U.S. patent application number 13/101009 was filed with the patent office on 2011-11-24 for systems and methods for tissue ablation.
This patent application is currently assigned to NIMBUS CONCEPTS, LLC. Invention is credited to Scott A. Brandt, Robert E. Wright.
Application Number | 20110288540 13/101009 |
Document ID | / |
Family ID | 44973084 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288540 |
Kind Code |
A1 |
Wright; Robert E. ; et
al. |
November 24, 2011 |
SYSTEMS AND METHODS FOR TISSUE ABLATION
Abstract
Systems and methods for tissue ablation. Systems include needles
with deployable filaments capable of producing asymmetrical offset
lesions at target volumes, which may include a target nerve.
Ablation of at least a portion of the target nerve may inhibit the
ability of the nerve to transmit signals, such as pain signals, to
the central nervous system. The offset lesion may facilitate
procedures by directing energy towards the target nerve and away
from collateral structures. Example anatomical structures include
lumbar, thoracic, and cervical medial branch nerves and rami and
the sacroiliac joint.
Inventors: |
Wright; Robert E.; (Denver,
CO) ; Brandt; Scott A.; (Denver, CO) |
Assignee: |
NIMBUS CONCEPTS, LLC
Denver
CO
|
Family ID: |
44973084 |
Appl. No.: |
13/101009 |
Filed: |
May 4, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61347351 |
May 21, 2010 |
|
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|
61357886 |
Jun 23, 2010 |
|
|
|
61357894 |
Jun 23, 2010 |
|
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Current U.S.
Class: |
606/33 |
Current CPC
Class: |
A61B 2018/1475 20130101;
A61B 2018/143 20130101; A61B 2018/1427 20130101; A61B 18/1206
20130101; A61B 2018/1253 20130101; A61B 2018/00577 20130101; A61B
2018/0044 20130101; A61B 18/1477 20130101 |
Class at
Publication: |
606/33 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1. A needle comprising: an elongate member having a distal end; a
tip coupled to the distal end of the elongate member, the tip
comprising a bevel portion comprising a point on a side of the
elongate member; and a plurality of filaments movable between a
first position at least partially in the elongate member and a
second position at least partially out and to the side of the
elongate member, the plurality of filaments and the tip configured
to transmit radio frequency energy from a probe to operate as a
monopolar electrode.
2. The needle of claim 1, wherein the elongate member has a
proximal end and wherein the needle further comprises a filament
deployment mechanism coupled to the proximal end of the elongate
member, the filament deployment mechanism comprising: an advancing
hub including a stem coupled to the plurality of filaments; a spin
collar including a helical track, the stem of the advancing hub at
least partially inside the spin collar; and a main hub comprising a
stem comprising a helical thread configured to cooperate with the
helical track, the stem of the main hub at least partially inside
the spin collar, the stem of the advancing hub at least partially
inside the main hub, wherein, upon rotation of the spin collar, the
filaments are configured to move between the first position and the
second position.
3. The needle of claim 2, wherein a single wire comprises the
plurality of filaments and wherein a proximal end of the wire is
coupled to the stem of the advancing hub.
4. The needle of claim 2, wherein at least one of the helical track
and the helical thread includes a plurality of detents configured
to indicate partial deployment or retraction of the plurality of
filaments.
5. The needle of claim 4, wherein the first position is a fully
retracted position and the second position is a fully deployed
position, and wherein the detents are configured to provide an
audible or tactile feedback to a user when the filaments are at a
third position between the first position and the second position,
a fourth position between the third position and the second
position, and a fifth position between the fourth position and the
second position.
6. The needle of claim 5, wherein the plurality of filaments are
proximal to the point in the third position, the plurality of
filaments are substantially longitudinally aligned with the point
in the fourth position, and the plurality of filaments are distal
to the point in the fifth position.
7. The needle of claim 1, wherein the bevel portion has a bevel
angle between about 20.degree. and about 30.degree..
8. The needle of claim 1, wherein each of the plurality of
filaments has a distal end including a bevel facing away from the
tip.
9. The needle of claim 8, wherein the bevels of the plurality of
filaments are at an angle between about 25.degree. and about
35.degree..
10. The needle of claim 1, wherein a single wire comprises the
plurality of filaments.
11. The needle of claim 1, further comprising an insulating coating
at least partially covering the point.
12. The needle of claim 1, wherein the tip comprises a stem at
least partially in the elongate member, the stem including a first
filament lumen and a second filament lumen.
13. The needle of claim 12, wherein stem includes a third lumen and
wherein the bevel portion comprises a fluid port in communication
with the third lumen.
14. The needle of claim 1, wherein the elongate member has a
proximal end, and wherein the needle further comprises a rotational
deployment mechanism coupled to the proximal end of the elongate
member, the deployment mechanism comprising indicia of fractional
deployment of the plurality of filaments relative to the tip.
15. The needle of claim 15, wherein the indicia include at least
one of audible and tactile detents.
16. A needle comprising: an elongate member having a distal end; a
tip comprising a first body portion including a tapered portion and
a point, the tapered portion including a plurality of filament
ports; and a second body portion coupled to the distal end of the
elongate member, the second body portion at an angle with respect
to the first body portion; and a plurality of filaments movable
between a first position at least partially in at least one of the
tip and the elongate member and a second position at least
partially out of the filament ports, the plurality of filaments and
the tip configured to transmit radio frequency energy from a probe
to operate as a monopolar electrode.
17. The needle of claim 16, wherein the angle is between about
20.degree. and about 30.degree..
18. The needle of claim 16, wherein each of the plurality of
filaments has a distal end including a pencil-point tip.
19. The needle of claim 16, wherein the tapered portion includes a
pencil-point tip.
20. A method of heating a vertebral disc, the method comprising:
positioning a distal end of a needle in a posterior annulus;
deploying a filament out of the needle; traversing the posterior
annulus from lateral to medial; applying radio frequency energy to
the tip and to the filament; and ablating pain fibers in the
posterior annulus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application No. 61/347,351,
filed May 21, 2010, U.S. Provisional Patent Application No.
61/357,886, filed Jun. 23, 2010, and U.S. Provisional Patent
Application No. 61/357,894, filed Jun. 23, 2010, each of which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] 1. Field
[0003] The present application generally relates to thermal
ablation systems and methods, and more particularly to systems and
methods for radio frequency (RF) neurotomy, such as spinal RF
neurotomy.
[0004] 2. Description of the Related Art
[0005] Thermal ablation involves the creation of temperature
changes sufficient to produce necrosis in a specific volume of
tissue within a patient. The target volume may be, for example, a
nerve or a tumor. A significant challenge in ablation therapy is to
provide adequate treatment to the targeted tissue while sparing the
surrounding structures from injury.
[0006] RF ablation uses electrical energy transmitted into a target
volume through an electrode to generate heat in the area of the
electrode tip. The radio waves emanate from a non-insulated distal
portion of the electrode tip. The introduced radiofrequency energy
causes molecular strain, or ionic agitation, in the area
surrounding the electrode as the current flows from the electrode
tip to ground. The resulting strain causes the temperature in the
area surrounding the electrode tip to rise. RF neurotomy uses RF
energy to cauterize a target nerve to disrupt the ability of the
nerve to transmit pain signals to the brain.
SUMMARY
[0007] This application describes example embodiments of devices
and methods for tissue ablation, such as spinal radio frequency
neurotomy. Systems include needles with deployable filaments
capable of producing asymmetrical offset lesions at target volumes,
which may include a target nerve. Ablation of at least a portion of
the target nerve may inhibit the ability of the nerve to transmit
signals, such as pain signals, to the central nervous system. The
offset lesion may facilitate procedures by directing energy towards
the target nerve and away from collateral structures. Example
anatomical structures include lumbar, thoracic, and cervical medial
branch nerves and rami and the sacroiliac joint.
[0008] In some embodiments, a needle comprises an elongate member
having a distal end, a tip coupled to the distal end of the
elongate member, and a plurality of filaments. The tip comprises a
bevel to a point. The plurality of filaments is movable between a
first position at least partially in the elongate member and a
second position at least partially out of the elongate member. The
plurality of filaments and the tip are configured to transmit radio
frequency energy from a probe to operate as a monopolar
electrode.
[0009] In some embodiments, a needle comprises an elongate member
having a distal end, a tip coupled to the distal end of the
elongate member, and a plurality of filaments. The tip comprises a
bevel portion comprising a point on a side of the elongate member.
The plurality of filaments is movable between a first position at
least partially in the elongate member and a second position at
least partially out of and proximate to the side of the elongate
member. The plurality of filaments and the tip are configured to
transmit radio frequency energy from a probe to operate as a
monopolar electrode.
[0010] In some embodiments, a needle comprises an elongate member
having a proximal end and a distal end, a tip coupled to the distal
end of the elongate member, a plurality of filaments, and a
filament deployment mechanism coupled to the proximal end of the
elongate member. The tip comprises a bevel portion comprising a
point. The plurality of filaments is movable between a first
position at least partially in the elongate member and a second
position at least partially out of the elongate member. The
plurality of filaments and the tip are configured to transmit radio
frequency energy from a probe to operate as a monopolar electrode.
The filament deployment mechanism comprises an advancing hub, a
spin collar, and a main hub. The advancing hub includes a stem
coupled to the plurality of filaments. The spin collar includes a
helical track. The stem of the advancing hub is at least partially
inside the spin collar. The main hub comprises a stem comprising a
helical thread configured to cooperate with the helical track. The
stem of the main hub is at least partially inside the spin collar.
The stem of the advancing hub is at least partially inside the main
hub. Upon rotation of the spin collar, the filaments are configured
to move between the first position and the second position.
[0011] In some embodiments, a needle comprises an elongate member
having a distal end, a tip coupled to the distal end of the
elongate member, and a plurality of filaments. The tip comprises a
point. The plurality of filaments is movable between a first
position at least partially in the elongate member and a second
position at least partially out of the elongate member. The
plurality of filaments and the tip are configured to transmit radio
frequency energy from a probe to operate as a monopolar electrode.
A single wire comprises the plurality of filaments.
[0012] In some embodiments, a needle comprises an elongate member
having a distal end, a tip coupled to the distal end of the
elongate member, and a plurality of filaments. The tip comprises a
bevel to a point. The plurality of filaments is movable between a
first position at least partially in the elongate member and a
second position at least partially out of the elongate member. The
plurality of filaments and the tip are configured to transmit radio
frequency energy from a probe to operate as a monopolar electrode.
The tip comprises a stem at least partially in the elongate member.
The stem includes a first filament lumen, a second filament lumen,
and a third lumen. The bevel portion comprises a fluid port in
fluid communication with the third lumen.
[0013] In some embodiments, a needle comprises an elongate member
having a proximal end and a distal end, a tip coupled to the distal
end of the elongate member, a plurality of filaments, and a
rotational deployment mechanism coupled to the proximal end of the
elongate member. The tip comprises a bevel to a point. The
plurality of filaments is movable between a plurality of positions
between at least partially in the elongate member and at least
partially out of the elongate member. The deployment mechanism
comprises indicia of fractional deployment of the plurality of
filaments relative to the tip. The plurality of filaments and the
tip are configured to transmit radio frequency energy from a probe
to operate as a monopolar electrode.
[0014] In some embodiments, a needle comprises an elongate member
having a distal end, a tip, and a plurality of filaments. The tip
comprises a first body portion and a second body portion. The first
body portion includes a tapered portion and a point. The tapered
portion includes a plurality of filament ports. The second body
portion is coupled to the distal end of the tip. The second body
portion is at an angle with respect to the first body portion. The
plurality of filaments is movable between a first position at least
partially in at least one of the tip and the elongate member and a
second position at least partially out of the filament ports. The
plurality of filaments and the tip are configured to transmit radio
frequency energy from a probe to operate as a monopolar
electrode.
[0015] In some embodiments, a method of heating a vertebral disc
comprises: positioning a distal end of a needle in a posterior
annulus; deploying a filament out of the needle; traversing the
posterior annulus from lateral to medial; applying radio frequency
energy to the tip and to the filament; and ablating pain fibers in
the posterior annulus.
[0016] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member, an actuator interconnected to the plurality
of filaments, and a lumen in the elongate member. The tip is shaped
to pierce tissue of the patient. Movement of the actuator relative
to the hub moves the plurality of filaments relative to the tip.
The lumen and the tip are configured to accept an RF probe such
that an electrode of an inserted RF probe, the tip, and the first
and second filaments are operable to form a single monopolar RF
electrode.
[0017] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The actuator is
operable to move the plurality of filaments relative to the hub,
the elongate member, and the tip between the retracted position and
a fully deployed position. In the fully deployed position, the
plurality of filaments extends outwardly and away from the tip.
Each filament comprises a distal end that defines a point in the
fully deployed position. Each point is distal to the distal end of
the needle. The average of all the points is offset from a central
longitudinal axis of the elongate member.
[0018] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The actuator is
operable to move the plurality of filaments relative to the hub,
the elongate member, and the tip between the retracted position and
a deployed position. In the deployed position, the plurality of
filaments extends outwardly and away from the tip. Each filament
comprises a distal end that defines a point in the deployed
position. Each point is distal to the distal end of the needle.
Each point is on a common side of a plane that contains a central
longitudinal axis of the elongate member.
[0019] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The plurality of
filaments consists of a first filament and a second filament, and
the needle contains no filaments other than the first and second
filaments. The actuator is operable to move the plurality of
filaments relative to the hub, the elongate member, and the tip
between the retracted position and a deployed position. In the
deployed position, the plurality of filaments extends outwardly and
away from the tip. Each filament comprises a distal end that
defines a point in the deployed position. Each point is distal to
the distal end of the needle. In the deployed position, a midpoint
between the distal end of the first filament and the distal end of
the second filament is offset from a central longitudinal axis of
the needle.
[0020] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The plurality of
filaments consists of a first filament and a second filament, and
the needle contains no filaments other than the first and second
filaments. The actuator is operable to move the plurality of
filaments relative to the hub, the elongate member, and the tip
between the retracted position and a deployed position. In the
deployed position, the plurality of filaments extends outwardly and
away from the tip. Each filament comprises a distal end that
defines a point in the deployed position. Each point is distal to
the distal end of the needle. In their respective deployed
positions, each distal end defines a vertex of a polygon. A
centroid of the polygon is offset from a central longitudinal axis
of the needle.
[0021] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The plurality of
filaments consists of a first filament and a second filament, and
the needle contains no filaments other than the first and second
filaments. The actuator is operable to move the plurality of
filaments relative to the hub, the elongate member, and the tip
between the retracted position and a deployed position. In the
deployed position, the plurality of filaments extends outwardly and
away from the tip. Each filament comprises a distal end that
defines a point in the deployed position. Each point is distal to
the distal end of the needle. In their respective deployed
positions, each of the plurality of filaments points in an at least
partially distal direction.
[0022] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The plurality of
filaments consists of a first filament and a second filament, and
the needle contains no filaments other than the first and second
filaments. The actuator is operable to move the plurality of
filaments relative to the hub, the elongate member, and the tip
between the retracted position and a deployed position. In the
deployed position, the plurality of filaments extends outwardly and
away from the tip. Each filament comprises a distal end that
defines a point in the deployed position. Each point is distal to
the distal end of the needle. When the plurality of filaments are
in the deployed position, portions of each filament extend
outwardly away from the tip. Each portion of each filament
extending outwardly away from the tip is straight.
[0023] In some embodiments, a needle for insertion into a patient
during an RF ablation procedure comprises a hub, an elongate member
fixed to the hub, a tip fixed to the elongate member at a distal
end of the needle, a plurality of filaments in at least a portion
of the elongate member in a retracted position, and an actuator
interconnected to the plurality of filaments. The plurality of
filaments consists of a first filament and a second filament, and
the needle contains no filaments other than the first and second
filaments. The actuator is operable to move the plurality of
filaments relative to the hub, the elongate member, and the tip
between the retracted position and a deployed position. In the
deployed position, the plurality of filaments extends outwardly and
away from the tip. Each filament comprises a distal end that
defines a point in the deployed position. Each point is distal to
the distal end of the needle. When the plurality of filaments is in
the deployed position, the tip comprises an angle of at least
200.degree. about the central longitudinal axis of the elongate
member that is free of filaments.
[0024] In some embodiments, a method of performing spinal RF
neurotomy in a patient comprises moving a tip of a needle to a
first position proximate to a target nerve along the spine of the
patient, after achieving the first position, advancing a plurality
of filaments relative to the tip to a deployed position, and after
the advancing step, applying RF energy to the tip and plurality of
filaments, wherein said applying generates heat that ablates a
portion of the target nerve.
[0025] In some embodiments, a method of performing lumbar RF
neurotomy on a medial branch nerve in a patient comprises: moving a
tip of a needle to a first position between the transverse and
superior articular processes of a lumbar vertebra such that an end
point of the tip is proximate to a surface of the vertebra; after
achieving the first position, advancing a plurality of filaments
relative to the tip to a deployed position; and after advancing the
plurality of filaments, applying RF energy to the tip and the
plurality of filaments. Said applying generates heat that ablates a
portion of the medial branch nerve.
[0026] In some embodiments, a method of performing sacroiliac joint
RF neurotomy in a patient comprises: a. moving a tip of a needle to
a first position proximate to a sacrum of the patient; b. advancing
a plurality of filaments relative to the tip to a first deployed
position; c. applying RF energy to the tip and plurality of
filaments, wherein the applying generates heat that ablates a first
volume; d. retracting the plurality of filaments; e. with the tip
in the first position, rotating the needle about a central
longitudinal axis of the needle to re-orient the plurality of
filaments; f re-advancing the plurality of filaments relative to
the tip; and g. re-applying RF energy to the tip and plurality of
filaments, wherein the re-applying comprises ablating a second
volume proximate to the tip, wherein a center of the first volume
is offset from a center of the second volume.
[0027] In some embodiments, a method of performing thoracic RF
neurotomy on a medial branch nerve in a patient comprises: moving a
tip of a needle to a first position proximate a superior surface of
a transverse process of a thoracic vertebra such that an end point
of the tip is proximate to the superior surface; after achieving
the first position, advancing a plurality of filaments relative to
the tip toward a vertebra immediately superior to the thoracic
vertebra to a deployed position; and after advancing the plurality
of filaments, applying RF energy to the tip and the plurality of
filaments, wherein said applying generates heat that ablates a
portion of the medial branch nerve between the thoracic vertebra
and the vertebra immediately superior to the thoracic vertebra.
[0028] In some embodiments, a method of performing cervical medial
branch RF neurotomy on a third occipital nerve of a patient
comprises: a. positioning the patient in a prone position; b.
targeting a side of the C2/3 Z-joint; c. rotating the head of the
patient away from the targeted side; d. locating the lateral aspect
of the C2/3 Z-joint; e. moving, after steps a, b, c and d, a tip of
a needle over the most lateral aspect of bone of the articular
pillar at the juncture of the C2/3 z-joint to a first position
contacting bone proximate to the most posterior and lateral aspect
of the z-joint complex; f retracting, after step e, the tip of the
needle a predetermined distance from the first position; g.
extending, after step f, a plurality of filaments outwardly from
the tip and towards the lateral aspect of the C2/3 z-joint such
that the plurality of filaments are positioned straddling the
lateral joint lucency and posterior to the C2/3 neural foramen; h.
verifying, after step g, the position of the tip and filaments by
imaging the tip and a surrounding volume; and i. applying, after
step h, RF energy to the tip and the plurality of filaments,
wherein the applying generates heat that ablates a portion of the
third occipital nerve.
[0029] For purposes of summarizing the invention and the advantages
achieved over the prior art, certain objects and advantages of the
invention are described herein. Of course, it is to be understood
that not necessarily all such objects or advantages need to be
achieved in accordance with any particular embodiment. Thus, for
example, those skilled in the art will recognize that the invention
may be embodied or carried out in a manner that achieves or
optimizes one advantage or group of advantages as taught or
suggested herein without necessarily achieving other objects or
advantages as may be taught or suggested herein.
[0030] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments will
become readily apparent to those skilled in the art from the
following detailed description having reference to the attached
figures, the invention not being limited to any particular
disclosed embodiment(s).
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] These and other features, aspects, and advantages of the
present disclosure are described with reference to the drawings of
certain embodiments, which are intended to illustrate certain
embodiments and not to limit the invention.
[0032] FIG. 1 is a schematic diagram of an RF neurotomy system
being used to perform RF neurotomy on a patient.
[0033] FIG. 2A is a perspective view of an example embodiment of a
needle that may be used in an RF neurotomy procedure.
[0034] FIG. 2B is a cut away perspective view of a portion of the
needle of FIG. 2A.
[0035] FIG. 2C is a partial cut away and partial cross-sectional
view of a portion of another example embodiment of a needle that
may be used in an RF neurotomy procedure.
[0036] FIG. 2D is a perspective view of another example embodiment
of a needle that may be used in an RF neurotomy procedure.
[0037] FIG. 2E is a perspective view of an example embodiment of
filaments formed from a single wire.
[0038] FIG. 3A is a detailed view of an example embodiment of a
needle tip with filaments in a fully deployed position.
[0039] FIG. 3B is a detailed view of the needle tip of FIG. 3A with
filaments in a retracted position.
[0040] FIG. 3C is a detailed view of another example embodiment of
a needle tip with filaments in a deployed position.
[0041] FIG. 3D is a detailed view of another example embodiment of
a needle tip with filaments in a fully deployed position.
[0042] FIG. 3E is a detailed view of the needle tip of FIG. 3D with
filaments in a retracted position.
[0043] FIG. 3F is a cross-sectional view of the needle tip of FIG.
3D with filaments in a retracted position.
[0044] FIG. 3G is a detailed view of yet another example embodiment
of a needle tip with filaments in a deployed position.
[0045] FIGS. 3H and 3I are detailed views of still other example
embodiments of a needle tip with filaments in a deployed
position.
[0046] FIG. 4 is a schematic diagram of an example embodiment of an
RF probe assembly.
[0047] FIG. 5 is a proximal-facing end view of an example
embodiment of a needle tip.
[0048] FIG. 6 is a side view of an example embodiment of a needle
tip.
[0049] FIG. 7 is a proximal-facing end view of another example
embodiment of a needle tip.
[0050] FIG. 8 is a proximal-facing end view of yet another example
embodiment of a needle tip.
[0051] FIG. 9 is a proximal-facing end view of still another
example embodiment of a needle tip.
[0052] FIG. 10 is a side view of another example embodiment of a
needle tip.
[0053] FIG. 11A is an illustration of an example set of isotherms
that may be created with the needle of FIG. 2A.
[0054] FIG. 11B is an illustration of an example lesion that may be
created with the needle of FIG. 2A.
[0055] FIG. 11C is an illustration of an example lesion that may be
created with a single-filament needle.
[0056] FIG. 12 is a perspective view of the needle of FIG. 2A
positioned relative to a lumbar vertebra for performing RF
neurotomy.
[0057] FIG. 13 is an illustration of a sacrum including target
lesion volumes for performing Sacroiliac Joint (SIJ) RF
neurotomy.
[0058] FIG. 14 is a perspective view of the needle of FIG. 2A
positioned relative to a thoracic vertebra for performing RF
neurotomy.
[0059] FIG. 15 is a perspective view of the needle of FIG. 2A
positioned relative to the C2/3 cervical zygapophyseal joint (z
joint) for performing cervical medial branch RF neurotomy on the
third occipital nerve.
[0060] FIG. 16A is a perspective view of an example embodiment of a
needle tip.
[0061] FIG. 16B is a back elevational view of the needle tip of
FIG. 16A.
[0062] FIG. 16C is a front elevational view of the needle tip of
FIG. 16A,
[0063] FIG. 16D is a perspective view of an example embodiment of
an elongate member.
[0064] FIG. 16E is a perspective view of the needle tip of FIG. 16A
and the elongate member of FIG. 16D.
[0065] FIG. 16F is a cross-sectional view of the needle tip and
elongate member of FIG. 16E along the line 16F-16F of FIG. 16E and
example embodiments of a filament and an RF probe.
[0066] FIG. 16G is a cross-sectional view of another example
embodiment of a needle tip and elongate member and example
embodiments of a filament and an RF probe.
[0067] FIG. 17A is an exploded view of components of the deployment
mechanism of FIG. 2D.
[0068] FIG. 17B is a cross-sectional view of components of the
deployment mechanism of FIG. 2D.
[0069] FIG. 17C is a perspective view of an example embodiment of
an advancing hub and the wire of FIG. 2E.
[0070] FIG. 17D is a cross-sectional view of an example embodiment
of a spin collar.
[0071] FIG. 17E is a cross-sectional view of an example embodiment
of a main hub, taken along the line 17E-17E of FIG. 17B, in
exploded view with an example embodiment of an elongate member.
[0072] FIG. 18A is an axial view of posterior oblique needle
entry.
[0073] FIG. 18B is a saggital view of posterior oblique needle
entry.
DETAILED DESCRIPTION
[0074] Although certain embodiments and examples are described
below, those of skill in the art will appreciate that the invention
extends beyond the specifically disclosed embodiments and/or uses
and obvious modifications and equivalents thereof. Thus, it is
intended that the scope of the invention herein disclosed should
not be limited by any particular embodiments described below.
[0075] In the following description, the invention is set forth in
the context of apparatuses and methods for performing RF ablation.
More particularly, the systems and methods may be used to perform
RF neurotomy to ablate portions of target nerves. Even more
particularly, the systems and methods may be used to perform spinal
RF neurotomy to ablate portions of target nerves along the spine of
a patient to relieve pain. For example, embodiments of methods and
apparatuses described herein relate to lumbar RF neurotomy to
denervate a facet joint between the L4 and L5 lumbar vertebrae.
Denervation may be achieved by application of RF energy to a
portion of a medial branch nerve to ablate or cauterize a portion
of the nerve, thus interrupting the ability of the nerve to
transmit signals to the central nervous system. In another example,
embodiments described herein relate to sacroiliac joint RF
neurotomy.
[0076] FIG. 1 illustrates an example embodiment of a system 100 for
performing RF neurotomy on a patient 101. The patient 101 may be
positioned face down on a table or surface 109 to allow access
along the spine of the patient 101. Other patient orientations are
also possible depending on the procedure. The table 109 may
comprise radiolucent materials substantially transparent to x-rays,
such as carbon fiber.
[0077] The system 100 may include an RF generator 102 capable of
generating an RF energy signal sufficient to ablate target tissue
(e.g.: cause lesions in targeted volumes; cauterize targeted
portions of target nerves). The RF generator 102 may, for example,
be capable of delivering RF energy between about 1 W and about 200
W and between about 460,000 Hz and about 500,000 Hz. A needle 103
capable of conducting (e.g., transmitting or directing) RF energy
may be interconnected to the RF generator 102 and may be used to
deliver an RF energy signal to a specific site within the patient
101. In some embodiments in which the needle 103 is a monopolar
device, a return electrode pad 104 may be attached to the patient
101 to complete a circuit from the RF generator 102, through the
needle 103, through a portion of the patient 101, through the
return electrode pad 104, and back to the RF generator 102. In some
embodiments comprising a bipolar arrangement, the needle 103 may
comprise at least one supply electrode and at least one return
electrode to define the circuit.
[0078] The RF generator 102 may be operable to control the RF
energy emanating from the needle 103 in a closed-loop fashion. For
example, the needle 103 and/or an RF probe in the needle 103 may
include a temperature measurement device, such as a thermocouple,
configured to measure temperature at the target tissue. Data may
also be available from the RF generator 102, such as power level
and/or impedance, which may also be used for closed-loop control of
the needle 103. For example, upon detection of a temperature, a
parameter (e.g., frequency, wattage, application duration) of the
RF generator 102 may be automatically adjusted.
[0079] FIG. 4 illustrates an example RF probe assembly 400
compatible with the needle 103. The RF probe assembly 400 includes
an RF probe 401 that may be inserted into a patient (e.g., through
the needle 103) and may direct RF energy to the target tissue. In
some embodiments, the RF probe 401 may be in electrical
communication with the needle 103 to direct RF energy to the target
tissue, but is not inserted into the patient. The RF probe 401 may
include a thermocouple operable to measure temperature at a distal
end 402 of the RF probe 401. The RF probe assembly 400 may include
a connector 403 and a cable 404 configured to connect the RF probe
401 to an RF generator (e.g., the RF generator 102).
[0080] Returning to FIG. 1, the system 100 optionally includes an
imaging system 105 capable of producing internal images of the
patient 101 and the needle 103, for example to facilitate
navigation of the needle 103 during a procedure. The system 100 may
further include a display device for displaying the generated
images to a user performing the procedure. In some embodiments, the
imaging system 105 comprises a fluoroscope capable of generating
real-time two dimensional images of the needle 103 and internal
structures of the patient 101. In certain such embodiments, the
imaging system includes an X-ray source 106, an X-ray detector 107,
and a controller 108 in electrical communication with the X-ray
source 106 and/or the X-ray detector 107. The X-ray source 106 and
X-ray detector 107 may be mounted on a movable structure (e.g., a
C-arm), to facilitate capturing a variety of images of the patient
101 (e.g., at various angles or projection views). Other imaging
systems 105 are also possible (e.g., a computed tomography (CT)
scanner).
[0081] FIG. 2A illustrates an example embodiment of a needle 103
that may be used in the system 100 for performing RF neurotomy. The
needle 103 includes a tip 201 that tapers to a point 301 capable of
piercing the skin of a patient. In some embodiments, the tip point
tapers to a point substantially at the center of the tip 201 (e.g.,
a "pencil-point" tip). In some embodiments, the tip point tapers to
a point substantially at one side of the tip 201 (e.g., a "cutting"
or "beveled" or "lancet" or "Quincke" tip). The needle 103 further
includes an elongate member 203 connected to the tip 201 at a
distal end 202 of the needle 103 and connected to a hub 204 at a
proximal end 205 of the needle 103. The needle 103 includes a
longitudinal axis 223 along the center of the elongate member
203.
[0082] FIG. 2D illustrates another example embodiment of a needle
103 that may be used in the system 100 for performing RF neurotomy.
The needle 103 includes a tip 211 that tapers to a point 301
capable of piercing the skin of a patient. In some embodiments, the
tip point tapers to a point substantially at the center of the tip
211 (e.g., a "pencil-point" tip). In some embodiments, the tip
point tapers to a point substantially at one side of the tip 211
(e.g., a "cutting" or "beveled" or "lancet" or "Quincke" tip). The
needle 103 further includes an elongate member 203 connected to the
tip 211 at a distal end 202 of the needle 103 and connected to a
hub 204 at a proximal end 205 of the needle 103. The needle 103
includes a longitudinal axis 223 along the center of the elongate
member 203.
[0083] The needle 103 may include a self-contained mechanical
mechanism, in the form of deployable filaments 206a, 206b, operable
to expand the volume of effective RF energy delivery as compared to
known single-electrode RF probes. The filaments 206a, 206b may be
at least partially in the elongate member 203 and may be operable
to emerge through one or more apertures of the needle 103 proximate
to the distal end 202 of the needle 103. In some embodiments, the
needle 103 includes a single filament or three or more filaments.
The filaments 206a, 206b allow contraction/expansion, offsetting,
and/or contouring of the effective RF energy delivery over a
selected area of anatomy to adjust lesion geometry produced using
the needle 103 to match a desired target volume (e.g., spherical,
hemispherical, planar, spheroid, kidney-shaped, catcher's
mitt-shaped, oblong, snowman-shaped, etc.). The filaments 206a,
206b may be deployable and/or retractable by moving (e.g.,
rotating) an actuator 216 relative to the hub 204.
[0084] As will be further described, the needle 103 may further
include a tube 207 that includes a lumen 222 therethrough. The
lumen 222 may be used to transport fluids to and/or from the target
volume. The lumen 222 may also accept the RF probe 401 for delivery
of RF energy to the target volume. The lumen 222 may also accept a
dummy or temporary probe, for example to occlude the fluid port 210
during insertion. In some embodiments, the RF probe 401 is
integrated with the needle 103. In certain such embodiments, the
tube 207 need not be present for RF energy delivery, although it
may be included to facilitate fluid delivery. In some embodiments,
the filaments 206a, 206b include lumens therethrough for the
transportation of fluid to and/or from the target volume. In some
embodiments, the filaments 206a, 206b do not include lumens
therethrough (e.g., being solid). The filaments 206a, 206b may
function as thermocouples.
[0085] As RF energy penetrates biological tissue, protein and water
molecules oscillate in response to the RF current and the tissue
adjacent to the RF electrode is heated. As the tissue heats and
coagulates, the biophysical properties of the tissue change. These
tissue changes limit penetration of the RF energy beyond a leading
edge defined by the shape and size of an active needle tip.
Accordingly, the size of a radiofrequency lesion using conventional
single needle technology is practically limited after achievement
of a certain temperature delivered for a certain time.
[0086] A needle 103 with deployable filaments 206a, 206b can
overcome this obstacle and expand the effective area of RF energy
delivery by providing multiple locations (e.g., the tip 201, 211
the filament 206a, and/or the filament 206b) from which the RF
energy emanates. The use of multiple filaments 206a, 206b provides
additional conduits for RF energy, creating a multiple electrode RF
field effect. The size, shape, and location of a lesion created
with the needle 103 may be at least partially determined by, for
example, the quantity, angle, length, location, and/or orientation
of the filaments and RF energy parameters such as wattage,
frequency, and/or application duration, one or all of which may be
beneficially modified to suit a specific anatomical application by
changing various aspects of the filaments as discussed below.
[0087] Where it is desired to create a lesion offset from the
central longitudinal axis 223, the lesion may be offset in a
desired direction from the central longitudinal axis 223 by
rotationally orienting the needle 103. The needle 103 may be used
to create a lesion offset from the central longitudinal axis 223 in
a first direction. The filaments 206a, 206b may be retracted (e.g.,
after creating a first lesion), the needle 103 rotated, and the
filaments 206a, 206b re-deployed to create a lesion offset from the
central longitudinal axis 223 in a second direction (e.g., to
create a second lesion).
[0088] FIGS. 3A and 3B are detailed views of an example embodiment
of a distal end 202 of a needle 103 that includes a tip 201. The
tip 201 may include a sharpened point 301 (e.g., tapering to a
point substantially at the center of the tip 201, a pencil-point
tip) for piercing the skin of a patient and facilitating
advancement through tissue. The tip 201 may include a tapered
portion 302 that transitions the tip 201 from the point 301 to a
body portion 303. The body portion 303 is the portion of the tip
201 that is proximal to the tapered portion 302. The body portion
303 may be cylindrical as illustrated, or may be other appropriate
shapes The body portion 303 may have a cross-section that coincides
with (e.g., is coaxial with) the cross section of the elongate
member 203.
[0089] FIGS. 3D and 3E are detailed views of another example
embodiment of a distal end 202 of a needle 103 that includes a tip
211. The tip 211 may include a sharpened point 301 (e.g., tapering
to a point substantially at one side of the tip 201, a cutting or
beveled or lancet or Quincke tip) for piercing the skin of a
patient and facilitating advancement through tissue. The tip 211
may include a tapered portion 302 that transitions the tip 211 from
the point 301 to a body portion 303. The body portion 303 is the
portion of the tip 201 that is proximal to the tapered portion 302.
The body portion 303 may be cylindrical as illustrated, or may be
other appropriate shapes (e.g., as illustrated in FIG. 16A). The
body portion 303 may have a cross-section that coincides with
(e.g., is coaxial with) the cross section of the elongate member
203. In some embodiments, the tip 211 has a bevel angle between
about 10.degree. and about 45.degree., between about 15.degree. and
about 35.degree., between about 20.degree. and about 30.degree.
(e.g., about 25.degree.), combinations thereof, and the like. Other
bevel angles are also possible. In some embodiments, the point 301
has an angle between about 40.degree. and about 120.degree.,
between about 70.degree. and about 90.degree., between about
75.degree. and about 85.degree. (e.g., about 79.degree.),
combinations thereof, and the like. Other angles are also
possible.
[0090] The tip 201, 211, or a non-insulated portion thereof, may
act as an RF energy delivery element. The tip 201, 211 may comprise
(e.g., be made from) a conductive material such as, for example,
stainless steel (e.g., 300 Series Stainless Steel). The tip 201,
211 may be at least partially coated (e.g., with an insulator). The
material of the tip 201, 211 and the material of the optional
coating may be selected, for example, to act as an insulator,
improve radiopacity, improve and/or alter RF energy conduction,
improve lubricity, and/or reduce tissue adhesion.
[0091] The tip 201, 211 includes a first filament port or slot 304a
(not visible in the views of FIGS. 3A, 3B, 3D, and 3E) and a second
filament port or slot 304b. The geometry of the filament slots
304a, 304b may be selected to allow filaments 206a, 206b to be
adequately retracted (e.g., such that the filaments 206a, 206b are
in a cross-sectional envelope of the body portion 303 of the tip
201, 211, as shown in FIG. 3F) while the needle 103 is inserted
into the body, so that the filaments 206a, 206b do not cause any
unintended damage to the patient. Such positioning of the filament
slots 304a, 304b avoids having filament exit features on the
tapered portion 302 and thus avoids potential coring that could be
caused by such positioning.
[0092] The internal geometry of the filament slots 304a, 304b may
be designed such that the filaments 206a, 206b may be easily
retracted and advanced. For example, the internal geometry of the
filament slots 304a, 304b may include a transition region 305 that
meets the outer surface of the body portion 303 at an angle of
about 30.degree. The transition region 305 may, for example, be
curved and/or planar. Advancement of filaments 206a, 206b without a
pre-set bias (e.g., substantially straight) relative to the
filament slots 304a, 304b can causes the filaments 206a, 206b to be
deflected outwardly as the filaments 206a, 206b move distally along
the transition region 305. Depending on the positioning of the
transition region 305 relative to where the filaments 206a, 206b
are confined (e.g., in the needle 103 of FIG. 3A, the filaments
206a, 206b are confined to only longitudinal movement where they
enter into the elongate member 203) and on the mechanical
properties of the filaments 206a, 206b, various deployment angles
of the filaments 206a, 206b relative to the central longitudinal
axis 223 may be achieved. Generally, the portions of the filaments
206a, 206b that extend outwardly away from the filament slots 304a,
304b may be unrestrained and thus may take any appropriate form.
For example, where there is no pre-set bias, the portions of the
filaments that extend outwardly away from the filament slots 304a,
304b (and therefore from the tip) may be substantially straight,
such as shown in FIGS. 2A, 3A, 3C, 3D, 6, 11A-11C, and 14. For
another example, when there is a pre-set bias, the portions of the
filaments that extend outwardly away from the filament slots may
take any appropriate shape, such as, for example, curved as shown
in FIG. 10.
[0093] The radial orientation of the filament slots 304a, 304b may
be selected such that a center point between the filament slots
304a, 304b does not coincide (e.g., is not coaxial with) with the
central longitudinal axis 223. For example, as shown in FIGS. 2A,
3A, 3B, 3D, and 3E, the filament slots 304a, 304b may be positioned
such that they are about 120.degree. apart about the circumference
of the tip 201, 211. Other filament slot configurations may be
configured to achieve the filament placements discussed below. For
example, the filament slots 304a, 304b may be between about
45.degree. and about 180.degree. apart about the circumference of
the tip 201, 211, between about 90.degree. and about 180.degree.
apart about the circumference of the tip 201, 211, between about
90.degree. and about 150.degree. apart about the circumference of
the tip 201, 211, combinations thereof, and the like. Other angles
are also possible. These configurations may be achieved by varying,
for example, the quantity of filament slots, the placement of
filament slots about the circumference of the tip 201, 211, and/or
the placement of filament slots along the center longitudinal axis
223 to achieve the filament placements discussed below.
[0094] As noted herein, and illustrated in FIGS. 3A and 3B, the
needle 103 may comprise a tube 207 that includes a lumen 222
therethrough. The lumen 222 may be employed to accept the RF probe
401 for delivery of RF energy, for the transport of fluids, and/or
for occluding a fluid port 210. The tip 201, 211 may include a
fluid port 210 that may be in fluid communication with the lumen
222 via a channel through the tip 201, 211. In certain embodiments,
the lumen 222 is a dual-purpose lumen that can allow injection of
fluids and that can receive the distal end 402 of the RF probe 401
to deliver RF energy to the tip 201, 211, the filament 206a, and/or
the filament 206b. In some embodiments, the fluid port 210 is
longitudinally spaced from the tip 301 (e.g., by between about 1 mm
and about 3 mm). The fluid port 210 may be centrally located (e.g.,
as illustrated in FIG. 3D) or it may be located offset from the
center longitudinal axis 223 (e.g., as shown in FIGS. 2A and 3A).
The fluid port 210 may be used to transfer fluid between the region
of the tip 201, 211 and the proximal end 205 of the needle 103. For
example, during an RF neurotomy procedure, an anesthetic and/or an
image enhancing dye may be introduced into the region of tissue
around the tip 201, 211 through the fluid port 210. In some
embodiments, the fluid port 210 is located along the tapered
portion 302 of the tip 201, 211 (e.g., as illustrated in FIGS. 3A
and 3D). In some embodiments, the fluid port 210 is located along
the body portion 303 of the tip 201, 211.
[0095] FIG. 16A is a perspective view of an example embodiment of
the needle tip 211. In some embodiments, the needle 103 does not
comprise a tube 207, but the elongate member 203 comprises a lumen
308 therethrough and the tip 211 comprises a lumen 306c
therethrough. The lumen 308 and the lumen 306c may be employed to
accept the RF probe 401 for delivery of RF energy, for the
transport of fluids, and or for occluding the fluid port 210. In
certain embodiments, the lumen 308 and the lumen 306c are
dual-purpose lumens that can allow injection of fluids and that can
receive the distal end 402 of the RF probe 401 to deliver RF energy
to the tip 211, the filament 206a, and/or the filament 206b. The
filament lumens 306a, 306b may also allow liquid transfer from a
proximal end of the needle to the filament ports 304a, 304b.
[0096] In some embodiments, the filament lumens 306a, 306b are
sized to inhibit buckling and/or bending of the filaments in the
tip 211. In some embodiments, the elongate member 203 may also
include filament lumens (e.g., comprising tubes in the elongate
member 203). In some embodiments, filament lumens in the elongate
member 203 may be formed by an inner member (not shown) extending
at least part of the length of the elongate member 203. For
example, a transverse cross-section of the inner member may have
the same cross-section as the portion of the tip 211 illustrated in
FIG. 3F, including channels in which the filaments may lie and a
lumen for passing fluid, an RF probe 401, and/or a dummy probe.
[0097] FIG. 16B is a back elevational view of the needle tip 211 of
FIG. 16A. FIG. 16C is a front elevational view of the needle tip
211 of FIG. 16A. The needle tip 211 comprises a filament lumen 306a
in fluid communication with and terminating at the filament slot
304a, a filament lumen 306b in fluid communication with and
terminating at the filament slot 304b, and the lumen 306c. In some
embodiments, the lumens 306a, 306b are spaced by about 120.degree.
along the circumference of the tip 211. Other angles are also
possible. In some embodiments, the lumen 306c is spaced from each
of the lumens 306a, 306b by about 120.degree. along the
circumference of the tip 211. Other angles are also possible.
Referring again to FIG. 3F, the filament 206a may be in the
filament lumen 306a and the filament 206b may be in the filament
lumen 306b. The lumen 306c is in fluid communication with the fluid
port 210. In some embodiments, the proximal end of the tip 211
includes a tapered surface, as shown in FIG. 16A. When filaments
206a, 206b are in the filament lumens 306a, 306b, the tapered
surface may help to guide insertion of an RF probe 401 into the
lumen 306c. In some embodiments, the tapered surface has an angle
normal to the tip 211 between about 15.degree. and about
75.degree., between about 30.degree. and about 60.degree., between
about 40.degree. and about 50.degree. (e.g., about 45.degree.),
combinations thereof, and the like. Other angles are also
possible.
[0098] FIG. 16D is a perspective view of an example embodiment of
an elongate member 203. The elongate member 203 includes the lumen
308, the filament slot 304a, and the filament slot 304b. In some
embodiments, the filament slots 304a, 304b are spaced by about
120.degree. along the circumference of the elongate member 203.
FIG. 16E is a perspective view of the needle tip 211 of FIG. 16A
and the elongate member 203 of FIG. 16D. As described herein, the
elongate member 203 may be coupled to the tip 211 by adhering with
conductive epoxy, welding, soldering, combinations thereof, and the
like. A proximal portion of the tip 211 can be inserted into the
lumen 308 of the elongate member 203. The filament slot 304b of the
elongate member 203 is substantially aligned with the lumen 306b of
the tip 211, allowing the filament 206b to be deployed out of the
lumen 306b. Although not illustrated, the filament slot 304a of the
elongate member 203 is substantially aligned with the lumen 306a of
the tip 211, allowing the filament 206a to be deployed out of the
lumen 306a. In some embodiments, each of the filament slots 304a,
304b has a length between about 0.025 inches and about 0.2 inches
(approx. between about 0.6 mm and about 3 mm), between about 0.05
inches and about 0.15 inches (approx. between about 1.3 mm and
about 3.8 mm), between about 0.075 inches and about 0.125 inches
(approx. between about 1.9 mm and about 3.2 mm) (e.g., about 0.105
inches (approx. about 2.7 mm)), combinations thereof, and the like.
Other lengths are also possible. In some embodiments, each of the
filament slots 304a, 304b has a width between about 0.01 inches and
about 0.4 inches (approx. between about 0.25 mm and about 10 mm),
between about 0.02 inches and about 0.03 inches (approx. between
about 0.5 mm and about 0.76 mm), between about 0.015 inches and
about 0.025 inches (approx. between about 0.38 mm and about 0.64
mm) (e.g., about 0.02 inches (approx. about 0.5 mm)), combinations
thereof, and the like. Other widths are also possible. In some
embodiments, the each of the transition regions 305 has a length
between about 0.02 inches and about 0.2 inches (approx. between
about 0.5 mm and about 5 mm), between about 0.05 inches and about
0.15 inches (approx. between about 1.3 mm and about 3.8 mm),
between about 0.075 inches and about 0.125 inches (approx. between
about 1.9 mm and about 3.2 mm) (e.g., about 0.104 inches (approx.
about 2.6 mm)), combinations thereof, and the like. Other lengths
are also possible. In some embodiments in which the transition
regions include curved surfaces, the each of the transition regions
305 has a radius of curvature between about 0.01 inches and about
0.4 inches (approx. between about 0.25 mm and about 10 mm), between
about 0.15 inches and about 0.35 inches (approx. between about 3.8
mm and about 8.9 mm), between about 0.2 inches and about 0.3 inches
(approx. between about 5 mm and about 7.6 mm) (e.g., about 0.25
inches (approx. about 6.4 mm)), combinations thereof, and the like.
Other radii of curvature are also possible. Certain combinations of
dimensions of the transition regions 305 and filaments slots 304a,
304b described herein may cause deployment of the filaments 206a,
206b at desired angles (e.g., about 30.degree.).
[0099] The lumen 308 is not visible in FIG. 16E because the
elongate member 203 covers the lumen 308. Covering the lumen 308
causes fluid inserted into the lumen 308 to exit the fluid port
210, and possibly the filament slots 304a, 304b. In some
embodiments, for example as illustrated in FIGS. 3A and 3B, the
elongate member 203 may also include a slot proximate to the tube
207. In certain such embodiments, the tube 207 may extend distal to
the slot and substantially all fluid inserted into the lumen 222
exits the fluid port 210.
[0100] In the embodiment illustrated in FIG. 16E, the body portion
303 of the tip 211 and the elongate member 203, excluding the
sleeve 307, have substantially equal diameters, for example to
provide a smooth transition between the tip 211 and the elongate
member 203. In some embodiments, the elongate member 203 has an
inner diameter between about 0.01 inches and about 0.04 inches
(approx. between about 0.25 mm and about 1 mm), between about 0.015
inches and about 0.035 inches (approx. between about 0.38 mm and
about 0.89 mm), between about 0.02 inches and about 0.03 inches
(approx. between about 0.5 mm and about 0.76 mm) (e.g., about 0.025
inches (approx. about 0.64 mm)), combinations thereof, and the
like. Other diameters are also possible. In some embodiments, the
elongate member 203 has an outer diameter between about 0.01 inches
and about 0.05 inches (approx. between about 0.25 mm and about 1.3
mm), between about 0.02 inches and about 0.04 inches (approx.
between about 0.5 mm and about 1 mm), between about 0.025 inches
and about 0.035 inches (approx. between about 0.64 mm and about
0.89 mm) (e.g., about 0.029 inches (approx. about 0.74 mm)),
combinations thereof, and the like. Other diameters are also
possible. In some embodiments, the proximal portion of the tip has
an outer diameter between about 0.01 inches and about 0.04 inches
(approx. between about 0.25 mm and about 1 mm), between about 0.015
inches and about 0.035 inches (approx. between about 0.38 mm and
about 0.89 mm), between about 0.02 inches and about 0.03 inches
(approx. between about 0.5 mm and about 0.76 mm) (e.g., about 0.025
inches (approx. about 0.64 mm)), combinations thereof, and the
like. Other diameters are also possible. In some embodiments, the
tip 211 has an outer diameter between about 0.01 inches and about
0.05 inches (approx. between about 0.25 mm and about 1.3 mm),
between about 0.02 inches and about 0.04 inches (approx. between
about 0.5 mm and about 1 mm), between about 0.025 inches and about
0.035 inches (approx. between about 0.64 mm and about 0.89 mm)
(e.g., about 0.029 inches (approx. about 0.74 mm)), combinations
thereof, and the like. Other diameters are also possible.
[0101] FIG. 16F is a cross-sectional view of the needle tip 211 and
the elongate member 203 along the line 16F-16F of FIG. 16E. FIG.
16F also illustrates an example embodiment of a filament 206a in
the lumen 308 and the lumen 306a, then exiting via the filament
slot 304a, and an RF probe 401 in the lumen 308. In some
embodiments, the elongate member 203 and the tip each 211 comprise
(e.g., are each made from) a conductive material (e.g., 300 Series
Stainless Steel), and can conduct electrical signals from the RF
probe 401 to the tip 211 and the filaments 206a, 206b (e.g., due to
physical contact of conductive components) to form a monopolar
electrode. In some embodiments, the RF probe 401, the filaments
206a, 206b, the tip 211, and/or the elongate member 203 may include
features configured to increase physical contact between the
components. The cross-sectional view shows the lumen 308 in fluid
communication with the lumen 306c and the fluid port 210.
[0102] FIG. 16G is another cross-sectional view of an example
embodiment of a needle tip 211 and the elongate member 203 along a
line similar to the line 16F-16F in FIG. 16E. The tip 211 in FIG.
16G does not include a fluid port 210, but fluid can permeate out
of the filament slots 304a, 304b because the filament slots are in
fluid communication with the lumen 308. In some embodiments, the
tip 211 includes a lumen 306c, for example to assure placement of
or contact with the probe 401 (e.g., as illustrated in FIG. 16G).
In some embodiments, the tip 211 does not include a lumen 306c, for
example to reduce manufacturing costs if the lumen 306c is cut from
a solid tip stem.
[0103] As may be appreciated, the channel through the tip 201, 211
may be sized to accommodate a tip of the RF probe 401 that may be
inserted into the needle 103. The channel may be sized such that RF
energy from the inserted RF probe 401 is satisfactorily
communicated from the RF probe 401 to the tip 201, 211, the
filament 206a, and/or the filament 206b.
[0104] FIGS. 3C and 3G are each a detailed view of the distal end
310 of a needle 309 that is an alternate embodiment of the needle
103. The distal end 310 includes a tip 311, 321 that may include a
sharpened point 312 for piercing the skin of a patient and
facilitating advancement through tissue. The tip 311, 321 may
include a tapered portion 313 that transitions the tip 311, 321
from the point 312 to a first body portion 314. The first body
portion 314 may be connected to a second body portion 315 at an
angle 316. In some embodiments, the angle 316 is about 15.degree..
Other angles 316 are also possible. For example, the angle 316 may
be between about 5.degree. and about 90.degree., between about
10.degree. and about 60.degree., between about 10.degree. and about
45.degree., between about 10.degree. and about 20.degree.,
combinations thereof, and the like. Other angles are also possible.
The second body portion 315 may be aligned with an elongate member
317. The elongate member 317 may be similarly configured as the
elongate member 203 of FIGS. 3A, 3B, 3C, and 3D. The angle 316
between the first body portion 314 and the second body portion 315
may aid the user in navigating the needle 309 to a desired
position. For example, by rotating the needle 309 such that the
first body portion 314 is pointing in a desired direction,
subsequent advancement of the needle 309 may result in the needle
309 following a non-straight path biased toward the desired
direction.
[0105] The first and second body portions 314, 315 may be
cylindrical as illustrated, or they may be of any other appropriate
shape. The first and second body portions 314, 315 may have
cross-sections that coincide with (e.g., is coaxial with) the cross
section of the elongate member 317.
[0106] The tip 311, 321, or a non-insulated portion thereof, may
act as an RF energy delivery element. The tip 311, 321 may comprise
(e.g., be made from) a conductive material such as, for example,
stainless steel (e.g., 300 Series Stainless Steel). The tip 311,
321 may be coated (e.g., with an insulator). The material of the
tip 311, 321 and the material of the optional coating may be
selected, for example, to act as an insulator, improve radiopacity,
improve and/or alter RF energy conduction, improve lubricity,
and/or reduce tissue adhesion.
[0107] The filaments 319a, 319b may also act as RF energy delivery
elements. The filaments 319a, 319b may be constructed in a manner
similar to as described with respect to the filaments 206a,
206b.
[0108] The tip 311 of FIG. 3C includes a filament slot 318a and a
filament slot 318b. The geometry of the filament slots 318a, 318b
may be selected to allow filaments 319a, 319b to be adequately
retracted (e.g., such that they are in a cross-sectional envelope
of the second body portion 315) while the needle 309 is inserted
into the body, so that the filaments 319a, 319b do not cause any
unintended damage to the patient (e.g., by being along the second
body portion 315). Such positioning of the filament slots 318a,
318b may avoid having filament exit features on the tapered portion
313 and on the first body portion 314, which may avoid potential
coring. The internal geometry of the filament slots 318a, 318b may
include a transition region that meets the outer surface of the
second body portion 315 at an angle, and advancement of filaments
319a, 319b without a pre-set bias (e.g., substantially straight)
relative to the filament slots 318a, 318b can causes the filaments
319a, 319b to be deflected outwardly as the filaments 319a, 319b
move distally along the transition region.
[0109] The configuration and orientation of the filament slots
318a, 318b may be selected such that deployed filaments 319a, 319b
may achieve the positioning illustrated in FIG. 3C. In FIG. 3C, the
filaments 319a, 319b are generally positioned in a plane that is
perpendicular to a plane that includes the angle 316 between the
first and second body portions 314, 315. As illustrated, the
filaments 319a, 319b may be positioned such that they extend at an
angle (e.g., about 15.degree., between about 10.degree. and about
90.degree., between about 10.degree. and about 60.degree., between
about 10.degree. and about 45.degree., between about 10.degree. and
about 20.degree., combinations thereof, and the like) relative to
the plane that includes the angle 316. Other angles are also
possible Other filament slot 318a, 318b configurations may be
configured to achieve other desired filament 319a, 319b placements.
These configurations may be achieved, for example, by varying the
quantity of filament slots and filaments, the placement of filament
slots about the circumference of the tip 311, the angle at which
the filaments extend away from the first and second body portions
314, 315, and/or the placement of filament slots along the first
and second body portions 314, 315.
[0110] FIG. 3G illustrates an example embodiment of a tip 321 that
includes a filament slot 318a and a filament slot 318b along the
first body portion 314. The geometry of the filament slots 318a,
318b may be selected to allow filaments 319a, 319b to be adequately
retracted (e.g., such that they are in a cross-sectional envelope
of the second body portion 315) while the needle 309 is inserted
into the body, so that the filaments 319a, 319b do not cause any
unintended damage to the patient. Positioning of the filament slots
318a, 318b along the first body portion 314 may potentially cause
coring, so the filaments 319a, 319b may be configured to
substantially occlude the filament slots 318a, 318b, which may
avoid potential coring. The internal geometry of the filament slots
318a, 319b may lack a transition region and, due to being
positioned on the first body portion 314, advancement of the
filaments 319a, 319b without a pre-set bias (e.g., substantially
straight) can cause the filaments 319a, 319b to continue to advance
substantially straight (e.g., along the longitudinal axis of the
elongate member 317 and/or the second body portion 315) as the
filaments move distally out of the filament slots 318a, 318b.
Although not illustrated, placement of filament slots along the
tapered portion 313 is also possible (e.g., the filaments
continuing to advance along the longitudinal axis of the first body
portion 314). Although not illustrated, the embodiments depicted in
FIGS. 3A and 3D may be adapted so the filaments 206a, 206b exit
along the tapered portion 302.
[0111] The needle 309 may comprise a tube that includes a lumen
therethrough, for example as described herein with respect to FIGS.
3A, 3B, 3D, and 3E. The lumen may be employed to accept an RF probe
for delivery of RF energy and/or for the transport of fluids. In
this regard, the tip 311 may further include a fluid port 320 that
may be in fluid communication via a channel through the tip 311
with the lumen. The fluid port 320 may be used to transfer fluid
between the region of the tip 311 and a proximal end of the needle
309.
[0112] In the deployed position as shown in FIG. 3C, the distal
ends of the filaments 319a, 319b are disposed away from the point
312. In the deployed position as shown in FIG. 3G, the distal ends
of the filaments 319a, 319b are disposed away from the point 312.
In a retracted position (not shown, but similar to as shown in
FIGS. 3B and 3E), the distal ends of the filaments 319a, 319b are
entirely within an outer perimeter (e.g., circumference where the
second body portion 315 of the tip 311, 321 is round) of the tip
311, 321. In the deployed position, the filaments 319a, 319b act as
broadcast antennae for an RF probe inserted into the needle 309.
The tip 311 or 321, the filament 319a, and/or the filament 319b may
form a monopolar electrode for application of RF energy to the
target volume. The filaments 319a, 319b may allow the RF energy
from the RF probe to be dispersed over a larger volume than would
be possible with the tip 311, 321 alone.
[0113] In general, any or all of the herein variables may be
incorporated into a particular embodiment of a needle to yield a
needle capable of producing a lesion with a particular size,
position and shape relative to the tip of the needle. Such custom
sizes, positions and shapes may be designed for specific
procedures. For example, a particular lesion size, position and
shape may be selected to enable a user to navigate the needle to a
particular landmark (e.g., proximate to or touching a bone visible
using fluoroscopy) and then orient the needle such that deployed
filaments will be operable to produce a lesion at a particular
location relative to the landmark. By navigating to a particular
internal landmark, as opposed to attempting to visualize a relative
position of a needle offset from a landmark, a more accurate and/or
consistent positioning of the needle may be achieved. In this
regard, the skill level required to accurately position the needle
for a particular procedure may be reduced.
[0114] The lesion shapes achievable through selection of the herein
variables may include, for example, generally spherical, oblong,
conical, and pyramidal shapes. The orientation relative to, and the
amount of offset from, the tip of such shapes may be selectable. In
an embodiment, the tips of the deployed filaments may be positioned
distally relative to the point of the tip to provide for a facile
positioning of the lesion relative to the tip. Such capability may
allow for the needle to be inserted directly toward a target
volume. In other embodiments, the tips of the deployed filaments
may be positioned at the same axial position along the central
longitudinal axis as the point of the tip or the tips of the
deployed filaments may be positioned proximally relative to the
point of the tip. In other embodiments, some filament endpoints may
be located distal to the point of the tip while others are proximal
to the point of the tip.
[0115] The elongate member 203 may be in the form of a hollow tube
(e.g., sheath, cannula) interconnecting the tip 201, 211 with the
hub 204. The elongate member 203 may be configured with adequate
strength to allow the needle 103 to pierce a patient's skin and
advance to a target area through various tissue types, including,
for example, fat and muscle tissue. The elongate member 203 may
also be capable of resisting kinking as it is advanced. In some
embodiments, the elongate member 203 comprises a rod with a
plurality of lumens along its length to accommodate the filaments
206a, 206b, the RF probe 401, and/or a fluid passage.
[0116] The elongate member 203 houses portions of the filaments
206a, 206b and the tube 207, and allows for relative movement of
the filaments 206a, 206b. The elongate member 203 may be of any
appropriate size and internal configuration to allow insertion into
a patient and to house componentry therein. In some embodiments,
the elongate member 203 is a 16 gauge round tube or smaller. For
example, the elongate member 203 may be 18 gauge or 20 gauge. In
some embodiments, the elongate member 203 has a maximum
cross-sectional dimension of about 1.7 mm. In some embodiments, the
elongate member 203 has a maximum cross-sectional dimension of
about 1 mm. The elongate member 203 may have a length selected for
performing a specific spinal RF neurotomy procedure on a particular
patient. In some embodiments, the elongate member 203 has a length
of about 10 cm.
[0117] In certain embodiments, the elongate member 203 comprises
(e.g., is constructed from) an insulative material to reduce (e.g.,
eliminate) the amount of RF energy emitted along the length of the
elongate member 203 when the RF probe 401 is disposed therein. For
example, the elongate member 203 may comprise (e.g., be constructed
from) polymeric, ceramic, and/or other insulative material. In
certain embodiments, the elongate member 203 includes an insulating
coating or sleeve 307 (FIGS. 2D and 16D). In some embodiments, the
elongate member is insulated (e.g., constructed from insulative
material and/or having an insulating coating 307) except for a
distal part having a length between about 5 mm and about 10 mm.
FIG. 3H illustrates an example embodiment of a needle 309
comprising an insulating coating 330 covering a proximal portion of
the tip 321 and coatings 332a, 332b covering a proximal portion of
the filaments 319a, 319b. The coating 330 insulates, inter alia,
the bent area between the first body portion 314 and the second
body portion 315 if the tip 321.
[0118] In some embodiments, the elongate member is insulated (e.g.,
constructed from insulative material and/or having an insulating
coating) except for a proximal part. FIG. 3I illustrates an example
embodiment of a needle 309 comprising an insulating coating 330
covering a distal portion of the tip 321 and coatings 332a, 332b
covering a distal portion of the filaments 319a, 319b. In some
embodiments in which the distal portion of the tip 321 is, the
needle 309 may create a kidney or catcher's mitt shaped lesion,
which may be useful, for example, for ablating tissue where the
active tip is pressed against the wall of a structure with the
device staying in the lumen of a structure. For example, when
ablating endocardial lesions in which the device accesses the
target through a cardiac chamber, insulating the distal portion of
the tip 321, which stays in the chamber, can make the biophysics of
the lesion (e.g., impedance, power, heat) more precise because the
insulated distal portion of the tip 321 that is surrounded by blood
in the chamber will not be part of the field.
[0119] FIGS. 3H and 3I illustrate example embodiments of insulation
of parts of the tip 321 and the filaments 319a, 319b illustrated in
FIG. 3G. Parts of components of the distal ends of other needle
tips described herein may also be insulated (e.g., those
illustrated in FIGS. 3A, 3C, and 3D). In some embodiments, only
parts of the tip 321, and not parts of the filaments 319a, 319b,
are insulated. In some embodiments, only parts of the filaments
319a, 319b, and not parts of the tip 321, are insulated. In some
embodiments, a distal portion of the tip 321 is insulated (e.g., as
illustrated in FIG. 3I) and proximal portions of the filaments
319a, 319b are insulated (e.g., as illustrated in FIG. 3H). In some
embodiments, a distal portion of the filaments 319a, 319b are
insulated (e.g., as illustrated in FIG. 3I) and a proximal portion
of the tip 321 is insulated (e.g., as illustrated in FIG. 3H). In
some embodiments, the insulative coating or sleeve 330, 332a, 332b
may be adjustable. For example, one or all of the sleeves 330,
332a, 332b may be advanced or retracted relative to the tip 321,
the filament 319a, and the filament 319b, respectively, to increase
or decrease the amount of exposed conductive area.
[0120] The elongate member 203 may include a coating that may
improve radiopacity to aid in visualization of the position of the
needle 103 using fluoroscopy. The elongate member 203 may include a
lubricious coating to improve its ability to be inserted and
positioned in the patient and/or to reduce tissue adhesion. The
elongate member 203 may include markers 224 along its length to
assist in determining the depth to which the needle 103 has entered
into the anatomy. The markers 224 may be radiopaque so that they
may be viewed under fluoroscopy. A collar (not shown) may be
disposed about the elongate member 203 to assist in placement of
the tip 201, 211 of the needle 103. For example, the tip 201, 211
may be positioned in a first position, the collar may then be
placed against the patient's skin, and then the needle 103 may be
advanced and/or withdrawn a certain distance. Such a distance may
be indicated, for example, by the distance between the collar and a
patient's skin or other anatomy.
[0121] The elongate member 203 may be fixedly interconnected to the
tip 201, 211 and the hub 204 in any appropriate manner. For
example, the tip 201, 211 may be press fit into the elongate member
203 and the elongate member 203 may be press fit into the hub 204.
Other example methods of attachment include adhesive bonding and
welding. In some embodiments, the elongate member 203 and the tip
201, 211 are a single unitary structure. The elongate member 203
may be steerable and incorporate controlling mechanisms allowing
the elongate member 203 to be deflected or steered after insertion
into the anatomy.
[0122] The tube 207 containing the lumen 222 may comprise (e.g., be
constructed from) any appropriate material. For example, the tube
207 comprise a conductive material, such as stainless steel (e.g.,
300 Series Stainless Steel), such that when the RF probe 401 is
inserted in the tube 207, the RF energy emitted by the RF probe 401
may be conducted through the tube 207 and into and through the tip
201, 211, the filament 206a, and/or the filament 206b. The tube 207
may be interconnected to the tip 201, 211 such that the lumen 222
is in sealed, fluid communication with the channel through the tip
201, 211. This may be accomplished by a press fit, weld, or any
other appropriate method.
[0123] As noted, the lumen 222 may be in fluid communication with
the tip 201, 211 at the distal end 202. A proximal end of the lumen
222 may be disposed at the proximal end 205 of the needle 103. In
this regard, the lumen 222 may extend from the distal end 202 to
the proximal end 205, with the only access being at the distal and
proximal ends 202, 205. In some embodiments, the lumen 222 is the
only lumen of the needle 103 disposed along the elongate member
203.
[0124] The RF probe 401 inserted into the lumen 222 may be
positioned such that an end of the RF probe 401 is proximate to the
tip 201, 211. For example, the RF probe 401 may be positioned such
that the distal end 402 of the RF probe 401 is in the lumen 222
near the tip 201, 211 or in the channel through the tip 201, 211.
RF energy transmitted through the RF probe 401 may then be
conducted by the tip 201, 211, the filament 206a, and/or the
filament 206b. The size of the lumen 222 may be selected to
accommodate a particular size of RF probe 401. For example, the
lumen 222 may be configured to accommodate at least a 22 gauge RF
probe 401, at least a 21 gauge RF probe 401, or a larger or smaller
RF probe 401. For another example, the lumen 222 may have a maximum
cross-sectional dimension of less than about 0.85 mm.
[0125] The proximal end of the tube 207 may be operable to receive
the RF probe 401. The proximal end of the tube 207 and the actuator
216 may be configured to accept a connector, such as a Luer
fitting, such that a fluid source may be connected to the tube 207
(e.g., to deliver fluid through the lumen 222 and out the fluid
port 210).
[0126] The needle 103 includes two filaments 206a, 206b in and
along elongate member 203. Distal ends of the filaments 206a, 206b
are proximate to the tip 201, 211, and proximal ends of the
filaments 206a, 206b are fixed to a filament hub 221 discussed
below. The filaments 206a, 206b are movable along the central
longitudinal axis 223 between a fully deployed position as
illustrated in FIGS. 3A, 3C, 3D, and 3F and a retracted position
illustrated in FIGS. 3B and 3E. Moving the filaments 206a, 206b
distally from the retracted position moves the filaments 206a, 206b
toward the fully deployed position, while moving the filaments
206a, 206b proximally from the deployed position moves the
filaments 206a, 206b toward the retracted position. The filaments
206a, 206b may be deployed in intermediate positions between the
fully deployed positions and the retracted positions. For example,
a mechanism for advancement and/or retraction of the filaments
206a, 206b may include detents indicating partial deployment and/or
retraction and a stop indicating full deployment and/or
retraction.
[0127] In the fully deployed position, the distal ends of the
filaments 206a, 206b, 319a, 319b are disposed away from the tip
201, 211, 311, 321. In the retracted position, the distal ends of
the filaments 206a, 206b, 319a, 319b are entirely within an outer
perimeter (e.g., circumference where the body portion 303 of the
tip 201, 211, 311, 321 is round) of the tip 201, 211, 311, 321. In
the deployed position, the filaments 206a, 206b, 319a, 319b can act
as broadcast antennae for the RF probe 401 (e.g., RF energy passes
from the RF probe 401 to the tip 201, 211, 311, 321 and to the
filaments 206a, 206b, 319a, 319b, and into a target volume within a
patient). In this regard, together, the RF probe 401 inserted into
the lumen 222, the tip 201, 211, 311, 321, and the filaments 206a,
206b, 319a, 319b, may form a monopolar electrode for application of
RF energy to the target volume. The filaments 206a, 206b, 319a,
319b allow the RF energy from the RF probe 401 to be dispersed over
a larger volume than would be possible with the tip 201, 211, 311,
321 alone.
[0128] The filaments 206a, 206b, 319a, 319b may be constructed from
a material operable to conduct RF energy, e.g., a metal such as
stainless steel (e.g., 303 Stainless Steel), Nitinol, or shape
memory alloy. The filaments 206a, 206b may be coated, for example
to enhance and/or inhibit their ability to conduct RF energy. The
filaments 206a, 206b may include a lubricious coating to aid in
insertion and/or reduce tissue adhesion.
[0129] FIG. 2E illustrates an embodiment in which the filaments
206a, 206b are formed from a single wire 206 that is bent at the
proximal end. The distal ends of the filaments 206a, 206b are shown
as bent, which can be the result of deflection upon exit from a tip
201, 211, shape memory, combinations thereof, and the like. Forming
the filaments 206a, 206b from a single wire 206 may provide
advantages such as, for example, coherent activation of the
filaments 206a, 206b, simultaneous deployment of the filaments
206a, 206b, and/or simultaneous retraction of the filaments 206a,
206b. It will be appreciated that the wire 206 may be a single wire
or a plurality of wire segments joined together (e.g., via adhering
with conductive epoxy, welding, soldering, combinations thereof,
and the like). Other filaments described herein may also be coupled
or bent at the proximal end. The filaments 206a, 206b illustrated
in FIG. 2E are substantially parallel, and taper outwards before
being bent at the proximal end. In some embodiments, the filaments
206a, 206b are substantially parallel and do not taper out before
being bent at the proximal end. In certain such embodiments, the
proximal end of the wire 206 is a semi-circle, for example having a
radius between about 0.03 inches and about 0.07 inches (approx.
between about 0.76 mm and about 1.8 mm), between about 0.04 inches
and about 0.06 inches (approx. between about 1 mm and about 1.5
mm), between about 0.05 inches and about 0.055 inches (approx.
between about 1.3 mm and about 1.4 mm) (e.g., about 0.052 inches
(approx. about 1.32 mm)), combinations thereof, and the like. In
some embodiments, the filaments 206a, 206b are parallel and spaced
by a distance between about 0.025 inches and about 0.125 inches
(approx. between about 0.64 mm and about 3.2 mm), between about
0.05 inches and about 0.1 inches (approx. between about 1.3 mm and
about 2.5 mm) (e.g., about 0.075 inches (approx. about 1.9 mm)),
combinations thereof, and the like. In some embodiments, the
filaments 206a, 206b in the elongate member 203 may be braided,
wrapped, or twisted together. Such embodiments may increase column
strength, providing resistance to buckling and/or bending in the
elongate member 203. In some embodiments, the wire 206 has a
diameter between about 0.0025 inches and about 0.04 inches (approx.
between about 0.06 mm and about 1 mm), between about 0.005 inches
and about 0.025 inches (approx. between about 0.13 mm and about
0.64 mm), between about 0.01 inches and about 0.02 inches (approx.
between about 0.25 mm and about 0.5 mm) (e.g., about 0.014 inches
(approx. about 0.36 mm)), combinations thereof, and the like. Other
diameters are also possible. In some embodiments, the filaments
206a, 206b each have a diameter between about 0.0025 inches and
about 0.04 inches (approx. between about 0.06 mm and about 1 mm),
between about 0.005 inches and about 0.025 inches (approx. between
about 0.13 mm and about 0.64 mm), between about 0.01 inches and
about 0.02 inches (approx. between about 0.25 mm and about 0.5 mm)
(e.g., about 0.014 inches (approx. about 0.36 mm)), combinations
thereof, and the like. Other diameters are also possible. In some
embodiments, the filaments 206a, 206 have different diameters
(e.g., by being formed from different wires, by being formed from
portions of wires with different diameters that are coupled to form
the wire 206, etc.).
[0130] The distal ends of the filaments may be shaped (e.g.,
pointed) to improve their ability to move through tissue. For
example, the tips of the filaments 206a, 206b in FIG. 3A have an
outward-facing bevel. In some embodiments, the bevel is at an angle
between about 15.degree. and about 45.degree., between about
20.degree. and about 40.degree., between about 25.degree. and about
35.degree. (e.g., about 30.degree.), combinations thereof, and the
like. In embodiments in which the filaments 206a, 206b each have a
diameter of about 0.014 inches (approx. about 0.36 mm) and a bevel
of about 30.degree., the length of the bevel is about 0.024 inches
(approx. about 0.61 mm). The tips of the filaments 206a, 206b may
have the same shape (e.g., beveled) or different shapes. For
another example, the tips of the filaments 206a, 206b in FIG. 3D
have an inward-facing bevel. In certain embodiments, bevels (e.g.,
inward-facing bevels) can help to induce splay between the tips of
the filaments 206a, 206b (e.g., splay of between about 15.degree.
and about 20.degree.) by tracking to one side (e.g., away from the
beveled side) upon deployment, which can improve placement of the
filaments 206a, 206b. For yet another example, the tips of the
filaments 319a, 319b in FIG. 3G have a pencil-point. In certain
embodiments, a pencil-point tip can help to reduce splay between
the tips of the filaments 206a, 206b by substantially straight
tracking deployment, which can improve placement of the filaments
206a, 206b. In some embodiments, the filaments 206a, 206b comprise
materials with different tensile strength and/or rigidity, and the
filaments 206a, 206b, which can affect their ability to flex due to
contact with tissue and thus the amount of splay, if any. In
certain embodiments in which the filaments 206a, 206b comprise a
shape memory material, the deflection to an unconfined state may
work with or against the shapes of the tips. In some embodiments,
certain filament tips may help to occlude filaments slots, improve
interaction with a transition region, etc. Although certain
combinations of filament tips are illustrated with respect to
certain embodiments herein, the various shapes of the filament tips
described herein and otherwise may be selected for any of these
embodiments (e.g., the filaments 206a, 206b of FIG. 3A may have
inwardly-facing bevels or pencil-point tips, the filaments 206a,
206b of FIG. 3D may have outwardly-facing bevels or pencil-point
tips, the filaments 319a, 319b of FIG. 3C may have inwardly-facing
bevels or pencil-point tips, the filaments 319a, 319b of FIG. 3G
may have inwardly-facing bevels or outwardly-facing bevels,
etc.).
[0131] The positioning of the filaments 206a, 206b of the
embodiments illustrated in FIGS. 3A and 3D will now be described in
relation to FIG. 5. FIG. 5 is an end view of the tip 201 and
deployed filaments 206a, 206b of the embodiment illustrated in
FIGS. 2A and 3A. The filaments 206a, 206b are positioned at a
filament angle 503 of about 120.degree. apart from each other about
the central longitudinal axis 223. This coincides with the
positions of the filament slots 304a, 304b discussed herein since
the filaments 206a, 206b emerge from the filament slots 304a, 304b.
Other filament angles 503 are also possible. For example, the
filament angle 503 may be between about 90.degree. and about
180.degree., between about 90.degree. and about 150.degree.,
between about 100.degree. and about 140.degree., between about
110.degree. and about 130.degree., combinations thereof, and the
like. A filament-free angle 504 of about 240.degree. is defined as
the largest angle about the circumference of the tip 201, 211 that
is free of filaments. In an embodiment consisting of two filaments
206a, 206b, the filament angle 503 may be less than 180.degree. and
the filament-free angle 504 may be correspondingly greater than
180.degree. (e.g., greater than 200.degree. or greater than
240.degree.).
[0132] In FIG. 5, the central longitudinal axis 223 is
perpendicular to the plane of the illustration. A midpoint 502 is
defined between distal ends 501a, 501b of the filaments 206a, 206b,
respectively. The midpoint 502 is offset from the central
longitudinal axis 223. For example, in some embodiments, the
midpoint 502 is offset from the central longitudinal axis 223 by
about 2 mm. Other offset values are also possible. For example, the
offset may be between about 0.5 mm and about 5 mm, between about 1
mm and about 4 mm, between about 1 mm and about 3 mm, greater than
about 0.5 mm, less than about 5 mm, combinations thereof, and the
like. When RF energy is transmitted from the tip 201 and both of
the filaments 206a, 206b, the RF energy will be transmitted
asymmetrically with respect to the central longitudinal axis 223
the cause the RF energy will be emitted from the tip 201 and the
filaments 206a, 206b. As oriented in FIG. 5, the energy will be
biased in an upward direction in the direction from the point 301
toward the midpoint 502. Thus, when RF energy is transmitted during
an RF neurotomy procedure, a lesion will be created that is
correspondingly offset from the central longitudinal axis 223 in
the direction from the point 301 toward the midpoint 502.
[0133] Referring again to the asymmetric nature of the lesion, the
lesion may be substantially a three-dimensional polygon (e.g., with
rounded edges) of known dimensions and volume that is offset from
the central cannula in a known and predictable way. Different
embodiments may have different three-dimensional polygonal
structures adapted to the intended ablation target. By contrast,
needles without deployable filaments may be used to create
asymmetric planar lesions by varying needle insertion during the
ablation procedure, and may require substantial ablation volume
overlap.
[0134] FIG. 6 is a side view of the tip 201 and the filaments 206a,
206b, oriented such that the deployed filament 206b is entirely
within the plane of the figure. The filaments 206a, 206b extend
from the tip 201 at a common distance, or location, along the
central longitudinal axis 223. In some embodiments, the filaments
206a, 206b may extend different distances. The filament 206b is
deflected radially outwardly from the central longitudinal axis
223. The filament 206b emerges from the tip 201 at an angle 601 of
about 30.degree. from the central longitudinal axis 223, which is
parallel to the longitudinal axis of the elongate member 203. The
angle 601 may vary, for example, based at least partially on
positioning of a transition region 305, mechanical properties of
the filament 206b (e.g., shape-memory properties or lack thereof),
and the like. In some embodiments, the angle 601 is between about
5.degree. and about 85.degree., between about 10.degree. and about
60.degree., between about 20.degree. and about 40.degree., greater
than about 5.degree., less than about 85.degree., combinations
thereof, and the like. In some embodiments, the angle 601 is
related to the angle 503. For example, the angle 601 may be a
fraction of the angle 503, such as about 1/4. In some embodiments,
the angle 601 is unrelated to the angle 503, for example both being
independently chosen to produce a certain lesion size or shape. In
some embodiments, the distal tips 501a, 501b are positioned
distally beyond the point 301 by a distance 602, are disposed at a
distance 603 from the central longitudinal axis 223, and/or are
disposed at a distance 604 from each other. In some embodiments,
the distance 602 is about 3.5 mm, the distance 603 is about 3 mm,
and/or the distance 604 is about 4.5 mm. Other distances are also
possible. For example, in some embodiments, the distance 602 is
between about 0.5 mm and about 6 mm, between about 1 mm and about 5
mm, between about 3 mm and about 4 mm, combinations thereof, and
the like. Other distances are also possible. For another example,
in some embodiments, the distance 603 is between about 0.5 mm and
about 6 mm, between about 1 mm and about 5 mm, between about 2 mm
and about 4 mm, combinations thereof, and the like. Other distances
are also possible. For yet another example, in some embodiments,
the distance 604 is between about 2 mm and about 7 mm, between
about 3 mm and about 6 mm, between about 4 mm and about 5 mm,
combinations thereof, and the like. Other distances are also
possible.
[0135] The angles described herein (e.g., the angles 503, 601) may
be measured with respect to a needle 103 in a deployed state
outside of a patient's body, and that the angles may when the
needle is inside a patient's body, for example based at least in
part on splay of filaments due to beveling.
[0136] The tip 211 and deployed filaments 206a, 206b of the
embodiment illustrated in FIG. 3D may also have a filament angle
503, a filament-free angle 504, a midpoint 502, an angle 601,
distances 602, 603, 604, and other features described herein, for
example with respect to FIGS. 5 and 6. In some embodiments, the
portion of the lesion based at least partially on RF energy emitted
by the tip 211, and thus the shape of the lesion, may vary based on
the position of the point 301 (e.g., in FIG. 3d, the point 301 is
on the side of the tip 211 that comprises the filaments 206a,
206b).
[0137] The configuration of the filaments 206a, 206b illustrated in
FIGS. 2A, 3A, 3D, 5, and 6 may be operable to produce lesions that
are radially offset from the central longitudinal axis 223 and
distally offset from the point 301 as compared to a lesion created
by the tip 201, 211 without the filaments or a lesion created with
the needle 103 with the filaments 206a, 206b in the retracted
position.
[0138] Variations in the relative shapes, positions, and sizes of
lesions created with the needle may be achieved by repositioning
the filaments. For example, as noted herein, the lesion produced by
the needle will be in different positions depending on whether the
filaments are in the deployed or retracted positions. Lesions
having intermediate shapes, positions, and/or sizes may be achieved
by positioning the filaments in intermediate positions between the
fully deployed (e.g., as illustrated in FIGS. 3A, 3C, 3D, and 3G)
and fully retracted positions (e.g., as illustrated in FIGS. 3B and
3E). As noted herein, the needle with deployed filaments is
operable to produce larger lesion volumes than the needle with
retracted filaments. For example, the needle with fully deployed
filaments may be operable to produce lesion volumes of about 500
mm.sup.3. Other lesion volumes are also possible. For example, the
needle with fully deployed filaments may be operable to produce
lesion volumes between about 100 mm.sup.3 and about 2,000 mm.sup.3,
between about 200 mm.sup.3 and about 1,000 mm.sup.3, between about
250 mm.sup.3 and about 750 mm.sup.3, between about 400 mm.sup.3 and
about 600 mm.sup.3, combinations thereof, and the like.
[0139] Further variation in the shape, position, and/or size of
lesions created by needles with deployable filaments may be
achieved by different configurations of filaments. Variations may
include, for example, variations in materials, the number of
filaments, the radial positioning of the filaments, the axial
positioning of the filaments, the length of the filaments, the
angle at which the filaments exit the tip, the shape of the
filaments, etc. By varying these parameters, the needle may be
configured to produce lesions of various sizes and shapes that are
positioned at various locations relative to the tip. Such
variations may be specifically tailored to be used in specific
procedures, such as RF neurotomy procedures of particular nerves
adjacent to particular vertebrae.
[0140] Variations of the materials used for the tip and/or the
filaments may be selected to achieve particular lesion sizes,
positions, and/or shapes. For example, the tip may comprise (e.g.,
be made form) a material that does not conduct RF energy, in which
case RF energy from the RF probe 401 may be conducted by
substantially only the deployed filaments. In certain such
embodiments, emitting RF energy from the filaments may provide for
a lesion with a larger offset from the central longitudinal axis
223 than would be produced if the tip conducts RF energy and acts
as an electrode along with the filaments.
[0141] Another material-related variation that may affect lesion
shape, size, and/or position is the addition and placement of
insulation over the tip and/or over the filaments. For example, by
placing a layer of insulation over a proximal part of the portions
of the filaments that extend from the tip when in the deployed
position, the shape of the lesion may be altered since RF energy
may primarily emanate from the distal, non-insulated part of the
filaments. For another example, by placing a layer of insulation
over a proximal part of the tip, the shape of the lesion may be
altered since RF energy may primarily emanate from the distal,
non-insulated part of the tip. Other parts of the filaments and/or
tip may also be covered by an insulating material, for example a
distal part of the filaments and/or tip, an intermediate part of
the filaments and/or tip, combinations thereof, and the like, for
example as described with respect to FIGS. 3H and 3I.
[0142] Moreover, the materials used in making the filaments and tip
may be selected based on RF conductivity. For example, by using a
material for the tip that is less conductive of RF energy, the
proportion of RF energy emanating from the tip as compared to that
emanating from the filaments may be altered resulting in a
corresponding change in lesion size, position and/or shape.
[0143] The RF needles and RF probes discussed herein may be
constructed from materials that are Magnetic Resonance Imaging
(MRI) compatible (e.g., titanium, aluminum, copper, platinum,
non-magnetic 300 Series Stainless Steel, etc.). In certain such
embodiments, MRI equipment may be used to verify the positioning of
the needles and/or portions thereof and/or monitor the progress of
an ablation procedure (e.g., RF neurotomy).
[0144] Variations of the number of filaments used for needle may be
selected to achieve particular lesion sizes, positions and/or
shapes. For example, as illustrated in FIG. 7, a third filament 701
may extend from the tip 201' (or other tips described herein such
as the tip 211) in a position between filaments 206a, 206b. The
tips 501a, 501b of the filaments 206a, 206b and a tip 702 of
filament 701 may form a polygon 703 that has a centroid 704. The
centroid 704 is offset from the central longitudinal axis 223. Such
an arrangement may produce a lesion that is offset from the central
longitudinal axis 223 to a different degree than, and shaped
differently than, a lesion created by the needle of FIG. 5. In
general, where a centroid of a polygon formed by the tips of
filaments (or, in the case where there are two filaments, the
midpoint between them) is offset from the central longitudinal axis
223, a lesion created by such a configuration will be
correspondingly offset from the central longitudinal axis 223. The
filaments 206a, 206b, 702 are positioned at the same filament angle
503 of about 120.degree. as in the embodiment of FIG. 5. Other
filament angles 503, in either FIG. 5 or FIG. 7, are also possible.
The embodiment illustrated in FIG. 7 has a filament-free angle 504
of about 240.degree., also the same as in the embodiment of FIG. 5.
Other filament-free angles 504, in either FIG. 5 or FIG. 7, are
also possible. In general, in embodiments in which the filaments
are positioned in a filament angle 503 that is less than about
180.degree., resultant lesions will be offset from the central
longitudinal axis 223 in the direction of the filaments. In
embodiments in which the filaments are positioned in a filament
angle 503 that is less than about 180.degree., the filament-free
angle is correspondingly greater than about 180.degree. (e.g.,
greater than about 200.degree. or greater than about
240.degree.).
[0145] For another example, as illustrated in FIG. 8, four
filaments 801a-801d are positioned about a tip 201'' (or other tips
described herein such as the tip 211). The tips of the filaments
801a-801d may form a polygon 802 that has a centroid 803. The
centroid 803 is offset from the central longitudinal axis 223. Such
an arrangement may produce a lesion that is offset from the central
longitudinal axis 223 in the direction of the centroid 803. The
filaments 801a-801d are positioned at a filament angle 804 of about
200.degree.. Other filament angles 804 are also possible. The
embodiment illustrated in FIG. 8 has a filament-free angle 805 of
about 160.degree.. Other filament-free angles 805 are also
possible. FIG. 8 illustrates an embodiment in which the
filament-free angle 805 is less than about 180.degree., but which
is capable of producing a lesion offset from the central
longitudinal axis 223.
[0146] In the herein-described embodiment of FIGS. 2A, 3A, 3B, 5,
and 6 with two filaments, a midpoint 502 between the filaments was
discussed. In embodiments with more than two filaments, a centroid
of a polygon formed by the distal ends of the filaments was
discussed. Both the midpoints and the centroids may be considered
to be "average" points of the filaments for their particular
configurations. In such embodiments, the midpoint between filaments
in two-filament embodiments and the centroid of the polygon in
embodiments with more than two filaments may be offset from the
central longitudinal axis of the elongate member. For example, the
midpoint or centroid may be offset from the central longitudinal
axis by 1 mm or more. In embodiments, the polygon may lie in a
plane perpendicular to the central longitudinal axis.
[0147] As illustrated in, for example, FIGS. 2A, 2D, 3A, 3C, 3D,
3G-3I, 5, 7, 8, 9, and 10, the distal ends of the filaments when
fully deployed may be in a common plane. In some embodiments, the
common plane is perpendicular or transverse to the central
longitudinal axis. In some embodiments, the common plane is distal
to the point 301, 312.
[0148] As illustrated in, for example, FIGS. 2A, 2D, 3A, 3C, 3D,
3G-3I, 5, 7, and 10, the filaments of the needle may all be
deployed on a common side of a central plane of the needle (where
the central longitudinal axis is entirely within the central
plane). In certain such embodiments, the distal ends of the
filaments are all on a common side of the central plane. Such a
configuration may enable the needle to be used to create a lesion
that is offset from the tip of the needle to the same side of the
central plane as the deployed filament ends.
[0149] As illustrated, for example, in FIG. 2A, 2D, 3A, 3C, 3D,
3G-3I, and 10, the filaments when fully deployed may point in an at
least partially distal direction. In this regard, a vector
extending longitudinally from the distal end of a filament and
coinciding with a central axis of the portion of the filament out
of the tip 211 has at least some distal component. The fully
deployed filaments in the embodiments illustrated in FIGS. 2A, 2D,
3A, 3C, 3D, 3G-3I, and 10 all point in an at least partially distal
direction.
[0150] FIG. 9 illustrates an embodiment in which the filaments are
uniformly distributed about the circumference of the tip 201''''.
The needle of FIG. 9 includes three filaments 901a, 901b, 901c
distributed substantially equally about the circumference of the
tip 201'''', the angles 902a, 902b, 902c between the filaments
901a, 901b, 901c each being about 120.degree.. Such a needle may be
operable to produce a lesion that is generally centered along the
central longitudinal axis 223. However, the position of the
produced lesion longitudinally along the central longitudinal axis
223 may be determined by the configuration (e.g., length,
deployment angle, etc.) of the filaments. For example, relatively
longer filaments may be operable to produce lesions that are
positioned distal to lesions produced by configurations with
relatively shorter filaments. For another example, in an embodiment
in which the filament 901b is longer than the filaments 901a, 901c,
the needle may be operable to create a lesion that is offset from
the tip of the needle towards the filament 901b. For yet another
example, in an embodiment in which the filaments 901a, 901b are
longer than the filament 901c, the needle may be operable to create
a lesion that is offset from the tip of the needle towards the
filaments 901a, 901b.
[0151] Referring again to FIG. 7, if the filament 701 was distal to
the filaments 206a, 206b, the resultant lesion may be longer along
the central longitudinal axis 223 than lesions resulting from an
embodiment in which the filaments 206a, 206b, 701 are each
positioned along substantially the same plane perpendicular or
transverse to the central longitudinal axis 223. In another
variation, as deployed, two or more filaments may be at the same
radial position and at different axial positions. Such embodiments
may include multiple rows of filaments.
[0152] Referring again to FIGS. 5 and 6, if the lengths of the
deployed portions of the filaments 206a, 206b were increased, the
needle may be capable of producing lesions that are more distally
positioned than lesions created by the embodiment as shown in FIGS.
5 and 6. The effects of lengthening or shortening the deployed
length of the filaments may be similar to those discussed herein
with respect to partially deploying filaments.
[0153] In some embodiments, the needle includes filaments having
deployed portions with different lengths. In certain embodiments in
which all of the filaments are deployed and/or retracted by a
common actuator and/or are part of the same wire, variations in
filament lengths may be achieved by varying the overall length of
the filaments. For example, the distal end of a shorter filament
may be retracted further into the tip or elongate member than the
distal end of a longer filament. The effects of lengthening or
shortening the length of the deployed portions of the filaments may
be similar to those discussed herein with respect to variations in
the axial positioning of filaments emergence from the tip of the
needle and/or with respect to partially deploying filaments.
[0154] The angle at which a filament exits a tip (e.g., the angle
601 of FIG. 6) may be varied to achieve particular lesion sizes,
positions, and/or shapes. For example, if the angle 601 in FIG. 6
was about 60.degree., the needle may be operable to produce a
lesion that has a larger maximum cross-sectional dimension in a
plane perpendicular to the central longitudinal axis 223 than if
the angle 601 was about 30.degree., for example because the
filaments can emanate RF energy at a distance further away from the
central longitudinal axis. In some embodiments, the filaments can
be deployed at different angles 601 relative to the central
longitudinal axis 223.
[0155] Referring again to FIG. 10, the deployed portions of the
filaments 1001a, 1001b may be curved. As described herein, the term
"curved" may mean a continuous curve, a curve in combination with a
straight section, a plurality of curves in different directions,
combinations thereof, and the like. Such curvatures may be
achieved, for example, by filaments 1001a, 1001b comprising shape
memory material (e.g., Nitinol) or spring material. When the
filaments 1001a, 1001b are retracted, the shape of the tip 201
and/or the elongate member 203 may cause the filaments 1001a, 1001b
to be in constrained straightened configurations. As the filaments
1001a, 1001b are advanced toward the fully deployed position, they
become unconstrained and return to their curved shapes as shown in
FIG. 10. The deployed shape of the filaments 1001a, 1001b may be
predetermined, or the filaments 1001a, 1001b may comprise (e.g., be
made from) a material that may be shaped by a user prior to
insertion. The filaments of other embodiments described herein
(e.g., FIGS. 3A, 3C, 3D, and 3G-3I) may also be curved. In some
embodiments, one filament is curved and one filament is
straight.
[0156] The curved filaments 1001a, 1001b of FIG. 10 are positioned
in planes that include the central longitudinal axis 223. In other
embodiments, the filaments 1001a, 1001b may be curved in other
directions, such as in a corkscrew arrangement. This may be
beneficial to assist the filaments in remaining anchored to the
tissue during delivery of RF energy. The curved filaments 1001a,
1001b of FIG. 10 may be operable to produce a lesion that is
flatter in a plane perpendicular to the central longitudinal axis
223 than, for example, the straight filaments 206a, 206b of FIG.
6.
[0157] In the embodiment illustrated in FIGS. 2A and 2B, the
filaments 206a, 206b are illustrated as running the entire length
of the elongate member 203 from the filament hub 221 to the tip
201. In some embodiments, a single member may run along at least
part of the elongate member 203 and the filaments 206a, 206b may be
interconnected to the single member at a point proximal to the tip
201.
[0158] The illustrated embodiments show all of the filaments of a
given embodiment as commonly deployed or retracted. In some
embodiments, one or more filaments may be individually deployed
and/or retracted. In some embodiments, a plurality of filaments may
exit from the tip at a common location and form a fan-like
arrangement as they are deployed.
[0159] Deployment of filaments discussed herein has been described
as movement of the filaments relative to a stationary tip. In some
embodiments, the filaments may be deployed by pulling the tip back
relative to the filaments (e.g., movement of the tip relative to
stationary filaments). Movement of the tip rather than the
filaments may be advantageous, for example, in embodiments in which
the needle is initially advanced until in contact with bone to
ensure proper positioning relative to target tissue, and then the
tip may be retracted, leaving the filaments (e.g., curved shape
memory filaments) in a precise, known position. In some
embodiments, the filaments may be deployed by advancing the
filaments and retracting the tip.
[0160] Referring again to FIGS. 2A and 2B, the hub 204 may be
fixedly attached to the elongate member 203. The hub 204 may be the
primary portion of the needle 103 gripped by the user during
insertion and manipulation of the needle 103. The hub 204 may
include an asymmetric feature, such as an indicator 225, that is in
a known orientation relative to the asymmetry of the tip 201. In
this regard, the indicator 225 may be used to communicate to the
user the orientation of the tip 201 within a patient. For example,
in the embodiment illustrated in FIG. 2A, the indicator 225 is
fixed at an orientation circumferentially opposite to the filament
slots 304a, 304b. Internally, the hub 204 may include a cavity 213
sized to house a longitudinal protrusion 218 of the actuator 216.
The hub 204 may include a hole through which a projection 215 may
project into the interior of the cavity 213 to control the motion
of the actuator 216 relative to the hub 204 and to secure the
actuator 216 to the hub 204. The hub 204 may comprise (e.g., be
made from) any appropriate material (e.g., a thermoset plastic,
Makrolon.RTM. 2548, available from Bayer).
[0161] The actuator 216 may be used to control the motion to deploy
and/or retract the filaments 206a, 206b. The actuator 216 is
operable to move relative to the hub 204, the elongate member 203,
and the tip 201 (e.g., parallel to the central longitudinal axis
223). The actuator 216 includes the longitudinal protrusion 218
extending into the cavity 213 of the hub 204. The outer surface of
the longitudinal protrusion 218 includes a helical track 219 sized
to accommodate the projection 215. In this regard, as the actuator
is rotated relative to the hub 204 (e.g., by a user to deploy the
filaments 206a, 206b), the helical track 219 and the projection 215
combine to cause the actuator 216 to move longitudinally (e.g.,
parallel to the central longitudinal axis 223). The actuator 216
comprises an interface portion 217 that may be gripped by a user
when rotating the actuator 216. The interface portion 217 may be
knurled or otherwise textured to enhance the user's ability to
rotate the actuator 216. The hub 204 may also include a textured or
shaped feature (e.g., the indicator 225) configured to enhance the
user's ability to rotate the actuator 216 relative to the hub 204.
The longitudinal protrusion 218 of the actuator 216 may include an
inner cavity 226 sized to accept a filament hub 221 and to allow
the filament hub 221 to rotate freely relative to the actuator 216.
In this regard, the linear motion of the actuator 216 may be
transmitted to the filament hub 221 while the rotational motion of
the actuator 216 may not be transmitted to the filament hub 221
[0162] The actuator 216 may include a Luer fitting 220 or any other
appropriate fitting type on a proximal end thereof. The Luer
fitting 220 may be in fluid communication with the lumen 222 and
provide a connection such that fluid may be delivered into the
lumen 222 and to the fluid port 210 of the tip 201, 211. The Luer
fitting 220 may also be configured to allow for the insertion of
the RF probe 401 into the lumen 222. The actuator 216 may comprise
any appropriate material (e.g., Pro-fax 6523 polypropylene
homopolymer, available from LyondellBasell Industries).
[0163] The filaments 206a, 206b may be fixedly interconnected to
the filament hub 221. In this regard, the longitudinal movement of
the filament hub 221 due to the actuator 216 may be communicated to
the filaments 206a, 206b to deploy and retract the filaments 206a,
206b upon rotation of the actuator 216. The filament hub 221 may
comprise any appropriate material (e.g., Pro-fax 6523 polypropylene
homopolymer, available from LyondellBasell Industries).
[0164] The user can deploy or retract the filaments 206a, 206b by
twisting or rotating the actuator 216. For example, as illustrated,
a counterclockwise (as seen from the viewpoint of FIG. 5) rotation
of the actuator 216 relative to the hub 204 will result in the
deployment (extension) of the filaments 206a, 206b, while a
clockwise rotation of the actuator 216 relative to the hub 204 will
result in the retraction of the filaments 206a, 206b.
[0165] The filaments 206a, 206b may be partially deployed or
retracted by partially rotating the actuator 216 relative to the
hub 204. The actuator 216 and/or the hub 204 may include markings
to indicate the position of the filaments 206a, 206b (e.g., the
depth or extent of deployment). The actuator 216 and/or the hub 204
may include detents to provide audible and/or tactile feedback of
the position of the filaments 206a, 206b.
[0166] In some embodiments, the filaments may be deployed at the
user's discretion to a deployed position proximal to, at, or distal
to a plane perpendicular or transverse to the central longitudinal
axis 223 at the point 301, 312. For example, in some embodiments,
full (e.g., 3/3) rotation of the actuator 216 may deploy the
filaments in a fully deployed position that is distal to a plane
perpendicular or transverse to the central longitudinal axis 223 at
the point 301, 312, partial (e.g., 2/3) rotation of the actuator
216 may deploy the filaments in a partially deployed position that
is at a plane perpendicular or transverse to the central
longitudinal axis 223 at the point 301, 312, and partial (e.g.,
1/3) rotation of the actuator 216 may deploy the filaments in a
partially deployed position that is proximal to a plane
perpendicular or transverse to the central longitudinal axis 223 at
the point 301, 312. The actuator 216 and/or the hub 204 may include
features such as stops or detents to provide audible and/or tactile
feedback regarding the extent of deployment (e.g., at 0/3, 1/3,
2/3, and 3/3) and/or the position of the filaments 206a, 206b
(e.g., fully retracted, 1/3 deployed, 2/3 deployed, and fully
deployed). Other fractions are also possible, including fractions
at uneven intervals (e.g., a combination of 1/3, 1/2, and 4/5). In
certain embodiments, selectable controlled partial deployment
allows for controlled adaptation of the lesion to any particular
shape and/or conformance of the filaments to a specific anatomy
(e.g., boney anatomy).
[0167] FIGS. 17A-17E illustrate components of the mechanism at the
proximal end 205 of the needle 103 of FIG. 2D. The mechanism may
also be used, for example, with the needle 103 of FIG. 2A and other
needles described herein. The components described with respect to
FIGS. 17A-17E may include features described herein with respect to
FIGS. 2B and 2C, and the components described herein, for example
with respect to FIGS. 2B and 2C may include features described
herein with respect to FIGS. 17A-17E. Combinations of components
are also possible.
[0168] FIG. 17A is an exploded view of components of the deployment
mechanism of FIG. 2D. The mechanism comprises an advancing hub or
slide member 1710, a spin collar or actuator 1720, and a main hub
1730. FIG. 17B is a cross-sectional view of the advancing hub 1710,
the spin collar 1720, and the main hub 1730 assembled together, as
well as half of the wire 206 illustrated in FIG. 2E. The advancing
hub 1710 includes a stem or longitudinal protrusion 1712. The spin
collar 1720 includes a lumen 1721 extending from the proximal end
to the distal end. The main hub 1730 includes a lumen 1731
extending from the proximal end to the distal end. When assembled,
the stem 1712 of the advancing hub 1710 is in the lumen 1721 of the
spin collar 1720 and in the lumen 1731 of the main hub 1730. The
advancing hub 1710 may include an annular protrusion 1714 that may
interact with an annular protrusion of the spin collar 1720 (e.g.,
the annular protrusion 1714 having a larger diameter than the
annular protrusion 1724) to inhibit the stem 1712 from exiting the
proximal end of the lumen 1721. In some embodiments, the annular
protrusions 1714, 1724 include tapered surfaces that may interact
to allow insertion of the stem 1712 and the annular protrusion 1714
into the lumen 1721 and perpendicular surfaces to inhibit the
annular protrusion 1714 and the stem 1712 from exiting the proximal
end of the lumen 1721. The main hub 1730 includes a stem or
longitudinal protrusion 1734. When assembled, the stem 1734 of the
main hub 1730 is in the lumen 1721 of the spin collar 1720. Other
interactions between the advancing hub 1710, the spin collar 1720,
and the main hub 1730 are described herein, for example with
respect to FIGS. 17C-17E.
[0169] FIG. 17C is a perspective view of an example embodiment of
the advancing hub 1710 and the wire 206 of FIG. 2E. The stem 1712
of the advancing hub 1710 comprises a U-shaped recess 1713
configured to interact with the bent proximal portion of the wire
206. Other shapes of the recess 1713 are also possible (e.g.,
V-shaped). The recess 1713 may complement the shape of the proximal
end of the wire 206. In some embodiments, the width of the recess
1713 is slightly smaller (e.g., about 0.001 inches (approx. about
0.025 mm) smaller) than the diameter of the wire 206 such that
after being press-fit, the wire 206 is fixedly interconnected to
the advancing hub 1710.
[0170] In some embodiments, the stem 1712 is shaped as illustrated
in FIG. 17C, including a perpendicular or transverse cross-section
that includes flat surfaces (e.g., the surface comprising the top
of the recess 1713) and arcuate surfaces, for example an ellipse
with squared ends. The lumen 1731 of the main hub 1730 may comprise
complementary surfaces, for example in a wider proximal portion,
such that when the stem 1712 is in the lumen 1731, the advancing
hub 1710 is in a fixed rotational position relative to the main hub
1710. Other shapes and rotational fixation configurations are also
possible.
[0171] The proximal end of the advancing hub 1710 comprises a
fitting 220 (e.g., a Luer fitting or any other appropriate
fitting). When assembled, the fitting 220 is proximal to the spin
collar 1720. The advancing hub 1710 comprises a lumen 1711
extending from the proximal end to the distal end. A fluid delivery
device such as a syringe may be attached to the fitting 220 to
deliver fluid through the lumen 1711 and then through the lumen
1731 of the main hub, the lumen 308 of the elongate member 203, the
lumen 306c of the tip 211, and out the fluid port 210 of the tip
211. The RF probe 401 may be inserted into the lumen 1711, then
into the lumen 1731 of the main hub, then into the lumen 308 of the
elongate member 203, then into the lumen 306c of the tip 211. The
RF probe 401 may include a fitting configured to interact with the
fitting 220. The lumen 1711 may include a wide diameter portion in
the area of the fitting 220 and a narrow diameter portion in the
area of the stem 1712, and a tapered surface 1715 transitioning
from the wide diameter portion to the narrow diameter portion. The
tapered surface 1715 may help direct fluid and/or an RF probe 401
into the narrow diameter portion. In some embodiments, the narrow
diameter portion of the lumen 1711 has a diameter between about
0.005 inches and about 0.05 inches (approx. between about 0.13 mm
and about 1.3 mm), between about 0.01 inches and about 0.03 inches
(approx. between about 0.25 mm and about 0.76 mm), between about
0.015 inches and about 0.025 inches (approx. between about 0.38 mm
and about 0.64 mm) (e.g., about 0.02 inches (approx. about 0.5
mm)), combinations thereof, and the like. In some embodiments, the
narrow diameter portion of the lumen 1711 has a diameter that is no
larger than the diameter of any other lumen of the needle 103 such
that fluid pressure will default to the distal end of the needle
103. For example, the narrow diameter portion of the lumen 1711 may
have a diameter of about 0.02 inches (approx. about 0.5 mm), the
narrow diameter portion of the lumen 1731 may have a diameter of
about 0.05 inches (approx. about 1.3 mm), the lumen 308 of the
elongate member 203 may have a diameter of about 0.05 inches
(approx. about 1.3 mm), and the lumen 306c may have a width of
about 0.02 inches (approx. about 0.5 mm). In some embodiments, the
lumen 306c may be slightly smaller than the narrow diameter portion
of the lumen 1711 and have the same effect, for example due to
small losses of fluid through the lumens 306a, 306b and out the
filament ports 304a, 304b, which may be acceptable because
anesthesia and dye, for example, may permeate through fluid and
proximate to the filament ports 304a, 304b even if substantially
only dispensed from the fluid port 210. In some embodiments, the
advancing hub 1710 comprises a polymer (e.g., Pro-fax 6523
polypropylene homopolymer, available from LyondellBasell
Industries).
[0172] FIG. 17D is a cross-sectional view of an example embodiment
of a spin collar 1720. The cross-section is along the same line as
in FIG. 17B, but further features are visible because not blocked
by the advancing hub 1710 or the main hub 1730. As illustrated in
FIG. 17B, the lumen 1721 is configured to at least partially
contain the stem 1712 and the stem 1734, and not to contact fluid
or an RF probe 401. The lumen 1721 comprises a helical track 1722
sized to interact with a corresponding helical thread 1735 (FIG.
17A) on the stem 1734 of the main hub 1730. As the spin collar 1720
is rotated relative to the main hub 1730 (e.g., by a user
stabilizing the needle and gripping the main hub 1730 with the
non-dominant hand and manipulating the spin collar 1720 with the
dominant hand), for example, to deploy the filaments 206a, 206b,
the helical track 1722 and the helical thread 1735 interact to
cause the spin collar 1720 and the advancing hub 1710 to move
longitudinally parallel to the central longitudinal axis 223. In
this regard, a linear motion of the advancing hub 1710 relative to
the main hub 1730 may be created while the rotational motion of the
spin collar 1720 may not be transmitted to the advancing hub 1710
and the main hub 1730. In some embodiments, between about 1.25
turns and about 1.5 turns of the spin collar 1720 fully deploys the
filaments 206a, 206b. In some embodiments, between about 0.75 turns
and about 1.25 turns (e.g., one 360.degree. rotation) of the spin
collar 1720 fully deploys the filaments 206a, 206b. The
configuration of the helical track 1722 and the helical thread 1735
may be adjusted to provide varying levels of filament deployment
with varying levels of rotation of the spin collar 1720. An outer
surface of the spin collar 1720 may be textured or include features
1723 to assist the user in gripping and twisting or rotating the
spin collar 1720 relative to the main hub 1730. In some
embodiments, the spin collar comprises the helical thread 1735 and
the main hub 1730 comprises the helical track 1722. In some
embodiments, the spin collar 1720 comprises a polymer (e.g.,
Pro-fax 6523 polypropylene homopolymer, available from
LyondellBasell Industries).
[0173] FIG. 17E is a cross-sectional view of an example embodiment
of the main hub 1730, taken along the line 17E-17E of FIG. 17B, in
exploded view with an example embodiment of an elongate member 203.
The proximal end of the elongate member 203, to the right in FIG.
17E, includes a partial circumferential portion 1736. The distal
end lumen 1731 of the main hub 1730 includes a complementary
partial circumferential portion 1737. The partial circumferential
portions 1736, 1737 can cause the elongate member 203 to be in a
fixed and known rotational orientation with the main hub 1730, for
example after assembly because the relative position of the
indicator 1733 and the partial circumferential portion 1737 is
known. For example, the distal end of the elongate member 203, to
the left in FIG. 17E, includes the filament ports 304a, 304b on the
same side as the partial circumferential portion 1736. Other
partial circumferential portions and other complementary shapes are
also possible. For example, the partial circumferential portions
may comprise interlocking teeth. In some embodiments, the thickness
of the partial circumferential portion 1737 is substantially the
same as the thickness of the walls of the elongate member 1736 to
provide a smooth transition between the lumen 1731 and the lumen
308. In some embodiments, the main hub 1730 comprises clear
polycarbonate (e.g., thermoset plastic such as Makrolon.RTM. 2548,
available from Bayer). In some embodiments, the elongate member
comprises a hypotube (e.g., comprising 300 Series Stainless Steel)
with features such as the filament ports 304a, 304b and the partial
circumferential portion 1736 cut out (e.g., by laser, mechanical,
chemical, or other cutting methods).
[0174] Other types of mechanisms may be used to control deployment
and retraction of the filaments. For example, in some embodiments,
the mechanism includes a spring configured to bias the filaments
206a, 206b toward a predetermined position (e.g., fully deployed,
fully retracted), analogous to a spring loaded mechanism used in
retractable ballpoint pens. For another example, the mechanism may
include a roller wheel, for example incorporated into the hub 204,
that would advance or retract the filaments 206a, 206b upon
rotation, for example with a user's thumb. For yet another example,
the hub 204 and the actuator 216 may interact via complimentary
threaded features. As the actuator 216 is threaded into the hub
204, the filaments 206a, 206b would advance, and as the actuator
216 is threaded out of the hub 204, the filaments 206a, 206b would
retract. For still another example, a Touhy-Borst type mechanism
could be incorporated to control the deployment and retraction of
the filaments 206a, 206b. Any other appropriate mechanism for
controlling linear motion of the filaments 206a, 206b may be
incorporated into the needle 103. Any of the mechanisms described
herein may be used for controlling deployment and retraction of the
filaments of any of the embodiments described herein. For example,
the mechanisms illustrated in FIGS. 2A-2D and 17A-17E may be used
to deploy and retract the filaments in FIGS. 3A, 3C, 3D, 3G-3I, and
5-10.
[0175] FIG. 2C is a partial cut away and partial cross-sectional
view of a portion of an alternate embodiment of a mechanism 230
comprising a hub 231 and actuator 232 that may be part of a needle
103 used in an RF neurotomy procedure. The hub 231 may be fixedly
attached to the elongate member 203. The hub 231 may be the primary
portion of the needle 103 gripped by the user during insertion and
manipulation of the needle 103. The hub 231 may include an
asymmetric feature, such as an indicator 233, that is in an known
orientation relative to the asymmetry of the tip 201. In this
regard, the indicator 233 may be used to communicate to the user
the orientation of the tip 201 within a patient. Internally, the
hub 231 may include a cavity 234 sized to house a longitudinal
protrusion 235 of a slide member 236. The longitudinal protrusion
235 may include a keyway or key slot 237 that may run along a
longitudinal direction of the longitudinal protrusion 235. The
internal surface of the hub 231 through which the longitudinal
protrusion 235 moves may include a mating key (not shown)
configured to fit and slide in the key slot 237. Together, the key
slot 237 and mating key of the hub 231 may limit the slide member
236 to a linear motion parallel to the central longitudinal axis
223.
[0176] The filaments 206a, 206b may be fixedly connected to the
longitudinal protrusion 235 of the slide member 236 for
longitudinal movement therewith. In this regard, distal movement
(e.g., movement to the right as shown in FIG. 2C) of the
longitudinal protrusion 235 relative to the hub 231 may cause
extension of the filaments 206a, 206b relative to the hub 231, the
elongate member 203, and the tip 201. For example, distal movement
of the longitudinal protrusion 235 may move the filaments 206a,
206b from a retracted position to a deployed position. For another
example, proximal movement (e.g., movement to the left as shown in
FIG. 2C) of the longitudinal protrusion 235 relative to the hub 231
may result in retraction of the filaments 206a, 206b relative to
the hub 231, the elongate member 203, and the tip 201.
[0177] The hub 231 may be made from any appropriate material (e.g.,
a thermoset plastic, Makrolon.RTM. 2548, available from Bayer). The
hub 231 may be at least partially transparent such that the
position of the longitudinal protrusion 235 and/or other components
of the hub 231 may be observable by a user. The hub 231 may further
include demarcations (e.g., molded or printed marks) such that the
amount of extension of the filaments 206a, 206b may be determined
from the position of the longitudinal protrusion 235 and/or other
components relative to the demarcations.
[0178] An actuator 232 may be used to control the motion to deploy
and/or retract the filaments 206a, 206b fixedly connected to the
longitudinal protrusion 235. The actuator 232 may be generally
tubular such that it fits around a longitudinal hub projection 238
projecting from the proximal end of the hub 231. At least a portion
of the cavity 234 may be in the longitudinal hub projection 238.
The actuator 232 may also include an annular feature 239 configured
to fit in an annular slot 240 in the slide member 236. The annular
feature 239 may be sized relative to the annular slot 240 such that
the actuator 232 may rotate relative to the slide member 236 about
the central longitudinal axis 223 or an axis parallel thereto while
the position of the actuator 232 relative to the slide member 236
along the central longitudinal axis 223 remains fixed. In this
regard, the actuator 232 and the slide member 236 may be configured
to move in tandem relation along the central longitudinal axis 223.
The annular feature 239 and annular slot 240 may be configured such
that, during assembly, the actuator 232 may be pressed onto the
slide member 236 and the annular feature 239 may snap into the
annular slot 240.
[0179] The inner surface of the actuator 232 may include a helical
track 241 sized to accommodate a corresponding mating helical
thread 242 on the longitudinal hub projection 238. In this regard,
as the actuator 232 is rotated relative to the slide member 236 and
the hub 231 (e.g., by a user to deploy the filaments 206a, 206b),
the helical track 241 and the helical thread 242 interact to cause
the actuator 232 and the slide member 236 to move longitudinally
along the central longitudinal axis 223. In this regard, a linear
motion of the slide member 236 relative to the hub 231 may be
created while the rotational motion of the actuator 232 may not be
transmitted to the slide member 236 and the hub 231. An outer
surface of the actuator 232 may be textured or include features to
assist the user in gripping and twisting or rotating the actuator
232 relative to the hub 231. In some embodiments, the longitudinal
hub projection 238 comprises the helical track 241 and the inner
surface of the actuator 232 comprises the helical thread 242.
[0180] The proximal end of the slide member 236 may include a Luer
fitting 243 or any other appropriate fitting type. The Luer fitting
243 may be in fluid communication with a lumen passing through the
slide member 236 and may provide a connection such that fluid may
be delivered through the Luer fitting 243 and into the lumen of the
slide member 236. In turn, the lumen of the slide member 236 may be
in fluid communication with the cavity 234 of the hub 231, which
may in turn be in fluid communication with a lumen in the elongate
member 223 (e.g., the lumen 222). The lumen in the elongate member
223 may be in fluid communication with the tip 201 (e.g., the fluid
port 210). In this regard, fluid may flow into the Luer fitting
243, into and through the lumen in the slide member 236, into and
through the cavity 234 of the hub 231, into and through the
elongate member 223, and out from fluid portion 210 of the tip 201.
The Luer fitting 243, the lumen in the slide member 236, the cavity
234 of the hub 231, and the lumen of the elongate member 223 may
all also be configured to allow for the insertion of the RF probe
401 therethrough. The protrusion 235 and the cavity 234 of the
longitudinal hub projection 238 may be sized and/or configured to
form a fluid seal therebetween, allowing fluid delivered under
pressure through the Luer fitting 220 to flow through the cavity
238 and into the elongate member 203 substantially without leaking
past the interface between the protrusion 235 and the cavity 234 of
the longitudinal hub projection 238.
[0181] As described herein, the filaments 206a, 206b may be fixedly
interconnected to the slide member 236. Axial movement of the slide
member 236 due to the actuator 232 may be thereby communicated to
the filaments 206a, 206b to deploy and retract the filaments 206a,
206b upon rotation of the actuator 232. The slide member 236 may be
made from any appropriate material (e.g., Pro-fax 6523
polypropylene homopolymer, available from LyondellBasell
Industries). The actuator 232 may be made from any appropriate
material (e.g., Pro-fax 6523 polypropylene homopolymer, available
from LyondellBasell Industries).
[0182] The user can deploy or retract the filaments 206a, 206b by
twisting or rotating the actuator 232. By partially rotating the
actuator 232 relative to the hub 231, the filaments 206a, 206b may
be partially deployed or retracted. The actuator 232 and/or hub 231
may include detents to provide audible and/or tactile feedback of
the position of the filaments 206a, 206b. The detents may be
configured such that audible and/or tactile feedback associated
with engagement of a detent coincides with a predetermined amount
of deployment or retraction of the filaments 206a, 206b, as
described herein. In this regard, such audible and/or tactile
feedback may be used in determining filament position.
[0183] In some embodiments, the needle 103 is a multipolar (e.g.,
bipolar) device in contrast to the monopolar devices described
herein. In certain such embodiments, the filaments are isolated
from each other and/or from the tip to enable bipolar operation
(e.g., the filaments having one polarity and the tip having a
second polarity, one filament having one polarity and one filament
and the tip having a second polarity, one filament having one
polarity and one filament having a second polarity, etc.). In
embodiments in which the needle 103 comprises more than two
filaments, elements may be included to allow for selection of the
polarity of the certain filaments to aid in lesion shape, size,
and/or position control. In some embodiments, the needle 103 may be
used in either a monopolar mode or in a bipolar mode as selected by
the user. For example, RF probes 401 may include shapes, insulating
features, etc. configured to produce monopolarity or
bipolarity.
[0184] The herein-described embodiments of needles may be used in
spinal RF neurotomy procedures, which will now be described. In
general, for an RF neurotomy procedure, the patient may lie face
down on a table so that the spine of the patient is accessible to
the user. At any appropriate time before, during, and/or after the
procedure, the user may use imaging equipment, such a fluoroscope,
to visualize the patient's anatomy and/or to visualize the
positioning of equipment (e.g., the needle relative to a target
volume).
[0185] The patient may be administered sedatives and/or intravenous
fluids as appropriate. The skin of the patient surrounding the
procedure location may be prepared and maintained using an
appropriate sterile technique. In embodiments in which the needle
is monopolar, a return electrode pad 104 may be attached to the
patient. A local anesthetic may be injected subcutaneously where
the needle will be inserted or along the approximate path of the
needle, for example through the needle itself or through a
different needle.
[0186] With the filaments in the retracted position, the needle may
be introduced into the patient and moved to a target position
relative to a target portion of a target nerve or to a target
position relative to a target volume in which the target nerve is
likely situated (all of which are generally referred to herein as
the target nerve or portion of the target nerve). The target nerve
may be an afferent nociceptive nerve such as, for example, a medial
branch nerve proximate a lumbar facet joint. Introduction of the
needle into the patient may include percutaneously using the tip of
the needle to pierce the skin of the patient. The moving of the
needle may include navigating toward the target position using
fluoroscopic guidance. Furthermore, the moving of the needle may
include advancing the needle to an intermediate position and then
repositioning the needle to the target position. For example, the
needle may be advanced until it contacts a bone or other structure
to achieve the intermediate position. This may be followed by
retracting the needle a predetermined distance to achieve the
target position. Such a procedure may be facilitated by the markers
224 or collar discussed herein.
[0187] During the moving of the needle or after the target position
has been achieved, the needle may be used to inject an anesthetic
and/or a dye proximate to the target nerve. The dye may increase
contrast in fluoroscopic images to assist in visualizing the
patient's anatomy, which may aid the user in guiding and/or
verifying the position of the needle.
[0188] The needle may be rotated about the central longitudinal
axis of the elongate member of the needle to achieve a desired
orientation relative to the target nerve. For example, the needle
may be rotated such that a lesion created with the needle with the
filaments deployed will be offset from the central longitudinal
axis toward the target nerve. Such rotation of the needle may be
performed prior to insertion of the needle into the patient and/or
after insertion into the patient. For example, the user may rotate
the needle prior to insertion such that the needle is generally in
the desired rotational orientation. Then, after achieving the
target position, the user may fine tune the rotational orientation
of the needle by rotating the needle to a more precise orientation.
As described herein, the hub or another portion of the needle
outside the patient's body may indicate the rotational orientation
of the needle.
[0189] Once the target position and desired rotational orientation
have been achieved, the next step may be to advance one or more
filaments of the needle relative to the tip of the needle. The
particular needle used for a procedure may have been selected to
enable the creation of a particular sized and shaped lesion at a
particular position relative to the needle. The particular needle
used may be of any appropriate configuration discussed herein
(e.g., any appropriate number of filaments, any appropriate
filament positioning, monopolar or bipolar, any appropriate
deployment and retraction mechanism, etc.).
[0190] In embodiments in which the needle is configured as
illustrated in FIGS. 5 and 6 (e.g., about 120.degree. apart), the
advancement of filaments may include advancing the filaments such
that when the filaments are in their respective deployed positions,
a midpoint between a distal end of the first filament and a distal
end of the second filament is offset from the central longitudinal
axis of the needle, and the filament endpoints are distal to the
tip of the needle. Such deployment may enable the needle to be used
to create a lesion that is offset from the tip of the needle toward
the midpoint between the deployed filament ends. The lesion created
may also be positioned at least partially distal to the tip of the
needle.
[0191] FIG. 11A is an illustration of an example set of isotherms
1010a-1010c that may be created with the needle 103 of FIG. 2A. As
illustrated by the set of isotherms 1010a-1010c, RF energy
emanating from the tip 201 and from the filaments 206a, 206b, may
produce a region of elevated temperature about the tip 201 and the
filaments 206a, 206b. The isotherms 1010a-1010c may be offset from
the central longitudinal axis 223 such that a centroid of the
isotherms as viewed in FIG. 11A is offset from the central
longitudinal axis 223 in the direction of the filaments 206a, 206b.
The centroid of the isotherms 1010a-1010c as viewed in FIG. 11A may
also be distal relative to the tip 201 and between the tip 201 and
the distal ends of the deployed filaments 206a, 206b. The isotherms
1010a-1010c may also be shaped such that, as viewed in FIG. 11A,
the isotherms 1010a-1010c have a maximum cross-sectional dimension
along the central longitudinal axis 223 that is greater than a
maximum cross dimension in the plane of FIG. 11A perpendicular to
the central longitudinal axis 223. As visible in the illustrated
orientation of FIG. 11B, the isotherms 1010a-1010c may have a
maximum cross-sectional dimension along the central longitudinal
axis 223 that is greater than a maximum cross-sectional dimension
perpendicular to the plane of FIG. 11A and perpendicular to the
central longitudinal axis 223.
[0192] The offset of the centroid of the isotherms 1010a-1010c from
the central longitudinal axis 223 may result in greater lesion
width in a plane perpendicular to the central longitudinal axis
223, as compared to a similarly-sized straight needle with no
filaments. The offset of the centroid of the isotherms 1010a-1010c
may also allow for projection of the centroid of a corresponding
lesion volume in a direction away from the central longitudinal
axis 223. By way of example, such offsets may advantageously enable
the execution of the example procedures described herein. Such
offsets may advantageously enable the creation of lesion volumes
distal (relative to the needle 103) to potentially interfering
structures (e.g., an ossified process). Such offsets may
advantageously enable the needle 103 to be inserted into a patient
at a more desirable angle (e.g., closer to perpendicular to the
surface of the patient such as within 30.degree. of perpendicular
to the surface of the patient), at a more desirable piercing
location, and/or through more desirable tissue than may be
attempted using a needle without offset lesion capabilities.
[0193] FIG. 11B is an illustration of an example lesion 1011 that
may be created with the needle 103 of FIG. 2A. In FIG. 11B, the
needle 103 has been placed perpendicular to a surface 1012. The
surface 1012 may, for example, be the surface of a bone, such as a
lumbar vertebra. As illustrated, the filaments 206a, 206b are
deployed such they are proximate to the surface 1012. In some
embodiments, contact with the surface 1012 might undesirably deform
the filaments 206a, 206b, but such contact may be avoided, for
example by the needle advancement and retraction procedures
described herein. The lesion 1011 has a width along the surface
1012 that is wider than would be created by the needle 103 if the
filaments 206a, 206b were not deployed. Such capabilities may, for
example, be advantageous where a target structure (e.g., a nerve)
is known to be positioned along the surface 1012, but its exact
position is unknown. In such a case, the needle 103 may be
positioned generally perpendicular to the surface 1012 to achieve
the illustrated lesion width along the surface 1012, whereas
achieve the same lesion width along the surface 1012 using a the
needle 103 without the filaments 206a, 206b deployed would require
either multiple repositioning steps or placement of the needle 103
generally parallel to the surface 1012.
[0194] FIG. 11C is an illustration of an example lesion 1022 that
may be created with a single-filament needle 1020. The
single-filament needle 1020 may be similar to the needle 103,
although the single-filament needle 1020 includes only a single
filament 1021. The filament 1021 may be configured similarly to the
filaments 206a, 206b. The single-filament needle 1020 with the
filament 1021 deployed may be operable to produce a lesion 1022
that is a flattened version (e.g., thinner in a direction
perpendicular to the central longitudinal axis 223, which is the
left to right direction as illustrated in FIG. 11C) of a lesion
that may be produced by the needle 103 with two filaments 206a,
206b deployed. The capability to produce such a lesion shape may be
beneficial when it is desirable to have a relatively large lesion
in a particular direction (e.g., to compensate for the variability
of location of a target nerve) and a relatively small lesion width
in another direction (e.g., to avoid a structure such as viscera or
a patient's skin). As described herein, certain embodiments of the
needle 103 may allow differential or selective deployment and/or
activation of the filaments 206a, 206b such that the needle 103 may
imitate the single-filament needle 1020.
[0195] In embodiments in which the needle is configured such that
all of the filaments of the needle are deployed on a common side of
a central plane of the needle (in which the central longitudinal
axis is entirely within the central plane), the advancement of
filaments may include advancing the filaments such that when the
filaments are in their respective deployed positions, the distal
ends of all of the filaments are on a common side of the central
plane. Such deployment may enable the needle to be used to create a
lesion that is offset from the tip of the needle to the same side
of the central plane as the deployed filament ends. The lesion
created may also be positioned at least partially distal to the tip
of the needle.
[0196] In embodiments in which the needle is configured as
illustrated in FIG. 7 or 8, the advancement of filaments may
include advancing the filaments such that when the filaments are in
their respective deployed positions, each filament distal end
defines a vertex of a polygon whose centroid is offset from a
central longitudinal axis of the needle. Such deployment may enable
the needle to be used to create a lesion that is offset from the
tip of the needle toward the centroid. The lesion created may also
be positioned at least partially distal to the tip of the
needle.
[0197] The advancement of the filaments may be achieved using any
of the mechanisms discussed herein. For example, in the embodiment
of FIG. 2A, rotating the actuator 216 relative to the hub 204 may
cause the filaments to advance to the deployed position. The
advancement of the filaments may be performed such that each of the
plurality of filaments passes through a surface of the needle that
is parallel to the central longitudinal axis of the needle. In some
embodiments, the filaments of the needle may be advanced to a
position that is an intermediate position between the retracted
position and the fully deployed position. The degree of deployment
may be based on the desired lesion size and/or the accuracy of the
placement of needle. For example, the same needle may be used in
two different procedures where the variability of the location of a
target nerve is greater in the first procedure than it is in the
second procedure. In such situation, the greater deployment of the
filaments may be used in the first procedure, whereas in the second
procedure, a smaller degree of deployment may be used since a
smaller lesion may suffice to ensure that the target nerve has been
ablated. For another example, after placement of the needle during
a procedure, the position of the needle may be determined to be
slightly offset from a target position. In such a case, the
filaments may be deployed to a greater degree than would have been
required if the needle were placed exactly on target. In such a
case, the greater degree of deployment may be used to compensate
for the needle positioning inaccuracy. In such a case, needle
repositioning and possible associated trauma may be avoided.
[0198] During and/or after advancing the filaments to the deployed
position, their positions may be confirmed using an imaging system
(e.g., using a fluoroscope). Proper filament positioning may also
be verified by using the needle to stimulate the target nerve. For
example, an electrical signal (e.g., up to about 2 volts applied at
about 2 Hz) may be applied to the needle and the user may observe
any related patient movement (e.g., muscle fasciculation in the
territory supplied by the nerve). For another example, an
electrical signal (e.g., up to about 1 volt applied at about 50 Hz)
may be applied to the needle and the patient may indicate if they
feel any associated sensations and their locations to assist in
verifying correct needle positioning. Such stimulation
(user-observed and/or patient reported) may be used to stimulate a
targeted nerve to determine if the deployed position is adequate to
achieve denervation of the targeted nerve. In this regard, it is
desirable for the stimulation to affect the targeted nerve. Upon
determination that the target nerve is stimulated, increased energy
may be applied to ablate a volume comprising the target nerve.
[0199] Such stimulation may also be used to attempt to stimulate a
nerve that is not targeted for denervation (e.g., a nerve where no
denervation is desired) to determine the position of the needle
relative to such a non-targeted nerve. In this regard, if the
stimulation signal does not stimulate the non-targeted nerve, the
user may determine that the position of the needle relative to the
non-targeted nerve is such that the application of ablation energy
to the needle will not result in significant damage to (e.g.,
ablation of) the non-targeted nerve. If the stimulation stimulates
the non-targeted nerve (e.g., as determined by user observation
and/or patient reporting), the needle may be repositioned to avoid
damaging the non-targeted nerve. In this regard, it is desirable
for the stimulation not to affect the non-targeted nerve.
[0200] After correct needle positioning has been verified (e.g., by
imaging and/or stimulation), an anesthetic may be injected through
the needle, for example out of at least one of the fluid port 210,
320, the filament ports 304a, 304b, 318a, 318b, the lumen 306c,
etc.
[0201] After the filaments have been advanced to the desired
position, the next step may be to apply RF energy to the needle
using the interconnected RF generator. In embodiments that use a
separate RF probe to deliver RF energy, the RF probe may be
inserted into a lumen of the needle prior to application of the RF
energy. When using such a configuration, the application of RF
energy may include applying RF energy to the RF probe and
conducting the RF energy away from the probe by the tip and/or
filaments.
[0202] The resultant RF energy emanating from the tip and/or the
filaments may generate heat that ablates the target nerve. Such
ablation may be achieved by creating a lesion volume that includes
the target nerve. It is desired that the target nerve be completely
ablated to prevent incomplete neurotomy which may result in
dysesthesia and/or patient discomfort. For example, a lesion with a
maximum cross-sectional dimension between about 8 mm and about 10
mm may be created. Larger or smaller lesions may be created by
varying filament characteristics (e.g., filament advancement
distance) and/or RF energy levels. The created lesion may be offset
from the central longitudinal axis of the needle. The center of the
lesion may be distal to the tip of the needle. Of note, since the
RF energy is emanating from the tip and filaments, a particularly
sized lesion may be created with a lower peak temperature (the
maximum temperature experienced in the patient) than would be
possible if a needle without filaments or without deployed
filaments were to be used to create the same-sized lesion. For
example, a particular lesion may be achieved with the needle with
deployed filaments where the peak temperature is between about
55.degree. C. and about 60.degree. C. or less than about 70.degree.
C., whereas creation of the same lesion using a needle without
filaments or without deployed filaments could require a peak
temperature of about 80.degree. C. Such lower temperature lesions
achievable by a needle with deployed filaments may result in
greater patient safety and/or procedure tolerance.
[0203] Before, during, and/or after the application of RF energy, a
temperature sensor (e.g., thermocouple) at or near the tip of the
needle may be used to monitor the temperature at or near the tip.
Such readings may be used as control signals (e.g., a feedback
loop) to control the application of RF energy to the needle. For
example, control signals and/or temperature data may be used for
closed-loop control of the needle 103 by automatic adjustment of a
parameter (e.g., frequency, wattage, and/or application duration of
the RF energy, and/or filament deployment length, needle position,
etc.) upon detection of a temperature. Feedback loops involving the
user are also possible. If it is desired to ablate additional
target nerves or to ablate an additional volume to ensure ablation
of the original target nerve, the spinal RF neurotomy procedure may
continue. In some embodiments, the distal end 402 of the RF probe
401 is a dual-purpose wire that can deliver RF energy to the tip
and/or the filaments and that can act as a thermocouple (e.g.,
having thermosensing properties).
[0204] In embodiments in which the needle is configured to create
lesions offset from the central longitudinal axis, and an
additional target nerve or target volume is within a volume that
may be ablated using the needle in its current position but in a
different rotational orientation, the procedure may continue as
follows. First, after the initial RF energy application, the
filaments may be retracted into the needle. Once retracted, the
needle may be rotated, and the filaments redeployed. The
redeployment may have the same characteristics (e.g., length of the
deployed portions of the filaments) as the original deployment or
different characteristics. Next, the reoriented needle may be used
to at least partially ablate the additional target nerve or target
volume. Such retargeting of ablation volumes without repositioning
(e.g., without withdrawing the needle from the patient and
reinserting), may result in reduced patient trauma as compared to
known spinal RF neurotomy procedures, which may require removal and
reinsertion of a needle to achieve lesioning of the second target
volume. Moreover, such retargeting of ablation volumes without
repositioning (e.g., with only rotation of the needle, without
additional tissue piercing) may result in the ability to create
uniquely shaped lesions from a single insertion position. Such
shaped lesions may include, for example, lesions that are in the
shape of two or more intersecting spheres or oblong spheroids. The
steps of retracting the filaments, rotating the needle, redeploying
the filaments, and applying RF energy may be repeated a plurality
of times. In some embodiments, an second ablation volume may be
defined without rotating the needle, but by different deployment
characteristics (e.g., lengths, RF energy parameters, etc.) of the
filaments.
[0205] In embodiments in which the additional target nerve or
target volume is not within a volume that may be ablated by
rotating the needle, the needle may be repositioned. Such
repositioning may include partially or fully removing the needle
from the patient and then repositioning the needle and repeating
the herein-described steps. In some embodiments, the second
ablation is performed using a different needle (e.g., a needle with
different properties (e.g., longer filaments)) than the original
needle.
[0206] When no additional ablation is desired, the filaments of the
needle may be retracted, and the needle may be removed from the
patient. After removal of the needle, a sterile bandage may be
placed over the needle insertion site or sites. The patient may
then be held for observation and recovery from the effects of any
sedative that may have been administered.
[0207] Examples of specific spinal RF neurotomy procedures will now
be described. Generally, steps unique to each procedure will be
discussed while steps common to any spinal RF neurotomy procedure
(e.g., site preparation such as infiltrating the skin and
subcutaneous tissues with 1.5% lidocaine to achieve skin
anesthesia, nicking the skin to facilitate needle insertion,
insertion monitoring with fluoroscopy, stimulation, etc., filament
deployment mechanics, needle removal, and the like) will not be
further discussed. Each of the procedures is described as being
performed with a needle comprising two filaments offset from the
central longitudinal axis, for example as described herein. It will
be appreciated that the variations in needle configuration
discussed herein may be used in these procedures. For example, to
increase the offset of the created lesion relative to the central
longitudinal axis, curved filaments (e.g., as illustrated in FIG.
10) and/or partially insulated filaments (e.g., as illustrated in
FIGS. 3H and 3I) may be used to create a lesion different
properties (e.g., greater offset from the central longitudinal
axis).
1. Lumbar RF Neurotomy of a Medial Branch Nerve Proximate a Lumbar
Facet Joint.
[0208] This process may include using a needle that enables the
creation of lesions that are offset from the central longitudinal
axis. The procedure will be described as being performed on the L5
vertebra 1101 of FIG. 12 and the needle 103 of FIG. 2A. It should
be understood that other embodiments of needles described herein
and/or other lumbar vertebra may be used in the described procedure
or variations thereof.
[0209] The lumbar RF neurotomy process may include positioning the
tip 201 of the needle 103 (e.g., using fluoroscopic navigation)
such that the tip 201 is in contact with, or proximate to, the
groove 1102 between the transverse process 1103 and the superior
articular process 1104 of the targeted lumbar vertebra 1101. Such
positioning is shown in FIG. 12. By contacting the lumbar vertebra
1101, a positive determination of the position of the needle 103
may be made. By way of example, such positioning may be performed
such that the needle 103 is within 30.degree. of being
perpendicular to the lumber vertebra 1101 at the point of contact
with the lumbar vertebra 1101, or at the point of the lumbar
vertebra 1101 closest to the tip 201 of the needle 103. Optionally,
from such a position, the needle 103 may be retracted a
predetermined amount (e.g., between about 3 mm and about 5 mm), for
example as measured by markers 224 on the needle 103, as determined
using the collar about the elongated member 203 discussed herein,
and/or by fluoroscopic navigation.
[0210] The process may include rotating the needle 103 such that
the midpoint 502 is oriented toward the superior articular process
1104 and a medial branch nerve 1105 that is positioned along a
lateral face 1106 of the superior articular process 1104. Next, the
filaments 206a, 206b may be advanced to the deployed position, as
shown in FIG. 12. The positions of the needle 103 and the deployed
filaments 206a, 206b may be verified using fluoroscopy and/or
patient stimulation (e.g., motor and/or sensory). The RF probe 401
may then be inserted into the lumen 222 such that RF energy
emanating from the probe 103 will be conducted by the tip 201 and
filaments 206a, 206b to the target medial branch nerve 1105 and
away from the intermediate branch of the posterior primary
ramus.
[0211] Next, RF energy may be applied to the RF probe 401. The RF
energy emanating from the needle 103 may be preferentially biased
toward the target medial branch nerve 1105. The lesion created by
such a procedure may, for example, have a maximum cross-sectional
dimension of between about 8 mm and about 10 mm, and may ablate a
corresponding portion of the medial branch nerve 1105, thus
denervating the facet joint.
[0212] In some embodiments, the needle may be operable to create a
generally symmetric lesion relative to its central longitudinal
axis (e.g., as illustrated in FIG. 9). In certain such embodiments,
the sequence of steps may include insert needle, deploy filaments,
and apply RF energy.
[0213] In some embodiments, the needle may be inserted to be along
the length of a portion of the nerve (as illustrated by needle 103'
outlined by broken lines). Such positioning may be similar to known
methods of RF neurotomy performed using needles without filaments.
After positioning the needle, the filaments may be deployed and a
lesion may be created. As noted herein, a needle with deployable
filaments that is capable of producing a lesion equivalent to that
of a needle without deployable filaments may be smaller in diameter
than the needle without deployable filaments. Although positioning
of the needle 103' may be similar to known processes, the process
utilizing the needle 103' with deployable filaments may cause less
trauma and be safer than procedures using a needle without
deployable filaments due to the smaller size of the needle with
deployable filaments. As discussed herein, the peak temperatures
capable of producing the desired lesion volume may be less when
using the needle 103' with deployable filaments as compared to a
needle without deployable filaments, further contributing to
patient safety. The filaments of the needle 103' may be partially
or fully deployed to achieve a desired lesion location, shape,
and/or size.
[0214] It is noted that the illustrated deployment of needle 103
with the filaments 206a, 206b deployed may be used to create a
lesion that approximates a lesion that would be created with the
needle without filaments that is placed in the position of needle
103' (e.g., parallel to the target nerve 1105). The placement of
needle 103 generally perpendicular to the surface of the L5
vertebra 1101 may be less difficult to achieve than the parallel
placement of the needle 103'.
2. Sacroiliac Joint (SIJ) RF Neurotomy of the Posterior Rami.
[0215] This process may include using a needle that enables the
creation of lesions which are offset from the central longitudinal
axis. The procedure will be described as being performed on the
posterior rami 1201 of the SIJ of FIG. 12 and using the needle 103
of FIG. 2A. It should be understood that other embodiments of
needles described herein and/or other portions of the SIJ may be
used in the described procedure or variations thereof.
[0216] As part of the SIJ RF neurotomy process, it may be desirable
to create a series of lesions in a series of lesion target volumes
1203a-1203h lateral to the sacral foramina 1211, 1212, 1213 of a
side of the sacrum 1200 to ablate posterior rami 1201 that are
responsible for relaying nociceptive signals from the SIJ. Since
the exact positions of the rami 1201 may not be known, ablating
such a series of target volumes 1203a-1203h may accommodate the
variations in rami 1201 positions. The series of target volumes
1203a-1203h may be in the form of one or more interconnected
individual target volumes, such as the target volumes 1203a, 1203b.
In some embodiments, the process further comprises forming a lesion
1208 between the L5 vertebra 1209 and the sacrum 1200 to ablate the
L5 dorsal ramus.
[0217] The SIJ RF neurotomy process may include positioning the tip
201 of the needle 103 (e.g., using fluoroscopic navigation) such
that it is in contact with, or proximate to, and in lateral
relation to the S1 posterior sacral foraminal aperture (PSFA) 1211
at a first point 1204 that is at the intersection of the two target
volumes 1203a, 1203b. Such positioning may be performed such that
the needle 103 is oriented within 30.degree. of being perpendicular
to the sacrum 1200 at the point of contact (or at the point of the
sacrum 1200 closest to the tip 201 of the needle 103). By
contacting the sacrum 1200, a positive determination of the
position of the needle 103 may be made. Optionally, from such a
position, the needle 103 may be retracted a predetermined amount
(e.g., between about 3 mm and about 5 mm) as measured, for example,
by markers 224 on the needle 103, as determined using the collar
about the elongated member 203 discussed herein, and/or by
fluoroscopic navigation. For example, a contralateral posterior
oblique view may be obtained to ascertain that the tip 201 has not
entered the spinal canal. For example, a fluoroscopic view may be
obtained looking down the length of the needle 103 to verify that
the needle 103 is properly offset from the S1 PSFA 1211 and/or a
fluoroscopic view may be obtained looking perpendicular to the
central longitudinal axis 223 to verify that the needle 103 is not
below the surface of the sacrum (e.g., in the S1 PSFA 1211). An
electrical signal may be applied to the needle 103 to stimulate
nerves proximate to the tip 201 to verify correct needle 103
placement.
[0218] The SIJ RF neurotomy process may include rotating the needle
103 such that the midpoint 502 is oriented toward the first target
volume 1203a in the direction of arrow 1205a. Next, the filaments
206a, 206b may be advanced to the deployed position. The position
of the needle 103 and the deployed filaments 206a, 206b may be
verified using fluoroscopy and/or stimulation (e.g., motor and/or
sensory). The RF probe 401 may be inserted into the lumen 222
before, during, and/or after filament deployment such that RF
energy emanating from the needle 103 will be conducted by the tip
201 and the filaments 206a, 206b to the first target volume 1203a.
Next, RF energy may be applied to the RF probe 401. The RF energy
emanating from the needle 103 may be preferentially biased toward
the first target volume 1203a. The lesion created by such an
application of RF energy may, for example, have a maximum
cross-sectional dimension of between about 8 mm and about 10 mm,
and may ablate a corresponding portion of the rami 1201.
[0219] Next, the filaments 206a, 206b may be retracted and the
needle 103 may be rotated approximately 180.degree. such that the
midpoint 502 is oriented toward the second target volume 1203b in
the direction of arrow 1205b Optionally, some lateral repositioning
of the needle may performed (e.g., without any needle pull back or
with a small amount of needle pull back and reinsertion). Next, the
filaments 206a, 206b may be advanced to the deployed position. The
position of the needle 103 and the deployed filaments 206a, 206b
may be verified using fluoroscopy and/or stimulation (e.g., motor
and/or sensory). The RF probe 401 may remain in the lumen 222
during the repositioning, or may be removed and then reinserted.
Next, RF energy may be applied to the RF probe 401 to create a
lesion corresponding to the second target volume 1203b.
[0220] In this regard, with a single insertion of the needle 103,
two interconnected lesions (which may also be considered to be a
single oblong lesion) may be created. Compared to methods in which
an RF probe must be repositioned prior to each application of RF
energy, the number of probe repositioning steps may be greatly
reduced, reducing patient trauma and procedure duration. In this
regard, a continuous region of lesioning may be achieved about the
S1 PSFA 1211 such that the lesion occupies a volume surrounding the
S1 PSFA 1211 from about the 2:30 clock position to about the 5:30
clock position (as viewed in FIG. 13). Such lesioning may help to
achieve denervation of the posterior rami proximate to the S1 PSFA
1211.
[0221] The herein procedure may be repeated as appropriate to
create lesions corresponding to the entire series of target volumes
1203a-1203h, thus denervating the SIJ. For example, a first
insertion may ablate the volumes 1203a, 1203b, a second insertion
may ablate the volumes 1203c, 1203d, a third insertion may ablate
the volumes 1203e, 1203f, and a fourth insertion may ablate the
volumes 1203g, 1203h. In this regard, a similar continuous region
of lesioning may be achieved about the S2 PSFA 1212 and a region of
lesioning from about the 12:00 clock position to about the 3:00
clock position (as viewed in FIG. 13) relative to the S3 PSFA may
be achieved about the S3 PSFA 1213. A lesion 1208 may also be
created at the base of the superior articular process of the L5
1209 dorsal ramus in the grove between the superior articular
process and the body of the sacrum. The needle 103 may be inserted
generally perpendicular to the plane of FIG. 13 to produce the
lesion 1208.
[0222] In some embodiments, three or more lesions may be created
with a needle in a single position. For example, a needle
positioned at a point 1206 proximate to three target volumes 1203c,
1203d, 1203e, may be operable to create lesions at each of the
three target volumes 1203c, 1203d, 1203e, thus further reducing the
number of needle repositionings.
[0223] In some embodiments, each individual lesion corresponding to
the series of target volumes 1203 may be created using a needle
with deployable filaments in which the needle is repositioned prior
to each application of RF energy. In certain such embodiments, the
sequence of steps may be insert needle, deploy filaments, apply RF
energy, retract filaments, reposition needle, and repeat as
appropriate to create each desired lesion. Such a procedure may be
conducted, for example, using a needle capable of producing a
lesion symmetric to a central longitudinal axis of the needle
(e.g., the needle of FIG. 9).
3. Thoracic RF Neurotom of a Medial Branch Nerve.
[0224] This process may include using a needle that enables the
creation of lesions which are offset from the central longitudinal
axis of the needle. Successful treatment of thoracic z-joint pain
using radiofrequency ablation of relevant medial branch nerves can
be challenging owing to the inconsistent medial branch location in
the intertransverse space, especially levels T5-T8. A needle
without filaments is generally positioned at multiple locations in
the intertransverse space to achieve sufficient tissue ablation for
successful medial branch neurotomy. The procedure will be described
as being performed on an intertransverse space between adjacent
vertebrae 1301, 1302 of the T5 to T8 thoracic vertebrae using FIG.
14 and the needle 103 of FIG. 2A. It should be understood that
other embodiments of needles described herein and/or other
vertebrae may be used in the described procedure or variations
thereof.
[0225] The process may include obtaining a segmental
anteroposterior image at target level defined by counting from T1
and T12. This may be followed by obtaining an image that is
ipsalateral oblique about 8.degree. to about 15.degree.
off-sagittal plane of the spine to visualize costotransverse joint
lucency clearly. This can allow improved visualization of the
superior-lateral transverse process, especially in osteopenic
patients. The angle can aid in directing the probe to a thoracic
anatomic safe zone medial to the lung, reducing risk of
pneumothorax.
[0226] The skin entry site for the needle 103 may be over the most
inferior aspect of transverse process slightly medial to
costotransverse joint. Inserting the needle 103 may include
navigating the device over the transverse process over the bone to
touch the superior transverse process slightly medial to the
costotransverse joint. The process may include checking
anteroposterior imaging to demonstrate that the tip 201 of the
needle 103 is at the superolateral corner of the transverse
process. The process may also include checking a contralateral
oblique image view (e.g., at .+-.15.degree.) to demonstrate, for
example in "Pinnochio" view, the target transverse process in an
elongate fashion. This view can be useful for showing the tip 201
of the needle 103 in relationship to the superolateral margin of
the transverse process subadjacent to the targeted medial branch
nerve. The process may include retracting the tip 201 slightly
(e.g., about 1 mm to about 3 mm). In some embodiments, retracting
the tip 201 positions the ports at the superior edge of the process
(e.g., visible with a radiopaque marker).
[0227] In some embodiments, medial to lateral placement may be
performed entering the skin beneath the segmental spinous process,
and navigating the needle 103 over the transverse process to
contact a point just proximal to the superolateral corner of the
transverse process. The tip 201 may then be advanced to approximate
the exit port 304a, 304b of the filaments 206a, 206b with the
superior margin of the transverse process, and the filaments 206a,
206b are deployed.
[0228] The process may include rotating the needle 103 such that
the midpoint 502 is oriented toward the intertransverse space
between the vertebrae 1301, 1302 and the medial branch nerve 1303
that is positioned therein. Next, the filaments 206a, 206b may be
advanced ventral into the intertransverse space between the
vertebrae 1301, 1302 to the deployed position. The position of the
needle 103 and deployed filaments 206a, 206b may be verified using
fluoroscopy (e.g., using lateral imaging) and/or stimulation (e.g.,
motor and/or sensory), for example to rule out proximity to ventral
ramus. In some embodiments, the filaments 206a, 206b are deployed
in a ventral direction in the intratransverse space, which may be
confirmed by obtaining lateral. The RF probe 401 may be inserted
into the lumen 222 such that RF energy emanating from the probe 103
will be conducted by the tip 201 and the filaments 206a, 206b to
the target medial branch nerve 1303. Next, RF energy may be applied
to the RF probe 401. The RF energy emanating from the needle 103
may be preferentially biased toward the volume between the
vertebrae 1301, 1302. The lesion created by such a procedure may,
for example, have a maximum cross-sectional dimension of between
about 8 mm and about 10 mm, and may ablate a corresponding portion
of the medial branch nerve 1303. This method can treat the medial
branch as it curves out of the intratransverse space emerging into
the posterior compartment of the back. The directional bias of the
lesion may advantageously heat towards the target and away from the
skin.
[0229] It is noted that thoracic RF neurotomy performed on other
thoracic vertebrae may call for different sizes of lesions. For
example, thoracic RF neurotomy performed on the T3-T4 vertebrae may
require a smaller lesion volume than the herein-described
procedure, and thoracic RF neurotomy performed on the T1-T2
vertebrae may require a still smaller lesion volume. As described
herein, the deployment of the filaments of the needle 103 may be
varied to achieve such desired target lesion volumes, or different
needles may be used (e.g., having shorter filaments in the fully
deployed position).
4. Cervical Medial Branch RF Neurotomy.
[0230] Embodiments of needles described herein (e.g., the needle
103 of FIG. 2A) are capable of creating a volume of tissue ablation
necessary for complete denervation of the cervical zygapophyseal
joints, including the C2/3 cervical zygapophyseal joint (z-joint).
Tissue ablation for cervical z-joint using embodiments of needles
described herein may be accomplished using a single placement and
single heating cycle. Such single placement and single heating
cycle may avoid unnecessary tissue damage from multiple placements
of a filament-free needle, and unintended injury to collateral
tissue caused by excessive lesioning. The zone of ablation can be
designed to provide sufficient and necessary tissue coagulation for
a successful procedure, and thus may be expected to improve the
outcomes of patients undergoing spinal radiofrequency
neurotomy.
[0231] A cervical medial branch RF neurotomy procedure will be
described as being performed on the third occipital nerve at the
C2/3 z-joint using the needle 103 as shown in FIG. 15. In FIG. 15,
the needle 103 is positioned between the C2 vertebra 1401 and the
C3 vertebra 1402.
[0232] In a first step, the patient may be placed in a prone
position on a radiolucent table suited to performing
fluoroscopically guided spinal procedures. Sedation may be
administered. The patient's head may be rotated away from the
targeted side. Sterile skin prep and draping may be performed using
standard well-described surgical techniques.
[0233] For Third Occipital Nerve (TON) ablation (C2/3 joint
innervation) the lateral aspect of the C2/3 Z-joint is located
under either parasagittal or, alternatively, ipsilateral oblique
rotation of less than or equal to about 30.degree. (e.g., between
about 20.degree. and about 30.degree.) of obliquity relative to the
true sagittal plane of the cervical spine. The skin entry point may
be infiltrated with local anesthetic. Then, the tip 201 of the
needle 103 is moved over the most lateral aspect of bone of the
articular pillar at the juncture of the C2/3 z-joint to a first
position contacting bone proximate to the most posterior and
lateral aspect of the z-joint complex, for example using a
"gun-barrel" technique to touch the most lateral and posterior
aspect of the articular pillar at the point of maximal concavity
for level below C2/3 or at the point of maximal convexity at the
C2/3 level when targeting the TON.
[0234] Once boney contact is made, the needle 103 may be retracted
a predetermined distance (e.g., between about 1 mm and about 3 mm)
and the filaments are deployed towards the lateral aspect of the
C2/3 z-joint. The filaments will spread to encompass anticipated
rostrocaudal variation in the target nerve location. The angle of
the filaments with respect to the tip may effectively cover the
ventral aspect of the articular pillar up to the border of the
superior articular process, thus incorporating benefits of a
30.degree. oblique pass. The needle 103 may be rotated about a
central longitudinal axis prior to filament deployment to ensure
that deployment will occur in the desired direction.
[0235] Multiplanar fluoroscopic imaging may then be employed to
verify that the tip and the filaments are positioned as desired.
For example, it may be verified that the filaments are positioned
straddling the lateral joint lucency, and posterior to the C2/3
neural foramen. Useful imaging angles include anterior-posterior
(AP), lateral, and contralateral oblique (Sluijter) views. To
further verify adequate positioning of the needle 103, motor
stimulation may be performed by delivering a voltage (e.g., up to
about 2 volts) at about 2 Hz to the tip 201 and filaments and/or
sensory stimulation may be performed at appropriate voltage (e.g.,
between about 0.4 volts and about 1 volt) and frequency (e.g.,
about 50 Hz).
[0236] After position verification, RF energy may be applied to the
tip and the plurality of filaments to generate heat that ablates a
portion of the third occipital nerve. The cross-sectional
dimensions of the lesion (e.g., between about 8 mm and about 10 mm)
can incorporate all medial branches as well as the TON, which has a
nerve diameter of about 1.5 mm. The directional nature of the
lesion, offset towards the filaments, provides a beneficial measure
of safety regarding undesired thermal damage to the skin and to
collateral structures. Safety concerns may be further satisfied by
fluoroscopic observation of the filaments dorsal to the
intervertebral foramen and/or lack of ventral ramus activation
during stimulation (e.g., with 2 Hz and 2 volts). After lesioning,
the device may be removed. For levels below the C2/3 z-joint, the
procedure may be similar than as described herein with respect to
the third occipital nerve, with the exception that the initial
boney contact target is at the waist of inflection point of the
articular pillar.
[0237] Other spinal RF procedures may also benefit from the
asymmetrical application of RF energy from embodiments of the
needles described herein. Such asymmetry may, for example, be used
to project RF energy in a desired direction and/or limit the
projection of RF energy in undesired directions. The configuration
of the filaments may be selected for a particular application to
produce a desired size, shape, and/or location (relative to the
needle tip) of a lesion within the patient. The location of the
lesion may be offset distally and/or laterally from the tip of the
needle as desired for a particular application.
[0238] It will be appreciated that the delivery of RF energy to
tissue in the anatomy can be practiced for a multitude of reasons,
and embodiments of the needles described herein may be adapted
(e.g., modified or scaled) for use in other medical procedures. For
example, embodiments of needles described herein could be used to
deliver RF energy as a means to cauterize "feeder vessels," such as
in bleeding ulcers and/or in orthopedic applications. For another
example, embodiments of the needles described herein could be
adapted for use in procedures such as cardiac ablation, in which
cardiac tissue is destroyed in an effort to restore a normal
electrical rhythm in the heart. Certain such uses could further
benefit from the ability of embodiments of needles described herein
to deliver fluid through a lumen since, for example, emerging
procedures in cardiac therapy may require the ability to deliver
stem cells, vascular endothelial growth factor (VEGF), or other
growth factors to cardiac tissue. The ability to steer embodiments
of the needle described herein may provide significant benefit in
the field of cardiovascular drug delivery.
[0239] For example, a needle may be adapted for use in vertebral
disc heating. A primary longer needle (e.g., having a length of
about 15 cm and a tip with an uninsulated active portion having a
length of about 2 mm, although other dimensions are also possible),
is placed into the post posterolateral margin of a painful
intervertebral disc, for example as described elsewhere for
provocation discography and/or therapeutic disc access procedures
such as Dekompressor.RTM. discectomy and disc biacuplasty. Once
positioned in the posterior annulus, as confirmed with
fluororscopy, tactile feedback, and/or characteristic impedance
readings, a single filament is deployed to traverse the posterior
annulus in a lateral to medial fashion in the lamella of the
annulus fibrosis, for example as illustrated in FIG. 18A, which is
an axial view of posterior oblique needle entry with the main axial
tip in the posterior annulus and deployed a filament moving lateral
to medial in the lamella of the posterior annulus, and FIG. 18B,
which is a saggital view with a filament moving across the
posterior annulus from lateral to medial.
[0240] In some embodiments, the filament may act as a thermocouple
(e.g., comprising a material having thermosensing properties as
described herein) to allow precise measurement of actual
temperatures of the annulus. In some embodiments, the filament
includes a lumen configured to allow injection of therapeutic
substances (e.g., methylene-blue) upon withdrawal for substantially
simultaneous chemo-thermo-neurolysis and/or to allow injection of
contrast agent for confirmation of intraannular placement that is
definite, for example as opposed to potentially dangerous placement
in the spinal canal or futile placement in the nucleus pulposus. In
some embodiments, the filament has an exit angle greater than about
30.degree.. In some embodiments, the filament includes a beveled
Quincke tip oriented to bias away from the spinal canal upon
advancement, as needles in tissue track away from bevel angles. In
some embodiments, the deployed filament has a length between about
10 mm and about 12 mm. In some embodiments, the needle does not
include a lumen for injection of liquid. In certain such
embodiments, the area not occupied by a lumen may be used for the
filament, which may be more complicated due to use as a
thermocouple and/or including a lumen.
[0241] Bipolar or monopolar RF energy is applied to the tip and to
the filament, creating a zone of therapeutic heating across the
posterior disc annulus and resulting in destruction of the pain
fibers in approximately the outer third of the annulus. The
procedure may be repeated on the opposite side. In some
embodiments, the needle includes a plurality of deployable
filaments, and gap between the filaments (e.g., the distance 604 in
FIG. 6) is between about 2 mm and about 10 mm, between about 4 mm
and about 8 mm, between about 5 mm and about 7 mm (e.g., about 6
mm), combinations thereof, and the like.
Example 1
[0242] Sections of raw muscle tissue were allowed to equilibrate to
37.degree. C. in a distilled water bath. A needle with tines
deployed was positioned to contact the tissue surface in 10 trials
and was inserted into tissue in 10 trials. A Radionics RFG 3C RF
generator energy source was set at 75.degree. C. for 80 seconds.
Propagation of tissue coagulation was documented with video and a
calibrated Flir T-400 thermal camera. Tissue samples were sectioned
and coagulation zones measured. Infrared observation demonstrated
symmetric and homogenous lesion progression without hot spots or
focal over-impeding. Calculated volume averaged 467.+-.71
mm.sup.3/lesion. Topography was elongate spheroid offset from the
central axis toward the filaments. Thus, the needle reliably
produced lesions that are potentially useful in spinal
applications.
Example 2
[0243] A 47 year-old male with recalcitrant right-sided lumbar
zygapophysial joint pain presented for radiofrequency medial branch
neurotomy. The diagnosis had been made by greater than 80% relief
documented following both intraarticular z-joint injection and
confirmatory medial branch blocks.
[0244] The patient was placed in a prone position on the
fluoroscopy table and standard monitors were applied. No sedation
was administered. The lumbar region was extensively prepped with
chlorhexidine-alcohol and draped in routine sterile surgical
fashion. The C-arm was adjusted to visualize a true AP of the L4/5
intervertebral disc space with vertebral end plates squared-off,
and spinous process positioned between the pedicle shadows. The
C-arm was rotated 30.degree.-40.degree. ipsilateral to the target
joint until the base of the SAP of the L4 and L5 were clearly
visualized, A target point was identified at the midpoint of the
base of the SAP, and the overlying skin and subcutaneous tissues
were infiltrated with 1.5% lidocaine. A small skin nick was made
with an 18-gauge needle to facilitate placement of an embodiment of
the needles described herein. Once skin anesthesia was established,
the needle, with filaments in the retracted position, was advanced
using a gun-barrel approach until boney contact was made with the
base of the SAP. The needle was then retracted off the bone
slightly, and using the indentation on the hub for orientation, the
actuator was rotated 360.degree. to fully deploy the filaments.
Filaments were felt to touch bone at the base of the SAP. AP,
oblique, and lateral images were obtained to document the placement
and to confirm that the filaments were directed toward the SAP. In
this position, the lesion was biased to cover any variant medial
branch situated higher up the SAP. If the filaments were not
directed in an ideal fashion, they were retracted, the device was
rotated as necessary, and the filaments were redeployed. Motor
stimulation at a frequency of 2 Hz up to 2 volts was incrementally
administered with brisk activation of the multifidus, but with no
activation of any ventral root inenervated musculature. Sensory
stimulation at 50 Hz at 0.6 volts elicited a concordant aching in
the distribution of the patient's pain. A 22-gauge, 10 cm, 10 mm
active tip RFK connected to an independently grounded second RF
generator was placed sequentially at the following targets for in
vivo thermometry: (1) Most inferior and dorsal location in the
supra-segmental neural foramen evaluating the potential for thermal
injury of spinal nerve; (2) At a point lateral on the transverse
process approximating the location of intermediate/lateral branches
of the posterior primary rami; (3) At or near the central axis of
the needle during stable heating; (4) On the SAP at the base and
successively higher on mamilliary process to evaluate heating on
the region of potential MB variation (up the SAP). The process was
then repeated for denervation of the L5.
[0245] Following the confirmation of safe and optimal placement by
fluoroscopy and stimulation, the heating protocol was initiated
based on previous branch testing in egg white and chicken meat. The
protocol included: 45.degree. C. for 15-30 seconds, await rapid
temperature increase signaling primary consolidation of heating and
biophysical changes around core axis; 50.degree. C. for 15 seconds;
60.degree. C. for 15 seconds; 70.degree. C. for 10 seconds to
record foraminal temperatures only.
[0246] Generator parameters during ablation were appropriate and
within the tolerance range for a generically programmed RF
generator. The lower starting impedance, relative to a monopolar
needle, may be explained by greatly increased conductive surface of
the needle. Brief temperature fluctuation was noted as the lesion
propagated to encompass the central axis housing the thermocouple.
It is anticipated that changes in the generator software may be
useful to support various embodiments of the described device.
Impedance readings were 75 ohms to 250 ohms. Power ranges were 2
watts to 11 watts, typically 3 watts to 4 watts after 10 seconds
into the procedure.
[0247] The thermal mapping results were as follows: (1) Perineural
temperatures (neurogram obtained via TC2) at the supra-adjacent
spinal nerve did not increase from a 38.degree. C. baseline; (2)
Temperature readings from the TC2 placed near the central axis of
the needle reflected delivered temperature from the generator; (3)
Temperature readings from the base of the SAP to relatively dorsal
position on the SAP exceed the neuroablative threshold of
45.degree. C.
[0248] The patient experienced minimal discomfort following the
procedure. For the sake of full disclosure, it is noted that the
patient is an inventor of the present application. No postoperative
analgesics were required. The patient reported near complete
relieve of his right-sided low back pain within 10 days of the
procedure. Bilateral paraspinal EMG at L3, L4, and L5 was performed
20 days after the RF procedure, as documented in Table 1:
TABLE-US-00001 TABLE 1 Paraspinal EMG Side Muscle Nerve Root Ins
Act Fibs Psw Left L3 Parasp Rami L3 Nml Nml Nml Left L4 Parasp Rami
L4 Nml Nml Nml Left L5 Parasp Rami L5 Nml Nml Nml Right L3 Parasp
Rami L3 Nml Nml Nml Right L4 Parasp Rami L4 *Incr *1+ *1+ Right L5
Parasp Rami L5 *Incr *1+ *1+ *Needle evaluation of the right L4
paraspinal and the right L5 paraspinal muscles showed increased
insertional activity and slightly increased spontaneous activity.
*All remaining muscles showed no evidence of electrical
instability.
There was electrodiagnostic evidence of active and acute
denervation of the right lumbar paraspinals at the L4 and L5
levels. The contralateral left-sided paraspinals appeared normal.
These findings are consistent with the clinical history of recent
right lumbar radiofrequency rhizotomy.
[0249] Thus, the needle was safely and effectively used to
accomplish lumbar medial branch neurotomy. Thermal mapping
demonstrated a safe and effective isotherm consistent with bench
predictions, and EMG of the lumbar paraspinals demonstrated
objective evidence of medial branch coagulation. The needle appears
to extend beneficially on existing techniques and technology. For a
first example, facilitated placement for lumbar medial branch
neurotomy using "down-the-beam" technique akin to diagnostic medial
branch block. This approach can be applied to other spinal targets
such as cervical z-joint neurotomy, thoracic z-joint neurotomy,
sacroiliac joint denervation, central innercation of the lateral
C1-2 joint, RF neurotomy thoracic sympathetic chain, RF neurotomy
sphlancnic chain at T10, 11, 12, RF neurotomy lumbar sympathetic
pain, and RF neurotomy superior hypogastric plexus. For a second
example, lab testing and in vivo thermal data demonstrates a large
volume suited for efficiently dealing with common variations in
afferent sensory pathways. The lesion can be directed relative to
the central longitudinal axis of the needle toward targets and away
from sensitive collateral structures. For a third example, the
needle can deliver meaningful motor and/or sensory stimulation for
documentation of safe placement. For a fourth example, lesion
topography is driven by needle design, and does not require high
temperatures (e.g., greater than 80.degree. C.) for extended times.
It is believed that 60.degree. C. for 60 seconds is adequate for
most targets. Reduced procedural time and/or lower temperatures
should translate to fewer complications, expedited recovery, and/or
diminished incidence of postoperative pain syndromes/dysesthesias.
For a fifth example, relative to other large field lesion
technology, the needle is of a uncomplicated and robust design,
does not require additional support equipment, and is economical to
manufacture.
[0250] Although this invention has been disclosed in the context of
certain embodiments and examples, it will be understood by those
skilled in the art that the invention extends beyond the
specifically disclosed embodiments to other alternative embodiments
and/or uses of the invention and obvious modifications and
equivalents thereof. In addition, while several variations of the
embodiments of the invention have been shown and described in
detail, other modifications, which are within the scope of this
invention, will be readily apparent to those of skill in the art
based upon this disclosure. It is also contemplated that various
combinations or sub-combinations of the specific features and
aspects of the embodiments may be made and still fall within the
scope of the invention. It should be understood that various
features and aspects of the disclosed embodiments can be combined
with, or substituted for, one another in order to form varying
modes of the embodiments of the disclosed invention. Thus, it is
intended that the scope of the invention herein disclosed should
not be limited by the particular embodiments described herein.
* * * * *