Progressive myoclonus epilepsy

Myoclonic epilepsy presenting in a cognitively normal adolescent is often related to juvenile myoclonic epilepsy. However, there are similar clinical features that suggest progressive myoclonus epilepsy. These include cognitive or motor regression, progressively worsening seizures, persistent slowing of the background on EEG, as well as family history of epilepsy. Due to variable phenotypes, any family history of epilepsy can be significant. There are multiple causes of progressive myoclonus epilepsy. If there is a possibility of a progressive myoclonus epilepsy, it is essential to exclude mitochondrial disorders as an etiology because valproic acid, often used to treat myoclonic seizures, will worsen underlying mitochondrial disease and precipitate or worsen hepatic failure. There are no specific treatments for progressive myoclonus epilepsy, and management is symptomatic. However, it is important to make the diagnosis in order to allow the family to understand the inheritance pattern, progressive nature, and variable phenotypes of the disease.