JP4178762B2 - Magnetic stimulator using litz wire coil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coil stimulation apparatus for performing magnetic therapy by generating a variable magnetic field that induces eddy current in a living body by supplying a pulse current to a coil using a litz wire.
[0002]
[Prior art]
As a treatment device for electrical urinary incontinence, the applicant of the present application has replaced the well-known electrical stimulation device in which stimulation electrodes are attached to a patient and an electrical pulse is applied to treat urinary incontinence. According to Kaihei 9-276418 (US Pat. No. 5,984,854), a urinary incontinence treatment device by magnetic stimulation was proposed. In this device, a magnetic stimulation coil is attached to a coil fixture that is placed indoors, and a pulsed magnetic flux is repeatedly generated in the coil, and the magnetic flux is applied to a region in the range from the patient's waist to the lower limb. The pelvic floor muscle group, pudendal nerve, etc. are stimulated with eddy currents. Also, the present applicant has previously proposed a magnetic stimulation type urinary incontinence treatment coil as disclosed in JP-A-10-234870.
In addition, various coil devices have been developed in recent years as magnetic therapy.
[0003]
[Problems to be solved by the invention]
However, the conventional coil is a general electric wire or a copper pipe (hollow conductor). For this reason, the alternating current effective resistance of the conventional coil was large, and the electrical loss was large. As a result, even if the number of times of use is small, the heat generated by the coil increases as the device continues to be used, the coil temperature rises, and there is a risk of burns. Therefore, a conventional coil requires a large capacity cooling device.
[0004]
An object of the present invention is to provide a practical magnetic stimulation apparatus that can efficiently stimulate various magnetic treatment sites or diagnostic sites with low power consumption.
[0005]
[Means for Solving the Problems]
[0028]
The magnetic stimulation device according to claim 1 is a magnetic stimulation device that generates a magnetic field when a fluctuating magnetic field is generated in a patient's body and is magnetically stimulated so as to be treated. A Litz wire coil having an inductance of 10 to 50 μH, a power source for supplying a current that fluctuates to the Litz wire coil, an AC frequency of the current of 1.0 to 10 kHz, and a pulse width of the current Having a coil current peak value of 1000 to 8000 A and a stimulation frequency of 1 Hz to 100 Hz, and a drive control unit that drives the Litz wire coil. As a result, the heat generated in the coil can be suppressed and it can be driven safely, and noise caused by the collision between the coil portions can be prevented.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The Litz wire coil portion for magnetic treatment of the muscle and nervous system of the present invention will be described. FIG. 1 shows a cross-sectional view of the litz wire coil 6. The element wire 1 is formed by covering a conductor portion 2 with an insulating layer 3. The first litz wire 4 is formed by twisting seven strands 1 and covering the outer periphery with an insulating layer 11. The second litz wire 5 is formed by twisting seven first litz wires 4 and covering the outer periphery with an insulating layer 12. The litz wire coil 6 is formed by twisting seven second litz wires 5 and covering the outer periphery with an insulating layer 13. The insulating layers 11, 12, and 13 are made of glass fiber tape, plastic tape, or rubber tape. Further, an insulating tube may be used instead of tapes, or a flexible adhesive such as silicone may be used. The insulating layers 11 and 12 can be omitted.
[0030]
In general, when a high-frequency current is applied to a conducting wire, a skin effect occurs, the current concentrates on the surface, the effective resistance increases, and the electrical loss increases. The depth δ of the skin is determined by the current frequency, as shown by the following equation, and the depth decreases as the frequency increases.
δ = {1 / (πfμσ)} 1/2
μ: permeability, σ: electrical conductivity, f: frequency
The effective resistance increases greatly when the radius of the conducting wire is greater than or equal to δ, and the size of the space around which the coil is wound, while referring to the above relational expression, the conductor portion 2 of the strand 1 of the litz wire coil 6 It is preferable to determine the diameter, the cross-sectional area of the litz wire coil 6 and the like.
[0032]
As the element wire 1 of the litz wire 6 shown in FIG. 1, a silver-plated, tin-plated or gold-plated annealed copper wire, an oxygen-free copper wire or a silver wire is used. The insulating material of the insulating layers 3, 11, 12, 13 of the litz wire 6 is particularly preferably porous PTFE or foamed FEP. As the wire covering material, it is preferable to use a porous material or a foamed material, for example, porous PTFE or foamed FEP. Alternatively, the insulating material is a general insulating material PTFE, porous PTFE, PFA, FEP, foamed FEP, ETFE, PVdF, a polyethylene film and a polyimide film, and further covered with porous PTFE or foamed FEP. A composite insulating material may be used. Alternatively, a composite insulating material may be used in which the covering material is polyethylene, nylon, vinyl chloride, or polyurethane, which is a general wire covering material, and the top or bottom thereof is covered with porous PTFE or foamed FEP. When driving by the pulse current of the coil unit the litz wire coil 6 formed by winding a coil 6 with each other collide with a force mutually attracted generated between the coil and the coil, Noise is arising at that time. To reduce or prevent noise its, 0.025～2.0Mm an insulating layer 3 of the wire 1 of the litz wire, the insulating layer 11 of the first litz wire 4 0.05 to 3 mm, the second Ritz The insulating layer 12 of the wire 5 may be 0.1 to 5 mm, the insulating layer 13 of the litz wire coil 6 may be 0.2 to 10 mm, and a soundproofing material or a sound absorbing material may be used for them.
[0033]
Depending on the level of the soundproofing effect, the use of a soundproofing material or sound absorbing material for a specific element wire or insulating layer may be omitted as appropriate. The diameter of the conductor part 2 including the strand 1 of the litz wire coil 6 is preferably 0.2 to 1.5 mm. Furthermore, from the viewpoint of avoiding the risk of concentration of magnetic flux and disconnection of the wire 1, about 0.3 mm is preferable.
[0034]
As the material of the soundproofing material / sound absorbing material used for the insulating layers 3, 11, 12, and 13, polyurethane foam, phenol foam, polyethylene foam, polystyrene foam, silicone, polysulfide, acrylic, modified polysulfide, acrylic urethane, Butyl rubber, SBR, glass wool, rock wool, felt, vinyl sheet, canvas canvas, and the like can be used. The property may be porous or porous. In order to avoid the risk of electric leakage, dry type is good.
[0035]
A first method of driving a therapeutic coil for a nervous system using a coil portion formed by winding a litz wire coil 6 is an AC frequency of 1.0 to 3.3 kHz, an inductance of 10 to 50 μH, and a pulse width of 300 μs to 1 ms. In addition, there is a driving method on condition that the coil current peak value is 2500 to 8000 A and the stimulation frequency is 15 to 50 Hz. This first driving method is mainly intended for treatment by a muscle training effect, and is particularly suitable for treatment of stress urinary incontinence and mixed urinary incontinence as urinary incontinence treatment.
According to this method, even when a coil current having a large peak value is passed, the skin effect can be reduced by using the litz wire, and the heat generation from the coil portion can be greatly reduced.
[0036]
In the treatment of stress urinary incontinence and mixed urinary incontinence, a coil device is placed below the buttocks to stimulate the magnetic flux to concentrate on the pelvic floor muscles, sacral and pudendal nerves.
[0037]
A second method of driving a coil for treating the nervous system using a coil portion formed by winding a litz wire coil 6 includes an AC frequency of 1.0 to 3.3 kHz, an inductance of 10 to 50 μH, and a pulse width of 300 μs to 1 ms. In addition, there is a driving method on condition that the coil current peak value is 1000 to 5000 A and the stimulation frequency is 50 to 100 Hz. This second drive system is mainly intended for treatment with muscle training effect or treatment with heat effect, especially knee osteoarthritis, low back pain, pain, stiff shoulder, spasticity, tumor (cancer), prostatic hypertrophy, gait Difficult, promote bone healing, good for joint treatment.
According to this method, the muscles tend to be stiffened by increasing the stimulation frequency, and the muscle stimulation becomes stronger by increasing the stimulation frequency. In addition, increasing the stimulation frequency increases the number of times per unit time that current flows in the living body, and increasing the pulse width increases the time that current flows in the living body. Since current is consumed to generate heat, this heat generation also provides a thermal effect. Muscles can be strengthened by repeated contraction and relaxation of muscles.
Note that muscle training may be performed by burst magnetic stimulation in order to avoid muscle fatigue due to tetanus.
[0038]
In the treatment of knee osteoarthritis, when the coil device is placed tightly around the kneecap or around the kneecap and continuous or burst magnetic stimulation is applied, pain is eliminated or reduced.
[0039]
In the treatment of low back pain, the coil device can be placed close to the circumference of the waist and the pain can be eliminated or reduced by applying continuous or burst magnetic stimulation.
There are various causes of low back pain, but general causes are classified into orthopedics, internal medicine, aging or poor posture, and the like. By applying magnetic stimulation, blood circulation is promoted, muscle tone is reduced, and pain is reduced.
[0040]
In pain treatment, the coil device is applied to a site where pain occurs or acupressure points acting on the site, and continuous or burst magnetic stimulation is applied to eliminate or reduce pain.
The cause of pain is said to be that a pain-causing substance is produced as a result of stimulation or damage to the site where pain occurs. Applying magnetic stimulation produces a blood flow improvement effect, which leads to treatment.
[0041]
In the treatment of stiff shoulders, stiff shoulders can be reduced by arranging the coil device close to the shoulder or so that the magnetic force is applied to the acupressure point that works on the stiff shoulder.
[0042]
Spasticity is a state in which stretch reflex has a low threshold, tendon reflex is enhanced, and clonus is likely to occur, and is generally based on pyramidal disorders. Spasticity also occurs with stiffness.
The inhibitory effect of magnetic stimulation on spastic sites is explained by the principle of reciprocal innervation. The therapeutic condition is that the magnetic stimulation intensity is such that maximum contraction occurs during the antagonistic period of the spastic muscles, and a magnetic stimulation of 80 to 100 Hz is applied to the spastic muscles for about 15 to 30 minutes. The pulse width may be selected from 100 μs to 1 ms. Spasticity is alleviated by applying high frequency, continuous or burst magnetic stimulation to the antagonistic muscles of the spastic muscles with a coil device.
Spasticity includes spastic walking in which both lower limb muscles and crotch adductor muscles are spastic due to pyramidal disorders.
[0043]
In hyperthermia treatment of a tumor (cancer), a magnetic substance is bound to a drug that reacts specifically with a cancerous diseased tissue in the living body, and this magnetic substance-bound drug is injected into the living body to continuously or burst magnetically in the cancerous diseased part. Add stimulus. Cancer cells die because they are vulnerable to heat and lose their ability to grow.
Cancer cells are generally sensitive to heat, and when heated at 42 to 45 degrees, particularly around 43 degrees, they lose their ability to grow and are said to die. Therefore, the influence of the surrounding tissue is made as small as possible, and only the cancer tissue is selectively heated for treatment.
Cancer may be treated by applying a variable magnetic field from outside the body and heating only the cancer tissue. In this case, a highly conductive metal (platinum, gold, silver, stainless steel, etc.) is locally embedded in the cancer tissue in the deep part of the living body. Next, a variable magnetic field is applied from outside the body to heat the metal. During heating, a temperature sensor such as a thermistor may be inserted into the stimulation site to control the heating temperature. As a result, only the cancer tissue can be heated and cancer can be treated. There is an ultrasonic heating method as a non-invasive heating method. The ultrasonic heating method can warm a deep local tumor non-invasively without warming the epidermis surface.
However, ultrasonic waves are strongly reflected and refracted at boundaries where the acoustic impedance is greatly different, for example, at the air-soft tissue or bone-soft tissue interface. For this reason, the ultrasonic heating method is not suitable as a method for heating a gas-rich part such as the lungs or digestive organs or a part having a bone nearby.
[0044]
It is said that the cause of prostatic hypertrophy is aging and testicles. These causes are thought to change the hormonal environment in the body and cause prostate enlargement.
In the treatment for prostatic hypertrophy, the temperature of the enlarged portion can be increased by applying high-frequency, continuous or burst magnetic stimulation from the coil device to the prostatic hypertrophy portion.
There are two types of therapy: hyperthermia that makes the temperature warmed by treatment 45 degrees or less and high-temperature therapy that makes 45 degrees or more or 55 degrees or more.
[0045]
For the treatment of gait difficulties, the gait difficulty is eliminated or reduced by applying high-frequency, continuous or burst magnetic stimulation to the lower back, thigh, legs, knees, ankles or feet from the coil device. be able to.
[0046]
In bone fusion promotion and joint treatment, it can be applied to crush-type open fractures, fractures due to osteoporosis, femoral neck fractures, scaphoid fractures, infection pseudo-joints, congenital pseudo-joints, etc. Bone fusion can be promoted by applying high-frequency, continuous or burst magnetic stimulation to the joint site.
[0049]
A third method of driving a therapeutic coil for a nervous system using a coil portion formed by winding a litz wire coil 6 includes an AC frequency of 3.3 to 10 kHz, an inductance of 10 to 50 μH, a pulse width of 100 μs to 300 μs, a coil There is a drive system with a current peak value of 2500 to 8000 A and a stimulation frequency of 1 Hz to 10 Hz. This third driving system is mainly intended for treatment by nerve stimulation or diagnosis, in particular, treatment of Parkinson's disease, diagnosis of transcranial brain stimulation, treatment of epilepsy, nerve improvement treatment, urge urinary incontinence, blood Good for treatment of flow improvement. This condition is suitable for nerve stimulation because the pulse width is small. According to this method, even when the AC frequency is higher and the coil current peak value is higher than those of the first and second driving methods, the skin effect is reduced by using the litz wire, and the heating of the coil portion is performed. Can be reduced.
[0050]
In the treatment of Parkinson's disease, by arranging the coil device close to the head, symptoms specific to Parkinson's disease such as lightening the walking motion can be reduced.
Parkinson's disease occurs when nigrostriatal neurons are impaired and the secretion of dopamine, a neurotransmitter in the striatum, is impaired.
The main cause is thought to be dopamine biosynthesis disorder due to a decrease in tyrosine hydroxylase.
[0051]
A cored coil device for transcranial brain stimulation. According to this, by placing the coil device close to the head, it is possible to apply high-frequency, continuous or burst magnetic stimulation to the region to be stimulated in the brain without adverse effects other than the region to be stimulated in the brain. it can.
[0052]
In the treatment of epilepsy, epileptic seizures can be eliminated or reduced by applying high-frequency magnetic, continuous, or burst magnetic stimulation to the vagus nerve with a coil device.
[0053]
In the treatment of urge urinary incontinence, magnetic stimulation is stimulated to concentrate on the pelvic floor muscle group, sacral nerve, pudendal nerve and the like.
[0054]
In blood flow improvement, the autonomic nerve is stimulated by applying high-frequency, continuous or burst magnetic stimulation to the part of the autonomic nerve where the blood flow has become worse (insufficient) than the coil device, and blood circulation is improved. Blood circulation is improved.
[0055]
As described above, the driving conditions for magnetic stimulation for magnetic therapy or diagnosis are determined according to various symptoms.
[0056]
FIG. 2 shows a therapeutic coil device for a nervous system comprising a coil portion 21 formed by winding the litz wire coil 6 shown in FIG. The coil portion 21 and the housing 22 are arranged so that there is a gap 23. By adopting a litz wire coil for the coil portion 21, heat generation is suppressed, and a gap 23 is provided so that heat generated in the coil portion 21 is directly transmitted to the living body epidermis and does not cause low-temperature burns. Since the peak value of the eddy current density generated by the fluctuating magnetic field generated by the coil unit 21 is closer to the coil unit than to the central axis side of the coil unit, the coil device is applied near the site to be stimulated. Further, the effective resistance can be reduced by suppressing the skin effect, and a large coil current can flow. As a result, since it is possible to apply a magnetic stimulus having a large stimulation intensity, a device for obtaining a large eddy current by concentrating the magnetic flux using the core becomes unnecessary. Thus, with the adoption of the litz wire, it is possible to make the specification without using the core.
[0057]
When used for urinary incontinence treatment, a coil device having a coil portion 21 is disposed below the buttocks to concentrate magnetic flux on the pelvic floor muscle group, sacral nerve, pudendal nerve, and the like. The number of turns of the litz wire coil 6 is preferably 5 to 100 turns.
FIG. 3 shows a numerical analysis of the distribution of eddy current density when the coil unit 21 stimulates the living body. The X axis is the distance from the coil center, the Y axis is the absolute value of eddy current density, and the Z value is the depth from the living body surface. As is clear from this figure, the maximum value of the eddy current density distribution is distributed in the normal direction of the coil. Therefore, the size of the coil should be determined in accordance with the size of the site to be stimulated. In the case of urinary incontinence treatment, the coil size is preferably about 40 to 160 mm because of the spread of the pelvic floor muscle group, sacral nerve, pudendal nerve and the like.
[0058]
As described above, the core may be used to concentrate the magnetic flux density and increase the stimulation efficiency.
FIG. 4 is an external view of the main part of the coil device provided with the core. As shown in FIG. 4, the core 8 is W-shaped. The core 8 is fixed to each other with one end of each of the two U-shaped core elements 8a and 8b oriented in the same direction. The core elements 8a and 8b are stacked iron cores or wound iron cores, and suitable materials include permendur, directional silicon steel plate, non-directional silicon steel plate, permalloy, sendust, pure iron or ferrite.
Although the core 8 is W-shaped, a cut core may be used as shown in FIG. 5, or the core of the product core may be E-shaped as shown in FIG. 6 instead of the W-shaped core.
In particular, when used for urinary incontinence treatment, a coil portion is preferably provided under or in the seat portion so that it can be seated as a chair regardless of whether the core is used or not.
[0059]
FIG. 7 shows the configuration of a drive device that drives the litz wire coil 6. This drive device will be described. The capacitor 31 is charged by the excitation power supply unit 32. The litz wire coil 6 is connected to the capacitor 31 via a circuit in which a thyristor 33 and a diode 34 are directed in opposite directions and connected in parallel. One end of the capacitor 31 is connected to the discharge unit 35. The control unit 36 is a circuit that controls the excitation power supply unit 32, the thyristor 33, and the discharge unit 35, respectively. The operation unit 37 is used to input various instructions and data necessary for control to the control unit 36.
[0060]
Next, the operation of the coil device configured as described above will be described. In this example, a method of stimulating with the maximum stimulation that the patient can tolerate by gradually increasing the stimulation intensity for the patient will be described as the maximum stimulation intensity method. When the treatment starts, the operator operates the operation unit 37 and gradually increases the voltage applied from the excitation power supply unit 32 to the capacitor 31 via the control unit 36. The controller 36 causes the one-phase waveform current to repeatedly flow through the litz wire coil 6 until the energy stored in the capacitor 31 is 40% of the maximum charge energy, and if the energy exceeds 40%, the two-phase waveform current is repeated. Make it flow.
Here, if the coil device is general-purpose, the operation unit 37 is configured so that a treatment target can be selected, and the appropriate stimulation condition described above is selected for the treatment target selected thereby. 36 may be controlled. In the case of a urinary incontinence treatment device, a switch for selecting whether the treatment target is abdominal pressure, urgency, or mixing is provided in the operation unit 37, and the control is performed under the appropriate stimulation condition described above for the selected treatment target. It may be controlled by the unit 36.
[0061]
In the case of a one-phase waveform, each part operates as follows. First, the control unit 36 supplies power to the capacitor 31 from the excitation power supply unit 32 to charge it, and then sends a control pulse to the thyristor 33 to turn on the thyristor 33. A current flows through 6. Next, the control unit 36 releases the electrical energy stored in the capacitor 31 through the discharge unit 35. Next, the control unit 36 turns off the thyristor 33. Thereafter, the above operation is repeated.
[0062]
In the case of a two-phase waveform, each part operates as follows. First, the control unit 36 supplies power to the capacitor 31 from the excitation power supply unit 32 to charge it, and then sends a control pulse to the thyristor 33 to turn on the thyristor 33. A current flows through 6. The capacitor 31 is charged again in reverse polarity. Next, the electrical energy stored in the capacitor 31 is discharged and flows through the litz wire coil 6 and the diode 34. Next, the control unit 36 turns off the thyristor 33. Thereafter, the above operation is repeated. FIG. 8 shows a waveform in the coil when the two-phase waveform is output by this driving.
[0063]
FIG. 9 shows a change in the electric field E at a certain point around the litz wire coil 6 in the case of a two-phase waveform. The period during which current flows through the litz wire coil 6 in the case of a single-phase waveform is set to 1/4 or 1/2 of the period T in the two-phase waveform by controlling the operation timing of the discharge unit 35 and the thyristor 33. Can do.
[0064]
In this way, the current flowing through the litz wire coil 6 is first made into a one-phase waveform, and then the current is made into a two-phase waveform in order to obtain a stimulation intensity of a predetermined level or more. In this way, the patient is accustomed to the stimulation during the one-phase waveform period, so that treatment can be performed without giving the patient a sudden stimulation.
[0065]
【The invention's effect】
According to the present invention, in a magnetic stimulation apparatus for performing treatment or diagnosis by stimulating with an eddy current induced by generating a variable magnetic field in a nerve, muscle, or diseased part, the Litz wire coil for generating the variable magnetic field is provided . Since the soundproofing material and the sound absorbing material are used for the insulating layer , it is possible to reduce the noise caused by the collision between the wound coils.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a litz wire coil 6 of the apparatus of the present invention.
2 is a cross-sectional view showing an example of a stimulation apparatus using the litz wire coil 6 shown in FIG.
FIG. 3 is a diagram showing an eddy current density distribution generated in a living body by magnetic stimulation generated from a coil.
4 is a view showing an example of a cored coil using the litz wire coil 6 shown in FIG. 1; FIG.
FIG. 5 is a view showing another example of a cored coil using the litz wire coil 6 shown in FIG. 1;
6 is a view showing another example of a cored coil using the litz wire coil 6 shown in FIG. 1. FIG.
FIG. 7 is a diagram illustrating a configuration of a driving device of a device that generates a variable magnetic field.
8 is a diagram showing a two-phase waveform output by a drive unit of the apparatus shown in FIG.
9 is a diagram showing an electric field generated by a driving unit of the apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Strand 2 Conductor part 3 Insulation layer 4 1st litz wire 5 2nd litz wire 6 litz wire coil 8 core 21 coil part 22 housing 23 gap 31 capacitor 32 excitation power supply part 33 thyristor 34 diode 35 discharge part 36 control part 37 Operation unit

Claims (1)

In a magnetic stimulation device that generates a fluctuating magnetic field in a patient's body and magnetically stimulates it for treatment,
A litz wire coil that generates a magnetic field by supplying a fluctuating current , forms an insulating layer with a soundproofing material or a sound absorbing material , and has an inductance of 10 to 50 μH;
A power source for supplying a fluctuating current to the Litz wire coil;
The Litz wire coil is driven in a range where the AC frequency of the current is 1.0 to 10 kHz, the pulse width of the current is 100 μs to 1 ms, the coil current peak value of the current is 1000 to 8000 A, and the stimulation frequency is 1 Hz to 100 Hz. A drive control unit;
A magnetic stimulation apparatus comprising:

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