Abstract:
An audible electroencephalograph (EEG) for use with electroconvulsive therapy (ECT). A voltage controlled oscillator converts the magnitude of the signal received from the patient&#39;s brain into an audible tone indicative of brain activity. The tone undergoes frequency modulation about 500 hertz to indicate to the attending physician the brain seizure produced by the ECT. The audible signal informs the physician of the results of the ECT without requiring any attention to or waiting for a strip recorder to provide a graphic display. This permits the physician to continuously watch the patient during the ECT. Used in conjunction with the ECT equipment, a first, warning tone may indicate a short hiatus between pressing the treatment button and the commencement of the ECT stimulus. A second tone indicates the application of the ECT stimulus, while the third tone, as described above audibly delineates the resulting effect upon the patient.

Description:
BACKGROUND 
     Electroconvulsive therapy (ECT), more colloquially known as electric shock treatment, finds use in modern psychiatry for patients suffering from severe depression or melancholia. A description of the indications for ECT as well as present techniques appears in the booklet Thymatron™ Instruction Manual by Richard Abrams, M.D., and Conrad Swartz, Ph.D., M.D., (May 1985), published by Somatics, Inc., 910 Sherwood Drive, Unit 18, Lake Bluff, Ill. 60044, and the references cited there. 
     During ECT, the patient remains under anesthesia. Accordingly, he may exhibit no physical movement during the seizure induced by the ECT. Accordingly, the physician should follow the course of treatment through information provided by an electroencephalogram (EEG) taken during treatment. 
     The ECT, to produce the required therapeutic effect, should generally produce a seizure which lasts at least 25 seconds. If the seizure lasts less than this time, the physician often repeats the ECT with a larger electrical dosage to achieve the therapeutic benefit for the patient. 
     The EEGs currently in use provide a readout of the patient&#39;s brain activity drawn by a line on a strip of paper. To obtain this information, the physician must direct and keep his attention to the recoder producing the graph. To the extent that he does so, he can not devote his undivided attention to the patient undergoing the ECT or to his vital signs. Also, only one person can usually review the graph. 
     Additionally, the mechanism for driving the paper becomes subject to the normal wear and tear through time. It may, in fact, prove unworkable when actually needed during ECT. 
     Furthermore, the equipment utilizes electroencephalograph paper. This of course, must undergo replacement at regular, frequent intervals. 
     Also, interpreting the paper EEG record requires substantial sophistication and technical expertise. Moreover, it requires time to study the graph in order to arrive at a determination as to the effectiveness of the ECT. 
     SUMMARY 
     Providing the results of EEG in audible form will permit the instantaneous following of the course of the ECT treatment by an attending physician. Moreover, he will not have to remove his attention from the patient in order to obtain this vitally needed information. 
     To produce the audible tone, the EEG device should include a transducer which detects the brain activity of a patient. The transducer, based on the information it receives from the patient, produces a first electrical signal external to that patient. The signal, of course, has an amplitude proportional to the magnitude of the detected brain activity. 
     A converter then couples to the transducer and produces a second electrical signal having an a.c. character. The second signal has a frequency defined as a function of the amplitude of the first signal produced by the transducer. 
     An audibilizer represents a third component of the EEG device and couples to the converter. The audibilizer converts the second electrical signal to an audible signal reflective of the second electrical signal&#39;s frequency. 
     Typically, the resulting audible tone has a frequency equal to the a.c. signal produced by the converter. As the magnitude of the detected brain activity varies, so will the frequency of the second electrical signal produced by the converter and thus the tone generated by the audibilizer. The physician then listens to the tone and obtains a direct indication of the patient&#39;s brain activity during a seizure induced by ECT. 
     The method of discerning the effect of electroconvulsive therapy upon a patient commences with the detection of the brain activity of a patient. The method then requires the producing of a first electrical signal having an amplitude proportional to the magnitude of the brain activity detected in the patient. 
     From the first electrical signal, a second a.c. electrical signal must result which will have a frequency defined as a function of the amplitude of the first signal. Lastly, the second electrical signal should undergo conversion to an audible signal. This last audible signal must indicate the frequency of the second electrical signal and, thus, the magnitude of the induced brain activity. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 gives a block diagram of EEG-ECT equipment providing an audible electroencephalograph. 
     FIG. 2 shows the leads and the differential amplifier circuit of the audible EEG section of the equipment shown in FIG. 1. 
     FIG. 3 gives the notch filter circuit of the EEG section of the equipment shown in FIG. 1. 
     FIG. 4 shows the amplifier and the low-pass filter circuitry of the EEG section of the equipment of FIG. 1. 
     FIG. 5 displays the EEG oscillator and ECT warning and therapy-application tone generator as well as the audio amplifier circuit of the equipment shown in FIG. 1. 
     FIG. 6 shows the control circuitry for the EEG-ECT equipment of FIG. 1. 
     FIG. 7 gives a circuit diagram for the power supply, including the electricity used in the ECT section, of the equipment shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a block diagram generally at 10 for an ECT-EEG device that will produce an audible EEG. Naturally, the diagram includes the plug 11 for receiving the usual a.c. mains current, the fuse 12, and the on-off switch 13. 
     The power supply block 14 provides the necessary voltage and current for the remaining portions of the instrument. It also delivers the electrical current required for the actual ECT. The current for ECT passes to the box 15 which includes the relays and the input switching which connects the power to the ECT leads 16 attached to the patient. 
     After the application of the ECT electricity, the brain exhibits drastically altered electrical activity detected by the EEG leads 17. After passing back through the switching box 15, the EEG signal travels to the EEG amplifier 18 and then the sound box 19 which provides the audible tone on the loudspeaker 20. The volume control knob 21 permits the physician to adjust the volume to an acceptable level. 
     The control of the circuits shown in FIG. 1 occurs in the box 22. To initiate an ECT, the physician depresses the treatment button 23. This induces the remainder of the circuit to provide ECT and determine the results through the EEG section. The percentage knob 24 on the control box 22 determines the amount of electrical shock received by the patient. 
     Lastly, prior to the patient actually undergoing ECT, the impedance between the electrodes placed on his head should be tested. The equipment shown in FIG. 1 does this through the impedance box 25. The physician presses the test button 26 and obtains a reading of the patient&#39;s impedance through the meter 27. A low impedance generally will indicate a short circuit between the electrodes through, for example, wet hair on the patient. 
     In FIG. 2, the EEG leads L1 and L2 attach to the patient over the front of the forehead. These, of course, detect the brain&#39;s electrical activity. The ground lead L3 attaches to a location of the patient&#39;s body remote from his head, for example his shoulder. 
     The EEG becomes effective after the application of the ECT stimulus. A switching mechanism in the instrument prevents the operation of the EEG during ECT stimulus. 
     Furthermore, as discussed below, the equipment itself produces three different sounds. When the physician depresses the treatment button to commence the ECT, the instrument gives a warning sound for approximately one second. During this time, the patient receives no ECT. If the physician releases the button during this period of time, no ECT results. 
     However, if the physician continues to depress the treatment button beyond the duration of the warning, then ECT commences. A second tone, appreciably different from the warning sound, emanates from the equipment during the actual ECT stimulus. 
     At the termination of the ECT stimulus, the instrument switches to the EEG mode to determine the effect of the ECT. It then emits a tone indicative of the actual course of the brain activity of the patient subsequent to the ECT stimulus. 
     Returning to FIG. 2, the diodes D1 to D4 and the resistors R1 and R2 protect the EEG amplification electronics for the ECT stimulus. Otherwise, the voltage from the ECT stimulus could damage the remaining components. 
     FIG. 2 provides a low-noise differential amplifier for the difference in the signals received by the leads L1 and L2. The field-effect transistors Q1 and Q2 amplify the signal while providing a high input impedance. The operational amplifiers Z1 and Z2 provide negative feedback to the FETs Q1 and Q2 for stability. 
     At the right end of FIG. 2, the operational amplifier Z3 produces, as its output, a single signal characteristic of the difference between the two input signals derived ultimately from the leads L1 and L2. The output, appearing on the lead A, then travels to the circuit shown in FIG. 3. In FIG. 2, the positive voltage +V appears at +15 volts while, in the other figures, the negative voltage -V stands at -15 volts. 
     In FIG. 2, the circuitry amplifies the signal 1000 times through the low-noise, differential amplifier. The amplifier has a 2 to 3000 thousand Hertz band width and a common mode rejection of 80 dB. 
     The circuitry in FIG. 3 simply operates as a notch filter to remove any 60 Hertz signal. This frequency corresponds to the usual house current. The output of FIG. 3, on this lead B, appears at the input of FIG. 4. 
     The signal, in FIG. 4, receives amplification by a factor of 10. It then enters a 0 to 25 Hertz low-pass filter which includes the operational amplifier Z9. The operational amplifier has a 30 dB per octave rolloff. 
     The signal produced by the circuitry of FIG. 4 on the lead C enters FIG. 5. At this point, it takes the characteristics of a normal EEG signal. The signal passes to the voltage controlled oscillator Z11 which first generates a 500 Hertz audio carrier wave. Generally, the carrier wave should fall in the easily audible range of about 200 to 1000 Hertz. The oscillator Z11 also acts as a voltage-to-frequency convertor, transforming the amplitude of the voltage to a modulation of the 500 Hertz audio carrier to produce the audible tone. The potentiometer R48 permits the operator to adjust the volume as appropriate for the particular location. 
     The connection F comes from the control circuitry of FIG. 6. It receives a signal that will turn on the audible EEG after the application of the ECT stimulus. 
     The connections D and E of FIG. 5 connect to the chip Z14 in order to provide the other audible tones from the instrument during the course of treatment. The latter connection E provides an input that will result in an audible tone during the period that the physician pushes the treatment button but before the actual application of ECT. The upper connection D provides the different tone which emanates from the equipment during the actual ECT application. 
     In the control circuitry shown in FIG. 6, the connection I leads to the treatment button. The diodes D8 and D9 prevent &#34;bounce&#34;, or double action, on a single depression of the button. Depressing the treat button causes the 555 timer chip Z17 to issue a signal which travels to the connection E shown in FIG. 5 to create the one-second warning signal. 
     The same signal also travels to the flip flop Z16 which, after one second, changes its state to turn on. The output of the flip flop Z16, after amplification, lights a bulb on the equipment during the actual ECT. The leads G and H connect the treatment dial poles through the AND gate Z15 to the flip flop Z16. 
     The signal from the chip Z17 also travels to the chip Z18 which establishes the stimulation frequency of 140 pulses per second for the ECT. 
     Furthermore, the signal from the chip Z17 also travels to the chip Z19. There, it sets the width of the ECT stimulus pulse. Each pulse has a width of one millisecond. 
     The flip flop Z23 changes state with each pulse, causing the ECT stimulus pulse to the patient to alternate between positive and negative. The flip flop Z25 turns on the audible EEG at the end of the ECT stimulus. The flip flops Z22 and Z24 count the pulses of ECT stimulus. The flip flop Z22 also receives the setting on the treatment dial to establish the actual length of the ECT stimulus. 
     
                       TABLE______________________________________Components Used in the FiguresIdentification         Component______________________________________C1-C4, C13-C15, C17-C22,                  .01 μfC24C5                     1.0 μfC6, C7                 .033 μfC8, C12, C25           .056 μfC8&#39;, C16, C23          .1 μfC9                     .027 μfC10                    .18 μfC11                    .018 μfC26                    2600 μfC27, C28, C31          1000 μfC29, C30               22 μfD1-D4                  1N4404D5-D11, D13-D17        1N4004D12                    1N4734AF1                     1.5 AF2                     5 AL1-L3                  CN502L4, L5                 K301Q1, Q2                 2N5566Q3, Q4, Q6, Q7         2N4401Q5                     2N4403Q8                     2N5401Q9                     1RF712Q10, Q12, Q14          MJ15024Q11, Q13               1RF511R1, R2, R14, R15, R29, R31,                  100K ΩR43, R44, R47, R50, R53-R55,R57, R62, R70, R78, R79R3, R4, R59            10 M ΩR5, R6                 49.9 ΩR7                     100 ΩR8, R10, R11, R13, R30, R37-                  10K ΩR40, R45, R48, R49, R56, R58,R63, R67, R71, R73, R74, R76R9, R10, R16, R17, R24, R51                  1K ΩR18, R27               49.9K ΩR19                    45.2K ΩR20                    5K ΩR21, R61, R72          1 M ΩR22                    806K ΩR23                    3.3K ΩR25                    1.62 M ΩR28, R65               50K ΩR32-R34                120K ΩR35                    110K ΩR36                    102K ΩR41, R60, R66          22K ΩR42                    5.6K ΩR46                    81K ΩR52                    2K ΩR64                    39K ΩR68                    82K ΩR69                    20K ΩR75                    .62 Ω, 10 W.R77                    47K ΩT1                     241-48-7T2                     241-36-6T3                     241-24-8V                      LA130-10Z1-Z10, Z13            TL074Z11                    1CL8038Z14, Z17-Z19           MC1455Z15                    1N4004Z16, Z23-Z25           4013Z20, Z21               4081Z22, Z26, Z27          4017Z28, Z29               BR-62Z30                    7815Z31                    7915______________________________________ 
    
     The outputs from the AND gates Z20 and Z21 pass along the leads J and K to the power circuitry of FIG. 7. The signal on these connections control the release of the electrical stimulus for the ECT to the patient. 
     The power circuitry of FIG. 7 eventually delivers the actual electrical stimulus to the leads L4 and L5 connected to the patient. As discussed before, this section also provides the output at the connection F which, in FIG. 6, triggers the audible EEG. The table shows the components used in the figures. 
     The percent switch 24 of FIG. 1 has 20 positions. In passing through the first 10 of these positions it, first, connects the lead G of FIG. 6 to the leads L, M, N, O, P, Q, R, S, T, U of the counter Z26. For the eleventh through twentieth positions, it repeats the sequence. 
     For the first ten positions, the switch 24 leaves the lead H of FIG. 6 unconnected. For positions 11 to 19, the switch 24 connects the lead H to the lead V of the counter Z27. For the twentieth position, the lead H connects to the lead W.