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Electroencephalographic method and system for the quantitative description of patient brain states

  • US 4,201,224 A
  • Filed: 12/29/1978
  • Issued: 05/06/1980
  • Est. Priority Date: 12/29/1978
  • Status: Expired due to Term
First Claim
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1. The method of determining the brain state of a patient including the steps of:

  • (a) attaching a plurality of electrodes to the scalp of a comatose patient or a patient with other brain dysfunctions to detect the patient'"'"'s brainwaves in the form of electroencephalographic (EEG) and evoked response (EP) data;

    (b) amplifying the electrical signals detected at each electrode;

    (c) using a programmed computer based system as the control for stimulating the patient with a series of multi-sensory stimulations to elicit evoked responses from cortex and brain stem;

    (d) obtaining and analyzing on-line digital EEG or EP data by connecting analog-digital converters to each amplifier, and digitizing all data as it is gathered;

    (e) obtaining sets of on-going EEG and average evoked response data for the patient and using said computer based system to extract diagnostically useful features from such sets of data, and automatic construction of a Z-transform for each such feature based upon a comparison with stored normative data obtained by computing mean values and standard deviations for each feature from groups of subjects or patients without head trauma or brain dysfunction;

    (f) computing a state vector for the patient comprising a vector sum based upon those Z-transformed features which are significantly deviant from normative values; and

    (g) visually displaying the length (severity), orientation (quality) and change with time of said state vector.

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