Article

Dynamic statistical parametric mapping for analyzing ictal magnetoencephalographic spikes in patients with intractable frontal lobe epilepsy

Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Epilepsy research (Impact Factor: 2.19). 05/2009; 85(2-3):279-86. DOI: 10.1016/j.eplepsyres.2009.03.023
Source: PubMed

ABSTRACT The purpose of this study is to assess the clinical value of spatiotemporal source analysis for analyzing ictal magnetoencephalography (MEG). Ictal MEG and simultaneous scalp EEG was recorded in five patients with medically intractable frontal lobe epilepsy. Dynamic statistical parametric maps (dSPMs) were calculated at the peak of early ictal spikes for the purpose of estimating the spatiotemporal cortical source distribution. DSPM solutions were mapped onto a cortical surface, which was derived from each patient's MRI. Equivalent current dipoles (ECDs) were calculated using a single-dipole model for comparison with dSPMs. In all patients, dSPMs tended to have a localized activation, consistent with the clinically determined ictal onset zone, whereas most ECDs were considered to be inappropriate sources according to their goodness-of-fit values. Analyzing ictal MEG spikes by using dSPMs may provide useful information in presurgical evaluation of epilepsy.

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    • "Single dipole method sometimes does not provide adequate sources at the early latency as described above (Kanamori et al., 2013), whereas distributed source analysis provides reliable source distribution which can reconstruct the original, small signals of spikes at the sensor level. This ability is also useful for analyzing ictal MEG, which shows only small discharges in the early phase of seizures (Tanaka et al., 2009a). Distributed source analysis has nicely shown the possible onset of spikes with widespread cortical involvement at the peak in the previous studies (Shiraishi et al., 2005a,b; Kanamori et al., 2013). "
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    ABSTRACT: Magnetoencephalography (MEG), which acquires neuromagnetic fields in the brain, is a useful diagnostic tool in presurgical evaluation of epilepsy. Previous studies have shown that MEG affects the planning intracranial electroencephalography placement and correlates with surgical outcomes by using a single dipole model. Spatiotemporal source analysis using distributed source models is an advanced method for analyzing MEG, and has been recently introduced for analyzing epileptic spikes. It has advantages over the conventional single dipole analysis for obtaining accurate sources and understanding the propagation of epileptic spikes. In this article, we review the source analysis methods, describe the techniques of the distributed source analysis, interpretation of source distribution maps, and discuss the benefits and feasibility of this method in evaluation of epilepsy.
    Frontiers in Human Neuroscience 02/2014; 8:62. DOI:10.3389/fnhum.2014.00062 · 2.90 Impact Factor
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    • "maps represent the cortical activation derived by the spikes both spatially and temporally with distributed sources. Methodological details of spike analysis and MNE are described in the previous studies (Tanaka et al., 2009, 2010). "
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    Epilepsy research 11/2013; 108(2). DOI:10.1016/j.eplepsyres.2013.11.006 · 2.19 Impact Factor
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    • "For each subject, a regular grid-based mesh (∼400,000 nodes, ∼450,000 linear elements, ∼2 mm average edge length) was created and the so-called forward matrix (the values of the electric potential at each sensor due to every cortical source) was computed [18]. The inverse localization technique employed has been widely used for the study of epilepsy [20] [21] [22] and its technical details have been comprehensively explored elsewhere [23] [24], particularly in our previous publication [25]. Briefly, source localization is performed using a minimum-norm inverse linear operator [26] which seeks to minimize the expected difference between the estimated and the true inverse solution. "
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