Independent component analysis of generalized spike-and-wave discharges: primary versus secondary bilateral synchrony.
OBJECTIVE
To differentiate between primary and secondary bilateral synchrony (PBS and SBS, respectively) in generalized spike-and-wave discharges (GSWD), we applied independent component analysis (ICA) to GSWD, and analyzed the characteristic patterns of independent components.


METHODS
EEGs from 19 patients with GSWD (9 PBS patients, 10 SBS patients) were studied. Thirty GSWD epochs were selected and concatenated to construct an EEG data matrix that was subjected to ICA. Selected independent components were localized by mapping them on a spherical model of the head by means of brain electrical source analysis (BESA) to define dipole sources.


RESULTS
Epileptic components of GSWD were clearly separated by the ICA algorithm in all patients. Between one and three components per patient were responsible for GSWD. In PBS patients, 70.6% of the independent components had dipole sources within the dorsolateral frontal region, and 56.5% of the independent components in SBS patients were within the medial frontal region (P=0.012). The orientation of all of the independent components in PBS patients was radial, whereas 47.8% of the independent components in SBS patients were tangential; this difference was statistically significant (P=0.001).


CONCLUSIONS
Spatiotemporal decomposition of GSWD by using ICA might be helpful for differentiating SBS from PBS.


CONCLUSIONS
The localization of the dipole sources of the independent components may provide insight into the pathophysiological origins of GSWD.
Jung
Ki-Young
KY
Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710, South Korea. kyjung@smc.samsung.co.kr
Kim
Jae-Moon
JM
Kim
Dong Wook
DW
Chung
Chin-Sang
CS
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D003344:Cortical Synchronization / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male