Chapter 44 Myoclonic epilepsies: syndromes and their treatment

Abstract

Publisher Summary This chapter discusses some of the better known myoclonic epilepsies and their treatment. Early myoclonic epilepsies referred to as early infantile epileptic encephalopathy with suppression-burst or Ohtahara syndrome is characterized by a triad of myoclonic, focal, and later tonic seizures. Their clinical manifestations include onset in early infancy, usually within the first three months, with 60% before ten days of age. Erratic and fragmentory myoclonus of the face or limbs, usually asynchronous and asymmetric, are noted early with massive myoclonic jerks appearing later. The main seizures are tonic spasms (similar to West syndrome) with other ictal events being partial and myoclonic. The electroencephalography (EEG) is characterized by suppression-burst pattern with complex bursts of high amplitude spikes and sharp and slow waves both during waking and sleeping states. Multiple etiologies are responsible for the syndrome but the majority of cases are associated with structural brain damage or severe bilateral injury. Early myoclonic encephalopathy is differentiated from Ohtahara syndrome by the main seizure type being erratic myoclonias, focal seizures and clusters of spasms, rather than tonic spasms primarily. Children with severe myoclonic epilepsy in infancy (SMEI), also known as “Dravet syndrome,” have the onset of seizures in the first year of life with development being normal prior to their onset.