INTERICTAL SPIKE DIPOLE CLUSTER ANALYSIS IN HYPOTHALAMIC HAMARTOMA EPILEPSY
Abstract number :
2.157
Submission category :
Year :
2003
Submission ID :
2255
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
José M. Fernandes, Alberto J.R. Leal, Jo[atilde]o Paulo S. Cunha Department of Electronic and Telecommunications and IEETA, University of Aveiro, Aveiro, Portugal; Department of Clinical Neurophysiology, Hospital J[uacute]lio de Matos, Lisbon, Portugal; D
The epilepsy associated with hypothalamic hamartomas constitutes a syndrome with peculiar seizures usually refractory to medical therapy, mild cognitive delay, behavioural problems and multifocal spike activity in the scalp electroencephalogram (EEG). Recently we demonstrated that there is a consistent origin of spike activity in the subcortical region in the neighbourhood of the hamartoma, with late spread to cortical areas. Our objective is to complement the characterization of spike activity origin and spread through the source analysis complemented with statistical spatio-temporal filtering.
For 4 patients suffering from epileptic syndrome due to hypothalamic hamartomas where the localization of epileptogenic activity is well described, we performed source analysis (moving dipole model using Marquardt method) of interictal spikes using 1) the average spike source analysis (ASSA) and 2) the characterization of clouds of individual sources (CIS) of isolated epileptogenic events. For the average patterns a further study was conducted using Rap-MUSIC algorithm in order to discriminate all possible sources.
The CIS were characterized by one or more visually independent and dense clusters - depending on the patient. The clusters identified areas coincident with the sources identified using the Rap-MUSIC method, which was not the case of all the considered average spike patterns use in ASSA.
The clouds of dipoles associated to individual interictal spikes brought an increase of information against common ASSA, not only on the localization (in agreement with the sources identified in Rap-MUSIC), but also due to the dense areas of activation (as clusters of dipoles).
The results indicate that the CIS may be a useful and less demanding approach in source analysis: 1) does not imply spike clustering, 2) provides richer spatial information on the activation area.
The results suggest that study of the spatio temporal structure of the clusters of dipoles may provide an insight in the propagation patterns of the epileptiform activity. This is our current line of work.
[Supported by: Funded by project [quot]Topo3D[quot] (POSI/CPS/39758/2001) of the [quot]Funda[ccedil][atilde]o para a Ci[ecirc]ncia e Tecnologia[quot], Portugal]