Pathological changes in the epileptogenic foci of children with intractable epilepsy

Objective To investigate pathological changes in the epileptogenic foci of children with intractable epilepsy and their clinical significance.Methods Thirty children with intractable epilepsy were included in the study.The epileptogenic foci were surgically resected and pathological changes in the obtained specimens were observed under a light microscope(LM) and a transmission electron microscope(TEM).Results Under the LM,cortical dysplasia was found in 14 cases(47%),hippocampal sclerosis in 11 cases(37%),dysembryoplastic neuroepithelial tumor in 1 case(3%),ganglioglioma in 1 case(3%),and encephalomalacia in 3 cases(10%).The TEM observation revealed pathological changes in the ultrastructure of the hippocampus and extra-hippocampal cortex,such as changes in the number of synapses and synaptic structure,decrease in neurons and karyopyknosis,swelling and degeneration of astrocytes,and changes in mitochondrial structures.Conclusions Pathological changes in the hippocampus and extra-hippocampal cortex,especially synaptic remodeling,may be the morphological basis for spontaneous recurrent seizures in children with intractable epilepsy.The pathological changes and epileptiform activity are related to an imbalance between excitatory and inhibitory neurotransmission.