Late-onset, "Gastaut type", childhood occipital epilepsy: an unusual evolution

We report on two girls and one boy with clinical and electroencephalographic features of late-onset childhood epilepsy with occipital paroxysms of the "Gastaut type", showing an unusual evolution. Neurological examination and brain imaging were normal in all three. At the age of 7.5 years, eight years and ten years respectively, the three children presented with episodes of visual symptoms when awake, and in one of them, the seizures were occasionally followed by oculocephalic deviation. The interictal EEG showed bilateral occipital spike-wave activated by eye closing. In two patients, the occipital seizures had been immediately followed by typical absences, since onset; in the other patient, five months after onset. The ictal EEG showed irregular bilateral occipital spike-wave discharges during the visual symptoms, followed by generalized spike-wave activity during the typical absences. The typical absences were activated by hyperventilation; the EEG did not show continuous spikes and waves during slow sleep. These three patients, with typical electroclinical features of "Gastaut type", childhood occipital epilepsy, demonstrated an evolution which, to our knowledge, has not been previously described. We investigated whether this unusual, age-dependent evolution was due to secondary bilateral synchrony or if these electroclinical features represent two types of idiopathic epileptic syndromes in the same patients.