Electroclinical overlap of two types of epileptic encephalopathy occurring in the same children in a certain age period?

In this study, we describe three patients who each had an electroclinical overlap of two different epileptic encephalopathies (EE), with onset in a certain age period. Patient 1 had electroclinical features compatible with continuous spikes and waves during slow sleep (CSWSS) syndrome that changed into Lennox-Gastaut syndrome (LGS) (symptomatic, cause porencephalic cyst) at the age of 8.5 years. Patient 2 had LGS which evolved into CSWSS at the age of 6 years (symptomatic, cause polymicrogyria). The third patient had cryptogenic CSWSS syndrome at age the age of 7 years which evolved into LGS at the age of 7.5 years. All three patients could be considered to have two EE: CSWSS syndrome and LGS or to have had overlapping features of these epileptic syndromes.