WO2021107649A2

WO2021107649A2 - Apparatus and method for modulating nerve by applying electrical stimulation to nerve of patient

Info

Publication number: WO2021107649A2
Application number: PCT/KR2020/016992
Authority: WO
Inventors: 이기원
Original assignee: (주)와이브레인
Priority date: 2019-11-29
Filing date: 2020-11-26
Publication date: 2021-06-03
Also published as: KR20220017952A; WO2021107649A3

Abstract

The present invention relates to an apparatus for modulating a nerve by applying electrical stimulation to a nerve of a patient, the apparatus comprising: a stimulation module configured to apply a signal to the nerve of the patient; and a controller for controlling the signal applied to the stimulation module, wherein the signal includes bursts of pulses and a direct-current (DC) waveform.

Description

Apparatus and method for controlling nerves by applying electrical stimulation to nerves of a patient

The present invention relates to an apparatus and method for controlling nerves by applying electrical stimulation to the nerves of a patient.

Various attempts are being made to treat a patient's medical disease by applying electrical stimulation to the nerve.

First, there is an implant type that controls the nerve by invasively inserting a device into the body and directly applying electrical stimulation to the nerve. A typical example of the implant type is an attempt to alleviate the main symptoms of asthma or COPD through electrical stimulation, and through this method, the side effects caused by conventional methods such as nerve amputation are reduced while alleviating the main symptoms of asthma or COPD. effect can be obtained.

In addition, there is a non-implant type that non-invasively applies electrical stimulation from the epidermis to reach the nerve. As a representative example of the non-implant type, there is an attempt to alleviate ADHD symptoms through electrical stimulation, and through this method, the effect of reducing the side effects caused by the invasive treatment can be obtained by replacing the conventional invasive treatment. have.

An object of the present invention is to provide a neuromodulation apparatus and method capable of controlling a nerve by applying an electrical stimulus to a patient's nerve by applying a signal including a burst of pulses and a DC waveform.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An apparatus for controlling a nerve by applying electrical stimulation to a nerve of a patient according to the present invention for solving the above-mentioned problems, a stimulation module configured to apply a signal to the nerve of the patient, and a signal applied to the stimulation module a controller, wherein the signal comprises bursts of pulses and a direct current (DC) waveform.

In addition, by providing the electrical stimulation to the nerve of the patient to control the nerve, it is possible to treat a medical condition of the patient.

In addition, the nerve may include at least one of a cranial nerve, a carotid sinus nerve, a vagus nerve, a cervical nerve, and a median nerve.

In addition, the stimulation module includes a contact surface located in a target region of the patient's outer skin, and the signal as an electrical stimulation is applied to the nerve non-invasively through the skin.

Also, the target region may include at least one of a forehead, an ear, a neck, and a wrist.

Also, the signal may be divided into a burst section of a pulse and a DC waveform section, and the controller may control the signal so that the DC waveform section is located between the burst sections of the pulse.

In addition, the burst section of the pulse and the DC waveform section do not overlap, the controller includes the burst of the pulse in the signal in the burst section of the pulse and stops the application of the burst of the pulse in the DC waveform section, The signal may be controlled to include the DC waveform.

Also, in the DC waveform section, the DC waveform may include a waveform that decreases from a relatively large first current value to a relatively small second current value.

In addition, when the DC waveform section is disposed between the burst sections of the pulse in the signal, and the burst section of the pulse is disposed after the DC waveform section in time series, the signal is a signal between the DC waveform section and the pulse. A rest period in which there is no output of the DC waveform may be included between burst periods.

In addition, at least one of a decreasing slope value of the DC waveform in the DC waveform section and a length of the rest section is determined according to the medical disease of the patient to be treated.

In addition, the patient's medical disease is migraine, insomnia, neurologic disorder, neuropathic pain, motor dysfunction, epilepsy, tinnitus, It may include at least one of obesity and depression.

In addition, the frequency of the burst of pulses has a value between about 5 bursts per second and about 10 bursts per second, and the duration of each pulse included in the burst of pulses has a value between about 45 ms and about 100 ms. will be.

In addition, the magnitude of the pulse included in the burst of the pulse has a value of about 10 mA to about 20 mA, and the magnitude of the DC waveform has a value of about 0.5 mA.

In addition, the present invention provides a method for modulating a nerve by applying electrical stimulation to a nerve of a patient, performed by an apparatus, comprising the steps of: positioning a stimulation module in a target area of the patient's epidermis; generating a signal including (bursts of pulses) and a direct current (DC) waveform, and applying the signal to the stimulation module so that electrical stimulation is applied to the patient's nerves non-invasively through the patient's skin includes steps.

In addition to this, another method for implementing the present invention, another system, and a computer-readable recording medium for recording a computer program for executing the method may be further provided.

According to the present invention as described above, it is possible to control the patient's nerves by applying electrical stimulation to the patient's nerves by applying a signal including a pulse burst and a DC waveform non-invasively, thereby causing migraine and insomnia. ), neurologic disorders, and depression can be relieved, and the effect of relaxation can be obtained.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram of a neuromodulation apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing a detailed configuration of a stimulation module included in FIG. 1 .

3 is a view for explaining a stimulation position according to a target nerve.

4 illustrates a signal as an electrical stimulation of a neuromodulation device.

5 is a graph that can confirm the effect of using the neuromodulation device as a major HRV indicator.

6 is a graph that can confirm the effect of using the neuromodulation device as an EDA main indicator.

7 is a flowchart of a method for neuromodulation of a patient according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully understand the scope of the present invention to those skilled in the art, and the present invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. As used herein, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components. Like reference numerals refer to like elements throughout, and "and/or" includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various elements, these elements are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first component mentioned below may be the second component within the spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein will have the meaning commonly understood by those of ordinary skill in the art to which this invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless specifically defined explicitly.

Hereinafter, a neural modulation device 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6 . 1 is a diagram of a neural modulation device 10 according to an embodiment of the present invention, FIG. 2 is a diagram showing a detailed configuration of the stimulation module 20 included in FIG. 1, and FIG. It is a diagram for explaining the location of stimulation, FIG. 4 is an example of a signal as electrical stimulation of the neuromodulation device 10, and FIG. 5 is a view showing the effect of using the neuromodulation device 10 as a major HRV indicator. 6 is a graph in which the effect of using the neuromodulation device 10 can be confirmed as an EDA main indicator.

The nerve modulation device 10 according to the present embodiment is a device for modulating a nerve by applying electrical stimulation to the patient's nerve, and by providing electrical stimulation to the patient's nerve to control the nerve, the patient's medical disease (to treat a medical condition).

Here, to control a nerve may mean to control a nerve activity, and the nerve activity may mean, for example, the amplitude, frequency, and/or pattern of an action potential in a nerve. In some embodiments, modulating nerves may include modulating nerve activity in the sympathetic or parasympathetic system.

The regulation of nerves (or regulation of nerve activity) means that the nerve activity is changed as an electrical stimulus is applied. In some embodiments, the nerve activity may be increased or inhibited (or blocked) after the electrical stimulation is applied compared to before the electrical stimulation is applied according to the regulation of the nerve, and the amplitude and/or frequency of the action potential in the nerve is can be changed. In some embodiments, the pattern of the action potential may be changed before and after the application of the electrical stimulus according to the control of the nerve.

In that a patient's medical disease can be alleviated or prevented according to the control of the nerve, the neuromodulation device 10 can provide an effective treatment for the patient's medical disease.

Referring to FIG. 1 , a neuromodulation device 10 according to an embodiment of the present invention includes a stimulation module 20 and a controller 30 , and in some embodiments, the neuromodulation device 10 is shown in FIG. 1 . It may include relatively more or fewer components than the specified components.

In some embodiments, the components of the neuromodulation device 10 may be physically separated from each other, and do not necessarily have to be located in one housing.

In some embodiments, the neuromodulation device 10 may be a stand type positioned next to a patient, a portable type that a patient or medical staff can carry and move, or a wearable type that a patient can wear, but is not limited thereto.

The stimulation module 20 is configured to apply a signal to the patient's nerves and the operation is controlled by the controller 30 to be described later. The stimulation module 20 may include at least one component necessary for applying a signal to a nerve of a patient, for example, a power source (not shown), an electrode 21 and an outer surface of the patient. It may include, but is not limited to, a contact surface 22 positioned in a target area of . The electrode 21 is a plurality of electrodes 21 and may include an anode and a cathode.

Here, when the contact surface 22 of the stimulation module 20 is located in the target region of the epidermis of the patient, a signal as an electrical stimulation may be applied to the nerve non-invasively through the skin. Specifically, since an electric field formed when a signal as an electrical stimulus is applied passes through the epidermis of the patient and is transmitted to the nerves in the epidermis of the patient, the nerve modulation device 10 according to an embodiment of the present invention When used, electrical stimulation can be applied to nerves non-invasively.

However, in some embodiments, the neuromodulation device 10 of the present invention may not non-invasively apply electrical stimulation to a patient's nerves, but may invasively apply electrical stimulation to a patient's nerves. For example, the neuromodulation device 10 may be mounted in the patient's body in the form of an implant.

Referring to FIG. 2 , the target area of the epidermis of the patient may be the epidermis on the area where the target nerve to which electrical stimulation is to be applied is located, and the target nerve needs to apply electrical stimulation to treat the patient's medical disease. could be nerves. For example, the anode and the cathode may be spaced apart from each other by the plurality of electrodes 21 in the epidermis on the area where the target nerve is located, and the target nerve may be respectively located under the epidermis where the anode and the cathode are located.

The target region may include at least one of a forehead, an ear, a neck, and a wrist, and the target nerve is a cranial nerve and a carotid sinus nerve. , vagus nerve, neck nerve (cervical nerve) and may include at least one of the median nerve (median nerve), the medical disease of the patient to be treated is migraine (migraine), insomnia (insomnia) , neurologic disorder, neuropathic pain, motor dysfunction, epilepsy, tinnitus, obesity, and depression. not limited

Referring to FIG. 3 , when the left carotid sinus nerve (A) and the left vagus nerve (B) are target nerves, the stimulation location as the target area is a patient in which the left carotid sinus nerve (A) and the left vagus nerve (B) are located It may be the epidermis on the side of the neck. Specifically, the cathode may be located in the epidermis on the left carotid sinus nerve (A), the anode may be located in the epidermis on the left vagus nerve (B), and the cathode may be located relatively closer to the head than the anode.

And when the neck nerve is the target nerve, the stimulation location as the target area may be the epidermis on the back of the patient's neck where the neck nerve is located, specifically, the epidermis (C) adjacent to the first cervical vertebrae (C1) and the second cervical vertebrae (C2). ) and the epidermis D adjacent to the third cervical vertebrae C3 and the fourth cervical vertebrae C4. The anode may be located in the epidermis (C) adjacent to the first cervical vertebrae (C1) and the second cervical vertebrae (C2), and the cathode may be located in the epidermis (D) adjacent to the third cervical vertebrae (C3) and the fourth cervical vertebra (C4). , the anode may be located relatively closer to the head than the cathode.

In addition, if the trigeminal nerve belonging to the cranial nerve is the target nerve, the stimulation location as the target area is the supraorbital nerve and the trochlear nerve, which is the first excitation of the optic nerve, which is a branch of the trigeminal nerve It may be the epidermis of the right eyebrow and the epidermis (F) of the left eyebrow, where the supratrochlear nerve is located. Specifically, the cathode may be positioned in the epidermis (E) on the right supraspinatus nerve and the trochlear nerve, and the anode may be positioned in the epidermis (F) on the left supraspinatus orbital and trochlear nerve.

The controller 30 controls the neuromodulation device 10 , and specifically controls a signal applied to the stimulation module 20 . Here, the signal is an electrical signal for electrical stimulation, and includes bursts of pulses and a direct current (DC) waveform.

Referring to FIG. 4 , electrical stimulation refers to an electrical signal, and the electrical signal includes a burst of pulses and a direct current (DC) waveform. The signal is time-series divided into a burst section of a pulse and a DC waveform section, and the controller 30 controls the signal so that a DC waveform section is located between the burst sections of the pulse in time-series, specifically, the burst section of the pulse and the DC Waveform sections may be provided alternately.

In some embodiments, the burst section of the pulse and the DC waveform section do not overlap, the controller 30 determines that the burst section of the pulse includes a burst of pulses and does not include the DC waveform in the signal, and the DC waveform section includes the burst of pulses to stop the application and control so that the DC waveform is included in the signal. Since the burst of the pulse and the DC waveform are generated from the same power source (not shown), the burst section of the pulse and the section of the DC waveform may not overlap.

Looking at the region in which the pulse burst section is converted to the DC waveform section, each pulse has a first current value in the pulse burst section, and the DC waveform has a second current value different from the first current value in the DC waveform section. That is, the first current value may be the target current value of the pulse, and the second current value may be the target current value of the DC waveform. Since the neuromodulation apparatus 10 according to the present embodiment generates signals having different values in time series from the same stimulation module 20, the first current value to the second current value is discontinuous ( discrete) values are difficult to change.

Accordingly, a waveform in which the current value continuously changes from the first current value to the second current value is included in the DC waveform section, and if the first current value is relatively larger than the second current value, the DC waveform in the DC waveform section is and a waveform decreasing from a relatively large first current value to a relatively small second current value.

In the DC waveform section, the DC waveform may substantially maintain the second current value for a predetermined time after reaching the second current value. In the DC waveform section, since the purpose is to apply electrical stimulation to the patient's nerves through the DC waveform having the second current value, the situation in which the DC waveform reaches the second current value is maintained for a predetermined time as described above. can

Here, the decreasing slope value of the DC waveform in the DC waveform section may be determined according to the medical disease of the patient to be treated. For example, the first current value of each pulse included in the pulse burst, the second current value of the DC waveform in the DC waveform section, and other characteristics are determined according to the medical condition of the patient, so that the decrease slope of the DC waveform in the DC waveform section A value can be determined.

Therefore, if the medical condition of the patient is changed, at least one of the burst characteristic of the pulse for treatment and the characteristic of the DC waveform may be changed, and accordingly, the decreasing slope value of the DC waveform may be determined differently in the DC waveform section as well as the DC waveform The length of the rest period between the period and the burst period of the pulse may be determined differently. As the burst characteristics and DC waveform characteristics of pulses, the first current value (mA), frequency (Hz), pulse duration (νs), interpulse duration (νs), ramp-up (s) of the pulses included in the pulse burst , ramp-down (s), total time (s), burst frequency (Hz), burst duration (ms), and a second current value (mA) of the DC waveform may be included.

In some embodiments, referring to FIG. 4 , looking at a region in which the DC waveform section is converted to a burst section of a pulse, the DC waveform has a second current value in the DC waveform section, and each pulse has a second current value in the burst section of the pulse and has a different first current value. Therefore, the region in which the DC waveform section is converted to the burst section of the pulse includes the idle section, and the idle section is a section in which no output is made temporarily, and no DC waveform or pulse burst is output in the idle section. Specifically, when the burst section of the pulse is arranged after the DC waveform section in time series, the signal includes a rest section in which there is no output of the DC waveform or the burst of the pulse between the DC waveform section and the burst section of the pulse.

The second current value of the DC waveform is relatively low compared to the first current value of the pulse. In order to implement the relatively high first current value of the pulse from the relatively low second current value of the DC waveform, a rest period with no output is required. must exist The controller may control to generate a pulse of high energy through this rest period.

Here, the length of the rest period is changed according to the magnitude of the first current value of the pulse, and the controller can control the neuromodulation apparatus 10 so that the length of the rest period becomes longer as the magnitude of the first current value of the pulse increases. have. That is, when the patient's medical condition changes, the magnitude of the first current value of the pulse changes, so that the controller can control the neuromodulation apparatus 10 to change the length of the rest period.

In the neuromodulation apparatus 10 according to an embodiment of the present invention, burst stimulation through bursts of pulses can control the size of nerve signal transmission in nerves, and is a signal for transmitting signals in the brain direction through the ascending nerve pathway. Relief of symptoms can be induced by controlling the way the brain processes body state information. That is, peripheral nerve stimulation through burst stimulation transmits electrical/chemical neurotransmission of peripheral nerves to the central nerve (brain), thereby enabling treatment of central nerve diseases. For example, when a peripheral nerve such as the trigeminal nerve vagus nerve is stimulated through burst stimulation, the stimulus is transmitted to the brain to control the metabolism of the pain control region of the brain. This principle is considered as a treatment principle for migraine.

In addition, in the neuromodulation apparatus 10 according to an embodiment of the present invention, direct current stimulation through a direct current waveform is a signal for increasing or decreasing spontaneous neural activity, and may induce the brain to recognize a specific body state. In the same principle as described above, a signal may be transmitted to the brain, or a signal may be directed in a desired direction by transmitting a signal only to an visceral organ or muscle in which the peripheral nerve terminal extends.

For example, by applying electrical stimulation to the nerve based on the burst of pulses, the patient's medical condition can be alleviated by suppressing the nerve signal transmission related to the patient's medical condition, and applying electrical stimulation to the nerve based on the DC waveform By doing so, it is possible to induce the patient to feel the induced state, such as relaxation.

In some embodiments, the frequency of the bursts of pulses has a value between about 5 bursts per second and about 10 bursts per second, and the duration of each pulse included in the burst of pulses has a value between about 45 vs and about 100 vs. can

In some embodiments, a magnitude of a pulse included in a burst of pulses may have a value between about 10 mA and about 20 mA.

In some embodiments, the magnitude of the DC waveform may be approximately 0.1 mA to 1 mA, and preferably may have a value of approximately 0.5 mA.

The result of applying the electrical stimulation to the patient by setting the neuromodulation device 10 can be confirmed through FIGS. 5 and 6 .

First, referring to FIG. 5 , an immediate stabilization effect through parasympathetic activation based on electrical stimulation even in a stressful situation compared to baseline is confirmed as a major indicator of heart rate variability (HRV).

In addition, referring to FIG. 6 , an immediate stabilization effect through parasympathetic activation based on electrical stimulation is confirmed as a major indicator of EDA (Electrical Dermal Activity) even in a stressful situation compared to the baseline.

Hereinafter, a method of treating a patient's medical disease or a method of controlling a patient's nerves using the neuromodulation apparatus 10 according to embodiments of the present invention will be described with reference to FIG. 7 . However, descriptions of parts overlapping with the description of the neuromodulation apparatus 10 according to embodiments of the present invention will be omitted. 7 is a flowchart of a method for neuromodulation of a patient according to an embodiment of the present invention.

Referring to FIG. 7 , the method for controlling the patient's nerves includes positioning the stimulation module 20 in a target area of the patient's epidermis (S10), and including bursts of pulses and direct current (DC) waveforms. generating a signal (S20) and applying the signal to the stimulation module 20 so that the electrical stimulation is applied to the nerve non-invasively through the skin (30).

Here, in generating the signal ( S20 ), in the DC waveform section, the DC waveform includes a waveform that decreases from a relatively high first current value to a relatively low second current value, and in the DC waveform section, the DC waveform is After reaching the second current value, the second current value is substantially maintained for a predetermined time. The contents related to the generation of the signal described in the neuromodulation apparatus 10 according to the embodiments of the present invention may be directly applied to a method of treating a patient's medical disease.

On the other hand, the frequency of the burst of pulses has a value between approximately 5 bursts per second and approximately 10 bursts per second, and the duration of each pulse included in the burst of pulses has a value between approximately 45 vs and approximately 100 vs, The magnitude of the pulse included in the burst may have a value between about 10 mA and about 20 mA, and the magnitude of the DC waveform may have a value of about 0.5 mA. It has been described in detail in the neural modulation device 10 according to the embodiments.

The steps of a method or algorithm described in relation to an embodiment of the present invention may be implemented directly in hardware, as a software module executed by hardware, or by a combination thereof. A software module may contain random access memory (RAM), read only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, hard disk, removable disk, CD-ROM, or It may reside in any type of computer-readable recording medium well known in the art to which the present invention pertains.

As mentioned above, although embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can realize that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims

As a device for modulating the nerve by applying electrical stimulation to the patient's nerve,

a stimulation module configured to apply a signal to a nerve of the patient; and

Including; a controller for controlling the signal applied to the stimulation module;

wherein the signal comprises bursts of pulses and a direct current (DC) waveform.
According to claim 1,

An apparatus for treating a medical condition of the patient by providing the electrical stimulation to the nerves of the patient to modulate the nerves.
3. The method of claim 2,

The device, wherein the nerve comprises at least one of a cranial nerve, a carotid sinus nerve, a vagus nerve, a cervical nerve, and a median nerve.
3. The method of claim 2,

The stimulation module comprises a contact surface located in a target area of the patient's outer skin,

wherein the signal is applied as an electrical stimulation to a nerve non-invasively through the skin of the patient.
5. The method of claim 4,

wherein the target area comprises at least one of a forehead, an ear, a neck and a wrist.
3. The method of claim 2,

The signal is divided into a burst section of a pulse and a DC waveform section,

The controller is to control the signal so that the DC waveform section is located between the burst sections of the pulse.
7. The method of claim 6,

The burst section of the pulse and the DC waveform section do not overlap,

The controller is configured to control so that the burst of the pulse is included in the signal in the burst period of the pulse, the burst of the pulse is stopped in the DC waveform period, and the DC waveform is included in the signal.
7. The method of claim 6,

In the DC waveform section, the DC waveform includes a waveform that decreases from a relatively large first current value to a relatively small second current value.
9. The method of claim 8,

The DC waveform section is disposed between the burst sections of the pulses in the signal,

When the burst section of the pulse is arranged after the DC waveform section in time series, the signal includes a rest section in which there is no output of the DC waveform between the DC waveform section and the burst section of the pulse .
10. The method of claim 9,

At least one of a decreasing slope value of the DC waveform in the DC waveform section and a length of the rest section is determined according to the medical disease of the patient to be treated.
3. The method of claim 2,

The patient's medical disease is migraine, insomnia, neurologic disorder, neuropathic pain, motor dysfunction, epilepsy, tinnitus, obesity ( A device comprising at least one of obesity and depression.
According to claim 1,

wherein the frequency of the bursts of pulses has a value between approximately 5 bursts per second and approximately 10 bursts per second, and the duration of each pulse included in the burst of pulses has a value between approximately 45 ms and approximately 100 ms. , Device.
13. The method of claim 12,

The magnitude of the pulse included in the burst of the pulse has a value between about 10 mA and about 20 mA,

wherein the magnitude of the DC waveform has a value of approximately 0.5 mA.
In a method of modulating a nerve by applying electrical stimulation to a nerve of a patient, performed by the device,

positioning a stimulation module in a target region of the patient's epidermis;

generating a signal comprising bursts of pulses and a direct current (DC) waveform; and

Applying the signal to the stimulation module so that the electrical stimulation is applied to the nerve of the patient non-invasively through the skin of the patient;
15. The method of claim 14,

The signal generating step is

The pulse is divided into a burst section and a DC waveform section, and the signal is generated so that the DC waveform section is located between the burst sections of the pulse,

The method of claim 1, wherein the burst section of the pulse and the DC waveform section do not overlap.
16. The method of claim 15,

The signal generating step is

In the DC waveform section, the DC waveform includes a waveform that decreases from a relatively large first current value to a relatively small second current value.
17. The method of claim 16,

The signal generating step is

In the DC waveform section, the DC waveform is configured to substantially maintain the second current value for a predetermined time after reaching the second current value.
15. The method of claim 14,

wherein the frequency of the bursts of pulses has a value between approximately 5 bursts per second and approximately 10 bursts per second.
19. The method of claim 18,

and a duration of each pulse included in the burst of pulses has a value between approximately 45 ms and approximately 100 ms.
20. The method of claim 19,

The magnitude of the pulse included in the burst of the pulse has a value between about 10 mA and about 20 mA,

wherein the magnitude of the DC waveform has a value of approximately 0.5 mA.