DE2660864C1 - Device for stimulating muscles for the treatment of spinal curvature - Google Patents

Description

- A switch-off period transmitter (64, 68), which has a sequence of counting pulses with a first A predetermined frequency generating first astable multivibrator (64) and a the counting pulses responsive first counter (68), after counting a first predetermined Number of counting pulses generates an output signal;

- A switch-on period encoder (70, 72), the one a sequence of counting pulses with a second astable multivibrator (70) generating a second predetermined frequency and a on the counting pulses responsive second counter (72) after counting a generating a reset signal for a second predetermined number of counting pulses;

- A first device (69) which, in response to the output signal, the first astable multivibrator (64) locks and unlocks the wide astable multivibrator (70);

- A second device (83 to 86) which, on the output signal, the pulse generator to a electrical energy source (50) connects to during the counting period of the switch-on period encoder (70,72) generate stimulus pulses; as

- means (76, 77) responsive to the reset signal for resetting the first Counter (68) for the purpose of terminating the output signal and interrupting the generation of stimulus pulses during the counting period of the switch-off period transmitter (64,68).

2. Apparatus according to claim 1, characterized in that the switch-on period between 1 and 5 seconds and the switch-off period between 5 and 25 seconds can be set.

3. Apparatus according to claim 1 or 2, characterized by one of the switch-off period generator (64,68) connected device (65,66, 67) for setting the switch-off period.

4. Apparatus according to claim 3, characterized in that the switch-off period adjusting device (65,66,67) one with the first astable multivibrator (64) associated arrangement for controlling the oscillation frequency of the first astable multivibrator having.

5. Apparatus according to claim 4, characterized in that the frequency control device of the first astable multivibrators (64) an adjustable

ÄC timer (65,66,67)

6. Device according to one of the preceding claims, characterized by one of the switch-on period encoder (70, 72) connected device (73,74,75) for setting the switch-on period.

7. Apparatus according to claim 6, characterized in that the switch-on period adjusting device (73, 74, 75) an arrangement connected to the second astable multivibrator (70) for controlling the Has oscillation frequency of the second astable multivibrator.

8. Apparatus according to claim 7, characterized in that the frequency control device of the second astable multivibrator (70) has an adjustable ÄC time element (73,74,75)

9. Device according to one of the preceding claims, characterized by one between the electrical energy source (50) and the cyclic clock generator (53) lying switching device (51), after the actuation of which passes electrical energy from the energy source (50) to the clock generator, and a with the two counters (68, 72) coupled resetting device (79 to 82), which when the Switching device (51) resets the two counters (68, 72)

The invention relates to a device for stimulating muscles for the treatment of spinal curvatures, with electrodes designed to transmit electrical stimulation impulses to the muscles and a pulse generator in communication with the electrodes, which is activated during respective switch-on-switch-off cycles provides muscle contraction and relaxation.

A device of this type is from CA magazine "The Medical Post", Volume 11, No. 6 (March 1975), pages 34 and 35, known. More details regarding the design of the device are given there not specified.

Furthermore, a circuit arrangement for providing stimulation pulses suitable for muscle stimulation is known (DE-AS 15 64 329), which are formed into pulse packets with intermediate relaxation pauses. The on-off durations of /? C members, each amounting to 750 ms, for example, are determined. The longer these time intervals have to be dimensioned, the larger capacitors are required. The arrangement becomes accordingly bulky and expensive.
The invention is based on the object of specifying a device which is relatively inexpensive to set up and which takes up relatively little space and with which switch-on and switch-off cycles of practically any duration can be reliably and precisely specified on a long-term basis.

This object is achieved according to the invention in that a switch-on-switch-off cycles determining cyclic clock with a switch-on period and a switch-off period as well as an oscillator available which generates the stimulus pulses in response to the switch-on period of the clock, and that the clock is provided with

- a switch-off period transmitter, which has a foI

ge of counting pulses with a first predetermined frequency generating first astable multivibrator and a first counter responsive to the counting pulses, which after counting a first predetermined number of counting pulses generates an output signal;

- a switch-on period encoder, de / one a sequence of counting pulses with a second predetermined frequency generating second astable Having a multivibrator and a second counter responsive to the counting pulses, which after Counting a second predetermined number of counting pulses generating a reset signal;

- A first device which blocks the first astable multivibrator in response to the output signal and unlocks the second astable multivibrator;

- A second device which, in response to the output signal, connects the pulse generator to an electrical Energy source connected to generate stimulus pulses during the counting period of the switch-on period transmitter; as

A device, responsive to the reset signal, for resetting the first counter for the purpose of terminating the output signal and interrupting the generation of stimulus pulses during the counting time of the switch-off period transmitter.

In the device according to the invention, long switch-on and switch-off periods can also be provided, without the need for voluminous and expensive capacitors. Multivibrators and counters are available available in a compact design at low cost.

Advantageous further refinements of the invention emerge from the subclaims.

The invention is explained in more detail below on the basis of a preferred exemplary embodiment. In the Drawings shows

F i g. 1 is a schematic representation of a typical scoliotic curvature of the spine and a electrospinal stimulation device according to the invention, as well as

F i g. 2 and 3 are schematic circuit diagrams of the electronic transmitting and receiving parts of the electrospinal Stimulator.

In Fig. 1 is a schematic representation of a spine with a typical scoliotic curvature, which by means of an electrospinal stimulation current device is to be treated. The curve consists of a chest curve 10, which is bounded by vertebrae U and 12, and one bounded by vertebrae 12 and 14 Lumbar curvature 13. It will be understood that the curvature delimiting vertebrae are about everyone any vertebra of the spine can act. The vortex 11 is the highest vortex, its upper edge is inclined with respect to the thoracic space, while the vertebra 14 is the deepest vertebra, its lower edge has an inclination towards the lumbar space. The vertebra 12 is the deepest vertebra, its lower edge The highest is inclined in relation to the thoracic space Vertebra, the upper edge of which is inclined with respect to the lumbar space. At the illustrated spine Both the thoracic curvature and the lumbar curvature are approximately 65 ° when the measurement takes place according to the known Cobb method.

A typical scoliosis curve consists of a main curve and one or more secondary curves, which represent a compensation mechanism to the head immediately above the pelvis to keep. During the treatment, the main curve is stretched by an electrically triggered one Contraction of the paraspinal muscles near the convex sides of the main curvature without causing it to a contraction of the paraspinal muscles that extend so far beyond the main curvature that their contraction would worsen the compensatory curvature. In the case of the in FIG. 1 illustrated Curvature does this by placing helical stimulus electrodes 40 within the deeper ones paraspinal muscles on the convex side of the curve (at curve 10 on the right side) to be ordered.

By means of the stimulation current device according to FIG. 1, the paraspinal muscles are trained in that they are strengthened by applying electrical stimulation pulses B to three stimulation electrodes 40. At least two of the stimulation electrodes 40 are active electrodes, while one of the stimulation electrodes is an indifferent electrode. The stimulation electrodes 40 are introduced into the paraspinal muscles adjacent to the main curve 10 of the spine at different depths. It is believed that the application of electrical stimuli will hypertrophy these muscles, causing a slight imbalance compared to the muscles on the concave side of the curve * 0 as the child grows in the following years. This muscle imbalance brings the convexity of the spine 10 to a standstill or corrects it.

The stimulation electrodes 40 are connected to lines 48 which are connected to a biocompatible, electronic RF signal receiver 17 which is implanted under the main body. Following the introduction of the stimulation electrodes 40, the receiver 17 is arranged subcutaneously by a surgical procedure. When using the electrical stimulation device, the patient places a transmitting antenna 18 over the point at which the receiver 17 is implanted. The antenna 18 is connected via a line 19 to the output of an RF transmitter 24 which generates a pulse A.

In operation, the RF transmitter 24 is brought into close proximity to the body of the patient at rest. The antenna 18 is held above the antenna of the receiver 1 / by means of an adhesive plaster. The patient then turns on the transmitter. The transmitter 24 generates a series of stimulus pulses A cyclically. The pulses are picked up by the receiver 17 and fed to the stimulus electrodes 40 in the form of the stimulus pulses B. Each of the pulses A and B has a preset width and amplitude. The impulses repeat themselves with a preselected frequency. The muscles can recover during the switch-off period. The on and off periods can be 1 to 5 s and 5 to 25 s, respectively, so that the stimulated muscles can contract and relax without causing fatigue. The pulse repetition rate can be 30 to 50 pulses per second. The amplitude of the impulses can be set between 0 and 10 V on the stimulation electrodes. The pulse width is expediently about 220 μ $. The parameters can be changed postoperatively while the patient's progress is monitored.

In the F i g. 2 and 3, a circuit arrangement of the transmitter and the receiver of the electrospinal stimulation device is illustrated in detail. Via its antenna 18, the transmitter 24 cyclically emits a sequence of RF stimulus pulses with a predetermined repetition rate.

frequency, pulse width and amplitude. These big ones can be adjusted. The rest is through further actuators the circuit arrangement also allows the duration of the pulse trains to be set. The transmitter has a power source for example in the form of a 9 V battery 50. The battery 50 can be conventional Acting dry cell that feeds the transmitter and, if necessary, exchanged by the patient can be. An on-off switch 51 is in series with the battery and the input 52 of a clock 53, its structure in detail with reference to FIGS. 2 is explained. The clock generator 53 has a cyclic clock unit for specifying switch-on and switch-off periods, which are individually between a Set the millisecond and one hour. The clock generator can be designed so that the duty cycle between one and five seconds and the switch-off time between five and 25 seconds is. While the clock generator 53 is switched on, a supply voltage is applied from the output 54 to the pulse repetition frequency determining oscillator 55 placed. Whenever the switch 51 is closed, the supply voltage is applied via line 56 to pulse width control circuit 58 and RF oscillator 60. None However, this assembly works as long as the oscillator 55 is not supplied with voltage. A filter capacitor 61 lies between input 52 and ground.

The oscillator 55 generates a sequence of pulses which are repeated at a predetermined repetition frequency as long as the supply voltage is applied to the output 54 of the clock generator 53. This pulse train is fed to the pulse width control circuit 58. The pulse width control circuit 58 can comprise a monostable multivibrator which is triggered by each pulse emitted by the oscillator 55 in order to generate a further pulse. The multivibrator is equipped with a control resistor to adjust the width of the emitted pulse. The RF oscillator 60 oscillates at a predetermined frequency, for example 460 kHz, when an output pulse from the pulse width control circuit 58 is received repeat the preset repetition rate. Each pulse accordingly consists of an H F burst of energy, as shown in FIG. 1 is indicated at A. The RF oscillator 60 has an amplitude control circuit in order to be able to set the voltage amplitude of the RF pulses.

The antenna 18 is connected to the output of the RF oscillator 60. Your job is. the RF pulses to get through the skin of the patient to the receiver circuit. The energy arrives from the transmitting antenna to an antenna 62 located in the receiver 17, where it is received and via the Leads 48 and the electrodes 40 is fed to the muscle.

The current source 50 is connected in series with the input 52 via the switch 51. As can be seen from FIG. 66 and 67 is determined. A first binary counter 68 receives the pulses from the first astable multivibrator 64 until a predetermined count is reached. The counter 68 then gives a high output signal on a line 69. This signal is fed to the Α input of the multivibrator 64 to stop it. Furthermore, the signal arrives at the / t input of a second astable multivibrator 70. Due to the high level signal at input A of the multivibrator 70, it sends pulses to a second binary counter 72, which counts the number of pulses delivered by the second astable multivibrator 70, until a predetermined count is reached. The frequency of the pulses generated by the second astable multivibrator 70 is determined by an λC time element 73, 74 and 75.

When the second counter 72 has reached the full count, a line 76 is high Output signal which is fed to the reset input of the first counter 68 via a diode 77; through this the high output on line 69 disappears. At this point, the low output causes the / 4 input of the first astable multivibrator 64 approaches that this multivibrator begins to oscillate. The low-lying output signal, that appears at the / 4 input of the second astable multivibrator 70, has the consequence that this Multivibrator stops vibrating. The output signal generated by the first astable multivibrator 64 is fed via a line 78 to the reset input of the counter 72; the high output signal disappears on line 76; the counter 68 is no longer reset and can count kick off.

The oscillation frequencies of the astable multivibrators 64 and 70 are determined by the charging time of the capacitors 67 and 75 determined; they can be changed by adjusting the variable resistors 66 and 74, respectively.

In order to ensure that the clock generator 53 functions properly, one of a capacitor 79 is used. a resistor 80 and diodes 81 and 82 and formed between the voltage supply input 52 as well as the reset inputs of the counters 68 and 72 lying reset circuit for the fact that when applying Voltage due to the patient closing switch 51 (Fig. 3) shows the counters in both Counters can be reset to zero by supplying voltage across the capacitor 79 and the diodes 81, 82 is performed. Since the supply voltage on the capacitor 79 rises rapidly, the reset signal disappears fast; the counters are made functional in the manner explained; the clock 53 is at the beginning its switch-on period.

Supply voltage is fed to the oscillator 55 during the switch-on period of the clock generator 53, i. H. for the Period of time following the reaching of the full count value in the first counter 68 and during which the second counter 72 counts The high or relatively positive output signal of the first counter 68 is over the line 69 is fed to the base of a switching transistor 83, the emitter-collector path of which is between ground and the connection point of resistors 84 and 85 is. Resistor 84 is connected to the supply voltage source connected, while the resistor 85 is connected to the base of a power switching transistor 86 The positive voltage applied to the base of transistor 83 turns transistor 83 on; the The voltage at the base of the transistor 86 drops so that the transistor 86 is also energized and battery current from input 52 to output 54 allows battery voltage to flow across the transistor 86 is applied to the oscillator 55

The astable multivibrators and the counters can expediently be integrated C-MOS circuits of the type RCA-4047 and RCA-4040, the

marketed by RCA Corporation.

The oscillator 55 of FIG. 3 has a reference voltage source, to which a transistor 88, resistors 90, 91, 92 and 93, a capacitor 94 and a diode 95 belong and which applies a reference voltage to the oscillator part of component 55, which is provided by a programmable uni-function transistor (PUT) 96 , a frequency variable resistor 97, a resistor 98 and a capacitor 99 is formed. The supply voltage appears at a reference voltage divider formed by resistors 90 and 91; the junction of the two resistors 90, 91 is connected to the base of transistor 88. The transistor 88 is thereby normally biased so that it allows the supply voltage minus the forward voltage drop of the transistor 88 to appear at the junction of the resistor 92 and the capacitor 94. The supply voltage applied in this way via the resistors 92, 93 and the diode 95 is fed to the G-PoI of the unijunction transistor 96 in order to serve there as a reference voltage level. The resistors 92 and 93 have a relatively low and a relatively high resistance value, respectively. As a result, the capacitor 94, the resistor 92 and the diode 95 form a low-resistance voltage source for the G-PoI of the unijunction transistor 96 in the forward direction 93 at the G-PoI represents a high impedance. The frequency of the pulse generation is determined by the RC toe member which includes the frequency variable resistor 97, the resistor 98, the capacitor 99 and the unijunction transistor 96. When the supply voltage is applied to the λC timer, the voltage on the capacitor 99 rises until the voltage appearing at the anode of the unijunction transistor 96 exceeds the reference voltage at the G-PoI, whereupon the unijunction transistor 96 is made conductive to produce an output pulse at its cathode submit. When the unijunction transistor conducts, the voltage present at the capacitor 99 is only discharged via resistors 100 and 102 to the reference potential at the G-PoI. The unijunction transistor% is made conductive as long as the positive voltage applied to its anode exceeds the voltage applied to the G-PoI. The values of the capacitor 99 and the resistors 100 and 102 are selected in such a way that a positive needle-shaped output signal is produced which is sent via a line 103 to the pulse width control circuit 58.

f λ r \ : ιι_ i__u cc ι j: * j: ~

guiigau cijucui. uci v * r:> £ .iimiui summing jj uiiu uatini uic The frequency with which stimulus pulses are generated can be preselected by changing the frequency variable resistor 97.

The pulse width control circuit 58 operates as a monostable multivibrator which, in response to the positive needle-shaped output signal of the oscillator circuit 55, generates an output pulse with a uniform pulse width which is fed to the input of the RF oscillator 60.

Since the cathode of the unijunction transistor 96 is normally held at ground potential via the resistors 100 and 102 , a transistor 104 connected downstream normally does not carry any current. The pulse width determining elements of the pulse width control circuit 58 include a pulse width variable resistor 106, a resistor 108, a capacitor 110 and a resistor 112. The junction of resistor 112 and capacitor 110 is connected to the collector of the normally off transistor 104 , while capacitor 1 10 normally charges to a predetermined voltage of positive polarity at the connection point mentioned. The base of a second transistor 114 is connected to the junction of resistor 108 and capacitor 110 . The collector-emitter path of the

ίο transistor 114 is in series with a resistor 116 parallel to the supply voltage source. The junction of the resistor 116 and the collector of the transistor 114 is connected to the junction of the resistors 100 and 102 via a line 118 .

Normally, transistor 114 conducts when it is off

τ *: _a * ι \ λ Ct _ -.-. jn «... j .... ι _A :« .. _H _ 4 4 ο & i. «.

iiauaiaivii iv * juuiu, au uau an uct i-ictLuiig ι io maascpotential lies

When a needle-shaped signal generated at the cathode of the Unijunctionstransistors 96 is applied via line 103 to the base of the transistor 104, the transistor 104 is energized. The capacitor 110 discharges via the transistor 104 and the resistors 106 and 108. At the same time, the transistor 114 is blocked, so that the potential on the line 118 rises. The increased potential on line 118 passes through resistor 100 and line 103 back to the base of transistor 104, which means that it is kept live by positive feedback as long as capacitor 110 continues to discharge. This period of time forms the pulse width of the transmitted stimulus pulses. The output pulses from the pulse width control circuit 58 are a square wave that appears on a line 119.
The line 119 is connected to the input of the RF oscillator 60 . The output pulse running over the line 119 triggers the oscillator 60 so that it generates an RF transmission signal with a pulse width that can be determined by the circuit 58 and a repetition frequency predetermined by the circuit 55 while the clock generator 53 is switched on. The amplitude of the transmitted RF stimulus signal can be adjusted by means of an amplitude control element of the oscillator 60 .

The RF oscillator 60 includes:

1. a Colpitts oscillator with transistors 120 and 122, an adjustable inductance 124, capacitors 126 and 128 and a resistor 130 which generates an oscillator signal of a predetermined frequency, for example 46OkHz, during the duration of the output pulse of the circuit stage 55; a relay amplifier responsive to the RF signal and having a transistor 131, resistors 132, 134 and 136 and a capacitor 138 for coupling the RF signal to;

3. a C amplifier with a transistor 140, an inductance 142, an amplitude variable resistor 144 and a resistor 146 for further amplifying and separating the HF signal from the DC supply voltage, and;

4. An oscillator antenna circuit with capacitors 148 and 150 which, in conjunction with the inductance of the antenna 18 , resonates with the same RF frequency, for example 460 kHz.

The inductive and capacitive values of the Colpitts oscillator circuit are dimensioned in such a way that when coupled to the supply voltage by current conduction

9

of transistors 120 and 122 due to the positive output pulse on line 119 at the base of transistor 131, an HF oscillation occurs. The transistors 131 and 140 amplify the oscillations and

couple it to the resonance antenna circuit. The inductor 142 forms a low impedance path

for high-frequency signals and a high-impedance path for the DC supply voltage potential, so that

the transistor 140 can operate as a C amplifier. Of the

Current amplification factor of transistor 140 is by means of

of the variable resistor 144 adjustable. This adjustment is usually made by the surgeon at the time of implantation and during postoperative treatment.

The RF signals are picked up by the receiver 17, which is tuned to resonance. The recipient

17 comprises the inductance 62 of the receiving antenna, capacitors 154, 156 and 158, a diode 160 and a resistor 162, all of which are connected in a known manner as receivers in order to acquire 460 kHz signals, rectify the acquired signals and filter out the signals, a pulse train of the in F i g. 1 type illustrated at B. The lines 48, which forward the received RF stimulus signals to the remote stimulation sites, are connected to the receiver 17 in the manner illustrated.

The device according to the invention can operate in an advantageous manner with three electrodes, namely two negative stimulus electrodes and one positive indifferent electrode. With the stimulus signals it can be are intermittent bursts of two-phase square wave pulses, with the stimulation for a Duration of 1 to 5 seconds each with intervals of 5 to 25 seconds in between. Such intermittent stimulation prevents muscle fatigue. A duty cycle (Ratio of on-time to off-time) of 1 to 5 proved to be beneficial to muscle fatigue further decrease. Advantageously, will

J with a pulse repetition rate of 30 to 60 pulses each

, a second and with a pulse amplitude of approximately

3 V worked. Stimulation expediently takes place within a period of time during the treatment from 8 to 10 hours during sleep; treatment continues until the patient has at least the Achieved maturity, generally until the patient is 16 to

18 years of age However, when the desired correction is approached, treatment can be on an intermittent (not daily) basis

leads to the risk of overcorrection too

Reduce.

For this purpose 2 sheets of drawings

S5

• 0

CS

Claims (1)

Patent claims: 1. Device for stimulating muscles for the treatment of spinal curvatures, with electrodes designed to transmit electrical stimulation impulses to the muscles and a pulse generator connected to the electrodes, which during the relevant switch-on-switch-off cycles ensures muscle contraction and relaxation, thereby marked e t that a switch-on-switch-off cycles determining cyclic clock (53) with a switch-on period and a switch-off period as well as an oscillator (55) are present, which is based on the switch-on period of the clock (53) responsively generated the stimulus pulses, and that the clock (S3) provided is with