Centre Saint-Paul, Marseille, France
The progressive myoclonus epilepsies (PME) are rare diseases and many clinicians, who have only few opportunities to encounter such patients, may think of them as mythical. However, the category of PME has been retained by the latest classification scheme proposal of the International League Against Epilepsy. PMEs are defined by: 1) generalized epileptic seizures (focal seizures may also occur in certain etiologies), 2) a sometimes invalidating myoclonus, and 3) other neurological symptoms (ataxia, dementia, sensory deficits) that vary according to etiology. Indeed, PMEs are a heterogenous group of conditions, with diverse etiologies. Their prevalence varies according to the ethnic context, and PMEs may appear as fairly frequent in some settings, because of genetic factors (isolate and/or inbreeding, for instance, in PMEs with recessive inheritance). The genetic and biochemical mechanisms underlying PMEs are increasingly recognized. We must nowadays follow a logical diagnostic scheme that will take into account the ethnic and genetic context, the age at onset of symptoms and the respective weight of symptoms. New therapeutic approaches are under development, and the available purely symptomatic treatments can be used to best possible effect. It is thus possible to recognize PMEs as a group of conditions appearing either as epilepsy, or as a movement disorder, or still under the mask of various neurological or cognitive symptoms. It is also possible to organize a logical, comprehensive care for patients with PME.