Regional differences in the sensitivity of MEG for interictal spikes in epilepsy.
MEG interictal spikes as recorded in epilepsy patients are a reflection of intracranial interictal activity. This study investigates the relationship between the estimated sources of MEG spikes and the location, distribution and size of interictal spikes in the invasive ECoG of a group of 38 epilepsy patients that are monitored for pre-surgical evaluation. An amplitude/surface area measure is defined to quantify and rank ECoG spikes. It is found that all MEG spikes are associated with an ECoG spike that is among the three highest ranked in a patient. Among the different brain regions considered, the fronto-orbital, inter-hemispheric, tempero-lateral and central regions stand out. In an accompanying simulation study it is shown that for hypothesized extended sources of larger sizes, as suggested by the data, source location, orientation and curvature can partly explain the observed sensitivity of MEG for interictal spikes.
Department of Neurology and Clinical Neurophysiology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, F02.230 Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. ghuiskam@umcutrecht.nl
Geertjan
G
Huiskamp
Zaloa
Z
Agirre-Arrizubieta
Frans
F
Leijten
D001921:Brain / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D001931:Brain Mapping / Q000379:methods; D016000:Cluster Analysis; D003198:Computer Simulation; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008959:Models, Neurological; D012815:Signal Processing, Computer-Assisted