Pediatric Epilepsy - Myoclonic Status in Nonprogressive Encephalopathies

The possible occurrence of myoclonic epilepsy in children with nonprogressive encephalopathy has been reported in the literature for many years by various authors ( 1–5 ). However, in the majority of these cases, the authors did not fully describe the electroclinical features of the myoclonic epilepsy or the type of encephalopathy. Moreover, they included in their series some cases in which myoclonus was not correlated with overt EEG paroxysmal activity. Additionally, there is proof in the literature, in different forms of epilepsy, of absence status with myoclonias of variable duration defi ned as “minor epileptic status,” “minor motor status” ( 1 ), “obtundation with myoclonia,” and “nonconvulsive status with ataxia” ( 5,6 ). Nevertheless, the deription of an epileptic syndrome characterized by the recurrence of long-lasting myoclonic status (MSNPE) in children with a nonprogressive encephalopathy is relatively scarce ( 7–19 ), probably because polygraphic EEG recordings are usually not routinely performed in clinical practice. A similar electroclinical picture has been described by many authors in children with nonprogressive encephalopathy, Angelman syndrome, and other genetic entities such as 4p- syndrome and Rett syndrome ( 20–26 ). However, only a few authors have stressed how, in some of these cases, the electroclinical features were typically those of an MSNPE ( 27–32 ). Recently, the MSNPE was fi rst proposed in the scheme of the ILAE Task Force on Classifi cation and Terminology ( 33 ) as a “syndrome in development” and later recognized as a well-defi ned epileptic syndrome in the group of epileptic encephalopathies ( 34,35 ). GENERAL