Myoclonic status in non-progressive encephalopaties (MSNPE)

The Authors review the electroclinical pictures of a large population of 37 females and 21 males outlining the existance of an epileptic syndrome characterized by the recurrence of long-lasting myoclonic status in children with a non progressive encephalopathy. The Authors discuss the etiology in 50% of the cases is genetic and in 25% the diagnosis was of Angelmn Syndrome. Only an early recognition allows an adequate treatment avoiding or limiting the worsening of the neuropsychological impairment. Furthermore a correct electroclinical analysis allows to distinguish three peculiar subsets having an important diagnostic and prognostic significance. The first characterized by the association of absences, subcontinuous jerks at times rhythmic or arrhythmic mainly positive, brief myoclonic absences and hypnagogic startles allowing an early diagnosis of Angelman syndrome. The second characterized by the association of absence status and continuous rhythmic myoclonus, mainly negative, mixed with sudden uncontrolled continuous dyskinetic movements leading to a clinical picture of hyperkinetic aposturality. This condition affecting only females probably with cortical malformations, remains invariably refractory to all treatment. The third characterized by a continuous spike activity on rolandic regions persisting throughout life accompanied by bilateral rhythmic myoclonias followed by an inhibitory phenomenon, leading to a progressive neuromotor deterioration corresponding to a form of myoclonic progressive epilepsy in absence of a progressive disease. Also, in these cases, the aetiological factor is frequently constituted by a cortical dysplasia involving the motor area.