JP2021053247A - Vestibular electrical stimulation device - Google Patents

Abstract

To provide a vestibular electrical stimulation device for percutaneously giving noise electrical stimulation in which adherence failure with an electrode and the skin or interruption of the electrical stimulation by the drying of the skin surface can be avoided in advance.SOLUTION: A vestibular electrical stimulation device 1 includes: a determination unit 111 for determining an output level of noise electrical stimulation being output from electrodes 11, 12; and a display unit 112 for displaying the determined output level step by step. The determination unit 111 measures an output voltage Vout of the electrode 11 for a predetermined period, and determines an output level on the basis of the maximum value VoutMax of the measured output voltage. Also, a microcomputer 101 may estimate the maximum output voltage VoutMax from a current command value Ic(t) for commanding an output stage 107, and determine the output level on the basis of the maximum output voltage VoutMax.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vestibular electrical stimulator that improves the body balance function of a patient by applying noise electrical stimulation to the peripheral vestibular system of the patient with vestibular dysfunction, and particularly includes an improved disconnection detection unit. Regarding vestibular electrical stimulator.

The peripheral vestibule is a nervous system organ that detects the rotational acceleration and linear acceleration of the head and is mainly responsible for maintaining fixation and body balance during body movement through the vestibulo-eye reflex and vestibulo-spinal reflex. When the vestibule is impaired, vertigo, light-headedness, and impaired body balance occur. Percutaneous noise electrical stimulation to the peripheral vestibular system is effective in improving the orthostatic circulatory response in patients with autonomic dysfunction, improving motor function in patients with spinocerebellar degeneration, and improving autonomic function in patients with Parkinson's disease. Has been reported.

A portable vestibular electrical stimulator (GVS (Galvanic Vestibular Stimulation)) that allows a patient with vestibular dysfunction to have an electrode always attached to the patient's head so that he or she can lead a normal daily life without any trouble. ) Device) has already been developed (see Patent Document 1). According to this GVS device, a weak noise stimulus can be continuously applied for a long time through a pair of electrodes attached to the back of the patient's ear. It was also confirmed that when noise stimulation is continuously given to a patient with vestibular dysfunction for 3 hours, there is a so-called "carry-over effect" in which the improvement effect of body balance function lasts for at least 2 hours even after the stimulation is completed. (See Non-Patent Document 1).

Design Registration No. 1634706 Gazette

Shinichi Iwasaki, 2017, Improvement of body balance function in patients with bilateral vestibular disorders using noise vestibular electrical stimulation, Equilibrium Res. Vol.76 (3) pp. 195-203

The conventional GVS device is provided with a disconnection detection unit that determines a disconnection error when the output of the electrode terminal swings to the rated value (for example, ± 20 V). However, even if there is no abnormality in the device itself, for example, even if the electrodes are not firmly attached to the skin, or if the electrodes float with sweat during use and the electrical resistance increases. It was determined that the wire was broken, and each time there was an inconvenience that the electrical stimulation was interrupted.

In addition, the skin resistance of a person is about an order of magnitude higher when it is dry than when it is moist, and even in such a case, the output may be determined to be a breakout. However, there is a skin pretreatment agent, and it is recommended to remove the keratin in advance to reduce the resistance before use, but when the treatment is insufficient or it is used without treatment, the disconnection is detected at first. Although it was not used, it was used in an unstable state with high resistance, and there was a problem that it was judged to be broken and interrupted.

The present invention has been made in view of such conventional problems, and in a vestibular electrical stimulator that percutaneously applies noise electrical stimulation, electrical stimulation due to poor adhesion between electrodes and skin, drying of the skin surface, and the like. It is an object of the present invention to provide a vestibular electrical stimulator that can avoid interruption of the skin as much as possible.

In order to solve the above-mentioned problems, the present invention is a vestibular electrical stimulator that applies noise electrical stimulation to the peripheral vestibular system of the patient via a pair of electrodes in close contact with the patient's skin, and is output from the electrodes. This is a vestibular electrical stimulation device including a determination unit for determining the output level of the noise electrical stimulation and a display unit for stepwisely displaying the determined output level.

In the vestibular electrical stimulation device, it is preferable that the determination unit measures the output voltage of the noise electrical stimulation for a predetermined period of time and determines the output level based on the maximum value of the measured output voltage.

In the vestibule electrical stimulator, a current range storage unit that stores the current range set value set for each patient and a current conversion unit that outputs a current according to the current command value that forms the waveform of the noise electrical stimulation from the electrodes. And here, the conversion coefficient K,
Conversion coefficient K = current range set value / current command value shall be defined.
The determination unit calculates the estimated maximum output voltage of the noise electrical stimulation by multiplying the output voltage of the noise electrical stimulation by the conversion coefficient K, and determines the output level based on the maximum output voltage. It may be something to do.

In the vestibular electrical stimulator, the determination unit preferably determines the output level based on the average of the maximum output voltages when the conversion coefficient K is 1 or more and a predetermined value or less.

The vestibular electrical stimulator according to the present invention constantly monitors the output level of the noise electrical stimulus output from the electrodes and displays the output level stepwise. As a result, it is possible to urge the user to reattach the electrodes before the disconnection error is determined, and it is possible to avoid interruption of electrical stimulation due to poor adhesion between the electrodes and the skin in advance.

It is a circuit block diagram of the vestibular electric stimulator according to one Embodiment of this invention. It is a figure which illustrates the source data of the white noise for forming a noise electrical stimulation waveform. It is a flowchart for demonstrating the output level display processing by Example 1. FIG. It is a figure for demonstrating the determination condition of an output level, and the content thereof. It is a figure which illustrates the display screen in the display part. It is a flowchart for demonstrating the output level display process by Example 2. FIG. It is a figure which exemplifies the relationship between the waveform of white noise electrical stimulation, and the conversion coefficient K (t).

Hereinafter, preferred embodiments of the vestibular electrical stimulator according to the present invention will be described in detail with reference to the drawings. The vestibular electrical stimulator (hereinafter referred to as "GVS device") is a device for improving the body balance function of a patient with vestibular dysfunction by percutaneously applying noise electrical stimulation to the peripheral vestibular system of the patient. Is. Even a patient with dizziness or light-headedness can be assisted by wearing a portable GVS device so that he / she can lead a normal daily life.

FIG. 1 is a circuit block diagram of a portable GVS device 1 according to an embodiment of the present invention. The GVS device 1 outputs a noise stimulating current to the electrodes 11 and 12 via an ear-hook type electrode wearing device in which an out-side electrode 11 and a return-side electrode 12 are embedded in a pair of left and right electrode pads, respectively. It is configured to include a controller 10.

Although not shown, the electrode mounting tool has a substantially semicircular arc-shaped elastic frame, an electrode pad in which electrodes 11 and 12 are embedded in both tip portions thereof, and an ear hook portion. By hanging the elastic frame around the back side of the patient's neck and hooking the ear hooks at the tips to the left and right outer ears, the electrodes 11 and 12 can be brought into close contact with the rear parts of the left and right ear lobes. .. By passing a weak white noise current from the back of the earlobe through the electrodes 11 and 12, the peripheral vestibule behind the inner ear can be stimulated and an appropriate reaction can be generated in the nervous system.

The EPROM 102 of the controller 10 stores, for example, a plurality of types of noise electrical stimulation source data having a white noise waveform as shown in FIG. White noise is noise that contains all frequency components equally. Stimulation with white noise, whose amplitude and cycle change randomly over time, has been shown to significantly increase walking speed in multiple patients. For example, the EPROM 102 stores source waveform data that imitates white noise for 200 seconds, and the microcomputer 101 repeatedly reproduces the white noise with 200 seconds as one cycle, so that the electricity of the noise waveform that is continuous for a long time is electric. A stimulus can be formed.

The RAM 103 temporarily stores the set white noise waveform identification information, the current range set value, the continuous operation time (also referred to as the set time), and other setting information. The operating conditions of the GVS device 1, such as the noise waveform, the current range, and the set time, can be input and changed from the setting operation unit 104.

Here, the current range means the current range output from the electrodes 11 and 12 as noise electrical stimulation, and the current range set value (Irange) means the absolute value of the maximum current in the set current range. This current range is determined by testing the optimal stimulation level of the patient in advance according to the age, sex, degree of physical dysfunction, etc. of the patient. It should be noted that it may be appropriately set according to the physical condition of the patient on that day.

The microcomputer 101 reads the waveform data imitating white noise from the EPROM 102, adjusts to the set current range, and outputs the current command value Ic (t) according to the read waveform data to the DA conversion unit 105. Here, the current command value Ic (t) is a digital command value depending on the time t that forms the waveform of the noise electrical stimulation in the set current range, and is a logic level (0 to 5 V) by the DA conversion unit 105. ) Is converted to a voltage value. Further, the current command value is converted from the logic level to a drive level of ± 20 V by the level shift circuit unit 106.

The voltage-current converter 107 is feedback-controlled by an operational amplifier circuit so that a noise stimulating current according to a current command value Ic (t) flows through the patient's body (internal resistance 13) via a pair of electrodes 11 and 12. It is composed. The current flowing from the out-side electrode 11 of the voltage-current conversion unit 107 into the patient's body is recovered by the return-side resistor 12 via the internal resistance 13, and the value is detected by the current detection resistor 108. The voltage value detected by the current detection resistor 108 is fed back to the voltage-current conversion unit 107 (negative input of the operational amplifier) and compared with the current command value of ± 20V which is the output of the level shift circuit unit 106. Voltage-current conversion is performed.

By repeating the above sequence until the timer 113 finishes counting the set time, the microcomputer 101 gives the patient an electrical stimulus imitating white noise continuously for the set time via the electrodes 11 and 12. While the GVS device 1 operates normally, the display unit 112 is displayed with a white noise waveform (for example, “B”) and a current range (for example, “± 150 μA”) together with a set time and an elapsed time, for example, as shown in FIG. ), Operation information such as the output level (for example, "3") described later is displayed. As the display unit 112 for displaying such numerical values and character information, for example, an LED dot matrix display can be used.

The GVS device 1 according to the present embodiment includes a disconnection detection unit that determines when the electrodes 11 and 12 are disconnected or the cable is disconnected. The disconnection detection unit includes a level shift circuit unit 109, an AD conversion unit 110, and a determination unit 111 shown in FIG. The ± 20V range output voltage output from the electrode 11 by the voltage-current conversion unit 107 is stepped down to a logic level voltage value in the 5V range by the level shift circuit unit 109. Then, the output voltage at the logic level is converted into a digital value by the AD conversion unit 110 and input to the microcomputer 101. The determination unit 111 determines that the wire is broken (or the electrodes 11 and 12 are peeled off from the skin) when the output voltage (or the voltage between the electrodes 11 and 12) of the voltage-current conversion unit 107 swings to ± 20V. When the microcomputer 101 detects a disconnection, it executes error processing such as operation stop and error notification.

If the electrodes 11 and 12 are peeling off from the skin, the electrodes 11 and 12 float due to sweat, or if the skin is dry and the skin resistance is high and the use of the GVS device 1 is continued, between the electrodes 11 and 12. The resistance may increase and it may be erroneously determined as a disconnection, and the stimulation may be interrupted frequently. The GVS device 1 according to the present embodiment has an output level display function in order to avoid an undesired interruption due to poor adhesion between the electrodes 11 and 12 and the skin. In the output level display function, the determination unit 111 of the microcomputer 101 determines the output level of noise electrical stimulation at any time by using the above-mentioned disconnection detection unit, and the display unit is displayed in, for example, five stages (may be a number or a bar display). The output level is displayed on 112.
Since the output voltage of the electrodes 11 and 12 is affected by the electrical resistance (impedance) between the electrodes 11 and 12 and the skin, by displaying the output level of the electrical stimulation step by step, the electrodes 11 and 12 are firmly attached to the skin. It is possible to inform the user whether the skin is stuck or peeled off, or the skin resistance is high. By displaying the output level of electrical stimulation in this way, before it is judged as a disconnection error, the electrodes are held down and brought into close contact with each other, care is taken not to pull the cable, or the arrangement of the cable is changed. Alternatively, the user can be urged to reattach the electrodes 11 and 12, and interruption of electrical stimulation due to poor adhesion of the electrodes 11 and 12 can be avoided in advance.

Hereinafter, specific examples of the characteristic output level display function in the present invention will be described with reference to the flowchart. The output level display function is a function realized by the CPU (determination unit 111) of the microcomputer 101 executing arithmetic processing.

(Example 1)
The output level display process according to the first embodiment will be specifically described with reference to FIG. When the process is started, the microcomputer 101 initializes the time counter of the timer 113 and starts the time measurement (step S11). Further, the maximum output voltage VoutMax of the noise electrical stimulation output from the electrode 11 is initialized to 0 (step S12). Here, VoutMax is a variable that stores the value of the maximum output voltage of the noise electrical stimulation.

The determination unit 111 determines whether the absolute value | Vout | of the output voltage Vout of the electrode 11 or the output stage operational amplifier 107 is 19 V or more (step S13). If the output voltage Vout swings to ± 19V or more (step S13: Yes), the microcomputer 101 performs disconnection error processing such as operation stop and error notification (step S14).
The determination unit 111 (disconnection detection unit) may monitor the voltage Vout_d between the pair of electrodes 11 and 12 and determine that a disconnection error occurs when Vout_d swings to ± 19V or more.

If the absolute value | Vout | of the output voltage is smaller than 19V (step S13: No), it is determined that normal operation is in progress, and the determination unit 111 then determines the absolute value of the output voltage | Vout | and the above-mentioned maximum output voltage. Compare with VoutMax (step S15). If | Vout |> VoutMax (step S15: Yes), the maximum output voltage VoutMax is updated to the absolute value | Vout | of the output voltage (step S16).

As in the case of disconnection detection, the voltage Vout_d between the electrodes 11 and 12 may be monitored, and the maximum output voltage VoutMax may be updated according to the maximum value thereof.

The determination unit 111 repeats the above-mentioned disconnection determination process (step S13) and maximum output voltage detection process (steps S15 and S16) until the timer 113 measures, for example, 1 minute, which is a predetermined time (step S17). Then, at the timing when 1 minute has passed from the start (step S17: Yes), the determination unit 111 determines the level of the maximum output voltage VoutMax of the noise electrical stimulation output in that 1 minute (step S18).

For example, as shown in FIG. 4, five levels are determined according to the value of the maximum output voltage VoutMax. The poorer the contact state between the electrodes 11 and 12 and the skin (that is, the electrodes are about to peel off), the higher the impedance of the contact. As the impedance between the electrodes 11 and 12 and the skin increases, the maximum output voltage VoutMax also increases, so that the contact state between the electrodes 11 and 12 and the skin can be indicated depending on the output level.

The microcomputer 101 displays the output level determined by the determination unit 111 on the display unit 112 as a number, for example, as shown in FIG. 5 (step S19). In addition, a message may be displayed depending on the output level. For example, if the level is "5", "The electrodes are peeling off. Please reattach.", And if the level is "4", "The electrodes are peeling off. Please check." A warning or caution statement such as may be added next to the output level number.

According to the GVS device 1 of the present embodiment, the output level of the noise electrical stimulation output from the electrodes 11 and 12 is constantly monitored, and the output level is displayed stepwise on the display unit 112. As a result, it is possible to urge the user to reattach the electrodes 11 and 12 before the disconnection error is determined, and it is possible to avoid interruption of electrical stimulation due to poor adhesion between the electrodes 11 and 12 and the skin in advance. it can.

(Example 2)
As another embodiment, the determination unit 111 may calculate the maximum output voltage VoutMax of the noise electrical stimulation estimated from the above-mentioned current command value Ic (t) and determine the output level.

Here, the conversion coefficient K (t) for calculating the maximum output voltage VoutMax is defined by the following equation (1).

Conversion coefficient K (t) = Current range set value Irange / Current command value Ic (t) ・ ・ ・ Equation (1)

The maximum output voltage VoutMax (t) can be estimated using the following equation (2), that is, by multiplying the output voltage Vout by the conversion coefficient K (t).

Maximum output voltage VoutMax (t) = conversion coefficient K (t) x output voltage Vout ・ ・ ・ Equation (2)

However, in the methods (1) and (2) for estimating the maximum output voltage VoutMax from the current command value Ic (t), the accuracy becomes worse as the current of the command value Ic (t) becomes smaller, and the skin is still. Depending on the capacitance, the noise waveform that is actually output is blunted, which may cause an error in the maximum output voltage VoutMax. Therefore, in order to further improve the accuracy, it is preferable to determine the output level based on the maximum output voltage average VoutMaxMean averaged in a range in which the current value of the noise stimulus is larger than a certain level, as shown in the flowchart of FIG. Therefore, the output level display process according to the second embodiment will be specifically described with reference to FIG.

First, the microcomputer 101 initializes the count variable Count, which is the number of times the output voltage Vout is measured, in order to calculate the average of the output voltage Vout (step S21). Here, for example, 8 is input as the initial value of the count variable Count.
Further, the microcomputer 101 initializes the variable Sum that stores the integrated value of the maximum output voltage to 0 (step S22).

The determination unit 111 determines whether the absolute value | Vout | of the output voltage Vout of the electrode 11 (or the output stage operational amplifier 107) is 19 V or more (step S23). If the output voltage Vout swings to ± 19V or more (step S23: Yes), the microcomputer 101 performs disconnection error processing such as operation stop and error notification (step S24).

If the absolute value | Vout | of the output voltage is smaller than 19V (step S23: No), it is determined that normal operation is in progress. The determination unit 111 calculates the conversion coefficient K (t) from the current range set value Irange and the current current command value Ic (t) using the above equation (1) (step S25).

The determination unit 111 determines whether the absolute value | K (t) | of the conversion coefficient K (t) is 1 or more and 2 or less (step S26).

Here, the current command value Ic (t) is commanded by the microcomputer 101 within the range of the following equation (3).

−Irange ≤ Ic (t) ≤ + Irange ・ ・ ・ Equation (3)

According to the above equations (1) and (3), the conversion coefficient K (t) is a value from −∞ to -1 and from +1 to +∞. Here, FIG. 7 illustrates the relationship between the waveform of the white noise electrical stimulation and the conversion coefficient K (t). As can be easily understood from the figure, the absolute value | K (t) | of the conversion coefficient determined in step S26 is 1 or more and 2 or less, that is, the current command value Ic (t), that is, the noise stimulation current. It means that the value is in the range larger than 1/2 of the current range.

The determination unit 111 uses the above equation (2) to set the maximum output voltage VoutMax (t) only when the current command value of the noise electrical stimulation is larger than 1/2 of the current range (step S26: Yes). The calculation is performed, and the calculated value is integrated into the variable Sum (step S27). Then, the value of the count variable Count is decremented by 1 (step S28).

The determination unit 111 repeats the above-mentioned disconnection determination process (step S23) and the maximum output voltage integration process (steps S27 and S28) a predetermined number of times (for example, eight times) (step S29). When the determination unit 111 determines that the value of the count variable Count has become 0 (step S29: Yes), the determination unit 111 divides the variable Sum by the initial value 8 of the count variable Count (step S30) to obtain the maximum output voltage average VoutMaxMean. (Step S30).

The determination unit 111 may multiply the voltage Vout_d between the electrodes 11 and 12 by the conversion coefficient K (t) to obtain the average of the maximum output voltages.

Then, the determination unit 111 determines the level of the obtained maximum output voltage average VoutMaxMean in, for example, five steps (step S31).

Then, the microcomputer 101 displays the output level determined by the determination unit 111 on the display unit 112 (step S32).

The output level display function of such processing can prompt the user to reattach the electrodes 11 and 12 due to poor adhesion before the GVS device 1 determines that the disconnection error occurs, and avoids interruption of electrical stimulation in advance. can do.

1 GVS device 10 controller 11 electrode (out side)
12 Electrodes (return side)
13 Internal resistance 101 Microcomputer 102 EPROM
103 RAM
104 Setting operation unit 105 DA conversion unit 106 Level shift circuit unit 107 Voltage-current conversion unit 108 Current detection resistor 109 Level shift circuit unit 110 AD conversion unit 111 Judgment unit 112 Display unit 113 Timer

Claims (4)

A vestibular electrical stimulator that applies noise electrical stimulation to the patient's peripheral vestibular system via a pair of electrodes in close contact with the patient's skin.
A vestibular electrical stimulator comprising a determination unit for determining the output level of the noise electrical stimulation output from the electrode and a display unit for stepwise displaying the determined output level. The vestibular electrical stimulator according to claim 1, wherein the determination unit measures the output voltage of the noise electrical stimulus for a predetermined period of time and determines the output level based on the measured maximum value of the output voltage. A current range storage unit that stores a current range setting value set for each patient and a current conversion unit that outputs a current according to a current command value that forms a waveform of the noise electrical stimulation from the electrode are provided.
Here, the conversion coefficient K is
Conversion coefficient K = current range set value / current command value shall be defined.
The determination unit calculates the estimated maximum output voltage of the noise electrical stimulation by multiplying the output voltage of the noise electrical stimulation by the conversion coefficient K, and determines the output level based on the maximum output voltage. The vestibular electrical stimulator according to claim 1. The vestibular electrical stimulator according to claim 3, wherein the determination unit determines the output level based on the average of the maximum output voltages when the conversion coefficient K is 1 or more and a predetermined value or less.

Images