Diagnostic Apparatus For Automatically Generating An Intensity-time Diagram Showing Points Of Minimum Involuntary Muscle Movement

Abstract

Both amplitude and pulse width of pulses applied to the muscle are varied automatically, a given number of pulses being applied at a given amplitude and pulse width prior to increasing the amplitude. The given number varies with the pulse width. The amplitude is increased until involuntary muscle movement results. The same procedure is repeated at the subsequent pulse width.

Description

BACKGROUND OF THE INVENTION:

This invention relates to a diagnostic apparatus for generating an intensity-time diagram showing points of minimum involuntary muscle movement as a function of amplitude and duration of electrical pulses applied to said muscle.

It is known that when electrical pulses are applied to the muscles in a human body, and in particular when these pulses are current pulses, then a healthy muscle will respond to pulses having amplitudes larger than a given amplitude at a given pulse width by contracting. However, muscles injured by sickness contract at different values from those causing contraction in healthy muscles. Thus in order to diagnose illnesses certain intensity-time diagrams are recorded showing characteristic values at which the muscles contract. These diagrams give a good indication of the condition of the muscles. It should be noted that for this discussion the term intensity will be taken to mean the amplitude of the pulse applied to the muscle, while the term time will refer to the pulse width of the pulse applied to the muscle.

Diagnostic apparatus of the above-described type is known wherein the adjustment of the pulse width takes place automatically while the amplitude of the pulses is set by hand. The point at which the muscle contraction occurs is then recorded by means of a two coordinate type recorder which is activated by means of a switch.

SUMMARY OF THE INVENTION

It is the object of the present invention to furnish diagnostic apparatus for generating an intensity-time diagram showing points of minimum involuntary muscle movement as a function of amplitude and duration of electrical pulses applied to said muscle, wherein the required amplitude adjustment as well as the duration adjustments are carried out automatically.

It is a further object of the present invention that apparatus of this type be combined with recording apparatus which is both accurate and simple.

It is a further object of the present invention to greatly decrease the time required to generate the above-mentioned intensity-time diagram.

The present invention comprises adjustable pulse generator means furnishing a sequence of electrical pulses, each of said pulses having a determined amplitude and pulse width. It further comprises first counter means connected to said pulse generator means for counting said electrical pulses and automatically changing the amplitude of said pulses following receipt of a given number of said pulses. Varying means vary said given number in dependence upon said pulse width of said pulses. Finally, stop means stop said first counting means upon appearance of said involuntary muscle movement.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 shows an intensity-time diagram;

FIG. 2 is a block diagram of the apparatus of the present invention required for determining the rheobase;

FIG. 3 is a block diagram of the portion of the apparatus required for determining the chronaxie;

FIG. 4 is a circuit diagram showing the control pulse generator;

FIG. 5 is a circuit diagram showing the amplitude control control means;

FIG. 6 is a circuit diagram showing the circuit means for changing the pulse width and pulse interval of the pulses furnished by the generator of FIG. 4;

FIG. 7 is a schematic diagram of the sensor means for sensing the muscle contractions;

FIG. 8 is a circuit diagram showing the recording arrangement; and

FIG. 9 shows the interconnection between counters 12, 16 and 17 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

A preferred embodiment of the present invention will now be described with reference to the drawing.

FIG. 1 shows an intensity-time diagram as is to be generated by the present invention. The pulse width of the applied pulses is plotted along the abscissa, while the ordinate represents the amplitude of the pulses in milliamps. Associated with each of the pulse widths shown along the abscissa is a determined pulse interval. Thus for pulses having a pulse width of one second, the interval between pulses is two seconds and, therefore, the width/interval ratio 0.5. For a pulse width of one second and an interval of 2 seconds, the current intensity is measured which is just barely sufficient to effect a minimum involuntary muscle movement, that is a contraction or twitching. The so-found valve is designated as the basic threshold or rheobase. It is designated by the letter A in FIG. 1. A second important point in the diagram is designated with reference letter B, which represents the chronaxie. For determining the chronaxie, the time interval is measured for which a current having twice the amplitude of the rheobase value must flow in order that the minimum involuntary muscle movement takes place (the time interval herein referred to is the pulse width of the applied pulses). A further value, designated by E in FIG. 1 is designated as use time and represents the pulse width required to cause a minimum involuntary muscle movement when the pulse amplitude is the same as that of the rheobase.

The points mentioned above, as well as the curves connecting said points, can of course be derived from pulses having different pulse shapes. The curve designated by C was derived using rectangular pulses, while the curve having reference numeral D indicates a curve derived using pulses having a logarithmic shape. These curves and the rheobase and chronaxie values can be used to drawn conclusions about the condition of the muscles of the patient.

In FIG. 2, an electrode 10 is connected to the patient in order that the diagram described in FIG. 1 may be generated. The electrode 10 is connected to a current source 11 which has associated amplitude control circuit means. The current source 11 and the amplitude control circuit means associated therewith are connected to the outputs y.sub.1 -y.sub.n of amplitude control counting means denoted by reference numeral 12. The amplitude of the current applied to the patient varies as a function of the count registered on the amplitude control counting means, that is on which the outputs y.sub.1 -y.sub.n is energized. Lamps 13 are connected, one to each output y.sub.1 -y.sub.n. These lamps thus indicate the count on counter 12 and thus the amplitude of the pulses applied to the patient. Each lamp lights when the output to which it is connected caries a "1" signal. The lamps 13 are also shown again as part of the means indicating the point in the intensity-time diagram, 28. They are mounted in a lamp bank 32.

The reverse counting input (R) of counter 12 is connected to the output of AND-gate means 14. The forward counting input (F) of counter 12 is connected to the output of control pulse counting means 17 whose input is connected to control pulse generator means 18 through additional AND-gate means 15. The second input of additional AND-gate means 15 is connected via an inverter 19 to the output of AND-gate 14, whereby control pulses generated by pulse generator 18 are transmitted to the counter 17 when the output signal of AND-gate 14 is a O signal. Under these conditions counter 17 counts the pulses generated by pulse generator 18. When the number of so-counted control pulses is equal to a given number, counter 17 furnishes a counter advance signal to amplitude control counting means 12, thereby advancing the count on counter 12 by one unit. This increases the amplitude of the pulses furnished by stage 11 to electrode 10. Further, it causes the next-following lamp 13 to light. The count of counter 17 at which the counter advance signal is furnished in turn depends upon the output of counter 16 herein referred to as timing counter means.

The control pulses furnished by the pulse generator 18 are also applied directly to stage 11. In this stage they operate switching means which cause the current pulses to be applied to electrode 10 with a frequency and a pulse width determined by the pulses furnished by pulse generator 18. The pulse width and the frequency of the pulses furnished by pulse generator 18 in turn depend upon the output of the timing counter means, namely counter 16.

The reset pulse counting means, namely a counter 20 have an input connected to the output of AND-gate 14. A predetermined reset counting output terminal is connected to one input of AND-gate 14, which causes AND-gate 14 to become conductive when counter 20 has reached a particular count. Further, the forward counting input of counter 16 is connected to the predetermined reset counting output terminal of counter 20 (designated 3 0 in FIG. 2) through an inverter 21. Thus as soon as a zero signal appears at the selected output of counter 20, counter 16 is advanced by one count. The second input of AND-gate 14 is connected to the output of second pulse generator means 22. Second pulse generator means 22 have an input connected to a switch 23, closing of which furnishes a reset signal starting said second pulse generator means. Power is supplied to the arrangement shown in FIG. 2 through a main switch which is not shown.

The first input of AND-gate 14 is also directly connected to the first input of a NAND-gate 24 to whose second input is applied one output of a bistable stage 25 which is shown in FIG. 3 and will be described in greater detail in connection with that Figure. The output of NAND-gate 24 is connected to the input of a second NAND-gate 26 to whose second input a phototransistor 27 is connected. This phototransistor is part of the fine positioning means for the table carrying the diagram and will be described in greater detail below. The output of second NAND-gate 26 is connected to the input of the control pulse generator 18. Pulse generator 18 is thus activated when the correct inputs are present for the NAND-gates 24 and 26.

Pulse generator 22, counter 17 and counter 20 are all connected to stop means, here a switch 29 which is closed by the operator of the apparatus when the minimum involuntary muscle movement is observed. Operation of switch 29 causes pulse generator 22 to be disconnected, and counters 17 and 20 to be deactivated and reset to zero. Alternatively (by switching a selector switch 29 from the position shown in FIG. 2 to a position connecting terminal b of said switch to the remainder of the circuit), the arrangement can be automated even further by substituting another embodiment of stop means, namely automatic sensor means 30 which, as will be described in more detail below, furnish a pulse upon occurrence of the muscle contraction. The pulse of course operates exactly as does the closing of switch 29, but the arrangement 30 does not require anyone to operate the equipment and observe the patient.

The above-described arrangement operates as follows:

To start the equipment, switch 23 is closed. This causes pulse generator 22 to start generating pulses. At this point counter 20 is in its null position which is so arranged that the predetermined reset counting output terminal carries a I signal. This I signal is applied to one input of AND-gate 14 and therefore allows this AND-gate to be conductive for pulses from the second pulse generator means. These pulses are therefore applied to the input of counter 20, where they continue to increase the count on said counter, one unit for each received pulse. The pulses appearing at the output of AND-gate 14 are also applied to the reverse counting input of counter 12, where they result in a reverse count of one unit for each received pulse. Thus counter 12 is reset, until, at the most, its zero position is reached.

For a predetermined count on counter 20, a O signal appears at the predetermined reset counting output terminal. This causes AND-gate 14 to be blocked so that no further inputs are received by counters 20 and 12. Further, the O signal at the predetermined reset counting output terminal of the reset pulse counting means 20 causes counter 16 to be moved to the x.sub.1 position.

The x.sub.1 output signal of counter 16 is used to move a table 31 which is part of the indicating means 28. The signal causes the table to be moved in a direction perpendicular to the axis of the lamp bank 32. This lamp bank, as previously explained, carries lamps 13. For greater clarity, lamps 13 are again shown in the lamp bank 32. Table 31 has a paper, recording means, which carry the diagram shown in FIG. 1. The paper is spread upon the table in such a way that each intersection of the vertical and horizontal lines is over a hole 33 in the table. Movement of the table in the direction indicated by the arrow in proportion to the signal x.sub.1 thus causes the x values to be generated, while the y value, that is the ordinate, is furnished by the lighting of one of the lamps 14. Thus when counter 16 is switched to furnish the x.sub.1 output signal, table 31 is driven by motor 34 into the position wherein the lamp bank is lined up with the x.sub.1 coordinate shown in FIG. 1. When the table has moved into the correct position the hole 35 shown in FIG. 2 is lined up with a light source 37 and a phototransistor 27 and phototransistor 27 thus furnishes a signal to the second input of NAND-gate 26 which causes this NAND-gate to become conductive for signals furnished by first NAND-gate 24. The signal from phototransistor 27 is also used to stop the motor, 34, which moves the table. This will be described in more detail below. When the zero signal next appears at the output of counter 20, the control pulse generator means 18 are thus activated. At this point, pulse generator 18 commences to furnish pulses having a pulse width and pulse intervals determined by the output of counter 16. To correspond with FIG. 1, the first pulse width would be one second, and the first pulse interval two seconds. At this time counter 12 furnishes a y.sub.1 output which controls the amplitude of the current to be a relatively small amplitude of, according to FIG. 1, 1 milliamper.

Current pulses are thus applied to electrode 10 having a pulse width and pulse interval determined by pulse generator 18 and an amplitude determined by counter 12. A number of identical pulses is applied to the patient in order that any muscle action may be observed before a higher amplitude current is used. The reaction time of the observer observing the patient, if such be present, must of course also be taken into consideration. Thus counter 17 counts the pulses furnished by pulse generator 18 and furnishes a counter advance signal to counter 12 only after a predetermined number of identical pulses has been applied to electrode 10 and thus to the muscle of the patient. Only when counter 17 has reached a predetermined counting output, which, in turn, is determined by the state of counter 16, and no muscle twitching has been observed, is a counter advance signal applied to counter 12, thereby increasing the amplitude of the current pulses applied to the patient. From FIG. 1 it is seen that when the counter 12 furnishes a count y.sub.2, the amplitude of the current in the pulses applied to the patient is 1.5 miliamps. Simultaneously with the furnishing of the counter advance signal to counter 12, counter 17 is reset. Further, the change in the count on counter 12 of course causes a different lamp 13 to light. Specifically of course the next lamp following the lamp activated by output y.sub.1 will light. Again a predetermined number of identical pulses is furnished until counter 17, in the absence of a muscle twitch, again advances counter 12. The amplitude of the current pulses applied to the muscle of the patient is increased until the minimum muscle movement is observed and the operator of the machine operates stop switch 29 or, alternatively, the automatic stop means 30 are activated by the twitching of the muscle. This causes pulse generator 22 to be deactivated and counters 17 and 20 to be deactivated and reset to zero. The place on the paper may now be marked under which the lamp 13 is lit. This first measured value which was obtained from pulses having a pulse width of one second and an interval of two seconds is, as mentioned above, designated the rheobase.

For generating the next pulse on the diagram switch 23 must again be activated. The previously reset counter 20 is furnished pulses through AND-gate 14 for a forward counting operation, while counter 12 is simultaneously reset an equal number of steps. Counter 12 may not be reset all the way to the value of y.sub.1 in order to speed the measuring process. The number of steps that counter 12 is reset is so chosen that one is absolutely certain that the minimum muscle twitching will be observed. Experience has shown that it is sufficient to reset counter 12 by approximately six steps, since this will result in a current pulse amplitude which does not as yet cause muscle twitching. Reference to FIG. 1 will show that for rectangular pulses the curve starting at the rheobase value at first is substantially horizontal.

When counter 20 has again reached the position wherein a zero signal appears at the predetermined reset counting output terminal, the resetting of counter 12 is stopped and counter 16 is advanced by one step. This again causes motor 34 to be activated and table 31 to be moved to the next position. Again, the signal from photo-transistor 27 serves as a fine positioning signal which stops the motor and causes pulse generator 18 to be activated as described above. The holes 35 in the table of course are bored in such a manner that each of the holes indicates the correct positioning in the x direction. Thus line x.sub.2 will be directly aligned with the lamp bank when the next signal appears on phototransistor 27. The pulse width furnished by pulse generator 18 now is the pulse width and pulse interval determined by count x.sub.2 on counter 16. This is a shorter pulse width and possibly also a shorter pulse interval. Again, pulses are applied to the patient with the pulse width and interval determined by pulse generator 18. Again, the amplitude of the pulses depends upon the output of counter 12. This amplitude is increased as stated previously after a predetermined number of identical pulses has been applied to the patient. Upon observance of the minimum muscle movement either the response of stage 30 or the closing of switch 29 causes the counters and pulse generators to be reset and deactivated as stated above. The lamp lit along the line x.sub.2 then indicates the value of y which is to be entered on the diagram. This process is then repeated for other points in FIG. 1.

In order to find the value required for the chronaxie, the procedure is the following: As mentioned above, pulses of twice the amplitude as the rheobase are applied to the muscle and the pulse width is increased until the minimum muscle twitching appears.

The portion of the apparatus for carrying out this procedure is shown in FIG. 3. First, start switch 38 is activated, causing bistable circuit means 25 to switch to the second stable state. Switching the bistable circuit means 25 also causes counter 16 to be advanced to its end count, namely count x.sub.14, at which the minimum pulse width is furnished by pulse generator 18. The output at counter terminal x.sub.14 causes the motor to be energized, thereby moving table 31 into the position wherein point x.sub.14 is lined up with the lamp bank. The amplitude of the pulses applied to the patient is so adjusted that it is double the amplitude as was obtained by the rheobase measurement. Activation of the pulse generator 18, following correct position of the table, then causes short pulses to be delivered to the patient. Again, a predetermined number of equal pulses is applied to the patient until the count on counter 16 is changed. As previously stated enough time must be allowed, especially if the stop is manually operated, to allow the observer to see the muscle movement and to react thereto.

The number of so-applied equal pulses depends upon the count on counter 16. This is accomplished by providing a counter 39 which counts the number of pulses furnished by pulse generator 18. The counter is preset to a number corresponding to the count on counter 16. When counter 39 reaches zero, it furnishes a pulse to counter 16 which causes this counter to count backwards by one unit. Simultaneously, counter 39 is again set to its initial condition corresponding to the new count on counter 16, causing pulse generator 18 to deliver a corresponding number of equal pulses having a slightly longer pulse width than the previously applied pulses. If no muscle movement is observed, the procedure is repeated until such muscle movement is observed, switch 29 is activated or unit 30 responds. The point on the diagram determined by the positioning of table 31 and the lighting of one of the lamps 13 can then be entered into the diagram.

The apparatus has a "repeat" key which causes the whole process to be repeated automatically for any desired point, so that the obtained values may be checked.

The individual units shown in FIGS. 2 and 3 and their interconnection will now be described in greater detail with reference to FIGS. 4-9.

FIG. 4 is a circuit diagram of control pulse generator means 18, pulse generator 18 comprises a monostable multivibrator having transistors 40 and 41. The base of transistor 40 is connected to the collector of transistor 41 by means of a capacitor 42, while the base of transistor 41 is connected to the collector of transistor 40 by means of a resistor 43. Base of transistor 40 is connected through a resistor 44 to the common plus line 45, while the emitter of transistor 40 is connected to the common minus line 46. The collector of transistor 40 is connected through a resistor 47 to the plus line 45. The emitter of transistor 41 is also connected to the plus line 45 and the collector of transistor 41 is connected to the minus line 46 by means of a voltage divider comprising resistors 48 and 49. The collector-emitter circuit of a switching transistor 50 is connected in parallel to the base-emitter circuit of transistor 41. The base of transistor 50 is connected to the positive line through a resistor 51 and is also connected to the base 2 of a unijunction transistor 52, whose first base is connected to minus line 46. The emitter of unijunction transistor 52 is connected to a terminal 56. Terminal 56 is connected to the collector of a transistor 54 whose emitter is connected to minus line 46. Terminal 56 is also connected to one terminal of a capacitor 55 whose other terminal is connected to minus line 46. The collector of a transistor 53 is also connected to terminal 56, while its emitter is connected to the plus line through a resistor 59. The base of transistor 53 is connected to the tap of a voltage divider comprising a Zener diode 57 and a resistor 58. The output of second NAND-gate 26 is applied to the base of transistor 54.

The operation of the above-described pulse generator 18 is as follows:

When a O signal appears at the output of second NAND-gate 26, which signal has approximately the potential of minus line 46, then transistor 54 is blocked and capacitor 55 is charged through the collector-emitter circuit of transistor 53 and resistor 59. The current charging capacitor 55 of course is determined not only by resistor 59 but by the voltage divider ratio of the voltage divider having Zener diode 57 and resistor 58. Under these conditions transistors 40 and 41 of the monostable multivibrator are in the conductive state so that substantially the full positive potential appears at the collector of transistor 41 and thus at the right-hand electrode of capacitor 42. Similarly, the left-hand electrode of capacitor 42 is the potential determined by the minus line 46. When the voltage across capacitor 55 reaches a predetermined value, the internal base resistance of double base diode 52 is greatly reduced for a short time and capacitor 55 discharges through double base diode 52. Thus a negative pulse is applied to the base of transistor 50, causing this transistor to be switched to the conductive state. This in turn causes the base of transistor 41 to receive a positive signal, blocking transistor 41. This causes the potential at the collector of transistor 41 and thus at the right-hand electrode of capacitor 42 to become substantially equal to the negative potential available on line 46. The voltage on the left-hand electrode of capacitor 42 is still more negative than this value by approximately the operating voltage. Thus transistor 40 is also blocked and remains blocked until capacitor 42 has recharged through resistor 44 to such a point that the potential on the left electrode is sufficient to switch transistor 40 to the conductive state. This causes transistor 41 to become conductive again also and capacitor 42 recharges to its original potential.

The above-described process is repeated when the voltage across capacitor 55 again has reached the value for causing unijunction transistor 52 to become conductive. The voltage generated at terminal 56 to have a substantially exponential form. Corresponding to this exponential form, the output shown at terminal 60 and terminal 61 is a rectangular pulse sequence, the amplitude at terminal 60 being approximately twice the amplitude appearing at terminal 61.

Changes in the pulse width and the pulse interval of the pulses are accomplished by changing the resistors and the capacitors in the above-described circuit. The pulse width depends at least in part on the values of resistors 59 and capacitors 55, while the pulse interval depends at least in part on the value of resistor 44 and capacitor 42. How these are changed will be shown in the description of FIG. 6.

With reference to FIG. 5, it will now be shown how the amplitude of the pulses applied to the patient is made to vary as a function of the output of counter 12. FIG. 5 shows the circuitry required for this purpose. Specifically, FIG. 5 shows the amplitude control circuit means, namely transistors 62 and 63 and the associated resistors as well as output switch means 60 and the symbolically shown electrode 67. Transistors 62 and 63 serve only as an illustration. A much larger plurality of such transistors would of course be used, namely one for each counting output of counter 12. Specifically, the emitters of transistors 62 and 63 are connected in common to the minus line 46, while the collector of transistor 62 is connected to the emitter of a transistor 66 constituting output switch means through a resistor 64 while the collector of transistor 63 is connected to said emitter via a resistor 65. The collector of transistor 66 is connected to the electrodes shown in symbolic form as a resistor 67 to the voltage source denoted by U.sub.2. The output of the pulse generator 18, namely terminal 60, is applied to the base of transistor 66.

The base of transistors 62 and 63 are connected to the respective counting outputs of counter 12 through resistors 68 and 69 respectively. Counter 12 may be any conventional counter and comprise bistable circuits in each counting stage. Further, each counting output y.sub.1 -y.sub.n is connected to the base of a transistor 73, 72, etc. through resistors 71, 70 respectively. The emitters of transistors 73 and 72 are connected to ground potential, while the collectors are connected to the positive line through lamps 13. Transistors 73, 72, etc., operate as amplifiers. Thus when counter 12 furnishes a signal output y.sub.1, transistor 73 becomes conductive causing lamp 13 to light. The lighting of the lamp thus indicates the state of counter 12. This in turn gives an indication of the amplitude of the pulses applied to the patient since transistor 63 is also put into the conductive state by a signal at terminal y.sub.1 and causes current to flow upon application of a pulse to the base of transistor 66 which current depends upon resistor 65. Thus the current flowing through resistor 67 (which symbolizes the muscle of the patient) has an amplitude depending upon the state of counter 12 and a pulse width and interval depending upon the output of pulse generator 18. When the signal at counting output y.sub.1 disappears and the signal at counting output y.sub.2 appears, the amplitude of the current is determined by resistor 64, since transistor 62 will then be conductive.

FIG. 6 shows the circuitry which is required to change the pulse width and interval in dependence on the count of counter 16. It should be noted that terminals a, b, c and d in FIG. 4 are the same as those shown in FIG. 6. The top line of FIG. 4 is the plus line, while the bottom line is ground potential. Referring now to FIG. 6, it is seen that the outputs x.sub.1, x.sub.2 . . . x.sub.m of counter 16 are connected in pairs to the inputs of OR-gates 74 whose outputs are connected through base resistors 75 to the bases of transistors 76. Although only two transistors 76 are shown for each element which may be varied (capacitor 55, resistor 59 and resistor 44) more of such transistors and associated elements may of course be furnished. In any case each count on counter 16 results in the energization of at least one OR-gate 74 for each of the above-mentioned elements. When a positive signal is passed through the OR-gate 74, the associated transistor 76 becomes conductive connecting the associated element (for example 55') into the circuit. Since elements 59 and 44 do not have any connection to ground potential, an additional transistor 76' must be provided for each of these components. Specifically, the transistor 76 which is associated, for example, with resistor 59', has a voltage divider circuit in its collector circuit. Connected to the tap of the voltage divider is the base of a transistor 76' whose emitter-collector circuit is connected from the positive line (terminal b) to one terminal of resistor 59' whose other terminal is connected to point a of FIG. 4. When transistor 76 becomes conductive, the voltage at the base of transistor 76' drops causing this transistor also to become conductive. This of course connects element 59' into the circuit of FIG. 4. Resistors 44' are connected into the circuit of FIG. 4 in the same fashion, except that the switching transistor which switches these between points d and c in FIG. 4 is labelled 76" in FIG. 6. It best becomes evident that with a circuit such as shown in FIG. 6, the width and the interval between the pulses furnished by pulse generator 18 as shown in FIG. 4 may be varied over extremely wide ranges.

FIG. 7 shows one embodiment of the automatic stop means labelled stage 30 in FIGS. 2 and 3. The circuit shown in FIG. 7 shows a capacitive pickup 77 which is connected to the patient. The pickup, denoted by capacitor 77, forms part of a voltage divider whose other portion is embodied in a resistor 78. The voltage divider tap of this voltage divider is connected to the emitter of a field effect transistor 79 whose output is smoothed by a low pass filter 80. The output of low pass filter 80 is in turn connected to the input of a threshold stage 81. When the threshold of threshold means 81 is passed, threshold circuit 81 furnishes the proper signal for deactivating pulse generator 22 and counters 17, 20 and 39. This signal of course results when the signal at the input of field effect transistor 79 changes due to muscle contraction in the patient.

FIG. 8 shows the control circuit for controlling motor 34 which drives table 31. The direction of rotation of motor 34 is determined by the setting of a switch 34'. The remainder of the circuit is used to start and stop the motor. Specifically, both the forward and the reverse counting input of counter 16 are connected to the input of an OR-gate 82 whose output is connected to the switching input of a monostable multivibrator 83. An output of monostable multivibrator 83 is connected through a resistor 84 to the base of a transistor 85 whose emitter-collector circuit is connected in series with a resistor 86 and a light source 37, here a gallium-arsenide light emitting diode, the so-formed series circuit being connected from ground to the positive line. The emitter-collector circuit of a phototransistor 27 is connected to plus line 45 by means of a resistor 87 and is further connected to the base of a transistor 89 through a resistor 88. The emitter-collector circuit of transistor 89 is connected from positive line 45 to ground. Transistor 89 forms part of a bistable stage which also includes transistor 90 and resistors 91 and 92. Specifically, resistor 91 is connected from the base of a transistor 89 to the collector of the transistor 90, while resistor 92 is connected from the collector of transistor 89 to the base of transistor 90. Further, the emitter-collector circuit of a transistor 93 is connected between the base and emitter of transistor 90, the base of transistor 93 being connected to the collector of transistor 85. The emitter of transistor 90 is connected to ground potential, while its collector is connected to the coil of a relay 91 whose other terminal is connected to plus line 45. Relay 91 controls contacts 95 which, when closed, short circuits motor 34. The above-mentioned switch 34' which determines the direction of rotation of motor 34 is connected in parallel with said motor and contacts 95.

The above-described circuit operates as follows:

When a pulse is received at either the forward or reverse counting input of counter 16, that is when the count on counter 16 is changed in either direction, this pulse is transmitted through OR-gate 82 to the monostable multivibrator 83, thereby switching this monostable multivibrator to the unstabled state. At this time, transistor 85 is blocked, blocking the current flow through diode 37 and therefore causing diode 37 to stop the emission of light. Therefore, no more light is received by phototransistor 27 and this transistor blocks. However, the blocking of transistor 85 has caused a positive potential to be applied to the base of transistor 93, causing this transistor to become conductive. This causes a negative potential to be applied to the base of transistor 90 causing this to block. Therefore, relay 91 is deenergized and contacts 95 open. Motor 34 will commence to run in the direction indicated by switch 34. This causes table 31 to move until a hole 35 in the rod 36 affixed to table 31 causes light to be transmitted from diode 37 to phototransistor 27. It should be noted that the time constant of monostable stage 83 is so arranged that diode 37 is again energized prior to the time that the next hole is positioned in front of diode 37. Thus phototransistor 27 becomes conductive and a negative signal is applied to the base of transistor 89 causing transistor 89 and, therefore, transistor 90 to become conductive. Thus current again flows through the coil of relay 91 causing contacts 95 to close thereby stopping motor 34.

The interconnection between counters 16, 17 and 12 is shown in FIG. 9. Two flip-flop stages 103 and 104 of counter 16 are shown. Flip-flop stage 103 has an output 110 and a second output 111 while flip-flop stage 104 has an output 112. Counter 17 further comprises two AND-gates, 107 and 108, two OR-gates 105 and 106, and a further AND-gate 109. The output of gate 109 furnishes the counter advance signal to counter 12. Specifically, this signal is furnished on a line 114 and it must be noted that counter 12 advances each time the signal on line 114 changes from a zero to a one state. AND-gates 107 and 108 each have a plurality of inputs connected with specific counting stages of counter 16 as will be discussed below. The output of AND-gate 107 is connected to one input of OR-gate 105 whose other input is connected to output 110 of flip-flop 103. Similarly, the output of AND-gate 108 constitutes one input of OR-gate 106 whose other input is connected to output 112 of flip-flop 104. The outputs of OR-gates 105 and 106 constitute the inputs to AND-gate 109 whose output, as discussed above, constitutes the counter advanced signal when changing from a zero to a one state.

The above-described arrangement operates as follows:

Initially it is assumed that counter 16 has a specified output at output x.sub.1, that is for example a zero potential output. This indicates that two identical pulses are to be applied to the patient before any changes in amplitude occur. Pulse generator 18 (after depression of key 38) delivers a pulse sequence 116 to the input 102 of counter 17.

Initially output 110 of flip-flop 103 carries a I signal, output 111 a zero signal and output 112 of flip-flop 104 also carries a I signal. Only output x.sub.1 of counter 16 carries a zero signal, that is outputs x.sub.2 . . . x.sub.m all have a "1" potential. Thus the output of AND-gate 104 is a "1" potential which does not serve to advance counter 12, as stated previously, this counter responds only to changes from "0" to "1" on line 114.

As shown in FIG. 9, the first pulse in the first sequence 116 has a trailing edge 115. This trailing edge 115 causes flip-flop 103 to flip, that is output 110 now carries a "0" output, while output 111 is fliped from the "0" to the "1" state. The state of flip-flop 104 is unchanged since this flip-flop reacts only to a change from "1" to "0." Both inputs of OR-gate 105 thus have a "0" signal which causes a "0" signal to appear at its output in turn causing a "0" signal to appear on line 114. Counter 12 is not sensitive to change of state from "1" to "0." The trailing edge 117 of the second pulse in pulse sequence 116 again causes flip-flop 103 to flip. Output 110 therefore changes from a "0" to a "1" state while output 111 changes from a "1" to a "0" state. OR-gate 105 receives a "1" signal from output 110 and therefore furnishes a "1" signal to AND-gate 109. Flip-flop 104 is sensitive to the change from "1" to "0" experienced at output 111 and therefore also changes state, that is output 112 changes from "1" to "0." Since its second input still carries a "1" signal, OR-gate 106 continues to furnish a "1" signal to AND-gate 109 causing the signal on line 114 to change from a "0" to a "1" state, thereby advancing counter 12 by one step.

Thus counter 12 is advanced for every other pulse in pulse sequence 116. Once counter 16 has passed counting stage x.sub.4, all outputs x.sub.1, x.sub.2, x.sub.3 and x.sub.4 carry a positive potential which cause AND-gate 107 and therefore OR-gate 105 to furnish a 1 signal without interruption. During the four subsequent pulses in pulse sequence 116 one of the outputs x.sub.5 . . . x.sub.8 has a 0 potential. Thus the signal on line 114 will remain at 0. Following the fourth pulse flip-flop 104 changes state, causing a 1 signal to appear at output 112, which in turn causes a 1 signal to appear at the output of OR-gate 106 and on line 114. This change from 0 to one on line 114 causes counter 12 to advance by one step. FIG. 9 thus illustrates how the given number of pulses applied to the muscle at any amplitude as determined by the state of counter 12 depends upon the counting state of counter 16. FIG. 9 only shows two stages of counter 17. Of course further stages will be required in a practical case.

The interconnection between 18 and 16 and 39 of course can be carried out in an analogous fashion. Under those circumstances the counter indicated as counter 17 in FIG. 9 would correspond to counter 39 of FIG. 3. The output of AND-gate 109 would be connected to the counting input of counter 16, whose outputs x.sub.1 . . . x.sub.m would be connected to AND-gates 107 and 108 as in FIG. 9.

It will be noted that the indicating arrangement shown in the drawing and comprising table 31 which is moved perpendicular to the axis of a lamp bank 32 constitutes only one possible embodiment. It is of course equally possible to record the results of the measurements by means of known x-y recorders, the count on counter 12 constituting one coordinate while the count on counter 16 constitutes the other coordinate of a measuring point. Further, the points can be indicated by a field of light sources in which every possible point, namely all the intersections of lines x.sub.1 to x.sub.n with lines y.sub.1 to y.sub.n are represented by a lamp. Logic circuit means can then be used to cause that particular lamp to light up which has the coordinate x.sub.1 corresponding to the count of counter 16 and the coordinate y corresponding to the count on counter 12.

While the invention has been illustrated and described as embodied in a specific indicator and counting circuit, it is not intended to be limited to the details shown, since various structural and curcuit changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

Claims

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. Diagnostic apparatus for generating points of minimum involuntary muscle movement as a function of amplitude and duration of electrical pulses applied to said muscle for entry of an intensity-time diagram, comprising, in combination, adjustable pulse generator means for furnishing a sequence of pulses, each of said pulses having an amplitude and a pulse width; electrode means connected to said adjustable pulse generator means and adapted to be placed in operative proximity of said muscle for applying said pulses thereto; control means connected to said adjustable pulse generator means for controlling said pulse width to one of a number of selectable pulse widths; first counting means connected to said pulse generator means, for counting said pulses and automatically changing said amplitude of said pulses following receipt of a given number of said pulses; varying means connected to said first counting means, for varying said given number in dependence upon said pulse width of said pulses; and stop means for stopping said first counting means upon appearance of said involuntary muscle movement, said amplitude and said pulse width of said pulses of said adjustable pulse generator means at appearance of said involuntary muscle movement constituting the coordinates of one of said points of minimum involuntary muscle movement.

2. Apparatus as set forth in claim 1, wherein said stop means comprise manually activated switch means for activation by the operator of said apparatus upon observance of said involuntary muscle movement.

3. An arrangement as set forth in claim 1, wherein said stop means comprise sensor means for sensing said involuntary muscle movement and furnishing a corresponding stop signal.

4. Apparatus as set forth in claim 1, wherein said adjustable pulse generator means comprise a source of current, output switch means for connecting said source of current to said electrode means when activated, and control pulse generator means for furnishing control pulses for activating said output switch means.

5. Apparatus as set forth in claim 4, wherein said output switch means comprise semi-conductor switch means.

6. Apparatus as set forth in claim 4, wherein said control pulse generator means comprise first timing means for determining the pulse width of said control pulses; and wherein said control means comprise additional timing means, and timing switch means for connecting said additional timing means to said control pulse generator means for varying the pulse width thereof.

7. Apparatus as set forth in claim 6, wherein said timing switch means comprise timing counter means.

8. Apparatus as set forth in claim 7, wherein said first counting means comprise amplitude control counting means furnishing counting output signals each signifying a predetermined multiple of said given number of electrical pulses, and amplitude control circuit means connected between said amplitude control counting means and said source of current, for varying the amplitude of said electrical pulses in dependence upon said counting output signals.

9. Apparatus as set forth in claim 8, wherein said first counting means further comprise control pulse counting means connected to said control pulse generator means, for counting said control pulses and furnishing a counter advance signal advancing the count on said amplitude control counting means when the number of so-counted control pulses is equal to said given number.

10. Apparatus as set forth in claim 9, further comprising first connecting means connected between said timing counter means and said amplitude control counting means for varying said given number in dependence upon the output of said timing counter means.

11. Apparatus as set forth in claim 10, further comprising means resetting said control pulse counting means in response to said counter advance signal.

12. Apparatus as set forth in claim 11, further comprising reset means connected to said amplitude control counting means for resetting said amplitude control counting means a predetermined number of counts in response to each activation of said reset means.

13. Apparatus as set forth in claim 12, wherein said amplitude control counting means has a reverse counting input; and wherein said reset means comprise second pulse generator means for furnishing a sequence of reset pulses upon activation, reset pulse counting means for counting said reset pulses and for furnishing corresponding reset counting output signals, and means for applying said reset pulses to said reverse counting input of said amplitude control counting means and for blocking the application of said reset pulses to said reverse counting input in response to a predetermined one of said reset counting output signals.

14. Apparatus as set forth in claim 13, wherein said means for applying and blocking said reset pulses from said reverse input comprise AND-gate means.

15. Apparatus as set forth in claim 14, wherein said reset pulse counting means furnish said predetermined one of said reset counting output signals at a predetermined reset counting output terminal; wherein said timing counter means has a forward counting input; further comprising inverter means connecting said predetermined reset counting output terminal and said forward counting terminal of said timing counter means.

16. Apparatus as set forth in claim 15, further comprising additional inverter means connected to the output of said AND-gate means; and additional AND-gate means having a first input connected to the output of said additional inverter means, a second input connected to the output of said control pulse generator means, and an output connected to the input of said control pulse counting means, whereby said predetermined reset couting output signal causes said additional AND-gate means to become conductive and permit the application of said control pulses to the input of said control pulse counting means.

17. Apparatus as set forth in claim 16, wherein said stop means furnish a stop signal for terminating the operation of said second pulse generator means and for resetting said reset pulse counting means and said control pulse counting means.

18. An arrangement as set forth in claim 17, wherein said stop means comprise manually activatable switch means.

19. An arrangement as set forth in claim 17, wherein said stop means comprise electromechanical transducer means.

20. Apparatus as set forth in claim 19, wherein said electromechanical transducer means comprise capacitor winding means applied in operative vicinity of said muscle, circuit means connected to said capacitance pickup means to furnish an electrical signal in response to capacitance changes resulting from said involuntary movement of said muscle, filter means for filtering said electrical signal, and threshold means connected to the output of said filter means.

21. Apparatus as set forth in claim 20, further comprising start signal furnishing means; bistable circuit means connected to said start signal furnishing means and having a "0" output connected to said timing counter means for setting said timing counter means to a determined count and a "1" output; NAND-gate means having a first input connected to said "1" output of said bistable circuit means, a second input connected to said predetermined reset counting output terminal and an output connected to said control pulse counting means; and additional control pulse counting means for counting said control pulses and for advancing said timing counter means in response to a predetermined number of so-counted control pulses, said predetermined number varying as a function of the count on said timing counter means, said additional control pulse counter means having reset means for resetting said additional control pulse counting means upon receipt of said predetermined number of control pulses.

22. Apparatus as set forth in claim 23, wherein said stop means furnish a stop signal resetting said bistable means to furnish said "0" output.

23. Apparatus as set forth in claim 22, further comprising means interconnecting said stop means and said additional control pulse counting means for causing said stop signal reset said additional control pulse counting means.

24. Apparatus as set forth in claim 1, further comprising means for indicating said points on said intensity-time diagram, said means comprising a plurality of lamp means each connected to a corresponding output of said amplitude control counting means, lamp back means for supporting said lamps, each in a predetermined position relative to the other of said lamps, recording means for having said intensity-time diagram inscribed thereon positioned to receive light from said lamp means, table means for supporting said recording means, and moving means for moving said table means in a direction perpendicular to said lamp bank means, to a position corresponding to the output of said timing counter means.

25. Apparatus as set forth in claim 24, further comprising fine positioning means for furnishing an exact adjustment of the position of said recording means relative to said lamp bank means.

26. Apparatus as set forth in claim 25, wherein said moving means comprise motor means; wherein said table means has a plurality of markings in the direction perpendicular to the axis of said lamp bank means; and wherein said fine positioning means comprise sensor means for sensing said markings and furnishing a marking signal in response thereto, and connecting means connecting said sensor means to said motor means for stopping said motor means in response to said marking signal.

27. Apparatus as set forth in claim 26, wherein said sensor means comprise photoelectric sensor means.