Impairment of consciousness during epileptic seizures with special reference to neuronal mechanisms.

Two neuronal structures, i.e., the cerebral cortex and the subcortical structures, were shown by clinical observations to be involved in maintaining consciousness. The alteration of consciousness during epileptic seizures is discussed with respect to these findings: Alterations of consciousness during epileptic seizures may be produced by subcortical, i.e., reticular formation, and/or cortical dysfunction followed by excessive, hypersynchronous neuronal discharges. An impairment of consciousness during absence seizures may be due mainly to cortical dysfunction; during complex partial seizures (CPS), it may be due to dysfunctional subcortical neuronal structures. The mechanisms underlying an alteration of consciousness are defined as causing "irritative" functional disturbances and/or as having "inhibitory" effects on consciousness-related structures.