Method and electrical stimulator for interfering stimulation using axially biased stimulation field

Abstract

An example method for electrically stimulating a subject includes creating a plurality of circuits using an implantable electrode placed within a subject, transmitting a signal at a first frequency through a first circuit of the plurality of circuits, and generating a first electric field, and transmitting a signal of a second frequency through a second circuit of the plurality of circuits, and the second circuit generating a second electric field. The implantable electrode is placed in a substantially linear configuration along a same axis such that the first electric field and the second electric field are in an axially biased configuration, and the first electric field and the second electric field interfere with each other in an overlapping region to produce a beat signal.

Description

[0001] Cross - reference to related applications

[0002] This disclosure claims priority to U.S. Patent Application No. 17 / 900,559, filed on August 31, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to electrical stimulation of a subject, and more particularly, to devices and methods for electrical stimulation using an interference current pattern to treat certain medical conditions. Background Art

[0004] Electrical stimulation of the posterior spinal cord, i.e., spinal cord stimulation (SCS), has evolved into an effective therapeutic tool for treating chronic pain conditions. However, little is known about the activation sites or the neural mechanisms underlying pain relief and functional changes in somatic and visceral structures induced by SCS.

[0005] Spinal cord stimulation is most commonly used in patients with chronic intractable pain syndromes. It is also useful for treating movement disorders and is occasionally used after head injuries. However, one complication of SCS is adaptation or habituation to the stimulation signal. Adaptation refers to when the body becomes accustomed or familiar with an activity or signal and begins to ignore or "filter out the signal". Adaptation can be minimized by varying the signal or keeping the signal focus moving.

[0006] Dorsal column stimulation (DCS) or SCS using current patterns has been shown to be helpful in treating chronic pain disorders in patients. Traditional SCS stimulation may be limited because as the stimulation intensity increases, the stimulation electric field spreads in the cerebrospinal fluid. This is because cerebrospinal fluid (CSF) has a high electrical conductivity property compared to the low - conductivity property of the spinal cord tissue itself. Patient satisfaction with electrical stimulation is often impaired by the recruitment of adjacent neural structures that may cause discomfort, muscle contractions, or even direct pain when activated. Therefore, the efficacy of this therapy is limited.

[0007] Electrical stimulation has also been shown to be beneficial in treating certain other medical conditions. The success of the treatment is generally limited by the ability of the stimulation to be effectively transmitted and maintained at the pain site of the subject. Summary of the Invention

[0008] In an example, a method of electrically stimulating a subject is described, including creating a plurality of circuits using implantable electrodes placed within the subject, transmitting a signal of a first frequency through a first circuit of the plurality of circuits, and the first circuit generating a first electric field, and transmitting a signal of a second frequency through a second circuit of the plurality of circuits, and the second circuit generating a second electric field. The implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and the first electric field and the second electric field interfere with each other in an overlapping region to generate a beat signal.

[0009] In other examples, a method of electrically stimulating a subject is described, including transmitting a signal of a first frequency through a first circuit created between a first pair of implantable electrodes placed within the subject, and the first circuit generating a first electric field, and transmitting a signal of a second frequency through a second circuit created between a second pair of implantable electrodes placed within the subject, and the second circuit generating a second electric field. The first pair of implantable electrodes and the second pair of implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and the first electric field and the second electric field interfere with each other in an overlapping region to generate a beat signal.

[0010] In other examples, an electrical stimulator for electrically stimulating a subject is described, including an interference current generator and a plurality of circuits created using implantable electrodes. The interference current generator generates an interference alternating current output including a first signal and a second signal. The implantable electrodes have a first end and a second end, the first end being coupled to the interference current generator, and the second end being configured to be placed within the subject. The first signal is transmitted through a first circuit of the plurality of circuits to generate a first electric field, the second signal is transmitted through a second circuit of the plurality of circuits to generate a second electric field, and the implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field of the first circuit and the second electric field of the second circuit are in an axially offset configuration. The first electric field and the second electric field interfere with each other in an overlapping region to generate a beat signal.

[0011] These and other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art upon reading the following detailed description, where appropriate reference is made to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Many aspects of the present disclosure can be understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale. Further, in the drawings, like reference numerals designate corresponding parts in multiple views.

[0013] Figure 1 Shows an example of an electrical stimulator for electrically stimulating a subject according to an example embodiment.

[0014] Figure 2 Shows an example of a quadripolar lead on which implantable electrodes are provided according to an example embodiment.

[0015] Figure 3 Shows a single lead with multiple electrodes according to an example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0016] Figure 4 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0017] Figure 5 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0018] Figure 6 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0019] Figure 7 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0020] Figure 8 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0021] Figure 9 Shows a single lead with multiple electrodes according to another example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0022] Figure 10 Shows a dual lead arrangement with multiple electrodes according to an example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0023] Figure 11 Shows a dual lead arrangement with multiple electrodes according to an example embodiment, in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation.

[0024] Figure 12Including an example embodiment, a diagram showing a sine wave representation of a first signal, a second signal, and a resulting beat signal is presented.

[0025] Figure 13 A flowchart showing an example method for electrically stimulating a subject according to an example embodiment is shown.

[0026] Figure 14 A flowchart showing an example method for electrically stimulating a subject according to an example embodiment is shown. Detailed Description

[0027] Example methods and systems are described herein. It should be understood that the terms "example", "exemplary", and "illustrative" are used herein to mean "as an example, instance, or illustration". Any embodiment described herein as "example", "exemplary", or "illustrative" is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example embodiments described herein are not intended to be limiting. It is to be fully understood that the aspects of the present disclosure, as generally described herein and shown in the figures, can be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are explicitly contemplated herein.

[0028] The examples described herein provide devices and methods for electrically stimulating a subject, for example, for a variety of different types of treatments and applications. In an example, an electrical stimulator including an implantable electrode is provided, and interference stimulation is used to generate a beat frequency signal that is directionally controlled to an appropriate target within the subject. The effective area of the stimulation is controlled by the number of electrodes, the placement of the electrodes, and the direction of the electrode interference pattern.

[0029] Compared to other standard implantable stimulation systems and their associated surgical leads, interference current provides directional control, less adaptation or habituation, and greater penetration depth. The amplitude output in each circuit can be modulated to increase the target stimulation area. In an example, in order to use the modulation of the circuit output to target a specific area of the subject, the beat frequency signal is directionally controlled and / or the penetration depth is controlled.

[0030] Figure 1Shows an example of an electrical stimulator 100 for electrically stimulating a subject according to an example embodiment. The electrical stimulator 100 includes an interference current generator 102 that generates an interference alternating current output including a first signal 104 and a second signal 106, and a plurality of circuits created using an implantable electrode 108. The implantable electrode 108 has a first end and a second end. The first end is coupled to the interference current generator 102, and the second end is configured to be placed within the subject, such as in the tissue 110 of the subject. The first end is connected to the second end by a wire or a wire pad. The second end includes a portion of the electrode capable of delivering an electrical pulse and can thus be an electrode pad. In one example, the implantable electrode 108 (or the portion of the implantable electrode including the electrode pad) is implanted into the dura mater within the epidural space 112 at a predetermined position near the spinal cord 114 of the subject. Other example uses will be described below.

[0031] The electrical stimulator 100 described herein can be fully implanted within the subject, or portions of the electrical stimulator 100 can be implanted and portions remain outside the subject. As an example, as described, the implantable electrode 108 can be implantable, and the interference current generator 102 and the power source can be located outside the body and coupled to the implanted electrode 108 by wires. In other examples, the coupling can occur via a wireless link (e.g., a radio frequency (RF) link) from the interference current generator 102 to the implantable electrode 108 such that the electrode is implanted and the interference current generator 102 is not implanted. The RF carrier frequency can be in the MHz, GHz, or THz range and will induce a current in an implant receiver linked or connected to the implantable electrode 108. The RF carrier frequency can range from about 1 MHz to about 20 THz.

[0032] In other examples, the interference current generator 102 can be implanted within the subject (and the power source connected to the interference current generator 102 can also be implanted), and the implantable electrode 108 is further implanted. As an example, the interference current generator 102 can be implanted in a location near or within the brachial plexus or near or below the twelfth rib.

[0033] In the operation of the electrical stimulator 100, the first signal 104 is transmitted through a first circuit of the plurality of circuits to generate a first electric field; the second signal 106 is transmitted through a second circuit of the plurality of circuits to generate a second electric field; and the implantable electrode 108 is placed in a substantially linear configuration along the same axis such that the first electric field of the first circuit and the second electric field of the second circuit are in an axially offset configuration. The two electric fields interfere with each other in an overlapping region, thereby generating a beat signal. The first electric field interferes with the second electric field in the overlapping region to generate a beat signal.

[0034] In some examples, the electrical stimulator 100 further includes a processor 116, coupled to the interferential current generator 102, and the processor 116 is programmed to cause the interferential current generator 102 to send a first signal 104 and a second signal 106 at a selected frequency, voltage level, and time period.

[0035] The interferential current generator 102 includes a pulse generator 118 that generates digital signal pulses, and the processor 116 is connected to or communicates with the pulse generator 118 to cause the generation of the digital signal pulses to approximate a sine-wave-like output waveform. For example, the output can be a sine wave, a pseudo sinewave, or some in-phase sine-wave-like continuous waveform. In other examples, the output includes a square wave.

[0036] The pulse generator 118 generates individual pulses of different widths and resultant amplitudes. In some examples, the pulse width is set in the range from about 0 to about 2.5 microseconds (ms), from about 2.5 ms to about 5 ms, or from about 5 ms to about 10 ms. When these different pulses are driven into a transformer (not shown), a pseudo sine wave is produced.

[0037] The pulse generator 118 also generates a range of outputs, such as amplitudes in the range from about 5 mA to about 9 mA, about 9 mA to about 10 mA, and about 10 mA to about 18 mA, depending on the patient's needs in pain treatment.

[0038] The processor 116 can be or include a field-programmable gate array (FPGA) for shaping multiple pulsating waveforms to approximate the output of a sine wave generator, instead of or in addition to a digital signal processor. An FPGA is an integrated circuit that can be programmed in the field after manufacturing and allows its user to adjust the circuit output as needed. Thus, in alternative examples, the processor 116 can be replaced by an FPGA. FPGA devices can allow complex digital signal processing applications, such as finite impulse response filters, forward error correction, modulation and demodulation, encryption, and applications.

[0039] The processor 116 can include internal memory (non-transitory memory as well as buffer / temporary type memory) for storing execution instructions that cause the electrical stimulator 100 to perform the functions described herein. Additionally or alternatively, in one example, the electrical stimulator 100 includes discrete internal memory that communicates with the processor (via a conventional bus), and the internal memory stores execution instructions that cause the electrical stimulator 100 to perform the functions described herein.

[0040] The electrical stimulator 100 can also include additional components, such as a power supply and other circuitry that perform the functions described herein.

[0041] In the example, as described above, the processor 116 communicates with the interference current generator 102 such that the interference current generator 102 sends different signals for generating the waveforms of the electrical stimulation therapy during different time periods.

[0042] Figure 2 An example of a quadripolar lead 120a - b on which an implantable electrode 108 is provided is shown according to an example embodiment. Figure 2 Two quadripolar leads 120a - b are shown; however, more or fewer leads may be used depending on the placement and arrangement of the electrodes. Each quadripolar lead 120a - b includes a plurality of implantable electrodes, shown as four electrode pads 122a - d and 124a - d. The use of quadripolar leads allows for a larger target therapeutic stimulation area. However, the electrical stimulator of the present disclosure may also be applied to the use of bipolar or octupolar lead systems, and other suitable devices having any number of electrode pads (including, for example, four, six, eight, ten, …, or, for example, up to thirty or thirty - two). The quadripolar leads 120a - b include first ends 126a - b coupled to the current generator 102. The implantable electrodes 108 may be activated in various combinations and patterns, not only as shown in the illustration.

[0043] In operation, the current generator 102 generates an interference output including a first signal 104 and a second signal 106 having different first and second frequencies. A selected electrode among the implantable electrodes 108 carries one of the first signal 104 and the second signal 106 to create separate circuits. When interference occurs between a first circuit (created between two electrodes) and a second circuit (created between two electrodes), the resulting beat frequency will be the difference between the frequencies of the two circuits, and the amplitude will be superimposed and greater than either circuit alone. In other examples, the resulting beat frequency signal may have a frequency in the range of greater than 250 Hz to about 15,000 Hz.

[0044] In many of the examples described below, multiple circuits are created among the implantable electrodes 108 in a variety of ways. For example, multiple circuits can be created using three electrodes, where one electrode is common to two circuits. In other examples, multiple circuits can be created using four electrodes, thereby creating separate circuits between separate pairs of electrodes. Additionally, multiple circuits can be created using the electrodes on a single lead, or using two separate leads placed in a substantially end - to - end basic linear configuration with a distance measured perpendicular to the same axis between the first lead and the second lead of less than about 2 mm.

[0045] Thus, in some examples, the implantable electrodes 108 are included on a single lead, and the implantable electrodes 108 are independently controllable to be arranged as positive and negative electrode pairs for creating a first circuit and a second circuit using a single lead. Additionally, using a single lead, multiple circuits can be created such that a first circuit is between a first implantable electrode and a second implantable electrode, and a second circuit is between the first implantable electrode and a third implantable electrode, and the first circuit and the second circuit have a common implantable electrode. In other examples, using a single lead, multiple circuits can be created such that a first circuit is between a first implantable electrode and a second implantable electrode, and a second circuit is between a third implantable electrode and a fourth implantable electrode.

[0046] In still other examples, the implantable electrodes include a first pair of implantable electrodes and a second pair of implantable electrodes placed in a substantially linear configuration along the same axis.

[0047] In summary, multiple circuits can be created in a variety of ways, including using three electrodes on a single lead, using four electrodes on a single lead, using more than four electrodes on a single lead (e.g., for more than two circuits), using three electrodes from two different leads, using four electrodes from two different leads, or using more than four electrodes from two different leads. Examples will be described and shown in the illustrations below.

[0048] Figure 3 Shown is a single lead 130 with multiple electrodes according to an example embodiment in which multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation. The lead 130 includes implantable electrodes 132a - d, and in one example, the lead 130 can take the form of one of the leads 120a - b shown in Figure 2 (although the lead 130 is also shown to include additional unlabeled electrodes).

[0049] Each implantable electrode 132a - d is independently controllable to operate as a cathode or an anode, and any combination of the implantable electrodes 132a - d can be selected to create one or more circuits. For physiological purposes, nerves have a negative internal charge and are polarized at rest to prepare for excitation, and electrons (negative internal charge) attract positive charges outside the nerve, causing depolarization. Thus, physiologically, the cathode is considered the negative contact, while the anode is the location where negative charge accumulates, and thus the anode is considered the positive contact that attracts negative charges.

[0050] In Figure 3In [the example], a first circuit is created between implantable electrodes 132a and 132b by arranging implantable electrode 132a as the cathode or negative contact and implantable electrode 132b as the anode or positive contact. A second circuit is created between implantable electrodes 132a and 132c by arranging implantable electrode 132c as another anode or positive contact. In this example, the first circuit and the second circuit share implantable electrode 132a as the anode, and implantable electrode 132d is not used.

[0051] In Figure 3 In the operation of the arrangement shown, three electrodes of lead 130 are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit to generate a first electric field 134, transmit a signal of a second frequency through the second circuit to generate a second electric field 136, and the first electric field 134 and the second electric field 134 interfere with each other in the overlapping region 138 to generate a beat signal. When the first electric field 134 and the second electric field 136 are superimposed or overlapped, the generated beat signal will be the difference between the frequencies of the two circuits, and the amplitude will be superimposed and greater than that of either circuit alone.

[0052] In Figure 3 [the example], implantable electrodes 132a, 132b, and 132c are placed along the same axis in a substantially linear configuration such that the first electric field 134 and the second electric field 136 are in an axially offset configuration.

[0053] Figure 4 [Another example embodiment] is shown, in which a single lead 130 with multiple electrodes is provided to create multiple circuits for generating axially offset configuration electric fields for electrical stimulation. In Figure 4 [the example], a first circuit is created between implantable electrodes 132a and 132b by arranging implantable electrode 132a as the anode or positive contact and implantable electrode 132b as the cathode or negative contact. A second circuit is created between implantable electrodes 132b and 132c by arranging implantable electrode 132c as another anode or positive contact. In this example, the first circuit and the second circuit share implantable electrode 132b as the cathode.

[0054] In Figure 4In operation of the arrangement shown, three electrodes of lead 130 are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 136 interfere with each other in an overlapping region 138 to generate a beat signal. When the first electric field 134 and the second electric field 136 are superposed or overlapped, the generated beat signal will be the difference between the two circuit frequencies, and the amplitude will be superposed and greater than that of either circuit alone.

[0055] Similar to Figure 3 the arrangement in, in Figure 4 , implantable electrodes 132a, 132b, and 132c are placed in a substantially linear configuration along the same axis such that the first electric field 134 and the second electric field 136 are in an axially offset configuration.

[0056] Thus, as shown in the examples of Figure 3 and Figure 4 , a single lead 130 includes a plurality of electrodes arranged as a linear electrode array along an axis, and by changing the selection of electrodes used along the single lead, the longitudinal positioning of the beat signal (or overlapping region 138) can be changed. Similarly, by changing the configuration of the first circuit and the second circuit to be operated or to be differently operated among the plurality of electrodes in the linear electrode array, the longitudinal positioning of the beat signal can be changed. For example, changing the shared or common electrode 132b from the Figure 3 anode in to the Figure 4 cathode in changes the way the electric fields interfere to generate the beat signal.

[0057] Interference current generator 120 can be operated in a variety of ways to transmit a first signal 104 and a second signal 106 of different frequencies. In one example, transmitting a signal of a first frequency through the first circuit includes transmitting a signal at a frequency between about 1,000 Hz and about 20,000 Hz, while transmitting a signal of a second frequency through the second circuit includes transmitting a signal at a frequency between about 1,000 Hz and about 20,000 Hz. To generate a beat signal, the first frequency is different from the second frequency.

[0058] The frequency of the signal can be transmitted through the first circuit and the second circuit, within a range of approximately 0 to approximately 20,000 Hz, or any range that can cause the beat signal to have a frequency within a range such as greater than 0 Hz to approximately 5,000 Hz. The beat signal frequency is caused by the interference of two signals from the first circuit and the second circuit (for example, when the first circuit creating the first electric field interferes with the second electric field generated by the second circuit at a frequency of 12,000 Hz, resulting in a beat signal frequency of approximately 2,000 Hz).

[0059] Based on the combination of frequencies used and transmitted in the first circuit and the second circuit, the beat signal can be within a range greater than 0 Hz to approximately 5,000 Hz. Thus, in the example, the signal is transmitted in a frequency range between approximately 12,000 Hz and approximately 15,000 Hz, between approximately 13,000 Hz and approximately 15,000 Hz, between approximately 14,000 Hz and approximately 15,000 Hz, between approximately 10,000 Hz and approximately 15,000 Hz, between approximately 6,000 Hz and approximately 9,000 Hz, between approximately 7,000 Hz and approximately 9,000 Hz, between approximately 8,000 Hz and approximately 9,000 Hz, between approximately 9,000 Hz and approximately 12,000 Hz, between approximately 10,000 Hz and approximately 12,000 Hz, between approximately 11,000 Hz and approximately 13,000 Hz, between approximately 13,000 Hz and approximately 15,000 Hz, between approximately 3,000 Hz and approximately 5,000 Hz, between approximately 3,000 Hz and approximately 7,000 Hz, between approximately 3,000 Hz and approximately 6,000 Hz, between approximately 5,000 Hz and approximately 8,000 Hz, between approximately 1,000 Hz and approximately 5,000 Hz, or any other frequency range between 1,000 Hz and 20,000 Hz.

[0060] Therefore, any signal with a frequency range between approximately 1,000 Hz and 20,000 Hz can be used and transmitted to the first circuit and the second circuit to generate electric field interference, thereby resulting in a beat signal with a frequency range of approximately 0 to 5,000 beats per second (BPS).

[0061] Figure 5 Shows another exemplary embodiment, in which a plurality of circuits are created to generate a single lead 130 with multiple electrodes for an axially biased configuration electric field for electrical stimulation. In Figure 5In [the example], a first circuit is created between implantable electrodes 132a and 132c by arranging implantable electrode 132a as the cathode or negative contact and implantable electrode 132c as the anode or positive contact. A second circuit is created between implantable electrodes 132b and 132d by arranging implantable electrode 132b as the anode or positive contact and implantable electrode 132d as the cathode or negative contact. In this example, the first circuit and the second circuit do not share any implantable electrodes, and each of the first circuit and the second circuit uses a different pair of implantable electrodes to create [the circuit].

[0062] In Figure 5 the operation of the arrangement shown, four electrodes of lead 130 are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 134 interfere with each other in the overlapping region 138 to produce a beat signal. When the first electric field 134 and the second electric field 136 are superimposed or overlapped, the resulting beat signal will be the difference between the frequencies of the two circuits, and the amplitude will be superimposed and greater than that of either circuit alone.

[0063] In Figure 5 [the example], implantable electrodes 132a, 132b, 132c, and 132d are placed in a substantially linear configuration along the same axis such that the first electric field 134 and the second electric field 136 are in an axially offset configuration.

[0064] Figure 6 [Another example embodiment] is shown, where a single lead 130 with multiple electrodes is created with multiple circuits to generate an axially offset configuration electric field for electrical stimulation. In Figure 6 [the example], a first circuit is created between implantable electrodes 132a' and 132c by arranging implantable electrode 132a' as the anode or positive contact and implantable electrode 132c as the cathode or negative contact. A second circuit is created between implantable electrodes 132b' and 132d' by arranging implantable electrode 132b' as the cathode or negative contact and implantable electrode 132d' as the anode or positive contact. In this example, the first circuit and the second circuit do not share any implantable electrodes, and each of the first circuit and the second circuit uses a different pair of implantable electrodes to create [the circuit]. Additionally, in Figure 6 [the example], implantable electrodes 132a, 132b, and 132d are not operated.

[0065] In Figure 6In operation of the illustrated arrangement, four electrodes of lead 130 are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 134 interfere with each other in the overlapping region 138 to generate a beat signal. When the first electric field 134 and the second electric field 136 are superimposed or overlapped, the generated beat signal will be the difference between the two circuit frequencies, and the amplitude will be superimposed and greater than either circuit alone.

[0066] In Figure 6 it, implantable electrodes 132a’, 132b’, 132c and 132d’ are placed along the same axis in a substantially linear configuration such that the first electric field 134 and the second electric field 136 are in an axially offset configuration.

[0067] In Figure 5 and Figure 6 In the arrangement shown, a first circuit is created between a first pair of implantable electrodes within a subject, and a second circuit is created between a second pair of implantable electrodes within the subject. Each of the first pair of implantable electrodes and the second pair of implantable electrodes is placed along the same axis in a substantially linear configuration such that the first electric field and the second electric field are in an axially offset configuration. Additionally, the first pair of implantable electrodes and the second pair of implantable electrodes are included on a single lead 130. As shown, changing the selection of the first electrode in the first pair of implantable electrodes on the single lead 130 changes the longitudinal location of the beat signal.

[0068] Figures 7 - 9 Further examples are shown using a single lead 130 with four electrodes, operated in different configurations to create multiple circuits and the resulting beat signals at different locations.

[0069] Figure 7 Another example embodiment is shown where a single lead 130 with multiple electrodes is created with multiple circuits to generate axially offset configuration electric fields for electrical stimulation. In Figure 7 it, the single lead 130 is shown including eight electrodes, labeled 132a - h. A first circuit is created between implantable electrodes 132a and 132d by arranging implantable electrode 132a as the anode or positive contact and arranging implantable electrode 132d as the cathode or negative contact. A second circuit is created between implantable electrodes 132c and 132f by arranging implantable electrode 132c as the cathode or negative contact and arranging implantable electrode 132f as the anode or positive contact. In this example, the first circuit and the second circuit do not share any implantable electrodes, and each of the first circuit and the second circuit is created using different pairs of implantable electrodes. Additionally, inFigure 7 Among them, the implantable electrodes 132b, 132e, 132g, and 132h are not operated.

[0070] In Figure 7 In the operation of the arrangement shown, four electrodes of the lead 130 are used to create two separate circuits. Subsequently, the interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 134 interfere with each other in the overlapping region 138 to generate a beat signal.

[0071] Figure 8 Shows another exemplary embodiment, in which multiple circuits are created to generate a single lead 130 with multiple electrodes for an axially biased configuration electric field for electrical stimulation. In Figure 8 Among them, the first circuit is created between the implantable electrodes 132b and 132f by arranging the implantable electrode 132b as the cathode or negative contact and arranging the implantable electrode 132f as the anode or positive contact. The second circuit is created between the implantable electrodes 132a and 132c by arranging the implantable electrode 132a as the anode or positive contact and arranging the implantable electrode 132c as the cathode or negative contact. In this example, the first circuit and the second circuit do not share any implantable electrodes, and each of the first circuit and the second circuit uses a different pair of implantable electrodes to create. In addition, in Figure 8 Among them, the implantable electrodes 132d, 132e, 132g, and 132h are not operated.

[0072] In Figure 8 In the operation of the arrangement shown, four electrodes of the lead 130 are used to create two separate circuits. Subsequently, the interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 136 interfere with each other in the overlapping region 138 to generate a beat signal.

[0073] Figure 9 Shows another exemplary embodiment, in which multiple circuits are created to generate a single lead 130 with multiple electrodes for an axially biased configuration electric field for electrical stimulation. In Figure 9In [the example], a first circuit is created between implantable electrodes 132c and 132h by arranging implantable electrode 132c as the cathode or negative contact and implantable electrode 132h as the anode or positive contact. A second circuit is created between implantable electrodes 132a and 132f by arranging implantable electrode 132a as the anode or positive contact and implantable electrode 132f as the cathode or negative contact. In this example, the first circuit and the second circuit do not share any implantable electrodes, and each of the first circuit and the second circuit uses a different pair of implantable electrodes to create. Additionally, in Figure 9 implantable electrodes 132b, 132d, 132e, and 132g are not operated.

[0074] In Figure 9 the operation of the arrangement shown, four electrodes of lead 130 are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 134, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 136, and the first electric field 134 and the second electric field 136 interfere with each other in the overlapping region 138 to generate a beat signal.

[0075] In Figures 7 - 9 each of [the examples], the implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field 134 and the second electric field 136 are in an axially offset configuration. As Figures 7 - 9 shown, by varying the electrode selection used to create multiple circuits, the position of the beat signal can be longitudinally moved along the axis. Additionally, the shape or focus of the beat signal can also be changed to make it narrower (as Figure 7 shown) or longer (as Figure 9 shown).

[0076] Figure 10 shows a dual-lead arrangement with multiple electrodes according to an example embodiment, where multiple circuits are created to generate axially offset configuration electric fields for electrical stimulation. In Figure 10 the example, first lead 140 and second lead 142 each include implantable electrodes. Two circuits are created using three electrodes, where each circuit shares a common cathode or negative contact. For example, the first circuit is created between implantable electrode 144 (arranged as the anode or positive contact) on lead 142 and implantable electrode 146 (arranged as the cathode or negative contact) on lead 142. The second circuit is created between implantable electrode 148 (arranged as the anode or positive contact) on lead 140 and implantable electrode 146 (arranged as the cathode or negative contact) on lead 142.

[0077] In Figure 10In operation of the arrangement shown, three electrodes (one on lead 140 and two on lead 142) are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit to generate a first electric field 150, transmit a signal of a second frequency through the second circuit to generate a second electric field 152, and the first electric field 150 and the second electric field 152 interfere with each other in an overlapping region 154 to produce a beat signal.

[0078] In Figure 10 , the first lead 140 and the second lead 142 are placed along the same axis in a substantially linear configuration, and the distance measured perpendicular to the same axis between the first lead 140 and the second lead 142 is less than about 2 mm. In Figure 10 , the first lead 140 and the second lead 142 are shown as being directly adjacent to each other such that the distance measured perpendicular to the same axis between the first lead 140 and the second lead 142 is effectively zero mm.

[0079] In other examples, a dual-lead arrangement is implemented such that the first lead 140 and the second lead 142 are placed in a substantially linear configuration that is generally end-to-end, and the distance (d) measured perpendicular to the same axis between the first lead 140 and the second lead 142 is less than about 2 mm. In other examples, the distance (d) is less than about 1 mm, less than about 1 mm - 2 mm, or less than about 0.5 - 1 mm.

[0080] Figure 11 Shows a dual-lead arrangement with multiple electrodes according to an example embodiment, where multiple circuits are created to generate an axially biased configuration electric field for electrical stimulation. In Figure 11 , the first lead 140 and the second lead 142 each include implantable electrodes. Two circuits are created using four electrodes, where each circuit uses a separate pair of electrodes, with one electrode on the first lead 140 and one electrode on the second lead 142. For example, the first circuit is created between the implantable electrode 156 (arranged as an anode or positive contact) on lead 140 and the implantable electrode 158 (arranged as a cathode or negative contact) on lead 142. The second circuit is created between the implantable electrode 160 (arranged as an anode or positive contact) on lead 140 and the implantable electrode 162 (arranged as a cathode or negative contact) on lead 142.

[0081] In Figure 11In operation of the arrangement shown, four electrodes (two on lead 140 and two on lead 142) are used to create two separate circuits. Subsequently, interference current generator 102 is operated to transmit a signal of a first frequency through the first circuit, thereby generating a first electric field 164, transmit a signal of a second frequency through the second circuit, thereby generating a second electric field 166, and the first electric field 150 and the second electric field 152 interfere with each other in the overlapping region 168 to produce a beat signal.

[0082] In Figure 11 it, the first lead 140 and the second lead 142 are placed along the same axis in a substantially linear configuration, and the distance measured perpendicular to the same axis between the first lead 140 and the second lead 142 is less than about 2 mm. In Figure 11 it, the first lead 140 and the second lead 142 are shown to be directly adjacent to each other, and thus, the first lead 140 and the second lead 142 are placed in a substantially linear configuration that is generally end-to-end, such that at least one electrode on the first lead 140 is placed adjacent to at least one electrode on the second lead 142.

[0083] In some examples, the first circuit is created using implantable electrodes on the first lead 140, and the second circuit is created using implantable electrodes on the second lead 142. By placing the first lead 140 and the second lead 142 along the same axis, as Figure 11 shown, an axial bias configuration can be established.

[0084] Thus, in the examples described herein, an axial bias configuration can be implemented to generate a beat signal useful for electrical stimulation. The axial bias configuration can be established, for example, using three electrodes on a single lead, using four electrodes on a single lead, using three electrodes from two different leads, or using four electrodes from two different leads.

[0085] Figure 12 Including according to an example embodiment, a graph showing a sine wave representation of a first signal, a second signal, and the resulting beat signal is presented. In Figure 12 it, a first signal having a first frequency of 4,000 Hz passes through the first circuit (which can be any of the first circuits shown and described with reference to Figures 3 - 11 ), and a second signal having a second frequency of 4,100 Hz passes through the second circuit (which can be any of the second circuits shown and described with reference to Figures 3 - 11 ). The interference of the electric fields generated by the transmission of the first signal and the second signal results in the generation of a beat signal. When two waves of different frequencies interfere, the waves are either constructive (additive amplitude) or destructive (subtractive amplitude). When the amplitudes are equal, a well-defined beat will occur. The frequency of the beat signal is the difference between the two carrier frequencies. ForFigure 12 In the example shown, the beat frequency is 100 Hz.

[0086] Figure 13 FIG. shows a flowchart of an example method 200 for electrically stimulating a subject according to an example embodiment. Figure 13 The method shown presents, for example, a method that can be used by the stimulator 100 shown in Figure 1 and an example of a method that can be performed by components of the stimulator 100 in Figure 1 In some cases, the components of the stimulator 100 can be configured to perform functions such that the components are actually configured and structured (using hardware and / or software) to enable such performance. In other examples, such as when operating in a particular manner, the components of a device and / or system can be arranged to be adapted to, capable of, or suitable for performing functions. The method can include one or more operations, functions, or actions shown in one or more of blocks 202-206. Although these blocks are shown in sequence, these blocks can also be performed in parallel and / or in an order different from that described herein. Additionally, depending on the desired implementation, the individual blocks can be combined into fewer blocks, broken into additional blocks, and / or removed.

[0087] In still further examples, the functions of the methods described herein are performed by a circuit (processor) that executes instructions stored on a non-transitory computer-readable medium to cause an electrical stimulator to provide a stimulation treatment.

[0088] It should be understood that for this and other processes and methods disclosed herein, the flowcharts illustrate the functions and operations of one possible implementation of the present embodiment. As will be understood by those skilled in the art, alternative implementations are included within the scope of the exemplary embodiments of the present disclosure, where the functions can be performed in an order different from that shown or discussed, including substantially simultaneously or in the reverse order, depending on the functions involved.

[0089] At block 202, method 200 includes creating a plurality of circuits using implantable electrodes placed within a subject.

[0090] In some examples, creating a plurality of circuits using implantable electrodes placed within a subject includes creating a first circuit between a first implantable electrode and a second implantable electrode and creating a second circuit between the first implantable electrode and a third implantable electrode. In these examples, the first circuit and the second circuit have a common implantable electrode.

[0091] In some examples, creating a plurality of circuits using implantable electrodes placed within a subject includes creating a first circuit between a first implantable electrode and a second implantable electrode and creating a second circuit between a third implantable electrode and a fourth implantable electrode.

[0092] In some examples, creating multiple circuits using implantable electrodes placed within a subject includes creating a first circuit and a second circuit using implantable electrodes on a single lead. The single lead includes a plurality of electrodes arranged as a linear electrode array, and method 200 may optionally include changing the selection of the first electrode in the first circuit on the single lead to change the longitudinal positioning of the beat signal. Additionally, method 200 may optionally include changing the longitudinal positioning of the beat signal by transforming the configuration of the first and second circuits operated between a plurality of electrodes in the linear electrode array.

[0093] In some examples, creating multiple circuits using implantable electrodes placed within a subject includes creating a first circuit using implantable electrodes on a first lead and creating a second circuit using implantable electrodes on a second lead.

[0094] At block 204, method 200 includes transmitting a signal at a first frequency through a first circuit of the plurality of circuits, and the first circuit generates a first electric field.

[0095] At block 206, method 200 includes transmitting a signal at a second frequency through a second circuit of the plurality of circuits, and the second circuit generates a second electric field. The implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and the first electric field and the second electric field interfere with each other in an overlapping region to generate a beat frequency signal.

[0096] In one example, the first lead and the second lead are placed in a substantially linear configuration that is generally end-to-end, where the distance measured perpendicular to the same axis between the first lead and the second lead is less than about 2 mm.

[0097] In one example, the implantable electrodes are independently controllable to be arranged as positive and negative electrode pairs for creating the first circuit and the second circuit.

[0098] In some examples, method 200 includes transmitting a signal at a first frequency (including transmitting a signal at a frequency between about 1,000 Hz and about 20,000 Hz) and transmitting a signal at a second frequency (including transmitting a signal at a frequency between about 1,000 Hz and about 20,000 Hz), where the first frequency is different from the second frequency. In some examples, the beat frequency signal has a frequency within a range greater than 0 Hz to about 5,000 Hz.

[0099] Figure 14 A flowchart of an example method 210 for electrically stimulating a subject in accordance with an example embodiment is shown.

[0100] In Figure 14 The method shown presents, for example, what can beFigure 1 The method of using the stimulator 100 shown, and examples of methods that can be performed by components of the stimulator 100, for example, in Figure 1 In some cases, the components of the stimulator 100 can be configured to perform functions such that the components are actually configured and structured (using hardware and / or software) to enable these executions. In other examples, such as when operating in a specific manner, the components of the device and / or system can be arranged to be adapted to, capable of, or suitable for performing functions. The method can include one or more operations, functions, or actions shown in one or more of blocks 212-214. Although these blocks are shown in sequence, these blocks can also be performed in parallel and / or in a different order than described herein. Additionally, based on the required implementation, the individual blocks can be combined into fewer blocks, split into additional blocks, and / or removed.

[0101] It should be understood that for this process and method and other processes and methods disclosed herein, the flow diagram illustrates the functions and operations of one possible implementation of this embodiment. As will be understood by those skilled in the art, alternative implementations are included within the scope of the exemplary embodiments of the present disclosure, where the various functions can be performed in an order different from that shown or discussed, including substantially simultaneously or in the reverse order, depending on the functions involved.

[0102] In block 212, the method 210 includes transmitting a signal of a first frequency through a first circuit created between a first pair of implantable electrodes placed within a subject, and the first circuit generates a first electric field.

[0103] In block 214, the method 210 includes transmitting a signal of a second frequency through a second circuit created between a second pair of implantable electrodes placed within a subject, and the second circuit generates a second electric field.

[0104] In the method 210, the first pair of implantable electrodes and the second pair of implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and the first electric field interferes with the second electric field in an overlapping region to generate a beat signal.

[0105] In some examples, the first pair of implantable electrodes and the second pair of implantable electrodes are arranged perpendicular to the longitudinal axis of the spinal cord to form the first circuit and the second circuit, and the first circuit and the second circuit are placed on the same axis.

[0106] In some examples, the first pair of implantable electrodes and the second pair of implantable electrodes are included on a single lead, and the first pair of implantable electrodes and the second pair of implantable electrodes are independently controllable to be arranged as positive and negative electrode pairs for creating a first circuit and a second circuit. In some examples, the single lead includes a plurality of electrodes arranged as a linear electrode array, and method 210 further includes changing the selection of the first electrode in the first pair of implantable electrodes on the single lead to change the longitudinal positioning of the beat signal.

[0107] In some examples, the first pair of implantable electrodes is included on a first lead, the second pair of implantable electrodes is included on a second lead, and the first lead and the second lead are placed in a generally end-to-end substantially linear configuration such that the distance (d) measured perpendicular to the same axis between the first lead and the second lead is less than about 2 mm.

[0108] In some examples, the generally end-to-end substantially linear configuration includes at least one electrode on the first lead placed adjacent to at least one electrode on the second lead.

[0109] In some examples, method 210 includes transmitting the signal at a first frequency (including transmitting the signal at a frequency between about 1,000 Hz and about 20,000 Hz), and transmitting a signal at a second frequency (including transmitting the signal at a frequency between about 1,000 Hz and about 20,000 Hz), wherein the first frequency is different from the second frequency. In some examples, the beat signal has a frequency within a range greater than 0 Hz to about 5,000 Hz.

[0110] The electrical stimulation described herein can be used for a variety of different types of treatments or applications. In one example, the method described herein includes placing the first pair of implantable electrodes against the dura mater in the epidural space adjacent to the spinal cord of a subject, and placing the second pair of implantable electrodes against the dura mater in the epidural space adjacent to the spinal cord of the subject to provide spinal stimulation therapy. In such an example, the first pair of implantable electrodes and the second pair of implantable electrodes are arranged perpendicular to the longitudinal axis of the spinal cord to form a first circuit and a second circuit, and the first circuit and the second circuit are placed on the same axis.

[0111] There are also other exemplary applications, and the implantable electrodes can be placed accordingly, such as near the spinal cord and supporting tissues (such as glial cells and microglial cells, interstitial tissues, etc.), separate or simultaneous transforaminal stimulation of (one or more) spinal nerves and (one or more) spinal nerve roots and supporting tissues, vertebrae nerves and supporting tissues, peripheral nerves and supporting tissues, and the vagus nerve and supporting tissues. Other exemplary applications include treatment and application to sympathetic and parasympathetic nerves outside the spinal canal, which can be achieved by placing the implantable electrodes at paravertebral positions, such as the neck (including the superior cervical ganglion, middle cervical ganglion, cervicothoracic ganglion (stellate ganglion)), chest, and lumbar region, or prevertebral positions, such as the celiac, superior mesenteric, inferior mesenteric, and ganglion impar, etc.

[0112] Exemplary indications and intended uses of electrical stimulation include pain treatment (including chronic and acute), blood pressure regulation, blood glucose level regulation (diabetes regulation), inflammation, heart rate and cardiac nerve regulation, respiratory nerve regulation, nerve regulation of other vegetative functions (sympathetic and parasympathetic nervous systems), and anxiety.

[0113] Thus, in the exemplary methods described herein, the method optionally includes placing the implantable electrode into the space near the neural tissue of the subject, placing the implantable electrode into the space near the vertebral nerves of the subject, placing the implantable electrode into the space near the dorsal root ganglion of the subject, placing the first pair and the second pair of implantable electrodes into the space near the vagus nerve of the subject, or placing the implantable electrode into the space near the sympathetic and parasympathetic nerves.

[0114] In a further example, the systems and methods described herein are useful for operating an electrical stimulator and programming the operation of the electrical stimulator 100. To program the electrical stimulator 100 and select the electrodes to be used from the implantable electrodes 108, a circuit is created (such as the method described in reference Figure 13 or Figure 14 ), and the subject can indicate the location on their body where they physically feel the stimulation. In this way, the stimulation can be moved left / right or up / down by changing the electrodes selected from the implantable electrodes 108, so as to provide the stimulation to the desired area.

[0115] By the terms "about" and / or the term "substantially", it is meant that the stated features, parameters, or values need not be achieved exactly, but include deviations or variations such as tolerances, measurement errors, measurement accuracy limitations, and other factors known to those skilled in the art that may occur in an amount that does not impede the effect expected to be provided by the feature.

[0116] It should be emphasized that the above-described embodiments of the present disclosure are merely exemplary possible implementation manners proposed for clear understanding. Many variations and modifications can be made to the above (one or more) embodiments without materially departing from the principles of the present disclosure. All such modifications and variations are intended to be included within the scope of the present disclosure.

Claims

1. A method for electrically stimulating a subject, the method comprises: creating a plurality of circuits using implantable electrodes placed within the subject; transmitting a signal of a first frequency through a first circuit of the plurality of circuits, wherein the first circuit generates a first electric field; transmitting a signal of a second frequency through a second circuit of the plurality of circuits, wherein the second circuit generates a second electric field, wherein the implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and wherein the first electric field interferes with the second electric field in an overlapping region to generate a beat signal.

2. The method according to claim 1, wherein creating a plurality of circuits using implantable electrodes placed within the subject comprises: creating the first circuit between a first implantable electrode and a second implantable electrode; and creating the second circuit between the first implantable electrode and a third implantable electrode, wherein the first circuit and the second circuit have a common implantable electrode.

3. The method according to claim 1, wherein creating a plurality of circuits using implantable electrodes placed within the subject comprises: creating the first circuit between a first implantable electrode and a second implantable electrode; and creating the second circuit between a third implantable electrode and a fourth implantable electrode.

4. The method according to claim 1, wherein creating a plurality of circuits using implantable electrodes placed within the subject comprises: creating the first circuit and the second circuit using implantable electrodes on a single lead.

5. The method according to claim 4, wherein the single lead comprises a plurality of electrodes arranged as a linear electrode array, and the method further comprises: changing the selection of the first electrode in the first circuit on the single lead to change the longitudinal positioning of the beat signal.

6. The method according to claim 4, wherein the single lead comprises a plurality of electrodes arranged as a linear electrode array, and the method further comprises: changing the longitudinal positioning of the beat signal by transforming the configuration of the first circuit and the second circuit to be operated between the plurality of electrodes in the linear electrode array.

7. The method according to claim 1, wherein implantable electrodes are provided on a first lead and a second lead, and wherein creating a plurality of circuits using implantable electrodes placed within the subject comprises: creating the first circuit using the implantable electrodes on the first lead; and creating the second circuit using the implantable electrodes on the second lead.

8. The method according to claim 7, wherein the first lead and the second lead are placed in the substantially linear configuration in a substantially end-to-end manner, wherein the distance measured perpendicular to the same axis between the first lead and the second lead is less than about 2 mm.

9. The method according to claim 1, wherein the implantable electrodes are independently controllable to be arranged as positive and negative electrode pairs for creating the first circuit and the second circuit.

10. The method according to claim 1, wherein: Transmitting the signal of the first frequency includes transmitting the signal at a frequency between approximately 1,000 Hz and approximately 20,000 Hz; and Transmitting the signal of the second frequency includes transmitting the signal at a frequency between approximately 1,000 Hz and approximately 20,000 Hz, wherein the first frequency is different from the second frequency.

11. The method according to claim 1, wherein the beat signal has a frequency within a range greater than 0 Hz to approximately 5,000 Hz.

12. The method according to claim 1, further comprising: Placing the implantable electrode into a space adjacent to the nerve tissue of the subject.

13. The method according to claim 1, further comprising: Placing the implantable electrode into a space adjacent to the vertebral nerve of the subject.

14. The method according to claim 1, further comprising: Placing the implantable electrode into a space adjacent to the spinal nerve and spinal nerve root of the subject.

15. The method according to claim 1, further comprising: Placing the implantable electrode into a space adjacent to the vagus nerve of the subject.

16. The method according to claim 1, further comprising: Placing the implantable electrode into a space adjacent to the sympathetic and parasympathetic nerves.

17. A method of electrically stimulating a subject, the method comprising: Transmitting a signal of a first frequency through a first circuit created between a first pair of implantable electrodes placed within the subject, wherein the first circuit generates a first electric field; Transmitting a signal of a second frequency through a second circuit created between a second pair of implantable electrodes placed within the subject, wherein the second circuit generates a second electric field; wherein the first pair of implantable electrodes and the second pair of implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field and the second electric field are in an axially offset configuration, and wherein the first electric field and the second electric field interfere with each other in an overlapping region to generate a beat signal.

18. The method according to claim 17, wherein the first pair of implantable electrodes and the second pair of implantable electrodes are arranged perpendicular to the longitudinal axis of the spinal cord to form the first circuit and the second circuit, and the first circuit and the second circuit are placed on the same axis.

19. The method according to claim 17, wherein the first pair of implantable electrodes and the second pair of implantable electrodes are included in a single lead, wherein the first pair of implantable electrodes and the second pair of implantable electrodes are independently controllable to be arranged as positive and negative electrode pairs for creating the first circuit and the second circuit.

20. The method according to claim 19, wherein the single lead includes a plurality of electrodes arranged as a linear electrode array, and the method further comprising: Changing the selection of the first electrode in the first pair of implantable electrodes on the single lead to change the longitudinal position of the beat signal.

21. The method according to claim 17, wherein the first pair of implantable electrodes is included in a first lead, and the second pair of implantable electrodes is included in a second lead, wherein the first lead and the second lead are placed in the substantially linear configuration in a substantially end-to-end manner, and a distance measured perpendicular to the same axis between the first lead and the second lead is less than about 2 mm.

22. The method according to claim 17, wherein the substantially end-to-end substantially linear configuration includes at least one electrode on the first lead placed adjacent to at least one electrode on the second lead.

23. The method according to claim 17, wherein: transmitting the signal of the first frequency includes transmitting the signal at a frequency between about 1,000 Hz and about 20,000 Hz; and transmitting the signal of the second frequency includes transmitting the signal at a frequency between about 1,000 Hz and about 20,000 Hz, wherein the first frequency is different from the second frequency.

24. The method according to claim 17, wherein the beat signal has a frequency within a range greater than 0 Hz to about 5,000 Hz.

25. The method according to claim 17, further comprising: placing the first pair of implantable electrodes onto the dura mater in the epidural space near the spinal cord of the subject; and placing the second pair of implantable electrodes onto the dura mater in the epidural space near the spinal cord of the subject.

26. The method according to claim 17, further comprising: placing the first pair of implantable electrodes and placing the second pair of implantable electrodes into a space near the nerve tissue of the subject.

27. The method according to claim 17, further comprising: placing the first pair of implantable electrodes and placing the second pair of implantable electrodes into a space near the vertebral nerve of the subject.

28. The method according to claim 17, further comprising: placing the first pair of implantable electrodes and placing the second pair of implantable electrodes into a space near the spinal nerve and spinal nerve root of the subject.

29. The method according to claim 17, further comprising: placing the first pair of implantable electrodes and placing the second pair of implantable electrodes into a space near the vagus nerve of the subject.

30. An electrical stimulator for electrically stimulating a subject, comprising: an interference current generator that generates an interference alternating current output including a first signal and a second signal; and a plurality of circuits created using implantable electrodes, wherein the implantable electrodes have a first end and a second end, wherein the first end is coupled to the interference current generator, and the second end is configured to be placed in the subject's body; wherein the first signal is transmitted through a first circuit of the plurality of circuits to generate a first electric field, wherein the second signal is transmitted through a second circuit of the plurality of circuits to generate a second electric field, wherein the implantable electrodes are placed in a substantially linear configuration along the same axis such that the first electric field of the first circuit and the second electric field of the second circuit are in an axially offset configuration, and wherein the first electric field interferes with the second electric field in an overlapping region to generate a beat signal.

31. The electrical stimulator of claim 30, wherein the implantable electrodes include a first pair of implantable electrodes and a second pair of implantable electrodes placed in the substantially linear configuration along the same axis.

32. The electrical stimulator of claim 30, wherein the plurality of circuits includes the first circuit between the first implantable electrode and the second implantable electrode, and the second circuit between the first implantable electrode and the third implantable electrode, wherein the first circuit and the second circuit have a common implantable electrode.

33. The electrical stimulator of claim 30, wherein the implantable electrodes are included on a single lead, and wherein the implantable electrodes are independently controllable to be arranged as positive and negative electrode pairs for creating the first circuit and the second circuit.

34. The electrical stimulator of claim 30, wherein the implantable electrodes are included on a first lead and a second lead, wherein the first lead and the second lead are placed in the substantially linear configuration in a substantially end-to-end manner, and wherein the distance measured perpendicular to the same axis between the first lead and the second lead is less than about 2 mm.

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