Abstract
Surgery is increasingly proposed as a treatment for children with medically refractory
partial epilepsy. The outcome after surgery depends on complete resection of the epileptogenic
zone correlates. Despite multimodal preoperative assessment, 40–60% of children require
intracranial electroencephalography (EEG) recording. Standard EEG can be easily performed
with 20 to 30 electrodes in children of all ages. Increasing the number of electrodes
(high-density [HD] EEG) significantly improves the spatial resolution of EEG and allows
source localization of the epileptogenic focus. In adults, this technique has been
validated for source localization of the epileptic focus and contributes to a better
understanding of the neural networks involved in epilepsy. In this review, we discuss
the pediatric specificities of HD EEG and source localization in order to define the
value of this technique in the preoperative assessment of children with refractory
partial epilepsy. Source localization using HD EEG requires several steps. The first
step, elaboration of the head model, must take into account the heterogeneity of skull
bone thickness, persistence of the fontanelles in younger infants, and the unknown
conductivities of anatomical structures in children. The second step consists of defining
the number of electrodes, which depends on the age and cortical gyration of the brain.
Finally, after extraction of meaningful information (interictal or ictal features),
the third step consists of defining the specific modalities required in pediatric
subjects to resolve the inverse problem to determine source localization.
Keywords
High-density EEG - children - epilepsy - source localization - ictal - inter-ictal
spikes - seizures
