[An electron microscopic observation on spike foci of human epileptic brains]

Twenty cases of ECOG spike foci in epilepsy originally recorded by flaky silver electrodes on the surface of cortices and then to be removed surgically were studied under transmission electron microscope. The ultrastructural changes of the spike foci seemed to be identical in all cases although there were differences in etiologies, locations and seizure types. The presynaptic terminals of axospinal asymmetric synapses were obviously swollen anyhow, the postsynaptic spines were relatively unaffected. The synaptic vesicles were decreasing in number and to be accumulated predominantly at the presynaptic membrane which indicated that these excitatory changes of synapses may play an important role in the mechanism of epileptic abnormal electric activity and the development of epilepsy. Additionally, the ultrastructural changes and the cytopathologic significance of neurons, astrocytes and capillaries are also discussed.