Progressive myoclonus epilepsy

Progressive myoclonus epilepsy, also called progressive myoclonic epilepsy or PME, is a rare group of inherited neurodegenerative diseases whose defining features are myoclonus, resistance to treatment and steady neurological deterioration. Most forms are caused by autosomal dominant, autosomal recessive or mitochondrial mutations, and the location of the mutation also shapes how the condition is inherited and treated. Diagnosis is difficult because the group is genetically heterogeneous and some patients have no mutation identified. Age at onset depends on the specific type, from about 6 to 15 years in Unverricht-Lundborg disease to as late as 30 in adult neuronal ceroid lipofuscinoses. Symptoms often include action or stimulus induced myoclonus, seizures, neuropathy and cognitive decline. There is no cure; care aims to control myoclonus and seizures with antiepileptic medication, and the outlook is poor, with many people becoming reliant on a wheelchair and having a shortened life expectancy.