RU2255773C2 - Method and device for carrying out transcranial electric stimulation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: device has the first dipolar pulse oscillator of the first given frequency, modulating control signal source and means for controlling amplitude. The modulating control signal source produces signal of the second frequency that is less than the first given frequency. The signal of the second frequency is used for modulating output pulses of the first oscillator in a way that their amplitude varies with modulating control signal frequency in conformance to given asymmetric shape. Signals of given asymmetric shape are applied to output electrodes fixable on patient head.

EFFECT: small electric current intensity; reduced risk of burns and pain feeling.

17 cl, 3 dwg

Description

BACKGROUND OF THE INVENTION

It is known to use bioelectric stimulation devices for supplying current pulses to a patient through electrodes mounted on opposite sides of the patient's head. Pulses of current with a given frequency are applied in order to cause a reaction of the central nervous system of the patient. Such devices, known as transcranial electrostimulation devices (TCES) or cranial electrostimulation devices (CES), are used in various non-invasive procedures, such as obtaining analgesic effects, reducing or preventing headaches such as migraines, as well as in other types of treatment and electric analgesics.

The earliest prototypes of transcranial electrostimulation devices appeared in Russia. These original developments, although they are successfully used in various types of treatment, have serious drawbacks in terms of user or patient comfort. In some cases, these early cranial electrical stimulation devices even hurt the user. It was found that the cause of the discomfort created by these early devices was the use of direct current during the operation of such devices. Direct current in such devices is used to reduce the resistance of the skin, in order to allow AC signals to penetrate the brain and nervous system and cause the desired effect obtained by installing electrodes on the patient’s head.

In these early devices, the user receives a combination of packages of electrical oscillations of direct current and alternating current using a series of electrodes mounted on the head with straps. Typically, two electrodes forming a cathode or negative pole of a direct current (DC) circuit are placed at a distance of about three inches to the left and right of the center of the forehead. The other two electrodes forming the anode or positive pole of the DC circuit are placed at the back of the skull in the posterior mandibular region, behind and below each ear. In this DC-based design, a thick lining (pillow) is applied between each electrode and the skin of the user. Typically, such a lining contains several layers of unbleached and unpainted cotton flannel or other similar fabric. For best results, fabric pads are wetted with water to form a current path between the electrodes and the skin of the user. Without linings (which are necessary only due to the presence of direct current), such an apparatus either causes a skin burn or creates relatively severe pain before a useful healing level of currents with an alternating current frequency is achieved.

Despite the fact that various types of treatment were successfully carried out using these early devices for transcranial electrostimulation, we note that treatment is usually carried out for about 30 minutes, and without the use of bulky and relatively thick pads, devices using direct current are unsuitable. When using thick gaskets, the user can still carry the DC application, but still gets an unpleasant feeling.

Among the patents of Russia protecting such devices used for various types of treatment, patents 1489719 can be mentioned; 1507404 and 1522500. In all these patents, it is proposed to use a combination of direct current and rectangular current pulses, with a frequency between 70 and 80 Hz, and during the treatment session, the current strength is increased from a relatively low level to a higher or maximum level.

An additional and potentially dangerous drawback of DC devices is iontophoresis. In applications of this type using direct current, the migration of molecular-sized metal particles, toxins, and other undesirable impurities can occur in the direction of the current flowing through the skin and further into the user's circulatory system by such a DC-based CES apparatus. Therefore, care must be taken to ensure that no substances other than water are used on the pads, which is used to create good electrical contact between the pads and the patient’s skin. Since almost all types of CES treatment require several sessions, the potential for the harmful effects of iontophoresis increases.

Transcranial electrical stimulation (CES or TCES) in the 60s was originally used to induce sleep. In such early devices, a current of less than 1.5 mA with a frequency of 100 Hz was usually used. U.S. Pat. 4627438 used higher frequencies modulated by square waves of a lower frequency to obtain periodic bursts of pulses. The repetition rate in the device described in said patent is determined by the modulation frequency; however, the pulse packets have a constant amplitude during each repetition cycle. The specified device is specifically intended for use in the treatment of headaches such as migraines. The low frequency signal or modulating signal is asymmetric, with a 3: 1 duty cycle with a turn-on time of 3/4 of the repetition period and a turn-off time of 1/4 of the repetition period. This results in packets of high frequency signals separated by a gap of no signal, after which packets of high frequency signals again appear. In such systems with “on and off” signal, some patients may experience discomfort during the period of application of the impulse in the treatment interval.

Several other U.S. patents are also known in which two-frequency systems are described in which high frequency signals are modulated using low frequency carrier modulation, the basic principle of operation of such devices being in accordance with said U.S. Pat. No. 4,627,438. U.S. Pat. 3,835,833; No. 4,071,033; No. 4,140,133; No. 4922908 and No. 5131389. All of these patents use a high-frequency signal with a constant (constant) amplitude, which is modulated by low-frequency carrier modulation.

One embodiment of the systems described above is disclosed in US Pat. 5540736. In the device of this patent, two different current generators are used to create electric currents that are applied to two pairs of electrodes superimposed on different parts of the patient’s head. This allows independent control of current generators and the creation of independently regulated electric currents in each of the pairs of electrodes in order to take into account various impedances caused by physiological and anatomical differences between different sides of the middle part of the patient’s brain, the quality of the conducting medium and other factors. In all other respects, the system described in this patent works similarly to the system described in US Pat. 4627438, which was discussed above.

In the patent of Russia No. 2139111 describes a method for the treatment of drug addiction, moreover, this method of treatment is already used in the other CES patents described above, and the difference lies in its use for the treatment of alcohol and drug addiction. This patent describes the implementation of transcranial electrical stimulation using current packets with a duration of 4 ms, with a modulation frequency of 100 Hz. Inside each packet, high-frequency signals have a constant frequency and amplitude of the current.

It is desirable to create a device and method for transcranial electrical stimulation, which will eliminate the disadvantages of previously known solutions, as well as increase the efficiency of their use and improve user comfort.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide an improved device for transcranial electrostimulation and a method for its implementation.

An additional objective of the present invention is to provide an improved device for transcranial electrostimulation and a method for its implementation, which do not use components that operate on direct current.

Another objective of the present invention is to provide an improved device for transcranial electrostimulation and a method for its implementation, in which only components operating on alternating current are used.

Another objective of the present invention is to provide an improved device for transcranial electrostimulation and a method for its implementation, in which they use packets or groups of high-frequency pulses with a change in amplitude in each of the packets in a uniform way, and the packets are repeated with a lower modulation frequency and fed to the electrodes for implementation transcranial electrical stimulation.

In accordance with a preferred embodiment of the present invention, a device for transcranial electrostimulation includes a first bipolar pulse generator with a first predetermined frequency. A source of modulating control signals is used with a second frequency that is less than the first predetermined frequency, together with an amplitude control circuit receiving pulses of a first predetermined frequency, in order to obtain bipolar pulses with a first predetermined frequency, which vary in amplitude asymmetrically with the frequency of the modulating control signals.

Brief Description of the Drawings

Figure 1 schematically shows the General principles of the system in accordance with a preferred embodiment of the present invention.

Figure 2 shows a typical waveform in accordance with a preferred embodiment of the present invention.

Figure 3 shows a block diagram of a system for receiving the signals shown in figure 2.

DETAILED DESCRIPTION OF THE INVENTION

We now turn to the consideration of the drawings, which show a preferred embodiment of the present invention and its operation is explained. Figure 1 schematically shows the most important elements of the circuit, which allows you to create a unique triple asymmetry of vibrations, useful for various applications of transcranial electrical stimulation. Note that the unique waveform, described in detail with reference to figure 2, creates slight discomfort for the user or does not create it at all.

As shown in FIG. 1, the main high-frequency current signals are generated using a high-frequency generator 10, in which a frequency control circuit 12 and a pulse width control circuit 14 are used to obtain the fundamental frequency and the desired asymmetry between the positive and negative parts of each pulse, obtained using the generator 10. Typically, the generator 10 is a crystal oscillator operating at a frequency of from 1,000 to 1,200 kHz, which is then divided to obtain the desired operating frequency of the variable imp current pulses applied to electrodes of transcranial stimulation. Typically, the division ratio can be 1: 4, which allows you to receive signals, which are then modulated using a low frequency generator 16.

As shown schematically in FIG. 1, the low frequency generator 16 is provided with a frequency control circuit 18, a pulse width control circuit 20, and a modulation depth control circuit 22, which makes it possible to obtain a composite modulated output signal at output 24, which contains pulses from the output of the high frequency generator 10, modulated by a low-frequency generator 16. The output stage 24 is equipped with an amplitude control circuit 26, which allows you to adjust the amplitude of the sequence of pulses supplied to the power amplifier 28. Issue STI using the power amplifier 28 current, which is measured with an ammeter 34 may vary depending on the type of treatment. The power amplifier 28 supplies the corresponding transcranial alternating current pulses to a pair or to a plurality of pairs of electrodes, which are shown in Fig. 1 as a single pair 30 and 32.

Next, the operation of the preferred embodiment of the device in accordance with the present invention, which allows to obtain an oscillating signal having triple asymmetry and providing effective transcranial electrical stimulation, will be considered with reference to the waveform of Fig.2 and the block diagram of the system shown in Fig.3. Note that the block diagram of the system shown in FIG. 3 is typical and includes various schemes necessary to obtain the waveform of FIG. 2; however, other constructions can be used to obtain such a waveform.

The crystal oscillator 50 shown in FIG. 3 is used to generate basic AC operating signals that are used both in the high frequency pulses and in the modulating pulses of FIG. 1 obtained by the high frequency generator 10 and the low frequency generator 16. Typically, the generator 50 It is a source of biopolar pulses of the first given frequency and can have an operating frequency of approximately 1,000 kHz to 1,200 kHz (although other frequencies can be used). The signal from the output of the generator 50 is fed to a divider 52, which can have many stages of division and allows you to get modulating control signals with a lower modulating frequency (which is obtained in figure 1 with a low frequency generator 16), thus, the source of modulating control signals is divider 52. The signal from the output of the generator 50 also goes to the divider 54, which allows you to get the working waveform (bipolar pulses of the first predetermined frequency), shown as a square wave on f ig. 2, after forming in the pulse shaper 56, which provides mainly a rectangular waveform of FIG. 2. In this example, these pulses have an AC frequency of 100 kHz; however, in accordance with particular embodiments of the present invention, pulses may have higher or lower frequencies.

Pulses from the output of the divider 54 are also supplied to the counter 60, which can be used as a suitable counter of any type, such as a cascade counter or a ring counter, which allows you to receive output signals at pins 64 and 66, which are used to control the amplitude of the pulses from the pulse shaper 56 The counter 60 is reset to its initial position according to the signal from the output of the divider 52 received via line 62, and the reset is made in each period of operation of the divider 52. In this example, the output signal of the divider 52 (which is presented This is a control signal of low modulation frequency) has a frequency of 77.5 Hz, since it was found that such a repetition rate is most effective for use in transcranial electrostimulation devices. It was found that repetition frequencies in the range of 70 Hz to 85 Hz are effective, but it has been empirically determined that the frequency of 77.5 Hz is an ideal operating frequency that ensures maximum system efficiency.

The modulation frequency or the reset (zeroing) frequency supplied via line 62 can also be created, if desired, with a second independent crystal oscillator operating at a lower initial frequency than generator 50. If two different signal sources are used, they must be synchronized. so that the different fronts of the pulses correlate with each other and allow to obtain the waveform of figure 2. However, the system shown in FIG. 3 allows this to be achieved in the most efficient manner.

Suppose that the counter 60 is reset to its original or zero position. High frequency pulses are divided using a divider 54 and fed to the input of the counter, the readings of which increase by one with each incoming pulse. In the waveform shown in FIG. 2, the initial pulses (the first four on the left in FIG. 2) have a maximum amplitude (which can be controlled as desired) provided by amplitude control circuit 68. When passing pulse No. 4 of the group or packet, the signal 64 and / or 66 from the counter 60 passes through the amplitude control circuit 68, which switches to the lower amplitude shown in the right part in figure 2.

The output signal from the amplitude control circuit 68 is supplied to an amplifier-stabilizer 58, which creates the asymmetric waveform shown in FIG. 2, in which the left quarter (42) of each signal packet has a higher amplitude, and the right section (44) contains the remaining pulses with lower amplitude. The ratio is chosen in such a way that one quarter (the initial amplitude) of the pulses lies in the range of high amplitudes, and the remaining three quarters of the pulses lie in the range of low amplitudes. This forms the first level of asymmetry of the applied signals.

The amplitude control means 68 defines bipolar pulses having a large amplitude in the first part of each group of pulses and a smaller amplitude in the second part of each group of pulses, and the amplitude of the pulses in the first part of each group of pulses is mainly three times the amplitude of the pulses in the second part.

The amplifier-stabilizer 58 also works with rectangular pulses from the pulse shaper 56 and creates a second asymmetry in the positive and negative regions of the signal. As shown in FIG. 2, the amplitude of the negative region is 1/4 of the full scale of the signal, and the amplitude of the positive region is 3/4 of the full scale of the signal. This is true both for section 42 of the maximum pulse amplitude at the beginning of each burst or pulse train, and for section 44 of lower pulse amplitude at the end of each burst or pulse train.

Finally, a third asymmetry is created in the envelope of a burst of rectangular pulses with a duration of 13 ms, indicated by 40 in FIG. 2. This is the result of resetting the counter 60 by a signal from the divider, which is received on line 62.

The composite asymmetric signal shown in FIG. 2, received at the output of the stabilizer-amplifier 58, is supplied to a power amplifier 70, the gain of which can be adjusted to change the current flowing into the system (but while maintaining the shape and ratios of the parts of the vibrational signal shown in FIG. 2), in accordance with the requirements for treatment using the system prescribed to patients. To measure the current flowing into the system, an ammeter 74 is used. This can be a simple analog ammeter or a digital ammeter, which allows you to separately measure sections of the maximum amplitude and minimum amplitude of the signal, which are shown in figure 2.

The signal from the output of amplifier 70 can pass through a polarity switch 72, which allows you to optionally reverse the polarity of the signals applied to the electrodes installed spaced apart from each other. The signal from the output of the polarity switch 72 is fed to a pair of output electrodes 76 and 78 installed spaced apart from each other, which may be in the form of a pair of split anodes and split cathodes or in the form of a pair formed by a single anode and a single cathode. So, the output electrodes 76 and 78 are connected to the amplitude control means 68 through an amplifier-stabilizer 58, an amplifier 70, and a polarity switch 72. Since there are absolutely no DC components in the signal, the pair of output electrodes 76 and 78 is not really a pair of anodes and cathodes, and, depending on the type of treatment, it may be desirable to apply positive sections of pulses to one of these electrodes, and negative sections of pulses to another of them, in order to obtain specific p treatment results.

It should be borne in mind that in the system described with reference to the drawings, there are absolutely no DC components. It should also be borne in mind that despite the fact that in the signal of the system shown in FIG. 2, tonal signals from 70 kHz to 120 kHz are used in each envelope of the pulse train 40, other frequencies can be successfully used for this. As already mentioned here, the 77.5 Hz vibrational signal obtained during the synchronization period is used to complete each envelope of the pulse train, which includes the first pulses of relatively high amplitude, followed by a series of pulses of relatively low amplitude, as shown in the sequence pulses in figure 2.

The proposed system uses individual rectangular pulses with a duration of 0.01 ms, with a negative section of each pulse of 0.0075 ms and a positive section of each pulse of 0.0025 ms. It was found that the asymmetric oscillatory signal described here earlier with reference to figure 2, is effective in the case when during the operation of the system maintains a 3: 1 ratio of negative and positive sections. The asymmetry of the amplitude of the first and second sections of the tone transmission is mainly 1: 3 and the duration of the positive and negative sections of each pulse of the tone transmission also has a ratio of 1: 3. It goes without saying that this ratio may vary depending on changes in other characteristics of the system; however, it was found that the specified asymmetric ratio allows you to replace the DC section, which was necessary in previously known systems, but which creates unpleasant sensations in the patient.

Note that direct current was used in some previously known systems in order to create a path through the natural capacitive resistance of human skin, and direct current reduces this resistance to approximately 300 to 400 Ohms. However, this is achieved due to the high level of user discomfort. It was found that using the unique asymmetric signal shown in FIG. 2 and obtained using the system shown in FIG. 3 can effectively reduce the capacitance of the epidermal layer to a value of the order of 100 Ohms. Since the proposed system provides a lower resistance at a modulation frequency of 77.5 Hz, lower current strengths allow you to get the same desired result, which previously required much higher current strengths, and using a lower current strength leads to a greater level of patient comfort.

Despite the fact that the preferred embodiment of the invention has been described, it is given only as an example to explain the invention and is not restrictive, and it is clear that experts and experts in this field may make changes and additions that do not apply, however, beyond the scope of the following claims.

Claims (17)

1. A method of transcranial electrical stimulation, which includes the following operations: creating an asymmetric envelope of a tonal package containing a given number of rectangular pulses, the first section of which is formed by a packet of high-amplitude pulses, followed by a second section, formed by a packet of low-amplitude pulses; sequential repetition of an asymmetric tonal pattern with a repetition rate of 70 to 85 Hz and the supply of repeating tonal pattern signals to the electrodes of a transcranial electrical stimulation device. 2. The method according to claim 1, characterized in that the frequency of the pulses forming an asymmetric tonal pattern exceeds the repetition rate by approximately 1150-1450 times. 3. The method according to claim 1, characterized in that the duration of the first high-amplitude section of each tone transmission is mainly 25% of the total duration of the tone transmission. 4. The method according to claim 1, characterized in that the operation of creating an asymmetric envelope of the tone package includes creating a tone package that is asymmetric in amplitude and asymmetric in the relative duration of the positive and negative sections of each full cycle of the tone signal. 5. The method according to claim 4, characterized in that the ratio of the asymmetry of the amplitudes of the first and second sections of the tone parcel is mainly 1: 3, and the durations of the positive and negative sections of each pulse of the tone parcel also have a ratio of 1: 3. 6. The method according to claim 5, characterized in that the frequency of the pulses forming an asymmetric tonal package exceeds the repetition rate by approximately 1150-1450 times. 7. The method according to claim 6, characterized in that the duration of the first high-amplitude section of each tone transmission is mainly 25% of the total duration of the tone transmission. 8. Device for transcranial electrical stimulation, characterized in that it includes a source of bipolar pulses of the first predetermined frequency; a source of modulating control signals, allowing to obtain a second frequency that is less than the specified first predetermined frequency; amplitude control means using modulating control signals connected to a bipolar pulse source with a first predetermined frequency and causing a change in the amplitude of bipolar pulses in successive groups of bipolar pulses with a second frequency in accordance with a given asymmetric shape, and output electrodes. 9. The device for transcranial electrical stimulation according to claim 8, characterized in that the pulse shaper is connected to a source of bipolar pulses of a first predetermined frequency to form a time delay of bipolar pulses of a first predetermined frequency. 10. The device for transcranial electrostimulation according to claim 9, characterized in that the amplitude control means is configured to specify bipolar pulses of greater amplitude in the first part of each group of pulses and of smaller amplitude in the second part of each group of pulses. 11. The device for transcranial electrical stimulation according to claim 10, characterized in that the amplitude of the pulses in the first part of each group of pulses is mainly three times the amplitude of the pulses in the second part. 12. The device for transcranial electrical stimulation according to claim 11, characterized in that the output electrodes are connected to the amplitude control means. 13. The device for transcranial electrical stimulation according to claim 11, characterized in that the source of modulating control signals is a frequency divider connected to a source of bipolar pulses of the first predetermined frequency. 14. The device for transcranial electrostimulation according to claim 8, characterized in that the amplitude control means is configured to specify bipolar pulses of greater amplitude in the first part of each group of pulses and of smaller amplitude in the second part of each group of pulses. 15. The device for transcranial electrical stimulation according to 14, characterized in that the amplitude of the pulses in the first part of each group of pulses is mainly three times the amplitude of the pulses in the second part. 16. The device for transcranial electrical stimulation according to claim 8, characterized in that the output electrodes are connected to the amplitude control means. 17. The device for transcranial electrical stimulation according to claim 8, characterized in that the source of modulating control signals is a frequency divider connected to a source of bipolar pulses of the first predetermined frequency.

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