JP3141013B2 - Activation brain wave monitoring method and activation brain wave monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and a device for monitoring an activated electroencephalogram.

[0002]

2. Description of the Related Art Conventionally, as an electrode arrangement of an electroencephalograph, FIG.
International electrode arrangement method (10-20 method) as shown in FIG.

FIGS. 5A to 5E show an electrode arrangement procedure viewed from the front upper surface of the head. First, (a) a nose root, ie, a median portion and an occipital pole on an anterior forehead suture line; 5A, the median line along the skull surface connecting the intersection of the line of the demarcation term of the occipital bone and the median sagittal plane is 10%, 20%, 20%, 20%, 20% as shown in FIG. 5A.
%, 10%, and FP _Z , F _Z ,
Let C _Z , P _Z , O _Z. (B) Crossing lines along the head surface passing through the C _Z point and connecting the left and right pre-auricular points (recesses at the root of the cheekbone in front of the tragus) are shown as 10%, 20%, and 20% as shown in FIG. 5B. %, 20%, 20%,
10%, T ₃ , C ₃ , C _Z , C ₄ , T
_{And 4} . (C) The total length of the coronal line connecting FP _Z and O _Z passing through T ₃ is 10%, 20%, 20%, 20%, 20%, as shown in FIG. 5C.
It is divided into 10%, and FP ₁ , F ₇ , T ₃ , T ₅ , and O _{1 in} the right hemisphere from FP _Z on the root side of the nose. (D) The total length of the inner coronal line passing through C ₃ and connecting FP ₁ and O ₁ is divided into four equal parts in the right hemisphere as shown in FIG. 5D, and these are defined as F ₃ , C ₃ , and P ₃ from the front. . (E) In the left hemisphere, by performing the same procedure as (c) and (d), FP ₂ , F ₈ , T ₄ , T ₆ , O ₂ and F ₄ ,
By setting C ₄ and P ₄ (see FIGS. 5C and D), electrodes were arranged at each point as shown in FIG. 5E, and the electroencephalogram measurement was performed.

In a clinical electroencephalography at the time of electroencephalogram measurement using such an electrode, hyperventilation activation (HyperVentilati) is performed.
on, hereafter referred to as HV). This activation method is 20 times per second more than the speed of breathing at rest.
Intense expiration ３０30 times, sustaining large breathing for 3 to 4 seconds, to induce an abnormal wave of petit mal.

[0005] In such an activation method using HV, a build-up causing an increase in the amplitude of the electroencephalogram and a slow wave occurs.
In p), a high-amplitude slow wave of 6 Hz or less is induced in the bilateral forehead during hyperventilation, and if it does not disappear 30 seconds after hyperventilation, or if it is further enhanced, cerebrovascular disorder or epileptic Abnormality is suspected.

[0006] Such a build-up phenomenon occurs when the concentration of carbon dioxide in the blood decreases and the pH of the blood tends to become alkaline.
It has been attributed to karosis, which results in contraction of peripheral blood vessels.

Also, a spike-slow wave complex of 3 Hz (3 Hz spi
ke and slow wavecomplex) are specifically induced in absence seizures, and it has been examined that this 3 Hz spike and slow wave complex appears widely for 20 to 60 seconds.

FIG. 7 shows an example of a measurement result of a build-up electroencephalogram by HV, in which electrodes are arranged at respective parts of the head by the 10-20 method shown in FIG. FIG. 7A shows the state before HV,
FIG. 7B shows an electroencephalogram waveform during HV, and FIG. 7C shows an electroencephalogram waveform at the end of HV.

[0009]

As described above, an HV which induces sudden abnormalities or non-sudden slow waves in clinical electroencephalography is recorded on a recording paper on a display device or a recording device as shown in FIG. Doctors made subjective judgments by directly observing the EEG waveform.

However, the comparison of the electroencephalogram waveforms during activation and before and after activation involves the electroencephalogram waveforms from channels from many electrodes, which not only complicates the comparison but also imposes objectivity on the subject, and further complicates the comparison with other subjects. Comparison is also difficult. Therefore, there has been a demand for a monitoring method that can objectively evaluate the determination of build-up in an HV and can compare the determination with other subjects.

An object of the present invention is to provide an activated electroencephalogram monitoring method capable of quantitatively and temporally monitoring changes during and after HV with a power spectrum based on an electroencephalogram waveform at rest before HV. It is intended to provide a device used for this.

[0012]

An activation electroencephalogram monitoring method according to the present invention extracts a predetermined frequency band component of a resting electroencephalogram before activation and calculates a power to calculate a power of a reference activation band component. a step ST _2, and extracting a predetermined frequency band component of the EEG at least activated during a current power value calculation step ST ₆ which calculates the power calculating a power of the current activation band component, the current power value of the current activation band components a relative value calculating step ST ₇ for calculating the relative value of the reference power value of the reference activation band component, and a step of calculating the activation index computed up rate with respect to the reference value from the relative value, the activation index variation At least during the activation and after the activation.

An activation electroencephalogram monitoring apparatus according to the present invention extracts a predetermined frequency band component of an electroencephalogram at rest before activation and calculates a power to calculate a power of a reference activation band component. Current power value calculating means for extracting a predetermined frequency band component of the brain wave at the time and calculating the power to calculate the power of the current activation band component, and the current power value of the current activation band component and the reference power of the reference activation band component A relative value calculating means for calculating a relative value of the value, and a step of calculating an activation index obtained by calculating an up rate with respect to a reference value from the relative value, wherein a change amount of the activation index is changed at least during activation and after activation. It is formed by displaying or recording in a typical manner.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An activated electroencephalogram monitoring method and apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a flowchart of an activated electroencephalogram monitor device showing an embodiment of the present invention, FIG. 2 is a system diagram of the activated electroencephalogram monitor device showing an embodiment of the present invention, FIG. 3 is an FFT analysis result diagram, and FIG. FIG. 5 is a waveform diagram quantified and displayed by the power spectrum at the time of HV displayed by the activated brain wave monitoring method according to the embodiment of the present invention, and FIG. 5 is a diagram illustrating an example of a display screen.

Before explaining the operation of the flowchart of FIG. 1, the activated electroencephalogram monitor of the present invention will be described with reference to FIG.

In FIG. 2, reference numeral 1 denotes a human head, and a plurality of electrode groups are arranged above the head by, for example, the 10-20 method described with reference to FIG.

The electroencephalogram measurement potentials from the plurality of electrode groups 2 are supplied to an analog-to-digital converter (ADC) 5 via an amplifier 3 and a multiplexer 4, and the digitized measurement potentials are supplied to a computer via an input port 6. Below CPU
9).

The CPU 9 has a control section and an operation section. An address bus and a data bus 12 are connected to a work RAM 10.
And the ROM 11, the input port 6, and the output port 13.

The input port 6 is connected to an operation unit 7 such as a keyboard and a mouse, and an external storage device 8 storing measured brain waveform data and the like.

The output port 13 is connected to a display device 14 such as a printer or a CRT for recording or displaying the calculation result of the CPU 9 and a recording device 15.

The operation of the above configuration will be described with reference to the flowchart of FIG. 1 and the display waveforms of FIGS.

The head 1 of the subject by arranging the electrode group 2, the electroencephalogram measurement of each part at rest as in the first step ST ₁ 1
Perform for about 0 seconds.

Next, the measurement electroencephalogram waveform at rest is decomposed into frequency components by a technique such as Fast Fourier Transform (FFT), and calculates the power value (power spectrum) as in the second step ST _2.

In the third step ST ₃ , the second step ST
_The power value obtained in ₂ is stored in a storage means such as the RAM 10 based on the power value. C in FIGS. 4 and 5 indicates a reference value.

In the fourth step ST ₄ , hyperventilation activation (H
V) is started. In general, 20 to 30 deep breaths (more expiration) per minute are performed for 3 to 4 minutes.

[0026] The fifth step ST ₅ In any electrode position during activation, specify the example _{F 3, F 4, C 3} , induction of such _{C 4, P 3, P 4} , captures the induction potential of the electroencephalogram waveform.

[0027] For example the sixth step ST ₆ HV, the frequency range is seen a buildup 2Hz~7Hz
Fast Fourier transform (FF) of nearby band components every 10 seconds
Perform frequency analysis using T). At this time, if a plurality of FFT analysis sections are required in the analysis section, the frequency elements may be added.

FIG. 3 shows the result of FFT analysis, in which the vertical axis indicates the power value, the horizontal axis indicates the frequency (Hz), and the frequency range from 2 Hz to 7 Hz where the build-up occurs is indicated by a bar 16 for easy understanding. it's shown. A waveform 17 (broken line) shows the power of the activation band frequency portion at rest before HV, and a waveform 18 (solid line) shows the current power value.

[0029] Based on the power of the reference value stored in the next storage unit in a seventh step ST _7, CPU 9 performs a relative value operation.

The relative value calculation in the seventh step ST ₇ is obtained by the following equation.

Further, in order to display a trend using the up ratio with respect to the reference value C as an index (activation index), a calculation for setting the relative value to zero is performed using two equations. Activation index = relative value−100 ‥‥ (2)

[0032] by performing calculation in this way, the operation result is stored in the 1 o'clock storage unit 10, a look at whether calculation end in the eighth step ST _8, the sixth step ST _6, if NO
If YES, the process proceeds to the ninth step ST ₉ , where the relative value (power value) is trend-displayed at the time of activation and for a predetermined time after activation, and the process ends.

FIG. 4 shows the activation index which is the relative value of the power or the percentage of change from the reference value on the vertical axis, and the time (seconds) on the horizontal axis is the bar 16 position indicated by HV and the hyperventilation start time. It is shown, in hyperventilation were labeled _{H 1, H 2, H 3} ‥‥ every minute. The bar position indicated by AHV indicates the end of hyperventilation,
After completion of hyperventilation in every minute is performed trend display of _{A 1, A 2, A 3} ‥‥ a predetermined time.

[0034] The power value of EEG trend graph 19 parts P ₃ position electrode in FIG. 4, 20 displaying the power values of EEG sites C ₄ position electrode.

FIG. 5 shows an embodiment of an electroencephalogram reproduction screen on a CRT. In FIG. 5, reference numeral 21 denotes FIG.
In each part electrode F _P1 of the electrode group 2 described, F _P2 is ‥‥, respectively to the front direction of the electrode of the head 1 from the upper side of the screen, 22
Shows the EEG waveform of each channel induced from these electrodes.

The trend display described with reference to FIGS. 3 and 4 of the present invention is window-displayed on the electroencephalogram waveform screen as shown in FIG.

Reference numeral 23 denotes a frequency analysis graph (FFT) of an electroencephalogram waveform of the electrode designated by a predetermined lead every 10 seconds as in FIG.
24 is a graph showing a power trend similar to that of FIG.

As described above, according to the present invention, the activation band component is extracted by frequency analysis, the relative value based on the band component at rest before activation is calculated, and the horizontal axis is used to capture the temporal change. Since the time is displayed as a trend, the rate of change is concretely elucidated, and it could not be elucidated by analysis in the past, for example, when hyperventilation started, at what point the buildup started, and how much The point at which the brain wave returned to the state before the activation after the activation was clearly described.
FIG. 4 shows the hyperventilation monitor pattern. In this analysis, the recovery time of many cases took 1 minute or more. Probably, it was presumed in the inspection judgment that a return of about 30% from the baseline (line C) was determined to be a return. In addition, the appearance of sudden waves and falling asleep during the analysis were also observed. In cases with localized findings, comparison between the localized site and its symmetrical site was also clinically useful. In the monitoring method of the present invention, the frequency band and the lead to be analyzed can be arbitrarily selected. Therefore, it is conceivable to use a relaxation experiment using an alpha wave as an index, a sleep onset repetition measurement test, an optical drive monitor, or the like. In addition, a plurality of target channels can be used to compare, for example, the left-right difference between left and right brain waves. Since the present invention is configured as described above, the components are quantified by frequency analysis, so that the activation state of hyperventilation can be objectively grasped.

Further, since the power value is displayed as a time change as a trend graph, it becomes easy to understand the comparison with the value before the activation and the disappearance of the build-up after the activation is completed.

Furthermore, since the change in the relative value based on the state at rest before activation is displayed as a trend graph, comparison can be made without considering individual differences.

In the above-described configuration and method, the case where the brain wave waveform is converted into a trend graph in real time has been described. However, the display or recording may be performed using the brain wave waveform stored in the external storage means 8. it is obvious.

[0042]

The first effect of the present invention is that the activated state of hyperventilation can be objectively grasped. The second effect is that the comparison with the state before the activation and the disappearance after the end of the activation are clarified. The third effect is that comparisons can be made without considering individual differences.

[Brief description of the drawings]

FIG. 1 is a flowchart of the activation electroencephalogram monitoring device of the present invention.

FIG. 2 is a system diagram of an activated electroencephalogram monitor device of the present invention.

FIG. 3 is a graph showing an analysis result of FFT used in the activated electroencephalogram monitoring apparatus of the present invention.

FIG. 4 is a hyperventilation trend graph for two channels of an electroencephalogram of the activated electroencephalogram monitor device of the present invention.

FIG. 5 is an electroencephalogram reproduction screen of the hyperventilation monitor of the activated electroencephalogram monitor device of the present invention.

FIG. 6 is an electrode arrangement diagram showing a procedure of the international electrode arrangement method.

FIG. 7 is an electroencephalogram waveform chart at the time of conventional build-up.

[Explanation of symbols]

2 electrode group, 3 amplifier, 8 external storage device, 9
{CPU, 14} Display device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noboru Oki 3-42-6 Hongo, Bunkyo-ku, Tokyo NTT Medical Systems Corporation In-house (56) References JP-A-1-218429 (JP, A) JP-A-1-218430 (JP, A) JP-A-59-222130 (JP, A) JP-A-2-193645 (JP, A) JP-B 7-79809 (JP, B2) JP-B 47-48755 ( JP, B1) JP-T-63-500435 (JP, A) JP-T-58-500933 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5/0484

Claims (3)

(57) [Claims] 1. A reference power value calculation step of extracting a predetermined frequency band component of a resting brain wave before activation and calculating a power to calculate a power of a reference activation band component, at least a predetermined frequency band of the brain wave at the time of activation. Extracting a component, calculating power, and calculating the power of the current activation band component, and calculating a relative value between the current power value of the current activation band component and the reference power value of the reference activation band component. The relative value calculation step, and the up ratio with respect to the reference value was calculated from the relative value.
Calculating an activation index, wherein the amount of change in the activation index is displayed or recorded over time at least during activation and after activation. 2. A reference power value calculating means for extracting a predetermined frequency band component of a brain wave at rest before activation and calculating a power to calculate a power of a reference activation band component, and at least a predetermined frequency of the brain wave at the time of activation. Current power value calculating means for extracting a band component and calculating power to calculate the power of the currently activated band component; and calculating a relative value between the current power value of the current activated band component and the reference power value of the reference activated band component. A relative value calculating means for calculating, and an up ratio with respect to the reference value are calculated from the relative value.
Calculating an activation index, wherein the amount of change in the activation index is displayed or recorded over time at least during and after activation. 3. The activation index indicating the rate of increase with respect to the reference value is shown on the vertical axis as a value obtained by subtracting 100 from the relative value, and the activation start and activation end markers are displayed or displayed on the horizontal axis displayed over time. The method according to claim 1, wherein the method is performed by recording.