TEMPORAL LOBE EPILEPSY: LOCALIZATION OF EPILEPTOGENIC ZONE BY WAVELET ENTROPY IN EEG SCALP SIGNALS
Abstract number :
2.152
Submission category :
Year :
2003
Submission ID :
3659
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Giagante Brenda, Rosso Osvaldo, Silva Walter, Legnani Walter, Consalvo Damian, Oddo Silvia, D. Atellis Carlos, Kochen Silvia Centro de Epilepsia. Division Neurologia, Htal Ramos Mejia, Buenos Aires, Buenos Aires, Argentina; Instituto de Biologia Celular y
The processing of information by the brain is reflected in dynamical changes of the electrical activity in time, frequency, and space. Therefore, the concomitant studies require methods capable of describing the qualitative variation of the signal in both time and frequency. Here we present a quantitative EEG method based on the Orthogonal Discrete Wavelet Transform (ODWT) of the EEG signal.
The normalized Total Wavelet Entropy (NTWS) is a measure of the order/disorder degree in the EEG signal. This quantifier is computing on scalp EEG signals of epileptic patients with mesial temporal epilepsy lobe (MTLE). We analyzed dynamical changes of the electrical activity in time, frequency, and space through out the NTWS.
We analyzed 10 seizures in 5 patients with MTLE that underwent anterior temporal lobectomy and had an excellent outcome. The time evolution for the NTWS from preictal and ictal scalp EEG was analyzed in time windows without overlap of 1.28 seconds. The epileptogenic zone was determined by a strong decrease (40-60%) of the entropy with respect to the background level in the channels that were involved at seizure onset. The mean NTWS presents lower values during the ictal period compared to the background EEG, indicating that the associated dynamic is more ordered and simple.
The NTWS seemed to be a very useful quantifier tool that contributes to the determination of the epileptogenic zone in MTLE.
[Supported by: UBA. CONICET. CEFYBO]