RESUMO
The study aimed to differentiate, according to clinical and electroencephalographical criteria, between the most frequent types of myoclonus epilepsy--Unverricht-Lundborg disease (ULD) and Lafora disease (LD). Two patients with ULD and two with LD, aged 13-16 years, have been examined. In all cases, the diagnosis of myoclonus epilepsy has been verified by using molecular genetic analysis. The differential diagnostic criteria have been ascertained for ULD and LD: the earlier age-of-onset in ULD comparing to LD (8.8 and 12.5 years, respectively); tonic clonic paroxysms in ULD and partial ones with visual aura in LD; a presence of nonepileptical subcortical myoclonus, according to EEG data (visual monitoring); negative myoclonus emerging in manifested stage of LD; appearing of regional epileptiform activity for posterior regions on EEG in LD; more rapid progressiveness of extra pyramidal disturbances with organic dementia outcome in myoclonus LD.