Dipole Analysis Using Averaging Method: Comparison between Benign Epilepsy with Centrotemporal Spikes and Intractable Extratemporal Lobe Epilepsy.
Abstract number :
2.215
Submission category :
Year :
2001
Submission ID :
286
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
S. Chitoku, MD, Pediatrics, The hospital for Sick Children, Toronto, ON, Canada; H. Otsubo, MD, Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada; A. Ochi, MD, Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada; A. Shirasawa, Ne
RATIONALE: Averaging method is used for dipole analysis to improve signal to noise ratio in benign epilepsy with centrotemporal spikes (BECTS). On the other hand, it is known that averaging spikes do not always provide appropriate dipole with high Goodness of fit (GOF) in extratemporal lobe epilepsy (ETLE). We compared these two groups for their clustering results of individual spikes and results of dipole analysis using averaged spikes.
METHODS: Five patients with BECTS (group A: one boy and four girls, age ranging 6-12 years), and five patients with intractable ETLE (group B: two boys and three girls, age ranging 5.5-15 years) were studied. All the patients in group B underwent subdural EEG recording for detect their epileptic zone. Individual spikes were automatically detected and clustered. After the clustering, one representative spike group was selected and averaging was performed at the center of the maximum negative peak electrode. Averaged spike was analyzed using single dipole method with 3 shell spherical head model. Results of clustering and dipole analysis were compared between two groups. In group B, dipole locations were compared with the epileptic zone determined by subdural EEG recording.
RESULTS: Group A showed less clustered groups and larger numbers of spikes in the selected group than those of group B. Dipole analysis in group A resulted in greater numbers of time points with high GOF than in group B. More condensed dipole localizations were seen in group A. Group A showed stable dipoles, while group B showed moving dipoles. Four out of five patients in group B presented with inconsistent localized dipoles within the epileptic zone.
CONCLUSIONS: Averaging method is useful for dipole source localization in the epilepsy that has consistent individual spikes.