Abstract
A new computer system to detect stationary potential (SP) changes of the brain and to display an isopotential chart of SP was developed. The system was named computerized stationary potential encephalography (C-SPEG).
The advantage of this new technique is that it can be operated as easily as routine EEG recording, and it is possible not only to ascertain the distribution of SP, but also to display a topographical map of each spectral band of EEG, namely, delta, theta, alpha and beta.
The device consists of 18 Ag/AgCl electrodes, an input box, a SP detector, an electroencephalograph, a data recorder controller, a mini-computer (Nihon Kohden ATAC-2300), a magnetic disc and a serial printer for display.
One hundred and forty cases were evaluated by C-SPEG. The technique allowed topographical diagnosis in 80 out of 95 cases (84%), whereas EEG did so only in 45 out of 95 (47%). The difference is statistically significant (P<0.001). The operation of this system was similar to the formerly developed SPEG, which had 90 calomel half-cell electrodes.
Four cases are presented to illustrate the advantages of C-SPEG.
The most unique point of C-SPEG is that it elucidates the relationship between the lesion and the cerebral cortex on the basis of polarity of SP change: “negative” corresponds to cortical damage, “positive” to subcortical damage, and “crateriform” to expanding mass to the cortex. Thus, C-SPEG potentiates the diagnostic ability of computerized tomography (CT).
