Epileptic encephalopathies in early infancy with suppression-burst

Early infantile epileptic encephalopathy with suppression-burst, or Ohtahara syndrome (OS), and early myoclonic encephalopathy (EME) are epileptic encephalopathies with onset of frequent seizures in the neonatal and early infancy period and with a characteristic EEG pattern, namely, suppression-burst, in which higher-voltage bursts of slow waves mixed with multifocal spikes alternate with isoelectric suppression phase. Their nosologic independence is now widely accepted, although some controversy initially occurred because of their common characteristics such as age of onset, EEG features, seizure intractability, and poor prognosis. Major differences between the two syndromes include (1) tonic spasms in OS versus partial seizures and erratic myoclonias in EME, (2) continuous suppression-burst pattern in both waking and sleeping states in OS versus this EEG pattern almost limited to sleep in EME, and (3) static structural brain damage in OS versus genetic or metabolic disorders in EME. The most important differentiating point is their evolutional pattern with age, which may reflect their pathophysiologic difference. Ohtahara syndrome evolves to West syndrome and further to Lennox-Gastaut syndrome with age, but EME demonstrates no unique evolution; namely, it continues as such for a long time or changes into partial epilepsy or severe epilepsy with multiple independent spike foci.