Seizure generation mechanisms in reflex epilepsy.

To know the seizure generation mechanisms in reflex epilepsy, we performed red flicker and flickering geometric pattern stimulations for photosensitive epilepsy, and neuropsychological EEG activation for graphogenic epilepsy. These activations were effective to provoke seizure discharges. The EEG discharges of absence seizure in photosensitive epilepsy started mainly from the posterior regions, which became evident by the reduction of stimulus intensity. Mental activity performed with the hands provoked the central-dominant discharges with unilateral myoclonic seizure as well as generalized discharges with bilateral myoclonic seizure in graphogenic epilepsy. These findings suggest that the initiation of these seizures may relate to the hyperexcitability of the focal cortical areas, which correspond to those activated by the special EEG activation.