Neonatal Developmental and Epileptic Encephalopathies.

The new concept of developmental and epileptic encephalopathy is based on the understanding that many genetic epilepsies are associated with developmental impairment as a direct consequence of the genetic mutation, in addition to the effect of the frequent epileptic activity on brain development. As an example, in infants with KCNQ2 or STXBP1 encephalopathy, seizures may be controlled early after onset or cease spontaneously after a few years, but the developmental consequences tend to remain profound. The term "developmental and epileptic encephalopathy" expresses the concept that the genetic defect may be responsible for both the epilepsy and adverse development which is crucial to understanding the disease process for both families and clinicians. The increased use of EEG monitoring, neuroimaging, and metabolic and genetic testing in the Neonatal Intensive Care Unit has greatly improved our understanding of neonatal-onset epilepsies as seen with the syndromes Ohtahara and Early Myoclonic Encephalopathy outlined in the 1970s into distinct etiology-specific electroclinical phenotypes.