Early epileptic encephalopathy with suppression burst electroencephalographic pattern--an analysis of eight Taiwanese...

Early epileptic encephalopathy with suppression burst (SB) comprises two distinct epileptic syndromes, early infantile epileptic encephalopathy (EIEE) and early myoclonic encephalopathy (EME). We reviewed etiologies, neurological outcome and clinico-electroencephalographic features of EIEE and EME. Chart records of early epileptic encephalopathy with SB from January 1997 to December 2000 were reviewed. These cases fulfilled the diagnostic criteria of EIEE and EME. Totally eight patients (four females, four males) were enrolled. They consisted of three cases of EIEE and five cases of EME. The follow-up periods ranged from 6 to 30 months. For EIEE, two cases had migrational disorders, and one was cryptogenic; for EME, three cases had non-ketotic hyperglycinemia (NKH), one was pyridoxine dependency and one was cryptogenic. The main initial seizure patterns were tonic spasms in EIEE, and were erratic myoclonus in EME. The age of seizure onset ranged from 26 h to 5 days after birth for EIEE, and 2 h to 7 days of life for EME. The SB pattern in the electroencephalography (EEG) was noted mainly during sleep state in EME, but in both awake and sleep states in EIEE. Asymmetric SB pattern and background activities in EEG were found in migrational disorders. The EEG in all cases of EIEE changed to hypsarrhythmia at 4-6 months of age. In EME, only the EEG in cases of NKH evolved to hypsarrhythmia. Response to anti-convulsants was generally poor. All had severe psychomotor retardation. Although EIEE and EME share several common features, differences in terms of seizure seminology and evolution, EEG patterns and etiologies still exist.