Magnetoencepharographic analyses by spatial filtering for child patients with epilepsy

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One hundred nine patients underwent magnetoencephalographic (MEG) study. MEG data were collected by 306ch helmet-shape gradiometers (Vector View System, Neuromag Oy Stockholm, Sweden) with 600 Hz sampling rate at Hokkaido University Hospital.According to classification of epileptic types and syndromes by International League against Epilepsy (1987), subjective patients were classified as following: 85 cases with symptomatic localization related epilepsy (SLRE), 15 cases with idiopathic localization related epilepsy (ILRE), 2 cases with symptomatic generalized epilepsy (SGE) and 2 cases with idiopathic generalized epilepsy (IGE).Conventional single dipole analysis could solve the data sets of 83 cases (65 cases with SLRE, 12 cases with ILRE, 3 cases with SGE, a case with IGE, 2 cases with UDE) with significant clustering of equivalent current dipoles in a specific gyrus in cerebral cortex, and with confirmation in their seizure manifestation and other electro-clinical findings.Then we u … More sed spatial filtering analysis: dynamic statistical parametric mapping (dSPM) for the rest of cases and 16 cases (10 cases with SLRE, 3 cases with ILRE, 2 cases with SGE, a case with IGE) with multi-focal or widespread epileptiform activities could be evaluated reasonably as multi-focal or widespread distribution of MEG activities.Finally we applied time frequency analysis: short time Fourier transforms (SFT) for remaining 10 cases with low amplitude rhythmic magnetoencephalographic epileptiform activities and it showed the significant epileptogenic area, since the distribution of rhythmic activities were well correlated to the demonstration of ictal onset area.By means of single dipole analysis, spatial filtering analysis: dSPM and time-frequency analysis: SFT successfully demonstrated the distribution of the epileptogenic area in patients with epilepsy MEG analysis was supposed to be useful for almost every patient with epilepsy for presurgical evaluation or the diagnosis of the epileptic syndromes. Less