WO2009012918A1

WO2009012918A1 - Pain therapy device

Info

Publication number: WO2009012918A1
Application number: PCT/EP2008/005792
Authority: WO
Inventors: Jacques Elias; Heinz Busch
Original assignee: Prontomed Gmbh
Priority date: 2007-07-20
Filing date: 2008-07-16
Publication date: 2009-01-29
Also published as: DE102007034065A1; DE102007034065B4; EP2180919A1

Abstract

The invention relates to a pain therapy device, which has a stimulating electrode (10) for placing on a point that is painful to pressure, a hand electrode (12), a generator (14) for generating an electric voltage between the stimulating electrode (10) and the hand electrode (12) and a control device (16) for activating the generator (14), wherein the electric voltage has at least one predetermined and/or adjustable signal waveform. According to the invention, it is provided that the electric voltage is formed as a square-wave voltage, which is defined by an upper threshold value (Umax), a lower threshold value (Umin), a rising edge (52) and a falling edge (54).

Description

Pain therapy device

description

The invention relates to a pain therapy device according to the preamble of claim 1.

The pain therapy devices that provide a pulsating DC voltage in the low-voltage range, have been developed recently. The design effort for such a pain therapy device is relatively low. Via a stimulation probe, the pulsating DC voltage is applied to a painful point. The DC voltage oscillates between a maximum voltage and a minimum voltage. At certain frequencies, pain relief can be achieved in this way.

From DE 10 2004 027 930 Al a pain therapy device is known which has two generators. Between a stimulation probe and a hand probe, the pulsating DC voltage is applied. The first generator generates a pulsating DC voltage with a frequency of 2800 Hz. The second generator generates a pulsating DC voltage with a frequency of 8000 Hz. Optionally, one of the two generators can be activated manually. Studies have shown that the frequencies of 2800 Hz and 8000 Hz have an analgesic effect in a number of indications.

The invention has for its object to provide an improved pain therapy device of the type mentioned.

This object is achieved by the subject matter of claim 1.

According to the invention it is provided that the electrical voltage is formed as a square-wave voltage, which is defined by an upper threshold, a lower threshold, a rising edge and a falling edge. Due to the square-wave voltage increases during the rising edge, the voltage between the stimulation electrode and hand electrode very quickly and drops accordingly quickly during the descending flank. These rapid changes in voltage cause a very short but relatively high current pulse. As a result, a therapeutic effect is achieved in many cases.

According to the current state of knowledge, certain electrical potential thresholds must be exceeded in order to stimulate chemical reactions in the ends of the nerves. Since the ohmic resistance of the skin of the human body is very high, but its capacity is relatively low, this electrical potential can be transmitted capacitively to the human body only with a rapid change in potential at low voltages. The square-wave voltage thus creates the required potential to ensure the chemical reactions in the nerve cells.

Preferably, the square-wave voltage is defined by an upper signal duration for the upper threshold and a lower signal duration for the lower threshold. For example, in the square-wave voltage, the upper signal duration and the lower signal duration are the same. Alternatively, in the rectangular voltage, the upper signal duration and the lower signal duration may be different in length. It is provided that the ratio between the upper and lower signal duration is predetermined and / or adjustable. The ratio between the upper and lower signal duration can also vary, for example, from a square pulse to the next rectangular pulse or after a certain number of square pulses.

For example, the square-wave voltage can be defined by a predetermined and / or adjustable number of rising edges within a certain period of time. Studies have shown that the number of rising edges within a given period of time in terms of therapeutic effect of importance. Furthermore, the square-wave voltage can be defined by a predetermined and / or adjustable frequency. It has been shown that certain frequencies or frequency cycles have a special therapeutic effect.

The upper threshold of the square-wave voltage is for example between 4 V and 16 V, in particular between 6 V and 12 V and preferably between 7 V and 10 V. These voltages can be provided on the one hand with conventional and inexpensive voltage sources and on the other hand are sufficient for the desired therapeutic effects , Basically, the upper threshold can be up to 52V. In this area, no health risk to the patient is to be feared.

Furthermore, it can be provided that the lower threshold value is between -2 V and 4 V, in particular between -1 V and 2 V, preferably 0 V. The lower threshold can be up to -52V in principle. There is no health risk to the patient in this area.

The difference between the upper threshold and the lower one

Threshold should be at least 0.2V. For example, the maximum value for the difference between the upper threshold and the lower threshold may be 18V, and preferably 10V.

In the preferred embodiment, it is provided that the slope of the rising edge between 10 ⁹ V / s and 10 ⁶ V / s, in particular between 3 * 10 ⁸ V / s and 3 * 10 ⁶ V / s, preferably between 10 ⁸ V / s and 10 ⁷ V / s. These values can be used to achieve the desired therapeutic effects. The rising edge causes a current pulse, which is higher, the steeper the edge is.

Preferably, the slope of the trailing edge is less than 5 * 10 ⁶ V / s. In addition, the slope of the trailing edge may be less than the slope of the rising edge. It can be used in different cases. may be beneficial that the rising edge is steeper than the falling edge and thereby the negative current pulse caused by the falling edge is smaller than the positive current pulse caused by the rising edge.

In one operating mode, the predetermined frequency is 2800 Hz. This frequency can be used in particular for neuralgia, neuralgic pain, pain in paresis and hay fever,

The square-wave voltage can also be defined by the number of rising edges within a certain time unit instead of the frequency. In the above case, 2800 rising edges would be provided per second. The time intervals between successive rising edges may be the same or different.

In another mode, the predetermined frequency is 8000 Hz. This frequency is suitable for pain of a general nature. In particular, the frequency of 8000 Hz can be used for joint pain, for example in arthrosis and arthritis. This frequency is also suitable for the treatment of headaches.

The aforementioned operating mode can also be defined by 8000 rising edges per second. Also in this case, the time intervals between successive rising edges may be the same or different.

For example, each mode is defined by a cycle having one or more consecutive time intervals. Each time interval is characterized by the waveform, frequency, thresholds, edges, and / or other parameters for the voltage between the stimulation electrode and the hand electrode. This allows to set or program a plurality of modes in which the voltage signal is changed within the cycle becomes. In this way, the application possibilities of the pain therapy device are extended.

For example, in one mode for a first time interval, a square wave voltage having a predetermined frequency and for a second time interval a constant DC voltage having a predetermined voltage is defined or definable. In this case, the constant voltage is preferably 0 V. In this way, it is ensured that the square-wave voltage is not applied continuously, but also a treatment break is taken.

In a preferred embodiment of the invention, a square-wave voltage having a predetermined starting frequency is provided in an operating mode for a first time interval and twice the frequency of the respective preceding time interval for further time intervals. The starting frequency is for example 330 Hz. Due to this frequency doubling, pain relief can be achieved.

Preferably, the frequency doubling cycle comprises six time intervals of equal duration. The length of the cycle may be, for example, one minute. A typical frequency sequence includes the frequencies 330 Hz, 660 Hz, 1320 Hz, 2640 Hz, 5280 Hz and 10560 Hz.

For the square-wave voltage, the upper signal duration and the lower one

Signal duration be the same length. Alternatively, the upper signal duration and the lower signal duration may also be different lengths.

Preferably, the controller is programmed or programmable. As a result, the existing operating modes can also be modified later. In addition, it can be added to other modes with little effort. Furthermore, the pain therapy device may have an input device which is provided for setting the operating mode and / or activating the generator. Activating the generator starts a cycle and runs it automatically. Thus, the treating person or the patient himself can operate the pain therapy device in a simple manner.

For safety reasons and to protect the patient, the pain therapy device may comprise a current limiting device, which is provided for automatically limiting the current between the stimulation electrode and the hand electrode to a predetermined maximum current. Preferably, there are two current limits. The predetermined maximum current during the rising edge is for example 10 mA. For example, the limit averaged over the signal is 0.05 mA.

Finally, it can be provided that the pain therapy device has a shutdown device for automatically switching off the pain therapy device after a predetermined period of time. On the one hand, this is a safety measure, so that the patient can not accidentally be exposed to square-wave voltage over a longer period of time. On the other hand, this prevents unnecessary power consumption. In this case, the predetermined period of time may be between one and three minutes, preferably two minutes.

Other features, advantages and particular embodiments of the invention are the subject of the dependent claims.

Hereinafter, preferred embodiments of the invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 is a schematic block diagram of a preferred embodiment of a pain therapy device according to the invention, Fig. 2 is a schematic view of the preferred embodiment of

Pain therapy device according to the invention,

Fig. 3 is a schematic view of a waveform of the pain therapy device according to the invention

Rectangular voltage, and

Fig. 4 is a schematic view of the electric current between two electrodes of the pain therapy device according to the invention as a function of time.

In Fig. 1 is a schematic block diagram of the pain therapy device according to a preferred embodiment of the invention. The pain therapy device comprises a stimulation electrode 10 and a hand electrode 12. The stimulation electrode 10 is made of an electrically conductive material, for example made of stainless steel. Furthermore, the stimulation electrode 10 is formed as a thin rod. The hand-held electrode 12 is also made of an electrically conductive material. Preferably, the hand electrode 12 is formed as a surface piece.

The pain therapy device comprises a generator 14 whose output is coupled to the stimulation electrode 10. On the input side, the generator 14 is coupled to a control device 16. The control device 16 has a microprocessor and a working memory. Furthermore, the pain therapy device comprises a display device 18, an input device 20 and a clock generator 22. The display device 18, the input device 20 and the clock generator 22 are coupled to the control device 16. In addition, the pain therapy device has a detection device 24 which is coupled on the input side with the stimulation electrode 10 and on the output side with the control device 16. Finally, the pain therapy device included a voltage source which is not shown in FIG. As a voltage source, for example, one or more batteries or accumulators may be provided. The supply voltage for the pain therapy device is preferably between 3 V and 10 V. In the preferred embodiment, the supply voltage is 4.5 V.

The stimulation electrode 10 is provided for application to pressure-sensitive or pressure-painful points on the body of the patient. The hand electrode 12 is usually touched by the treating person. If the circuit is not closed, appears on the display device 18, a corresponding icon.

At the input device 20, the treating person can select from several operating modes. The possible operating modes are explained in more detail below. The treating person can set further parameters at the input device 20 and start the treatment process. The signals from the input device 20 are processed by the control device 16 so that the current operating state and further parameters are displayed by the display device 18 and the generator 14 generates a square-wave voltage or constant DC voltage in accordance with the operating state.

The detection device 24 is for detecting the voltage and the

Current between the stimulation electrode 10 and the hand electrode 12 and sends corresponding signals to the controller 16, which are further processed there. The detected voltages and currents may be displayed by the display device 18. The control device 16 includes a current limiting function so that the current between the stimulation electrode 10 and the hand electrode 12 does not exceed a predetermined value. In this particular embodiment, the current is limited to 10 mA during the rising edge. The limit averaged over the signal is 0.05 mA.

The clock generator 22 is provided to provide the digital part of the controller 16 and the generator 14 with clock signals. FIG. 2 shows a schematic view of the preferred embodiment of the pain therapy device according to the invention. The pain therapy device comprises a housing 30, in the interior of which the control device 16, the generator 14, the detection device 24 and the clock generator 22 are arranged. The housing is formed substantially cuboid. At a front side of the housing 30, the stimulation electrode 10 is attached. The stimulation electrode 10 is rod-shaped and extends away from the housing 30 like an antenna. In this embodiment, the stimulation electrode 10 has a rounded tip and is made of a biocompatible stainless steel.

The pain therapy device may include a needle mountable to the stimulation electrode 10. The needle is intended for invasive treatment. Alternatively, the stimulation electrode 10 may be formed as a needle.

The display device 18, the hand electrode 12 and the input device 20 are located on a large-surface upper side of the housing 30. The display device 18 has a display 26 and a light-emitting diode 28 in this specific embodiment. In particular, letters, numbers, symbols and graphic elements are shown or representable on the display 26. The hand electrode 12 is formed as a surface piece and arranged between the display device 18 and the input device 20. The hand electrode 12 is made of an electrically conductive material.

The input device 20 is formed in this example as an eight-key keyboard. A switch 32 is provided for turning on and off the pain therapy device. Two program selection keys 34 and 36 are provided for setting a specific mode, wherein on a menu, the first program selection key 34 in the forward direction and the second program selection key 36 in the reverse direction switches. Two intensity buttons 38 and 40 are provided for adjusting the voltage between the stimulation electrode 10 and the hand electrode 12, the first one being the second one Intensity button 38 increases the voltage and the second intensity button 40 reduces the voltage. An acoustic button 42 is provided for activating and deactivating acoustic signals. A start key 44 is provided for activating a cycle of the set mode. To stop the cycle, a stop button 46 is provided.

In operation, the stimulation electrode 10 is applied to the patient at the painful point. The hand electrode 12 is touched either by the patient or by the treating person by hand. In the latter case, the treating person should touch the patient directly or indirectly. Even a self-treatment of the patient is possible. In this case, the stimulation electrode 10 is applied to the pressure-painful point and touched the hand electrode 12 directly or indirectly from the patient.

Fig. 3 shows a schematic view of a preferred square wave voltage as generated by the pain therapy device according to the invention. The square-wave voltage is characterized by an upper threshold Umax, a lower threshold Umin, a rising edge 52 and a falling edge 54. Furthermore, the square-wave voltage is defined by the frequency or the number of rising edges per unit time. Another characteristic quantity is the upper signal duration Tl for the upper threshold Umax and the lower signal duration T2 for the lower threshold Umin.

In this particular embodiment, the upper threshold is 9V. Typically, the upper threshold is between 4V and 16V. The lower threshold in this embodiment is 0V but may be between -2V and 4V. These voltages can be provided on the one hand with conventional and inexpensive voltage sources and on the other hand are sufficient for the desired therapeutic effects. In principle, the upper threshold can be up to about 52 V at maximum and the lower threshold can be up to about -52 V so that there is no health risk for the patient.

In this embodiment, the slope of the rising edge 52 is between 10 ⁸ V / s and 10 ⁷ V / s. To achieve the desired therapeutic effects, the slope of the rising edge 52 should be approximately between 5 * 10 ⁶ V / s and 10 ⁶ V / s.

Preferably, the slope of the trailing edge 54 is greater than 2.5 * 10 ⁶ V / s. It may be advantageous in different cases that the negative current caused by the falling edge is smaller than the positive current caused by the rising edge.

The ratio between the upper signal duration Tl and the lower signal duration T2 may be fixed or variable. The variation can also occur from pulse to pulse or after a certain number of pulses. Likewise, the ratio between the upper and lower signal durations T1 and T2 can also be changed at the transition between two successive time intervals. Tl should be greater than 1 μs.

FIG. 4 shows a schematic diagram of the electrical current between the stimulation electrode 10 and the hand electrode 12 as a function of time. The rising edge 52 of the square wave voltage causes a momentary positive current pulse 56. Accordingly, the falling edge 54 of the square wave voltage causes a momentary negative current pulse 58. The maximum current at the positive current pulse 56 is about 10 mA in this example. The positive current pulse 56 lasts approximately between 0.2 μs and 1 μs. With the negative current pulse 58, the maximum current is lower than with the positive current pulse 56. The negative current pulse 58 lasts longer, for example 4 .mu.s, than the positive current pulse 56. This can be achieved by a temporal attenuation. Several modes of operation that are practicable with the preferred embodiment of the pain therapy device according to the invention will now be described.

In the first mode of operation, a square wave voltage with a frequency of 2800 Hz is provided between the stimulation electrode 10 and the hand electrode 12. One cycle of the first mode comprises at least one time interval in which the square-wave voltage with the frequency of 2800 Hz is applied. Optionally, a further time interval may be provided in which a constant DC voltage is applied between the stimulation electrode 10 and the hand electrode 12. Preferably, the constant DC voltage is 0 V. The square-wave voltage oscillates between an upper threshold Umax and a lower threshold Umin. For example, the lower threshold Umin corresponds to the constant DC voltage. Preferably, the lower threshold Umin also equals 0 V. The upper threshold Umax is either pre-set or adjustable by the operator.

Switching off the square-wave voltage during the second time interval ensures that the patient and also the person being treated are only exposed to the square-wave voltage for a limited period of time.

The first mode of operation may now be designed such that one cycle comprises a multiplicity of time intervals. In this case, the square-wave voltage is present during the odd-numbered time intervals and the constant direct-current voltage, which is preferably 0 V, during the even-numbered time intervals.

With regard to its indications, the first mode of operation may be used in particular for neuralgia, neuralgia pain, pain in paresis and hay fever. Especially with neuralgic pain in the facial area and extremities, the first mode of operation can be used successfully. A second mode is very similar to the first one in qualitative terms. In the second mode, a square wave voltage of 8000 Hz is provided between the stimulation electrode 10 and the hand electrode 12. A cycle of the second mode of operation also includes at least one time interval in which the square-wave voltage with the frequency of 8000 Hz is applied. Optionally, a further time interval can be provided, in which the constant DC voltage is applied between the stimulation electrode 10 and the hand electrode 12. Preferably, the constant DC voltage is 0 V. The square-wave voltage oscillates in the second mode between an upper threshold Umax and a lower threshold Umin. For example, the lower threshold Umin corresponds to the constant DC voltage. Preferably, the lower threshold Umin is also 0 V. The upper threshold Umax is either set in advance or can be set by the operator.

Switching off the square-wave voltage during the second time interval ensures that the patient and also the person being treated are exposed to the pulsating DC voltage only for a limited period of time.

The second mode of operation can now also be designed such that the square-wave voltage is applied during the odd-numbered time intervals and the constant DC voltage is applied during the even-numbered time intervals, the constant DC voltage preferably being 0 V.

The second mode can be used for many indications. In general, the second mode is suitable for general pain. In particular, the second mode of operation can be used for joint pain, for example in the case of arthrosis and arthritis. The second mode is also suitable for the treatment of headaches.

In a third mode, the cycle includes at least six time intervals. During the first time interval, a pulsating DC Voltage with a predetermined starting frequency Fl between the stimulation electrode 10 and the hand electrode 12 is applied. At the beginning of the second time interval, the frequency of the square-wave voltage is doubled. This process is repeated at the beginning of the third to sixth time intervals. Thus, the frequencies in the second to sixth time intervals are twice as large as the frequency in the previous time interval.

In a preferred embodiment of the third mode of operation, the starting frequency is Fl = 330 Hz. In the subsequent time intervals, the frequencies are F2 = 660 Hz, F3 = 1320 Hz, F4 = 2640 Hz, F5 = 5280 Hz and F6 = 10560 Hz entire cycle one minute and each time interval lasts 10 seconds.

Optionally, a seventh time interval with a constant voltage, preferably 0 V, can then be provided. This ensures that a treatment break is taken and the patient is not permanently exposed to the square wave voltage.

The third mode of operation can be used, for example, for pain caused by circulatory disorders. In addition, the third mode of operation can also treat circulatory disorders themselves.

The effect of the pain therapy device according to the invention is due to the fact that pain is alleviated in certain frequency ranges. The human body can be considered as an equivalent circuit comprising a resistive element and a capacitor element connected in parallel thereto. In this case, the virtual resistance element has a resistance of about 500 kΩ to 2 MΩ, which would allow only a current in the μA range. The capacitance of the virtual capacitor element is approximately between 20 pF and 100 pF. During the rising edges of the square-wave voltage, a short-term current pulse is generated whose maximum height is approximately 10 mA. This current pulse lasts about 0.2 μs to 1 μs. This surge is repeated at regular and / or irregular intervals according to the frequency or the number of rising edges.

In another mode, the pain therapy device may be provided for locating acupuncture points. Usually, special devices are used to detect acupuncture points, which detect the skin resistance. Using a measuring tip, a DC voltage is applied to the skin and the current is measured via a series-connected resistance element. The measuring tip is guided over the skin surface and the skin resistance is recorded at various points. This requires a certain minimum contact pressure.

At the acupuncture points, the electrical resistance is lower than at other points, so that in this way the acupuncture points can be found. However, the strength of the contact pressure and the moisture of the skin influence the contact resistance and can therefore lead to misinterpretations. By contrast, the influence of skin moisture plays a lesser role in the measurement of the capacitive contact resistance, so that the measurement accuracy is increased with this method.

Preferably, voltage pulses having a relatively short rising edge are used. The current flowing during the rising edge is due to the capacitive transfer. Once the maximum voltage is reached, a DC current flows over the entire pulse length. This makes it possible to detect both the capacitive resistance on the skin and the ohmic resistance at the same time. The measuring tip does not have to be pressed on, but can be passed over the skin with a gentle touch.

In addition, it is possible to vary the rising edge and thus capture any resonances. With high The resonance frequency at one acupuncture point will differ from the resonance frequencies at the other skin point.

The pain therapy device according to the invention can also have an interface, so that it can be connected to a personal computer or a notebook. When the pain therapy device has the interface, the display device 18 and the input device 20 are not necessarily required in the pain therapy device. The functions of the display device 18 and the input device 20 can also be taken over by the personal computer or notebook. The functions of the control device 16 can also be performed by the personal computer or notebook.

LIST OF REFERENCE NUMBERS

10 stimulation electrode

12 hand electrode

14 generator

16 control device

18 display device

20 input device

22 clock generator

24 detection device

26 display

28 LED

30 housing

32 switches

34 first program selection key

36 second program selection key

38 first intensity key

40 second intensity key

42 Acoustic key

44 Start button

46 stop button

52 rising edge

54 descending flank

56 positive current pulse

58 negative current pulse

Umax upper threshold

Umin lower threshold

Tl upper signal duration

T2 lower signal duration

Imax maximum current

Claims

claims

A pain therapy device comprising: a stimulation electrode (10) for application to a pressure-painful point, a hand electrode (12), a generator (14) for generating an electrical voltage between the stimulation electrode (10) and the hand electrode (12) , and - a control device (16) for driving the generator (14), wherein the electrical voltage has at least one predetermined and / or adjustable waveform, characterized in that the electrical voltage is formed as a square wave voltage, which by an upper threshold (Umax ), a lower threshold (Umin), a rising edge (52) and a falling edge (54).

2. pain therapy device according to claim 1, characterized in that the square-wave voltage by an upper signal duration (Tl) for the upper threshold (Umax) and a lower signal duration (T2) for the lower threshold (Umin) is defined.

3. pain therapy device according to claim 1 or 2, characterized in that the square-wave voltage by a predetermined and / or adjustable number of rising edges (52) within a certain period of time and / or by a predetermined and / or adjustable

Frequency is defined.

4. pain therapy device according to one of claims 1 to 3, characterized in that the upper threshold value (Umax) is between 4 V and 16 V, in particular between 6 V and 12 V, preferably between 7 V and 9 V, and the lower threshold value (Umin) is between -2 V and 4 V, in particular between -1 V and 2V, preferably 0V.

5. pain therapy device according to one of claims 1 to 4, characterized in that the steepness of the rising edge (52) between 10 ⁹ V / s and 10 ⁶ V / s, in particular between 3 * 10 ⁸ V / s and 3 * 10 ^6th V / s, preferably between 10 ⁸ V / s and 10 ⁷ V / s, and the slope of the trailing edge (54) is preferably less than the slope of the rising edge (52).

6. pain therapy device according to one of claims 3 to 5, characterized in that the predetermined frequency is 2800 Hz or 8000 Hz.

7. Pain therapy device according to one of the preceding claims, characterized in that the control device (16) is provided for controlling at least one predetermined and / or adjustable mode, wherein preferably the control device (16) is programmed or programmable.

8. pain therapy device according to claim 7, characterized in that the operating mode is defined by a cycle comprising a time interval or a plurality of successive time intervals, wherein preferably the time interval is associated with a predetermined and / or adjustable waveform.

9. pain therapy device according to claim 8, characterized in that in the operating mode for a first time interval, a predetermined starting frequency and for further subsequent time intervals twice the frequency of the respective preceding time interval is provided, wherein the starting frequency is preferably 330 Hz.

10. Pain therapy device according to claim 9, characterized in that the cycle comprises six time intervals of equal duration and the length of the cycle is for example between 30 seconds and 100 seconds, preferably one minute.

11. pain therapy device according to claim 9 or 10, characterized in that the frequencies in the successive time intervals 330 Hz, 660 Hz, 1320 Hz, 2640 Hz, 5280 Hz and 10560 Hz amount.

12. Pain Management device according to one of claims 2 to 11, characterized in that the upper signal duration (Tl) and the lower signal duration (T2) are equal ^to l g or different lengths, wherein preferably the upper

Signal duration (Tl) is greater than 1 μs.

13. Pain therapy device according to one of the preceding claims, characterized in that the pain therapy device has an input device (20) which is provided for setting the operating mode and / or activating the generator (14).

14. pain therapy device according to any one of the preceding claims, characterized in that the pain therapy device on a current limiting device for automatically limiting the current between the stimulation onselektrode (10) and the hand electrode (12) to a predetermined maximum current (Imax), wherein during the rising edge (52), the predetermined maximum current (Imax), for example, between 5 mA and 15 mA, preferably 10 mA and the Ü over the signal averaged predetermined maximum current (Imax), for example between 0.005 mA and 0.1 mA, preferably 0.05 mA.

15. pain therapy device according to any one of the preceding claims, characterized in that the pain therapy device comprises a shutdown device for automatically switching off the pain therapy device after a predetermined period of time, wherein the predetermined period is for example between one and three minutes, preferably two minutes.