| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Benign childhood epilepsy with centrotemporal spikes (BCECS) is a well-described entity (Lombroso, 1967). Interictal EEG shows normal base rhythms with characteristic centrotemporal spikes, namely rolandic discharge (RD). The most prominent element of RD is a negative sharp wave with a following positive wave whose amplitude is frequently up to 50% of that of the preceding negative sharp wave (Luders, 1986).
Althougha voltage gradient study (Lombroso, 1967), topographical analysis of EEG (Gregory, 1984), and electrical dipole localization analysis of RD (Wong, 1989) have been reported previously, the generator and propagation of RD in the brain remained unclear. In this study, RD and somatosensory evoked magnetic field (SEF) in BCECS were closely analyzed using 37-channel magnetoencephalography (MEG) with three-dimensional dipole neuromagnetic localization.
Seven patients with BCECS and 10 patients with other epilepsy were studied at the outpatient clinc of Kyushu University Hospital. In
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formed consent was obtained from each patient and their parents. MEG was performed in a magnetically shielded room using a 37-channel first order gradiometer system (Magnes^R ; Biomagnetic Technologies Inc., San Diego, CA). EEG was simultaneously performed according to the international 10-20 system via the external input channels of the Magnes system. Time series wave form data were visually evaluated and single equivalent dipole source localization calculations were performed over selected artifact-free segments of the data corresponding to RD events (Morioka, 1994 ; Ogashiwa, 1992).
The contralateral thumb, little finger, and lower lip, to the RD appearance side, were mechanically stimulated. By means of high-pressure air (5 kg/cm^2), tapping stimulation was delivered. The cortical response of SEF was recorded by the same methods as mentioned above (Morioka, 1994).
Dipoles of the prominent negative sharp waves of RD appeared as tangential dipoles in the rolandic region with positive poles sitated anteriorly. Negative sharp waves showed a relatively limited localization and regular directions compared with other components. Dipoles of the positive waves following negative sharp waves appeared in the vicinity of negative sharp waves. Dipoles of the SEF stimulated at the lower lip were located in the same gyrus from which the prominent sharp negative waves of RD originated. Magnetic fields strength were compared between BCECS patients group and other epileptic patients group. Responses of the BCECS were three times higher than those of other patients group. These findings suggested that RD are basically generated through the same or a similar mechanism to that of the late components of somatosensory evoked responses. Less
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