Correlation of invasive EEG and scalp EEG.
Ever since the implementation of invasive EEG recordings in the clinical setting, it has been perceived that a considerable proportion of epileptic discharges present at a cortical level are missed by routine scalp EEG recordings. Several in vitro, in vivo, and simulation studies have been performed in the past decades aiming to clarify the interrelations of cortical sources with their scalp and invasive EEG correlates. The amplitude ratio of cortical potentials to their scalp EEG correlates, the extent of the cortical area involved in the discharge, as well as the localization of the cortical source and its geometry have been each independently linked to the recording of the cortical discharge with scalp electrodes. The need to elucidate these interrelations has been particularly imperative in the field of epilepsy surgery with its rapidly growing EEG-based localization technologies. Simultaneous multiscale EEG recordings with scalp, subdural and/or depth electrodes, applied in presurgical epilepsy workup, offer an excellent opportunity to shed some light to this fundamental issue. Whereas past studies have considered predominantly neocortical sources in the context of temporal lobe epilepsy, current investigations have included deep sources, as in mesial temporal epilepsy, as well as extratemporal sources. Novel computational tools may serve to provide surrogates for the shortcomings of EEG recording methodology and facilitate further developments in modern electrophysiology.
Division of Child Neurology, University Children's Hospital, Steinwiesstrasse 75, 8032 Zürich, Switzerland; Swiss Epilepsy Center, Bleulerstrasse 60, 8008 Zürich, Switzerland; Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France. Electronic address: georgia.ramantani@kispi.uzh.ch.
Georgia
G
Ramantani
Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France; Department of Neurology, Central University Hospital, CHU de Nancy, Nancy, France; Medical Faculty, University of Lorraine, Nancy, France.
Louis
L
Maillard
Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France; Department of Neurology, Central University Hospital, CHU de Nancy, Nancy, France.
Laurent
L
Koessler
D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D004567:Electrodes, Implanted; D004569:Electroencephalography; D006801:Humans; D012535:Scalp
Electroencephalography; Epilepsy surgery; Interictal spikes; Intracranial recordings; Refractory epilepsy; Source localization