Nonlinear EEG analysis in epilepsy: Its possible use for interictal focus localization, seizure anticipation, and prevention

Several recent studies emphasize the high value of nonlinear EEG analysis
particularly for improved characterization of epileptic brain states. In this review the
authors report their work to increase insight into the spatial and temporal dynamics of
the epileptogenic process. Specifically, they discuss possibilities for seizure anticipation,
which is one of the most challenging aspects of epileptology. Although there are
numerous studies exploring basic neuronal mechanisms that are likely to be associated
with seizures, to date no definite information is available regarding how, when, or why
a seizure occurs. Nonlinear EEG analysis now provides strong evidence that the
interictal-ictal state transition is not an abrupt phenomenon. Rather, findings indicate
that it is indeed possible to detect a preseizure phase. The unequivocal definition of
such a state with a sufficient length would enable investigations of basic mechanisms
leading to seizure initiation in humans, and development of adequate seizure prevention
strategies. Key Words: Epilepsy--Interictal state--Preictal state--Seizure anticipation--
Seizure prevention--Focus localization--Nonlinear time series analysis--
EEG.