Encephalopathy with status epilepticus during slow sleep (ESES)

Encephalopathy related to Status Epilepticus during slow Sleep (ESES)(otherwise labelled as Continuous Spikes and Waves during Sleep-CSWS) is an age-related epileptic syndrome characterized by deterioration of cognitive functions and behavior,epilepsy with various seizure types and a peculiar EEG pattern characterized by extreme activation of epileptic discharges during slow sleep, i.e. status epilepticus during sleep (SES). Despite the long-term favourable outcome of epilepsy and SES, the prognosis of this condition is guarded because of the possible persistence of severe neuropsychological and behavioral disturbances into adulthood. Etiology of ESES can be either idiopathic, symptomatic or unknown. In recent years, mutations in GRIN2A and CNKSR2 have been found to associated with the epilepsia-aphasia spectrum, including ESES. The link between the extreme amount of epileptic discharges during sleep and the deterioration of cognitive functions and behavior is poorly understood. Recently, it has been hypothesized that the negative effects of ESES may depend on the impairment of the synaptic homeostasis processes occurring during normal sleep and that are particularly important in the developmental age. Sleep ensures synaptic homeostasis by promoting synaptic weakening/elimination after the increase of synaptic strength that occur during wakefulness. Changes in synaptic strength are reflected in the EEG by changes of sleep slow wave activity (SWA). Recent studies in ESES have failed to show changes of sleep SWA, particularly at the site of the epileptic focus, suggesting a spike-related impairment of the homeostatic recovery of sleep. This impaired synaptic homeostasis in the critical period of development may alter cortical wiring and thereby disrupt, often irreversibly,cognitive functions and behavior, leading to the neuropsychological compromise typical of ESES.