[Spectral and integral-temporal analysis of cerebral evoked potentials in epilepsy patients]

Changes in the spectral and integral-temporal characteristics of evoked potentials (EP) to flashes, were studied in 17 epileptic patients and 20 normals. The analysis of EP was done on a background recording and after a 2-minute hyperventilation. It was demonstrated that an epileptization of the brain according to the integral indices of EP is expressed by an increase in the square response, duration of EP (an increase in the duration of the system return to a state of equilibrium), by a higher level of residual noise in a discharge of EP, as well as by an increase in the negative part of EP and a larger instability of responses. The spectral content of EP in epileptic patients demonstrates an increase in amplitude maxima, especially within theta = psi delta ranges. Hyperventilation in epileptic patients evokes a pronounced synchronization of brain bioelectric activity, which leads to a drop of the response intensity and an increase in the level of residual noise in a discharge of EP. The data obtained suggest that the proposed method of EP analysis may be effective in the determination of the intensity in the focus of epileptical activity, as well as in the study of the function of inhibitory mechanisms of convulsive discharges.