Epileptic encephalopathies (including severe epilepsy syndromes).

Epileptic encephalopathies represent a group of devastating epileptic disorders that appear early in life and are characterized by pharmacoresistant generalized or focal seizures, persistent severe electroencephalography (EEG) abnormalities, and cognitive dysfunction or decline. The ictal and interictal epileptic discharges are age-specific and are the main etiologic factors causing cognitive deterioration. This is most obvious in the idiopathic group. In the symptomatic group, the most common causes are structural, congenital, or acquired and rarely some metabolic disorders. In certain cases, clinical and EEG abnormalities persist and may evolve from one type to another as the child grows older. Various factors trigger and sustain the underlying pathophysiologic process and the ongoing epileptic and epileptiform activity during the most critical periods of brain maturation, perpetuating their deleterious effect on the brain. Immune-mediated mechanisms may have a role, suggested by certain encephalopathies responding to immune-modulating treatments and by the finding of various autoimmune antibodies. The chance of a better cognitive outcome improves with early diagnosis and treatment that is appropriate and effective. Current antiepileptic drugs are, in general, not effective: we urgently need new trials in this very special epileptic category. This article briefly reviews the most common epileptic encephalopathies and analyzes the most important clinical issues. Wiley Periodicals, Inc.