ABSTRACT
Since the early description of myoclonic absences,1-3
it has been generally believed that an epileptic syndrome characterized by the presence of myoclonic absences (MAs) as the only or predominant seizure type could be differentiated from other forms of generalized epilepsy, such as childhood absence epilepsy. This view was accepted by the Commission on Classification and Terminology of the International League Against Epilepsy (ILAE), and epilepsy with myoclonic absences was recognized as a distinct syndrome.4 In the 1989 classification, epilepsy with myoclonic absences was included in the group of cryptogenic or symptomatic generalized epilepsies, based largely on the very variable and sometimes quite poor prognosis. However, in the recent ‘Proposed diagnostic scheme for people with epileptic seizures and with epilepsy’ produced by the ILAE Task Force on Classification and Terminology, it has been tentatively placed among the idiopathic generalized epilepsies.5 Indeed, in their recent review on this epileptic condition, Bureau and Tassinari6
described the existence of at least two forms of epilepsy with myoclonic absences. One form is characterized by a more benign course, eventual disappearance of seizures, and the occurrence of myoclonic absences as the sole, or
predominant, seizure type. In the second form, myoclonic absences are associated with other seizure types, particularly generalized tonic-clonic seizures, and this has a much poorer prognosis than the other idiopathic generalized epilepsies. Furthermore, there have been reports of ‘atypical’ cases characterized by the association of MAs with some degree of mental retardation, neurological abnormalities (e.g. congenital hemiparesis), and chromosomal disorders.7,8
Epilepsy with myoclonic absences is a rare condition, accounting for 0.5-1 per cent of the epilepsies observed in a selected population with epilepsy who attend the Centre Saint-Paul in Marseilles (France). There is a male preponderance (69 per cent), in contrast to the female preponderance in childhood absence epilepsy. Etiologic factors have been reported in about 35 per cent of cases and include prematurity, perinatal brain injury, consanguinity, congenital hemiparesis, and chromosomal disorders.6
