical devices, and in
particular, electrode devices for electrical stimulation.
BACKGROUND
[0003] Implantable pulse generators for stimulating tissue are
being used in increasing numbers to treat a wide variety of medical
conditions. In many cases, electrical stimulation pulses are
conveyed from a pulse generator to a desired stimulation site by an
implanted lead with exposed electrodes. In order to achieve the
desired effects from the delivery of stimulating pulses, it is
important that the lead is properly positioned so that optimal
stimulating energy is applied to a desired site. While this is true
for many different kinds of stimulation therapies, lead positioning
is especially critical in the area of neurological stimulation.
[0004] Stylets are used in the field of electrical stimulation for
guiding and properly placing leads. Leads that utilize stylets for
guidance are subject to the problem of lead twisting or torquing
during placement. Lead twisting or torquing often results in the
lead rotating with respect to the stylet and possibly becoming
misaligned. Precise knowledge of the location and position of the
lead and electrodes providing the stimulation, along with its
volume of activation relative to the target site and surrounding
structures is critical to treatments, particularly when providing
neurological stimulation to an area of a patient's brain.
[0005] While conventional DBS systems have advanced rehabilitation
and treatment in a number of areas, certain challenges remain and
there is a need for electrode devices to meet these challenges.
SUMMARY
[0006] In a first aspect, the present invention provides an
electrode assembly comprising: (a) an elongate lead having at least
one directional electrode positioned at a distal portion thereof;
and (b) a lead guide that is slidably engageable with the elongate
lead in a coaxial relationship. The elongate lead and the lead
guide are rotationally fixed when they are engaged with each
other.
[0007] In a second aspect, the present invention provides an
elongate lead comprising: (a) at least one directional stimulation
electrode positioned on a distal portion of the elongate lead; and
(b) at least one radiologically-visible feature for indicating the
orientation of the at least one directional stimulation electrode
when viewed under radiologic imaging.
[0008] In a third aspect, the present invention provides an
electrode system comprising: (a) an elongate lead having at least
one directional electrode positioned at a distal portion of the
elongate lead; and (b) a position determining apparatus for
determining the position and/or orientation of the at least one
directional electrode when the electrode is positioned in a
body.
[0009] In other aspects, the present invention provides methods for
electrically stimulating a target site in the body using various
electrode devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A-1D show various views of an electrode assembly
according to an embodiment of the present invention. FIG. 1A shows
a side view of an elongate lead. FIG. 1B shows a side view of a
stylet. FIG. 1C shows a side view of the elongate lead with the
stylet inserted therein. FIG. 1D shows a transverse cross-section
view of the assembly taken at arrow 1 in FIG. 1C.
[0011] FIGS. 2A and 2B show a stylet according to another
embodiment. FIG. 2A shows a perspective view of the stylet. FIG. 2B
shows a distal end view of the stylet.
[0012] FIGS. 3A and 3B show an electrode assembly according to
another embodiment.
[0013] FIG. 3A shows a partial cross-section side view of the
electrode assembly with an elongate lead inserted within a cannula.
FIG. 3B shows a transverse cross-section view of the assembly taken
at arrow 2 in FIG. 3A.
[0014] FIG. 4 shows a transverse cross-section view of an electrode
assembly according to yet another embodiment.
[0015] FIG. 5 shows a perspective view of a cannula holder
according to an embodiment.
[0016] FIGS. 6A-6E show transverse cross-sections views of a stylet
according to various alternate embodiments of the electrode
assembly.
[0017] FIGS. 7A-7C show an electrode assembly according to yet
another embodiment.
[0018] FIG. 7A shows a partial cross-section side view of the
assembly. FIG. 7B shows a transverse cross-section view of the
assembly taken at arrow 3 in FIG. 7A, with the gripping elements in
a released position. FIG. 7C shows a transverse cross-section view
of the assembly taken at arrow 3 in FIG. 7A, with the gripping
elements in a gripping position.
[0019] FIG. 8 shows a transverse cross-section view of an electrode
assembly according to yet another embodiment.
[0020] FIGS. 9A and 9B show side views of an elongate lead
according to an embodiment of the present invention. FIG. 9A shows
the elongate lead with the radiopaque feature facing out of the
page. FIG. 9B shows the elongate lead rotated 180.degree. from the
view shown in FIG. 9A such that the radiopaque feature faces into
the page.
[0021] FIGS. 10A and 10B show side views of an elongate lead
according to another embodiment. FIG. 10A shows the elongate lead
with the radiopaque feature facing out of the page. FIG. 10B shows
the elongate lead rotated 180.degree. from the view shown in FIG.
10A such that the radiopaque feature faces into the page.
[0022] FIGS. 11A and 11B show side views of an elongate lead
according to yet another embodiment. FIG. 11A shows the elongate
lead with the radiopaque feature facing out of the page. FIG. 11B
shows the elongate lead rotated 180.degree. from the view shown in
FIG. 11A such that the radiopaque feature faces into the page.
[0023] FIGS. 12A and 12B show side views of an elongate lead having
a radiopaque feature that is symmetric with respect to the central
longitudinal axis of the elongate lead. FIG. 12A shows the elongate
lead with the radiopaque feature facing out of the page. FIG. 12B
shows the elongate lead rotated 180.degree. from the view shown in
FIG. 12A such that the radiopaque feature faces into the page.
[0024] FIGS. 13A and 13B show side views of an elongate lead
according to yet another embodiment. FIG. 13A shows the elongate
lead in a straight configuration. FIG. 13B shows the elongate lead
in a twisted configuration.
[0025] FIGS. 14A and 14B show side views of an elongate lead
according to yet another embodiment. FIG. 14A shows the elongate
lead in one rotational orientation; and FIG. 14B shows the elongate
lead rotated 180.degree. from the view shown in FIG. 14A.
[0026] FIG. 15 shows an electrode system according to an embodiment
of the present invention.
[0027] FIG. 16 shows a flowchart illustrating the processes
performed by software within an electrode system according to yet
another embodiment.
DETAILED DESCRIPTION
[0028] In an embodiment, the present invention provides methods,
systems and devices for the accurate placement of leads in the
brain and/or other parts of the nervous system. In a first aspect,
the present invention provides an electrode assembly comprising a
first component which is an elongate lead having at least one
directional electrode positioned at a distal portion thereof. As
used herein, a "directional electrode" refers to an electrode on an
elongate lead in which the electrode extends less than 360.degree.
about the body of the elongate lead. The assembly further includes
a second component that is a lead guide that is slidably engageable
with the elongate lead in a coaxial relationship. Accordingly, the
elongate lead may have an inner channel with the lead guide being
insertable into the inner channel of the elongate lead; or
alternatively, the lead guide may have an inner channel with the
elongate lead being insertable into the inner channel of the lead
guide. According to this embodiment, the elongate lead and the lead
guide are rotationally fixed when they are engaged with one
another. As used herein, the term "rotation," when used in relation
to the elongate lead or the lead guide, refers to rotation about
the central longitudinal axis of the component. By being
rotationally fixed in relation to each other, rotation of the lead
guide will cause rotation of the elongate lead, and vice versa.
Similarly, if the lead guide is not rotated, this will cause
non-rotation of the elongate lead. Accordingly, the elongate lead
and the lead guide, although separate components, rotate as a
single unit. Since the lead guide is designed to transfer any
rotational torque (e.g., provided manually or by other means by the
user at the proximal end of the lead guide) to the elongate lead,
the lead guide may have any of various features for facilitating
this function, such as handles and alignment markers indicating the
alignment of the two components.
[0029] The rotational fixation between the elongate lead and the
lead body may be achieved by any of various mechanisms to restrain
rotational movement of the elongate lead in relation to the lead
guide. Such mechanisms permit a rotational force placed on the
proximal end of the lead guide to be transferred along the length
of the lead thereby causing the proximal and distal ends of the
lead to rotate together in unison. Non-limiting examples of locking
mechanisms to achieve this restraint in rotational movement,
include male/female connections, threadable engagement, or
interference fit. In certain embodiments, the elongate lead
comprises a first rotation locking structure, and the lead guide
comprises a second rotation locking structure. The first rotation
locking structure and the second rotation locking structure
releasably engage and cooperate with each other to restrain
rotational movement of the elongate lead in relation to the lead
guide. The rotation locking structures may be located on any of
various portions of the elongate lead or lead guide, including
inner surfaces, outer surfaces, distal portions, or proximal
portions so long as torque is transferred to the elongate lead when
the lead guide is rotated. Therefore, lead guide and the elongate
lead can be configured to be mated such that rotation of the
proximal end of the lead guide causes the proximal and distal ends
of the elongate lead to also rotate.
[0030] In some embodiments, the first rotation locking structure
and the second rotation locking structure have complementary
geometries (i.e. a male/female relationship), allowing a mating
interaction between the two locking structures. For example, one
component (i.e., the lead guide or the elongate lead) can have a
protruding structure and the other component can have a recessed
structure, wherein the protruding structure interlocks with the
recessed structure in such a way as to limit rotational movement of
the elongate lead relative to the lead guide. The protruding
structures may be, for example, ridges, bumps, ribs, and the like.
The recessed structure may be, for example, grooves, channels,
pits, cavities, and the like. The female structure can either be
part of the elongate guide or the lead body. Similarly, the male
structure can be part of the elongate guide or the lead body.
Furthermore, the locking structures can either be made of a
separate material than the component to which they are a part of or
they can be made of the same material. As such, the locking
structures and their respective component can form a single unitary
structure or the two can be separate elements that are coupled
together.
[0031] For example, referring to the embodiment shown in FIGS.
1A-1D, an electrode assembly 10 comprises an elongate lead 20 and a
lead guide in the form of stylet 16. In this embodiment, elongate
lead 20 has directional stimulation electrodes 22 positioned at a
distal portion of elongate lead 20. As seen in FIG. 1D, directional
electrodes 22 extend 120.degree. about the body of elongate lead
20, however, the directional electrode can extend any degree about
the body of lead 20 that is less than 360.degree.. Elongate lead 20
also has electrical contacts 24 for coupling with an external
stimulator or implantable pulse generator. Each of contacts 24
independently supply electrical connectivity to electrodes 22.
Elongate lead 20 has an inner channel 30 which is configured to
receive stylet 16. Stylet 16 is made of a relatively stiff material
and is configured to be inserted within inner channel 30 of
elongate lead 20. In this embodiment, the first rotation locking
structure is a key 14 and is rigidly fixed onto or otherwise
integral with a distal portion of stylet 16. Inner channel 30 of
elongate lead 20 has the second locking structure, which is a
recess 32 contoured to receive key 14 in a locking secure manner
and which extends along the length of elongate lead 20. The recess
can be made of the same material as the elongate lead, such as
polyurethane, or can be a separate structure applied to the
elongate lead, such as a metal insert. A handle 18 can be fixed to
the proximal end of stylet 16 to allow the user to apply torque to
stylet 16, which is transferred throughout the length of lead 20
thereby causing the proximal and distal ends of the lead to rotate
in unison. Of course, stylet 16 could also be rotated by means
other than manual means, such as electrically or
telemetrically.
[0032] In operation, the distal end of elongate lead 20 is inserted
into the target site. Stylet 16 is inserted into inner channel 30
of elongate lead 20. To ensure alignment of key 14 and recess 32,
elongate lead 20 and stylet 16 can both have orientation
indicators, which in the embodiment shown in FIGS. 1A-1C are marks
parallel to the longitudinal axis of elongate lead 20 and stylet
16. Specifically, referring to FIGS. 1A-1C, the proximal end of
elongate lead 20 can have an orientation indicator 26 and handle 18
of stylet 16 can have an orientation indicator 19, with orientation
indicator 26 aligned with recess 32 and orientation indicator 19
aligned with key 14. When orientation indicator 26 is aligned with
orientation indicator 19, a straight line is formed, which
indicates that key 14 is aligned with recess 32. Of course, other
configurations of orientation indicators 26 and 19 are also
possible. Because of the mating of key 14 and recess 32, elongate
lead 20 is rotationally locked with stylet 16. Thus, as elongate
lead 20 is being positioned at the target site, the user can turn
handle 18 of stylet 16 to cause elongate lead 20 to rotate
accordingly, allowing the user to adjust the directional
orientation of directional electrodes 22. One or more of
directional electrodes 22 can then be activated to provide
electrical stimulation to the target site.
[0033] Other configurations for the stylet and/or key are also
possible. For example, referring to the embodiment shown in FIGS.
2A and 2B, a stylet 34 has a shaft 36 and a key 38 located at the
distal tip of shaft 36. As seen in the end-view of stylet 34 in
FIG. 2B, in this embodiment, the maximum width of key 38 is no
greater than the diameter of shaft 36. An elongate lead for use
with stylet 34 can have a distally-located recess that is
complementary to key 38.
[0034] In another example of the electrode assembly, referring to
the embodiment shown in FIGS. 3A and 3B, an electrode assembly 40
comprises an elongate lead 50 and a lead guide in the form of
cannula 46. In this embodiment, the lead guide is disposed about
the outer surface of the elongate lead, whereas in the embodiment
illustrated in FIG. 1A-1D, the elongate lead is disposed about the
outer surface of the lead guide. As with the embodiment described
above, elongate lead 50 has directional stimulation electrodes 52
positioned at a distal portion of elongate lead 50. As seen in FIG.
3B, directional electrodes 52 extend 120.degree. around the body of
elongate lead 50, but can extend to other degrees less than
360.degree. about the body of the lead. Elongate lead 50 also has
electrical contacts 24 for coupling to an external stimulator or
implantable pulse generator. Each of contacts 24 independently
supply electrical connectivity to electrodes 52. On its outer
surface, elongate lead 50 has a first rotation locking structure
that is a groove 56 which is contoured to receive a second rotation
locking structure that is a ridge 48 on the inside surface of
cannula 46.
[0035] In this embodiment, cannula 46 has an inner channel
configured to receive elongate lead 50. As stated above, on its
inside surface, cannula 46 comprises a ridge 48 which extends along
the length of cannula 46. Ridge 48 is contoured to mate with groove
56 of elongate lead 50 to form a locked relationship. A handle 45
can be fixed to the proximal end of cannula 46 to allow the user to
manually rotate cannula 46. Of course, cannula 46 could also be
rotated by other means, such as electrically or telemetrically.
[0036] In operation, the distal end of cannula 46 is inserted into
the patient's body. Elongate lead 50 is inserted into the inner
channel of cannula 46 such that groove 56 is aligned with ridge 48.
Because of the mating of ridge 48 and groove 56, elongate lead 50
is rotationally locked with cannula 46. Thus, as elongate lead 50
is being positioned at the target site, the user can turn handle 45
of cannula 46 to cause elongate lead 50 to rotate accordingly,
allowing the user to adjust the directional orientation of
directional electrodes 52. One or more of directional electrodes 52
can then be activated to provide electrical stimulation to the
target site.
[0037] In another example, referring to the embodiment shown in
FIG. 4, an electrode assembly 60 comprises an elongate lead 64 and
a lead guide in the form of a cannula 62. Cannula 62 has an inner
channel configured to receive elongate lead 64. A pair of first
rotational locking structures that are keys 66 are oppositely
positioned on the inside surface of cannula 62. Keys 66 are
contoured to mate with second locking structures, which are a pair
of oppositely positioned grooves 67 on elongate lead 64. Grooves 67
are contoured to mate with keys 66 to form a locked relationship.
Elongate lead 64 can have a pair of 120.degree. directional
stimulation electrodes 65 positioned on opposite sides of elongate
lead 64. Of course, other directional electrodes can also be used.
In operation, electrode assembly 60 is used in a manner similar to
that described for the above-mentioned embodiments.
[0038] In some embodiments, the electrode assembly further
comprises a lead guide holder for holding the lead guide. The lead
guide holder has a rotational indicator that indicates the
rotational orientation of the elongate lead and/or lead guide in
relation to a fixed point of reference (e.g., a stereotactic
headframe). For example, referring to the embodiment shown in FIG.
5, the electrode assembly of FIGS. 3A and 3B above may further
include a cannula holder 270 which is moveably attached to a
stereotactic headframe (not shown). As such, cannula holder 270 can
move in various axes, directions, or rotational planes on the
stereotactic headframe. Cannula holder 270 has an arm 272, which is
attached to the stereotactic headframe, and a ring 274 with a bore
276 through which cannula 46 is inserted. On ring 274 are a series
of evenly-spaced tics 278 positioned around the circumference of
bore 276. Tics 278 indicate the rotational orientation of cannula
46 with respect to an orientation indicator 28 that is aligned with
orientation indicator 27 on electrode lead 50. This orientation
information may be entered into a coordinate mapping system (such
as that described below) and used in combination with the fiducial
parameters provided by the stereotactic headframe for mapping of
the position and orientation of the elongate lead and/or electrode
in relation to structures in the brain. Other rotational indicators
could also be used for indicating the rotational orientation of the
elongate lead and/or lead guide in relation to a fixed point of
reference (e.g., a stereotactic headframe).
[0039] Of course other configurations of the first and second
rotation locking structures are contemplated. In other words, any
embodiments are contemplated where one of the components has a
portion that can be securely attached to another portion of the
other component to prevent rotational movement of one component
relative to the other. For example, the stylet can have an
irregularly shaped tip as the second rotation locking structure
that locks into a receptacle, which serves as the first rotation
locking structure, at the distal end of the elongate lead. The
first and/or second rotation locking structures need not extend the
entire length of the elongate lead.
[0040] FIGS. 6A-E show different non-circular cross-sectional
shapes for at least a portion of a stylet and a corresponding
receptacle of an elongate lead according to embodiments of the
present invention. The cross-sections in FIGS. 6A-E are taken along
a plane perpendicular to the longitudinal axis of the stylet. A
rectangle 170, an ellipse 172, a square 174, a triangle 176 and a
general triangular shape with a rounded surface 178 are shown in
FIGS. 6A-E, respectively. Other non-circular cross sections may
also be provided. These non-circular cross-sections, along with
their corresponding receptacles, may extend the length of the
stylet and/or elongate lead or may be provided at the proximal ends
and/or the distal ends of the stylet and the elongate lead or may
be provided at other locations such that a sufficiently uniform
force is transferred along the length of the stylet to the elongate
lead thereby causing the proximal ends and distal ends of the
stylet and the elongate lead to rotate together. Accordingly, the
ends of the stylet and the elongate lead do not become
misaligned.
[0041] In certain embodiments, the lead guide comprises one or more
gripping elements to provide the rotational fixation between the
elongate lead and the lead guide. The gripping element(s) is
designed to frictionally engage the elongate lead. In some
embodiments, the lead guide further comprises an activation
mechanism for causing the gripping elements to engage the elongate
lead, to release the elongate lead, and/or to lock the gripping
elements in their engaged or released positions. Any of various
activation mechanisms may be used for this particular function,
including mechanical (e.g., using a slide, pull, or button
actuation), pneumatic, or hydraulic mechanisms.
[0042] For example, referring to the embodiment shown in FIGS.
7A-7C, an electrode assembly 100 comprises an elongate lead 110 and
a lead guide as cannula 102. Elongate lead 110 has directional
stimulation electrodes 112 positioned at a distal portion of
elongate lead 110 and contacts 24 at a proximal portion of elongate
lead 110. Cannula 102 has an inner channel 106 configured to
receive elongate lead 110. At proximal and distal portions, cannula
102 has gripping elements 104 which are designed to frictionally
engage elongate lead 110, thereby restraining rotational movement
of elongate lead 110 relative to cannula 102. Referring to FIGS. 7B
and 7C, the pair of proximally located gripping elements 104 are
positioned on opposite sides of the inner surface of cannula 102.
Likewise, the pair of distally located gripping elements 104 are
also positioned on opposite sides of the inner surface of cannula
102. By an actuation mechanism (not shown), gripping elements 104
may alternately engage elongate lead 110 (see FIG. 7C) or release
elongate lead 110 (see FIG. 7B). A handle 105 can be fixed to the
proximal end of cannula 102 to allow the user to manually rotate
cannula 102. Of course, the cannula could be rotated by other means
as well.
[0043] In operation, the distal end of cannula 102 is inserted into
the patient's body. With gripping elements 104 in the released
position, elongate lead 110 is inserted into inner channel 106 of
cannula 102. After further advancement and positioning of elongate
lead 110 in the patient's body, the user can actuate gripping
elements 104 to engage and rotationally fix elongate lead 110.
Then, when the user turns handle 105 on cannula 102, elongate lead
110 will rotate accordingly, allowing the user to adjust the
directional orientation of directional electrodes 112. One or more
of directional electrodes 112 can then be activated to provide
electrical stimulation to the target site.
[0044] In certain embodiments, the lead guide is a delivery
structure that is designed to be positioned between the elongate
lead and a cannula. The delivery system may engage the elongate
lead using the mating mechanisms or gripping mechanisms described
above. For example, referring to the embodiment shown in FIG. 8, an
electrode assembly 70 comprises an elongate lead 80 and a lead
guide as delivery structure 90. Cannula 76 has an inner channel
configured to receive elongate lead 80 and delivery structure 90.
Elongate lead 80 has a directional stimulation electrode 82
extending around the body of elongate lead 80. Delivery structure
90 is positioned between elongate lead 80 and cannula 76. As such,
delivery structure 90 is configured to be insertable within the
inner channel of cannula 76. Delivery structure 90 also has an
inner channel which is configured to receive elongate lead 80. On
its inner surface, delivery structure 90 has gripping elements 92
which frictionally engage elongate lead 80.
[0045] In operation, the distal end of cannula 76 is inserted into
the patient's body. Then, delivery structure 90 (containing
elongate lead 80, which is frictionally engaged with delivery
structure 90 through gripping elements 92) is inserted into the
inner channel of cannula 76. Because delivery structure 90 is
rotationally locked with elongate lead 80, the user can turn
delivery structure 90 to cause elongate lead 80 to rotate in
concert accordingly, allowing the user to adjust the directional
orientation of directional electrode 82. Directional electrode 82
can then be activated to provide electrical stimulation to the
target site.
[0046] In an alternate embodiment, delivery structure 90 may have
additional gripping elements which frictionally engage cannula 76.
In this case, cannula 76 is rotationally locked with delivery
structure 90, which in turn, is rotationally locked with elongate
lead 80. As such, the user can turn cannula 76 to cause elongate
lead 80 to rotate in concert, allowing the user to adjust the
directional orientation of directional electrode 82.
[0047] The gripping element(s) may have any of various shapes,
sizes, configurations, textures, and material compositions suitable
for performing the above-described function. For example, the
gripping element(s) may be formed of a deformable material, such as
a soft thermoplastic material (e.g., silicone or polyurethane) and
shaped to conform to the contours of the elongate lead.
Alternatively, the gripping elements could comprise a more rigid
base that is padded with a softer material such as silicone or
polyurethane to prevent damage to the lead.
[0048] The gripping element(s) may be located at any of various
positions on the lead guide, including the outer surface, proximal
portions, or distal portions of the lead guide. The gripping
element(s) and the lead guide may form a single unitary structure,
or the two components may be separate units that are coupled
together. Further, when more than one gripping element is employed,
the gripping elements can be placed in different positions relative
to each other so long as they collectively perform their intended
function. For example, two or more gripping elements may be
arranged in opposition to each other such that they engage opposite
sides of the elongate lead, or the gripping element(s) may
circumferentially surround the elongate lead.
[0049] This first aspect of the present invention may be combined
with any of the features in the second and/or third aspects of the
present invention.
[0050] In a second aspect, the present invention provides an
elongate lead having one or more radiologically-visible features
that indicate the rotational orientation of the directional
electrode under radiologic imaging. The radiologically-visible
feature may be radiolucent, radiopaque, or otherwise, so long as
the feature is visible under radiologic imaging. The radiologic
imaging may be any of various imaging modalities that are used to
view an object inserted into a patient's body, including x-ray,
x-ray fluoroscopy, CT scan, or MRI.
[0051] In certain embodiments, the radiologically-visible feature
has a shape that is asymmetric with respect to the central
longitudinal axis of the elongate lead. By having a shape that is
asymmetric with respect to the central longitudinal axis of the
elongate lead, the image of the feature under radiologic imaging
will vary with the rotation of the elongate lead with respect to
the particular view. For example, when viewed directly face-on, the
feature will have one image; and when the elongate lead is rotated
180.degree., the see-through view of the feature will have a
different (flipped) image. This allows the user to determine and/or
adjust the rotational orientation of the directional electrode
under radiologic imaging.
[0052] For example, referring to the embodiment shown in FIGS. 9A
and 9B, an elongate lead 120, with a central longitudinal axis 124,
has a radiopaque feature in the form of marking 126 which is
asymmetric with respect to central longitudinal axis 124. Elongate
lead 120 has a directional stimulation electrode 122 that extends
120.degree. around the body of elongate lead 120 and an electrical
contact 128 to supply electrical connectivity to electrode 122. In
FIG. 9A, elongate lead 120 is rotated such that directional
electrode 120 is facing out of the page (i.e., direct face-on
view), and in FIG. 9B, elongate lead 120 is rotated 180.degree.
such that directional electrode 122 is facing into the page (i.e.,
see-through view). As such, the image of marking 126 seen in FIG.
9A is different from the flipped image 126' of marking 126 see in
FIG. 9B. In operation, elongate lead 120 is positioned in the body
and viewed under x-ray fluoroscopy. Since marking 126 is aligned
with directional electrode 122, by visualizing marking 126 at
various viewpoints under x-ray flouroscopy, the user is able to
determine the orientation of directional electrode 122 and make any
necessary adjustments. Directional electrode 122 is then activated
to provide electrical stimulation to the target site.
[0053] In another example, referring to the embodiment shown in
FIGS. 10A and 10B, an elongate lead 130 has a central longitudinal
axis 134, a marking 136 which is asymmetric with respect to central
longitudinal axis 134, a directional electrode 122, and an
electrical contact 128 to supply electrical connectivity to
electrode 122. FIG. 10A shows a direct face-on view of marking 136,
and FIG. 10B shows a see-through image 136' of marking 136 when
elongate lead 130 is rotated 180.degree.. In another example,
referring to the embodiment shown in FIGS. 11A and 11B, an elongate
lead 140 has a central longitudinal axis 144 and a marking 146
which is asymmetric with respect to central longitudinal axis 144.
FIG. 11A shows a direct face-on view of marking 146, and FIG. 11B
shows a see-through image 146' of marking 146 when elongate lead
140 is rotated 180.degree.. Of course, the above described
asymmetric features are only exemplary and other asymmetric
features could also be used. For example a "C" shaped feature could
also be used.
[0054] In a comparative example, referring to FIGS. 12A and 12B, a
marking 156 is symmetric with respect to the central longitudinal
axis 154 of elongate lead 150. The direct face-on view of marking
156 in FIG. 12A is identical to the see-through image 156' of
marking 156 when elongate lead 150 is rotated 180.degree..
[0055] In certain embodiments, the radiologically-visible
feature(s) provides an image that becomes distorted when a proximal
portion of the elongate lead is rotationally misaligned with a
distal portion of the elongate lead (i.e., the elongate lead is
twisted). By viewing the radiologic image of the
radiologically-visible feature, the user can determine if there is
any misalignment between proximal and distal portions of the
elongate lead. For example, referring to the embodiment shown in
FIGS. 13A and 13B, an elongate lead 160 has a directional
stimulation electrode 164 at its distal portion and an electrical
contact 24 to provide electrical connectivity to directional
electrode 164. Elongate lead 160 also has an orientation indicator
166 which is aligned with the orientation of directional electrode
164. Elongate lead 160 also has a radiopaque feature in the form of
a radiopaque stripe mark 162 on the surface of elongate lead
160.
[0056] In operation, elongate lead 160 is inserted into the body
and rotated at its proximal end to place electrode 164 in the
desired orientation based on the alignment of orientation indicator
166. However, if rotational movement at the proximal end of
elongate lead 160 is not fully translated to corresponding
rotational movement at the distal end, the resulting twisting in
elongate lead 160 will cause orientation indicator 166 to be
misaligned with directional electrode 164. When viewed under x-ray
fluoroscopy, as shown in FIG. 13B, it will be apparent that
twisting in elongate lead 160 has caused stripe mark 162 to form a
distorted image 162'. On this basis, the user will be aware of the
twisting in elongate lead 160 and take appropriate action.
Directional electrode 164 is then activated to provide electrical
stimulation to the target site.
[0057] In some cases, the radiologically-visible feature is
radiolucent. For example, referring to the embodiment shown in
FIGS. 14A and 14B, an elongate lead 170 has a directional
simulation electrode 174 at its distal portion and an electrical
contact 24 to provide electrical connectivity to directional
electrode 174. Elongate lead 170 also has two radiolucent cut-out
windows, 172 and 173, that are adjacently positioned on opposite
sides of elongate lead 170. FIG. 14A shows elongate lead 170 in one
rotational orientation and FIG. 14B shows elongate lead 170 rotated
180.degree. from the view shown in FIG. 14A. Based on the positions
of radiolucent cut-out windows 172 and 173 under radiologic
imaging, a user can determine the orientation of elongate lead 170
and/or directional electrode 174.
[0058] The radiologically-visible feature(s) may also be positioned
anywhere along the length of the elongate lead, including proximal
and distal portions. In some cases, the elongate lead may have two
or more radiologically-visible features which are positioned in
such a manner (e.g., alternating or staggered configurations) for
more accurate determinations of orientation.
[0059] The material used to form the radiopaque feature(s) may be
any of various radiopaque materials, such as metallic materials or
semi-metallic materials. Non-limiting examples of materials include
titanium dioxide, bismuth compounds, or barium sulfate. The
radiopaque feature(s) can be affixed to the elongate lead in any of
various ways, including applying as a surface marking, embedding
within the wall of the elongate lead, or inserting within the
elongate lead.
[0060] This second aspect of the present invention may be combined
with any of the features in the first and/or third aspects of the
present invention.
[0061] In any of the embodiments described above, the size, shape,
configuration, and dimensions of the elongate lead will vary
depending upon the particular application. For example, the shape
of the elongate lead may be cylindrical, flat, conical, etc. Where
the elongate lead is cylindrical, the diameter of the elongate lead
may be in the range of about 0.5 to 1.50 mm, but other diameters
are also possible, depending upon the particular application. The
length of the elongate lead may be in the range of about 10 to 60
cm, but other lengths are also possible, depending upon the
particular application. In some cases, the size, shape,
configuration, and dimensions of the elongate lead are selected for
use in electrical stimulation of brain structures. For example,
co-pending application Ser. No. 10/602,319 (filed Jun. 24, 2003)
describes various stimulation leads and electrodes which are
suitable for use in the present invention. The material composition
and mechanical properties (i.e. the flexibility) of the body of the
elongate lead will vary depending upon the particular application.
In some cases, the body of the elongate body is formed of a
non-conductive material, such as a polymeric material, glass or
quartz including silicone and/or polyurethane.
[0062] In any of the embodiments described above, the elongate lead
has at least one stimulation electrode positioned at a distal
portion of the elongate lead. The stimulation electrode is designed
to provide electrical stimulation to a part of a patient's body
(e.g., parts of the brain). As mentioned above, the stimulation
electrodes are directional electrodes that extend less than
360.degree. about the body of the elongate lead. This means that
the stimulation electrode bands do not form a continuous electrode
surface, but rather the electrode bands are segmented into a
plurality of individual electrodes that are substantially isolated
from each other. Individual electrodes can range in an angular
distance around the exterior of the body of the elongate lead by as
little as a few degrees to almost completely around the body of the
lead. The radial span of the electrodes can be, for example,
120.degree. about the body of the elongate lead. Of course, the
elongate lead can also include, in addition to one or more
directional electrodes, cylindrical electrodes that extend
360.degree. about the body of the lead. Where the elongate lead has
multiple electrodes, the electrodes may be electrically isolated
from each other and electively activated. This selective
powerability of the electrodes provides a desired, focused (i.e.
directed) electrical field around the body of the lead. The
material composition, electrical properties (e.g., impedance),
dimensions (e.g., height, width, axial spacing, and shape), and
number (e.g., single or multiple) of the stimulation electrodes on
the elongate lead will vary depending upon the particular
application. For example, the electrodes may have a cylindrical
shape, an oval shape, or a rectangular shape. In fact, the
individual electrodes may take any variety of shapes to produce the
desired focused and/or directional electric field.
[0063] In any of the embodiments described above, the lead guide
and the delivery structure may have any of various shapes, sizes,
dimensions, mechanical properties (e.g., stiffness), and material
compositions, depending upon the particular application. For
example, the lead guide and/or the delivery structure may be made
of tungsten, stainless steel, MP35N, and may be coated with PTFE,
parylene, or ETFE. The lead guide should be rigid enough such that
the distal end of the lead guide moves in unison with the proximal
end when the lead guide is rotated. Similarly, the delivery
structure should be rigid enough such that the distal end of the
delivery structure moves in unison with the proximal end when the
delivery structure is rotated.
[0064] In a third aspect, the present invention provides an
electrode system for determining the position and/or rotational
orientation of an electrode positioned within a body. The system
comprises an elongate lead having at least one directional
electrode positioned at a distal portion of the elongate lead and a
position determining apparatus for determining the position and/or
orientation of the electrode when the electrode is positioned in a
body.
[0065] Any of various types of apparatuses for determining the
position of a remote object can be used in the electrode system.
The position and/or orientation may be determined within a
one-dimensional, two-dimensional, or three-dimensional framework.
In certain embodiments, the system uses remote signal detection for
determining the position and/or orientation of an electrode. The
remote signal may emitted from the electrode itself, or may be
emitted from the body tissue being stimulated by the electrode (for
example, brain waves that can be captured by EEG). As such, the
position determining apparatus comprises a plurality of signal
detection sensors, positioned externally (for example, on the
scalp) or internally to the patient's body (for example,
subcutaneously or on the cortex), for detecting the desired signal.
The number and spatial positions of the signal detection probes
will depend upon various conditions, such as the location of the
target site, the strength of the signal, the desired resolution,
and the desired number of positional axes (1-D, 2-D, or 3-D).
[0066] In some cases, the system comprises three or more signal
detection probes to allow for triangulation of the electrode. For
example, by triangulation based on the differential strengths of
the detected signals from three signal detection probes (which will
vary according to the distance of the signal detection probes from
the signal), the x, y, z coordinates and the orientation of the
electrode can be calculated. Any of various types of signal
processing systems and computer systems can be used to process the
signal and perform the mathematical calculations for determining
the position and/or orientation of the electrode.
[0067] For example, referring to the embodiment shown in FIG. 15,
an electrode system 200 comprises three EEG sensors 202 located on
pre-determined spatial positions on the top of a patient's head
190. Each of EEG sensors 202 are electrically coupled via wires 204
to separate input channels of a conventional multiplexer 210, which
samples each sensor input channel in a time-multiplexed fashion.
The selected EEG sensor signal is then input into an amplifier 214
and the amplified signal is sent to a signal processor 216 to
process the signal. Signal processor 216 contains an
analog-to-digital converter (A/D) 218 to convert the signals into
digital form, which is then transmitted to a conventional computer
220 or clinician and/or patient programmer containing a
microprocessor 226 and memory 222. Alternatively, a conventional
EEG apparatus may be used in combination with the electrode system,
with the EEG data being stored and then transferred to the
electrode system.
[0068] Memory 222 is loaded with software 224 which is configured
to establish an orthogonal three-dimensional coordinate system and
receive spatial information about the relevant anatomic structures
and/or other fiducial references, which is then stored in memory
222. Software 224 also receives and stores information about the
spatial positioning of EEG sensors 202. Using any of various
triangulation algorithms, software 224 then uses the signal data to
calculate the position and/or orientation of the electrode inside
the brain. A mapping function is then used to translate the
calculated position and/or orientation into the reference frame of
the stored coordinate system containing the fixed anatomic
structures and/or other fiducial references (e.g., the AC-PC plane
of the brain, or the neurosurgical stereotactic headframe). A
three-dimensional composite image, showing a lead 240 and
electrodes 242, is then displayed on a display screen 230. This
three-dimensional image can be manipulated to provide various
views, including coronal, sagittal, and axial views. In some cases,
the volume of activation provided by electrodes 242 may also be
displayed in conjunction with the relevant brain structures. This
allows the user to adjust the orientation and/or position of lead
240, or adjust various stimulation parameters such as signal
intensity or amplitude, to specifically target the relevant brain
structures.
[0069] The flowchart in FIG. 16 illustrates the above-mentioned
processes performed by software 224. Namely, software 224
establishes an orthogonal 3-D coordinate system (process blocks 250
and 262); receives spatial information about the fiducial
references (process block 252); stores the fiducial references
within the coordinate system (process blocks 254 and 264); receives
signal data from the EEG sensors (process block 256); calculates
the position and/or orientation of the signal (process block 258);
and, maps and displays the signal within the stored coordinate
system (process blocks 260 and 262).
[0070] In certain embodiments, the position determining apparatus
uses any of various electromechanical position transducers for
determining the position of the electrode based on the movement of
the elongate lead and/or lead guide. For example, the linear motion
actuation systems and/or navigation systems described in co-pending
application Ser. No. 10/602,319 (filed Jun. 24, 2003) may be used
in the position determining apparatus. Any of various types of
signal processing systems and computer systems, including those
mentioned above, can be used to process the signal and perform the
mathematical calculations for determining the position and/or
orientation of the electrode.
[0071] In certain embodiments, the position determining apparatus
comprises a sensing electrode positioned on the elongate lead. The
sensing electrode has an impedance suitable for detecting and/or
recording an electrical signal from neural structures in the brain.
Based on the characteristics of signals emitted by different neural
structures, and by comparing with the electrical signals detected
by the sensing electrodes, the position and/or orientation of the
elongate lead may be determined. Any of various types of signal
processing systems and computer systems, including those mentioned
above, can be used to process the signal and perform the
mathematical calculations for determining the position and/or
orientation of the electrode.
[0072] In certain embodiments, the position determining apparatus
comprises a computer system with a user interface for receiving
manually inputted data which can be used to calculate the position
and/or orientation of the electrode. For example, the position
determining apparatus may receive manually inputted data for the
location of the tip of the elongate lead (for example, as indicated
by the stereotactic headframe), the rotational orientation of the
elongate lead (for example, using the cannula holder shown in FIG.
5), and the angle of entry of the elongate lead (for example, as
indicated by the stereotactic headframe via arc and ring
coordinates). The system can then use this data to map the position
and/or orientation into a coordinate system containing the fixed
anatomic structures and/or other fiducial references (e.g., the
AC-PC plane of the brain, or the neurosurgical stereotactic
headframe).
[0073] This third aspect of the present invention may be combined
with any of the features in the first and/or second aspects of the
present invention.
[0074] The present invention may have any of various applications
in electrical stimulation treatments. For example, in addition to
brain stimulation, the present invention may be used for delivering
electrical stimulation to the spinal cord, spinal nerve roots,
ganglions, and other structures of the nervous system.
[0075] The foregoing description and examples have been set forth
merely to illustrate the invention and are not intended as being
limiting. Each of the disclosed aspects and embodiments of the
present invention may be considered individually or in combination
with other aspects, embodiments, and variations of the invention.
Further, while certain features of embodiments of the present
invention may be shown in only certain figures, such features can
be incorporated into other embodiments shown in other figures while
remaining within the scope of the present invention. In addition,
unless otherwise specified, none of the steps of the methods of the
present invention are confined to any particular order of
performance. Modifications of the disclosed embodiments
incorporating the spirit and substance of the invention may occur
to persons skilled in the art and such modifications are within the
scope of the present invention. Furthermore, all references cited
herein are incorporated by reference in their entirety.
* * * * *