Progressive myoclonus epilepsy

Progressive Myoclonic Epilepsies (PME) are a rare group of inherited neurodegenerative diseases characterized by myoclonus, resistance to treatment, and neurological deterioration. The cause of PME depends largely on the type of PME. Most PMEs are caused by autosomal dominant or recessive and mitochondrial mutations. The location of the mutation also affects the inheritance and treatment of PME. Diagnosing PME is difficult due to their genetic heterogeneity and the lack of a genetic mutation identified in some patients. The prognosis depends largely on the worsening symptoms and failure to respond to treatment. There is no current cure for PME and treatment focuses on managing myoclonus and seizures through antiepileptic medication (AED). The age of onset depends on the specific PME but PME can affect people of all ages. In Unverricht-Lundborg disease (ULD) the age of onset is between 6–15 years, while in Adult Neuronal ceroid lipofuscinoses (Adult NCL) the age of onset can be as late as 30. Symptoms often include action or stimuli induced myoclonus, seizures, neuropathy, cognitive decline, and spike and wave or no cerebral discharges. The prognosis of those diagnosed with PME is poor. The person often becomes reliant on a wheelchair, enters a vegetative state due to myoclonus, and has a shortened life expectancy. The most common symptom of PME is myoclonus. The myoclonus can be fragmented or multifocal and can be triggered by posture, actions, and external stimuli such as light, sound, and touch. The type of myoclonus differs between the types of PME. Other symptoms of PME include generalized, tonic clonic, tonic, and atypical absence seizures. In Lafora's disease the seizures are occipital and the person experiences transient blindness as well as visual hallucinations. The person may also have atypical absences and atonic and complex partial seizures. In Myoclonus epilepsy with ragged-red fibers (MERRF) the person experiences generalized epilepsy along with myoclonus, weakness, and dementia.