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

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.