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Progressive myoclonic epilepsy type 1 (EPM1) - action myoclonus

(A) On execution of a requested movement (“raise you right hand toward the head”) intense repeated myoclonias maximal in the agonist arm muscles are followed by atonias of long (more than 500 ms) duration, with or without multiple spikes and slow waves on the EEG. (B) Erratic-fragmentary myoclonus at rest: asynchronous in agonist and antagonist muscles, with or without overt EEG correlates. (Back-average analysis, not performed here, may be useful to unveil eventual EEG potentials.) (Courtesy of Cr. C A Tassinari. From: Tassinari AC, Cantalupo G, Rubboli G. Polygraphic recording of epileptic seizures. In: Panayiotopoulos CP, editor. Atlas of epilepsies. London: Springer, 2010:723-40.)