Nonlinear dynamic analysis of scalp EEG epileptic signals.

S. BLANCO; J. CRESO; A. FIGLIOLA; R. QUIAN QUIROGA; O. A. ROSSO

Instabilities and Nonequilibrium Structures VII & VIII.

Kluwer Academic Publishers

Lugar: Dordrecht, Netherlands; Año: 2004; p. 149 - 157

Noisy signals obtained during a tonic-clonic epileptic seizure, are usually neglected for visual inspection by the physicians due to the presence of muscle artifacts. Although noise obscures completely the recording, information about the underlying brain activity can be obtained by filtering, through the Orthogonal Wavelet Transforms, those frequencies bands associated with muscle activity. After generating a ``noise free" signal by removing the muscle artifacts with wavelets, a dynamical analysis of the brain behavior will be performed by using nonlinear dynamics methods. The values for nonlinear metric invariants, like the correlation dimension and the maximum Lyapunov exponent, confirm that the brain dynamical behavior is more ordered during the epileptic seizure than  pre-seizure stage.