Wavelet analysis of generalized tonic-clonic epileptic seizures

O. A. ROSSO; S. BLANCO; A. RABINOWICZ

SIGNAL PROCESSING

Elsevier Science

Año: 2003 vol. 83 p. 1275 - 1289

0165-1684

The analysis of generalized tonic-clonic seizures is usually di0cult with quantitative EEG techniques due to muscle artifact. We applied two quanti4ers based on the Wavelet Transform to evaluate 20 seizures from eight consecutive patients admitted for video-EEG monitoring. We studied the relative wavelet energyand the wavelet entropyover time. In 16/20 events we found signi4cant decremental activityin the relative wavelet energyassociated with frequencyband 0.8–3:2 Hz (delta activity) at the seizure onset, indicating that the seizure is dominated bymedium frequencybands 3.2–12:8 Hz (theta and alpha bands). In 19/20 events the mean wavelet entropypresents lower values during the ictal period compared to the pre-ictal period, indicating that the associated dynamic is more ordered and simple. Thus the employed tools show good accuracy for detecting changes in the system dynamic. We conclude that this behavior could be induced by frequency tuning in the neuronal activitytriggered byan hypothetic epileptic focus.16/20 events we found signi4cant decremental activityin the relative wavelet energyassociated with frequencyband 0.8–3:2 Hz (delta activity) at the seizure onset, indicating that the seizure is dominated bymedium frequencybands 3.2–12:8 Hz (theta and alpha bands). In 19/20 events the mean wavelet entropypresents lower values during the ictal period compared to the pre-ictal period, indicating that the associated dynamic is more ordered and simple. Thus the employed tools show good accuracy for detecting changes in the system dynamic. We conclude that this behavior could be induced by frequency tuning in the neuronal activitytriggered byan hypothetic epileptic focus.