Ictal Source Locations and Cortico–Thalamic Connectivity in Childhood Absence Epilepsy: Associations with Treatment Response

Childhood absence epilepsy (CAE), the most common pediatric epilepsy syndrome, is usually treated with valproic acid (VPA) and lamotrigine (LTG) in China. This study aimed to investigate the ictal source locations and functional connectivity (FC) networks between the cortices and thalamus that are related to treatment response. Magnetoencephalography (MEG) data from 25 patients with CAE were recorded at 300 Hz and analyzed in 1–30 Hz frequency bands. Neuromagnetic sources were volumetrically scanned with accumulated source imaging. The FC networks between the cortices and thalamus were evaluated at the source level through a connectivity analysis. Treatment outcome was assessed after 36–66 months following MEG recording. The children with CAE were divided into LTG responder, LTG non-responder, VPA responder and VPA non-responder groups. The ictal source locations and cortico–thalamic FC networks were compared to the treatment response. The ictal source locations in the post-dorsal medial frontal cortex (post-DMFC, including the medial primary motor cortex and the supplementary sensorimotor area) were observed in all LTG non-responders but in all LTG responders. At 1–7 Hz, patients with fronto–thalamo–parietal/occipital (F–T–P/O) networks were older than those with fronto–thalamic (F–T) networks or other cortico–thalamic networks (p = 0.000). The duration of seizures in patients with F–T–P/O networks at 1–7 Hz was longer than that in patients with F–T networks or other cortico–thalamic networks (p = 0.001). The ictal post-DMFC source localizations suggest that children with CAE might experience initial LTG monotherapy failure. Moreover, the cortico–thalamo–cortical network is associated with age. Finally, the cortico–thalamo–cortical network consists of anterior and posterior cortices and might contribute to the maintenance of discharges.