WO2008089726A1

WO2008089726A1 - Implant for stimulating nerve cells

Info

Publication number: WO2008089726A1
Application number: PCT/DE2008/000071
Authority: WO
Inventors: Peter Tass; Walter DÖLL; Urban Schnell
Original assignee: Forschungszentrum Jülich GmbH; Anm Adaptive Neuromodulation Gmbh
Priority date: 2007-01-25
Filing date: 2008-01-16
Publication date: 2008-07-31
Also published as: DE102007003799A1

Abstract

The invention relates to an implant (80) having a receiver unit (81) for the wireless reception of control signals, a generator unit (82) connected to the receiver unit (81) for generating stimulating signals based on the control signals, und a stimulation unit (83) connected to the generator unit (82) for stimulating nerve cells using the stimulating signals.

Description

description

Implant for stimulation of nerve cells

The invention relates to an implant for stimulating nerve cells. Furthermore, the invention relates to an implantation comprehensive stimulation system and a method for stimulation of nerve cells.

For the treatment of neurological and psychiatric diseases, electrodes are implanted in the nervous system, especially in the brain. Conventional stimulation systems apply stimulation signals via the electrodes, for example permanently or on demand. In the case of permanent stimulation, there is usually no measurement of signals which are derived from the nervous system. In the demand-controlled stimulation form, measurement signals are recorded via electrodes implanted in the nervous system, which enable a detection of morbid events and their detection triggers a stimulation. The goal of both permanent and on-demand stimulation is to suppress morbid symptoms permanently or when they occur.

Against this background, an implant according to claim 1, a stimulation system according to claim 18 and a method according to claim 22 are given. Advantageous developments and refinements are specified in the subclaims.

According to one aspect of the invention, an implant comprises a receiving unit, a generator unit and a stimulation unit. The receiving unit wirelessly receives control signals, based on which the generator unit generates stimulation signals. The stimulation signals are used by the stimulation unit to stimulate nerve cells.

The implant may be part of a stimulation system according to another aspect of the invention. The stimulation system Further comprises a control device with a further generator unit for generating the control signals and a transmitting unit for wireless transmission of the control signals, which are then received by the receiving unit of the implant. The implant of the stimulation system may have the embodiments that are mentioned in the dependent claims to claim 1.

Another aspect of the invention relates to a method in which control signals are generated, transmitted and received wirelessly. Based on the received control signals, stimulation signals are generated with which nerve cells are stimulated.

The invention will be explained in more detail below by way of example with reference to the drawings. In these show:

Fig. 1 is a schematic representation of an implant 10 as an embodiment of the invention;

FIG. 2 is a schematic representation of a stimulation system 20 as a further embodiment of the invention; FIG.

3 is a schematic representation of a stimulation system 40 as a further embodiment of the invention;

4 is a schematic representation of a stimulation system 70 as a further embodiment of the invention;

5 shows a schematic representation of a stimulation and measuring electrode 100;

Fig. 6 is a schematic illustration of a pulse train 110; 7 shows a schematic representation of sequences 120 and 121 of pulse trains;

Fig. 8 is a schematic representation of a circuit

130 of an implant as a further embodiment of the invention; and

Fig. 9 is a schematic representation of a circuit 150 of an implant as a further embodiment of the invention.

In Fig. 1, an implant 10 is shown schematically as an embodiment of the invention. The implant 10 has a receiving unit 11, a generator unit 12 and a

Stimulation unit 13 on. During operation of the implant 10, the receiving unit 11 wirelessly receives control signals. The control unit supplies the generator unit 12, which generates stimulation signals on the basis of the control signals. The stimulation signals are used by the stimulation unit 13 for the stimulation of nerve cells, in particular of brain cells.

FIG. 2 schematically shows a stimulation system 20 as a further exemplary embodiment of the invention. The stimulation system 20 comprises a control device 30 in addition to the implant 10 described above. The control device 30 comprises a generator unit 31 for generating control signals and a transmitter unit 32 which transmits the control signals generated by the generator unit 32 wirelessly. The transmitted control signals are received by the receiving unit 11 and further processed as explained above.

FIG. 3 schematically shows a stimulation system 40, which represents a development of the stimulation system 20 shown in FIG. Both the implant 50 and the Control device 60 includes a transmitting and receiving unit 51 and 62, respectively, which allow bidirectional data exchange between the implant 50 and the control device 60. In the stimulation unit 53, a measuring unit is also integrated, which receives measurement signals from nerve cell associations, for example their neuronal activity. The measurement signals are transmitted wirelessly from the transmitting and receiving unit 51 to the transmitting and receiving unit 62 and then further processed in the generator unit 61.

In Fig. 4, a stimulation system 70 is shown during its intended operation. For this purpose, an implant 80 has been implanted in the head of a patient. The implant 80 consists of a coil 81 as a transmitting and receiving unit, a generator unit 82 and an electrode 83 as a stimulation and measuring unit, which has been implanted in the brain. A control device 90 has not been implanted in the patient and, like a hearing aid, is removably mounted behind the patient's ear ("behind the ear" BTE) .The control device 90 includes a generator unit 91 and a coil 92 configured as a transmitting and receiving unit. The coil 81 is typically implanted so as to be directly under the patient's skin, and the coil 92 is brought into proximity to the coil 81 from outside or directly applied to the coil 81. In the latter case, there is between the two coils 81 and only the skin of the patient The two coils 81 and 92 act as a transformer by which high frequency signals and electrical power are transmitted by induction.

While the controller 90 includes a rechargeable battery or, preferably, a replaceable battery for providing a supply voltage, the implant 80 typically does not include a replaceable battery to prevent frequent patient surgeries to replace the battery. Instead, the implant Did 80 an energy storage unit, for example in the form of a high-capacity charging capacitor or a rechargeable battery included. The accumulator relies on it being charged at regular intervals. The energy required for this purpose is supplied to the accumulator from the outside by wirelessly transmitting energy to the coil 81 from the coil 92 by means of induction. Batteries have a better volume-to-power ratio and are currently favored by accumulators in BTEs.

The control device 90 can be connected to a monitoring system to which the measurement signals recorded by the electrode 83 are transmitted telemetrically. By means of the monitoring system, a doctor can follow the success of the stimulation and the course of the disease on the basis of the measured neural activity and its reaction to stimulation. The monitoring of the neuronal activity also allows the modification of the stimulation parameters as a function of the measured neural activity.

The stimulation system 70 shown in FIG. 4 has an electrode 83 for stimulating and measuring neuronal activity. Alternatively, more than one electrode may be provided, the electrodes being implanted in the brain at different sites. A possible construction of such a stimulation and measuring electrode 100 is shown in FIG. The electrode 100 consists of an insulated electrode shaft 101 and at least one, for example, more than three or more than ten Stimulationskontakt- surfaces 102, which have been introduced into the electrode shaft 101. The stimulation pads 102 are made of an electrically conductive material, such as a metal, and are in direct electrical contact with the nerve tissue after implantation. Each of the stimulation contact surfaces 102 can be activated via its own supply line 103, or the recorded measurement signals can be dissipated via the supply lines 103. In addition to the Stimulation contact surfaces 102, the electrode 100 has a reference electrode 104, the surface of which is typically larger than that of the stimulation contact surfaces 102. The reference electrode 104 is used in the stimulation of the nerve tissue to generate a reference potential. Alternatively, one of the stimulation pads 102 may be used for this purpose.

In the following, the modes of functioning of the implants and stimulation systems shown in FIGS. 1 to 4 and the results achievable with these devices are explained. The devices presented here have been developed to treat neurological and psychiatric disorders by stimulation with electrical signals. In patients with neurological or psychiatric disorders, such as Parkinson's disease, essential tremor, dystonia, epilepsy, tremor as a result of multiple sclerosis and other pathological tremors, depression, obsessive-compulsive disorder, Tourette syndrome, post-stroke or tinnitus dysfunction, are nerve cell aggregates in circumscribed areas of the brain, e.g. Thalamus and basal ganglia, morbidly active, for example, excessive sync. In this case, a large number of neurons sync action potentials, that is, the involved neurons fire excessively synchronously. In the healthy patient, the neurons in these brain areas fire qualitatively differently, e.g. in an uncorrelated way.

The implants and stimulation systems described here are not concerned with suppressing symptoms through permanent or on-demand stimulation of the brain cells. Rather, temporary stimulation (eg over one to six or even up to twelve hours) with suitable types of stimulation transforms the nerve cell groups so that they tend to unlearn long-term or even permanently in the course of treatment the propensity to generate pathological activity. Surprisingly, the implants and stimulation systems described here cause long-lasting therapeutic effects even after a comparatively short time, even in severely affected Parsons patients with pronounced akmosis or pronounced on-off fluctuations, in which the standard high-frequency stimulation must also be applied permanently at night Stimulation during, for example, a few hours during the day. The therapeutic effects then continue for several days or even longer, with an accumulating effect of the therapeutic effect occurring during the treatment, so that the length of the required stimulation intervals can be even further reduced.

Due to the long-lasting therapeutic effects no duration stimulation has to be performed. In the case of continuous stimulation, the high charge input and the associated stimulation of surrounding tissue can lead to side effects, which can be very stressful for the patient. In addition, persistent irritation disrupts physiological (normal) information processing, since the stimulated nerve cell groups can not work "freely and undisturbed" but are permanently influenced in their discharge dynamics by the stimulator even at night, as patients are unable to move and turn from one side to the other and are thus unable to move to the bed, this affects the large group of patients with Akmese and Rigor Parkinson's, and in particular the Parkinson's patients with on-off fluctuations, in which phases with uncontrolled movements and phases with reduced mobility or even freezing (freezmg) alternate.

Another advantage of the invention is that it is possible to dispense with demand-controlled stimulation. Typically, in on-demand stimulation one or more types of pathological events are detected in the derived measurement signals. Once such events are detected, the stimulator applies stimuli which are either stereotyped or adapted to the particular type of event or its severity. This essentially requires that the detection of pathological events works. In fact, the detection of pathological events is sometimes difficult. Even more difficult or, for example in the case of epilepsy, even currently impossible to predict the occurrence of pathological events. The latter would allow the stimulator to stimulate with a certain lead time and thus possibly more efficiently. Adverse reactions may also occur in the case of demand-controlled stimulation, especially if, for example, stimulation is too frequent as a result of inadequate detection (too high a rate of false-positive events).

Another advantage of the implants described here is their comparatively small size, which is due to the fact that they are semi-implants in which a

Part of the device, namely the control device is not implanted. A smaller implant causes a smaller risk of infection and is less disturbing to the patient optically (cosmetically) and / or with regard to self-perception. Smaller implants also pose a lower risk of injury in the event of a fall or accident.

By placing the implant e.g. in mastoid, the stimulation electrodes can be laid along the rigid skull surface, i. they do not go through the moving one

Neck area as with breast implants. The associated advantages are improved healing, a mechanical relief of the electrode leads and a lower probability of surgical intervention for readjustment of the electrodes. A disadvantage usually associated with semi-implantable stimulation systems is overcome by the long-lasting therapeutic effects of the implants according to the invention. Since the devices according to the invention need not be worn at night due to their good stimulation effect, there can be no dislocations of the antenna during the night.

Long-lasting therapeutic remodeling of nerve cell associations - with the concomitant absence of symptoms - is achieved by stimulating such that the rate of synaptic coincidences, i. the frequency with which nerve cells connected via synapses simultaneously generate action potentials or bursts (groups of action potentials) is reduced. This unlearn the affected

Nerve associations surprisingly the tendency to manifest the pathological activity. Pathologically strong synaptic connections are diminished, and physiological (healthy) patterns of the synaptic connection of the neurons are formed again.

Surprisingly, this long-lasting effect also occurs when the stimulation is not directly effective. That under stimulation the symptoms do not necessarily disappear immediately; rather, they sound like e.g. Half an hour of stimulation slowly and increasingly from and then remain even after switching off the stimulator for a long time or even permanently away.

To achieve this effect, stimulation techniques must be used which cause the stimulated nerve cell assemblies to stop firing simultaneously (ie generate action potentials or bursts). For this purpose, stimuli are applied to the brain tissue via the stimulation contact surfaces in the manner described below. In order for the firing of the nerve cells in the environment of the respective stimulation contact surface to be triggered as efficiently as possible, but nevertheless safely, ie without tissue damage, short pulse trains (instead of long individual stimuli) are used. These pulse trains consist of 1 to 20, preferably 2 to 10, electrical charge balanced single pulses. By way of example, such a pulse train 110, which consists of three individual pulses 111, shown in Fig. 6. The individual pulses 111 are repeated at a frequency f above 100 Hz. The individual pulses 111 are current pulses which originate from an initial one

Pulse portion 112 and an adjoining, flowing in the opposite direction pulse component 113 composed. The duration 114 of the pulse component 112 is in the range between 40 μs and 400 μs, in particular in the range between 60 μs and 120 μs and in particular between 60 μs and 100 μs. The amplitude 115 of the pulse portion 112 is in the range between 0 mA and 10 mA, in particular between 2 inA and 5 mA. The amplitude of the pulse component 113 is less than the amplitude 115 of the pulse component 112. For this, the duration of the pulse component 113 is longer than that of the pulse component 112. The pulse components 112 and

113 are ideally dimensioned such that the charge transferred through them is the same for both pulse components, i. the areas hatched in FIG. 6 are the same size. As a result, by a single pulse 111 as much charge is introduced into the brain tissue, as is taken from the brain tissue.

The rectangular shape of the individual pulses 111 shown in FIG. 6 represents an ideal shape. Depending on the quality of the electronics generating the individual pulses 111, the ideal rectangular shape is deviated from.

The pulse trains are applied via the individual stimulation contact surfaces in such a way that the time difference between successive irritations (at different contact points) within a sequence of irritations is as large as possible, and in particular irritations at different points of contact. be avoided. This can be realized in the following ways:

a) The time difference between each two consecutive irritations by pulse trains (at different contact points) is constant. A complete sequence is understood as a sequence of irritations in which all contact points are successively stimulated by a pulse train. An incomplete sequence is understood to be a sequence of irritations, in which not all contact points with one another are successively selected

Pulse train be irritated; So it is at least one contact point recessed. A redundant sequence is understood as a sequence of irritations with pulse trains, in which at least one contact point is stimulated at least twice (but not one behind the other) within a sequence.

A sequence of pulse trains may in the simplest case be administered periodically, e.g. with a frequency in the range of the pathological frequency, with which the neurons fire synchronously in certain areas of the brain, or in the range of an integer multiple of the pathological frequency. The sequence can be clocked so that the sequence of irritations by means of pulse trains over time covers a mean period of the pathological activity. During the periodic administration of a sequence, the order of activation of the individual contact points should be varied from one sequence to the next in order to achieve as pronounced an effect as possible. In Fig. 7 this is exemplified. For ten stimulation contact areas, between times ti and tio a first

Sequence 120, the order of the stimulation pads 5- 1-10-8-6-2-9-4-3-7 selected and in a second sequence 121, the order 2-6-5-7-10-4-1-3- 9-8. For example, between two sequences, pauses of the length of one or up to 10 sequences can be maintained. Each of the sequences of pulse trains can be applied, for example, during the mean period of the pathological frequency f _PF , ie successive pulse train sequences are applied at a frequency in the range of the pathological frequency f _PF . If N contact surfaces are controlled within a pulse train sequence, pulse sequences which follow each other directly in time are applied at a frequency in the range of N * f _PF . Instead of the pathological frequency f _PF , even small integer multiples, eg double, triple or quadruple, of the pathological frequency f _PF can be selected. The pathological frequency in Parkinson's disease is about 5 Hz (or in the range of 4.5 Hz to 5.5 Hz). In Parkinson's patients with akinesia, the pathological frequency f _{PF is} in the range of 10 Hz to 30 Hz.

For even greater impact, complete, incomplete, and redundant sequences, each with varying order of stimulation pads, can be administered. In order to reduce the required stimulation current even further, pauses can be interposed during the consecutive administration of complete, incomplete and redundant sequences, each with a varying order of the stimulation contact surfaces, the durations of which amount to an integer multiple, but not more than ten times the duration of a sequence.

b) Instead of a constant time difference between successive irritations with pulse trains (at different contact points), uncorrelated random processes are used to control the pulse train irritations at the different contact points, allowing only random events in which the time differences of successive pulse train stimuli can be set as a parameter Do not fall below minimum value of eg 20 ms. Incident events which fall below this minimum value are recognized by the generator unit and not as triggers used for irritation.

c) The stimulation takes place as under b), only chaotic processes are used instead of random processes.

d) In a less preferred variant, pulse trains with a frequency f greater than 50 Hz and preferably greater than 100 Hz are permanently applied via a subset of the stimulation contact surfaces.

FIGS. 8 and 9 show two circuits 130 and 150 as possible implementations of the implant according to the invention. The circuit 130 shown in Fig. 8 is designed as a pure receiving system. The input of the circuit 130 forms a coil 131, in the vicinity of which the coil of the control device located outside the body is located during the operation of the implant. The two coils act as a transformer, by means of which high-frequency signals and electrical power are transmitted from the control device to the coil 131 by induction. The coil 131 can optionally be followed by a step-up transformer 132. The power absorbed by the coil 131 is supplied via an acting as a rectifier diode 133 of an energy storage unit 134 and stored there. The energy storage unit 134 can be realized, for example, as a charging capacitor with a high capacity or as a rechargeable Akkumu ^¬ lator. The voltage provided by the energy storage unit 134 is tapped by a voltage control circuit 135, which regulates this unregulated voltage to a supply voltage value required for the operation of the circuit 130. In particular, an integrated circuit 136 is operated with the supply voltage, into which - as can be seen from FIG. 8 - a large part of the components of the circuit 130 is integrated. Alternatively, the devices could be distributed to multiple integrated circuits. The high frequency signals received by the coil 131 containing the transmitted information are further processed by devices on the integrated circuit 136. For this purpose, the output of the warm-up transformer 132 is connected via a coupling capacitor 137 to an input of a demodulator 138. The demodulator 138 is for retrieving the information previously modulated in the controller to a carrier frequency. In demodulation, the information-carrying parameter (s), eg the frequency, phase, amplitude or the duty factor, of the modulated carrier are evaluated. The demodulated data are fed to a clock-and-data recovery unit 139, which imposes a reference clock generated in the integrated circuit 136 on the demodulated data. In a decoder 140, the data is subsequently decoded so that the output of the decoder 140 contains the control data provided by the control device for controlling the implant. The control data can be temporarily stored in a RAM (Random Access Memory) 141 and read from there by a generator 142. The generator 142 generates the pulse trains applied from the stimulation pads to the brain tissue. For example, the generator 142 may have access to certain basic forms of pulse trains, which are also stored in the RAM 141, for example. In this case, those of the

Control device transmitted control data only contain parameters on the basis of which the final configuration of the pulse trains generated by the generator 142 can be read. For example, these parameters relate to the amplitude, duration and frequency of the pulse trains as well as the order in which the pulse trains are applied via the individual stimulation contact surfaces.

From the generator 142, the pulse trains are each fed into a particular channel of a plurality of channels CHi to CH _n , which in turn are each in communication with one of the Stimulationskontaktflachen. Before the actual For stimulation, the digital data output by the generator 142 is converted into analog voltage values in digital-to-analog converters 143 and then converted into stimulation currents by means of voltage-to-current converters 144. From the outputs of the voltage-current converter 144, a feedback path 145 serving to control the level in each case leads to a summation point 146, which is connected in front of the associated digital / analog converter 143. Furthermore, in each case a capacitor 147 is connected between the outputs of the voltage-current converter 144 and the associated stimulation contact surfaces. The capacitors 147 connected in the signal paths of the stimulation signals prevents inadvertent transfer of too much charge to the patient's brain tissue.

The circuit 150 shown in FIG. 9 largely corresponds to the circuit 130 shown in FIG. 8. Identical components are therefore provided with the same reference numerals. In contrast to the circuit 130, measuring signals can be picked up by the circuit 150 via the stimulation contact surfaces and transmitted to the control device. For this purpose, each of the channels CHi to CH _{n is} connected to a filter 151 and a downstream analog-to-digital converter 152. The measurement signals digitized by the analog / digital converters 152 are fed to a unit 153 for data reduction and protocol generation and subsequently to a modulator 154. The modulator 154 controls a transistor 155, which is connected with its drain-source path in a resonant circuit formed by a resistor 156 and the transformer 132, via its gate electrode. By means of this driving of the transistor 155, the modulator 154 can modulate the signals generated by the resonant circuit before they are transmitted via the coil 131 to the control device.

In circuits 130 and 150, transformers are used for wireless transmission of signals. However, the invention is not limited to such transformers as transmitters. and receiving systems limited. Other types of transmitters and receivers may be used for wireless communication between the controller and the implant.

Claims

claims

An implant (10; 50; 80) comprising:

a receiving unit (11; 51; 81) for wirelessly receiving control signals,

a generator unit (12; 52; 82) connected to the receiving unit (11; 51; 81) for generating stimulation signals on the basis of the control signals, and

a stimulation unit (13; 53; 83) connected to the generator unit (12; 52; 82) for stimulating nerve cells with the stimulation signals.

The implant (50; 80) of claim 1, wherein the implant (50; 80) further comprises a measuring unit (53; 83) for receiving measuring signals from nerve cells and one with the measuring unit

(53; 83) connected to transmitting unit (51; 81) for wireless transmission of the measurement signals.

The implant (10; 50; 80) according to claim 1 or 2, wherein the implant (10; 50; 80) further comprises one with the receiving unit

(11; 51; 81), wherein the receiving unit (11; 51; 81) is adapted to wirelessly receive energy stored in the energy storage unit (134).

The implant (10; 50; 80) of claim 3, wherein the energy storage unit (134) is configured to provide a supply voltage for powering devices of the implant (10; 50; 80).

The implant (10; 50; 80) of any one of the preceding claims, wherein the nerve cells are brain cells.

6. Implant (10; 50; 80) according to one of the preceding claims, wherein the stimulation unit (13; 53; 83) has a

Plurality of stimulation pads (102) adapted to be in contact with the nerve cells. and to transmit the stimulation signals to the nerve cells.

7. The implant (10; 50; 80) according to claim 6, wherein the stimulation contact surfaces (102) are arranged on at least one electrode shaft (101).

The implant (10; 50; 80) of claim 6 or 7, wherein the generator unit (12; 52; 82) has a plurality of outputs respectively connected to one of the stimulation pads (102) and to which the stimulation signals are applied Pulse trains (110) are output.

The implant (10; 50; 80) according to claim 8, wherein the pulse trains (110) are each composed of individual pulses (111) and the individual pulses (111) are repeated at a frequency (f) greater than 100 Hz.

The implant (10; 50; 80) of claim 8 or 9, wherein the pulse trains (110) are output at the outputs at a time lag.

The implant (10; 50; 80) of claim 10, wherein the time interval between two consecutive pulse trains (110) is predetermined or varies statistically.

The implant (10; 50; 80) of claim 11, wherein a first order (120) of the outputs at which the pulse trains (110) are successively output is predetermined.

The implant (10; 50; 80) according to claim 12, wherein a second order (121) of the outputs at which the pulse trains (110) are successively output is given and the second order (121) after the first sequence (120 ).

The implant (10; 50; 80) of claim 13, wherein a pacing pause is maintained between passing through the first order (120) and passing through the second order (121).

The implant (10; 50; 80) of any one of claims 8 to 14, wherein the pulse trains (110) are each composed of current pulses.

The implant (10; 50; 80) of claim 15, wherein a respective capacitor (147) is connected between the outputs and the associated stimulation pads (102).

17. The implant (10; 50; 80) according to claim 8, wherein the control signals comprise parameters and the generator unit (12; 52; 82) is configured to use the parameters and based on predetermined basic pulse shapes to form the pulse trains (110). to generate.

18. stimulation system (20; 40; 70) comprising:

a control device (30; 60; 90) which

a first generator unit (31; 61; 91) for generating control signals, and

a first transmission unit (32; 62; 92) connected to the first generator unit (31; 61; 91) for wireless operation

Includes sending the control signals, and

an implant (10; 50; 80) which

a first receiving unit (11; 51; 81) for receiving the control signals wirelessly,

a second generator unit (12; 52; 82) connected to the first receiving unit (11; 51; 81) for generating stimulation signals based on the control signals, and a stimulation unit (13; 53, 83) for stimulating nerve cells with the stimulation signals covers asst.

19. A stimulation system (40; 70) according to claim 18, wherein the implant (50; 80) comprises a measuring unit (53; 83) for recording measurement signals from nerve cells and a second transmission unit (51; 81) connected to the measuring unit (53; ) for wirelessly transmitting the measurement signals, and wherein the control device (60; 90) comprises a second receiving unit (62; 92) for wirelessly receiving the measurement signals.

The stimulation system (20; 40; 70) of claim 18 or 19, wherein the implant (10; 50; 80) comprises an energy storage unit (134) connected to the first receiving unit (11; 51; 81), and wherein the first transmitting unit (10; 32; 62; 92) and the first receiving unit (11; 51; 81) are adapted to wirelessly transmit energy stored in the energy storage unit (134).

The pacing system (20; 40; 70) of any one of claims 18 to 20, wherein the controller (30; 60; 90) is adapted to be located outside of the body.

22. Method with the following steps:

- generating control signals; - wireless transmission of the control signals;

- wireless receiving the control signals;

Generating stimulation signals based on the received control signals; and

- Stimulate nerve cells with the stimulation signals.

23. The method of claim 22, wherein measurement signals are received by the nerve cells and the measurement signals are sent wirelessly.

24. The method of claim 22 or 23, wherein the nerve cells are brain cells.

The method of any one of claims 22 to 24, wherein the stimulation signals are pulse trains (110).

26. The method of claim 25, wherein the pulse trains (110) are each composed of individual pulses (111) and the

Single pulses (111) are repeated with a frequency (f) greater than 100 Hz.

27. The method according to claim 25 or 26, wherein the pulse trains (110) are applied with a time delay at different locations on the nerve cells.

28. The method of claim 27, wherein the time interval between two consecutive pulse trains (110) is predetermined or is varied statistically.

29. The method of claim 25, wherein the pulse trains are each composed of current pulses.