**Abstract**

Epileptic encephalopathies represent a group of devastating epileptic disorders that appear early in life. They are characterized by pharmacoresistant generalized or focal seizures, persistent severe EEG abnormalities, and cognitive dysfunction or decline. The ictal and interictal epileptic discharges are age-specific and either are the main cause or contribute to cognitive deterioration in the idiopathic or symptomatic group, respectively. Despite choosing the most appropriate antiepileptic drugs for the seizure type and syndrome, the results are often disappointing, and polytherapy and/ or alternative therapy becomes unavoidable; in those cases, consideration should be given to the quality of life of the child and carers. In this chapter, we will discuss the clinical and electroencephalographic characteristics and evolution and management of age-related epileptic encephalopathies, recognized by the International League Against Epilepsy, as follows: early infantile epileptic encephalopathy (Ohtahara syndrome), early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, infantile spasms (West syndrome), severe myoclonic epilepsy in infancy (Dravet syndrome), myoclonic-atonic epilepsy (Doose syndrome), Lennox-Gastaut syndrome, epileptic encephalopathy with continuous spike-and-wave during sleep, and Landau-Kleffner syndrome. Their clinical features, prognosis, etiologies, and treatment are presented and updated.

**Keywords:** electroclinical seizures, epileptic encephalopathy, pharmacoresistant epilepsy, epilepsy, electroencephalography
