Digital electroencephalographic instrument and method

• US 4,417,592 A
• Filed: 05/11/1981
• Issued: 11/29/1983
• Est. Priority Date: 05/11/1981
• Status: Expired due to Term

• Current Assignee: New York University
• Original Assignee: John E. Roy
• Inventors: John, E. Roy
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US06/262,395
• Time in Patent Office: 932 Days
• Field of Search: 128/731-732, 128/733, 128/710, 128/712, 346/33 HE
• US Class Current: 600/544
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16

Abstract

An electroencephalographic (EEG) system includes an electroencephalographic instrument comprising a plurality of electrodes adapted to be removably connected to the patient'"'"'s head to detect brain waves; a plurality of amplifiers, with each amplifier connected to a pair of electrodes; an output multiplexer and a multi-line electrographic recording device, such as a matrix printer, whose display is an on-line display of multi-channel simultaneous wavy lines on a recording medium, such as a strip chart. A digital signal conditioning system is connected between the outputs of the amplifiers and the input of the recording device and functions to minimize misleading effects of muscular artifacts, to detect epileptiform spikes and sharp waves, and to perform quantitative analysis of the EEG signals. This signal conditioning system includes a comparison means which compares analytical features of the patient'"'"'s brain waves on a statistical basis, with norms stored in a digital storage means. These features are extracted from the EEG by spectral analysis, coherence analysis and symmetry analysis. Other modular digital systems and software may be added to compute cortical and brainstem average evoked potentials using multimodal sensory stimuli, to extract diagnostic features from the average evoked potentials (EP'"'"'s) by computing algorithms, to construct graphic and alphanumeric displays, or to write an analytic diagnostic report.

Claims

1. An electroencephalographic system for the on-line conditioning of signals representing brain waves and representing muscle artifact, comprising a plurality of electrodes adapted to be removably attached to the head of a patient, a plurality of amplifiers each connected to a different pair of said electrodes, a matrix multi-channel display and recorder which in response to digital signals displays a copy of a plurality of the brain wave signals simultaneously in the form of a plurality of visible wavy lines on a recording surface, each wavy line being a series of dots which is the record of a different pair of said electrodes;

a digital signal conditioning means connected between said amplifiers and said multi-line channel dispay and recorder to reduce the adverse effects of said muscle artifact signals, said digital signal conditioning means including;

A/D means to convert the analog signals from each of said amplifiers into digital signals representing samples of the patient'"'"'s brain waves;

digital data storage means for the containing of brain wave norms;

digital comparison means to compare said brain waves with brain wave norms in said data storage means;

said comparison means including means to compare the samples of the patient'"'"'s brain waves with a norm for the amplitude of the sample stored in said storage means, means to detect said samples representing brain waves at a selected level above said norm, means to detect said samples representing brain waves at a selected level below said norm and means to analyze said samples for spikes and sharp waves;

connection means to connect said A/D means, digital data storage means and comparison means to provide said signal conditioning;

multiplexer means connected to said digital signal conditioning means and said recorder to distribute digital data from said digital signal conditioning means to the various channels of the recorder so that artifact-free brain waves and the said spikes and sharp waves are recorded by said recorder.

2. An electroencephalographic system as in claim 1 wherein the A/D means is a variable gain multiplexed analog-digital converter.

3. An electroencephalographic system as in claim 1 and further including electrodes adapted to be connected to the patent'"'"'s temporal muscle and neck muscles for artifact detection;

electro-oculogram (EOG) and electro-myogram (EMG) detectors and amplifiers connected to said temporal and neck electrodes for producing

the electro-oculograms and electro-myograms of the patient;

means connecting said EOG and EMG amplifiers to said A/D means; and

means to detect and analyze the said electro-oculograms (EOG) and electromyograms (EMG) of the patient.

4. An electroencephalographic system as in claim 1 and further including, as an additional portion of said conditioning means:

means to generate the spectral analysis, coherence analysis and symmetry analysis of the said brain waves; and

means for computing the Z-transforms of the said spectral, coherence and symmetry analysis compared to stored norms.

5. An electroencephalographic system as in claim 4 and further including:

means to automatically generate a report stating said Z-transforms.

6. An electroencephalographic system as in claim 1 wherein said data storage means includes magnetic floppy disks.

7. A method in electroencephalography for the on-line conditioning of signals representing brain waves, including the steps of removably attaching a plurality of electrodes to the head of a patient to detect signals representing the brain waves and muscle artifact of the patient, connecting a plurality of amplifiers with each amplifier being connected to a different pair of said electrodes, producing an on-line copy of the brain wave signals on a matrix multi-channel display and recorder which is responsive to digital signals, the display of the brain wave signals from each different pair of the said electrodes being a visible wavy line composed of a series of dots and being simultaneously displayed and recorded with the brain wave signals from other pairs of said electrodes;

comprising connecting a means for digital signal conditioning between said amplifiers and said recorder said means reducing the adverse effects of said muscle artifact signals said digital signal conditioning including;

converting the analog signals from each of said amplifiers into digital signals representing samples of the patient'"'"'s brain waves using A/D means;

storing brain wave norms in a digital data storage means; and

comparing said brain waves with brain wave norms in said data storage means using digital comparison means;

said comparing including comparing the samples of the patient'"'"'s brain waves with a norm for the amplitude of the sample stored in said storage means, detecting said samples representing brain waves at a selected level above said norm, detecting said samples representing brain waves at a selected level below said norm and analyzing said samples for spikes and sharp waves; and

connecting multiplexer means to said digital signal conditioning means and said recorder and distributing digital data from said digital signal conditioning means to the various channels of the recorder so that artifact-free brain waves and the said spikes and sharp waves re recorded by said recorder.

8. An electroencephalographic method as in claim 7 wherein the said conversion into digital signals is accomplished by varying the gain of a multiplexed analog-digital converter.

9. An electroencephalographic method as in claim 7 and further including attaching electrodes to the patient'"'"'s temporal muscle and neck muscles for artifact detection;

connecting EOG and EMG amplifiers to said temporal and neck electrodes to produce electro-oculograms (EOG) and electromyograms (EMG) of the patient;

connecting analysis means to said EOG and EMG amplifiers to detect and analyze the said electro-oculograms (EOG) and electromyograms (EMG) and displaying said EOG and EMG analysis on said matrix display.

10. An electroencephalographic method as in claim 9 and further including, as an additional step of said signal conditioning;

performing spectral, coherence and symmetry analysis on the basis of comparisons to said stored norms, and generating the Z-transforms of the said spectral, coherence and symmetry analysis.

11. An electroencephalographic method as in claim 10 and further including the step of:

automatically generating a report stating said Z-transforms.

12. An electroencephalographic method as in claim 7 wherein said storing is by data input onto flopy disks.