Dynamical analysis of epileptic characteristics based on recurrence quantification of SEEG recordings

The evolution of epilepsy is always accompanied with the transitions of dynamics. Characterizing these dynamical processes can be beneficial for understanding the mechanism of seizures. Meanwhile, there also exist dynamical differences between regions, especially in the epileptogenic and non-epileptogenic areas. Hence, in this study stereo-electroencephalograph (SEEG) recordings from 10 patients with refractory focal epilepsy were collected, and recurrence plot was used to investigate the dynamical differences between different epilepsy stages as well as regions. All dynamical characteristics were quantified by means of recurrence quantification analysis. Furthermore, synchronization between channels were also revealed through cross recurrence plot. Results suggested that almost all channels in the pre-ictal and ictal stages had higher recurrence rate than those in the inter-ictal. And epileptogenic channels were identified with longer diagonal structures, which indicated that recordings from epileptogenic regions were more deterministic and recurrent. When seizures occurred, the synchronizations between these epileptogenic channels were strengthened and dominated the dynamics of epileptic brain. This might provide additional insights into the dynamical nature of epileptic phenomena.