Dynamics of frequency flow in epileptic brain during extra-temporal partial and idiopathic generalized epilepsy

Temporal lobe epilepsy has been known to be associated with buildup of 4-7 Hz activity preceded by attenuation near the seizure focus. Using a wavelet based algorithm, we recently showed that for the patients with temporal lobe epilepsy, frequency flow on the scalp EEG builds up to 5-12 Hz range just prior to and during the initial stages of the seizure. Here we present frequency flow analysis on EEG of patients with extra-temporal partial epilepsy and patients with idiopathic generalized epilepsy (IGE) to investigate any characteristic frequency flow patterns in these patients. We found that frequency flow in these patients also stays sustained in the 5-12 Hz range for longer periods of time just prior to and during the initial stages of the seizure compared to their respective baseline interictal recordings. The 5-12 Hz frequency flow was seen uniformly in all the channels in patients with IGE although it was seen most prominently adjacent to the seizure focus and to a lesser extent in other channels in patients with partial epilepsy.