The clinical and electroencephalographic characteristics of early myoclonic encephalopathy

Abstract

To investigate the clinical and electroencephalographic (EEG) characteristics, therapeutic response and long-term prognosis of early myoclonic encephalopathy. The clinical and EEG data of three patients with early myoclonic encephalopathy were analyzed. These patients were admitted to our hospital between September 2008 and January 2012. The patients were followed up for therapeutic response and long-term prognosis. The age of onset was from 2 to 23 days after birth. All patients had the onset of erratic or fragmentary myoclonus. Two patients had frequent simple focal seizures. One patient had tonic spasms when he was 3 months old. The EEG characteristic of all patients was repetitive suppression-burst pattern. The suppression-burst pattern was characterized by paroxysmal short bursts and long periods of suppression. The EEG paroxysms of one patient was asynchronous over both hemispheres. There is no effective therapy for early myoclonic encephalopathy. A patient died before two years of age. Two patients had severe partial epilepsy and showed very severe retardation. Early myoclonic encephalopathy usually starts in the first month of life. Erratic myoclonus appears first. Myoclonus is the principal features of early myoclonic encephalopathy. Frequent focal seizures occur shortly after erratic myoclonus. Tonic epileptic spasms may develop within 3 - 5 months. The suppression-burst pattern is EEG characteristic. There is no effective therapy for early myoclonic encephalopathy and the prognosis is poor.