U.S. patent application number 14/685548 was filed with the patent office on 2017-02-23 for multiple electrode radiofrequency generator.
This patent application is currently assigned to COSMAN MEDICAL, INC.. The applicant listed for this patent is COSMAN MEDICAL, INC.. Invention is credited to Eric R. Cosman.
Application Number | 20170050038 14/685548 |
Document ID | / |
Family ID | 52782325 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170050038 |
Kind Code |
A1 |
Cosman; Eric R. ; et
al. |
February 23, 2017 |
MULTIPLE ELECTRODE RADIOFREQUENCY GENERATOR
Abstract
A method and apparatus for application of an electrical signal
to neural and other target tissue in the living body can include a
device connected to at least two electrodes, wherein temperature
sensors are incorporated into tip portions of said electrodes and a
a high frequency generator operatively associated with said
device.
Inventors: |
Cosman; Eric R.; (Belmont,
MA) ; Cosman; Eric R.; (Belmont, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COSMAN MEDICAL, INC. |
BURLINGTON |
MA |
US |
|
|
Assignee: |
COSMAN MEDICAL, INC.
BURLINGTON
MA
|
Family ID: |
52782325 |
Appl. No.: |
14/685548 |
Filed: |
April 13, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11872447 |
Oct 15, 2007 |
9008793 |
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14685548 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2018/00761
20130101; A61B 18/1206 20130101; A61B 2018/00767 20130101; A61B
2018/00434 20130101; A61N 1/36021 20130101; A61N 1/403 20130101;
A61B 2018/00702 20130101; A61B 2018/00839 20130101; A61B 2018/143
20130101; A61B 2018/00714 20130101; A61N 1/06 20130101; A61B 5/0488
20130101; A61B 2018/00797 20130101; A61B 2018/00654 20130101; A61B
5/4893 20130101; A61B 18/1477 20130101; A61B 2018/124 20130101 |
International
Class: |
A61N 1/40 20060101
A61N001/40 |
Claims
1. An apparatus for performing tissue modification procedures on a
patient's body, comprising: a device connected to at least two
electrodes, wherein temperature sensors are incorporated into tip
portions of said electrodes; a high frequency generator operatively
associated with said device, wherein said generator is configured
to deliver non-simultaneously a high frequency signal output to
each of said electrodes in a cyclical sequence so that no two
electrodes have said high-frequency signal output applied to them
at the same time; and a feedback control circuit configured to
regulate the signal output delivery to each of said electrodes so
as to maintain a user settable temperature at a tip portion of said
electrodes when the electrodes are in contact with the patient's
body based on temperature measurements from said temperature
sensors.
2-10. (canceled)
Description
TECHNICAL FIELD
[0001] The invention relates generally to field therapy.
BACKGROUND
[0002] The use of radiofrequency (RF) generators and electrodes in
neural tissue for the treatment of pain and functional disorders is
well known. Included herein by reference, an as an example, the
RFG-3C Plus RF Generator of Radionics, Inc., Burlington, Mass., and
its associated electrodes are used in the treatment of the nervous
system, and the treatment pain and functional disorders. This
device is capable of delivering high frequency energy to patient
tissue via an adapted electrode, and associated ground or reference
electrode. This device is also capable of delivering low frequency
stimulation pulses that are used to accurately localize the
electrode placement before treatment. This unit delivers high
frequency signal output both in a continuous RF mode and in a
pulsatory RF mode, referred to as pulsed RF (PRF). In continuous RF
mode, target tissue is heated near the uninsulated electrode tip of
the high frequency electrode by the application of a high frequency
signal output from the RF generator onto the tissue near the
uninsulated electrode tip. For example, in continuous RF mode, it
is common that a target tissue is heated in the range of 45 to
100.degree. C. to selectively destroy the target tissue by heating.
In the pulsed RF mode (PRF), intermittent bursts of high frequency
signal output are delivered by the RF generator and applied to
target tissue through the uninsulated electrode tip of the high
frequency electrode. This is typically used to treat pain
syndromes. The PRF signal output typically comprises a short period
of on-time of high frequency signal, for example 0.1 to 50
milliseconds of on-time, followed by a period of off-time which has
a duration that is substantially longer than the duration of the
on-time (for example, 100 to 1000 milliseconds) in which the signal
output is substantially lower than the signal output in the on-time
burst, for example, near or at 0. The bursts of high frequency
signal output are typically in the range of one to five bursts per
second, referred to as pulses per second (pps), or Hertz (Hz).
Because in PRF in the on-time period, signal output occurs for a
short period, the amount of tissue heating near the uninsulated
electrode tip of the high frequency electrode is reduced compared
to, continuous RF mode for the same magnitude of signal output.
[0003] The RFG-3C Plus generator has one electrode output jack for
connection to a single active electrode, and it has one reference
electrode jack for connection to a reference electrode. When the
active electrode is inserted into the body, and the reference
electrode is placed, typically on the patient's skin, then RF
current form the RF generate flows through the patient's body
between the two electrodes. The generator can be activated and its
signal output can be applied between the electrodes. Typically,
this is referred to as a monopolar configuration because the active
electrode is of smaller area than the reference electrode, and so
the concentration of RF current is highest near it and the action
of the RF electric field, whether for heating or for pulsed RF
field therapy is greater there. This usually referred to as a
single electrode configuration since there is only one "active"
electrode.
[0004] Parameters that can be measured by the RFG-3C Plus RF
generator include impedance, HF voltage, HF current, HF power, and
electrode tip temperature. Parameters that may be set by the user
include time of energy delivery, desired electrode temperature,
stimulation frequencies and durations, and level of stimulation
output. In general, electrode temperature is a parameter that may
be controlled by the regulation of high frequency output power.
Existing RF generators have interfaces that allow the selection of
one or more of these treatment parameters, as well as various
methods to display the parameters mentioned above.
[0005] In another example, the reference electrode can be inserted
into the patient's body, and it can have an active area that is
smaller and of comparable size to the active electrode. In that
case, both electrodes become "active" in the sense that both of the
have high temperature or electrical field effects on the tissues
around them, so that they are both involved actively in the
therapeutic effects the RF signal output. This can be referenced to
as a single "bipolar" configuration.
[0006] A limitation for the monopolar and the bipolar configuration
just described is that it limits the RF therapy to one or two
electrode locations, respectively. In same situations it is
desirable to treat more than one or two positions in the bodily
tissue, and thus desirable to have more electrodes involved as the
procedure goes on. For example, this can save time if there are
multiple sites to be treated, as for example, multiple levels of
the spinal medial branches to be treated for back pain.
[0007] The Untied Stated Patent Application Publication entitled
Method and Apparatus for Diagnosing and Treating Neural
Dysfunction, by W. J. Rittman, Pub. No. US 2007/0032835 A1, Pub.
Date: Feb. 8, 2007, describes an RF generator system comprising an
RF generator with multiple active electrode output connections that
enables the RF signal output the generator to be connected and
delivered simultaneously to more than one electrode to deliver a
therapeutic effect at each of the electrode positions at the same
time. The RF generator's signal output is switched by switches and
switch controllers so that the RF generator's output is applied to
multiple electrodes at the same time, that is, simultaneously. In
another aspect, the RF generator's switches and switch controllers
are independent, that is the switch and switch controller for one
of the electrodes performs independently from those of a second
electrode or from those of multiple individual electrodes. This has
one disadvantage that, because the signal output can be applied to
more than one electrode at the same time, the voltage of the
generator's power supply and output electronics can be loaded down
at the same time, causing sag or droop of the signal output voltage
during application. Another disadvantage is that the electrical
field from each of the electrodes adds coherently in the bodily
tissue, making it more difficult to separate their individual
effects on the bodily tissue. Another disadvantage is that it makes
it more difficult to control the RF signal output and to maintain
the RF signal output so as to maintain the temperatures of the
electrodes at a set temperature chosen by the user.
[0008] Examples of high frequency generators and electrodes are
given in the papers of entitled "Theoretical Aspects of
Radiofrequency Lesions and the Dorsal Root Entry Zone," by Cosman,
E. R., et al., Neurosurgery 15:945-950, 1984; and "Methods of
Making Nervous System Lesions," by Cosman, E. R. and Cosman, B. J.
in Wilkins R. H., Rengachary S. S. (eds): Neurosurgery, New York,
McGraw-Hill, Vol. III, pp. 2490-2498, 1984, and are hereby
incorporated by reference herein in their entirety.
[0009] Four patents have issued on PRF by Sluijter M. E., Rittman
W. J., and Cosman E. R. They are "Method and Apparatus for Altering
Neural Tissue Function," U.S. Pat. No. 5,983,141, issued Nov. 9,
1999; "Method and System for Neural Tissue Modification," U.S. Pat.
No. 6,161,048, issued Dec. 12, 2000; "Modulated High Frequency
Tissue Modification," U.S. Pat. No. 6,246,912 B1, issued Jun. 12,
2001; and "Method and Apparatus for Altering Neural Tissue
Function," U.S. Pat. No. 6,259,952 B1, issued Jul. 10, 2001. These
four patents are hereby incorporated by reference herein in their
entirety.
[0010] In one example of the use of RF generators, a patient may
complain of back pain, or some other pain of known or neuropathic
origin. A clinician will often perform diagnostic blocks with local
anesthetic by injecting the anesthetic into the areas that are
suspected of generating the pain. If the patient receives temporary
pain relief from these injections, the doctor concludes that the
anatomical positions of the origin sites of the pain are in the
locations where he made these injections. Unfortunately, the origin
of pain is poorly understood; perceived pain at a certain level in
the back, for instance, can actually be created from many different
and multiple sources and anatomical locations.
[0011] Once a location has been identified, the clinician will
decide to deliver high frequency signal output form a high
frequency generator to this location to permanently destroy the
source of the pain. A ground or reference plate will be placed on
the patient's thigh to provide a return path for the high frequency
energy. An insulated electrode with a small uninsulated tip will be
placed at the expected target location. Stimulation pulses will be
delivered at a sensory frequency (typically 50 Hz), and a
stimulation voltage signal output will be applied to the electrode.
The clinician is looking for a very low threshold of response from
the patient (e.g., less than 0.5 V) to ensure that the electrode is
close to the sensory nerves. They will then perform a stimulation
test at a muscle motor frequency (e.g., 2 Hz), and increase the
stimulation voltage output to 2 volts. In this instance, they are
looking for no motor response in the patient's extremities as this
would indicate the electrode was too close to the motor nerves.
Treatment in this area could cause paralysis. Upon successful
completion of these tests, high frequency energy is typically
delivered for one or more minutes, while maintaining an electrode
tip temperature between 70 and 90 degrees. Alternatively, high
frequency signal output can be delivered for one or more minutes,
but in a pulsed mode where the high frequency signal output is on
for a short period of on-time and off for a long period of
off-time, and thus the pulsed high frequency application will not
produce any appreciable heating (reference is made to sited patents
in the Background section herein)
[0012] Although these treatments are successful, they have several
drawbacks. In practice, most patients need treatments at several
different nerve locations. This requires placing the electrode,
performing the stimulation, and delivering the high frequency
signal output at each location, and then repeating the process.
This can cause a great deal of wasted time, and patient discomfort,
while waiting for the high frequency signal output to be delivered.
Another drawback is that, in spite of successful stimulation
testing; the target nerve is often not destroyed, thus resulting in
no decrease of pain. The clinician is left to determine whether the
target nerve has been missed, or whether the pain generator is
located elsewhere in the body.
SUMMARY
[0013] The present invention relates generally to the applications
of RF to multiple electrodes positioned in tissue of the living
body. In one example, an RF generator has connections to more that
one electrode so that therapeutic effects can be delivered to
multiple sites on the living body during the same treatment
session. An RF power source in the RF generator connects to the
individual electrodes through switches and controllers in a way
that the signal output of the RF generate is delivered
non-simultaneously to the electrodes. In one example, the switches
and the controllers for the individual electrodes are dependent on
each other to assure, for example, that the signal output of the
power source is only connected to one electrode at a time. In
another example, the controllers and switches are made dependent so
that the signal output of the generator is only connected to
bipolar pairs of the multiple electrodes at separate times, that
is, non-simultaneously. One advantage of this non-simultaneous
connection to the individual electrodes is that the signal output,
for example, the voltage of the power source, is only being
delivered to one electrode at a time, and thus the power source
will not be over-loaded and thus its signal output will not be
pulled down or sag. Another advantage is that, in one example,
since only one electrode is activated at a time, the therapeutic
agent, for example, heat or the electrical field is applied to the
target tissue separately in time slices. This has an advantage that
that the circuit controls for each electrode can be operated
separately in time from the circuit controllers of the other
electrodes. This has one advantage of simplifying the control
algorithm for overall control of the heating and overall time of
the treatment of the procedure. The generator can deliver
programmatically the high frequency signal output to each of said
electrodes and/or the generator can deliver sequentially the high
frequency signal output to each of said electrodes.
[0014] In one example, the signal output of the RF generate is
applied non-simultaneously in a cyclical time sequence that is
controlled by a master timing controller in the RF generator. One
advantage of that is the signal is applied in a smooth time
sequence. The time space can be divided into time bins or time
slices, each time slice being devoted to one electrode, and the
time slices repeat themselves in cyclical manner. The electrode
controllers synchronize the series of these time slices and thus
synchronize the delivery of the high frequency signal output
application to the multiple electrodes. One advantage of this is
that the control algorithm is separable in terms of the temperature
and the time bin slice for an individual electrode, making the
entire control of the multi-electrode application linear and
separable in time.
[0015] In one example, the dependent controllers are synchronized
with a common clock. During the on-time time slice for an
individual electrode, its controller will apply an amount of signal
output, for example, voltage, on that electrode with sufficient
amplitude, has governed by the controller, to elevate the
temperature or the electrical field at that electrode. In one
example, the controller can be connected to a temperature sensor in
the electrode so that the signal output level delivered to the
electrode as governed by the controller, is determined by
comparison of the measured temperature at the temperature sensor to
a set temperature decided upon or, in one example, by the operator.
In another example, during the time slice of one electrode, the
signal output level applied to the electrode can be delivered to
the electrode for a variable fractional time during the time slice,
so that the controller can drive, for example, the temperature or
the electric field at the electrode towards or away from some
target or set value or, in another example, towards a set value
that has been pre-set by the user or which is derived by a
feed-back algorithm programmed into the controller.
[0016] In another example, the time slices relate to individual
pairs of electrodes that are to be used in a bipolar configuration.
Bipolar pairs are activated during non-simultaneous times and by
dependent, coordinated controllers. One advantage of this is that
bipolar pairs of electrode can be activated separately and without
coherent interference from another pair of bipolar electrode
pairs.
[0017] Disadvantages of the prior art are overcome by the present
method and system which relate to delivering the signal output from
a high frequency generator non-simultaneously to more than one
treatment electrode that are involved in the clinical procedure. In
one example, the high frequency signal output is cyclically
sequenced to the multiple electrodes so that no two electrodes have
the high frequency signal output applied to them at the same time,
and the signal outputs to each electrode are regulated by a
feedback mechanism included in the system such that each
electrode's tip temperature is maintained to a level (set
temperature) set by the user. This greatly reduces treatment time,
providing the patient with a shorter period of discomfort as well
as not wasting valuable clinician and procedure-room time.
[0018] In one example, EMG measurements are displayed on the system
to allow the clinician to determine whether the target nerve has
been destroyed, as well as the display of pre-treatment and
post-treatment sensory stimulation thresholds to measure the degree
of desensitization of the target nerve. Measuring the EMG signals
allows the clinician to determine whether the target nerve has been
successfully treated. Comparison of pre-treatment and
post-treatment sensory stimulation thresholds gives the clinician
an immediate look at the desensitization of the target nerve.
[0019] In one example, the system can deliver at different times in
the procedure, both high frequency signal output as well as low
frequency stimulation pulses. The device can be, in turn, connected
to greater than one treatment electrode. These electrodes have
temperature sensors attached to their tips, which reports the tip
temperature of each electrode to the system. The system has a user
interface which allows the signal output from the system, in one
mode, to be connected independently and/or individually to each of
the multiple electrodes, and also, in another mode, to enable the
high frequency signal output from the system to be connected in
sequenced, non-simultaneous time-cycles to the multiple electrodes
that are connected by cables to the system. In this way, the
low-frequency stimulation signal output from the system can, in one
phase of the procedure, be independently connected to each of the
patient electrodes. Then, in another phase of the procedure, the
high frequency signal output from the system can be connected
non-simultaneously, and in a sequential manner that is controlled
by the system, to the multiple electrodes. Temperature regulation
of the temperature measured at the multiple electrodes can be
controlled by the system during the time that the high frequency
signal output is being applied in the heating phase of the
procedure. The system can provide the capability of both sensory
and motor stimulation testing, as well as impedance monitoring to
be performed on each of the multiple electrodes during the
procedure. When it is desired that the therapeutic high frequency
signal output is to be delivered, the user interface allows the
non-simultaneous, sequential connection the multiple electrodes to
be carried out by the system control electronics and feedback
algorithms. Tip temperatures from each of the multiple electrodes
can be readout and stored in the system, and a set temperature for
each electrode can be chosen by the user. The device can
continually compare each of the temperatures from the electrodes to
the set temperature. If the electrode tip temperature for an
individual electrode exceeds the set temperature, the high
frequency signal output to that electrode can be reduced during the
programmed time slice of activation of the high frequency signal
output to that electrode Similarly, if the electrode tip
temperature is less than the set temperature, the high frequency
signal output to that electrode can be increased by the system
control electronics.
[0020] In one example, a system graphic display, which allows EMG
and/or EEG signals to be recorded and displayed. In another
example, speaker and/or a headphone output allow the EMG and/or EEG
signals to be audibly detected and analyzed.
[0021] In one example, the present system and method can comprise a
high frequency power source that is integrally built into the
system. In another example, the system can comprise a stand-alone
peripheral device that can be connected between a high frequency
power source and the multiple electrodes.
[0022] In one example, the system and method of the present
invention can be applied to the nervous system for the treatment of
pain and/or functional neurological diseases such as Parkinson's
disease or mood disorders. In another example, the system and
method can be applied to treat cancerous tumors or other functional
disorders anywhere in the patient's body.
[0023] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
Claims.
DESCRIPTION OF DRAWINGS
[0024] In the drawings that constitute part of the specification,
embodiments exhibiting various forms and features hereof are set
forth, specifically:
[0025] FIG. 1 is a schematic diagram showing a high frequency
generator with four electrodes connected to it and a graphic
display.
[0026] FIG. 2 is a schematic diagram showing feedback and control
circuitry.
[0027] FIG. 3 is a schematic diagram showing a circuit block
elements for dependent control of three electrodes connection to a
high frequency generator with non-simultaneous energizing of the
electrodes.
[0028] FIG. 4 shows a schematic diagram of time slices with
non-simultaneous sequencing of electrode activation with respect to
a high frequency generator.
[0029] FIG. 5 shows a schematic diagram of cyclical sequencing of
time slices of electrode energizing with signal output amplitude
variations to enable feedback control of the high frequency
therapy.
[0030] FIG. 6 shows a schematic diagram of time-bin slices that are
cyclically sequenced so that the multiple electrodes are energized
separately in time, and the magnitude of the heating effect for a
given electrode is modulated by varying the percent of on-time of
the signal output during the time-bin slice for that electrode.
[0031] FIG. 7 shows a schematic block diagram of an electrical
circuit comprising a master timing and coordinating controller that
the controls the individual feed-back controllers of the individual
electrodes.
[0032] FIG. 8 shows a schematic diagram of a multi-electrode high
frequency electrode system comprising multiple pairs of bipolar
electrodes.
[0033] FIG. 9 is a schematic diagram showing a high frequency
generator with four electrodes connected to it and graphic
display.
[0034] FIG. 10 is a schematic diagram showing a high frequency
generator with EMG graphic display and multi electrode
connections.
[0035] FIG. 11 is a schematic diagram showing a high frequency
generator with four electrodes connections, graphic display, and
recording of stimulation testing thresholds.
[0036] FIG. 12 is a schematic diagram showing a high frequency
generate with multi-electrode connections, graphic display, and
flexible mode selection buttons.
[0037] FIG. 13 is a schematic diagram showing a block diagram of
circuit elements for cyclical non-simultaneous sequencing to a four
electrodes.
[0038] FIG. 14 is a schematic flow diagram for non-simultaneous
sequencing of generator output to multiple electrodes.
DETAILED DESCRIPTION
[0039] Referring to FIG. 1, an RF generator 1 that can be connected
to multiple electrodes is shown. Signal output from the generator
can connect to output jacks 4, 7, 11, and 14. Electrodes 44, 47,
52, and 54 can be connected to the output jacks by cables 24, 27,
31, and 34, respectively. Mode select switch 3 allows the user to
switch between an individual output mode of the generator 1 wherein
signal output from the generator 1 is connected to individual
electrodes, one at a time, or to a multiple output mode wherein
signal output from the generator 1 is connected in a cyclical,
non-simultaneous sequence to multiple electrodes 44, 47, 51, and
54. The individual mode permits the RF generator signal outputs to
selectively be connected to each electrode individually for the
purpose of doing individual impedance measurements, stimulation
threshold testing, EEG or EMG recording, or individual electrode RF
lesion making. The multiple out mode of the mode select switch
allows therapeutic high frequency signal output from the generator
1 to be delivered to the electrodes 44, 47, 51, and 54 in a
cyclical sequence that is automatically programmed into the
generator 1, so that the high frequency energy is delivered in a
sequential and non-simultaneously time pattern to the multiple
electrodes.
[0040] The individual electrode temperatures can be measured either
in a sequential or in a continuously time pattern and the measured
temperatures can be compared to the user set temperature,
represented by the display 77 and set by the knob 55 in FIG. 1. For
example, in this embodiment the individual electrode temperatures
are displayed on a two-dimensional graphics panel identified by 60
in the figure. Also within the graphics display is a representation
of temperature versus time displayed in graphic format, for
example, as line graphs 61, 62, 63, and 64 in FIG. 1. Indicator
lights, represented, for example, by 65 in FIG. 1, indicates which
electrode or which set of electrodes are being used in the
procedure. In this way the user always knows which electrode is
intended to be active or is activated when the mode select 2 has
been set to a particular electrode or set of electrodes, and will
also indicate during high frequency therapeutic treatment which
electrodes are being involved in the procedure according to the
system and method described herein.
[0041] Referring to FIG. 1, in one example, the high frequency
power source or high frequency generator that delivers the high
frequency signal output and/or low frequency stimulation signal
output pulses could be incorporated into the apparatus 1, or could
be a separate stand-alone unit, with the apparatus 1 being
interposed between the high frequency power source and the
electrodes. In one example, as illustrated in FIG. 1, an AC line 68
can connect the apparatus 1 to an electrical outlet supply power
for the apparatus 1. In another example, apparatus 1 can be a
battery-operated device wherein the power is supplied by a battery
(not shown) that can make the apparatus 1 portable.
[0042] The mode selection 2 can be implemented in many ways, for
example, knobs, pushbuttons, remote control voice control, or other
means. In one example, the features of the user interface of
apparatus 1 could be achieved with or without displays such as 60,
and, in one example, can use up/down pushbuttons rather than
rotatable selector knobs to select or advance or decrease control
levels. In one example, the mode select 2 can connect each
electrode individually to the high frequency power source, and can
also have another position which connects each electrode
independently to an EMG or EEG measuring circuit, where the EMG or
EEG signal can be displayed on a two-dimensional graphics display.
In one example, an additional position on the mode select 2 can
deliver high frequency signal output comprising either, (a) in one
mode, continuous trains of high frequency signal waves, or (b) in
another mode, trains of pulsed high frequency signal bursts. In one
mode, for example, these modes of high frequency signal output can
be delivered by a programmed cyclical sequence non-simultaneously
to multiple electrodes that have been selected by the user to be
active during the procedure. In one example, a feedback circuit can
be incorporated into apparatus 1 which is adapted to maintain each
electrode tip at a temperature equal to a set temperature, for
example, a value set by the by control 55 and displayed, as for
example, by the digital display 77.
[0043] In other possible ergonomic embodiments of this invention,
additional displays, buttons, and/or indicators can be included to
allow and/or assist the operator in controlling the device. For
example, in FIG. 1 an RF `ON` indicator light, represented by 69,
can indicate when high frequency signal output is being delivered
to electrode outputs.
[0044] Referring to FIG. 2, in one example, a logic control diagram
shows a basic feedback mechanism for each of the temperature
controlled electrodes that are connected to the apparatus such as 1
in FIG. 1. High frequency power supply 95 delivers high frequency
signal output. The temperature of the electrode receiving this high
frequency signal output, as measured by a temperature sensor in the
electrode, and the user selected set temperature, are delivered to
a logic circuit decision-making element, and represented by 97. If
the electrode temperature is greater than the user set temperature,
the high frequency power or signal output to that electrode is
reduced or turned off. This action is represented by block 98. Then
this process starts all over again, where the electrode temperature
is once again compared to the user set temperature. Conversely, if
the measured temperature for that particular electrode is less than
the user set temperature the high frequency signal output remains
on or increased, and the electrode temperature is subsequently
compared to the user set temperature. In this way temperature
feedback is realized, which will maintain the electrode temperature
at the same level as the user set temperature.
[0045] Referring to FIG. 3, a schematic diagram is shown, in one
example, of a feedback and control system involving the use of
multiple high frequency electrodes. The system is configured and
controlled so that the electrodes 145, 146 147. The electrodes are
connected to the system, and they are in contact to the patient's
body B. The electrodes receive the signal output from the high
frequency generator supply 100 in a non-simultaneous sequence, so
that an individual electrode receives power from the high frequency
power source during a time slice during which the other electrodes
do not receive the high frequency power. For example, in FIG. 3,
there are three electrodes 145, 146, and 147 that have cable
connections 142, 142, and 143, respectively, to the system. These
connections connect to switches S1, S2, and S3, respectively, that
connect further through connections 101, 102, and 103,
respectively, to the high frequency generator 100 that supplies the
high frequency signal output that energizes the electrodes. In one
example, as illustrated in FIG. 3, the switch S1 is closed in the
time slice corresponding to the state of the system shown in FIG.
3, and at this same time slice the switches S2 and S3 are both
open. Thus in the time slice of FIG. 3, only the electrode 145 can
be activated or connected to the signal output of the high
frequency generator 100. This condition that S1 is closed is
controlled by the controller 131. Controller 131 is connected
logically to controller 132 and to controller 133, that control the
state electrode of switches S2 and S3, respectively, by the
connections 170 and 174. In one example, the controllers 131, 132,
and 133 are logically linked so that only one of the switches S1,
S2, or S3 can be closed at any given time. This means that the
electrodes cannot be energized by the signal output of the high
frequency generate 100 at the same time; that is they are energized
non-simultaneously. For example, at another time, S2 can be closed,
and S1 and S3 must be open. At another time, S3 is closed, and S1
and S2 must be open. In one example, the controllers 131, 132, and
133 can be cyclically synchronized by a common clock signal so that
they close and open the switches automatically in time slices that
repeat according to programmed cycle built into the controllers.
The common clock or the common synchronizer can be a separate
element (not shown) or can be clocks built into one or more of the
controllers 131, 132, or 133. In one example, the controllers 131,
132, and 133 are cyclically activated so that the electrodes are
allotted specific repeatedly cycled time slices in which they are
connected non-simultaneous to the high frequency generator. During
an electrode's allotted time slice, for example, for electrode 1,
the controller for that electrode, for example, controller 131 for
electrode 145, will controller the amplitude or the dwell time of
the signal output from 100 so that the power on electrode 145 will
be such as to drive the temperature, measured by the temperature
sensor 161, toward the set temperature for electrode 145 as set on
121. This is a feedback control on temperature for electrode 1 that
can be carried out by the controller 131.
[0046] Referring to FIG. 3, each of the electrodes has a
temperature sensor built into them indicates by the elements 161,
162, land 163, corresponds to electrodes 145, 146, and 147,
respectively. For example, the temperature sensors can be TC
thermocouple sensors that are commonly used in RF electrodes. The
temperature signal can be fed into the controllers by the
connections 151, 152, land 153, respectively. In one example, there
can be a set temperature control, illustrated by the elements 121,
122, and 123, whereby the user can set a temperature which the
respective electrodes should lock onto during the procedure. As an
illustration of how the circuit can function, electrode 1 can be
chosen, as an example, during the time slot for which it is
energized. The same descriptions can apply to electrode 2 and
electrode 3 during their respective time cycles. Temperature sensor
161 is incorporated into electrode 145 that reports the temperature
at the tip electrode 145. The high frequency power connection 141
connects to the electrode 1 that in turn connects to the tissue
around electrode 145 in the patient's body B. The high frequency
power thus passing into the tissue heats the tissue, and, in turn,
heats up the electrode 1 and the temperature sensor 161 within it.
Temperature measured by 161 is reported via 151 to controller 131.
Control 131 also has an input signal from set temperature control
121, and compares the set temperature to the measured temperature
from 161 to determine how long switch S1 should be closed and when
it should be opened during the allotted time slice for electrode
145. In this way, the electrode temperature can converge to the set
temperature. Switch S1 is shown as a generic switch, and can
comprise electrical, mechanically and/or optically switching
technology. The high frequency power source 100 is connected and
disconnected to electrode 145 via switch S1 and the opening and
closing of S1 is modulated, in one example, via controller 131.
Controller 131 compares the user set temperature from 121 to the
reported electrode tip temperature from sensor 161 and determines
the delivery of the signal output from supply 100 to electrode 145.
This is an example of a feedback circuit is established to maintain
the temperature of electrode 145 at the user set temperature. A
similar feedback control for electrodes 2146 and 147 can be done
during heir respective on-time slots. In this way, the electrodes
can be energized by the high frequency power source in a
non-simultaneous manner, and the temperature on the multiple
electrodes can be controller according to chosen set temperatures
in a relatively continuous manner during the clinical procedure.
The procedure carried out by the illustrative circuit of FIG. 3 can
be done for other numbers of high frequency electrode, for example,
two, or four, or any number of electrodes.
[0047] Referring to FIG. 4, a sequence of time slices T1, T2, T3,
T4, . . . etc are indicated on the vertical axis, and the state of
the switches, as for example, the switches S1, S2, and S3 in FIG.
3, are shown schematically in configuration of open and closed
states. For example, in time slice T1, switch S1 is shown in a
horizontal position 200, meaning that it is closed, and switches S2
and S3 are shown in an open state indicated by the inclined angle
of the schematic switch arms 202 and 204, respectively. This would
be the condition in which the signal output from the high frequency
generator is delivered to electrode associated with S1, as for
example, the electrode 145 in FIG. 3. This state can be controlled
by the controllers, for example, shown in FIG. 3. In the next time
slice T2, S1 is open indicated by 207, S2 is close indicated by
209, and S3 is open indicated by 211. This corresponds to the
signal output being delivered the electrode 146 in FIG. 3, but in
that time slice T2, no signal output is being connected to the
electrodes 145 and 147. In the next time slice, T3, S3 is closed
indicated by 214, and switches S1 and S2 are open indicated by 218
and 219, respectively, so that the electrode 147 in FIG. 3 is
activated, and the other electrodes 145 and 146 are not. This cycle
of switches being opened and closed in successive time slices
continues as shown in FIG. 4. In one example, the length of time of
the time slices can be controlled by the controllers as for
example, 131, 132, and 133 in FIG. 3. The dwell time of signal
output on a particular electrode in a particular time slice can be
modulated by the controllers according to the measured temperature
of the electrodes and the feedback control circuit as describes
with respect to the FIGS. 1, 2, and 3.
[0048] Referring to FIG. 5, in one example, the signal output level
V of the high frequency generator is displayed schematically on the
vertical axis, and the time slices T1, T2, T3, etc are shown
schematically on the horizontal axis. As in the previous figures,
the time slices can correspond to the non-simultaneous time slots
for the opening of the electrodes. In one example, the time slots
can be of equal duration. For example, if the time to cycle through
all of the electrodes is one second, then the individual time
slices for each electrode can have 1/3-second durations. The time
slices T1, T4, T7, etc can corresponds to signal output connection
to electrode 145 of FIG. 1; T2, T5, T8, etc can corresponds to
electrode 146; and T3, T6, T9, etc can corresponds to electrode
147. During each time slice, the controllers, as for example 131,
132, and 133 in FIG. 3, can deliver the appropriate level of signal
output V to the corresponding electrode, whereby, for example, the
temperature of the electrode can be chosen at the set temperature.
In one example, the level of electrode 146 corresponding to T2 is
held at the value V2, then at slice T5 it is held at V5, and at T8
at level V8, and so on, these values being chosen or governed by
the controller of the electrode 146 so that the temperature
measured at the electrode can be held at a desired level. The same
electrode prescription can apply for the other electrodes and their
times slice. One advantage is that because the time slices and the
signal output are non-simultaneously applied, the controllers that
are synchronized to discriminate the time slices can individually
feedback control each electrode separately during their respective
time slices. Another advantage is that since the signal output is
non-simultaneously applied, the high frequency power supply is not
loaded down during each time slice with more than one electrode, so
that it can better maintain it source signal output levels.
[0049] Referring to FIG. 6, another example of a feedback control
method is illustrated schematically. The cyclical time slices for
the electrodes is shown on the horizontal axis, and the signal
output level on the vertical axis as in the FIG. 5. In this
example, during a given time slice sequence such as, for example,
the group of slices T1, T2, and T3, the level is held by the
dependent controllers for the electrodes at VV1. During time slice
T1, the duty time of the output can be controlled by the controller
to be a fraction of the slice time T1, as illustrated by the time
D1. Time duration D1 is controlled so that the temperature of the
electrode 145 is steered back, by a feedback algorithm in the
controller for electrode 145, to the set temperature value.
Similarly, in the next group of time cycles are T4, T5, and T6.
During the time slice T4 in which the electrode 145 is active, the
dwell time of the signal output to the electrode 145 is D4. In T7,
it is D7, and so on. The level at each group of time cycles can be
changed as illustrated in FIG. 6 by the levels VV1, VV2, VV3, and
so on. The level that is maintained and applied at each group of
time cycles, can be determined by the feedback algorithm so that
each and all of the electrodes can get the sufficient power of
signal output during its allotted time slice to achieve the
temperature of the set temperature. This can be done by the
dependent coupling of the controllers, as, for example, indicate by
the coupling lines 170 and 174 shown in FIG. 3.
[0050] Referring to FIG. 7, a schematic block diagram of circuit
elements are shown that can dependently couple the controls for
multiple electrodes E1, E2, E3 that can be connected to a high
frequency generator 250. High frequency generator 250 is connected
by connection 251 to a master controller 254, which controls the
distribution of the signal output of 250 to the secondary
controllers 271, 272, and 273. The secondary controllers, in turn,
send the activation signal to the electrodes E1, E2, and E3,
respectively. In one example, controller 254 comprises a master
clock that determines the group cycle times, the time slices within
the group cycle times, the signal output levels during each time
slice, and/or the dwell times within each time slice corresponding
to the electrode activations by the signal output from 250. This
master control information is sent to the controllers 271, 272, and
273 by the connections 261, 262, and 263. In one example, the
temperature signals from the electrode temperature sensors within
the electrodes E1, E2, E3 are inputted, as illustrated by T11, T22,
and T33, into set temperature controllers 281 282, and 283,
respectively, which then send their signals to the controllers 271,
272, and 273, respectively, for secondary control of signal output
levels and/or dwell times during each electrode time slice. This
can enable the controllers to maintain a desired set temperature
for each electrode. Also, in one example, the connections 261, 262,
and 263 can comprise transport of an information signal back to the
master controller 254 (indicated by the two-way arrow heads on
these connections), based on the measured temperature, the set
temperature, and the time slice parameters, so that master
controller 254 can set the overall signal output level from the
high frequency supply 250. This flow of information and control
from 254 to 250 is schematically illustrated by the two-way arrow
heads on the connection 251.
[0051] Referring to FIG. 7, a connection 300 is shown to a
reference electrode 304. Reference electrode 304 can for example,
be a grounding plate or pad that is connection to the patient's
body skin to act as a return current path for the output of the
high frequency generator. This is a common type of connection. In
another example, the electrode E1, E2, E3, and more if the clinical
need warrants it, can include reference electrode such as electrode
304, so that the system is then connected in multiple bipolar
manner. The reference electrode can be of the same type as high
frequency element normally inserted into the patient's body for RF
lesioning, so that the reference electrode themselves become part
of the therapeutic system, rather than being merely a passive
return path for high frequency current.
[0052] Referring to FIG. 8, a system of multiple electrodes
connected to a high frequency generator is shown wherein the
electrodes are configured in a multiple bipolar manner. In one
example, the multi-bipolar signal outputs from generator 400 are
sent out of jacks 460 and 462, each jack having multiple pin
outputs that can send non-simultaneously cyclical signal outputs to
multiple pin combinations. The cables 411 and 412 carry these
signal outputs through multiple internal cables (not shown in the
figure), and have a multiplicity of continuation cables, such as
441, 443, 445, 447, and 449 from line 411; and 442, 444, 446, 448,
and 445 from line 412. These continuation cables, in turn, connect
to the electrodes EE1, EE3, EE5, EE7, and EE9 for the continuation
lines fanning from 411, respectively; and electrodes EE2, EE4, EE6,
EE8 and EE10 from the continuation lines sited from cable 412,
respectively. In one example, the pairs of bipolar electrodes, for
example, EE1 and EE2 are activated as a bipolar pair, and the high
frequency generator with its internal, non-simultaneous control
functions, as described in connection with the previous figures,
can activate these bipolar pairs to hold a desired set temperatures
on them or to maintain them at a specific signal output level.
Another time slice would apply to the bipolar pair EE2 and EE3 with
their respective time slice and non-simultaneous activation and
controls, and so on for all the bipolar pairs involved.
[0053] Referring to FIG. 8, in another example, the output lines
411 and 412 from the high frequency generate 400 can each carry a
single high frequency bipolar signal that is connected directly
though the connection lines 441 443, 445, 447, and 449 for
connection 411; and 442, 444, 446, 448, and 450 through the
connection 412, respectively. In one example, the opposite polarity
of the high frequency signal output from generator 400 would be
connected to each of the respective pairs in the bipolar
collection. For example, EE1, EE3, EE5, EE7 and EE9 would carry the
plus signal output level, and EE2, EE4, EE6, EE8, EE10 would all
carry the minus signal output value level. Thus the cabling
connection structure comprising 411, 412 in combination with 441
through 450 can be a unitized cable system for delivering bipolar
signal outputs to multiple electrodes in a bipolar RF system. This
can have application when delivering, for example, pulsed RF
signals to multiple bipolar electrode pairs.
[0054] Referring to FIG. 9, in one example, an embodiment of the
user interface is illustrated. Displays 500 are digital indicators
of electrode temperatures and/or other pertinent parameters or
readouts associated with the multiple electrodes that can be
connected to the system. In one example, they can be displayed in
separate displays, and in another example, they can be displayed as
part of a two dimensional screen display, and the design choice can
be dependent on clinical or ergonomic needs. Digital displays of
such parameters or readouts can, for example, be represented by LED
or LCD digits. Element 507 represents a two-dimensional graphics
display, and in FIG. 9 is displaying a graph of temperature from
electrode measurements. The dashed curve 509 can represent the time
course of another parameter, for example, voltage, current, and/or
power delivered on-time the electrode(s). The panel 514 can be the
automatic temperature control panel. The set temperature can be
actuated up and down by the toggle switch, and the set temperature
can be displayed digitally as, for example, 80. The displays or
selector controls, indicated by the element 511, can be lights that
indicate which of the multiple electrodes that the clinician wished
to the active in the procedure, or they can be buttons that enable
the clinician to select which of the multiple electrodes he wishes
to be activated during the procedure. The present system and method
is not restricted to graphics display, but can comprising other
readout or display method and systems, including printout and hard
copy devices. For example, other options for user interface can
comprise the mode selector that can be represented by a series of
buttons that are associated with indicator lights identified as
511. The electrode outputs are schematically shown as elements 517
which, for example, can be electrode jacks. The elements 517 can be
the output jacks that enable connection to cable s that run to the
electrodes.
[0055] Referring to FIG. 10, in one example, the system is shown
wherein the mode selector 600 has a position for EMG or EEG
recording in addition to a stimulation position and a high
frequency signal output delivery position. On the two-dimensional
display 602, an EMG or EEG signal 604 can be represented as a graph
604 of EMG or EEG activity or of EMG/EEG activation signals, thus
identifying electrophysiological activity of a nerve before and/or
after the high frequency treatment. In one example, the elements
612 indicate the electrode output jacks. In the example shown,
there are four electrode output jacks; however any number of
electrodes greater than one is included within the scope of the
present system and method. In one example, the Set Temp user
interface can comprise a knob 614, however there are other
implementations of this control that are possible, such as up/down
switches, slide controls, and so on. Element 620 indicates the set
temperature. Displays 624 can indicate the temperature readout
values from the electrodes' temperature sensors, and in the FIG.
10, for example, they are all showing reading body temperature of
37 degrees which is typically the case before high frequency signal
output is applied to the electrodes.
[0056] Referring to FIG. 11, a schematic representation of the
system is shown. The mode selector 637 is in the stimulation
position. A sensory stimulation graph 630 is displayed. In one
example, the graphs for the stimulation levels can be shown for
four electrodes. Typically, the stimulation signal output level,
for example, voltage, is applied to each electrode independently
and individually, so that the correct position of the electrode tip
can be confirmed on the correct nerve. Each electrode that is
connected to the system and is to be activated has associated with
it a histogram such as 632 indicating, for example, stimulation
sensory thresholds prior to making a heat or a pulsed high
frequency lesion. This can be done for each electrode separately.
There are many possible ways that these stimulation parameters can
be represented. For example, FIG. 11 illustrates one example of the
many such ways in which to achieve a representation of these
stimulation parameters identifiable to the user. The small line 633
can indicate a level that the clinician has selected for that
electrode position and can show for later record what was achieved.
After the heat high frequency lesion, another stimulation testing
can be done for the same electrode, and this can be shown as
another histogram bar graph, for example line 634 together with a
record index level marker 635. Similar bar graphs can be developed
and displayed for the other electrodes, as is illustrated in the
FIG. 11. The mode select switch, identified as 637, has settings
for both delivery of high frequency signal output and for
stimulation signal output. The displays 624 represent the
temperature readouts measured at the electrodes. Typically, when
stimulation is being delivered to the electrodes, there is no high
frequency heating of the electrodes, so that the temperature
readings 624 for the multiple electrodes would indicate body
temperature of 37 degrees. The electrode outputs, represented by
612, can indicate connections to four electrodes, although any
number of electrodes greater than one is anticipated in this
present system and method. Set temperature can be adjusted by knob
640, and an example of a set temperature displayed value is
represented by display 642.
[0057] Referring to FIG. 12, in one example, another user interface
is shown. A mode select button, 700, can allow the user to select
between EMG/EEG, HF, and stimulate modes. In one example, the modes
of: stimulation 750, high frequency output modes 754, recording LOG
758, RAMP of the high frequency output increase 760, EEG or EMG
recording 766, and recording of the parameters used 768, are
actuated by push buttons. When the stimulation or the EMG mode is
selected, digital display(s) or pushbuttons The electrode mode or
configurations used can be represented by other pushbuttons, for
example, 723, which can indicate which electrode is selected.
Integral he electrode modes, the user can select one electrode at
time for EMG/EEG or stimulation activation. The system enables the
user to know which of the multiple possible electrodes that are
being considered is being connected at any given time to the
EMG/EEG or to the stimulation output mode, on-time for the high
frequency treatment. The electrode selection can be made by the
knob or pushbutton as illustrated by element 723. In one example,
the user set temperature is identified as a knob indicated by 720,
and the set temperature value is represented by 722, and this
display, in one example, is incorporated within a two-dimensional
graphics display 726. A time versus temperature graph is indicated
by 730 for the individual electrodes, if high frequency signal
output mode is selected on the mode select, is indicated by 754.
Display 740, in the example, is in FIG. 12, indicative of four
electrode outputs. Dotted circles 741 represent that more than four
electrodes or less than four electrodes can be used, according to
clinical needs.
[0058] Referring to FIG. 13, a schematic diagram of the sequential
flow of high frequency signal output to four electrodes is shown.
The signal output from high frequency generator 800 is distributed
in a timing cycle through the control element 805 which distributes
the signal output as indicated schematically by the rotary arrow
807. 807 is symbolically a `phasor` showing that the output can
first be connected to electrode E1, as shown by the solid arrow
807, and then as time progresses, it is connected to E2, indicated
by the dashed arrow 814. The rotor distributor or `phasor` 807
continues in a schematically indicated dashed clockwise circle 817
representative of the passage of time, so that it connects in turn
with E3 indicated by dashed arrow 820, and E4 indicated by arrow
827, and continues on around the cycle to repeat its connection
automatically to the four electrodes again and again during the
procedure duration. This can be referred to as `cyclodromic`
distribution control of the high frequency signal output to
multiple electrodes. The contact to any electrode is
non-simultaneous to the contact with any other electrode, so the
process can be said to be non-simultaneously cyclodromic.
[0059] Referring to FIG. 14, a flow diagram shows schematically a
process for the method of the present invention, Step 900 comprises
the selection of multiple electrodes to be used according to
clinical needs. Step 900 can include the decision on how many
electrodes are needed to fulfill clinical objectives the procedure.
In one example, the electrodes can be chosen to make heat lesions
at multiple levels of the spine or the medial branches of the
spinal segmental nerves. In step 900, the electrodes can be
connected by cables to the high frequency generator. In step 904,
the electrodes are positioned in the patient's body so that their
tips are at the desired target tissue sites. Step 904 can, for
example, include the steps of stimulation-testing using the motor
and/or physiological stimulation signal output levels and pulse
frequencies that can be user-selected from the system, applied at
each electrode individually. In this way, the appropriate
positioning of the individual electrode tips can be confirmed at
the correct position with respect to the target nerves. In step
907, the desired set temperature can be selected on the interface
of the high frequency generator. In one example, the set
temperature can be the same for all of the electrodes, and, in
another example, the set temperature can be different for the
electrodes, this chose be made by the clinician according to his
clinical needs. In step 911, the clinician can select the number of
multiple electrodes that he desires to activate for the clinical
procedure. The activation of the system can initiate a sequential
and/or cyclical delivery of the high frequency signal output from
the system to the multiple electrodes in such a way that the signal
output is applied in a non-simultaneous time sequence. This can
proceed by automatically delivering the high frequency output to
one electrode at a time corresponding to that electrode's
programmed time slice, and according to a controlled sequence of
time slices for the multiple electrodes, as has been illustrated in
the FIGS. 1 through 13. Step 911 can involve varying the dwell time
and/or the amplitude of the high frequency output to each electrode
during its time slice to maintain set a parameter value, such as
set temperature, as described in FIGS. 1-13.
[0060] The system and method described herein can be used in a
variety of medical applications. In one example, it can be used to
treat neural tissue in the brain, spine, or peripheral anatomy to
manage pain, mood disorders, or movement disorders such as
Parkinson's disease. In another example, it can be used to treat
cancerous tumors anywhere in the patient's body. It can be to treat
many various target tissue sites and disease states, as can be
considered by clinicians and others skilled in the medical art.
[0061] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the followings Claims:
* * * * *