U.S. patent application number 14/191446 was filed with the patent office on 2015-08-27 for nerve sparing treatment systems and methods.
The applicant listed for this patent is Dan David Albeck, Tzachi Itzhak Sabati. Invention is credited to Dan David Albeck, Tzachi Itzhak Sabati.
Application Number | 20150238259 14/191446 |
Document ID | / |
Family ID | 53881120 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150238259 |
Kind Code |
A1 |
Albeck; Dan David ; et
al. |
August 27, 2015 |
NERVE SPARING TREATMENT SYSTEMS AND METHODS
Abstract
Treatment systems are provided, which comprise a treatment
element applying a treatment to a tissue, a stimulation element
optically stimulating nerves in the tissue, a sensing unit sensing
an electrical signal produced by nerves in the tissue in response
to the optical stimulation, and a control unit controlling the
application of the treatment according to the sensed signal. The
systems and methods are used to avoid damaging nerves by sensing
them during operation and immediately before local treatment
application and preventing energy emission when the treatment tool
is too close to specified nerves. Additional electric stimulation
may be provided to enable avoidance of nerve damages on a larger
scale, the treatment may be applied by a cold laser, and the
control unit may control the treatment in realtime and in a closed
loop and immediate prevent further treatment upon sensing optically
stimulated nerves.
Inventors: |
Albeck; Dan David; (Givat
Shmuel, IL) ; Sabati; Tzachi Itzhak; (Megadim,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Albeck; Dan David
Sabati; Tzachi Itzhak |
Givat Shmuel
Megadim |
|
IL
IL |
|
|
Family ID: |
53881120 |
Appl. No.: |
14/191446 |
Filed: |
February 27, 2014 |
Current U.S.
Class: |
606/3 ; 606/10;
606/12 |
Current CPC
Class: |
A61B 5/4893 20130101;
A61B 18/1492 20130101; A61B 2018/20361 20170501; A61B 2018/00577
20130101; A61B 2018/00547 20130101; A61B 2018/00898 20130101; A61B
2017/00039 20130101; A61B 18/22 20130101; A61B 2018/00339 20130101;
A61B 2018/00732 20130101; A61B 5/4836 20130101; A61B 2018/0066
20130101; A61N 5/0622 20130101; A61B 2018/00839 20130101; A61B
2018/00904 20130101; A61B 18/1815 20130101; A61B 2018/00702
20130101; A61B 2017/00119 20130101; A61B 2017/00176 20130101; A61B
2018/00642 20130101; A61B 2018/00708 20130101 |
International
Class: |
A61B 18/22 20060101
A61B018/22 |
Claims
1. A treatment system comprising: a treatment unit comprising a
treatment element arranged to apply a treatment to a tissue, an
optical stimulation unit comprising an optical stimulation element
arranged to optically stimulate nerves in the tissue, a sensing
unit comprising at least one sensing electrode arranged to sense an
electrical signal produced by nerves in the tissue in response to
said optical stimulation, and a control unit arranged to control
the application of the treatment in realtime and in a closed loop
according to the sensed electrical signal.
2. The treatment system of claim 1, wherein the optical stimulation
element is configured to stimulate nerves in a larger tissue volume
than the treated tissue volume.
3. The treatment system of claim 1, wherein the treatment is
optical and the optical stimulation element is configured to
operate at a wavelength or a wavelength range that has a higher
penetration coefficient in the treated tissue than a wavelength or
a wavelength range in which the optical treatment element
operates.
4. The treatment system of claim 3, wherein the wavelength or the
wavelength range in which the optical stimulation element operates
is adjustable.
5. The treatment system of claim 1, wherein the treatment is
optical and the optical stimulation element is configured to have a
larger incidence spot size than the optical treatment element.
6. The treatment system of claim 1, wherein the treatment element
is an ablative cold laser.
7. The treatment system of claim 1, wherein the optical stimulation
element is a non-ablative laser.
8. The treatment system of claim 1 wherein at least one of the
treatment element and the optical stimulation element is a laser in
a wavelength range within at least one of: 1.35-1.55 .mu.m,
1.85-2.5 .mu.m and 9-11 .mu.m.
9. The treatment system of claim 1, wherein the treatment element
and the optical stimulation element are lasers which are delivered
through at least one of: a single fiber, different fiber cores in a
single fiber and different fibers; and differ in at least one of:
their respective wavelength or wavelength ranges, their respective
incident spot sizes, their respective tissue penetration
coefficient and their respective numerical apertures.
10. The treatment system of claim 1, wherein the treatment element
is an optical fiber or a waveguide, and the sensing electrode is
attached to or integrated in the treatment element.
11. The treatment system of claim 1, wherein the sensing electrode
is a non-contact sensor arranged to sense at least one of: a
radiofrequency signal, an electric field and a magnetic field.
12. The treatment system of claim 1, wherein the control unit is
arranged to immediately prevent treatment application upon sensing,
by the sensing unit, of the electrical signal produced by nerves in
the tissue in response to said optical stimulation.
13. The treatment system of claim 1, wherein the control unit is
arranged to control the optical stimulation to intersperse the
optical nerve stimulation among pulses of treatment application and
to immediately prevent a consequent pulse of treatment application
upon detection of nerve response to the optical stimulation.
14. The treatment system of claim 1, further comprising an
electrical stimulation unit arranged to electrically stimulate
nerves, wherein the sensing unit is further arranged to sense an
electrical signal produced by nerves in the tissue in response to
said electrical stimulation.
15. The treatment system of claim 14, wherein the optical
stimulation element is configured to stimulate nerves in a larger
tissue volume than the treated tissue volume, and the electrical
stimulation unit is arranged to stimulate nerves in a larger tissue
volume than the optically stimulated tissue volume.
16. A treatment system of claim 14, wherein the control unit is
arranged to provide an alert upon the sensing of the electrical
signal in response to the electrical stimulation.
17. A treatment system of claim 14, wherein the control unit is
arrange to reconfigure treatment parameters upon the sensing of the
electrical signal in response to the electrical stimulation.
18. The treatment system of claim 14, wherein the electrical
stimulation unit comprises an electrical stimulation element which
is associated with the treatment element.
19. A treatment system comprising: a treatment unit comprising an
optical fiber arranged to apply a cold laser ablative treatment to
a tissue, an optical stimulation unit arranged to optically
stimulate nerves in the tissue, an electrical stimulation unit
arranged to electrically stimulate nerves, a sensing unit
comprising at least one sensing electrode arranged to sense an
electrical signal produced by nerves in the tissue in response to
said optical stimulation, and to sense an electrical signal
produced by nerves in the tissue in response to said electrical
stimulation, and a control unit arranged to control the optical
stimulation and the electrical stimulation and control the
application of the ablative treatment in realtime and in a closed
loop according to the sensed electrical signal produced by nerves
in the tissue in response to said optical stimulation.
20. The treatment system of claim 19, wherein the control unit is
arranged to immediately prevent treatment application upon sensing,
by the sensing unit, of the electrical signal produced by nerves in
the tissue in response to said optical stimulation, and to modulate
treatment application upon sensing, by the sensing unit, of the
electrical signal produced by nerves in the tissue in response to
said electrical stimulation.
21. A method comprising configuring a tissue treatment system to
optically stimulate nerves in the tissue, sense an electrical
signal produced by nerves in the tissue in response to said optical
stimulation and control the treatment according to the sensed
electrical signal.
22. The method of claim 21, wherein a treated tissue volume is
arranged to be enclosed within a stimulated tissue volume.
23. The method of claim 21, wherein the treatment is light-based
and further comprising configuring the optical stimulation and the
light-based treatment to differ in at least one of: their
respective wavelength ranges, their respective incident spot sizes,
their respective tissue penetration coefficient and their
respective numerical apertures.
24. The method of claim 21, further comprising immediately
preventing treatment application upon sensing the electrical signal
produced by nerves in the tissue in response to said optical
stimulation.
25. The method of claim 21, further comprising interspersing the
optical nerve stimulation among pulses of treatment application and
immediately preventing a consequent pulse of treatment application
upon detection of nerve response to the optical stimulation.
26. The method of claim 21, further comprising electrically
stimulating nerves and sensing an electrical signal produced by
nerves in the tissue in response to said electrical
stimulation.
27. The method of claim 26, wherein a treated tissue volume is
arranged to be enclosed within an optically stimulated tissue
volume and the optically stimulated tissue volume is arranged to be
enclosed within an electrically stimulated tissue volume.
28. The method of claim 26, further comprising providing an alert
upon the sensing of the electrical signal in response to the
electrical stimulation.
29. The method of claim 26, further comprising reconfiguring
treatment parameters upon the sensing of the electrical signal in
response to the electrical stimulation.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to the field of invasive
surgery, and more particularly, to treatment tools which avoid
damaging nerves.
[0003] 2. Discussion of Related Art
[0004] It is common that nerves are damaged during surgical
procedures, resulting in malfunctioning of associated sensory and
motor systems. At least some of the damage is not a necessary
result in view of the surgical targets and is in principle
avoidable. Current technology includes mapping and/or monitoring of
nerves by measuring nerve or organ response to electrical
stimulation.
SUMMARY OF THE INVENTION
[0005] One aspect of the present invention provides a treatment
system comprising a treatment unit comprising a treatment element
arranged to apply a treatment to a tissue, a stimulation unit
comprising a stimulation element arranged to stimulate nerves in
the tissue, a sensing unit comprising a sensing electrode arranged
to sense an electrical signal produced by nerves in the tissue in
response to said stimulation, and a control unit arranged to
control the application of the treatment according to the sensed
electrical signal.
[0006] These, additional, and/or other aspects and/or advantages of
the present invention are set forth in the detailed description
which follows; possibly inferable from the detailed description;
and/or learnable by practice of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a better understanding of embodiments of the invention
and to show how the same may be carried into effect, reference will
now be made, purely by way of example, to the accompanying drawings
in which like numerals designate corresponding elements or sections
throughout.
[0008] In the accompanying drawings:
[0009] FIGS. 1A and 1B are high level schematic illustrations of
treatment systems for treating the prostate and for microsurgery,
respectively, according to some embodiments of the invention.
[0010] FIGS. 2A-2D are illustrations of absorption and penetration
of electromagnetic radiation with respect to water, fat and blood
as proxies for the absorption and penetration of electromagnetic
radiation into tissue.
[0011] FIG. 3A is a schematic high level illustration of a
treatment signal delivered by treatment element such as an ablative
laser, a stimulation signal delivered by stimulation element such
as a non-ablative laser and a sensing signal as sensed by sensing
electrode, according to some embodiments of the invention.
[0012] FIGS. 3B and 3C are high level schematic flowcharts
illustrating optical and optionally electric stimulation in a
closed loop control of a treatment tool, according to some
embodiments of the invention.
[0013] FIG. 3D schematically illustrates tissue volumes which are
affected, respectively, by the treatment and by the stimulation
elements, according to some embodiments of the invention.
[0014] FIGS. 4A-4E are high level schematic illustrations of
element configurations, according to some embodiments of the
invention.
[0015] FIGS. 5A-5E are high level schematic illustrations of
configurations of the treatment fiber, with the treatment element
and the stimulation element, optional electric stimulation element
and the sensing electrode, according to some embodiments of the
invention.
[0016] FIG. 6 is a high level schematic flowchart illustrating a
method according to some embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Prior to the detailed description being set forth, it may be
helpful to set forth definitions of certain terms that will be used
hereinafter.
[0018] The terms "light-based" and "optical" as used in this
application refer to electromagnetic radiation in the visible range
as well as in the near infrared range.
[0019] The term "cold laser" as used in this application refers to
a laser that is configured to ablate tissue while preventing stress
waves or heat from propagating beyond the interaction volume
relative to a shortest dimension of the interaction volume. For
example, a cold laser may deliver pulses or fast trains of pulses
having energy per pulse or per train of pulses that is sufficient
to heat an interaction volume of the tissue above the spinodal
decomposition threshold for water within the pulse duration, and
cause sufficient pressure for ejection of the target tissue. Such a
cold laser may have the duration of the pulse or the train of
pulses selected to be sufficiently short to prevent stress waves or
heat from propagating beyond the interaction volume relative to a
shortest dimension of the interaction volume. For example, such
cold laser may comprise flash vaporization surgical systems such as
those described in U.S. Patent Application Publication No.
2013/0035676, producing laser pulses having a wavelength between
1400 and 1520 nm or between 1860 and 2500 nm, having between 1 and
40 milli-joules per pulse, and having a pulse duration less than
200 nanoseconds.
[0020] The term "closed loop" as used in this application refers to
a method of control which is automatic and does not involve manual
activity.
[0021] With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of the preferred embodiments of
the present invention only, and are presented in the cause of
providing what is believed to be the most useful and readily
understood description of the principles and conceptual aspects of
the invention. In this regard, no attempt is made to show
structural details of the invention in more detail than is
necessary for a fundamental understanding of the invention, the
description taken with the drawings making apparent to those
skilled in the art how the several forms of the invention may be
embodied in practice.
[0022] Before at least one embodiment of the invention is explained
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
applicable to other embodiments or of being practiced or carried
out in various ways. Also, it is to be understood that the
phraseology and terminology employed herein is for the purpose of
description and should not be regarded as limiting.
[0023] The systems and methods which are described below optically
stimulate nerves in a tissue volume which is about to be treated
and are tuned to measure responses from the stimulated nerves
immediately before the actual activation of the treatment, in real
time. In case nerves are detected in the tissue volume, the
treatment may be prevented, modified or attenuated in real time to
avoid unnecessary damage to the nerves. In case of an optical
treatment (such as a treatment using ablative laser), the optical
stimulation may be advantageously be carried out in a configuration
in which the stimulation radiation is arranged to penetrate the
tissue into a larger volume than the optical treatment radiation.
Such a configuration maintains safety margins to compensate for
system, tissue, and procedure variations and for residual heat
dissipation thermal damage. One option to ensure this safety margin
is by using different wavelengths for the treatment and stimulation
radiation in a way that the stimulation radiation penetrates the
tissue into a larger volume than the treatment radiation. An
additional electrical stimulation may further enhance nerve
detection in and around the treated volume. Advantageously, the
invention allows the surgeon to avoid iatrogenic damage to nerves.
The systems and methods allow the surgeon to avoid mechanical
damage (stretching, squashing, tearing, cutting, clamping, etc.) to
nerves by identifying nerves in the treated region as well as to
avoid thermal and electrical damages by using cold laser and/or
attenuating or switching off the treatment energy when the
treatment tool is too close to the nerves (used to prevent
mechanical damage as well). Advantageously, combining non-contact
optical treatment with optical stimulation and adjusting the
treatment energy with respect to the proximity to the nerve allow
the practitioner to treat tissue that is much closer to the nerves
than is possible in conventional approaches without damaging the
nerves. With respect to current surgical technologies and methods
which do not sense nerves at all, or sense nerves only at a crude
resolution and/or at specified time periods, the current invention
advantageously enables high resolution localized measurements,
enables realtime nerve sensing as well as a closed loop operation
of the treatment tool which automatically avoids damaging nerves.
For example, tools of the current invention may be used to remove
tumors that are adjacent to nerves, scars on nerves, etc. by
ablating the material to be removed up to the very circumference of
the nerves, without damaging the nerves.
[0024] Specifically, in certain embodiments, electrical stimulation
and respective sensing may be used as a long range sensing
mechanism that allows avoiding mechanical damage to nerves, cold
laser may be used as the treatment tool to avoid thermal and
electrical damages to nerves, and optical stimulation and
respective sensing may be used to prevent fine scale damage to
nerves (accidental cutting), optionally automatically in a closed
loop and in realtime. The latter aspect can be seen as turning the
treatment tool into a "smart knife" that automatically avoids
severing nerves in its way.
[0025] FIGS. 1A and 1B are high level schematic illustrations of
treatment systems 100 for treating prostate 90 and for microsurgery
at a back region 90, respectively, according to some embodiments of
the invention. Treatment system 100 may be applied to treat any
tissue region 90 and is configured to avoid damage to nerves and to
apply nerve-preserving treatments to various body regions 90.
[0026] The surroundings of the prostate, the vertebrae (and of most
other tissues and organs 90) comprise nerves 80 which are commonly
injured during prior art surgical intervention, due to the
difficulty in distinguishing them from surrounding tissue and/or
due to other characteristics of the surgical procedure (a similar
situation exists in, e.g., thyroid related operations, brain
operations, spinal cord operations, tumors that contact nerves,
nerve scars etc.). Advantageously, the proposed systems and methods
significantly reduce or even eliminate this injury risk.
Advantageously, system 100 may be used to avoid damaging nerves by
applying the sensing and treatment in a sequential mode in which
every treatment signal or a few treatment signals follows a sensing
signal and preventing energy emission when the treatment tool is
too close to specified nerves.
[0027] Treatment system 100 comprises a treatment unit 110
comprising a treatment element or tool 115 (e.g., an optical fiber
or a waveguide, a plasma treatment tool, an RF electrode etc.)
arranged to apply a treatment to a tissue 95, an optical
stimulation unit 120 comprising an optical stimulation element 125
arranged to optically stimulate nerves 80 in tissue 95, a sensing
unit 130 comprising at least one sensing element 135 (e.g., one or
more electrode(s) or one or more non-contact sensor(s), which may
be associated with treatment element 115 or positioned on the nerve
tract or on tissue controlled by respective nerves) arranged to
sense an electrical signal produced by nerves 80 in response to the
optical stimulation by optical stimulation element 125 and
delivered or guided along the nerves, and a control unit 140
arranged to control the application of the treatment according to
the sensed electrical signal, for example in realtime and/or in a
closed loop (i.e., automatically and not requiring manual
intervention). In certain embodiments, sensing element(s) 135 may
be deployed at a specified spatial arrangement, and/or be
calibrated or tuned to cover a specified range and/or type of
nerves and target tissues and thus enable a respective required
monitoring requirement.
[0028] For example, in case of optical treatment, control unit 140
may control stimulation and ablation pulses parameters like
intensity, pulse width, repetition rates and also the sequencing
between the stimulation and treatment pulses. Control unit 140 may
be arranged to immediately prevent treatment application upon
sensing, by sensing unit 130, of the electrical signal produced by
nerves in the tissue in response to the optical stimulation. In
certain embodiments, control unit 140 may be arranged to control
the optical stimulation to intersperse the optical nerve
stimulation among pulses of treatment application and to
immediately prevent a consequent pulse of treatment application
upon detection of nerve response to the optical stimulation.
[0029] In certain embodiments, sensing unit 130 may comprise a
sensing element arranged to detect movements of respective organs
or tissues or other mechanical effects (e.g., a change in pressure)
in the target organs or tissues.
[0030] In certain embodiments, sensing the electrical signal
produced by nerves 80 in response to the optical stimulation by
stimulation element 125 may be used to indicate proximity of
treatment element 115 and/or the treated tissue volume 95 (and see
also tissue volumes 117 in FIG. 3D) to a nerve. Control unit 140
may be arranged to immediately stop the application of the
treatment in order to avoid damage to the nerves. In certain
embodiments, control unit 140 may be arranged to reduce the
treatment intensity below a tissue damage threshold while
electrical nerve signals are sensed, or modulate the treatment
intensity in inverse relation to the intensity of the sensed
electrical signals or modulate the treatment pulse repetition
rate.
[0031] In certain embodiments, treatment element 115 and
stimulation element 125 may be integrated within a single probe
105, e.g., an optical fiber or fibers bundle (see various
embodiments below). In certain embodiments, stimulation element 125
may be attached to treatment element 115 mechanically or
adhesively. In certain embodiments, the tips of treatment element
115 and stimulation element 125 may be configured to have a
specified spatial arrangement that enhances the safety features of
system 100, as explained below. For example, a tip of stimulation
element 125 may project a specified distance ahead or aside of
treatment element 115 to monitor tissue regions which are advanced
at.
[0032] In certain embodiments, treatment system 100 may further
comprise an electrical stimulation unit 150 arranged to
electrically stimulate nerves in tissue region 90 and/or treated
tissue 95 via an electrical stimulation element 155 such as a
stimulation electrode 155, in addition to the optical stimulation.
Sensing unit 130 may be further arranged to sense an electrical
signal produced by nerves in the tissue and guided along the nerves
in response to the electrical stimulation. Stimulation electrode
155 may be attached to or integrated in treatment element 115 (see
FIGS. 5A-5E below) or in optical stimulation element 125. In
certain embodiments, electrical stimulation element 155 may be
configured to stimulate a larger tissue volume than optical
stimulation element 125, in order to provide long range alerts
regarding the presence of nerve in the vicinity of treatment region
95 (not necessarily in the immediate treatment region 117, see
below) to avoid iatrogenic nerve damage like overstretching and
clamping and/or to provide an overview of the nerves in the larger
area. Electrical stimulation element 155 may be associated with
treatment element 115 and be configured to stimulate respective
nerves to double-check optical stimulation sensing results, or for
any other medical purpose. Electrical stimulation unit 150 may be
arranged to stimulate nerves in a larger tissue volume 157 than
optically stimulated tissue volume 127 (see FIG. 3D). For example,
the electrical stimulation distance may be configured to be several
millimeters or several centimeters while the optical stimulation
may be configured to be in a range of tens or hundreds micrometers.
Control unit 140 may be arranged to provide an alert upon the
sensing of the electrical signal in response to the electrical
stimulation and/or to reconfigure treatment parameters upon the
sensing of the electrical signal in response to the electrical
stimulation.
[0033] In certain embodiments, the treatment is light-based, and
optical stimulation element 125 is configured to operate at a
wavelength range that has a higher penetration coefficient in the
treated tissue than a wavelength range in which optical treatment
element 115 operates. In certain embodiments, the wavelength range
in which optical stimulation element 125 operates is adjustable.
Optical stimulation element 125 may be configured to have a larger
incidence spot size than optical treatment element 115 in order to
enclose treated tissue volume 117 within stimulated tissue volume
127. Treatment element 115 may be an ablative cold laser and
optical stimulation element 125 may be a non-ablative laser.
Treatment element 115 and optical stimulation element 125 may be
lasers which are delivered through a single fiber, different fiber
cores in a single fiber and/or different fibers; and differ in at
least one of: their respective wavelength ranges, their respective
incident spot sizes, their respective tissue penetration
coefficient and their respective numerical apertures.
[0034] In certain embodiments, treatment element 115 may comprise
an ablative laser, e.g., in a wavelength ranges of 1.4-1.55 .mu.m
or 1.85-2.5 .mu.m or 9.6-11 .mu.m as non-limiting examples (see
FIGS. 2A-2D below). In certain embodiments, stimulation element 125
may comprise a laser configured not to ablate tissue, e.g., in a
wavelength ranges of 1.35-1.55 .mu.m or 1.85-2.5 .mu.m or 9.6-11
.mu.m as non-limiting examples or any other wavelength that
provides the required safety margin with respect to the treated
volume. In certain embodiments, treatment element 115 comprises a
cold laser.
[0035] FIGS. 2A-2D are illustrations of absorption and penetration
of electromagnetic radiation with respect to water, fat and blood
as proxies for the absorption and penetration of electromagnetic
radiation into tissue. FIG. 2A illustrates penetration and
absorption through water (note that penetration and absorption are
reciprocal), FIGS. 2B and 2C are illustrations of the absorption of
electromagnetic radiation of various tissue and blood components,
that may be used to adapt treatment and stimulation wavelength
ranges with respect to specific treatment regions 95. FIGS. 2B and
2C illustrate absorption by water (H.sub.2O, similar to FIG. 2A),
fat, hemoglobin (Hb), oxidized hemoglobin (HbO.sub.2), and mixed
oxidized and non-oxidized hemoglobin (Hb and HbO.sub.2 mixed) at
two wavelength ranges (0.2-2.2 .mu.m and 0.1-12 .mu.m,
respectively). FIG. 2D illustrates the dependency of the absorption
coefficient in water for a wavelengths between 9-11 .mu.m. FIG. 2D
is depicted in a linear scale (compare to FIG. 2C) in order to
illustrate the wavelength dependency of the absorption coefficient
which is utilized to achieve stimulation volumes 127 which are
larger than ablation volumes 117 (see FIG. 3D).
[0036] As is clear from FIGS. 2A-2D, the wavelength of the ablative
laser may be selected to have high absorption of radiation, while
the wavelength of the stimulation laser may be selected to have
higher penetration. For example, the wavelength of the ablative
laser may be selected as 1.94 .mu.m and the wavelength of the
stimulation laser may be selected as 2.1 .mu.m. This example is
non-limiting, as the specific wavelengths may be selected with
respect to specific treatment requirements and stimulation
requirements, and may even be dynamically changed during the
treatment. Advantageously, such selection combines effective small
volume ablation by treatment element 115 (requiring a high
absorption coefficient) with an effective larger stimulation volume
by stimulation element 125 (requiring a higher penetration
coefficient). The wavelengths may be adjusted to control the
spatial extent of the treatment, the spatial extent of the
stimulation, and the ratio of treatment to stimulation spatial
extents. The wavelengths may be selected with respect to
experimental data relating to specified tissues.
[0037] FIG. 3A is a schematic high level illustration of a
treatment signal 116 delivered by treatment element 115 such as an
ablative laser, an optical stimulation signal 126 delivered by
stimulation element 125 such as a non-ablative laser and a sensing
signal 136 as sensed by sensing electrode 135, according to some
embodiments of the invention. Signals 116, 126 and 136 are
illustrated with a common time scale. Upon detection of electrical
signal 134 in sensing signal 136 (e.g., resulting from the
preceding stimulation signal 126, in the non-limiting illustrated
case, a pulse), treatment signal 116 may be not applied (e.g., in
the non-limiting illustrated case, a next scheduled pulse may be
cancelled 146) to avoid damage to the stimulated nerves. In certain
embodiments, the treatment signal 116 may be resumed when no
electrical signal 134 is detected. Optical stimulation signal 126
may be delivered continuously during the treatment (e.g., as a
continuous train of pulses) in order to monitor the proximity of
treatment element 115 and/or treated tissue 95 to nerves 80, so
that sensing signal 136 may be monitored continuously. Sensing
signal 136 may be time correlated with stimulation signal 126 to
enhance the signal to noise and improve the nerve detection
reliability. In certain embodiments, stimulation signal 126 may be
arranged to precede treatment signal 116 by a time period that
enables cancelling 146 of the consecutive treatment signal 116 in
case of nerve detection.
[0038] In certain embodiments, treatment signal 116 (e.g., an
ablation pulse) may be selected to be shorter than 200 nanoseconds
(and may then be regarded as being "cold", i.e., as not heating the
tissue excessively) or to be several hundred .mu.s long, as in
common surgical lasers which heat the treated tissue to some extent
(in addition to the applied ablation effect). The pulse width
depends on the laser wavelength, the pulse energy, spot size, etc.,
and may be configured to enable efficient treatment effectively
controlled by the closed loop control circuit involving the optical
stimulation.
[0039] In certain embodiments, the pulse width of stimulation
signal 126 may be configured according to specific treatment
regions and profiles and may be flexibly configured during
operation with respect to the application of treatment signal 116.
The pulse fluence (energy/cm.sup.2) may selected to be below the
thermal damage threshold (few Joules/cm.sup.2) and the pulse width
may be selected to be shorter than the thermal relaxation time to
avoid heat dissipation. Practically, the pulse width of stimulation
signal 126 may be selected to be several hundred .mu.s or a few
milliseconds long. The period between treatment signal 116 and
stimulation signal 126 is selected to enable efficient detection of
detection signal 134 with respect to the nerve conduction velocity
and the distance of sensing electrode 135 from the stimulation
point.
[0040] It is noted that the time period between stimulation pulses
126 and treatment pulses 116 may be selected to accommodate the
time required for the nerves to respond (depending on nerve type
and location of electrode 135). In certain embodiments, stimulation
signal 126 and/or treatment signal 116 may be pulsed, with
stimulation pulses preceding treatment pulses. For example, the
pulse frequency may be 400 Hz, 10 Hz, 1 Hz. In certain embodiments,
stimulation signal 126 may comprise a single pulse or be in any
range between a very low frequency (<<1 Hz) and the limit of
nerve response (several tens of Hz or a few hundred Hz). The
stimulation frequency may be selected according to respective
stimulated nerves characteristics like refractoriness and
conduction speeds (e.g., in the range 0.5-120 meters per second,
or, depending on the nerve type. 0.5-3 m/s, 3-30 m/s, 30-80 m/s,
80-120 m/s) and with respect to the distance of sensing electrode
135 from treatment location 95 (e.g., few millimeters in case of
close electrode positioning, several centimeters in case of farther
electrode locations and up to tens of centimeters in case of
sensing electrodes positioned remotely from the location of
stimulation). The nerve diameters which are associated with each
conduction speed range may also be taken into account when
selecting the temporal pattern of the optical stimulation and
optical stimulation volume 127. Table 1 exemplifies a non-limiting
relation between an arithmetic limit of the optical stimulation
rate due to the nerve conduction speed and the location of sensing
electrode 135, which is derived from simple speed versus distance
consideration. For nerves with high conduction speed the actual
stimulation rate may be limited by the absolute refractory
period.
TABLE-US-00001 TABLE 1 An exemplary relation between an arithmetic
limit of optical stimulation rate, the nerve conduction speed and
the location of the sensing electrode. Nerve Conduction speed 0.5
m/s 120 m/s Arithmetic Arithmetic Distance to Excitation limit of
Excitation limit of sensing travelling Stimulation travelling
Stimulation electrode time rate time rate 5 cm 100 ms 10 Hz 417
.mu.s 2.4 kHz 10 cm 200 ms 5 Hz 834 .mu.s 1.2 kHz 15 cm 300 ms 3.3
Hz 1.25 ms 800 Hz
[0041] In certain embodiments, several stimulations may be
performed in each location to enhance the signal to noise ratio and
to differentiate between the stimulated action potential from the
sporadic/parasitic/spontaneous action potentials.
[0042] In certain embodiments, stimulation signal 126 may be
delivered at specified locations with respect to a pulse train of
treatment signal 116, or be itself delivered as a pulse train with
a frequency determined with respect to the treatment pulse train. A
ratio between the number of stimulation pulses 126 and treatment
pulses 116 may be selected with respect to nerve density in tissue
region 90 and/or with respect to other anatomical parameters and/or
with respect to the ratio between the treatment pulse penetration
volume and stimulation pulse penetration volume, ahead of treatment
or during treatment, with respect to the distance of the treatment
area to the nerve and may be adjustably configured in realtime.
Optical stimulation signal 126 may be adapted and adjusted in
realtime with respect to results of the electrical stimulation.
[0043] In certain embodiments, particularly ones in which nerves
having a low conduction speed are stimulated, the measuring
distance may be kept small by using noncontact electrophysiological
sensor(s) based on either electrical field sensing (like for
example, capacitive coupled electrodes) or magnetic field sensing
(like for example SQUID sensor(s)) as sensing electrode 135 or
remote sensor 135 (see FIG. 5E). In such application, sensing the
stimulated action potential may be carried remotely by non-contact
sensor 135 that may be attached to treatment element 115, to
stimulation element 125 or be placed independently of these
elements.
[0044] FIGS. 3B and 3C are high level schematic flowcharts
illustrating optical and optionally electric stimulation in a
closed loop control of a treatment tool, according to some
embodiments of the invention. In certain embodiments, optical
stimulation may be used for controlling the treatment tool in a
closed loop 114. FIGS. 3B and 3C illustrate optical treatment as a
non-limiting example; similar principles may be applied to other
types of treatment elements 115. Closed control loop 114 comprises
optical stimulation pulse 126 followed by a measurement of
resulting action potential(s) 136A. In case no signal (i.e., no
stimulation) has been detected, ablation pulse(s) 116C, 116D may be
applied (e.g., a train of Y pulses 116C, Y selected for the actual
ablation to be well within stimulation volume 127--FIG. 3B, or a
treatment pulse 116D of any kind which is contained within
stimulation volume 127--FIG. 3C). In case a signal (i.e.,
stimulation) has been detected, ablation may be prevented 146 as a
safety mechanism, implementing a "safe knife" configuration of the
ablative tool (treatment element 115). The practitioner may move
the tip of treatment element 115 to a safer location, as indicated
by lack of stimulation (i.e., ablated tissue volume 117 does not
include a target nerve). Closed loop 114 may be implemented without
manual intervention, allowing it to be fast and limited only by the
respective nerve response rate.
[0045] The control algorithm may be applied with respect to several
sensing elements 135, and with respect to their specific locations.
Calculations of required response time may also be differentiated
with respect to several sensing elements 135.
[0046] Optional electric stimulation may be implemented in addition
to the optical stimulation and may be used to check for nerves
within a larger region 157 than optical stimulation volume 127.
Advantageously, such bulk stimulation 156 may be used to map nerves
which are further away from the treatment location as an indication
of tissue being approached by treatment element 115 but is
currently not treated. Upon electric stimulation 156, action
potentials are measured 136B.
[0047] In case no signal (i.e., no stimulation) has been detected,
ablation pulse(s) 116A may be applied (e.g., a train of X pulses
116A, X selected with respect to the geometrical relations among
volumes 117, 127, 157--FIG. 3B) and/or a pulse counter may be reset
116F, and X pulses may be applied one by one upon no signal
detection following optical stimulation (FIG. 3C) or ablation
pulses may be applied as by the surgeon decision.
[0048] In case a signal (i.e., stimulation) has been detected as
result of the electric stimulation, either treatment may be
modified (e.g., into X pulses of careful ablation 116B, i.e.,
having lower energy, slower treatment rate, delay the next
pulse--FIGS. 3B, 3C) or an alert 116E may be created and ablation
continued only upon lack of signal detection after optical
stimulation 126 (FIG. 3C).
[0049] In certain embodiments (FIG. 3C), upon measuring action
potential 136A, a treatment pulse is avoided 146A, and alert 116G
is created and delivered to the surgeon, and treatment parameters
may be adapted or the next treatment pulse may be delayed 146B.
Upon surgeon's decision 147, further treatment parameters and
treatment location may be modified. The changes in treatment
parameters may be determined with respect to treatment type and
location, and take into account the refractory period of the
respective nerves.
[0050] In certain embodiments, electric stimulation 156 may be
manually triggered 154 in addition or in place of scheduled
electric stimulation.
[0051] FIG. 3D schematically illustrates tissue volumes 117, 127,
157 which are affected, respectively, by treatment and stimulation
elements 115, 125, 155 (respectively), according to some
embodiments of the invention. In certain embodiments, optically
stimulated tissue volume 127 (e.g., per laser pulse 126) at least
overlaps ablation volume 117 (e.g., per laser ablation pulse 146).
In certain embodiments, optical stimulation volume 127 per laser
pulse is larger than ablation volume 117 per laser treatment pulse
to ensure safety margins. Volume size adjustment may be achieved
using different wavelengths for stimulation element 125 and
treatment element 115 which are selected such that the penetration
depth of stimulation signal 126 (e.g., stimulation pulse) is larger
than the penetration depth of treatment signal 116 (e.g., ablation
pulse). In certain embodiments, electrically stimulated tissue
volume 157 may be much larger than optically stimulated tissue
volume 127.
[0052] The size of the safety margin may be controlled by the
difference of the tissue absorption coefficients of the two
wavelengths. In general, ablation volume 117 may be characterized
by a depth d.sub.1 and volume v.sub.1 which are determined by
wavelength .lamda..sub.1 and numerical aperture .psi..sub.1 as well
as by the spot size on the tissue (derived e.g., from the fiber
diameter and the distance to the tissue) while optical stimulation
volume 127 may be characterized by a depth d.sub.2 and volume
v.sub.2 which are determined by wavelength .lamda..sub.2 and
numerical aperture .psi..sub.2, as well as by the spot size on the
tissue (which may be different than for the treated volume).
Without being bound by theory, the scattering coefficient also
affects the respective volume. The scattering coefficient which is
wavelength dependent and the entrance spot size, in addition to the
numerical aperture, affect not only the volume width but also the
volume depth d. Therefore, two fibers with different core diameters
or using a concentric dual core optical fiber in which the ablation
laser propagates in the inner core and the stimulation propagates
in the inner and external cores can result in the required
differentiation between volumes 117, 127. These and other
parameters may be selected so as to provide a safety margin for the
operator of treatment element 115 and spare nerves in the operation
scene. Table 2 presents non-limiting examples for approximate
optically stimulated tissues volumes with respect to the selected
wavelength and the spot size on the tissue. The presented
approximation is geometrical and disregards optical effects which
may be taken into account in more detailed calculations. Thus, the
optical stimulation wavelength may be selected to provide a
stimulated tissue volume which provides sufficient safety margins
with respect to the treated tissue volume (which may be calculated
in a similar manner from the absorption curves--see e.g., FIG.
2A).
TABLE-US-00002 TABLE 2 An exemplary determination of approximate
optically stimulated tissue volumes with respect to the selected
wavelength and fiber aperture. Penetration Spot size on the tissue
Wavelength depth in water 50 .mu.m 100 .mu.m 250 .mu.m 1.875 .mu.m
222 .mu.m 0.44 10.sup.6(.mu.m).sup.3 1.74 10.sup.6(.mu.m).sup.3
10.88 10.sup.6(.mu.m).sup.3 2.22 .mu.m 630 .mu.m 1.24
10.sup.6(.mu.m).sup.3 4.94 10.sup.6(.mu.m).sup.3 30.88
10.sup.6(.mu.m).sup.3 2.30 .mu.m 435 .mu.m 0.85
10.sup.6(.mu.m).sup.3 3.41 10.sup.6(.mu.m).sup.3 21.31
10.sup.6(.mu.m).sup.3
[0053] The safety margin may be defined per specific applications
by pre-definition of the laser's wavelengths and/or fiber aperture
and/or numerical aperture. For example, in neuro-oncology surgery
where oncology safety is crucial the safety margin may be selected
to be low (e.g., 100 .mu.m around treatment region 117). In
contrast, in orthopedic surgery, where the nerve bundle is large
and visually recognized the safety margin may be selected to be
higher (e.g., 500 .mu.m around treatment region 117).
[0054] In certain embodiments, at least one of stimulation element
125 and treatment element 115 are tunable to enable adjustment of
the safety margins for specific applications (see the effect of
changing the wavelength on the stimulation volume in Table 2). This
safety margins may be planned to withstand ablation laser
variations such as pulse energy, pulse width etc. In certain
embodiments, the wavelength of the stimulation (.lamda..sub.2) may
be adjusted to control the size of the stimulation volume (v.sub.2)
over the tissue penetration coefficient (see FIGS. 2A, 2B). In
certain embodiments, elements 115 and/or 125 may be configured to
have specific spatial relationships that further define volumes
v.sub.1, v.sub.2.
[0055] For example, different treatment volumes v.sub.1 associated
with different common lasers are presented in Table 3. By adapting
wavelength .lamda..sub.2 of stimulation signal 126 according to
known penetration characteristics (e.g., FIGS. 2A, 2B), the
stimulated volume may be adjusted. The illustrated range of beam
widths (d.sub.1=50 .mu.m to 1 mm) is applicable to the beam widths
(d.sub.2) of stimulation signal 126 as well (beam width being
considered e.g. as the diameter that includes two thirds of the
beam energy). Penetration coefficients of stimulation signal 126
may be adjusted e.g., in a .mu..sub.a range of 10-1000 l/cm.
TABLE-US-00003 TABLE 3 Treatment volume for common laser types
Penetration Type of Wavelength coefficient Penetration Treatment
volume v.sub.1 (.mu.m).sup.3 laser .lamda..sub.1 (.mu.m) .mu..sub.a
(1/cm) depth (.mu.m) d.sub.1 = 50 .mu.m d.sub.1 = 1 mm Holmium 2.1
26 385 7.55 10.sup.5 3.02 10.sup.8 Thulium 1.94 114 88 1.72
10.sup.5 6.89 10.sup.7 fiber laser Thulium 2.01 62 161 3.17
10.sup.5 1.27 10.sup.8 solid state CO.sub.2 10.6 890 11 2.21
10.sup.4 8.82 10.sup.6
[0056] In certain embodiments, the safety margins may be tuned to
withstand the tool manual or robotic movement during the time
period between stimulation and ablation pulses (126 and 116
respectively). In applications of fast repetition rate treatment
laser, such as, for example, femtosecond laser as treatment element
115, stimulation signal 126 may be emitted every plurality of
femtosecond pulses to allow sufficient time for the nerves to
respond to the stimulation (nerve stimulation rates typically range
up to a few tens or hundreds Hz) and enable both effective ablation
by the femtosecond laser and maintaining the required safety
margin.
[0057] In certain embodiments, the two volumes (stimulation and
treatment volumes 127, 117, respectively) may be spatially adjusted
to compensate for movements or expected movements of treatment
element 115. In certain embodiments, treatment and stimulation
elements 115, 125 may have the same wavelength or the same
penetration coefficient and the safety margin may be defined by
setting of the operation parameters of any of elements 115, 125
(e.g., the ablation laser and/or the stimulation laser).
[0058] In certain embodiments, sensing element 135 may be
configured to sense excitation of certain nerves and not others.
Differentiation between nerves may be carried out anatomically, via
stimulation parameters and/or via sensing parameters. Treatment
aims may determine which nerves are sensed. In prostatectomy, for
example, nerves that innervate the prostate itself, which is to be
removed during the operation, may be severed, while nerve that
should function normally after the operation may be preserved.
Nerve identification may be carried out anatomically by placing
electrode 135 on the appropriate nerve(s) (or on nerves of target
organs) and not on nerves which are allowed to be severed. Nerve
identification may be carried out using nerve mapping (e.g.,
electrically) prior or during the operation. Nerve differentiation
may be carried out by adapting the stimulation efficiency, e.g.,
with respect to nerve structure (e.g., myelinated and
non-myelinated nerves may be stimulated differently, bundled and
non-bundled nerves may be stimulated differently, nerves in close
proximity of blood vessels may be stimulated differently than other
nerves). As an example for nerve differentiation by optical
stimulation, Wells et al. ("Pulsed laser versus electrical energy
for peripheral nerve stimulation", Journal of Neuroscience Methods
163 (2007) 326-337) demonstrate the validity of optical nerve
stimulation. In certain embodiments, differences in the dependency
of the penetration coefficients on the wavelengths (FIG. 2B) may be
used to determined stimulation volume v.sub.2 with respect to
different types of tissue and to different types of nerves. Based
on Wells et al.'s data, system 100 may be configured to have an
effective nerve stimulation beyond the treated volume (see, e.g.,
the penetration depth data in FIG. 8 in Wells et al.).
[0059] Advantageously, the proposed systems, devices and methods
overcome the common risk of nerve damage in many surgical
procedures. Damage to nerves of the central or peripheral nervous
systems harms the patient quality of life and may cause temporary
or permanent palsy or sensing inability. The known methods map
nerve structures electrically, and, therefore, they are limited by
the coarse localization nature of electric measurements and are
restricted to delayed sensing due to the noise of the stimulation
pulse. Therefore, known methods do not implemented a closed loop
control. The optical stimulation and laser based treatment
disclosed herein, localize the stimulation and treatment to the
penetration volumes and brings the resolution to sub-millimeter
ranges. This high resolution optical stimulation enables immediate
sensing without a time delay. This in turn enables real time closed
loop control of treatment application by the sensing measurements
of nerve excitation. The continuous measurement that is achieved in
the present invention which its measurement rate is limited by the
tissue response (mainly by the refractoriness) reflects the
effectiveness of high resolution optical stimulation and provides a
significant advantage with respect to known open loop electrical
stimulation based applications which measures manually from time to
time along the operation and includes the surgeon in the control
loop via a visual or auditory signal. The described systems and
methods may be applied to a wide variety of surgical procedures,
for example, surgical cutting, tissue ablation, excision and
coagulation and enhance the treatment safety by avoiding nerves
damage. In certain embodiments, the present invention teaches nerve
detection by laser nerve stimulation accompanied by electrical
detection of electrophysiological signals. Treatment system 100 may
be used with respect to various treatment tools and technologies
which may be implemented by treatment unit 110, such as
radiofrequency electromagnetic radiation (RF) or microwave
radiation (e.g., cutting devices; mono-polar, unipolar, bipolar
RF), mechanical procedures (cold cutting, e.g., by scalpel or
scissors), electro-optical treatment (e.g., lasers in various
operation modes--pulsed or continuous, laser in flash vaporization
mode, a femto-second laser etc.), plasma treatment, electrocautery
(electrical heat treatment), ultrasound (e.g., cutting tools) and
so forth. System 100 may be arranged to avoid mechanical injuries,
heat injuries etc. by appropriate tuning of sensing and damage
thresholds of sensing unit 130 and control unit 140,
respectively.
[0060] For example, the following are possible non-limiting
examples for medical applications for the proposed systems and
methods. In ear, nose, and throat (ENT) medicine, e.g., vocal cords
cancer, laryngology, facial surgeries, carotid endarterectomy and
carotid surgery in general, cricopharyngeal myotomy, excision of
Zenker's diverticulum, hemithyroidectomy, neck biopsy, neck
dissection, parathyroidectomy, partial laryngectomy, substernal
goiter, thyroidectomy and thyroid surgery in general, basal cell
cancer in the ear canal, melanoma in the ear canal, adenoid cystic,
adenocarcinoma, acoustic neuroma, parotid surgery etc. In urology,
e.g., benign prostatic hyperplasia (BPH), prostate cancer--radical
prostatectomy, bladder cancer, peyronie, perineal anal plastic
during paedriatric surgery, etc. In neurosurgery--accurate tissue
incision and avoiding damaging to the nerves in the central nervous
system, functional neurosurgery. In orthopedics--scoliosis, screw
placement during placement of opened and/or percutaneous pedicle
screw, minimal invasive surgery of intervertebral discs and general
orthopedics surgeries. Additional applications are in the fields of
heart thoracic surgery, mediastinoscopy, vascular surgery,
thoracoabdominal aorta aneurysm surgery, pain treatment procedures,
recognition of nerves in general surgeries and any other procedure
that may benefit from avoiding damage to the nerves in the
peripheral nervous system.
[0061] FIGS. 4A-4E are high level schematic illustrations of
element configurations, according to some embodiments of the
invention. FIG. 4A illustrates certain embodiments, in which the
ablative laser as treatment element 115 and the non-ablative laser
as stimulation element 125 are delivered through a single fiber
105. For example, elements 115, 125 may be arranged concentrically,
with stimulation element 125 comprising both layers (inner and
outer core) or one layer (e.g., the outer core) while treatment
element 115 comprises the inner core. In another example,
illustrated in FIG. 4B, elements 115, 125 may be the same fiber
105, with respective illumination 115, 125 directed into fiber or a
waveguide, e.g., via a beam combiner 102. Treatment element 115 and
simulation element 125 thus share an optical path through fiber 105
and have a same or a similar numerical aperture .psi., and beam
spread 103.
[0062] In certain embodiments, the ablative laser as treatment
element 115 and the non-ablative laser as stimulation element 125
are delivered through different fiber cores, or through separate
fibers or waveguides which are arranged to have the same numerical
aperture .psi. and/or same field of view (see angles .psi.) and/or
same beam spread 103. An optical element (not shown) may be
associated with any or both signals 116, 126. In certain
embodiments, stimulation volume 127 overlaps and encloses treatment
volume 117 and comprises additional appropriate safety margin,
illustrated in FIG. 4C. FIGS. 4D and 4E schematically illustrate
embodiments with separate treatment and stimulation elements 115,
125 (respectively), which may be implemented as single fiber device
105. Treatment and stimulation elements 115, 125 may have similar
or varying numerical apertures and beam spreads 103. In certain
embodiments any of the parameters numerical apertures .psi.,
diameters d, wavelength ranges .lamda., aperture diameter d may
vary between treatment and stimulation elements 115, 125 to
determine treatment and stimulation volumes 117, 127 under given
circumstances or treatments.
[0063] FIGS. 5A-5E are high level schematic illustrations of
configurations of treatment fiber 105, with treatment element 115
and stimulation element 125, optional electric stimulation element
155 and sensing electrode 135, according to some embodiments of the
invention. Any type of electrode arrangement (e.g., dipolar
configuration, unipolar configuration, etc.) may be used for
sensing electrode 135 and/or electric stimulation element 155. In
the present figures, sensing electrode 135 and optional electric
stimulation element 155 comprise, in a non-limiting example, two
electrodes 135A, 135B and 155A, 155B, respectively.
[0064] In certain embodiments, sensing electrode 135A may be
attached to or integrated in single fiber 105. In certain
embodiments, sensing electrode 135A may be attached downstream of
the relevant nerves 80. For example, FIG. 5A schematically
illustrates sensing electrode 135A attached to fiber 105 (or to
treatment element 115), having optical stimulation element 125
which is also attached to fiber 105. In certain embodiments,
optional electrical stimulation electrode 155A may be attached to
fiber 105 (or to treatment element 115) similarly to the connection
of sensing electrode 135A. A second sensing and/or electric
stimulation electrode 135B and/or 155B (respectively) may be
attached to fiber 105 at a certain distance from electrode 135A
and/or 155B (respectively).
[0065] In another example, FIG. 5B schematically illustrates
sensing electrode 135A positioned in tissue region 90 (e.g., on the
penis in case of a prostate related procedure, see FIG. 1A, at the
back region or on a leg in an exemplary microsurgery in at the back
region, see FIG. 1B), fiber 105 having optical stimulation element
125 as the same fiber as treatment element 115 or as a separate
fiber attached thereto. In certain embodiments, fiber 105 may
deliver both treatment and stimulation optical signals (116, 126
and treatment and stimulation elements 125 respectively) and
electric stimulation electrode 155A may deliver an electrical
stimulation signal 156 (with respect to second electric stimulation
electrode 155B).
[0066] FIG. 5C schematically illustrates sensing electrode 135B
and/or optional electric stimulation electrode 155B as concentric
elements with treatment and/or optical stimulation elements 115,
125 respectively, for example within a common jacket 104.
Optionally, additional electrical stimulation may be delivered via
a concentric electrode 155 with fiber 105 delivering optical
stimulation (as stimulation element 125) in addition to the
treatment delivered by separate treatment element 115. Sensing
electrode 135 may be attached separately to tissue region 90.
Clearly, both stimulation element 125 and sensing electrode 135 may
be implemented within jacket 104 or attached thereto, either or
both concentrically with treatment element 115.
[0067] FIG. 5D schematically illustrates sensing electrode(s) 135
and/or optional electric stimulation electrode(s) 155 as enclosing
treatment element 115 and/or optical stimulation element 125. In
such configurations, probe 105 may be used to combine electric
stimulation, optical stimulation and actual treatment. Electrode
135 and/or 155 may be configured as a single electrode (B) with or
without a second electrode (A) at a tissue target, or electrode 135
and/or 155 may be implemented to comprise two (or more) electrodes
(A and B) within the single tip, implementing e.g. a bipolar
configuration. An advantage of a configuration having a rounded tip
is that it ensures continuous contact with the tissue during the
stimulation while enabling smooth tool movement.
[0068] FIG. 5E schematically illustrates probe 105 having a remote
electric sensing element 135. Remote electric sensor 135 may be
positioned at the tip of probe 105 and be operated by sensor
electronic 139 connected via electric wire 138 to a power source
and sensing unit 130. In certain embodiments, remote sensor 135 may
be arranged to sense magnetic fields. In certain embodiments,
non-contact sensor 135 may be arranged to sense any of a
radiofrequency (RF) signal, an electric field and a magnetic
field.
[0069] In certain embodiments, treatment element 115 and optical
stimulation element 125 may be implemented as one or more optical
fibers that are applied laparoscopically (manually and/or
robotically). Treatment element 115 and stimulation element 125 may
be implemented as different fiber cores, or as separate waveguides
or fibers, and may have a common field of view or cover volumes
such that stimulation volume 127 encloses treatment volume 117
(see, e.g., FIG. 3B). Sensing element 135 may, in some embodiments,
be implemented remotely, i.e. as respective antennas which are not
in direct contact with the location from which sensing measurements
are taken and/or the location which is electrically excited
(respectively).
[0070] In certain embodiments, electric stimulation element 155 may
apply electrical stimulation, not necessarily simultaneously with
treatment element 115 and/or optical stimulation element 125.
Electrical nerve stimulation may be used to coarsely localize the
neural structures while the optical nerve stimulation may be used
for high resolution nerve localization. In certain embodiments,
sensing element 135 may be adapted to perform two types of
sensing--one relating to electrical excitation, and another
relating to optical excitation of nerves. In certain embodiments,
sensing unit 130 may be arranged to map nerves in the treatment
area as well as preventing nerve damage during treatment
application at a more local level. Control unit 140 may implement
decision making algorithms to control the treatment activation
(e.g., ablation and/or cutting) according to the received nerve
signals (136). In both types of stimulation, sensing results may be
used to test function of the nerve structures to early detect
intraoperative injury, allowing for immediate corrective measures.
Either or both stimulation elements may be implemented in
association with treatment element 115 or separated therefrom,
relating though to stimulation volume 127 that encloses treatment
volume 117.
[0071] In certain embodiments, treatment system 100 may comprise
treatment unit 110 comprising optical fiber 115 arranged to apply a
cold laser ablative treatment to tissue 90 (or target 95 in tissue
90); optical stimulation unit 120 arranged to optically stimulate
nerves 80 in tissue 90, in close proximity to location 95 of
treatment application; electrical stimulation unit 150 arranged to
electrically stimulate nerves 80; sensing unit 130 comprising at
least one sensing electrode 135 arranged to sense an electrical
signal produced by nerves 80 in tissue 90 in response to the
optical stimulation, and to sense an electrical signal produced by
nerves 80 in tissue 90 in response to the electrical stimulation;
and control unit 140 arranged to control the optical stimulation
and the electrical stimulation and control the application of the
ablative treatment in realtime and in a closed loop according to
the sensed electrical signal produced by nerves in the tissue in
response to the optical stimulation. Control unit 140 may be
arranged to immediately prevent treatment application upon sensing,
by sensing unit 130, of the electrical signal produced by nerves in
the tissue in response to the optical stimulation, and to modulate
treatment application upon sensing, by sensing unit 130, of the
electrical signal produced by nerves in the tissue in response to
the electrical stimulation.
[0072] FIG. 6 is a high level schematic flowchart illustrating a
method 200 according to some embodiments of the invention. Method
200 may comprise configuring a tissue treatment system (stage 250)
to stimulate nerves in the tissue (stage 210), sense an electrical
signal produced by nerves in the tissue (stage 230) in response to
the stimulation and control the treatment according to the sensed
electrical signal (stage 240). In certain embodiments, the
treatment may be carried out by an ablative laser (stage 215) and
the stimulation may be carried out by a non-ablative laser (stage
220). A wavelength range of the non-ablative laser may be selected
to penetrate the tissue to a larger depth and width than the
wavelength range of the ablative laser. In certain embodiments, the
stimulation is carried out optically (stage 227) and optionally
additional stimulation may be carried out electrically (stage
225).
[0073] In certain embodiments, the sensing may be carried out in
the treated tissue (stage 232), for example within a specified
sensing volume. The treated tissue volume may be enclosed within
the stimulated tissue volume (stage 234). In certain embodiments,
the sensing may be carried out with respect to specified nerves
(stage 235), determined functionally, morphologically or
electrically. Furthermore, method 200 may comprise mapping nerves
in surrounding tissue and monitoring the mapped nerves in the
treatment area (stage 237).
[0074] In certain embodiments, method 200 may comprise carrying out
nerve preserving surgery procedures, such as nerve preserving tumor
removal (stage 260) and nerve-preserving prostatectomy (stage
270).
[0075] In certain embodiments, method 200 may comprise configuring
a tissue treatment system to optically stimulate nerves in the
tissue, sense an electrical signal produced by nerves in the tissue
in response to said optical stimulation and control the treatment
according to the sensed electrical signal. Method 200 may further
comprise immediately preventing treatment application upon sensing
the electrical signal produced by nerves in the tissue in response
to the optical stimulation. For example, method 200 may comprise
interspersing the optical nerve stimulation among pulses of
treatment application and immediately preventing a consequent pulse
of treatment application upon detection of nerve response to the
optical stimulation. The treatment may be optical and method 200
may further comprise configuring the optical stimulation and the
optical treatment to differ in at least one of: their respective
wavelength or wavelength ranges, their respective incident spot
sizes, their respective tissue penetration coefficient and their
respective numerical apertures. In certain embodiments, method 200
may comprise electrically stimulating nerves and sensing an
electrical signal produced by nerves in the tissue in response to
the electrical stimulation. The treated tissue volume may be
arranged to be enclosed within a stimulated tissue volume, and the
optically stimulated tissue volume may be arranged to be enclosed
within an electrically stimulated tissue volume. Method 200 may
further comprise providing an alert upon the sensing of the
electrical signal in response to the electrical stimulation and/or
reconfiguring treatment parameters upon the sensing of the
electrical signal in response to the electrical stimulation.
[0076] Advantageously, while current technologies enable crude
sensing of nerves, at a millimeter scale and prior to the actual
treatment or in an open loop and low sensing rate (e.g., using
stimulation and sensing electrodes which are mounted and removed
prior to the treatment, or are left on the patient and the
treatment interrupted at periods to carry out a measurement, or
involving the surgery team members in the loop using visual or
auditory signals), the current invention allows sensing of nerves
on a scale smaller than 1 mm, in realtime during the treatment, and
enable implementation of automatic, closed-loop control of the
treatment energy emission to avoid damage to nerves. The invention
is applicable to any treatment tool, particularly to laser
treatment tools. For example, the current invention may be applied
to nerve-preserving tumor removal treatment and be configured to
allow maximal tumor removal without damaging nerves adjacent to the
tumor.
[0077] Advantageously, with respect to known intraoperative
neurophysiological monitoring (IONM) techniques which comprise
electrical stimulation during operation for nerve monitoring,
optical stimulation has a significantly better signal to noise
ratio than the electrical stimulation, which enables faster
processing time leading to efficient real time implementation.
Optical stimulation is also much more localized than electric
stimulation, enabling finer and more exact nerve detection,
enabling to have the stimulation volume and the treatment volume at
the same order of magnitude, leading to high resolution and real
time controlled treatment. Combining long range coarse electric
stimulation with short range fine optical stimulation enables to
avoid both coarse damages (e.g., mechanical damages) and fine
damages (e.g., accidental ablation or cutting). Further use of cold
laser as the treatment elements provides an additional degree of
safety by avoiding thermal damage to nerves.
[0078] In the above description, an embodiment is an example or
implementation of the invention. The various appearances of "one
embodiment", "an embodiment", "certain embodiments" or "some
embodiments" do not necessarily all refer to the same
embodiments.
[0079] Although various features of the invention may be described
in the context of a single embodiment, the features may also be
provided separately or in any suitable combination. Conversely,
although the invention may be described herein in the context of
separate embodiments for clarity, the invention may also be
implemented in a single embodiment.
[0080] Certain embodiments of the invention may include features
from different embodiments disclosed above, and certain embodiments
may incorporate elements from other embodiments disclosed above.
The disclosure of elements of the invention in the context of a
specific embodiment is not to be taken as limiting their used in
the specific embodiment alone.
[0081] Furthermore, it is to be understood that the invention can
be carried out or practiced in various ways and that the invention
can be implemented in certain embodiments other than the ones
outlined in the description above.
[0082] The invention is not limited to those diagrams or to the
corresponding descriptions. For example, flow need not move through
each illustrated box or state, or in exactly the same order as
illustrated and described.
[0083] Meanings of technical and scientific terms used herein are
to be commonly understood as by one of ordinary skill in the art to
which the invention belongs, unless otherwise defined.
[0084] While the invention has been described with respect to a
limited number of embodiments, these should not be construed as
limitations on the scope of the invention, but rather as
exemplifications of some of the preferred embodiments. Other
possible variations, modifications, and applications are also
within the scope of the invention. Accordingly, the scope of the
invention should not be limited by what has thus far been
described, but by the appended claims and their legal
equivalents.
* * * * *