Electrostimulator

Abstract

To prevent habituation to electrical stimulation and provide better promotion of motor function of an activation object and improvement effect.SOLUTION: An electrostimulator includes: a stimulation electrode part including one or more pairs of electrodes to be fitted to the skin of a living body; and a stimulation voltage application part for outputting a stimulation voltage signal to the stimulation electrode part. The stimulation voltage signal has a signal waveform in which a stimulation period of applying a stimulation voltage to a living body and a stop period of not applying a stimulation voltage are alternately generated. The stimulation period has a signal waveform that is a rectangular wave of switching an application direction of a stimulation voltage in both directions periodically. The stop period is determined on the basis of a frequency that is selected in a random manner with a probability according to a gaussian probability distribution that uses a prescribed frequency as the median value for each generation of a stop period.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrical stimulation device. [Background technology]

[0002] Conventionally, various stimulation devices for promoting swallowing function have been proposed (see, for example, Patent Documents 1 and 2). Patent Document 1 proposes an electrical stimulation treatment device for swallowing disorders that sequentially stimulates the swallowing muscles of a user according to a preset muscle activation sequence. Patent Document 2 discloses a stimulation device that applies transcutaneous electrical stimulation with a high-frequency carrier signal superimposed to a region of the spinal cord (cervical spinal cord and / or thoracic spinal cord and / or lumbar spinal cord or these regions) to promote swallowing. In the stimulation device described in Patent Document 2, the user can control one or more parameters of the stimulation frequency, stimulation amplitude, stimulation pulse width, and carrier frequency amplitude in the signal for transcutaneous electrical stimulation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-016678 A [Patent Document 2] JP 2023-055798 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, in the stimulation device disclosed in Patent Document 2, the parameters of the signal for transcutaneous electrical stimulation can be set appropriately, but after the parameters are set, the same stimulation pattern signal is provided to the user, so that the effect may weaken due to, for example, habituation to the stimulation.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electrical stimulation device that can prevent habituation to electrical stimulation and achieve better promotion and improvement of the motor function of the subject to be activated. [Means for solving the problem]

[0006] In order to solve the above problems, the electrical stimulation device of the present invention comprises a stimulation electrode section which is attached to the skin of a living body and includes one or more pairs of electrodes to which a stimulation voltage is applied, and a stimulation voltage application section which outputs a stimulation voltage signal to the stimulation electrode section, and the signal waveform of the stimulation voltage signal is a waveform in which a stimulation period in which a stimulation voltage is applied to the living body and a stop period in which the stimulation voltage is not applied to the living body occur alternately and repeatedly, the signal waveform of the stimulation period is a rectangular wave which periodically switches the application direction of the stimulation voltage in both directions, and the stop period is determined each time a stop period occurs based on a frequency randomly selected with a probability according to a Gaussian probability distribution with a predetermined frequency as a median. Effect of the Invention

[0007] According to the electrical stimulation device of the present invention having the above-mentioned configuration, it is possible to prevent habituation to electrical stimulation and to obtain a better promotion and improvement effect of the motor function of the activation target. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram of an electrical stimulation device according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing an example of a waveform of an electrical stimulation signal generated by an electrical stimulation device according to an embodiment of the present invention; [Diagram 3] FIG. 1 illustrates a Gaussian probability distribution used to determine stimulation pause periods in an electrical stimulation signal generated by an electrical stimulation device according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram for explaining an example of electrical stimulation by an electrical stimulation device according to one embodiment of the present invention. [Diagram 5]FIG. 2 is a diagram showing the results (part 1) of an example of electrical stimulation using an electrical stimulation device according to one embodiment of the present invention. [Figure 6] FIG. 11 is a diagram showing the results (part 2) of an example of electrical stimulation using an electrical stimulation device according to one embodiment of the present invention. [Figure 7] 1A to 1C are diagrams illustrating an example of application of an electrical stimulation device according to an embodiment of the present invention to a human body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an electrical stimulation device according to an embodiment of the present invention will be specifically described with reference to the drawings. In this embodiment, an electrical stimulation device intended to activate (promote) swallowing movement (function) will be described as an example.

[0010] [Configuration of electrical stimulation device] Fig. 1 is a block diagram of an electrical stimulation device 10 according to the present embodiment. As shown in Fig. 1, the electrical stimulation device 10 includes an electrical stimulation device main body 1 (stimulation voltage application section) and a surface electrode section 2. The electrical stimulation device main body 1 includes a microcomputer 11, a biphasic signal generator 12, a DC (Direct Current) / DC converter 13, a mobile battery 14, an operation section 15, and a display section 16. The surface electrode section 2 includes two or more surface electrodes, and includes four surface electrodes 3a, 3b, 4a, and 4b in this embodiment. The surface electrodes are the same size.

[0011] In the electrical stimulation device 10, the microcomputer 11 is connected to a biphasic signal generator 12, an operation unit 15, and a display unit 16. The biphasic signal generator 12 is connected to a DC / DC converter 13 and each of the surface electrodes in the surface electrode unit 2. In addition, the DC / DC converter 13 is connected to a mobile battery 14.

[0012] In this embodiment, when each surface electrode is attached to the surface of the skin of a living body to provide electrical stimulation, a stimulation current is passed between the surface electrode 3a (first electrode) and the surface electrode 3b (second electrode) and between the surface electrode 4a and the surface electrode 4b. Therefore, the surface electrode 3a and the surface electrode 3b constitute one stimulation electrode section (hereinafter referred to as the "first stimulation electrode section 3"), and the surface electrode 4a and the surface electrode 4b constitute another stimulation electrode section (hereinafter referred to as the "second stimulation electrode section 4").

[0013] [Configuration and operation of each component of the electrical stimulation device main body] The microcomputer 11 is composed of a microprocessor including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and functions as an arithmetic processing device and a control device, controlling the operation of each part of the electrical stimulation device 10. For example, the generation of a stimulation pattern of an electrical stimulation signal described below by the biphasic signal generator 12 and the control of the output process are performed based on a control signal output from the microcomputer 11 to the biphasic signal generator 12.

[0014] The biphasic signal generator 12 generates a stimulation voltage signal using a direct current voltage input from the DC / DC converter 13, and outputs the generated stimulation voltage signal to the surface electrode unit 2. In this embodiment, a rectangular wave periodic signal (hereinafter referred to as a "biphasic pulse voltage signal") with a specific frequency fc having a rectangular wave as one period in which the stimulation voltage value is constant at +V for a predetermined period and then constant at -V for the same period as the period in which the stimulation voltage value is +V is generated as the stimulation voltage signal. In this embodiment, as shown in FIG. 1, the biphasic signal generator 12 generates a biphasic pulse voltage signal 30a to be applied between the surface electrodes 3a and 3b (a pair of electrodes) constituting the first stimulation electrode unit 3, and a biphasic pulse voltage signal 40a to be applied between the surface electrodes 4a and 4b (a pair of electrodes) constituting the second stimulation electrode unit 4. In this embodiment, the signal waveform of the biphasic pulse voltage signal 30a output to the first stimulating electrode section 3 is the same as that of the biphasic pulse voltage signal 40a output to the second stimulating electrode section 4.

[0015] In this embodiment, information on the frequency of the biphasic pulse voltage signal output from the biphasic signal generator 12 to each stimulation electrode unit is included in a control signal input from the microcomputer 11. That is, the specific frequency fc of the biphasic pulse voltage signal generated by the biphasic signal generator 12 is set by the control signal input from the microcomputer 11. Also, the absolute value of the amplitude value of the biphasic pulse voltage signal is the value of the direct current voltage input from the DC / DC converter 13. That is, the stimulation voltage value (±V) of the biphasic pulse voltage signal generated by the biphasic signal generator 12 is set by the DC / DC converter 13. Note that the method of generating the biphasic pulse voltage signal is not limited to this example, and any method can be used as long as it is a method capable of generating a similar rectangular wave periodic signal.

[0016] When the biphasic pulse voltage signal 30a having the above configuration is applied to the surface electrodes 3a and 3b constituting the first stimulation electrode unit 3, the voltage and current applied between the two surface electrodes is as follows: Here, the voltage application direction from the surface electrode 3a to the surface electrode 3b is defined as the positive direction.

[0017] When the biphasic pulse voltage signal 30a is applied between the surface electrode 3a and the surface electrode 3b attached to the living body, a stimulation voltage value of +V is first applied between the surface electrode 3a and the surface electrode 3b for a predetermined period. During this period, the surface electrode 3a becomes the positive electrode and the surface electrode 3b becomes the negative electrode, so that the stimulation voltage is applied in the direction from the surface electrode 3a to the surface electrode 3b, and the stimulation current 30b flows from the surface electrode 3a to the surface electrode 3b through the living body. After that, when the stimulation voltage value is switched to -V, a stimulation voltage value of -V is applied between the surface electrode 3a and the surface electrode 3b for a predetermined period. During this period, the surface electrode 3a becomes the negative electrode and the surface electrode 3b becomes the positive electrode, so that the stimulation voltage is applied in the direction from the surface electrode 3b to the surface electrode 3a, and the stimulation current 30b flows from the surface electrode 3b to the surface electrode 3a through the living body. In other words, when a biphasic pulse voltage signal 30a is applied between surface electrodes 3a and 3b attached to a living body, the direction of application of the stimulation voltage between surface electrodes 3a and 3b periodically switches in both directions, and the direction of stimulation current 30b also periodically switches in both directions (see Figure 1).

[0018] Similarly, when the biphasic pulse voltage signal 40a is applied between the surface electrodes 4a and 4b attached to the living body, a stimulation voltage value of +V is first applied between the surface electrodes 4a and 4b for a predetermined period, and during this period, a stimulation current 40b flows from the surface electrode 4a to the surface electrode 4b through the living body. After that, the stimulation voltage value is switched to -V, and a stimulation voltage value of -V is applied between the surface electrodes 4a and 4b for a predetermined period, and during this period, the stimulation current 40b flows from the surface electrode 4b to the surface electrode 4a through the living body. That is, when the biphasic pulse voltage signal 40a is applied between the surface electrodes 4a and 4b attached to the living body, the application direction of the stimulation voltage is periodically switched between two directions between the surface electrodes 4a and 4b, and the direction of the stimulation current 40b is also periodically switched between two directions (see FIG. 1).

[0019] In this embodiment, the electrical stimulation signal given to the living body from the biphasic signal generator 12 via the first stimulation electrode unit 3 and the second stimulation electrode unit 4 is composed of a period during which the biphasic pulse voltage signal is generated and a period during which the biphasic pulse voltage signal is stopped, the details of which will be described later with reference to the drawings. The output start timing and output stop timing of the biphasic pulse voltage signals 30a, 40a to each stimulation electrode unit by the biphasic signal generator 12 are controlled by a control signal input from the microcomputer 11.

[0020] The DC / DC converter 13 converts the DC voltage input from the mobile battery 14 into a stimulation voltage (DC) of a predetermined value. In this embodiment, the mobile battery 14 has a DC voltage of 5V. In this embodiment, a converter capable of not only stepping down but also stepping up the DC voltage (5V) input from the mobile battery 14 is used as the DC / DC converter 13. In other words, the DC / DC converter 13 can convert the DC voltage (5V) input from the mobile battery 14 into various DC voltages.

[0021] Usually, the optimal stimulation voltage (stimulation current) varies depending on the living body (user) to be stimulated and the stimulation location, but it is possible to respond to these various situations by using a variable output DC / DC converter 13. The DC voltage value converted by DC / DC converter 13 may be changed (adjusted) by, for example, an operator of electrical stimulation device 10 manually operating an adjustment mechanism (not shown) provided in DC / DC converter 13. Also, for example, a control signal including information on the stimulation voltage may be input from microcomputer 11 to DC / DC converter 13, and DC / DC converter 13 may automatically adjust the DC voltage value based on the control signal.

[0022] Operation unit 15 is composed of, for example, keys and buttons, and generates an operation signal according to the operation content input by an operator of electrical stimulation device 10, and outputs the operation signal to microcomputer 11 (CPU). Therefore, for example, various setting conditions for electrical stimulation can be set by an operation input to operation unit 15 by the operator, etc.

[0023] Display unit 16 is, for example, a liquid crystal panel, and displays characters, images, and the like on a screen. Display unit 16 can display various information, such as various setting conditions for electrical stimulation and the status (elapsed time, etc.) during execution of electrical stimulation. Display unit 16 may be configured as a touch panel, in which case display unit 16 and operation unit 15 are configured integrally.

[0024] [Configuration of electrical stimulation signal] Next, a description will be given of the configuration of the electrical stimulation signal provided to the living body from the biphasic signal generator 12 via each stimulation electrode unit in the electrical stimulation device 10 of this embodiment. Fig. 2 is a diagram showing an example of the waveform of the electrical stimulation signal generated by the electrical stimulation device 10, where the horizontal axis indicates time and the vertical axis indicates voltage value.

[0025] In order to omit the explanation, the electrical stimulation signal 31 output from the first stimulation electrode section 3 composed of the surface electrodes 3a and 3b will be explained. The configuration of the electrical stimulation signal output from the second stimulation electrode section 4 composed of the surface electrodes 4a and 4b is similar to that of the electrical stimulation signal 31 output from the first stimulation electrode section 3, so the explanation thereof will be omitted here.

[0026] As shown in Fig. 2, the electrical stimulation signal 31 output from the first stimulation electrode unit 3 is composed of a period during which the biphasic pulse voltage signal 30a is generated and a period during which the biphasic pulse voltage signal 30a is stopped, and the electrical stimulation signal 31 alternately generates both periods. That is, the electrical stimulation signal 31 has a waveform, so-called a burst waveform, in which a period during which the biphasic pulse voltage signal 30a is generated and a period during which the biphasic pulse voltage signal 30a is not generated are alternately repeated on the time axis. Therefore, hereinafter, the period during which the biphasic pulse voltage signal 30a is generated is referred to as a "burst oscillation period", and the period during which the biphasic pulse voltage signal 30a is stopped is referred to as a "burst stop period".

[0027] In the example shown in FIG. 2, the burst oscillation period (stimulation period) of the electrical stimulation signal 31 is "tp", and the burst stop period (stop period) is "tn". The absolute value of the voltage amplitude value of the biphasic pulse voltage signal 30a is "V", and one cycle period of the biphasic pulse voltage signal 30a is "tc" (the reciprocal of the specific frequency fc). The burst oscillation period tp of the electrical stimulation signal 31 is a period (tp=k×tc) of k cycles (three cycles in the example shown in FIG. 2) of the biphasic pulse voltage signal 30a. These parameters of the electrical stimulation signal 31 are constant values ​​set in advance. Among these parameters, the parameters other than the absolute value V of the voltage amplitude value of the biphasic pulse voltage signal 30a are set by the microcomputer 11 as described above, but the absolute value V of the voltage amplitude value of the biphasic pulse voltage signal 30a is set by the DC / DC converter 13.

[0028] In this embodiment, the burst stop period tn is randomly determined each time the burst stop period occurs. That is, the burst stop period tn is a variable parameter. The burst stop period tn is determined (set) by the microcomputer 11, and specifically, the burst stop period tn is determined as follows.

[0029] First, a predetermined frequency (hereinafter referred to as "average occurrence frequency of burst stimulation") f0 corresponding to the average occurrence frequency of the burst oscillation period tp (electrical stimulation period) is set. Next, a Gaussian probability distribution with the average occurrence frequency f0 of the burst stimulation as the median is set. FIG. 3 is a diagram showing a Gaussian probability distribution with the average occurrence frequency f0 of the burst stimulation as the median. Note that the variance of the Gaussian probability distribution with the average occurrence frequency f0 of the burst stimulation as the median can be set appropriately. Then, a frequency fn is randomly selected according to the probability defined by the Gaussian probability distribution shown in FIG. 3, and the reciprocal of the selected frequency fn is determined (set) as the burst stop period tn (=1 / fn).

[0030] In this embodiment, the burst stop period tn is determined (set) at the start of the burst oscillation period tp. The burst stop period tn determined at the start of the burst oscillation period tp occurs after the burst oscillation period tp. That is, the burst stop period tn to be generated after the burst oscillation period tp is determined at each start of the burst oscillation period tp. As a result, one cycle period of the electrical stimulation signal 31, which is composed of one burst oscillation period tp and one subsequent burst stop period tn, changes randomly over time.

[0031] When the burst stop period tn is randomly determined as described above, the occurrence interval of the burst oscillation period tp (electrical stimulation period) in the electrical stimulation signal 31 changes randomly according to the probability defined by the Gaussian probability distribution with the average occurrence frequency f0 of the burst stimulation as the median value. Therefore, in this case, the electrical stimulation pattern given to the living body can be changed randomly over time, and habituation to the stimulation can be suppressed.

[0032] [Example of electrical stimulation] Next, an example (Example) in which the electrical stimulation device 10 of the present embodiment was actually applied to an adult rat will be specifically described. In the Example, an electrical stimulation experiment was performed on the adult rat to examine changes in swallowing movement due to electrical stimulation.

[0033] (1) Various settings for electrical stimulation experiments 4A and 4B are diagrams showing how the surface electrodes of the electrical stimulation device 10 are attached in the embodiment. In the embodiment, as shown in Fig. 4A, the surface electrodes 3a and 3b constituting the first stimulation electrode unit 3 are attached to predetermined positions on the skin of the back of an adult rat, specifically, to positions corresponding to T9 to T10 of the thoracic vertebrae (hatched portions in the figure). In this case, the surface electrodes 3a and 3b are attached at positions such that the thoracic vertebrae T9 to T10 are sandwiched between the surface electrodes 3a and 3b.

[0034] In the embodiment, as shown in FIG. 4B, the surface electrodes 4a and 4b constituting the second stimulating electrode unit 4 were attached to the skin of the neck of an adult rat. At this time, the surface electrodes 4a and 4b were attached at a position where the neck was sandwiched between the surface electrodes 4a and 4b. Furthermore, although not shown in the drawings, in the embodiment, needle electrodes were inserted into each of the mylohyoid muscle (larynx elevator muscle), thyroarytenoid muscle (larynx adductor muscle), and thyropharyngeal muscle (pharyngeal constrictor muscle) which are muscle groups involved in the swallowing movement of an adult rat (hereinafter referred to as "swallowing-related muscles"), in order to measure electromyograms (muscle potentials) during swallowing.

[0035] In the embodiment, the one cycle period tc of the biphasic pulse voltage signal 30a applied during the burst oscillation period tp of the electrical stimulation signal 31 was set to 300 μS. That is, the specific frequency fc of the biphasic pulse voltage signal 30a was set to about 3.33 kHz (= 1 / 300 μS). The burst oscillation period tp of the biphasic pulse voltage signal 30a was set to a period of 50 cycles of the biphasic pulse voltage signal 30a (300 μS × 50), and the absolute value V of the amplitude value of the biphasic pulse voltage signal 30a was set to 2 V. In addition, the average occurrence frequency f0 of the burst stimulation for randomly determining the burst stop period tn (the median value of the Gaussian probability distribution) was set to 30 Hz or 300 Hz.

[0036] (2) Various stimulation experiments In the embodiment, the surface electrodes and needle electrodes of the electrical stimulation device 10 were attached to an adult rat as described above, and various parameters of the electrical stimulation were set, and then the following stimulation experiments A to D were performed. In each of the following stimulation experiments A to D, the stimulation experiment was performed on four adult rats. Note that the four adult rats used in each of the following stimulation experiments A to D were different for each stimulation experiment.

[0037] In the stimulation experiment A, the average frequency f0 of the burst stimulation for randomly determining the burst stop period tn was set to 30 Hz. In the stimulation experiment A, first, three experiments were performed in which electrical stimulation was applied only to the neck for 120 seconds (Experiments S1A to S3A), and then three experiments were performed in which electrical stimulation was applied simultaneously to both the back and neck for 120 seconds (Experiments S4A to S6A).

[0038] In the stimulation experiment B, the average frequency f0 of the burst stimulation for randomly determining the burst stop period tn was set to 30 Hz. In the stimulation experiment B, first, three experiments were performed in which electrical stimulation was applied only to the back for 120 seconds (Experiments S1B to S3B), and then three experiments were performed in which electrical stimulation was applied simultaneously to both the back and the neck for 120 seconds (Experiments S4B to S6B).

[0039] In the stimulation experiment C, the average frequency f0 of the burst stimulation for randomly determining the burst stop period tn was set to 300 Hz. In the stimulation experiment C, first, three experiments were performed in which electrical stimulation was applied only to the neck for 120 seconds (Experiments S1C to S3C), and then three experiments were performed in which electrical stimulation was applied simultaneously to both the back and neck for 120 seconds (Experiments S4C to S6C).

[0040] In the stimulation experiment D, the average frequency f0 of the burst stimulation for randomly determining the burst stop period tn was set to 300 Hz. In the stimulation experiment D, first, three experiments were performed in which electrical stimulation was applied only to the back for 120 seconds (Experiments S1D ​​to S3D), and then three experiments were performed in which electrical stimulation was applied simultaneously to both the back and neck for 120 seconds (Experiments S4D to S6D).

[0041] In each of the stimulation experiments A to D, the amplitude of the mylohyoid, thyroarytenoid, and thyropharyngeal myoelectric potentials measured after experiments S1N to S6N (N=A to D) was compared with those measured before stimulation (S0A to S0D). In the stimulation experiments A to D, the stimulation current flowing from each surface electrode into the skin during stimulation was 3.5 mA or less, which was a lower current value than, for example, the current value that would stimulate a muscle directly.

[0042] (3) Measurement results of myoelectric change rate 5A and 5B are graphs showing the experimental results of stimulation experiments A and B, respectively, and FIG. 6A and 6B are graphs showing the experimental results of stimulation experiments C and D, respectively. In each graph, the horizontal axis indicates the type of pre-stimulation S0N and experiments S1N to S6N (N=A to D), and the vertical axis indicates the myoelectric change rate (%) obtained in each experiment. The myoelectric change rate is the value obtained by dividing the amplitude value of the myoelectric potential measured in each of experiments S1N to S6N (N=A to D) by the amplitude value of the myoelectric potential measured in pre-stimulation S0N, and multiplying the result by 100. Therefore, in each graph of FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B, the myoelectric change rate of pre-stimulation S0N (N=A to D) is 100%, regardless of the type of muscle. In addition, the characteristics of the dotted lines in each graph of Figures 5A, 5B, 6A, and 6B represent the change characteristics of the mylohyoid muscle's mylohyoid change rate, the characteristics of the dashed lines represent the change characteristics of the mylohyoid muscle's mylohyoid change rate, and the characteristics of the solid lines represent the change characteristics of the mylohyoid muscle's mylohyoid change rate.

[0043] From the graphs shown in Figures 5A, 5B, 6A and 6B, it was found that the maximum amplitude of the myoelectric potential was larger when both the back and the neck were stimulated at the same time than when either the back or the neck was stimulated. It was also found that the amplitude of the myoelectric potential (myoelectric change rate) was larger when the average occurrence frequency f0 (median value of Gaussian probability distribution) of the burst stimulation was set to 30 Hz than when it was set to 300 Hz. This suggests that the lower the average occurrence frequency of the burst oscillation period tp (electrical stimulation period), the more the swallowing pattern generator (CPG: Central Pattern Generator) that controls the swallowing movement and exists in the medulla oblongata is activated.

[0044] (4) Results of significance tests and post-hoc analyses Next, the results of the significance test and post-hoc analysis (post-hoc analysis) performed on the results of each of the above stimulation experiments A to D will be explained. In the significance test, f-value (data variance ratio) and p-value (significance probability) were calculated. In addition, p-value = 0.05 was adopted as the criterion for determining significance, and data of experimental items with p-values ​​of 0.05 or less were judged to be significant (significant results were obtained).

[0045] In stimulation experiment A, a significant result was obtained for the experimental results of the thyropharyngeal muscle (f value = 7.03, p value < 0.001) compared to before stimulation (S0A), and it was found that the stimulation form of stimulation experiment A had an effect on the amplitude of the myoelectric potential (myoelectric change rate) of the thyropharyngeal muscle. Specifically, the post-hoc analysis showed that the myoelectric change rate of the thyropharyngeal muscle significantly increased after experiments S4A to S6A, in which both the back and the neck were stimulated.

[0046] In the stimulation experiment B, significant results were obtained for the mylohyoid muscle experimental results (f value = 6.46, p value < 0.001) and the thyropharyngeal muscle experimental results (f value = 3.93, p value = 0.009) compared to before stimulation (S0B). That is, it was found that the stimulation mode of the stimulation experiment B had an effect on the amplitude (mylohyoid muscle and thyropharyngeal muscle myoelectric potential (myoelectric change rate) of the mylohyoid muscle. Specifically, as a result of the post-hoc analysis, it was found that the mylohyoid muscle myoelectric change rate increased significantly after the experiment S3B in which only the back was stimulated, and after the experiments S4B to S6B in which both the back and the neck were stimulated. It was also found that the thyropharyngeal muscle myoelectric change rate increased significantly after the experiments S1B to S3B in which only the back was stimulated, and after the experiments S4B to S6B in which both the back and the neck were stimulated.

[0047] In the stimulation experiment C, significant results were obtained for the mylohyoid muscle experimental results (f value = 3.89, p value = 0.009), the thyroarytenoid muscle experimental results (f value = 12.51, p value < 0.001), and the thyropharyngeal muscle experimental results (f value = 3.79, p value = 0.01) compared to before stimulation (S0C). That is, it was found that the stimulation mode of the stimulation experiment C affected the amplitude (myoelectric change rate) of the mylohyoid muscle, thyroarytenoid muscle, and thyropharyngeal muscle. Specifically, as a result of the post-hoc analysis, it was found that the mylohyoid muscle's myoelectric change rate increased significantly after the experiments S4C to S6C in which both the back and the neck were stimulated. It was found that the myoelectric change rate of the thyroarytenoid muscle increased significantly after the experiments S3C in which only the neck was stimulated, and after the experiments S4C to S6C in which both the back and the neck were stimulated. It was also found that the myoelectric change rate of the thyropharyngeal muscle increased significantly after experiment S3C, in which only the neck was stimulated, and after experiments S4C to S6C, in which both the back and neck were stimulated.

[0048] In the stimulation experiment D, significant results were obtained for the mylohyoid muscle experimental results (f value = 3.99, p value = 0.008), the thyroarytenoid muscle experimental results (f value = 4.83, p value = 0.003), and the thyropharyngeal muscle experimental results (f value = 6.35, p value < 0.001) compared to before stimulation (S0D). That is, it was found that the stimulation mode of the stimulation experiment D had an effect on the amplitude (myoelectric change rate) of the mylohyoid muscle, thyroarytenoid muscle, and thyropharyngeal muscle. Specifically, as a result of the post-hoc analysis, it was found that the mylohyoid muscle's myoelectric change rate increased significantly after the experiments S4D to S6D in which both the back and the neck were stimulated. It was found that the myoelectric change rate of the thyroarytenoid muscle increased significantly after the experiments S3D in which only the back was stimulated, and after the experiments S4D to S6D in which both the back and the neck were stimulated. In addition, it was found that the myoelectric change rate of the thyropharyngeal muscle increased significantly after experiments S2D to S3D, in which only the back was stimulated, and after experiments S4D to S6D, in which both the back and neck were stimulated. In stimulation experiment D, the significance test for the thyropharyngeal muscle compared to experiment S1D gave a p-value of 0.058, which is close to the significance criterion (p-value = 0.05).

[0049] (5) Overall rating Comprehensive evaluation of the above-mentioned measurement results of the myoelectric change rate, as well as the results of the significance test and post-hoc analysis, revealed the following effects: First, whether the average occurrence frequency f0 of the burst stimulation in the electrical stimulation signal 31 is 30 Hz or 300 Hz, simultaneous stimulation of both the back and neck increases the amplitude of the mylohyoid, thyroarytenoid, and thyropharyngeal muscles.

[0050] Furthermore, it was found that when only the back was stimulated, the myoelectric change rate of the swallowing-related muscles increased significantly with early stimulation compared to when only the neck was stimulated, regardless of whether the average occurrence frequency f0 of the burst stimulation in the electrical stimulation signal 31 was 30 Hz or 300 Hz.

[0051] Specifically, when the average frequency f0 of burst stimulation is 30Hz and only the back is stimulated, the myoelectric change rate of the mylohyoid muscle and the thyropharyngeal muscle increases significantly. When the average frequency f0 of burst stimulation is 300Hz and only the back is stimulated, the myoelectric change rate of the thyroarytenoid muscle and the thyropharyngeal muscle increases significantly. On the other hand, when the average frequency f0 of burst stimulation is 300Hz and only the neck is stimulated, the myoelectric change rate of the thyroarytenoid muscle and the thyropharyngeal muscle increases significantly. From these results, in the embodiment, when the surface electrode is attached to the area corresponding to T9-T10 of the thoracic vertebrae on the skin of the back and only the back is stimulated, it is found that the effect (activation of swallowing movement) is equal to or greater than that when only the neck is stimulated.

[0052] As described above, it was found that the electrical stimulation device 10 of this embodiment can increase the amplitude (myogenic potential change rate) of the myoelectric potential of the swallowing-related muscles by electrically stimulating at least a predetermined position on the back (a region corresponding to T9 to T10 of the thoracic vertebrae). This suggests that by electrically stimulating at least a predetermined position on the back, the sensory nerves that are present in the stimulation area and reach the swallowing reflex circuit are stimulated, promoting signal transmission of the sensory nerves, which in turn activates the swallowing pattern generator present in the medulla oblongata and activates the entire swallowing reflex circuit.

[0053] [Example of application to the human body (healthy individuals)] Next, a configuration example of the electrical stimulation device 10 of the present embodiment when applied to the human body will be described. Fig. 7 is a diagram showing possible attachment modes of each surface electrode when the electrical stimulation device 10 of the present embodiment is applied to the human body to activate the swallowing function.

[0054] In this example, as shown in FIG. 7, the surface electrodes 3a and 3b constituting the first stimulating electrode unit 3 and the surface electrodes 4a and 4b constituting the second stimulating electrode unit 4 are attached to predetermined positions on the skin of the back of the human body, specifically, to an area corresponding to T9-T10 of the thoracic vertebrae (hatched area in the figure). At this time, the surface electrodes 3a and 3b are attached to a position on the T9 side of the T9-T10 thoracic vertebrae so as to sandwich the T9-T10 thoracic vertebrae, and the surface electrodes 4a and 4b are attached to a position on the T10 side so as to sandwich the T9-T10 thoracic vertebrae. When actually attaching each surface electrode in this manner, each surface electrode is attached by visual inspection and palpation, for example, at about 3 / 4 of the position on a line connecting the base of the neck to the base of the lowest rib when viewed from behind. In this example, a configuration example is shown in which both the first stimulating electrode unit 3 and the second stimulating electrode unit 4 are attached near T9 to T10 of the thoracic vertebrae, but the present invention is not limited to this, and one of the first stimulating electrode unit 3 and the second stimulating electrode unit 4 may be attached near T9 to T10 of the thoracic vertebrae.

[0055] 7, after attaching the surface electrodes of the first stimulation electrode unit 3 and the second stimulation electrode unit 4 to the back of the human body, the electrical stimulation conditions such as various waveform parameters of the electrical stimulation signal 31 are appropriately set. Specifically, the average occurrence frequency f0 of the burst stimulation in the electrical stimulation signal 31, the burst oscillation period tp, and one cycle period tc (specific frequency fc) of the biphasic pulse voltage signal 30a are set.

[0056] As for the absolute value V of the amplitude of the biphasic pulse voltage signal 30a, the output voltage value of the DC / DC converter 13 is gradually increased from a low value to a value that does not cause discomfort or pain while monitoring the current value. At this time, the absolute value V of the amplitude of the biphasic pulse voltage signal 30a is set so that the monitored current value is a current value smaller than the general current value (20 mA) required for direct stimulation of muscles. Then, electrical stimulation is started. During electrical stimulation, the output voltage value of the DC / DC converter 13 is appropriately controlled so that the electrical output is 200 V or less and 20 mA or less in accordance with the JIS (Japanese Industrial Standards) standard for home electrical treatment devices, taking safety into consideration.

[0057] Furthermore, when the electrical stimulation device 10 is applied to the human body, meals may be eaten after electrical stimulation; however, in this example, electrical stimulation is performed by attaching the surface electrodes to the back of the human body, and the electrical stimulation is performed at a low current value, so that the swallowing-related muscles are not directly stimulated and do not contract, and meals can be eaten during electrical stimulation.

[0058] [Various modifications and application examples] The above-mentioned embodiment has been described in detail and specifically with respect to the configuration of the device in order to easily explain the present invention, and is not necessarily limited to the configuration having all of the described configurations. Furthermore, the present invention may take on various other modified and applied examples without departing from the gist of the present invention described in the claims. For example, the following modified and applied examples are conceivable.

[0059] In the above embodiment, a configuration example was described in which the burst stop period tn in the electrical stimulation signal 31 is the reciprocal of the frequency fn randomly selected according to the probability defined by the Gaussian probability distribution with the average occurrence frequency f0 of the burst stimulation as the median, but the present invention is not limited to this. In this method of determining the burst stop period tn, although it is very rare, it is possible that the burst stop period tn becomes extremely short or extremely long. Therefore, in order to avoid these cases (situations), an upper limit and / or a lower limit of the randomly selected frequency fn may be set, and if the selected frequency fn is lower than the lower limit, the frequency fn may be set to the lower limit, and if the selected frequency fn is higher than the upper limit, the frequency fn may be set to the upper limit.

[0060] In the above embodiment, the burst oscillation period tp in the electrical stimulation signal 31 is constant, but the present invention is not limited to this. For example, the burst oscillation period tp may be configured to change with time after the start of stimulation. In this case, the effect of preventing habituation to the stimulation can be further improved.

[0061] In the above embodiment, the signal waveforms of the biphasic pulse voltage signals (biphasic pulse voltage signals 30a, 40a in FIG. 1) applied to each stimulation electrode section are all the same, but the present invention is not limited to this. For example, the signal waveform of the biphasic pulse voltage signal 30a applied between the surface electrode 3a and the surface electrode 3b may be different from that of the biphasic pulse voltage signal 40a applied between the surface electrode 4a and the surface electrode 4b.

[0062] For example, the stimulation voltage value (±V) of the biphasic pulse voltage signal 30a may be made different from that of the biphasic pulse voltage signal 40a. In this case, for example, two DC / DC converters 13 connected to the mobile battery 14 are provided, or two sets of the mobile battery 14 and the DC / DC converter 13 are provided, and the biphasic pulse voltage signal 30a is generated using a DC voltage converted by one DC / DC converter 13, and the biphasic pulse voltage signal 30a is generated using a DC voltage converted by the other DC / DC converter 13. Also, for example, the frequency of the biphasic pulse voltage signal 30a may be made different from that of the biphasic pulse voltage signal 40a. In this case, for example, the control signal input from the microcomputer 11 to the biphasic signal generator 12 may include information on the frequency for the biphasic pulse voltage signal 30a and information on the frequency for the biphasic pulse voltage signal 40a, and the biphasic signal generator 12 may generate the biphasic pulse voltage signal 30a and the biphasic pulse voltage signal 40a based on the frequency information. Furthermore, for example, both the stimulation voltage value and frequency of the biphasic pulse voltage signal 30a may be made different from those of the biphasic pulse voltage signal 40a. In such a configuration, for example, detailed responses are possible depending on conditions such as the stimulation target (movement of the activation target), the stimulation location, and the user.

[0063] In the above embodiment of the electrical stimulation device 10, a configuration example in which two stimulation electrode units (the first stimulation electrode unit 3 and the second stimulation electrode unit 4) each consisting of a pair of surface electrodes are provided has been described, but the present invention is not limited to this. The number of stimulation electrode units each consisting of a pair of surface electrodes is arbitrary, and may be one, or may be three or more.

[0064] In the above embodiment of the electrical stimulation device 10, the biphasic pulse voltage signals 30a, 40a are described as having the same stimulation voltage value and application period applied in the positive direction as the same stimulation voltage value and application period applied in the negative direction, but the present invention is not limited thereto. For example, the stimulation voltage value in the positive direction may be different from the stimulation voltage value in the negative direction, or the application period of the stimulation voltage value in the positive direction may be different from the application period of the stimulation voltage value in the negative direction. In addition, for example, in the biphasic pulse voltage signals 30a, 40a, both the stimulation voltage value in the positive direction and its application period may be different from the stimulation voltage value in the negative direction and its application period. However, for example, when considering the bias of charged ions in the tissue of the skin during electrical stimulation and the ease of generating the biphasic pulse voltage signal, it is advantageous that the stimulation voltage value in the positive direction and its application period are the same as the stimulation voltage value in the negative direction and its application period, as in the biphasic pulse voltage signals 30a, 40a of this embodiment.

[0065] In the above embodiment, in order to activate the swallowing movement, an example was described in which a surface electrode was attached to the area corresponding to T9-T10 of the thoracic vertebrae on the back of a living body to perform electrical stimulation, but the present invention is not limited to this. The surface electrode can be attached at any position, for example, as long as it is a position where a sensory nerve leading to a swallowing reflex circuit exists and where signal transmission of the sensory nerve is promoted when stimulated.

[0066] In the above embodiment, the electrical stimulation device 10 is applied to activate the swallowing movement, but the present invention is not limited thereto. For example, the electrical stimulation device 10 can be used for analgesic treatment or to activate other movements (for example, movements of walking, breathing, anus, rectum, bladder, etc.). In this case, a pair of surface electrodes (surface electrodes 3a, 3b and / or surface electrodes 4a, 4b in the above embodiment) are attached to the skin in an area where a sensory nerve capable of transmitting a sensory signal to a control unit of the brain that transmits a motor command to a muscle related to the other movement to be activated is present, and the electrical stimulation signal 31 is applied in the same manner as in the above embodiment. In this case, various waveform parameters of the applied electrical stimulation signal 31 are appropriately set according to the movement to be activated.

[0067] Furthermore, in the electrical stimulation device 10 of this embodiment, an example has been described in which a sensory nerve capable of transmitting a sensory signal to a control part that transmits a motor command to a muscle involved in a predetermined movement to be activated is stimulated to activate the predetermined movement, but the present invention is not limited to this. The method of electrical stimulation using the electrical stimulation signal 31 (FIG. 2) performed by the electrical stimulation device 10 of this embodiment can also be applied to, for example, an electrical stimulation device that directly stimulates the muscle involved in the predetermined movement to be activated. In this case, the same effect as in this embodiment can be expected.

[0068] [Various effects] As described above, in the electrical stimulation device 10 of the present embodiment, for example, a surface electrode is attached to the back of a living body to perform electrical stimulation, thereby activating the swallowing movement. That is, in the present embodiment, the sensory nerves involved in the movement of the target to be activated are stimulated, thereby indirectly activating the movement. In addition, in the electrical stimulation device 10 of the present embodiment, the burst stop period tn following each burst oscillation period tp (electrical stimulation period) can be randomly changed in the electrical stimulation signal 31 used in the electrical stimulation, and habituation to the stimulation can be suppressed. Therefore, in the electrical stimulation device 10 of the present embodiment, habituation to the electrical stimulation can be prevented, and the motor function of the target to be activated can be better promoted and improved.

[0069] In addition, when the electrical stimulation device 10 of the present embodiment is used to promote swallowing, electrical stimulation can be performed at a low current value, so that the swallowing-related muscles are not directly stimulated during swallowing, causing muscle contraction and preventing natural swallowing. Furthermore, the electrical stimulation device 10 of the present embodiment can perform electrical stimulation at a low current value compared to conventional electrical stimulation devices for promoting swallowing that directly stimulate swallowing-related muscles, thereby reducing discomfort during use.

[0070] In addition, since the skin tissue can be regarded as a parallel circuit of a resistor and a capacitor, in the case of direct current or low frequency electrical stimulation, the skin impedance remains high, the stimulation current flows through the skin surface layer, and the electrical stimulation is not transmitted to the deeper part of the skin. In contrast, in the electrical stimulation signal 31 used in the electrical stimulation device 10 of this embodiment, the specific frequency fc of the biphasic pulse voltage signal 30a generated during the burst oscillation period tp is higher than the average occurrence frequency f0 of the burst stimulation in the electrical stimulation signal 31. That is, the electrical stimulation signal 31 is a signal containing the high frequency component of the biphasic pulse voltage signal 30a and the low frequency component corresponding to the occurrence frequency of the electrical stimulation period. Therefore, in this embodiment, the high frequency component contained in the electrical stimulation signal 31 can reduce the skin impedance, while the low frequency component contained in the electrical stimulation signal 31 can effectively stimulate the deep part of the skin.

[0071] In addition, as a method for effectively stimulating the deep part of the skin, for example, a method of increasing the stimulation voltage, widening the pulse width of the stimulation voltage, increasing the stimulation frequency, etc. can be considered. However, with these methods, for example, if the stimulation voltage is too strong, burns may occur, if the pulse width is too wide, discomfort increases, and if the stimulation frequency is increased, the effect weakens due to habituation to the stimulation. In contrast, as described above, the electrical stimulation device 10 of the present embodiment can perform electrical stimulation with a low current, and can effectively perform electrical stimulation without widening the pulse width or increasing the stimulation frequency, and these various problems can be solved.

[0072] In addition, a technique for performing electrical stimulation using a monophasic pulse wave has been proposed in the past, but in this case, since the current flows in one direction during electrical stimulation, various problems may occur, such as, for example, a bias in the charge ions in the skin tissue, causing inflammation of the skin and damage to the tissue. In contrast, in the electrical stimulation device 10 of this embodiment, as described above, the stimulation voltage signal used during the electrical stimulation period (burst oscillation period tp) is a biphasic pulse voltage signal 30a, and since the current flows in both directions during electrical stimulation, these various problems can be solved.

[0073] In addition, a technique has been proposed in the past that uses a biphasic sine wave voltage signal in which the stimulation waveform is a sine wave rather than a square wave as the electrical stimulation signal, but this technique uses a sine wave, so the effective value of the stimulation voltage is low, and when trying to obtain a stimulation equivalent to that of a square wave, a problem may occur in that a very large current flows through the body instantaneously. However, in the electrical stimulation device 10 of this embodiment, as described above, the waveform of the stimulation voltage signal is a square wave (pulse wave), so the above problem can be solved.

[0074] Furthermore, as a conventional swallowing treatment method other than electrical stimulation, for example, repetitive transcranial magnetic stimulation therapy has been proposed, which directly stimulates the area around the primary somatosensory cortex from the head using magnetic stimulation, but this method has various problems, such as the rehabilitation device being expensive, the introduction cost being high, and the number of institutions where treatment can be received being limited, because the magnetic stimulation device is large. In contrast, the electrical stimulation device 10 of the present embodiment has a simple configuration as described above and can be made into a portable device, so these various problems can be solved. [Explanation of symbols]

[0075] 1...electrical stimulation device main body, 2...surface electrode section, 3...first stimulation electrode section, 3a, 3b...surface electrodes, 4...second stimulation electrode section, 4a, 4b...surface electrodes, 10...electrical stimulation device, 11...microcomputer, 12...biphasic signal generator, 13...DC / DC converter, 14...mobile battery, 15...operation section, 16...display section, 30a, 40a...biphasic pulse voltage signal, 30b, 40b...stimulation current, 31...electrical stimulation signal, f0...average occurrence frequency of burst stimulation, tp...burst oscillation period, tn...burst stop period

Claims

1. A stimulation electrode unit that is attached to the skin of a living body and includes one or more pairs of electrodes to which a stimulation voltage is applied; A stimulation voltage application unit that outputs a stimulation voltage signal to the stimulation electrode unit, The signal waveform of the stimulation voltage signal is a waveform in which a stimulation period during which the stimulation voltage is applied to the living body and a stop period during which the stimulation voltage is not applied to the living body are alternately and repeatedly generated, the signal waveform during the stimulation period is a rectangular wave that periodically switches the application direction of the stimulation voltage between two directions; The stop period is determined each time the stop period occurs based on a frequency that is randomly selected with a probability according to a Gaussian probability distribution with a predetermined frequency as a median. An electrical stimulation device characterized by:

2. The particular frequency of the signal during the stimulation period is higher than the predetermined frequency.

2. The electrical stimulation device according to claim 1 .

3. The pause period is the inverse of the randomly selected frequency.

3. The electrical stimulation device according to claim 1 or 2.

4. The stimulation voltage stimulates a sensory nerve capable of transmitting a sensory signal to a control section of the brain that transmits a motor command to a muscle involved in the movement to be activated.

4. The electrical stimulation device according to claim 1, wherein the electrical stimulation device is a

5. The movement to be activated is a swallowing movement, The attachment position of at least one of the pair of electrodes included in the stimulation electrode unit is a position corresponding to the vicinity of T9 and T10 of the thoracic vertebrae on the back of the living body.

5. The electrical stimulation device according to claim 4.

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