[Polymorphic epilepsy in children. Study of 12 patients]

The purpose of this report is to describe our series of patients with polymorphic epilepsy, an infrequent diagnosis which was previously called severe myoclonic epilepsy.

A retrospective descriptive study of 12 patients diagnosed with polymorphic epilepsy according to the criteria proposed by the International League Against Epilepsy (1989) was carried out. All patients were recruited from the Neuropediatric Unit at our hospital. Minimum follow-up was 18 months, with a maximum of 20 years.

In our opinion, the syndrome's evolution has three clinical EEG phases. The febrile phase, the catastrophic phase and the residual phase. The main interest from a pediatric point of view is the absence of EEG anomalies during the febrile phase, in spite of the severity of the condition. This may lead to confusion of the actual syndrome with complicated febrile seizures, which usually have a better prognosis. Another misleading diagnosis could be post-immunization disorders. To our best knowledge, evolution towards the catastrophic phase cannot be deterred. Antiepileptic drugs, in mono- or poly-therapy, at least until the present, have not proven to be useful in this disorder.